WO2020202474A1 - Steel sheet, tailored blank, hot-pressed molded product, steel pipe, and hollow quenched molded product - Google Patents

Steel sheet, tailored blank, hot-pressed molded product, steel pipe, and hollow quenched molded product Download PDF

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Publication number
WO2020202474A1
WO2020202474A1 PCT/JP2019/014687 JP2019014687W WO2020202474A1 WO 2020202474 A1 WO2020202474 A1 WO 2020202474A1 JP 2019014687 W JP2019014687 W JP 2019014687W WO 2020202474 A1 WO2020202474 A1 WO 2020202474A1
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WO
WIPO (PCT)
Prior art keywords
thickness
intermetallic compound
aluminum
steel sheet
steel plate
Prior art date
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PCT/JP2019/014687
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French (fr)
Japanese (ja)
Inventor
雄二郎 巽
富士本　博紀
泰山　正則
康信 宮▲崎▼
優貴 鈴木
Original Assignee
日本製鉄株式会社
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Application filed by 日本製鉄株式会社 filed Critical 日本製鉄株式会社
Priority to JP2019530107A priority Critical patent/JP6601598B1/en
Priority to PCT/JP2019/014687 priority patent/WO2020202474A1/en
Publication of WO2020202474A1 publication Critical patent/WO2020202474A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
    • B21D22/20—Deep-drawing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/12—Aluminium or alloys based thereon

Definitions

  • the present disclosure relates to steel sheets, tailored blanks, hot press molded products, steel pipes, and hollow hardened molded products.
  • Hot press molding (hereinafter, may be referred to as "hot stamping") is attracting attention as one of the techniques for molding automobile members.
  • hot stamping a steel sheet for hot pressing is heated to a high temperature and pressed in a temperature range equal to or higher than the Ar 3 transformation temperature. Further, in hot stamping, a press-formed steel sheet is rapidly cooled by heat removal from a die, and a transformation is caused at the same time as molding under a press pressure.
  • hot stamping is a technique capable of producing a press-molded product having high strength and excellent shape freezing property.
  • tailored blanks in which the end faces of at least two butt-welded steel sheets are butted and joined by laser welding, plasma welding, etc. are used for pressing. It is applied as a material. Since the tailored blank joins a plurality of butt-welded steel plates according to the purpose, the plate thickness and strength can be freely changed in one component. As a result, by using the tailored blank, it is possible to improve the functionality of the automobile member and reduce the number of parts of the automobile member. Further, by hot stamping using a tailored blank, it is possible to manufacture a high-strength stamped product in which the plate thickness, strength and the like are freely changed.
  • the tailored blank When a tailored blank is used as a press material and an automobile member is molded by hot stamping, the tailored blank is heated to, for example, a temperature range of 800 ° C to 1000 ° C. For this reason, a steel plate plated with aluminum such as Al—Si, which has a high plating boiling point, is often used for the tailored blank for hot stamping.
  • Patent Documents 1 to 5 disclose that in a steel sheet having an aluminum plating layer, an intermetallic compound layer remains and the aluminum plating layer is removed in a region around the steel sheet.
  • Patent Documents 3 and 4 disclose requirements for a welded portion to maintain a required strength in a tailored blank for hot stamping formed by butt laser welding a steel sheet having an aluminum plating layer.
  • Patent Document 5 discloses that in a steel sheet having a plating layer such as aluminum plating, the edge region of the steel sheet is subjected to laser ablation treatment.
  • a steel sheet plated with a metal mainly containing aluminum has an intermetallic compound layer provided on the base steel sheet and an aluminum-plated layer provided on the intermetallic compound layer (for example, Patent Document 1). See ⁇ 5).
  • a tailored blank provided with a steel plate having a large thickness of an intermetallic compound layer is hot stamped to produce a hot press molded product (hereinafter, may be referred to as a “hot stamp molded product”), the welded portion. Cracks or the like may occur in the hot stamped product in areas other than the above. This phenomenon is considered to be due to the large thickness of the hard and brittle intermetallic compound layer.
  • the hot stamped product is preferably manufactured using a tailored blank having a steel plate having a thin intermetallic compound layer.
  • Patent Document 1 and Patent Document 2 disclose that a steel sheet is obtained by removing the aluminum plating layer of the planned welding portion to leave an intermetallic compound layer, and using this steel sheet as a steel sheet for butt welding. Then, a tailored blank is formed in which the end faces of the region of the steel sheet in which the intermetallic compound layer remains are butt-welded, and by using this tailored blank, breakage of the weld metal in the hot stamped product can be avoided. It is disclosed.
  • Patent Document 1 and Patent Document 2 disclose that the hot stamped molded product has corrosion resistance.
  • the corrosion resistance at the welded portion is not yet sufficient after being coated on the hot stamped molded product, and further improvement of the corrosion resistance after coating has been required.
  • An object of the present disclosure is that in a steel sheet for butt welding using a steel sheet having a thin metal-to-metal compound layer, a decrease in tensile strength of a joint is suppressed, and even after coating on a hot press-formed product. It is an object of the present invention to provide a steel sheet for butt welding, which can obtain a tailored blank having excellent corrosion resistance after painting of a welded portion.
  • the present disclosure includes the following aspects.
  • the thickness of the aluminum plating layer per side of the steel sheet other than the edge is a 0 ⁇ m, and the thickness of the intermetallic compound layer (IMC 0 ) is b 0 ⁇ m.
  • the thickness of the aluminum-plated layer per one side of at least a part of the edge of the steel sheet is a 1 ⁇ m, and the thickness of the intermetallic compound layer (IMC 1 ) is b 1 ⁇ m.
  • Equation (1) b 1 ( ⁇ m)> b 0 ( ⁇ m) Equation (2): 3 ⁇ m ⁇ b 0 ( ⁇ m) ⁇ 10 ⁇ m Equation (3): 0.8% ⁇ ⁇ 2 ⁇ (a 1 ( ⁇ m) + b 1 ( ⁇ m)) / t 0 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5% (However, the thickness a 1 of the aluminum plating layer includes 0) ⁇ 2>
  • the base steel plate is C: 0.02% to 0.58%, Mn: 0.20% to 3.00%, Al: 0.005% to 0.20%, Ti: 0% in terms of mass%.
  • Nb 0% ⁇ 0.20%
  • V 0% ⁇ 1.0%
  • W 0% ⁇ 1.0%
  • Cr 0% ⁇ 1.0%
  • Mo 0% ⁇ 1.0%
  • Cu 0% to 1.0%
  • Ni 0% to 1.0%
  • B 0% to 0.0100%
  • Mg 0% to 0.05%
  • Ca 0% ⁇ 0.05%
  • REM 0% to 0.05%
  • Bi 0% to 0.05%
  • Si 0% to 2.00%
  • P 0% to 0.03%
  • S 0%
  • the steel plate according to ⁇ 1> which has a chemical composition of ⁇ 0.010%, N: 0% to 0.010%, and the balance: Fe and impurities.
  • ⁇ 3> The steel sheet according to ⁇ 1> or ⁇ 2>, wherein the thickness of the aluminum-plated layer at a portion other than the edge portion is 8 ⁇ m to 50 ⁇ m.
  • a tailored blank comprising a weld metal and at least two steel plate portions connected to the weld metal.
  • the at least two steel plate portions have an edge portion connected to the weld metal and a portion other than the edge portion.
  • at least one steel plate portion is an edge portion connected to the weld metal, and intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate.
  • An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in a portion other than the edge portion in this order.
  • the thickness of the aluminum-plated layer per one surface at least a part of the edge connected to the weld metal is a 1 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 1 ) is b 1 ⁇ m.
  • the thickness of the aluminum plating layer per one side in the portion other than the edge portion connected to the weld metal is a 0 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 0 ) is b 0 ⁇ m.
  • Equation (1) b 1 ( ⁇ m)> b 0 ( ⁇ m) Equation (2): 3 ⁇ m ⁇ b 0 ( ⁇ m) ⁇ 10 ⁇ m Equation (3): 0.8% ⁇ ⁇ 2 ⁇ (a 1 ( ⁇ m) + b 1 ( ⁇ m)) / t 0 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5% (However, the thickness a 1 of the aluminum plating layer includes 0) ⁇ 5> A hot press-formed product comprising a weld metal and at least two steel plate portions connected to the weld metal.
  • the at least two steel plate portions have an edge portion connected to the weld metal and a portion other than the edge portion.
  • at least one steel plate portion is an edge portion connected to the weld metal
  • intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate.
  • An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in a portion other than the edge portion in this order.
  • the thickness of the aluminum-plated layer per one side at least a part of the edge connected to the weld metal is a 2 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 2 ) is b 2 ⁇ m.
  • Equation (4) 0.8% ⁇ ⁇ 2 ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) / t 1 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5%
  • Equation (5) 10 ⁇ m ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) (However, the thickness a 2 of the aluminum plating layer includes 0) ⁇ 6>
  • a steel pipe comprising a weld metal and a steel plate portion in which two peripheral edges are formed in an open tubular shape facing each other and the weld metal is connected to the two peripheral edges.
  • the steel plate portion has at least one steel plate portion, and the at least one steel plate portion has an edge portion connected to the weld metal and a portion other than the edge portion.
  • the at least one steel plate portion is an edge portion connected to the weld metal, and intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate, and the portion other than the edge portion is the said.
  • An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order.
  • the thickness of the aluminum-plated layer per one surface at least a part of the edge connected to the weld metal is a 1 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 1 ) is b 1 ⁇ m.
  • the thickness of the aluminum plating layer per one side in the portion other than the edge portion connected to the weld metal is a 0 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 0 ) is b 0 ⁇ m.
  • the steel plate portion has at least one steel plate portion, and the at least one steel plate portion has an edge portion connected to the weld metal and a portion other than the edge portion.
  • the at least one steel plate portion is an edge portion connected to the weld metal, and intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate, and the portion other than the edge portion is the said.
  • An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order.
  • the thickness of the aluminum plating layer per one side at least a part of the edge connected to the weld metal is a 2 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 2 ) is b 2 ⁇ m.
  • Equation (4) 0.8% ⁇ ⁇ 2 ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) / t 1 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5%
  • Equation (5) 10 ⁇ m ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) (However, the thickness a 2 of the aluminum plating layer includes 0)
  • a decrease in tensile strength of the joint is suppressed, and even after coating on a hot press-formed product.
  • a steel sheet for butt welding which can obtain a tailored blank having excellent corrosion resistance after painting of a welded portion.
  • FIG. 1 is an enlarged schematic cross-sectional view showing an example of the periphery of the edge portion of the planned welding portion in the butt welding steel plate of the present disclosure.
  • FIG. 2 is an enlarged schematic cross-sectional view showing another example around the edge portion of the planned welding portion in the butt weld steel sheet of the present disclosure.
  • FIG. 3 is an enlarged schematic perspective view showing another example around the edge portion of the planned welding portion in the butt weld steel sheet of the present disclosure.
  • FIG. 4 is an enlarged cross-sectional photograph showing an example of an untreated edge portion.
  • FIG. 5 is an enlarged cross-sectional photograph showing an example of an edge portion of a planned welding portion in the butt welding steel plate of the present disclosure.
  • FIG. 6 is a schematic view showing an example of a cross section of a welded portion in the tailored blank of the present disclosure.
  • FIG. 7 is an enlarged cross-sectional photograph of the tailored blank formed through the untreated edges of the two butt-welded steel plates in the vicinity of the weld metal.
  • FIG. 8 is an enlarged cross-sectional photograph of the tailored blank formed in the vicinity of the weld metal of the two butt-welded steel sheets of the present disclosure formed through the edge of the planned welding portion.
  • FIG. 9 is a schematic schematic view showing an example of the steel pipe of the present disclosure.
  • FIG. 10 is a schematic schematic view showing another example of the steel pipe of the present disclosure.
  • the steel sheet of the present disclosure indicates a steel sheet that forms a tailored blank by butt welding with another steel sheet, and will be referred to as a butt welding steel sheet below.
  • the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
  • the content of the component (element) may be referred to as "C amount" in the case of the content of C (carbon), for example.
  • the content of other elements may be described in the same manner.
  • the term "process” is included in this term not only as an independent process but also as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. ..
  • the term “base steel sheet” refers to a steel sheet before aluminum plating, and represents a steel sheet in a state before the intermetallic compound layer and the aluminum plating layer are provided.
  • the term “intermetallic compound layer” refers to an intermetallic compound layer formed between the base steel sheet and the aluminum plating when aluminum plating is applied to both surfaces of the base steel sheet.
  • the term “aluminum plating layer” refers to a region of aluminum plating applied on a base steel sheet excluding an intermetallic compound layer.
  • the term “cross section” of a steel sheet for butt welding refers to a cross section cut in the plate thickness direction. Specifically, in FIG.
  • the plate thickness direction of the butt-welding steel plate is Z
  • the direction in which the planned welding portion extends is X.
  • the direction orthogonal to the direction Z and the direction X is defined as Y.
  • the cross section means a cross section cut by the YZ plane.
  • the X, Y, and Z directions shown in FIG. 1 indicate the same directions as the X, Y, and Z directions shown in FIG.
  • the term "edge" of a steel sheet for butt welding is a region located around the steel sheet for butt welding, which is the maximum, and is the edge of the steel sheet as a steel sheet for butt welding. Represents an area within 5 mm from.
  • the "edge" of the butt-welding steel sheet represents a position where the end face is in contact with the surface of the butt-welding steel sheet facing in the plate thickness direction (that is, the surface of the steel sheet).
  • the term "end face” of a steel sheet for butt welding refers to a surface in which the surface in the plate thickness direction is exposed between the surfaces facing each other on the plate thickness direction side.
  • the terms "a portion other than the edge portion” and "a region other than the edge portion” of the butt-welding steel sheet refer to a region excluding the edge portion of the steel sheet as a butt-welding steel sheet.
  • the "part other than the edge portion” and the “region other than the edge portion” represent the central portion of the butt welding steel plate, and in the minimum case, the opposite width of the butt welding steel plate (that is, from the facing end faces). It occupies the area excluding 5 mm ⁇ 2 from the length to the end face).
  • the term "welded portion” refers to a region including a weld metal and a portion around which the increase in thickness of the intermetallic compound layer is saturated.
  • the butt welding steel sheet of the present disclosure an intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order. That is, the butt welding steel sheet of the present disclosure is formed from such an aluminum-plated steel sheet. Further, in the butt welding steel sheet of the present disclosure, the thickness of the aluminum plating layer per one side in the portion other than the edge of the butt welding steel sheet is a 0 ⁇ m, and the thickness of the intermetallic compound layer (IMC 0 ) is b 0.
  • the thickness of the aluminum-plated layer per one side of at least a part of the edge of the butt-welding steel sheet is a 1 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 1 ) is b 1 ⁇ m.
  • Equation (1) b 1 ( ⁇ m)> b 0 ( ⁇ m) Equation (2): 3 ⁇ m ⁇ b 0 ( ⁇ m) ⁇ 10 ⁇ m Equation (3): 0.8% ⁇ ⁇ 2 ⁇ (a 1 ( ⁇ m) + b 1 ( ⁇ m)) / t 0 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5%
  • the aluminum-plated steel sheet applied as the butt-welding steel sheet of the present disclosure has a base steel sheet and aluminum-plated layers provided on both sides of the base steel sheet. Further, an intermetallic compound layer (IMC 0 ) containing iron and aluminum is provided between the base steel plate and the aluminum plating layer. Further, at least a part of the edge portion of the butt welding steel plate has the intermetallic compound layer (IMC 1 ) provided on both surfaces of the base steel plate.
  • the intermetallic compound layer (IMC 1) thickness is greater than the thickness of the intermetallic compound layer in the region other than the edge (IMC 0) (i.e., to satisfy the above equation (1).).
  • the thickness of the intermetallic compound layer (IMC 0 ) in the region other than the edge of the butt welding steel sheet is 3 ⁇ m to 10 ⁇ m (that is, the above formula (2) is satisfied). Then, the relationship of the above formula (3) is satisfied at the edge portion where the intermetallic compound layer (IMC 1 ) is formed.
  • the plate thickness t 0 of the base steel plate is a value converted to ⁇ m. When there is no aluminum plating layer on the intermetallic compound layer (IMC 1 ), a 1 is 0 (zero) ⁇ m.
  • the shape of the steel plate for butt welding is not particularly limited.
  • a hot stamped product obtained by applying a steel plate plated with aluminum as a steel plate for butt welding and hot stamping a tailored blank obtained by butt welding the end faces of the edges of the steel plate for butt welding is known.
  • Patent Documents 1 to 5 For example, when a steel plate with an excessively thick intermetallic compound layer is used as a steel plate for butt welding to obtain a tailored blank and then a hot stamped product is obtained, the aluminum plating layer and the intermetallic compound are formed in areas other than the welded portion. Cracks and chips may occur in the layer.
  • the intermetallic compound layer is hard and brittle.
  • the too thick intermetallic compound layer existing in the base steel sheet cannot withstand the load during hot stamping, and as a result, cracks and chips occur. If the cracks and chips propagate to the base steel sheet, the corrosion resistance of the base steel sheet is lowered. Therefore, it is preferable that the thickness of the intermetallic compound layer is not too thick in the region other than the welded portion.
  • the thickness of the intermetallic compound layer is not too thin.
  • the interfacial roughness between the intermetallic compound layer and the aluminum plating layer tends to decrease.
  • the aluminum component of the aluminum plating layer melted by butt welding and heating by hot stamping becomes easy to move.
  • the aluminum component of the molten aluminum plating layer moves, the aluminum plating layer hangs down in hot stamping, and the uniformity of the thickness decreases.
  • the thickness of the intermetallic compound layer is not too thin.
  • Patent Document 1 and Patent Document 2 in order to avoid breakage of the weld metal, as described above, butt welding in which the aluminum plating layer of the welded portion to be welded is removed and the intermetal compound layer remains.
  • a tailored blank is disclosed in which a steel plate for butt welding is used and a planned welding portion of the steel plate for butt welding is butt welded. Then, in the hot stamp molded product using this tailored blank, the decrease in welding strength can be suppressed.
  • the butt-welding steel sheets disclosed in Patent Documents 1 and 2 have an aluminum plating (Al—Si metal plating) layer provided on the base steel sheet, and a metal is provided between the base steel sheet and the aluminum plating layer. An inter-compound layer is formed. Since the intermetallic compound layer is relatively fragile, an inhibitor is added to the molten metal bath to limit the growth of the intermetallic compound layer.
  • the aluminum plating layer is as thick as 20 ⁇ m, while the intermetallic compound layer is as thin as 5 ⁇ m.
  • the aluminum plating layer is removed from the planned welded portion of the butt-welded steel sheet by a brush or laser ablation before the tailored blank is manufactured.
  • a thin intermetallic compound layer remains.
  • the corrosion resistance of the welded portion after painting becomes inferior due to the thin thickness of the intermetallic compound layer.
  • the thickness of the intermetallic compound layer is thin, the amount of aluminum mixed in the weld metal is small. Therefore, in the butt welding steel sheets disclosed in Patent Document 1 and Patent Document 2, scale (iron compound) is likely to be generated on the surface of the weld metal by being heated to a high temperature at the time of hot stamping. As a result, when the hot stamp molded product is painted, the adhesiveness of the paint is lowered, and the corrosion resistance after painting at the welded portion is inferior.
  • the butt welding steel sheet of the present disclosure at least an intermetallic compound layer (IMC 1 ) is formed on both sides of the base steel sheet at least a part of the edge portion of the butt welding steel sheet. Then, the thickness of the intermetallic compound layer (IMC 1) is thicker than the thickness of the intermetallic compound layer formed in a region other than the edge (IMC 0). Therefore, due to the thickness of the intermetallic compound layer (IMC 1 ) formed in at least a part of the edge portion, the butt weld steel sheet of the present disclosure is formed even after being coated on a hot stamped product. It is considered that the welded part has excellent corrosion resistance.
  • the steel sheet for butt welding of the present disclosure has a thick intermetallic compound layer (IMC 1 ) formed at least a part of the edge of the steel sheet, aluminum is contained in the weld metal after butt welding. It is mixed moderately. Therefore, the generation of scale is suppressed on the surface of the weld metal, so that the chemical conversion treatment property is improved and the adhesiveness of the paint is improved. As a result, it is considered that the steel sheet for butt welding of the present disclosure is excellent in corrosion resistance after coating of the welded portion even after coating on the hot stamped molded product.
  • IMC 1 intermetallic compound layer
  • the butt-welded steel sheet of the present disclosure is made of aluminum having no aluminum plating layer or a reduced thickness on a thick intermetallic compound layer (IMC 1 ) formed at a planned welding portion at the edge of the steel sheet. There is a plating layer. Therefore, in the butt-welding steel sheet of the present disclosure, when the end faces of the edges having the intermetallic compound layer (IMC 1 ) are butt-welded and welded, a large amount of aluminum is mixed in the weld metal due to the aluminum plating layer. Is suppressed.
  • the thickness of the intermetallic compound layer (IMC 1) is larger than the thickness of the intermetallic compound layer (IMC 0), aluminum-plated layer is formed in a region other than the edge, to melt at butt welding Movement is suppressed. Therefore, the amount of aluminum mixed in the weld metal is suppressed. That is, an appropriate amount of aluminum due to the aluminum plating layer is mixed with the weld metal. As a result, the weld metal suppresses the decrease in hardenability, so that the mechanical strength of the joint can be ensured.
  • the thickness of the intermetallic compound layer (IMC 0 ) is thin, cracks and omissions of the aluminum plating layer and the intermetallic compound layer (IMC 0 ) during hot stamping are suppressed. .. As a result, the deterioration of corrosion resistance in the region other than the edge of the hot stamped product is suppressed.
  • the butt welding steel sheet of the present disclosure has a numerical range of 0.8% to 3.5% in the above-mentioned formula (3).
  • the numerical value of the formula (3) is in this range, aluminum is appropriately mixed in the weld metal. Therefore, the decrease in mechanical strength of the hot stamped molded product is suppressed, and the decrease in corrosion resistance after painting is suppressed.
  • the base steel sheet is a steel sheet before aluminum plating.
  • the base steel sheet may be obtained by a usual method and is not particularly limited.
  • the base steel plate may be either a hot-rolled steel plate or a cold-rolled steel plate.
  • the thickness of the base steel sheet may be set according to the purpose, and is not particularly limited.
  • the thickness of the base steel sheet is such that the total thickness of the steel sheet after the aluminum plating layer is provided is 0.8 mm to 4 mm, and further, the thickness is 1 mm to 3 mm. The thickness can be mentioned.
  • the base steel sheet it means various properties related to mechanical deformation and fracture such as high mechanical strength (for example, tensile strength, yield point, elongation, drawing, hardness, impact value, fatigue strength, etc.). It is preferable to use a steel plate formed so as to have.
  • Examples of the preferable chemical composition of the base steel sheet include the following chemical compositions.
  • C 0.02% to 0.58%, Mn: 0.20% to 3.00%, Al: 0.005% to 0.20%, Ti: 0% to 0.20%, Nb: 0% to 0.20%, V: 0% to 1.0%, W: 0% to 1.0%, Cr: 0% to 1.0%, Mo: 0% to 1.0%, Cu: 0% to 1.0%, Ni: 0% to 1.0%, B: 0% to 0.0100%, Mg: 0% to 0.05%, Ca: 0% to 0.05%, REM: 0% to 0.05%, Bi: 0% to 0.05%, Si: 0% to 2.00%, P: 0.03% or less, S: 0.010% or less, N: 0. It has a chemical composition of 010% or less, and the balance: Fe and impurities.
  • % indicating the content of the component (element) means “mass%”.
  • C (C: 0.02% to 0.58%) C is an important element that enhances the hardenability of the base steel sheet and mainly determines the strength after quenching. Further lowering the three points A, it is an element which promotes lowering the quenching temperature. If the amount of C is less than 0.02%, the effect may not be sufficient. Therefore, the amount of C is preferably 0.02% or more. On the other hand, when the amount of C exceeds 0.58%, the toughness of the hardened portion is significantly deteriorated. Therefore, the amount of C is preferably 0.58% or less. It is preferably 0.45% or less.
  • Mn is a very effective element for enhancing the hardenability of the base steel sheet and stably securing the strength after quenching. If the amount of Mn is less than 0.20%, the effect may not be sufficient. Therefore, the amount of Mn is preferably 0.20% or more. It is preferably 0.80% or more. On the other hand, if the amount of Mn exceeds 3.00%, not only the effect is saturated, but also it may be difficult to secure stable strength after quenching. Therefore, the amount of Mn is preferably 3.00% or less. It is preferably 2.40% or less.
  • Al functions as a deoxidizing element.
  • Al has an effect of reducing oxide-based inclusions that adversely affect the mechanical strength of the base steel sheet. If the amount of Al is less than 0.005%, it may be difficult to obtain the effect of the above action. Therefore, the amount of Al is preferably 0.005% or more. On the other hand, if the amount of Al exceeds 0.20%, the effect of the above action is saturated, which is disadvantageous in terms of cost. Therefore, the amount of Al is preferably 0.20% or less.
  • Ti, Nb, V, and W are elements that promote mutual diffusion of Fe and Al in the aluminum-plated layer and the base steel sheet. Therefore, at least one of Ti, Nb, V, and W may be contained in the base steel sheet. However, if 1) the amount of Ti and Nb exceeds 0.20%, or 2) the amount of V and W exceeds 1.0%, the effect of the above action is saturated, which is disadvantageous in terms of cost. Therefore, the Ti amount and the Nb amount are often 0.20% or less, and the V amount and the W amount are preferably 1.0% or less.
  • the Ti amount and Nb amount are preferably 0.15% or less, and the V amount and W amount are preferably 0.5% or less.
  • the lower limit of the Ti amount and the Nb amount is 0.01% or more, and the lower limit values of the V amount and the W amount are 0.1% or more.
  • Cr, Mo, Cu, Ni, and B are elements that are effective in enhancing the hardenability of the base steel sheet and stably ensuring the strength after quenching. Therefore, one or more of these elements may be contained. However, even if the contents of Cr, Mo, Cu, and Ni are more than 1.0% and the amount of B is more than 0.0100%, the above effect is saturated and it is disadvantageous in terms of cost. Therefore, the content of Cr, Mo, Cu, and Ni is preferably 1.0% or less.
  • the amount of B is preferably 0.0100% or less, preferably 0.0080% or less. In order to obtain the above effect more reliably, it is preferable that the content of Cr, Mo, Cu, and Ni is 0.1% or more, and the content of B is 0.0010% or more.
  • Ca, Mg, and REM have the effect of refining the morphology of inclusions in steel and preventing the occurrence of cracks during hot press forming due to inclusions. Therefore, one or more of these elements may be contained. However, when added in excess, the effect of miniaturizing the morphology of inclusions in steel is saturated, which only increases the cost. Therefore, the Ca amount is preferably 0.05% or less, the Mg amount is 0.05% or less, and the REM amount is 0.05% or less. In order to obtain the effect of the above action more reliably, it is preferable to satisfy any one of Ca amount of 0.0005% or more, Mg amount of 0.0005% or more, and REM amount of 0.0005% or more.
  • REM refers to a total of 17 elements of Sc, Y and lanthanoid, and the content of REM refers to the total content of these elements.
  • lanthanoids they are industrially added in the form of misch metal.
  • Bi is an element that becomes a solidified nucleus in the solidification process of molten steel and has an effect of suppressing segregation (for example, Mn) into the dendrite secondary arm spacing by reducing the dendrite secondary arm spacing. Therefore, Bi may be contained.
  • Mn segregation
  • Bi for a steel sheet that often contains a large amount of Mn, such as a steel sheet for hot pressing, Bi has an effect of suppressing deterioration of toughness due to segregation of Mn. Therefore, it is preferable that such a steel grade contains Bi.
  • Bi even if Bi is contained in an amount of more than 0.05%, the effect of the above action is saturated, resulting in an increase in cost.
  • the amount of Bi is set to 0.05% or less. It is preferably 0.02% or less.
  • the Bi amount is preferably 0.0002% or more. More preferably, it is 0.0005% or more.
  • Si 0% to 2.00%
  • Si is a solid solution strengthening element and can be effectively utilized up to 2.00%.
  • the amount of Si is preferably 2.00% or less.
  • the preferred upper limit is 1.40% or less, more preferably 1.00% or less.
  • the lower limit is not particularly limited, and 0.01% or more is preferable in order to obtain the effect of the above action more reliably.
  • P is an element contained as an impurity. If P is contained in excess, the toughness of the base steel sheet tends to decrease. Therefore, the amount of P is preferably 0.03% or less. It is preferably 0.01% or less. The lower limit of the amount of P does not need to be specified.
  • the amount of P may be 0% or more than 0%. From the viewpoint of cost, it is preferably 0.0002% or more.
  • S is an element contained as an impurity and has an action of forming MnS and embrittlement of the base steel sheet. Therefore, the amount of S is preferably 0.010% or less. A more desirable amount of S is 0.004% or less. The lower limit of the amount of S does not need to be specified.
  • the amount of S may be 0% or more than 0%. From the viewpoint of cost, it is preferably 0.0002% or more.
  • N is an element contained as an impurity that forms inclusions in steel and deteriorates toughness after hot press forming. Therefore, the amount of N is preferably 0.010% or less. It is preferably 0.008% or less, more preferably 0.005% or less. The lower limit of the amount of N does not need to be specified. The amount of N may be 0% or more than 0%. From the viewpoint of cost, it is preferably 0.0002% or more.
  • the rest are Fe and impurities.
  • the impurity refers to a component contained in raw materials such as ore and scrap, or a component mixed in the manufacturing process, which is not intentionally contained in the base steel sheet.
  • the aluminum plating layer is formed on both sides of the base steel plate.
  • the method for forming the aluminum plating layer is not particularly limited.
  • the aluminum plating layer may be formed on both sides of the base steel sheet by a hot dip galvanizing method.
  • the hot-dip galvanizing method is a method in which a base steel sheet is immersed in a molten metal bath containing mainly aluminum, and aluminum plating is applied to both surfaces of the base steel sheet.
  • the aluminum plating layer is a plating layer containing aluminum as a main component, and may contain 50% by mass or more of aluminum. Depending on the purpose, it may contain an element other than aluminum (for example, Si), or may contain impurities that are mixed in during the manufacturing process.
  • the aluminum-plated layer may contain, for example, 5% to 12% of Si (silicon) in mass%, and the balance may have a chemical composition consisting of aluminum and impurities. Further, it may contain 5% to 12% of Si (silicon) and 2% to 4% of Fe (iron) in mass%, and the balance may have a chemical composition consisting of aluminum and impurities.
  • Si is contained in the above range, deterioration of workability and corrosion resistance can be suppressed. Moreover, the thickness of the intermetallic compound layer can be reduced.
  • the thickness of the aluminum-plated layer provided in the region other than the edge of the butt-welding steel sheet is not particularly limited, and for example, the thickness is often in the range of 8 ⁇ m to 50 ⁇ m, and may be in the range of 8 ⁇ m to 35 ⁇ m. It is preferably in the range of 15 ⁇ m to 30 ⁇ m, more preferably.
  • the thickness of the aluminum-plated layer represents the average value of the thickness in the region other than the edge of the butt-welding steel plate.
  • the aluminum plating layer prevents corrosion of the steel plate for butt welding. Further, when the tailored blank is processed by hot press molding, the aluminum-plated layer suppresses the generation of scale (iron compound) due to surface oxidation even when heated to a high temperature. Further, the aluminum plating layer has a higher boiling point and melting point than the plating coating with an organic material or the plating coating with another metal material (for example, a zinc material). Therefore, when molding by hot press molding, the coating does not evaporate, so that the surface protection effect is high.
  • the aluminum plating layer can be alloyed with iron (Fe) in the base steel sheet by heating during hot dip galvanizing and hot press forming. Therefore, the aluminum-plated layer is not always formed of a single layer having a constant component composition, but includes a partially alloyed layer (alloy layer).
  • the intermetallic compound layer is a layer formed at the boundary between the base steel plate and the aluminum plating layer when aluminum plating is provided on the base steel plate. Specifically, the intermetallic compound layer is formed by the reaction of iron (Fe) of the base steel sheet with a metal containing aluminum (Al) in a molten metal bath containing aluminum as a main component.
  • the intermetallic compound layer is mainly formed of a plurality of types of compounds represented by Fe x Al y (x and y represent 1 or more).
  • the aluminum plating layer contains Si (silicon), it is formed of a plurality of kinds of compounds represented by Fe x Al y and Fe x Al y Si z (x, y, z represent 1 or more).
  • the content common to the intermetallic compound layer (IMC 1 ) formed in at least a part of the edge portion and the intermetallic compound layer (IMC 0 ) is simply referred to as an intermetallic compound layer. ..
  • the thickness of the intermetallic compound layer (IMC 0 ) formed in the region other than the edge of the butt welding steel sheet is in the range of 3 ⁇ m to 10 ⁇ m (that is, the above formula (2) is satisfied).
  • the thickness of the intermetallic compound layer (IMC 0 ) is preferably in the range of 4 ⁇ m to 8 ⁇ m.
  • the thickness of the intermetallic compound layer (IMC 1 ) is efficiently improved.
  • the thickness of the intermetallic compound layer (IMC 0 ) is 3 ⁇ m or more, the movement of the aluminum plating layer is less likely to occur.
  • the uniformity of the thickness of the aluminum plating layer is ensured by suppressing the sagging of the aluminum plating layer.
  • an intermetallic compound layer (IMC 1 ) is formed on both sides of the base steel sheet at least a part of the edge portion.
  • the aluminum plating layer may be removed or the aluminum plating layer having a reduced thickness may remain on the intermetallic compound layer (IMC 1 ) formed at the edge portion.
  • the thickness of the intermetallic compound layer (IMC 1) is greater than the thickness of the intermetallic compound layer in the region other than the edge (IMC 0).
  • the intermetallic compound layer (IMC 1 ) is formed at the edge of the planned weld.
  • the intermetallic compound layer (IMC 1 ) provided at least a part of the edge portion is not particularly limited as long as it is provided at the edge portion of the planned welding portion among the edge portions provided in the butt welding steel plate.
  • the intermetallic compound layer (IMC 1 ) may be provided at the edge of the planned welding portion in the following manners. 1) An embodiment in which the entire region is within 5% of the end face of the butt welding steel plate with respect to the length from the opposite end face to the end face, and is provided along the edge of the butt welding steel plate. 2) A part of the area within 5% of the end face of the butt welding steel plate with respect to the length from the opposite end face to the end face, and is provided along the edge of the butt welding steel plate. Aspect.
  • the aspect provided along the entire length of the edge of the butt welding steel plate.
  • the aspect is provided along only the length corresponding to the portion to be butt-welded in the total length of the edge of the butt-welding steel plate.
  • An embodiment provided in a region excluding the edge of the butt-welding steel sheet within a range of 5% or less from the end face of the butt-welding steel sheet with respect to the length from the opposite end face to the end face.
  • the intermetallic compound layer (IMC 1 ) is not formed at the edge portion that is not scheduled to be welded, and the intermetallic compound layer (IMC 0 ) may remain.
  • the edge portion that is not scheduled to be welded has the same structure as the region other than the edge portion.
  • an intermetallic compound layer (IMC 1 ) may be formed on the edge portion that is not scheduled to be welded, if necessary.
  • the edge of the planned weld represents the edge on which butt welding is performed to form a tailored blank.
  • An edge that is not planned to be welded represents an edge that is not planned to be butt welded to form a tailored blank.
  • the thickness of the intermetallic compound layer (IMC 1) is preferably in the range of 5 ⁇ m to 30 ⁇ m, preferably in the range of 8 ⁇ m to 25 ⁇ m, and more preferably in the range of 8 ⁇ m to 18 ⁇ m. ..
  • the thickness of the intermetallic compound layer (IMC 1 ) When the thickness of the intermetallic compound layer (IMC 1 ) is 5 ⁇ m or more, the corrosion resistance of the welded portion after painting becomes more excellent. On the other hand, when the thickness of the intermetallic compound layer (IMC 1 ) is 30 ⁇ m or less, the decrease in strength of the weld metal is likely to be suppressed.
  • the portion where the thickness of the intermetallic compound layer (IMC 1 ) gradually increases from the thickness of the intermetallic compound layer (IMC 0 ) is excluded from the measurement of the thickness of the intermetallic compound layer (IMC 1 ). In other words, the thickness of the intermetallic compound layer (IMC 1) represents the thickness of a portion increase from the thickness of the intermetallic compound layer (IMC 0) is saturated.
  • the thickness of the intermetallic compound layer (IMC 1) is intermetallic compound layer as a (IMC 0) (the thicknesses of / IMC 0 of IMC 1) thickness ratio to the thickness of the thickness ratio exceeds 1.
  • This thickness ratio is preferably 1.2 or more, more preferably 1.5 or more.
  • the upper limit of the thickness ratio is not particularly limited, and examples thereof include 7 or less, and 5 or less.
  • FIG. 1 is an enlarged schematic cross-sectional view showing an example of the periphery of the edge portion of the planned welding portion in the butt welding steel plate of the present disclosure.
  • FIG. 2 is an enlarged schematic cross-sectional view showing another example around the edge portion of the planned welding portion in the butt welding steel plate of the present disclosure.
  • the butt-welding steel sheet 110 has an edge portion 22 of a planned welding portion and a region 26 other than the edge portion.
  • the intermetallic compound layer (IMC 0 ) 16A is provided on the base steel plate 12, and the aluminum plating layer 14A is provided on the intermetallic compound layer (IMC 0 ) 16A.
  • the intermetallic compound layer (IMC 1 ) 16B is provided on the base steel plate 12, and the aluminum plating layer 14B is provided on the intermetallic compound layer (IMC 1 ) 16B. It is provided. The thickness of the aluminum-plated layer 14B is reduced as compared with the aluminum-plated layer 14A provided in the region 26 other than the edge portion. Further, in the butt welding steel plate 120 shown in FIG.
  • the region 26 other than the edge portion is the same as the region 26 other than the edge portion in the butt welding steel plate 110 shown in FIG.
  • the intermetallic compound layer (IMC 1 ) 16B is provided on the base steel plate 12, and the aluminum plating layer 14A is removed.
  • FIG. 4 is an enlarged cross-sectional photograph showing an example of an untreated edge portion.
  • FIG. 5 is an enlarged cross-sectional photograph showing an example of an edge portion of a planned welding portion in the butt welding steel plate of the present disclosure.
  • an intermetallic compound layer (IMC 0 ) 16C is provided on the base steel plate 12, and an aluminum plating layer 14C is provided on the intermetallic compound layer (IMC 0 ) 16C. ing. Since the edge portion shown in FIG.
  • the thickness of the intermetallic compound layer (IMC 0 ) 16C is about the same as the thickness of the intermetallic compound layer in the region other than the edge portion.
  • an intermetallic compound layer (IMC 1 ) 16B is formed on the base steel plate 12. Therefore, as shown in FIG. 5, the thickness of the intermetallic compound layer (IMC 1 ) 16B at the edge portion of the butt-welded steel sheet of the present disclosure is thicker than that of the untreated edge portion shown in FIG. You can see that. That is, from the enlarged cross-sectional photographs shown in FIGS.
  • the thickness of the intermetallic compound layer (IMC 1 ) at the edge of the planned welding portion is the thickness between the metals in the region other than the edge. It can be seen that the thickness is larger than the thickness of the compound layer (IMC 0 ).
  • the butt welding steel sheet of the present disclosure has an intermetallic compound layer (IMC 1 ) having a thickness larger than the thickness of the above-mentioned intermetallic compound layer (IMC 0 ) on both sides of the base steel sheet at least a part of the edge portion. Is formed. At the edge where the intermetallic compound layer (IMC 1 ) is formed, only the intermetallic compound layer (IMC 1 ) may be provided. Further, an aluminum plating layer having a reduced thickness may be provided on the intermetallic compound layer (IMC 1 ) as long as the mechanical strength of the weld metal does not decrease. In particular, the presence of an aluminum-plated layer in addition to the intermetallic compound layer (IMC 1 ) is permitted as long as the following formula (3) is satisfied.
  • the steel sheet for butt welding of the present disclosure has a thickness of a 1 ( ⁇ m) per side of the aluminum plating layer at the edge where the intermetallic compound layer (IMC 1 ) is formed, and one side of the intermetallic compound layer (IMC 1 ).
  • the thickness per area is b 1 ( ⁇ m) and the thickness of the base steel plate is t 0 ( ⁇ m)
  • the plate thickness represents the thickness of the base steel plate measured in a region other than the edge portion.
  • the plate thickness of the formula (3) is converted into ⁇ m and substituted. Equation (3): 0.8% ⁇ ⁇ 2 ⁇ (a 1 ( ⁇ m) + b 1 ( ⁇ m)) / t 0 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5%
  • the intermetallic compound layer on (IMC 1) 16B if it has an aluminum-plated layer 14B, a 1 indicates the thickness of the aluminum layer 14B ( ⁇ m).
  • b 1 indicates the thickness ( ⁇ m) of the intermetallic compound layer (IMC 1 ) 16B.
  • FIG. 2 when the aluminum plating layer on the intermetallic compound layer (IMC 1 ) 16B is removed (that is, when the aluminum plating layer 14B is not provided), a 1 is 0 (that is, when the aluminum plating layer 14B is not provided). ⁇ m), where b 1 indicates the thickness ( ⁇ m) of the intermetallic compound layer (IMC 1 ) 16B.
  • b 1 is synonymous with the thickness of the above-mentioned intermetallic compound layer (IMC 1 ).
  • a 1 represents the thickness of the portion excluding the portion where the thickness of the aluminum layer in the region other than the edge gradually decreases. That, a 1 represents the thickness of the portion decrease in thickness of the aluminum layer is saturated.
  • a 1 becomes 0 (zero) ( ⁇ m). However, it decreases until the aluminum plating layer disappears, and if the aluminum plating layer exists again (for example, when the aluminum plating layer exists away from the region other than the edge), the aluminum that exists again the thickness of the plating layer and a 1.
  • the value represented by the above formula (3) exceeds 3.5%, the average aluminum concentration in the weld metal (molten solidification region after welding) increases, so that soft parts that are not hardened are generated and become hot. The mechanical strength of stamped products tends to decrease.
  • the value represented by the above formula (3) is less than 0.8%, the corrosion resistance of the welded portion after painting tends to decrease.
  • the value represented by the above formula (3) is preferably in the range of 1.0% to 3.5%, more preferably in the range of 1.6% to 3.3%, and preferably in the range of 2.0% to 3.0%. The range is even more preferred.
  • “per one side” represents the measured value of the thickness on one side.
  • intermetallic compound layer (IMC 1 ) formed at the edge and the aluminum plating layer existing on the intermetallic compound layer (IMC 1 ) are on one side and satisfy the formula (3). Good. It is preferable that both sides satisfy the formula (3). Further, on the intermetallic compound layer (IMC 1), if the aluminum plating layer does not exist, it is substituted into a 1 of the formula (3) 0 (zero).
  • the thickness a 1 ( ⁇ m) per side of the aluminum plating layer and the thickness b 1 ( ⁇ m) per side of the intermetallic compound layer (IMC 1 ) can be measured by measuring the aluminum plating layer and the intermetallic compound layer (IMC 1 ) described later. The procedure may be the same as for IMC 1 ).
  • the intermetallic compound layer (IMC 1 ) formed on at least a part of the edge portion of the butt-welding steel sheet is formed on the edge portion of the planned welding portion of the butt-welding steel sheet.
  • the width of the intermetallic compound layer (IMC 1 ) formed at the edge of the planned welding portion is preferably 0.2 mm to 5.0 mm on average. When used for laser welding, it is preferably 0.6 mm to 1.5 mm. When used for plasma welding, it is preferably 1.0 mm to 4.0 mm.
  • the width of the intermetallic compound layer formed at the edge of the butt welding steel plates (IMC 1) is an average value of values obtained by measuring the width at the position of the five locations of the intermetallic compound layer (IMC 1).
  • the specific measurement method is as follows. First, five measurement samples including a cross section in which the entire width of the intermetallic compound layer (IMC 1 ) formed on the edge of the butt welding steel plate can be observed are collected. That is, the measurement sample is a metal having a length L of an intermetallic compound layer (IMC 1 ) formed in a direction along the edge of the butt-welding steel plate (in the X direction (direction in which the planned welding portion extends) shown in FIG. 1).
  • the intermetallic layer (IMC 1 ) length L) is collected from the vicinity of the central position at 5 locations divided into 5 equal parts.
  • the length L of the intermetallic compound layer (IMC 1 ) formed in the X direction is divided into five equal parts.
  • a measurement sample is collected from a position passing near the central position C along the direction of the arrow F1.
  • the steel sheet for butt welding is cut so that the cross section is exposed, embedded in resin, polished, and the cross section is enlarged with an optical microscope.
  • the distance from the edge of the steel plate for butt welding to the portion where the increase from the thickness of the intermetallic compound layer (IMC 0 ) is saturated is calculated.
  • the same measurement is performed for each sample for measurement collected, and the average value measured at five points is defined as the width of the intermetallic compound layer (IMC 1 ).
  • W shown in FIG. 1 is the width of the intermetallic compound layer (IMC 1 ) formed at the edge portion.
  • this aluminum-plated layer is the intermetallic compound layer (IMC 1 ). It may remain in the entire area above. However, since the aluminum-plated layer causes a decrease in static tensile strength, it is preferable that the residual amount is small.
  • the aluminum-plated layer on the intermetallic compound layer (IMC 1 ) is at the distance from the edge of the butt-welding steel sheet to the portion where the increase from the thickness of the intermetallic compound layer (IMC 0 ) is saturated. On the other hand, it is preferable that it remains at a rate of less than 50%.
  • the ratio of the remaining aluminum plating layer is preferably 30% or less, more preferably 10% or less.
  • the confirmation of the base steel plate, the intermetallic compound layer, and the aluminum plating layer, and the measurement of the thickness of the intermetallic compound layer and the aluminum plating layer are performed by the following methods.
  • the steel sheet for butt welding is cut so as to be exposed in the direction orthogonal to the edge (that is, the Y direction shown in FIG. 1) and embedded in the resin.
  • Polish the cross section of the embedded steel plate for butt welding is line-analyzed from the surface of the steel sheet for butt welding to the base steel sheet by an electron probe microanalyzer (FE-EPMA), and the aluminum concentration and the iron concentration are measured.
  • the aluminum concentration and the iron concentration are preferably average values measured three times.
  • the measurement conditions are an accelerating voltage of 15 kV, a beam diameter of about 100 nm, an irradiation time of 1000 ms per point, and a measurement pitch of 60 nm.
  • the measurement distance may be such that the thickness of the plating layer can be measured, and is, for example, 30 ⁇ m to 80 ⁇ m in the plate thickness direction.
  • the thickness of the base steel sheet is preferably measured with an optical microscope.
  • the region where the aluminum (Al) concentration is less than 2% by mass is determined to be the base steel sheet, and the region where the aluminum concentration is 2% by mass or more is the intermetallic compound layer. Or it is judged to be an aluminum plating layer. Further, among the intermetallic compound layer and the aluminum plating layer, a region having an iron (Fe) concentration of more than 4% by mass is determined to be an intermetallic compound layer, and a region having an iron concentration of 4% by mass or less is determined to be an aluminum plating layer.
  • the thickness of the intermetallic compound layer is the distance from the boundary between the base steel plate and the intermetallic compound layer to the boundary between the intermetallic compound layer and the aluminum plating layer.
  • the thickness of the aluminum plating layer is the distance from the boundary between the intermetallic compound layer and the aluminum plating layer to the surface of the steel sheet on which the aluminum plating layer is formed.
  • the thickness of the aluminum plating layer and the thickness of the intermetallic compound layer are linearly analyzed from the surface of the butt welding steel sheet to the surface of the base steel sheet (the boundary between the base steel sheet and the intermetallic compound layer), and specifically. , Measure as follows.
  • the thickness of the aluminum plating layer and the thickness of the intermetallic compound layer (IMC 0 ) in the region other than the edge portion are in the direction perpendicular to the end face of the planned welding portion of the butt-welding steel sheet (that is, that is, according to the above-mentioned criteria. It is an average value measured near the center position of 5 points divided into 5 equal parts in the Y direction shown in FIG. Specifically, these thicknesses are values obtained as follows. For the thickness of the aluminum plating layer, the thickness from the surface of the steel sheet having the aluminum plating layer to the intermetallic compound layer is determined in the vicinity of the center position of the five equal parts as described above.
  • the average value of the obtained values is taken as the thickness of the aluminum plating layer.
  • the measurement of the thickness of the aluminum-plated layer excludes the cross section of the portion where the thickness is gradually decreasing near the boundary between the region other than the edge portion and the edge portion.
  • the thickness of the intermetallic compound layer (IMC 0 ) is such that the intermetallic compound layer and the base steel plate are formed from the boundary between the intermetallic compound layer and the aluminum plating layer near the center positions of the five equal parts as described above. Find the thickness to the boundary. Then, the average value of the obtained values is taken as the thickness of the intermetallic compound layer.
  • the measurement of the thickness of the intermetallic compound layer (IMC 0 ) excludes the cross section of the portion where the thickness gradually increases near the boundary between the region other than the edge portion and the edge portion.
  • the thickness of the aluminum plating layer is measured from the surface of the steel sheet on which the aluminum plating layer is present to the intermetallic compound layer according to the above-mentioned criteria. However, the thickness was measured within 10% of the total width from the position where the thickness reduction was saturated to the edge of the butt welding steel sheet, and the thickness reduction was saturated. The region excluding the range within 10% from the position toward the edge side of the butt welding steel sheet is divided into three equal parts, and the measurement is performed at the central position divided into three equal parts. Then, the average value of the three measured points is used.
  • the thickness of the intermetallic compound layer (IMC 1 ) is measured from the surface of the steel sheet having the aluminum plating layer to the intermetallic compound layer according to the above-mentioned criteria.
  • the range from the position where the increase in thickness is saturated to the edge of the steel sheet for butt welding is within 10% of the edge of the steel sheet for butt welding, and the increase in thickness is saturated.
  • the region excluding the range within 10% from the position toward the edge side of the butt welding steel sheet is divided into three equal parts, and the measurement is performed at the central position divided into three equal parts. Then, the average value of the three measured points is used.
  • FIG. 1 The thickness of the intermetallic compound layer
  • the thickness of the aluminum plating layer 14B (that is, a 1 ) and the thickness of the intermetallic compound layer (IMC 1 ) (that is, b 1 ) are in the range of Y. It is the average value of the values measured in, and the range of X 1 and X 2 is excluded from the measurement.
  • an intermetallic compound layer (IMC 1 ) on at least a part of the edge portion of a steel sheet for butt welding for example, the following method can be mentioned.
  • At least a part of the edge of the butt-welding steel sheet has a step of applying a treatment by a laser gouging method to the surface of the aluminum-plated layer formed on both sides of the base steel sheet (referred to as forming method A).
  • the forming method A is a method for forming an intermetallic compound layer (IMC 1 ) as follows. First, as a steel plate before forming a tailored blank, a steel plate for butt welding cut to a desired size is prepared. Next, the surface of the aluminum-plated layer formed on both sides of the base steel sheet along the edge of the butt-welding steel sheet on a part of the edge of the butt-welding steel sheet is treated by a laser gouging method. To give. Thereby, it is a method of forming an intermetallic compound layer (IMC 1 ).
  • the surface of the aluminum-plated layer of a butt-welding steel sheet is irradiated with a laser beam to melt the butt-welding steel sheet, and the melted product is produced by the dynamic pressure of an assist gas (air, inert gas, etc.).
  • an assist gas air, inert gas, etc.
  • the assist gas only needs to efficiently disperse the melt product, and the injection nozzle shape and injection direction (upper, lower, front, rear, lateral, oblique, etc.) for injecting the assist gas, and the assist gas are injected.
  • the position to do is not particularly limited.
  • the injection nozzle shape may be appropriately selected according to the purpose.
  • the injection direction and the injection position of the assist gas may be appropriately adjusted according to the purpose.
  • a flat nozzle wider than the target gouging width is used, and injection is performed from the rear in the traveling direction of the laser beam toward the irradiation position of the laser beam.
  • the intermetallic compound layer (IMC 1 ) is formed in the portion where the edge portion of the butt-welding steel sheet is treated by the laser gouging method, which is thicker than the intermetallic compound layer (IMC 0 ).
  • An aluminum plating layer may remain on a part of the edge portion treated by the laser gouging method.
  • the assist gas is preferably injected at a range of 3.0kgf / cm 2 ⁇ 7.0kgf / cm 2.
  • the laser output is preferably in the range of 0.5 kW to 4.0 kW, and the laser scanning speed is preferably in the range of 3.0 m / min to 7.0 m / min.
  • an intermetallic compound layer (IMC 1 ) is formed on at least a part of the edge of the butt-welded steel sheet
  • the order of applying the laser gouging method to the edge of the butt-welded steel sheet is the above-mentioned forming method. It is not limited to A.
  • another preferable method for forming the intermetallic compound layer (IMC 1 ) on at least a part of the edge portion of the butt weld steel sheet for example, the following method can be mentioned.
  • a process of applying a laser gouging method to the surface of an aluminum-plated layer formed on both sides of a base steel sheet and a treatment by a laser gouging method are performed on at least a part of a region other than the edge of the butt welding steel sheet. It may have a step of cutting the steel sheet so that the applied portion is located at the edge of the steel plate for butt welding (referred to as forming method B).
  • the forming method B is, for example, the following method.
  • the aluminum-plated steel sheet is punched to prepare an aluminum-plated steel sheet cut to a desired size.
  • at least a part of the region other than the edge portion is treated by a laser gouging method on the surface of the aluminum-plated layer formed on the base steel sheet.
  • the treatment by the laser gouging method is performed so as to extend in a region other than the edge of the aluminum-plated steel sheet, for example, in one direction.
  • an intermetallic compound layer (IMC 1 ) is formed in the portion treated by the laser gouging method, for example, in a state of being extended in one direction.
  • the width of the portion of the aluminum-plated steel sheet on which the intermetallic compound layer (IMC 1 ) is formed by the laser gouging method is preferably 0.4 mm to 10 mm. ..
  • the portion where the intermetallic compound layer (IMC 1 ) is formed may be cut at a position near the center line of the portion where the intermetallic compound layer (IMC 1 ) is formed so as to have a desired width.
  • a steel plate for butt welding may be obtained by cutting at a position other than the vicinity of the center line in this portion.
  • the width of the portion where the intermetallic compound layer (IMC 1 ) formed by the above forming method A is formed is 20 from half the width of the melt-solidified region (welded metal) after the butt-welding steel plate is butt-welded. It should be% to 40% larger. Further, the width of the portion where the intermetallic compound layer (IMC 1 ) was formed before cutting in the aluminum-plated steel sheet of the butt-welded steel sheet formed as in the above forming method B was obtained by butt-welding the butt-welded steel sheet. It is preferably 20% to 40% larger than the width of the later melt-solidified region (welded metal).
  • the tailored blank of the present disclosure includes a weld metal and at least two steel plates connected to the weld metal. Then, at least two steel plate portions have an edge portion connected to the weld metal and a portion other than the edge portion. Of the at least two steel plates, at least one steel plate portion is provided with an intermetallic compound layer containing at least iron and aluminum on both sides of the base steel plate at the edge portion connected to the weld metal. In the portion other than the edge portion, an intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel plate portion in this order.
  • the thickness of the aluminum plating layer per one side of at least a part of the edge portion connected to the weld metal is a 1 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 1 ) is b 1 ⁇ m
  • the thickness of the aluminum-plated layer per surface in the portion other than the connecting edge is a 0 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 0 ) is b 0 ⁇ m.
  • Equation (1) b 1 ( ⁇ m)> b 0 ( ⁇ m) Equation (2): 3 ⁇ m ⁇ b 0 ( ⁇ m) ⁇ 10 ⁇ m Equation (3): 0.8% ⁇ ⁇ 2 ⁇ (a 1 ( ⁇ m) + b 1 ( ⁇ m)) / t 0 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5% (However, the thickness a 1 of the aluminum plating layer includes 0)
  • the tailored blank of the present disclosure has at least one butt-welded steel sheet of the present disclosure, and at least two of the butt-welded steel sheets of the present disclosure are interposed via an edge having an intermetal compound layer (IMC 1 ). It is a welded steel sheet obtained by butt welding the steel sheets for butt welding. If the tailored blank has at least one butt-welded steel sheet of the present disclosure, the tailored blank is the end face of the edge portion of one butt-welded steel sheet having an intermetallic compound layer (IMC 1 ) and the edge of another steel sheet.
  • IMC 1 intermetal compound layer
  • Tailored blank may be welded in a state of abutting the end surfaces to each other of the edges having the intermetallic compound layer in the two butt welding steel plate (IMC 1), the intermetallic compound layer in the three steel plates (IMC 1 ) May be welded in a state where the end faces of the edges are butted against each other.
  • the tailored blank of the present disclosure includes at least one steel plate for butt welding of the present disclosure, and at least two steel plates for butt welding in which the edges of the two steel plates for butt welding are arranged so as to face each other. It has a weld metal that joins the edges of steel sheets for butt welding.
  • Two or more butt-welding steel sheets for obtaining a tailored blank may be used in combination according to the purpose.
  • steel plates of the same strength class may be used, or steel plates of different strength classes may be used.
  • steel plates having the same thickness may be used, or steel plates having different thicknesses may be used.
  • steel plates having the same thickness of the intermetallic compound layer IMC 1 in the steel plate for butt welding may be used, or steel plates having different thicknesses of the IMC 1 may be used.
  • the welding method for performing butt welding is not particularly limited, and examples thereof include welding methods such as laser welding (laser beam welding), arc welding, and electron beam welding.
  • examples of the arc welding include plasma welding, TIG (Tungsten Inert Gas) welding, MIG (Metal Inert Gas) welding, MAG (Metal Active Gas) welding, and the like, and examples of suitable arc welding include plasma welding. ..
  • the welding conditions may be selected according to the desired conditions such as the thickness of the butt welding steel sheet to be used. Further, welding may be performed while supplying a filler wire, if necessary.
  • the tailored blank is preferably on the end face where the welded joint is adjacent to the portion having the intermetallic compound layer (IMC 1 ). That is, the tailored blank is formed in which the portion where the intermetallic compound layer (IMC 1 ) is formed is in contact with the end faces, and the joint portion is formed by butt welding the end faces to each other.
  • the tailored blank is a tailored blank including at least two butt-welding steel plates and a weld metal, and is for butt-welding in which the edges of at least one butt-welding steel plate of the present disclosure are arranged so as to face each other.
  • a steel plate and a welding metal provided adjacent to at least a part of the edges of at least two butt-welding steel plates that is, a welding metal for joining the edges of at least two steel plates
  • a tailored blank in which at least an intermetallic compound layer (IMC 1 ) is formed on both sides of a base steel plate on at least a part of adjacent steel plates.
  • the intermetallic compound layer (IMC 1 ) is provided on both sides of the two butt-welding steel sheets joined by the weld metal, which are located around the weld metal.
  • FIG. 6 is a schematic view showing an example of a cross section of a welded portion in the tailored blank of the present disclosure.
  • the tailored blank 200 shown in FIG. 6 is formed by butt-welding the end faces of the edges of two butt-welding steel plates 120 of the same type.
  • the tailored blank 200 includes two butt-welding steel plates 120 and a weld metal 30 for joining two butt-welding steel plates 120.
  • the two butt-welded steel sheets 120 are planned to be welded because the intermetallic compound layer (IMC 0 ) 16A and the aluminum plating layer 14A are provided on both sides of the base steel sheet 12 in the region 26 other than the edge portion, respectively.
  • IMC 0 intermetallic compound layer
  • an intermetallic compound layer (IMC 1 ) 16B is provided on both surfaces of the base steel plate 12.
  • the intermetallic compound layer (IMC 1 ) 16B is provided adjacent to the weld metal 30.
  • the tailored blank 200 shown in FIG. 6 is butt-welded through the edges of two butt-welded steel plates 120 of the same type, but the butt-welded steel plate for forming the tailored blank 200 of the present disclosure is formed. Is not limited to the aspect shown in FIG.
  • FIG. 7 is an enlarged cross-sectional photograph of the tailored blank formed through the untreated edges of the two butt-welded steel plates in the vicinity of the weld metal.
  • the arrow E indicates that ferrite is present around the edge of the butt-welding steel plate in the weld metal.
  • the tailored blank shown in FIG. 7 it is considered that the presence of ferrite is observed in the weld metal due to the concentration of aluminum mixed in a large amount from the steel sheet.
  • FIG. 7 is an enlarged cross-sectional photograph of the tailored blank formed through the untreated edges of the two butt-welded steel plates in the vicinity of the weld metal.
  • the arrow E indicates that ferrite is present around the edge of the butt-welding steel plate in the weld metal.
  • FIG. 8 is an enlarged cross-sectional photograph of the tailored blank formed in the vicinity of the weld metal of the two butt-welded steel sheets of the present disclosure formed through the edges.
  • the arrow N indicates that there is no ferrite around the edge of the butt-welded steel plate in the weld metal.
  • the tailored blank shown in FIG. 8 it is considered that the presence of ferrite is not observed because the concentration of aluminum mixed in a large amount in the weld metal is small.
  • the hot press molded product includes a weld metal and at least two steel plate portions connected to the weld metal. Then, at least two steel plate portions have an edge portion connected to the weld metal and a portion other than the edge portion. Of the at least two steel plate portions, at least one steel plate portion is provided with an intermetallic compound layer containing at least iron and aluminum on both sides of the base steel plate at the edge portion connected to the weld metal. In the portion other than the edge portion, an intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order.
  • the thickness of the aluminum plating layer per one side at least a part of the edge portion connected to the weld metal is a 2 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 2 ) is b 2 ⁇ m.
  • Equation (4) 0.8% ⁇ ⁇ 2 ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) / t 1 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5% Equation (5): 10 ⁇ m ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) (However, the thickness a 2 of the aluminum plating layer includes 0)
  • the thickness b 2 [mu] m of thickness a 2 [mu] m of the aluminum layer, and the intermetallic compound layer (IMC 2), as well as the thickness b 1 [mu] m of thickness a 1 [mu] m of the aluminum layer, and the intermetallic compound layer (IMC 1) Measure by line analysis according to the criteria of. The line analysis is performed on the edge portion connected to the weld metal from the surface portion at the edge portion to the surface of the base steel plate (the boundary between the base steel plate and the intermetallic compound layer).
  • the measurement location is the edge portion corresponding to the laser gouging position in the steel plate portion connected to the weld metal (that is, the intermetallic compound layer (IMC 1 ) in the butt-welded steel plate connected to the weld metal of the present disclosure). Measure the provided edge). Specifically, in the edge portion corresponding to the position where the laser gouging treatment is performed to connect with the weld metal, the range within 10% from the weld metal and the range within 10% of the total width from the weld metal to the portion other than the edge portion, and The region excluding the range within 10% from the boundary between the portion other than the edge portion and the edge portion is divided into three equal parts, and the treatment is performed at the central position divided into three equal parts.
  • the average value of the three measured points is used.
  • the plate thickness t 1 ⁇ m of the base steel sheet it is preferable to select and measure a portion that is less affected by hot press forming.
  • the base steel plate having a thickness of t 1 ⁇ m is preferably measured with an optical microscope.
  • the value represented by the formula (5) is preferably 12 ⁇ m or more in terms of excellent corrosion resistance of the welded portion.
  • the thickness a 2 [mu] m of the aluminum layer may be 0 (zero) [mu] m, may exceed 0 .mu.m.
  • the thickness a 2 ⁇ m of the aluminum plating layer may be 0 ⁇ m, or may exceed 0 ⁇ m.
  • the hot press-formed product of the present disclosure the weld metal, the edge portion connected to the weld metal, and the portion other than the edge portion are arranged in this order from the weld metal toward the steel plate portion. That is, the hot press molded product (hot stamp molded product) of the present disclosure is produced by hot pressing the tailored blank of the present disclosure. That is, the hot stamped product is a hot stamped product including at least two butt-welded steel plates and a weld metal, and the edges of at least one butt-welded steel plate of the present disclosure are arranged so as to face each other.
  • a butt-welded steel plate and a weld metal provided adjacent to at least a part of the edges of at least two butt-welded steel plates that is, a weld metal that joins the edges of at least two butt-welded steel plates.
  • an intermetallic compound layer (IMC 2 ) is formed on at least a part of the edge portion adjacent to the weld metal in the butt welding steel sheet adjacent to the weld metal by quenching.
  • the intermetallic compound layer (IMC 2 ) is provided on both sides of the two butt-welding steel sheets joined by the weld metal, which are located around the weld metal.
  • the hot stamped product can be manufactured as follows. First, the tailored blank is heated to a high temperature to soften the tailored blank. Then, using a mold, the softened tailored blank is molded and cooled by hot stamping and then quenched to obtain a hot stamped product having a desired shape. The hot stamp molded product is hardened by heating and cooling to obtain, for example, a molded product having a high tensile strength of about 1500 MPa or more.
  • thermoforming a heating method for hot stamping it is possible to adopt a heating method such as infrared heating, energization heating, induction heating, etc., in addition to a normal electric furnace and radiant tube furnace.
  • the aluminum-plated layer of the butt-welded steel sheet is changed to an intermetallic compound layer that provides protection against corrosion and oxidation of the butt-welded steel sheet during heating.
  • the aluminum plating layer contains silicon (Si)
  • the aluminum plating layer becomes an intermetallic compound layer, that is, an Al—Fe alloy phase, due to mutual diffusion with Fe when heated. And change to an Al—Fe—Si alloy phase.
  • the melting points of the Al—Fe alloy phase and the Al—Fe—Si alloy phase are high, 1000 ° C. or higher.
  • phase There are a plurality of types of Al—Fe phase and Al—Fe—Si phase, and when heated at a high temperature or for a long time, the phase changes to an alloy phase having a higher Fe concentration. These intermetallic compound layers prevent corrosion and oxidation of butt weld steel sheets.
  • the weld metal is caused by the intermetallic compound layer (IMC 1 ) (or the intermetallic compound layer (IMC 1 ) and the aluminum plating layer) formed on at least a part of the edge of the steel plate for butt welding. Since aluminum is appropriately mixed, it contains an alloy phase (intermetallic compound layer) similar to the above. In particular, by having the above alloy layer on the surface of the weld metal, the generation of scale on the surface of the weld metal is suppressed. As a result, the chemical conversion treatment property is improved on the surface of the weld metal, and the adhesiveness of the paint is improved. As a result, the welded portion is considered to have excellent corrosion resistance after painting.
  • the preferable state of the aluminum plating layer as a hot stamp molded product is a state in which the surface is alloyed (a state in which the surface is an intermetallic compound layer) and the Fe concentration in the alloy phase is not high. If unalloyed Al remains, only this portion is rapidly corroded, the corrosion resistance after coating is deteriorated, and the coating film swelling is extremely likely to occur, which is not preferable. On the other hand, if the Fe concentration in the alloy phase becomes too high, the corrosion resistance of the alloy phase itself deteriorates, the corrosion resistance after coating deteriorates, and the coating film swells easily. That is, the corrosion resistance of the alloy phase depends on the Al concentration in the alloy phase. Therefore, in order to improve the corrosion resistance after painting, the alloying state is controlled by the amount of Al adhered and the heating conditions.
  • the maximum temperature reached during hot stamping is not particularly limited, and is preferably 850 ° C to 1000 ° C, for example. In hot stamping, the maximum temperature reached is usually about 900 ° C. to 950 ° C. because it is necessary to heat in the austenite region.
  • a tailored blank heated to a high temperature is press-molded with a mold cooled by water cooling or the like, and at the same time, it is quenched by cooling with the mold. Further, if necessary, water may be sprayed directly onto the blank material through the gap of the mold to cool the blank material. Then, a hot stamp molded product having a desired shape can be obtained.
  • the metal structure of the base steel sheet becomes at least a part, preferably the whole, austenite single-phase structure. Then, when pressed in a die, austenite is transformed into at least one of martensite and bainite by cooling under the desired cooling conditions. Then, in the obtained hot stamped product, the metal structure of the base steel sheet becomes one of martensite, bainite, or martensite-bainite.
  • an example of the process from the production of the steel plate for butt welding to the production of the hot stamped product is as follows. First, an aluminum-plated layer is formed on both sides of the base steel sheet to obtain an aluminum-plated steel sheet. At this time, an intermetallic compound layer is formed between the base steel plate and the aluminum plating layer. Next, an intermetallic compound layer is grown by laser gouging treatment at at least a part of the edge of the aluminum-plated steel sheet. At this time, all the aluminum plating layers may be changed to intermetallic compound layers, or some aluminum plating layers may not be changed to intermetallic compound layers and may remain as aluminum plating layers.
  • the steel plate having aluminum plating on both sides of the base steel plate is wound into a coil. Next, the steel sheet wound in a coil shape is pulled out and punched to obtain a punched steel sheet.
  • the laser gouging treatment on at least a part of the edge of the aluminum-plated steel sheet may be formed in a state where the aluminum-plated steel sheet is wound into a coil and then the coiled aluminum-plated steel sheet is pulled out. Good.
  • a punching process is performed so that the laser gouging treated region becomes the edge portion of the butt welding steel sheet to obtain a punched steel sheet.
  • the laser gouging treatment on at least a part of the edge portion of the aluminum-plated steel sheet may be performed after the aluminum-plated steel sheet wound in a coil shape is pulled out and punched to form the punched steel sheet.
  • laser gouging treatment may be applied to at least a part of the edge of the punched steel sheet.
  • an intermetallic compound layer (IMC 1 ) is formed in a portion other than the edge of the punched steel sheet, for example, the regions that have been subjected to laser gouging treatment are butted.
  • the laser gouged region of the punched steel sheet may be cut so as to be the edge of the steel sheet for welding.
  • At least one punched steel sheet that has been subjected to laser gouging treatment is prepared at least a part of the edge portion of the butt welding steel sheet.
  • the number of punched steel plates may be two or more, if necessary.
  • end faces having laser gouging-treated edges are butt-welded and butt-welded to obtain a tailored blank.
  • the tailored blank is heated in a heating furnace.
  • the heated tailored blank is pressed, molded and hardened by a pair of upper and lower dies. Then, by removing it from the mold, the desired hot stamp molded product can be obtained.
  • the steel pipe includes a weld metal and a steel plate portion formed in an open tubular shape in which two peripheral edges face each other, and the two peripheral edges are connected to the weld metal.
  • the steel plate portion has at least one steel plate portion, and the at least one steel plate portion has an edge portion connected to the weld metal and a portion other than the edge portion.
  • At least one steel plate portion is provided with an intermetallic compound layer containing at least iron and aluminum on both sides of the base steel plate at the edge portion connected to the weld metal.
  • an intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order.
  • the thickness of the aluminum plating layer per one side at least a part of the edge connected to the weld metal is a 1 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 1 ) is b 1 ⁇ m
  • the thickness of the aluminum-plated layer per side of the portion other than the edge connected to the weld metal is a 0 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 0 ) is b 0 ⁇ m.
  • Equation (1) b 1 ( ⁇ m)> b 0 ( ⁇ m) Equation (2): 3 ⁇ m ⁇ b 0 ( ⁇ m) ⁇ 10 ⁇ m Equation (3): 0.8% ⁇ ⁇ 2 ⁇ (a 1 ( ⁇ m) + b 1 ( ⁇ m)) / t 0 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5% (However, the thickness a 1 of the aluminum plating layer includes 0)
  • the steel pipe includes the steel plate for butt welding of the present disclosure, and the weld metal and the portion having the edge portion provided with the intermetallic compound layer (IMC 1 ) are connected. Then, in the steel pipe of the present disclosure, the weld metal, the edge portion connected to the weld metal, and the portion other than the edge portion are arranged in this order from the weld metal toward the steel plate portion. That is, the steel pipe has at least one weld metal (that is, the weld metal that joins the edges of the open pipes of the steel plate), and is a tubular body made of the butt weld steel plate (or tailored blank) of the present disclosure adjacent to the weld metal. It has an intermetallic compound layer (IMC 1 ) on both sides of the above.
  • IMC 1 intermetallic compound layer
  • Examples of the steel pipe include aspects obtained as follows. 1) the first edge, the first intermetallic compound layer (IMC 1) provided, on the second edge, the second intermetallic compound layer welding steel plate butt provided (IMC 1) 1 Prepare a sheet. This single steel plate for butt welding is formed into a tubular shape to form an open pipe. Then, in the obtained open pipe, the end face of the edge portion provided with the first intermetallic compound layer (IMC 1 ) and the end face of the edge portion provided with the second intermetallic compound layer (IMC 1 ) are butted against each other. It may be a steel pipe obtained by welding with.
  • the end face of the edge portion of the first butt-welded steel plate provided with the second unwelded compound layer (IMC 1 ) and the first unwelded steel sheet may be a steel pipe obtained by welding in a state where the end face of the edge portion of the second butt welding steel plate provided with the intermetal compound layer (IMC 1 ) is butt-welded.
  • the open pipe may be formed by being curved in a direction parallel to the welding line in the tailored blank before forming the open pipe, or may be formed by being curved in a direction of intersection.
  • FIG. 9 is a schematic schematic view showing an example of the steel pipe of the present disclosure.
  • the steel pipe 410 shown in FIG. 9 represents an aspect formed from one steel plate for butt welding.
  • the steel pipe 410 is provided with a first intermetallic compound layer (IMC 1 ) 16D and a second intermetallic compound layer (IMC 1 ) 16E adjacent to the weld metal 30.
  • an intermetallic compound layer (IMC 1 ) is formed on both edges of the steel plate for butt welding, and the aluminum plating layer is removed.
  • a first intermetallic compound layer (IMC 1 ) 16D is formed at the first edge of the butt weld steel sheet, and a second intermetallic compound layer (IMC 1 ) 16E is formed at the second edge.
  • the steel pipe 410 uses one steel plate for butt welding as an open pipe, and has an end face of a first edge portion provided with a first intermetallic compound layer (IMC 1 ) 16D and a second intermetallic compound layer (IMC). 1 ) It is formed by welding in a state where it is abutted against the end face of the second edge portion provided with 16E.
  • FIG. 10 is a schematic schematic view showing another example of the steel pipe of the present disclosure.
  • the steel pipe 420 shown in FIG. 10 represents an aspect formed from a tailored blank having two steel plates, a first steel plate for butt welding and a second steel plate for butt welding.
  • the steel pipe 420 has a second intermetallic compound layer (IMC 1 ) 16H in the first steel plate and a first intermetallic compound layer (IMC 1 ) 16J in the second steel plate adjacent to the weld metal 30.
  • IMC 1 intermetallic compound layer
  • the tailored blank for forming the steel pipe 420 includes an end face on which the first intermetallic compound layer (IMC 1 ) 16F of the first butt-welded steel plate is formed and a first butt-welded steel plate.
  • the steel pipe 420 is curved in a direction perpendicular to the welding line of the tailored blank to form an open pipe, and includes a second intermetallic compound layer (IMC 1 ) 16H in the unwelded first butt-welded steel sheet. It is formed by welding the end face of the edge portion and the end face of the edge portion of the second steel plate for butt welding provided with the first intermetallic compound layer (IMC 1 ) 16J.
  • two or more butt-welding steel plates forming the tailored blank for forming the steel pipe may be used in combination according to the purpose.
  • Examples of the combination of two or more butt-welding steel sheets include the same combination as the steel sheet described in the above-mentioned butt-welding steel sheet for forming a tailored blank.
  • the method of forming into a tubular shape is not particularly limited, and for example, any method such as a UOE method or a bending roll method may be used.
  • the welding after forming into a tubular shape is not particularly limited, and examples thereof include electric stitch welding in which welding is performed by laser welding; plasma welding; electric resistance welding or high frequency induction heating welding.
  • the hollow hardened molded product includes a weld metal and a steel plate portion formed in an open tubular shape in which two peripheral edges face each other and to which the two peripheral edges are connected to the weld metal.
  • the steel plate portion has at least one steel plate portion, and the at least one steel plate portion has an edge portion connected to the weld metal and a portion other than the edge portion.
  • At least one steel plate portion is provided with an intermetallic compound layer containing at least iron and aluminum on both sides of the base metal steel plate at the edge portion connected to the weld metal, and the base material is provided at a portion other than the edge portion.
  • An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the steel sheet in this order. Further, the thickness of the aluminum plating layer per one side at least a part of the edge portion connected to the weld metal is a 2 ⁇ m, and the thickness of the intermetallic compound layer (IMC 2 ) is b 2 ⁇ m.
  • IMC 2 intermetallic compound layer
  • Equation (4) 0.8% ⁇ ⁇ 2 ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) / t 1 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5% Equation (5): 10 ⁇ m ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) (However, the thickness a 2 of the aluminum plating layer includes 0)
  • the hollow hardened molded product (hereinafter, may be referred to as “hollow hot stamp molded product”) is a tailored product obtained by butt welding the butt welding steel plate of the present disclosure or the butt welding steel plate of the present disclosure. It is a hollow molded product obtained by quenching a steel pipe formed from a blank.
  • the weld metal, the edge portion connected to the weld metal, and the portion other than the edge portion are arranged in this order from the weld metal toward the steel plate portion. That is, the hollow hot stamped product obtained by hot stamping the steel pipe has at least one weld metal (that is, the weld metal that joins the edges of the steel plate).
  • the hollow hot stamped product has intermetallic compound layers (IMC 2 ) on both sides of the hollow hot stamped product at the edge of the butt-welded steel plate of the present disclosure adjacent to the weld metal by quenching. ..
  • the method of the intermetallic compound layer (IMC 2) are described above That's right.
  • the total thickness is smaller than the total thickness of the thickness b 0 [mu] m of the aluminum layer thickness a 0 [mu] m and the intermetallic compound layer in the portion other than the edge (IMC 0).
  • the hollow hot stamp molded product is obtained, for example, as follows.
  • a steel pipe obtained by using the butt welding steel plate of the present disclosure is formed by a bender.
  • the steel pipe is heated by a heating furnace, energization heating, or high frequency induction heating. Since the temperature for heating the steel pipe needs to be in the austenite region, it may be, for example, 850 ° C to 1000 ° C, or 900 ° C to 950 ° C.
  • the heated steel pipe is cooled by water cooling or the like and quenched. Note that molding and quenching may be performed at the same time. This is called three-dimensional hot bending quenching (3DQ).
  • 3DQ three-dimensional hot bending quenching
  • a steel pipe is hardened by heating it, deforming it by applying a load, and immediately cooling it by water cooling or the like.
  • the desired hollow hot stamped product can be obtained.
  • the hollow hot stamped product may be used as it is as a part.
  • the application of the hollow hot stamp molded product of the present disclosure is not particularly limited, and examples thereof include various automobile members such as automobile bodies and various members of industrial machines.
  • automobile members include various pillars; reinforcements such as stabilizers, door beams, roof rails and bumpers; frames; and various parts such as arms.
  • the following steel sheets were prepared as steel sheets to be applied to the butt welding steel sheets for use in the test.
  • the prepared steel sheet is a steel sheet having a strength class of 1470 MPa after hot stamping, a quadrangle having a side of 10 cm, and a base steel sheet having a plate thickness of 1.6 mm, which is plated with aluminum.
  • the thickness of the aluminum-plated layer and the thickness of the intermetallic compound layer of this steel sheet are as shown in the area column other than the edge portion in Table 2.
  • the chemical composition of the base steel sheet used for each aluminum-plated steel sheet is as shown in Table 1.
  • the plate thickness shown in Table 2 represents the plate thickness of the base steel plate.
  • the edge portion to be welded was subjected to laser gouging treatment to obtain a steel sheet for butt welding. Specifically, laser gouging treatment was performed on both sides of the edge portion of only one of the four sides over a width of 1.5 mm and a total length of 10 cm.
  • Some aluminum-plated steel sheets were treated by laser ablation instead of laser gouging to obtain steel sheets for butt welding.
  • some steel sheets were made into steel sheets for butt welding by leaving the edges to be welded untreated.
  • Table 2 shows the thickness of the aluminum plating layer and the thickness of the intermetallic compound layer at the edge portion of each butt-welding steel sheet to be welded.
  • the formula (3) is a value obtained from the thickness of the base steel plate, the thickness of the aluminum plating layer per one side, and the thickness of the intermetallic compound layer.
  • the invention example satisfies the formula (3) on both sides.
  • butt-welded steel sheets or untreated butt-welded steel sheets that had been subjected to each treatment were prepared. Then, the end faces of the edges of the butt-welded steel sheets subjected to the above treatment were butted against each other, and butt-welding was performed by laser welding to prepare a tailored blank.
  • the conditions for laser welding were a spot diameter of ⁇ 0.9 mm, a laser output of 3.2 kW, and a laser scanning speed of 3 m / min, using a fiber laser as the oscillator without using a filler wire.
  • the prepared tailored blank was held in a furnace heated to 920 ° C. for 4 minutes, molded with a water-cooled mold, and quenched to prepare a flat plate hot stamped product.
  • the hot stamped product has a tensile strength of 1470 MPa class.
  • the thickness of the aluminum plating layer at the edge connected to the weld metal, the thickness of the intermetallic compound layer (IMC 2 ), and the aluminum plating layer and the intermetallic compound layer (IMC 2 ) were measured.
  • Table 3 shows the plate thickness t 1 of the base steel plate at the position.
  • the processing conditions for laser gouging are as follows.
  • a semiconductor laser was used as the oscillator.
  • a flat nozzle was followed from behind the laser irradiation unit, and nitrogen was injected at 5.5 kgf / cm 2 .
  • a line beam having a width of 1.5 mm and a length of 1 mm was used.
  • the laser output was adjusted appropriately at 0.6 kW to 2.1 kW and the laser scanning speed was adjusted at 3 m / min to 8 m / min. No. Taking No. 6 as an example, the laser output was 0.7 kW and the laser scanning speed was 5 m / min.
  • the front and back surfaces of the edge to be butt welded were treated. By the treatment, the aluminum plating layer of Al—Si metal was not present, and the intermetallic compound layer grew to a thickness of 17 ⁇ m.
  • the conditions for laser ablation are as follows. A Q-switched laser was used as the process by laser ablation.
  • the processing conditions are a pulse width of 60 ns, a nominal output of 300 W, a pulse energy of 30 mJ, and a laser scanning speed of 10 m / min.
  • Laser ablation is a phenomenon in which constituent substances on a solid surface are explosively released by irradiation with laser light.
  • Laser gouging is a phenomenon in which molten metal is removed by high-speed gas by irradiation with laser light.
  • test plate was 65 mm in length and 100 mm in width (the welded portion is in the center of the width).
  • the automobile parts appearance corrosion test JASO M610-92 was used to evaluate the corrosion resistance after painting under the corrosion condition after 360 cycles (120 days).
  • the ratio of red rust is defined as the red rust occurrence rate, and the following criteria are visually observed for the area excluding the periphery of the weld metal (corresponding to the area other than the edge of the butt welding steel plate), the periphery of the weld metal, and the weld metal. I went there.
  • the red rust occurrence rate is a value rounded to the nearest whole number. Up to evaluation B is allowed around the weld metal, and up to evaluation B is allowed for the weld metal.
  • C Red rust occurrence rate 51% to 75%
  • D Red rust occurrence rate 76% to 100%
  • the periphery of the weld metal represents the following.
  • the periphery of the weld metal is adjacent to the weld metal formed after welding and up to the region where the increase in the thickness of the intermetallic compound layer is saturated among the parts where the edge of the butt-welding steel plate is subjected to laser gouging treatment. Show the part.
  • the periphery of the weld metal indicates a portion adjacent to the weld metal and up to the region where the intermetallic compound layer is exposed. When untreated, the portion up to the region corresponding to the region where the increase in the thickness of the intermetallic compound layer in the laser gouging treatment is saturated is shown.
  • the thickness of the intermetallic compound layer (IMC 0 ) satisfies the range of 3 mm to 10 mm (that is, the above-mentioned range of the formula (2) is satisfied).
  • the thickness of the intermetallic compound layer (IMC 1) is greater than the thickness of the intermetallic compound layer (IMC 0) (i.e., satisfies the scope of formula (1) above).
  • the range of the above-mentioned equation (3) is satisfied. Therefore, in all regions (around the weld metal, around the weld metal, and the weld metal), the corrosion resistance and the tensile strength after painting were excellent. And these satisfy the range of the above-mentioned equations (4) and (5).

Abstract

A steel sheet in which an intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided in said order on both surfaces of a base steel sheet, and which satisfies expression (1): b1 (µm) > b0 (µm), expression (2): 3 µm ≤ b0 (µm) ≤ 10 µm, and expression (3): 0.8% ≤ {2 x (a1 (µm) + b1 (µm))/t0 (µm)} x 100 ≤ 3.5%, wherein the thickness of the aluminum plating layer and the thickness of the intermetallic compound layer (IMC0) per one surface at a part other than the edge part of the steel sheet are set as a0 µm and b0 µm, respectively, the thickness of the aluminum plating layer and the thickness of the intermetallic compound layer (IMC1) per one surface at least at a part of the edge part of the steel sheet are set as a1 µm and b1 µm, respectively, and the sheet thickness of the base steel sheet at the part other than the edge part is defined as t0 µm.

Description

鋼板、テーラードブランク、熱間プレス成形品、鋼管、及び中空状焼入れ成形品Steel plate, tailored blank, hot press molded product, steel pipe, and hollow hardened molded product
　本開示は、鋼板、テーラードブランク、熱間プレス成形品、鋼管、及び中空状焼入れ成形品に関するものである。 The present disclosure relates to steel sheets, tailored blanks, hot press molded products, steel pipes, and hollow hardened molded products.
　近年、地球環境保護の視点からＣＯ２ガス排出量削減のために、自動車分野では、自動車車体の軽量化が喫緊の課題である。それに対して高強度鋼板を適用する検討が積極的に行われている。鋼板（めっき鋼板）の強度も益々高まっている。 In recent years, in order to reduce CO 2 gas emissions from the viewpoint of protecting the global environment, weight reduction of automobile bodies has become an urgent issue in the automobile field. On the other hand, studies on applying high-strength steel sheets are being actively conducted. The strength of steel sheets (plated steel sheets) is also increasing.
　一方で、高強度化された鋼板を成形する場合、鋼板の高強度化に伴って成形性が低下する。特に引張強度が１５００ＭＰａを越える高強度鋼板は、延性に乏しいため、自動車用骨格部材の複雑な形状に対しては冷間でプレス成形することが困難であるという課題がある。 On the other hand, when molding a steel sheet with high strength, the formability decreases as the strength of the steel sheet increases. In particular, a high-strength steel sheet having a tensile strength of more than 1500 MPa has poor ductility, and therefore has a problem that it is difficult to cold press-form a complicated shape of an automobile skeleton member.
　自動車用部材を成形する技術の一つとして、熱間プレス成形（以下、「ホットスタンプ」と称する場合がある。）が注目されている。ホットスタンプは、熱間プレス用鋼板を高温に加熱し、Ａｒ３変態温度以上の温度域でプレス加工している。さらに、ホットスタンプでは、プレス成形した鋼板を金型による抜熱で急速に冷却し、プレス圧が掛かった状態で成形と同時に変態を起こさせる。それによって、ホットスタンプは、高強度でかつ形状凍結性に優れたプレス成形品を製造することができる技術である。 Hot press molding (hereinafter, may be referred to as "hot stamping") is attracting attention as one of the techniques for molding automobile members. In hot stamping, a steel sheet for hot pressing is heated to a high temperature and pressed in a temperature range equal to or higher than the Ar 3 transformation temperature. Further, in hot stamping, a press-formed steel sheet is rapidly cooled by heat removal from a die, and a transformation is caused at the same time as molding under a press pressure. Thereby, hot stamping is a technique capable of producing a press-molded product having high strength and excellent shape freezing property.
　また、自動車用部材のプレス成形品の歩留まり、および機能性を向上させるために、少なくとも２枚の突合せ溶接用鋼板の端面を突合せて、レーザ溶接、プラズマ溶接などによって接合したテーラードブランクが、プレス用素材として適用されている。テーラードブランクは、目的に応じて、複数の突合せ溶接用鋼板を接合するため、一つの部品の中で板厚および強度を自由に変化させることができるようになる。その結果、テーラードブランクを用いることにより、自動車用部材の機能性の向上および自動車用部材の部品点数削減が可能となる。また、テーラードブランクを用いてホットスタンプすることで、板厚、強度等を自由に変化させた高強度のプレス加工品を製造することができる。 Further, in order to improve the yield and functionality of press-formed products of automobile members, tailored blanks in which the end faces of at least two butt-welded steel sheets are butted and joined by laser welding, plasma welding, etc. are used for pressing. It is applied as a material. Since the tailored blank joins a plurality of butt-welded steel plates according to the purpose, the plate thickness and strength can be freely changed in one component. As a result, by using the tailored blank, it is possible to improve the functionality of the automobile member and reduce the number of parts of the automobile member. Further, by hot stamping using a tailored blank, it is possible to manufacture a high-strength stamped product in which the plate thickness, strength and the like are freely changed.
　テーラードブランクをプレス用素材として用い、ホットスタンプにより自動車用部材を成形する場合、テーラードブランクは、例えば、８００℃～１０００℃の温度域に加熱される。このため、ホットスタンプ用のテーラードブランクには、めっき沸点が高いＡｌ－Ｓｉ等のアルミニウムめっきがなされた鋼板が使用されることが多い。 When a tailored blank is used as a press material and an automobile member is molded by hot stamping, the tailored blank is heated to, for example, a temperature range of 800 ° C to 1000 ° C. For this reason, a steel plate plated with aluminum such as Al—Si, which has a high plating boiling point, is often used for the tailored blank for hot stamping.
　これまで、テーラードブランクを形成するための鋼板（すなわち、突合せ溶接用鋼板）として、例えば、アルミニウムを主体として含むアルミニウムめっきが施された鋼板が、種々検討されてきた（例えば、特許文献１～５を参照）。
　例えば、特許文献１および特許文献２では、アルミニウムめっき層を有する鋼板において、鋼板の周囲の領域では、金属間化合物層が残存し、アルミニウムめっき層が取り除かれていることが開示されている。
　また、特許文献３および特許文献４では、アルミニウムめっき層を有する鋼板を、突合せレーザ溶接して形成したホットスタンプ用テーラードブランクにおいて、溶接部が必要な強度を保持するための要件が開示されている。
　特許文献５では、アルミニウムめっきなどのめっき層を有する鋼板において、鋼板のエッジ領域をレーザアブレーション処理することが開示されている。 So far, as steel sheets for forming tailored blanks (that is, steel sheets for butt welding), for example, aluminum-plated steel sheets containing mainly aluminum have been studied in various ways (for example, Patent Documents 1 to 5). See).
For example, Patent Document 1 and Patent Document 2 disclose that in a steel sheet having an aluminum plating layer, an intermetallic compound layer remains and the aluminum plating layer is removed in a region around the steel sheet.
Further, Patent Documents 3 and 4 disclose requirements for a welded portion to maintain a required strength in a tailored blank for hot stamping formed by butt laser welding a steel sheet having an aluminum plating layer. ..
Patent Document 5 discloses that in a steel sheet having a plating layer such as aluminum plating, the edge region of the steel sheet is subjected to laser ablation treatment.
国際公開２００７／１２５１８２号International Publication No. 2007/125182 国際公開２０１５／１６２４７８号International release 2015/162478 日本国特開２０１３－２０４０９０号公報Japanese Patent Application Laid-Open No. 2013-204090 日本国特開２０１３－２２０４４５号公報Japanese Patent Application Laid-Open No. 2013-220445 国際公開２０１４／００５０４１号International Publication 2014/005041
　アルミニウムを主体として含む金属のめっきが施された鋼板は、母材鋼板上に設けられた金属間化合物層と、金属間化合物層上に設けられたアルミニウムめっき層とを有する（例えば、特許文献１～５を参照）。例えば、金属間化合物層の厚みが大きい鋼板を備えたテーラードブランクをホットスタンプして、熱間プレス成形品（以下、「ホットスタンプ成形品」と称する場合がある。）を製造した場合、溶接部以外の領域で、ホットスタンプ成形品にクラックなどが生じることがある。この現象は、硬質で脆い金属間化合物層の厚みが大きいことに起因していると考えられる。このため、ホットスタンプ成形品は、金属間化合物層の厚みが薄い鋼板を有するテーラードブランクを用いて製造されることが好ましい。 A steel sheet plated with a metal mainly containing aluminum has an intermetallic compound layer provided on the base steel sheet and an aluminum-plated layer provided on the intermetallic compound layer (for example, Patent Document 1). See ~ 5). For example, when a tailored blank provided with a steel plate having a large thickness of an intermetallic compound layer is hot stamped to produce a hot press molded product (hereinafter, may be referred to as a “hot stamp molded product”), the welded portion. Cracks or the like may occur in the hot stamped product in areas other than the above. This phenomenon is considered to be due to the large thickness of the hard and brittle intermetallic compound layer. For this reason, the hot stamped product is preferably manufactured using a tailored blank having a steel plate having a thin intermetallic compound layer.
　しかしながら、アルミニウムめっき層を有するテーラードブランクを用いたホットスタンプ成形品では、溶接部の溶接金属で破断が生じる場合があった。
　特に、特許文献１及び特許文献２には、溶接予定部のアルミニウムめっき層を取り除いて金属間化合物層を残した鋼板とし、この鋼板を突合せ溶接用鋼板とすることが開示されている。そして、この鋼板の金属間化合物層を残した領域の端面どうしを突合せた状態で突合せ溶接したテーラードブランクとし、このテーラードブランクを用いることにより、ホットスタンプ成形品での溶接金属の破断が回避できることが開示されている。 However, in a hot stamped product using a tailored blank having an aluminum plating layer, breakage may occur in the weld metal of the welded portion.
In particular, Patent Document 1 and Patent Document 2 disclose that a steel sheet is obtained by removing the aluminum plating layer of the planned welding portion to leave an intermetallic compound layer, and using this steel sheet as a steel sheet for butt welding. Then, a tailored blank is formed in which the end faces of the region of the steel sheet in which the intermetallic compound layer remains are butt-welded, and by using this tailored blank, breakage of the weld metal in the hot stamped product can be avoided. It is disclosed.
　さらに、特許文献１及び特許文献２には、ホットスタンプしたホットスタンプ成形品は、耐食性を有することが開示されている。しかし、特許文献１及び特許文献２に開示された鋼板では、ホットスタンプ成形品に塗装した後、溶接部における耐食性が未だ十分ではなく、さらなる塗装後耐食性の向上が求められていた。 Further, Patent Document 1 and Patent Document 2 disclose that the hot stamped molded product has corrosion resistance. However, in the steel sheets disclosed in Patent Document 1 and Patent Document 2, the corrosion resistance at the welded portion is not yet sufficient after being coated on the hot stamped molded product, and further improvement of the corrosion resistance after coating has been required.
　本開示の課題は、金属間化合物層の厚みが薄い鋼板を用いた突合せ溶接用鋼板において、継手の引張強度の低下が抑制され、かつ、熱間プレス成形品に塗装した後であっても、溶接部の塗装後耐食性に優れるテーラードブランクが得られる突合せ溶接用鋼板を提供するものである。 An object of the present disclosure is that in a steel sheet for butt welding using a steel sheet having a thin metal-to-metal compound layer, a decrease in tensile strength of a joint is suppressed, and even after coating on a hot press-formed product. It is an object of the present invention to provide a steel sheet for butt welding, which can obtain a tailored blank having excellent corrosion resistance after painting of a welded portion.
　本開示には、以下の態様が含まれる。 The present disclosure includes the following aspects.
＜１＞
　母材鋼板の両面に、鉄及びアルミニウムを含む金属間化合物層、及びアルミニウムめっき層が当該順で設けられた鋼板であって、
　前記鋼板の縁部以外の部分における片面あたりのアルミニウムめっき層の厚みをａ０μｍ、及び金属間化合物層（ＩＭＣ０）の厚みをｂ０μｍとし、
　前記鋼板の縁部の少なくとも一部の部分における片面あたりのアルミニウムめっき層の厚みをａ１μｍ、及び金属間化合物層（ＩＭＣ１）の厚みをｂ１μｍとし、
　前記縁部以外の部分における母材鋼板の板厚をｔ０μｍとしたとき、
　下記式（１）、下記式（２）及び下記式（３）を満たす鋼板。
　式（１）　：　ｂ１（μｍ）＞ｂ０（μｍ）
　式（２）　：　３μｍ≦ｂ０（μｍ）≦１０μｍ
　式（３）　：　０．８％≦｛２×（ａ１（μｍ）＋ｂ１（μｍ））／ｔ０（μｍ）｝×１００≦３．５％
　（ただし、アルミニウムめっき層の厚みａ１は０を含む）
＜２＞
　前記母材鋼板が、質量％で、Ｃ：０．０２％～０．５８％、Ｍｎ：０．２０％～３．００％、Ａｌ：０．００５％～０．２０％、Ｔｉ：０％～０．２０％、Ｎｂ：０％～０．２０％、Ｖ：０％～１．０％、Ｗ：０％～１．０％、Ｃｒ：０％～１．０％、Ｍｏ：０％～１．０％、Ｃｕ：０％～１．０％、Ｎｉ：０％～１．０％、Ｂ：０％～０．０１００％、Ｍｇ：０％～０．０５％、Ｃａ：０％～０．０５％、ＲＥＭ：０％～０．０５％、Ｂｉ：０％～０．０５％、Ｓｉ：０％～２．００％、Ｐ：０％～０．０３％、Ｓ：０％～０．０１０％、Ｎ：０％～０．０１０％、並びに、残部：Ｆｅおよび不純物からなる化学組成を有する＜１＞に記載の鋼板。
＜３＞
　前記縁部以外の部分での前記アルミニウムめっき層の厚みが８μｍ～５０μｍである＜１＞又は＜２＞に記載の鋼板。
＜４＞
　溶接金属と、前記溶接金属に接続する少なくとも２つの鋼板部とを備えるテーラードブランクであって、
　前記少なくとも２つの鋼板部は、前記溶接金属と接続する縁部、及び前記縁部以外の部分を有し、
　前記少なくとも２つの鋼板部のうち、少なくとも１つの鋼板部は、前記溶接金属と接続する縁部で、母材鋼板の両面に、少なくとも鉄及びアルミニウムを含む金属間化合物層が設けられており、前記縁部以外の部分で、前記母材鋼板の両面に、鉄及びアルミニウムを含む金属間化合物層、及びアルミニウムめっき層が当該順で設けられており、
　前記溶接金属と接続する縁部の少なくとも一部の部分における片面あたりのアルミニウムめっき層の厚みをａ１μｍ、及び金属間化合物層（ＩＭＣ１）の厚みをｂ１μｍとし、
　前記溶接金属と接続する縁部以外の部分における片面あたりのアルミニウムめっき層の厚みをａ０μｍ、及び金属間化合物層（ＩＭＣ０）の厚みをｂ０μｍとし、
　前記縁部以外の部分における母材鋼板の板厚をｔ０μｍとしたとき、
　下記式（１）、下記式（２）及び下記式（３）を満たすテーラードブランク。
　式（１）　：　ｂ１（μｍ）＞ｂ０（μｍ）
　式（２）　：　３μｍ≦ｂ０（μｍ）≦１０μｍ
　式（３）　：　０．８％≦｛２×（ａ１（μｍ）＋ｂ１（μｍ））／ｔ０（μｍ）｝×１００≦３．５％
　（ただし、アルミニウムめっき層の厚みａ１は０を含む）
＜５＞
　溶接金属と、前記溶接金属に接続する少なくとも２つの鋼板部とを備える熱間プレス成形品であって、
　前記少なくとも２つの鋼板部は、前記溶接金属と接続する縁部、及び前記縁部以外の部分を有し、
　前記少なくとも２つの鋼板部のうち、少なくとも１つの鋼板部は、前記溶接金属と接続する縁部で、母材鋼板の両面に、少なくとも鉄及びアルミニウムを含む金属間化合物層が設けられており、前記縁部以外の部分で、前記母材鋼板の両面に、鉄及びアルミニウムを含む金属間化合物層、及びアルミニウムめっき層が当該順で設けられており、
　前記溶接金属と接続する縁部の少なくとも一部の部分における片面あたりのアルミニウムめっき層の厚みをａ２μｍ、及び金属間化合物層（ＩＭＣ２）の厚みをｂ２μｍとし、
　前記ａ２、及び前記ｂ２の測定位置における母材鋼板の板厚をｔ１μｍとしたとき、
　下記式（４）及び下記式（５）を満たす熱間プレス成形品。
　式（４）　：　０．８％≦｛２×（ａ２（μｍ）＋ｂ２（μｍ））／ｔ１（μｍ）｝×１００≦３．５％　
　式（５）　：１０μｍ≦（ａ２（μｍ）＋ｂ２（μｍ））
　（ただし、アルミニウムめっき層の厚みａ２は０を含む）
＜６＞
　溶接金属と、周方向の２つの縁部が互いに対向するオープン管状に形成され、前記溶接金属に、前記周方向の２つの縁部が接続する鋼板部とを備える鋼管であって、
　前記鋼板部は、少なくとも１つの鋼板部を有し、前記少なくとも１つの鋼板部は、前記溶接金属と接続する縁部、及び前記縁部以外の部分を有し、
　前記少なくとも１つの鋼板部は、前記溶接金属と接続する縁部で、母材鋼板の両面に、少なくとも鉄及びアルミニウムを含む金属間化合物層が設けられており、前記縁部以外の部分で、前記母材鋼板の両面に、鉄及びアルミニウムを含む金属間化合物層、及びアルミニウムめっき層が当該順で設けられており、
　前記溶接金属と接続する縁部の少なくとも一部の部分における片面あたりのアルミニウムめっき層の厚みをａ１μｍ、及び金属間化合物層（ＩＭＣ１）の厚みをｂ１μｍとし、
　前記溶接金属と接続する縁部以外の部分における片面あたりのアルミニウムめっき層の厚みをａ０μｍ、及び金属間化合物層（ＩＭＣ０）の厚みをｂ０μｍとし、
　前記縁部以外の部分における母材鋼板の板厚をｔ０μｍとしたとき、
　下記式（１）、下記式（２）及び下記式（３）を満たす鋼管。
　式（１）　：　ｂ１（μｍ）＞ｂ０（μｍ）
　式（２）　：　３μｍ≦ｂ０（μｍ）≦１０μｍ
　式（３）　：　０．８％≦｛２×（ａ１（μｍ）＋ｂ１（μｍ））／ｔ０（μｍ）｝×１００≦３．５％
　（ただし、アルミニウムめっき層の厚みａ１は０を含む）
＜７＞
　溶接金属と、周方向の２つの縁部が互いに対向するオープン管状に形成され、前記溶接金属に、前記周方向の２つの縁部が接続する鋼板部とを備える中空状焼入れ成形品であって、
　前記鋼板部は、少なくとも１つの鋼板部を有し、前記少なくとも１つの鋼板部は、前記溶接金属と接続する縁部、及び前記縁部以外の部分を有し、
　前記少なくとも１つの鋼板部は、前記溶接金属と接続する縁部で、母材鋼板の両面に、少なくとも鉄及びアルミニウムを含む金属間化合物層が設けられており、前記縁部以外の部分で、前記母材鋼板の両面に、鉄及びアルミニウムを含む金属間化合物層、及びアルミニウムめっき層が当該順で設けられており、
　前記溶接金属と接続する縁部の少なくとも一部の部分における片面あたりのアルミニウムめっき層の厚みをａ２μｍ、及び金属間化合物層（ＩＭＣ２）の厚みをｂ２μｍとし、
　前記ａ２、及び前記ｂ２の測定位置における母材鋼板の板厚をｔ１μｍとしたとき、
　下記式（４）及び下記式（５）を満たす熱間プレス成形品。
　式（４）　：　０．８％≦｛２×（ａ２（μｍ）＋ｂ２（μｍ））／ｔ１（μｍ）｝×１００≦３．５％　
　式（５）　：１０μｍ≦（ａ２（μｍ）＋ｂ２（μｍ））
　（ただし、アルミニウムめっき層の厚みａ２は０を含む） <1>
A steel sheet in which an intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided in this order on both sides of the base steel sheet.
The thickness of the aluminum plating layer per side of the steel sheet other than the edge is a 0 μm, and the thickness of the intermetallic compound layer (IMC 0 ) is b 0 μm.
The thickness of the aluminum-plated layer per one side of at least a part of the edge of the steel sheet is a 1 μm, and the thickness of the intermetallic compound layer (IMC 1 ) is b 1 μm.
When the thickness of the base steel plate in the portion other than the edge is t 0 μm,
A steel sheet that satisfies the following formula (1), the following formula (2), and the following formula (3).
Equation (1): b 1 (μm)> b 0 (μm)
Equation (2): 3 μm ≤ b 0 (μm) ≤ 10 μm
Equation (3): 0.8% ≤ {2 × (a 1 (μm) + b 1 (μm)) / t 0 (μm)} × 100 ≦ 3.5%
(However, the thickness a 1 of the aluminum plating layer includes 0)
<2>
The base steel plate is C: 0.02% to 0.58%, Mn: 0.20% to 3.00%, Al: 0.005% to 0.20%, Ti: 0% in terms of mass%. ~ 0.20%, Nb: 0% ~ 0.20%, V: 0% ~ 1.0%, W: 0% ~ 1.0%, Cr: 0% ~ 1.0%, Mo: 0% ~ 1.0%, Cu: 0% to 1.0%, Ni: 0% to 1.0%, B: 0% to 0.0100%, Mg: 0% to 0.05%, Ca: 0% ~ 0.05%, REM: 0% to 0.05%, Bi: 0% to 0.05%, Si: 0% to 2.00%, P: 0% to 0.03%, S: 0% The steel plate according to <1>, which has a chemical composition of ~ 0.010%, N: 0% to 0.010%, and the balance: Fe and impurities.
<3>
The steel sheet according to <1> or <2>, wherein the thickness of the aluminum-plated layer at a portion other than the edge portion is 8 μm to 50 μm.
<4>
A tailored blank comprising a weld metal and at least two steel plate portions connected to the weld metal.
The at least two steel plate portions have an edge portion connected to the weld metal and a portion other than the edge portion.
Of the at least two steel plate portions, at least one steel plate portion is an edge portion connected to the weld metal, and intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate. An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in a portion other than the edge portion in this order.
The thickness of the aluminum-plated layer per one surface at least a part of the edge connected to the weld metal is a 1 μm, and the thickness of the intermetallic compound layer (IMC 1 ) is b 1 μm.
The thickness of the aluminum plating layer per one side in the portion other than the edge portion connected to the weld metal is a 0 μm, and the thickness of the intermetallic compound layer (IMC 0 ) is b 0 μm.
When the thickness of the base steel plate in the portion other than the edge is t 0 μm,
A tailored blank that satisfies the following formula (1), the following formula (2), and the following formula (3).
Equation (1): b 1 (μm)> b 0 (μm)
Equation (2): 3 μm ≤ b 0 (μm) ≤ 10 μm
Equation (3): 0.8% ≤ {2 × (a 1 (μm) + b 1 (μm)) / t 0 (μm)} × 100 ≦ 3.5%
(However, the thickness a 1 of the aluminum plating layer includes 0)
<5>
A hot press-formed product comprising a weld metal and at least two steel plate portions connected to the weld metal.
The at least two steel plate portions have an edge portion connected to the weld metal and a portion other than the edge portion.
Of the at least two steel plate portions, at least one steel plate portion is an edge portion connected to the weld metal, and intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate. An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in a portion other than the edge portion in this order.
The thickness of the aluminum-plated layer per one side at least a part of the edge connected to the weld metal is a 2 μm, and the thickness of the intermetallic compound layer (IMC 2 ) is b 2 μm.
When the a 2, and the thickness of the base steel sheet at the measurement position of the b 2 was t 1 [mu] m,
A hot press molded product that satisfies the following formula (4) and the following formula (5).
Equation (4): 0.8% ≤ {2 × (a 2 (μm) + b 2 (μm)) / t 1 (μm)} × 100 ≦ 3.5%
Equation (5): 10 μm ≦ (a 2 (μm) + b 2 (μm))
(However, the thickness a 2 of the aluminum plating layer includes 0)
<6>
A steel pipe comprising a weld metal and a steel plate portion in which two peripheral edges are formed in an open tubular shape facing each other and the weld metal is connected to the two peripheral edges.
The steel plate portion has at least one steel plate portion, and the at least one steel plate portion has an edge portion connected to the weld metal and a portion other than the edge portion.
The at least one steel plate portion is an edge portion connected to the weld metal, and intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate, and the portion other than the edge portion is the said. An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order.
The thickness of the aluminum-plated layer per one surface at least a part of the edge connected to the weld metal is a 1 μm, and the thickness of the intermetallic compound layer (IMC 1 ) is b 1 μm.
The thickness of the aluminum plating layer per one side in the portion other than the edge portion connected to the weld metal is a 0 μm, and the thickness of the intermetallic compound layer (IMC 0 ) is b 0 μm.
When the thickness of the base steel plate in the portion other than the edge is t 0 μm,
A steel pipe that satisfies the following formula (1), the following formula (2), and the following formula (3).
Equation (1): b 1 (μm)> b 0 (μm)
Equation (2): 3 μm ≤ b 0 (μm) ≤ 10 μm
Equation (3): 0.8% ≤ {2 × (a 1 (μm) + b 1 (μm)) / t 0 (μm)} × 100 ≦ 3.5%
(However, the thickness a 1 of the aluminum plating layer includes 0)
<7>
A hollow hardened molded product in which a weld metal and two peripheral edges are formed in an open tubular shape facing each other, and the weld metal is provided with a steel plate portion to which the two peripheral edges are connected. ,
The steel plate portion has at least one steel plate portion, and the at least one steel plate portion has an edge portion connected to the weld metal and a portion other than the edge portion.
The at least one steel plate portion is an edge portion connected to the weld metal, and intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate, and the portion other than the edge portion is the said. An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order.
The thickness of the aluminum plating layer per one side at least a part of the edge connected to the weld metal is a 2 μm, and the thickness of the intermetallic compound layer (IMC 2 ) is b 2 μm.
When the a 2, and the thickness of the base steel sheet at the measurement position of the b 2 was t 1 [mu] m,
A hot press molded product that satisfies the following formula (4) and the following formula (5).
Equation (4): 0.8% ≤ {2 × (a 2 (μm) + b 2 (μm)) / t 1 (μm)} × 100 ≦ 3.5%
Equation (5): 10 μm ≦ (a 2 (μm) + b 2 (μm))
(However, the thickness a 2 of the aluminum plating layer includes 0)
　本開示によれば、金属間化合物層の厚みが薄い鋼板を用いた突合せ溶接用鋼板において、継手の引張強度の低下が抑制され、かつ、熱間プレス成形品に塗装した後であっても、溶接部の塗装後耐食性に優れるテーラードブランクが得られる突合せ溶接用鋼板が提供される。 According to the present disclosure, in a steel sheet for butt welding using a steel sheet having a thin metal-to-metal compound layer, a decrease in tensile strength of the joint is suppressed, and even after coating on a hot press-formed product. Provided is a steel sheet for butt welding, which can obtain a tailored blank having excellent corrosion resistance after painting of a welded portion.
図１は、本開示の突合せ溶接用鋼板における溶接予定部の縁部周辺の一例を表す拡大概略断面図である。FIG. 1 is an enlarged schematic cross-sectional view showing an example of the periphery of the edge portion of the planned welding portion in the butt welding steel plate of the present disclosure. 図２は、本開示の突合せ溶接用鋼板における溶接予定部の縁部周辺の他の一例を表す拡大概略断面図である。FIG. 2 is an enlarged schematic cross-sectional view showing another example around the edge portion of the planned welding portion in the butt weld steel sheet of the present disclosure. 図３は、本開示の突合せ溶接用鋼板における溶接予定部の縁部周辺の他の一例を表す拡大概略斜視図である。FIG. 3 is an enlarged schematic perspective view showing another example around the edge portion of the planned welding portion in the butt weld steel sheet of the present disclosure. 図４は、未処理の縁部の一例を表す拡大断面写真である。FIG. 4 is an enlarged cross-sectional photograph showing an example of an untreated edge portion. 図５は、本開示の突合せ溶接用鋼板における溶接予定部の縁部の一例を表す拡大断面写真である。FIG. 5 is an enlarged cross-sectional photograph showing an example of an edge portion of a planned welding portion in the butt welding steel plate of the present disclosure. 図６は、本開示のテーラードブランクにおける溶接部の断面の一例を表す模式図である。FIG. 6 is a schematic view showing an example of a cross section of a welded portion in the tailored blank of the present disclosure. 図７は、２枚の突合せ溶接用鋼板における未処理の縁部を介して形成したテーラードブランクの溶接金属付近における拡大断面写真である。FIG. 7 is an enlarged cross-sectional photograph of the tailored blank formed through the untreated edges of the two butt-welded steel plates in the vicinity of the weld metal. 図８は、本開示の２枚の突合せ溶接用鋼板における溶接予定部の縁部を介して形成したテーラードブランクの溶接金属付近における拡大断面写真である。FIG. 8 is an enlarged cross-sectional photograph of the tailored blank formed in the vicinity of the weld metal of the two butt-welded steel sheets of the present disclosure formed through the edge of the planned welding portion. 図９は、本開示の鋼管の一例を表す概略模式図である。FIG. 9 is a schematic schematic view showing an example of the steel pipe of the present disclosure. 図１０は、本開示の鋼管の他の一例を表す概略模式図である。FIG. 10 is a schematic schematic view showing another example of the steel pipe of the present disclosure.
　以下、本開示の好ましい態様の一例について詳細に説明する。
　本開示の鋼板は、他の鋼板と突合せ溶接することでテーラードブランクを形成する鋼板を示し、以下において突合せ溶接用鋼板と称して説明する。
　なお、本開示において、「～」を用いて表される数値範囲は、「～」の前後に記載される数値を下限値及び上限値として含む範囲を意味する。
　本開示において、成分（元素）の含有量について、例えば、Ｃ（炭素）の含有量の場合、「Ｃ量」と表記することがある。また、他の元素の含有量についても同様に表記することがある。
　本開示において、「工程」との用語は、独立した工程だけではなく、他の工程と明確に区別できない場合であってもその工程の所期の目的が達成されれば、本用語に含まれる。 Hereinafter, an example of a preferred embodiment of the present disclosure will be described in detail.
The steel sheet of the present disclosure indicates a steel sheet that forms a tailored blank by butt welding with another steel sheet, and will be referred to as a butt welding steel sheet below.
In the present disclosure, the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
In the present disclosure, the content of the component (element) may be referred to as "C amount" in the case of the content of C (carbon), for example. In addition, the content of other elements may be described in the same manner.
In the present disclosure, the term "process" is included in this term not only as an independent process but also as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. ..
　本開示において、「母材鋼板」との用語は、アルミニウムめっきを施す前の鋼板であり、金属間化合物層及びアルミニウムめっき層が設けられる前の状態の鋼板を表す。
　本開示において、「金属間化合物層」との用語は、母材鋼板の両面に、アルミニウムめっきを施す際、母材鋼板とアルミニウムめっきとの間に形成される金属間化合物層を表す。
　本開示において、「アルミニウムめっき層」との用語は、母材鋼板上に施したアルミニウムめっきのうち、金属間化合物層を除く領域を表す。
　本開示において、突合せ溶接用鋼板の「断面」との用語は、板厚方向に切断した断面を表す。具体的には、図１において、突合せ溶接用鋼板の板厚方向をＺとし、溶接予定部が延びる方向（図１の表示面に直交する方向）をＸとする。そして、方向Ｚおよび方向Ｘにそれぞれ直交する方向を、Ｙとする。このとき、断面は、ＹＺ平面により切断した断面を意味する。なお、図１に示すＸ方向、Ｙ方向、及び、Ｚ方向は、図３に示すＸ方向、Ｙ方向、及び、Ｚ方向と同様の方向を示している。
　本開示において、突合せ溶接用鋼板の「縁部」との用語は、突合せ溶接用鋼板の周囲に位置している領域であって、最大となる場合で、突合せ溶接用鋼板としての鋼板の端縁から５ｍｍ以内の範囲の領域を表す。
　本開示において、突合せ溶接用鋼板の「端縁」とは、突合せ溶接用鋼板の板厚方向で対向する側の面（つまり、鋼板の表面）と、端面とが接する位置を表す。
　本開示において、突合せ溶接用鋼板の「端面」との用語は、板厚方向側で対向する面の間で、板厚方向の面が露出している面を表す。
　本開示において、突合せ溶接用鋼板の「縁部以外の部分」及び「縁部以外の領域」との用語は、突合せ溶接用鋼板としての鋼板の縁部を除く領域を表す。すなわち、「縁部以外の部分」及び「縁部以外の領域」は、突合せ溶接用鋼板の中央部を表し、最小となる場合で、突合せ溶接用鋼板の対向する幅（つまり、対向する端面から端面までの長さ）から、５ｍｍ×２を除いた範囲の領域を占めている。
　本開示において、「溶接部」との用語は、溶接金属、およびその周辺の金属間化合物層の厚みの増加が飽和している部分を含む領域を表す。 In the present disclosure, the term "base steel sheet" refers to a steel sheet before aluminum plating, and represents a steel sheet in a state before the intermetallic compound layer and the aluminum plating layer are provided.
In the present disclosure, the term "intermetallic compound layer" refers to an intermetallic compound layer formed between the base steel sheet and the aluminum plating when aluminum plating is applied to both surfaces of the base steel sheet.
In the present disclosure, the term "aluminum plating layer" refers to a region of aluminum plating applied on a base steel sheet excluding an intermetallic compound layer.
In the present disclosure, the term "cross section" of a steel sheet for butt welding refers to a cross section cut in the plate thickness direction. Specifically, in FIG. 1, the plate thickness direction of the butt-welding steel plate is Z, and the direction in which the planned welding portion extends (the direction orthogonal to the display surface in FIG. 1) is X. Then, the direction orthogonal to the direction Z and the direction X is defined as Y. At this time, the cross section means a cross section cut by the YZ plane. The X, Y, and Z directions shown in FIG. 1 indicate the same directions as the X, Y, and Z directions shown in FIG.
In the present disclosure, the term "edge" of a steel sheet for butt welding is a region located around the steel sheet for butt welding, which is the maximum, and is the edge of the steel sheet as a steel sheet for butt welding. Represents an area within 5 mm from.
In the present disclosure, the "edge" of the butt-welding steel sheet represents a position where the end face is in contact with the surface of the butt-welding steel sheet facing in the plate thickness direction (that is, the surface of the steel sheet).
In the present disclosure, the term "end face" of a steel sheet for butt welding refers to a surface in which the surface in the plate thickness direction is exposed between the surfaces facing each other on the plate thickness direction side.
In the present disclosure, the terms "a portion other than the edge portion" and "a region other than the edge portion" of the butt-welding steel sheet refer to a region excluding the edge portion of the steel sheet as a butt-welding steel sheet. That is, the "part other than the edge portion" and the "region other than the edge portion" represent the central portion of the butt welding steel plate, and in the minimum case, the opposite width of the butt welding steel plate (that is, from the facing end faces). It occupies the area excluding 5 mm × 2 from the length to the end face).
In the present disclosure, the term "welded portion" refers to a region including a weld metal and a portion around which the increase in thickness of the intermetallic compound layer is saturated.
＜突合せ溶接用鋼板＞
　本開示の突合せ溶接用鋼板は、母材鋼板の両面に、鉄及びアルミニウムを含む金属間化合物層、及びアルミニウムめっき層が当該順で設けられている。すなわち、本開示の突合せ溶接用鋼板は、このようなアルミニウムめっき鋼板から形成されるものである。
　また、本開示の突合せ溶接用鋼板は、前記突合せ溶接用鋼板の縁部以外の部分における片面あたりのアルミニウムめっき層の厚みをａ０μｍ、及び金属間化合物層（ＩＭＣ０）の厚みをｂ０μｍとし、前記突合せ溶接用鋼板の縁部の少なくとも一部の部分における片面あたりのアルミニウムめっき層の厚みをａ１μｍ、及び金属間化合物層（ＩＭＣ１）の厚みをｂ１μｍとし、前記縁部以外の部分における母材鋼板の板厚をｔ０μｍとしたとき、下記式（１）、下記式（２）及び下記式（３）を満たす（ただし、アルミニウムめっき層の厚みａ１は０を含む）。
　式（１）　：　ｂ１（μｍ）＞ｂ０（μｍ）
　式（２）　：　３μｍ≦ｂ０（μｍ）≦１０μｍ
　式（３）　：　０．８％≦｛２×（ａ１（μｍ）＋ｂ１（μｍ））／ｔ０（μｍ）｝×１００≦３．５％ <Steel sheet for butt welding>
In the butt welding steel sheet of the present disclosure, an intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order. That is, the butt welding steel sheet of the present disclosure is formed from such an aluminum-plated steel sheet.
Further, in the butt welding steel sheet of the present disclosure, the thickness of the aluminum plating layer per one side in the portion other than the edge of the butt welding steel sheet is a 0 μm, and the thickness of the intermetallic compound layer (IMC 0 ) is b 0. The thickness of the aluminum-plated layer per one side of at least a part of the edge of the butt-welding steel sheet is a 1 μm, and the thickness of the intermetallic compound layer (IMC 1 ) is b 1 μm. when the thickness of the base material steel plate at a portion other than the part was t 0 [mu] m, the following formula (1) (2) and the following formula satisfies the (3) (provided that the thickness a 1 of the aluminum plating layer 0 including).
Equation (1): b 1 (μm)> b 0 (μm)
Equation (2): 3 μm ≤ b 0 (μm) ≤ 10 μm
Equation (3): 0.8% ≤ {2 × (a 1 (μm) + b 1 (μm)) / t 0 (μm)} × 100 ≦ 3.5%
　つまり、本開示の突合せ溶接用鋼板として適用されるアルミニウムめっき鋼板は、母材鋼板と、母材鋼板の両面に設けられたアルミニウムめっき層とを有する。また、母材鋼板とアルミニウムめっき層との間には、鉄及びアルミニウムを含む金属間化合物層（ＩＭＣ０）が設けられている。
　さらに、突合せ溶接用鋼板の縁部の少なくとも一部に、前記母材鋼板の両面上に設けられた、前記金属間化合物層（ＩＭＣ１）を有している。この金属間化合物層（ＩＭＣ１）の厚みは、縁部以外の領域における金属間化合物層（ＩＭＣ０）の厚みよりも大きい（すなわち、上記式（１）を満足する。）。
　また、突合せ溶接用鋼板の縁部以外の領域での金属間化合物層（ＩＭＣ０）の厚みが３μｍ～１０μｍである（すなわち、上記式（２）を満足する。）。
　そして、金属間化合物層（ＩＭＣ１）が形成されている縁部で、上記式（３）の関係を満足する。上記式（３）中、母材鋼板の板厚ｔ０はμｍに換算した値である。金属間化合物層（ＩＭＣ１）上にアルミニウムめっき層が存在しない場合、ａ１は０（ゼロ）μｍとなる。
　なお、突合せ溶接用鋼板の形状は特に限定されるものではない。 That is, the aluminum-plated steel sheet applied as the butt-welding steel sheet of the present disclosure has a base steel sheet and aluminum-plated layers provided on both sides of the base steel sheet. Further, an intermetallic compound layer (IMC 0 ) containing iron and aluminum is provided between the base steel plate and the aluminum plating layer.
Further, at least a part of the edge portion of the butt welding steel plate has the intermetallic compound layer (IMC 1 ) provided on both surfaces of the base steel plate. The intermetallic compound layer (IMC 1) thickness is greater than the thickness of the intermetallic compound layer in the region other than the edge (IMC 0) (i.e., to satisfy the above equation (1).).
Further, the thickness of the intermetallic compound layer (IMC 0 ) in the region other than the edge of the butt welding steel sheet is 3 μm to 10 μm (that is, the above formula (2) is satisfied).
Then, the relationship of the above formula (3) is satisfied at the edge portion where the intermetallic compound layer (IMC 1 ) is formed. In the above formula (3), the plate thickness t 0 of the base steel plate is a value converted to μm. When there is no aluminum plating layer on the intermetallic compound layer (IMC 1 ), a 1 is 0 (zero) μm.
The shape of the steel plate for butt welding is not particularly limited.
　従来、アルミニウムめっきが施された鋼板を突合せ溶接用鋼板として適用し、この突合せ溶接用鋼板の縁部の端面どうしを突合せ溶接したテーラードブランクをホットスタンプして得られたホットスタンプ成形品が知られている（例えば、特許文献１～５を参照）。例えば、金属間化合物層の厚みが厚すぎる鋼板を突合せ溶接用鋼板として用い、テーラードブランクを得た後、ホットスタンプ成形品を得た場合、溶接部以外の領域で、アルミニウムめっき層および金属間化合物層にクラック及び欠落が発生することがある。金属間化合物層は、硬くて脆い。そのため、母材鋼板に存在する厚すぎる金属間化合物層が、ホットスタンプ成形時の負荷に耐え切れず、その結果として、クラック及び欠落が発生すると考えられる。クラック及び欠落は、母材鋼板まで伝播してしまうと、母材鋼板の耐食性が低下する。したがって、溶接部以外の領域では、金属間化合物層の厚みが厚すぎないことが好ましい。 Conventionally, a hot stamped product obtained by applying a steel plate plated with aluminum as a steel plate for butt welding and hot stamping a tailored blank obtained by butt welding the end faces of the edges of the steel plate for butt welding is known. (See, for example, Patent Documents 1 to 5). For example, when a steel plate with an excessively thick intermetallic compound layer is used as a steel plate for butt welding to obtain a tailored blank and then a hot stamped product is obtained, the aluminum plating layer and the intermetallic compound are formed in areas other than the welded portion. Cracks and chips may occur in the layer. The intermetallic compound layer is hard and brittle. Therefore, it is considered that the too thick intermetallic compound layer existing in the base steel sheet cannot withstand the load during hot stamping, and as a result, cracks and chips occur. If the cracks and chips propagate to the base steel sheet, the corrosion resistance of the base steel sheet is lowered. Therefore, it is preferable that the thickness of the intermetallic compound layer is not too thick in the region other than the welded portion.
　一方、金属間化合物層の厚みが薄すぎる場合、金属間化合物層と、アルミニウムめっき層との界面粗度が低下しやすくなる。この界面粗度が低下すると、突合せ溶接及びホットスタンプによる加熱で溶融したアルミニウムめっき層のアルミニウム成分が移動しやすくなる。溶融したアルミニウムめっき層のアルミニウム成分が移動すると、ホットスタンプでは、アルミニウムめっき層の垂れが生じてしまい、厚みの均一性が低下する。また、突合せ溶接では、溶接金属中にアルミニウムめっき層に起因するアルミニウムが多量に混入しやすくなる。そのため、金属間化合物層の厚みは薄すぎないことが好ましい。 On the other hand, if the thickness of the intermetallic compound layer is too thin, the interfacial roughness between the intermetallic compound layer and the aluminum plating layer tends to decrease. When this interfacial roughness is lowered, the aluminum component of the aluminum plating layer melted by butt welding and heating by hot stamping becomes easy to move. When the aluminum component of the molten aluminum plating layer moves, the aluminum plating layer hangs down in hot stamping, and the uniformity of the thickness decreases. Further, in butt welding, a large amount of aluminum due to the aluminum plating layer is likely to be mixed in the weld metal. Therefore, it is preferable that the thickness of the intermetallic compound layer is not too thin.
　突合せ溶接によって、アルミニウムが溶接金属中に多量に混入したテーラードブランクを用いて、ホットスタンプした場合、溶接金属で破断が起き、溶接強度が低下する場合があった。これは、アルミニウムの濃度が高くなった溶接金属では、フェライトの生成により焼き入れ性が低下し、ホットスタンプ後も十分な継手強度が得られないことに起因していると考えられる。 When hot stamping was performed using a tailored blank in which a large amount of aluminum was mixed in the weld metal by butt welding, the weld metal may break and the welding strength may decrease. It is considered that this is because in the weld metal having a high concentration of aluminum, the hardenability is lowered due to the formation of ferrite, and sufficient joint strength cannot be obtained even after hot stamping.
　溶接金属の破断を回避する点で、特に、特許文献１及び特許文献２には、前述のように、溶接される溶接予定部のアルミニウムめっき層を取り除き、金属間化合物層を残存させた突合せ溶接用鋼板とし、この突合せ溶接用鋼板の溶接予定部を突合せ溶接したテーラードブランクが開示されている。そして、このテーラードブランクを用いたホットスタンプ成形品では、溶接強度の低下が抑制され得る。 In particular, in Patent Document 1 and Patent Document 2, in order to avoid breakage of the weld metal, as described above, butt welding in which the aluminum plating layer of the welded portion to be welded is removed and the intermetal compound layer remains. A tailored blank is disclosed in which a steel plate for butt welding is used and a planned welding portion of the steel plate for butt welding is butt welded. Then, in the hot stamp molded product using this tailored blank, the decrease in welding strength can be suppressed.
　特許文献１及び特許文献２に開示された突合せ溶接用鋼板は、母材鋼板にアルミニウムめっき（Ａｌ－Ｓｉ金属のめっき）層が設けられており、母材鋼板とアルミニウムめっき層との間に金属間化合物層が形成されている。金属間化合物層は比較的脆弱であるので、金属間化合物層の成長を制限するために、抑制剤が溶融金属浴に添加される。そして、特許文献１に開示された突合せ溶接用鋼板は、例えば、アルミニウムめっき層が２０μｍと厚いのに対し、金属間化合物層は５μｍと薄い。 The butt-welding steel sheets disclosed in Patent Documents 1 and 2 have an aluminum plating (Al—Si metal plating) layer provided on the base steel sheet, and a metal is provided between the base steel sheet and the aluminum plating layer. An inter-compound layer is formed. Since the intermetallic compound layer is relatively fragile, an inhibitor is added to the molten metal bath to limit the growth of the intermetallic compound layer. In the butt welding steel sheet disclosed in Patent Document 1, for example, the aluminum plating layer is as thick as 20 μm, while the intermetallic compound layer is as thin as 5 μm.
　また、特許文献１及び特許文献２に開示された突合せ溶接用鋼板では、テーラードブランクの製造の前に、突合せ溶接用鋼板の溶接予定部に対し、ブラシ、又はレーザアブレーションにより、アルミニウムめっき層を取り除き、厚みの薄い金属間化合物層を残存させる。その結果、金属間化合物層の厚みが薄いことに起因して、溶接部における塗装後の耐食性が劣位となる。また、金属間化合物層の厚みが薄いため、溶接金属に混入されるアルミニウム量が少ない。そのため、特許文献１及び特許文献２に開示された突合せ溶接用鋼板では、ホットスタンプする場合に、高温に加熱されることで、溶接金属の表面でスケール（鉄の化合物）が発生しやすい。その結果、ホットスタンプ成形品に塗装した場合に、塗料の付着性が低下し、溶接部における塗装後の耐食性が劣位となる。 Further, in the butt-welded steel sheets disclosed in Patent Documents 1 and 2, the aluminum plating layer is removed from the planned welded portion of the butt-welded steel sheet by a brush or laser ablation before the tailored blank is manufactured. , A thin intermetallic compound layer remains. As a result, the corrosion resistance of the welded portion after painting becomes inferior due to the thin thickness of the intermetallic compound layer. Further, since the thickness of the intermetallic compound layer is thin, the amount of aluminum mixed in the weld metal is small. Therefore, in the butt welding steel sheets disclosed in Patent Document 1 and Patent Document 2, scale (iron compound) is likely to be generated on the surface of the weld metal by being heated to a high temperature at the time of hot stamping. As a result, when the hot stamp molded product is painted, the adhesiveness of the paint is lowered, and the corrosion resistance after painting at the welded portion is inferior.
　これに対し、本開示の突合せ溶接用鋼板は、突合せ溶接用鋼板の縁部の少なくとも一部に、母材鋼板の両面上に少なくとも金属間化合物層（ＩＭＣ１）が形成されている。そして、金属間化合物層（ＩＭＣ１）の厚みが、縁部以外の領域に形成されている金属間化合物層（ＩＭＣ０）の厚みよりも厚い。そのため、本開示の突合せ溶接用鋼板は、縁部の少なくとも一部に形成されている金属間化合物層（ＩＭＣ１）の厚みに起因して、ホットスタンプ成形品に塗装した後であっても、溶接部の耐食性に優れていると考えられる。
　また、本開示の突合せ溶接用鋼板は、鋼板の縁部の少なくとも一部に形成された厚みの大きい金属間化合物層（ＩＭＣ１）を有するため、突合せ溶接した後の溶接金属中に、アルミニウムが適度に混入される。このため、溶接金属の表面でスケールの発生が抑制されることで、化成処理性が向上し、塗料の付着性が向上する。その結果として、本開示の突合せ溶接用鋼板は、ホットスタンプ成形品に塗装した後であっても、溶接部の塗装後耐食性に優れていると考えられる。 On the other hand, in the butt welding steel sheet of the present disclosure, at least an intermetallic compound layer (IMC 1 ) is formed on both sides of the base steel sheet at least a part of the edge portion of the butt welding steel sheet. Then, the thickness of the intermetallic compound layer (IMC 1) is thicker than the thickness of the intermetallic compound layer formed in a region other than the edge (IMC 0). Therefore, due to the thickness of the intermetallic compound layer (IMC 1 ) formed in at least a part of the edge portion, the butt weld steel sheet of the present disclosure is formed even after being coated on a hot stamped product. It is considered that the welded part has excellent corrosion resistance.
Further, since the steel sheet for butt welding of the present disclosure has a thick intermetallic compound layer (IMC 1 ) formed at least a part of the edge of the steel sheet, aluminum is contained in the weld metal after butt welding. It is mixed moderately. Therefore, the generation of scale is suppressed on the surface of the weld metal, so that the chemical conversion treatment property is improved and the adhesiveness of the paint is improved. As a result, it is considered that the steel sheet for butt welding of the present disclosure is excellent in corrosion resistance after coating of the welded portion even after coating on the hot stamped molded product.
　本開示の突合せ溶接用鋼板は、鋼板の縁部の溶接予定部に形成された厚みの厚い金属間化合物層（ＩＭＣ１）上に、アルミニウムめっき層が存在しないか、または厚みが低減されたアルミニウムめっき層が存在している。そのため、本開示の突合せ溶接用鋼板は、金属間化合物層（ＩＭＣ１）を有する縁部の端面どうしを突合せて溶接した場合に、溶接金属中に、アルミニウムめっき層に起因する多量のアルミニウムの混入が抑制される。 The butt-welded steel sheet of the present disclosure is made of aluminum having no aluminum plating layer or a reduced thickness on a thick intermetallic compound layer (IMC 1 ) formed at a planned welding portion at the edge of the steel sheet. There is a plating layer. Therefore, in the butt-welding steel sheet of the present disclosure, when the end faces of the edges having the intermetallic compound layer (IMC 1 ) are butt-welded and welded, a large amount of aluminum is mixed in the weld metal due to the aluminum plating layer. Is suppressed.
　さらに、金属間化合物層（ＩＭＣ１）の厚みが、金属間化合物層（ＩＭＣ０）の厚みよりも大きいため、縁部以外の領域に形成されているアルミニウムめっき層は、突合せ溶接時に溶融して移動することが抑制される。このため、溶接金属に対して混入するアルミニウムの量が抑制される。つまり、アルミニウムめっき層に起因するアルミニウムが適度な量で溶接金属に混入する。それによって、溶接金属では焼き入れ性の低下が抑制されるため、継手の機械的強度が確保され得る。また、縁部以外の領域では、金属間化合物層（ＩＭＣ０）の厚みが薄いために、ホットスタンプ成形時のアルミニウムめっき層及び金属間化合物層（ＩＭＣ０）のクラックおよび欠落が抑制されている。その結果として、ホットスタンプ成形品の縁部以外の領域における耐食性低下が抑制される。 Further, the thickness of the intermetallic compound layer (IMC 1) is larger than the thickness of the intermetallic compound layer (IMC 0), aluminum-plated layer is formed in a region other than the edge, to melt at butt welding Movement is suppressed. Therefore, the amount of aluminum mixed in the weld metal is suppressed. That is, an appropriate amount of aluminum due to the aluminum plating layer is mixed with the weld metal. As a result, the weld metal suppresses the decrease in hardenability, so that the mechanical strength of the joint can be ensured. Further, in the region other than the edge portion, since the thickness of the intermetallic compound layer (IMC 0 ) is thin, cracks and omissions of the aluminum plating layer and the intermetallic compound layer (IMC 0 ) during hot stamping are suppressed. .. As a result, the deterioration of corrosion resistance in the region other than the edge of the hot stamped product is suppressed.
　そして、本開示の突合せ溶接用鋼板は、前述の式（３）の数値範囲が０．８％～３．５％である。式（３）の数値がこの範囲であることで、溶接金属中にアルミニウムが適度に混入される。このため、ホットスタンプ成形品の機械的強度低下が抑制されるとともに、塗装後の耐食性低下が抑制される。 The butt welding steel sheet of the present disclosure has a numerical range of 0.8% to 3.5% in the above-mentioned formula (3). When the numerical value of the formula (3) is in this range, aluminum is appropriately mixed in the weld metal. Therefore, the decrease in mechanical strength of the hot stamped molded product is suppressed, and the decrease in corrosion resistance after painting is suppressed.
［母材鋼板］
　母材鋼板は、アルミニウムめっきを施す前の鋼板である。母材鋼板は、通常の方法により得られたものであればよく、特に限定されるものではない。母材鋼板は熱延鋼板または冷延鋼板のいずれでもよい。また、母材鋼板の厚みは目的に応じた厚みとすればよく、特に限定されるものではない。例えば、母材鋼板の板厚は、アルミニウムめっき層を設けた後の鋼板全体の板厚として、０．８ｍｍ～４ｍｍとなるような板厚が挙げられ、さらに、１ｍｍ～３ｍｍとなるような板厚が挙げられる。 [Base steel plate]
The base steel sheet is a steel sheet before aluminum plating. The base steel sheet may be obtained by a usual method and is not particularly limited. The base steel plate may be either a hot-rolled steel plate or a cold-rolled steel plate. Further, the thickness of the base steel sheet may be set according to the purpose, and is not particularly limited. For example, the thickness of the base steel sheet is such that the total thickness of the steel sheet after the aluminum plating layer is provided is 0.8 mm to 4 mm, and further, the thickness is 1 mm to 3 mm. The thickness can be mentioned.
　母材鋼板の一例としては、例えば、高い機械的強度（例えば、引張強さ、降伏点、伸び、絞り、硬さ、衝撃値、疲れ強さなどの機械的な変形及び破壊に関する諸性質を意味する。）を有するように形成された鋼板を使用することがよい。 As an example of the base steel sheet, it means various properties related to mechanical deformation and fracture such as high mechanical strength (for example, tensile strength, yield point, elongation, drawing, hardness, impact value, fatigue strength, etc.). It is preferable to use a steel plate formed so as to have.
　母材鋼板の好ましい化学組成の一例としては、例えば、以下の化学組成が挙げられる。
　質量％で、Ｃ：０．０２％～０．５８％、Ｍｎ：０．２０％～３．００％、Ａｌ：０．００５％～０．２０％、Ｔｉ：０％～０．２０％、Ｎｂ：０％～０．２０％、Ｖ：０％～１．０％、Ｗ：０％～１．０％、Ｃｒ：０％～１．０％、Ｍｏ：０％～１．０％、Ｃｕ：０％～１．０％、Ｎｉ：０％～１．０％、Ｂ：０％～０．０１００％、Ｍｇ：０％～０．０５％、Ｃａ：０％～０．０５％、ＲＥＭ：０％～０．０５％、Ｂｉ：０％～０．０５％、Ｓｉ：０％～２．００％、Ｐ：０．０３％以下、Ｓ：０．０１０％以下、Ｎ：０．０１０％以下、並びに残部：Ｆｅおよび不純物からなる化学組成を有する。
　なお、以下、成分（元素）の含有量を示す「％」は、「質量％」を意味する。 Examples of the preferable chemical composition of the base steel sheet include the following chemical compositions.
By mass%, C: 0.02% to 0.58%, Mn: 0.20% to 3.00%, Al: 0.005% to 0.20%, Ti: 0% to 0.20%, Nb: 0% to 0.20%, V: 0% to 1.0%, W: 0% to 1.0%, Cr: 0% to 1.0%, Mo: 0% to 1.0%, Cu: 0% to 1.0%, Ni: 0% to 1.0%, B: 0% to 0.0100%, Mg: 0% to 0.05%, Ca: 0% to 0.05%, REM: 0% to 0.05%, Bi: 0% to 0.05%, Si: 0% to 2.00%, P: 0.03% or less, S: 0.010% or less, N: 0. It has a chemical composition of 010% or less, and the balance: Fe and impurities.
Hereinafter, "%" indicating the content of the component (element) means "mass%".
（Ｃ：０．０２％～０．５８％）
　Ｃは、母材鋼板の焼入れ性を高め、かつ焼入れ後強度を主に決定する重要な元素である。さらにＡ３点を下げ、焼入れ処理温度の低温化を促進する元素である。Ｃ量が０．０２％未満では、その効果は十分ではない場合がある。したがって、Ｃ量は０．０２％以上とすることがよい。一方、Ｃ量が０．５８％を超えると、焼入れ部の靭性劣化が著しくなる。したがって、Ｃ量は０．５８％以下とすることがよい。好ましくは０．４５％以下である。 (C: 0.02% to 0.58%)
C is an important element that enhances the hardenability of the base steel sheet and mainly determines the strength after quenching. Further lowering the three points A, it is an element which promotes lowering the quenching temperature. If the amount of C is less than 0.02%, the effect may not be sufficient. Therefore, the amount of C is preferably 0.02% or more. On the other hand, when the amount of C exceeds 0.58%, the toughness of the hardened portion is significantly deteriorated. Therefore, the amount of C is preferably 0.58% or less. It is preferably 0.45% or less.
（Ｍｎ：０．２０％～３．００％）
　Ｍｎは、母材鋼板の焼入れ性を高め、かつ焼入れ後強度を安定して確保するために、非常に効果のある元素である。Ｍｎ量が０．２０％未満では、その効果は十分ではない場合がある。したがって、Ｍｎ量は０．２０％以上とすることがよい。好ましくは０．８０％以上である。一方、Ｍｎ量が３．００％を超えると、その効果は飽和するばかりか、却って焼入れ後における安定した強度の確保が困難となる場合がある。したがって、Ｍｎ量は３．００％以下とすることがよい。好ましくは２．４０％以下である。 (Mn: 0.20% to 3.00%)
Mn is a very effective element for enhancing the hardenability of the base steel sheet and stably securing the strength after quenching. If the amount of Mn is less than 0.20%, the effect may not be sufficient. Therefore, the amount of Mn is preferably 0.20% or more. It is preferably 0.80% or more. On the other hand, if the amount of Mn exceeds 3.00%, not only the effect is saturated, but also it may be difficult to secure stable strength after quenching. Therefore, the amount of Mn is preferably 3.00% or less. It is preferably 2.40% or less.
（Ａｌ：０．００５％～０．２０％）
　Ａｌは、脱酸元素として機能する。また、Ａｌは、母材鋼板の機械的強度に悪影響を及ぼす酸化物系介在物を低減する作用を有する。Ａｌ量が０．００５％未満では、上記作用による効果を得ることが困難である場合がある。したがって、Ａｌ量は０．００５％以上とすることがよい。一方、Ａｌ量が０．２０％超では、上記作用による効果は飽和して、コスト的に不利になる。したがって、Ａｌ量は０．２０％以下とすることがよい。 (Al: 0.005% to 0.20%)
Al functions as a deoxidizing element. In addition, Al has an effect of reducing oxide-based inclusions that adversely affect the mechanical strength of the base steel sheet. If the amount of Al is less than 0.005%, it may be difficult to obtain the effect of the above action. Therefore, the amount of Al is preferably 0.005% or more. On the other hand, if the amount of Al exceeds 0.20%, the effect of the above action is saturated, which is disadvantageous in terms of cost. Therefore, the amount of Al is preferably 0.20% or less.
（Ｔｉ：０％～０．２０％、Ｎｂ：０％～０．２０％、Ｖ：０％～１．０％、Ｗ：０％～１．０％）
　Ｔｉ、Ｎｂ、Ｖ、およびＷは、アルミニウムめっき層および母材鋼板における、ＦｅおよびＡｌの相互拡散を促進する元素である。したがって、Ｔｉ、Ｎｂ、Ｖ、およびＷのうちの少なくとも１種を母材鋼板に含有させてもよい。しかし、１）Ｔｉ量およびＮｂ量が０．２０％を超える、又は、２）Ｖ量およびＷ量が１．０％を超えると、上記作用による効果は飽和し、コスト的に不利となる。したがって、Ｔｉ量およびＮｂ量は０．２０％以下とすることがよく、Ｖ量およびＷ量は１．０％以下とすることがよい。Ｔｉ量およびＮｂ量は０．１５％以下が好ましく、Ｖ量およびＷ量は０．５％以下が好ましい。上記作用による効果をより確実に得るためには、Ｔｉ量およびＮｂ量の下限値を０．０１％以上、Ｖ量およびＷ量の下限値を０．１％以上とすることが好ましい。 (Ti: 0% to 0.20%, Nb: 0% to 0.20%, V: 0% to 1.0%, W: 0% to 1.0%)
Ti, Nb, V, and W are elements that promote mutual diffusion of Fe and Al in the aluminum-plated layer and the base steel sheet. Therefore, at least one of Ti, Nb, V, and W may be contained in the base steel sheet. However, if 1) the amount of Ti and Nb exceeds 0.20%, or 2) the amount of V and W exceeds 1.0%, the effect of the above action is saturated, which is disadvantageous in terms of cost. Therefore, the Ti amount and the Nb amount are often 0.20% or less, and the V amount and the W amount are preferably 1.0% or less. The Ti amount and Nb amount are preferably 0.15% or less, and the V amount and W amount are preferably 0.5% or less. In order to obtain the effect of the above action more reliably, it is preferable that the lower limit of the Ti amount and the Nb amount is 0.01% or more, and the lower limit values of the V amount and the W amount are 0.1% or more.
（Ｃｒ：０％～１．０％、Ｍｏ：０％～１．０％、Ｃｕ：０％～１．０％、Ｎｉ：０％～１．０％、Ｂ：０％～０．０１００％）
　Ｃｒ、Ｍｏ、Ｃｕ、Ｎｉ、およびＢは、母材鋼板の焼入れ性を高め、かつ焼入れ後強度を安定して確保するために、効果のある元素である。したがって、これらの元素のうちの１種または２種以上を含有させてもよい。しかし、Ｃｒ、Ｍｏ、Ｃｕ、およびＮｉの含有量については１．０％超、Ｂ量については０．０１００％超としても、上記効果は飽和して、コスト的に不利となる。したがって、Ｃｒ、Ｍｏ、Ｃｕ、およびＮｉの含有量は１．０％以下とすることがよい。また、Ｂ量は０．０１００％以下とすることがよく、０．００８０％以下とすることが好ましい。上記効果をより確実に得るためには、Ｃｒ、Ｍｏ、Ｃｕ、およびＮｉの含有量が０．１％以上、並びにＢの含有量が０．００１０％以上のいずれかを満足させることが好ましい。 (Cr: 0% to 1.0%, Mo: 0% to 1.0%, Cu: 0% to 1.0%, Ni: 0% to 1.0%, B: 0% to 0.0100% )
Cr, Mo, Cu, Ni, and B are elements that are effective in enhancing the hardenability of the base steel sheet and stably ensuring the strength after quenching. Therefore, one or more of these elements may be contained. However, even if the contents of Cr, Mo, Cu, and Ni are more than 1.0% and the amount of B is more than 0.0100%, the above effect is saturated and it is disadvantageous in terms of cost. Therefore, the content of Cr, Mo, Cu, and Ni is preferably 1.0% or less. The amount of B is preferably 0.0100% or less, preferably 0.0080% or less. In order to obtain the above effect more reliably, it is preferable that the content of Cr, Mo, Cu, and Ni is 0.1% or more, and the content of B is 0.0010% or more.
（Ｃａ：０％～０．０５％、Ｍｇ：０％～０．０５％、ＲＥＭ：０％～０．０５％）
　Ｃａ、Ｍｇ、およびＲＥＭは、鋼中の介在物の形態を微細化し、介在物による熱間プレス成形時の割れの発生を防止する作用を有する。したがって、これらの元素の１種または２種以上を含有させてもよい。しかし、過剰に添加すると、鋼中の介在物の形態を微細化する効果は飽和し、コスト増を招くだけとなる。したがって、Ｃａ量は０．０５％以下、Ｍｇ量は０．０５％以下、ＲＥＭ量は０．０５％以下とすることがよい。上記作用による効果をより確実に得るためには、Ｃａ量を０．０００５％以上、Ｍｇ量を０．０００５％以上、およびＲＥＭ量を０．０００５％以上のいずれかを満足させることが好ましい。 (Ca: 0% to 0.05%, Mg: 0% to 0.05%, REM: 0% to 0.05%)
Ca, Mg, and REM have the effect of refining the morphology of inclusions in steel and preventing the occurrence of cracks during hot press forming due to inclusions. Therefore, one or more of these elements may be contained. However, when added in excess, the effect of miniaturizing the morphology of inclusions in steel is saturated, which only increases the cost. Therefore, the Ca amount is preferably 0.05% or less, the Mg amount is 0.05% or less, and the REM amount is 0.05% or less. In order to obtain the effect of the above action more reliably, it is preferable to satisfy any one of Ca amount of 0.0005% or more, Mg amount of 0.0005% or more, and REM amount of 0.0005% or more.
　ここで、ＲＥＭは、Ｓｃ、Ｙおよびランタノイドの合計１７元素を指し、上記ＲＥＭの含有量は、これらの元素の合計含有量を指す。ランタノイドの場合、工業的にはミッシュメタルの形で添加される。 Here, REM refers to a total of 17 elements of Sc, Y and lanthanoid, and the content of REM refers to the total content of these elements. In the case of lanthanoids, they are industrially added in the form of misch metal.
（Ｂｉ：０％～０．０５％）
　Ｂｉは、溶鋼の凝固過程において凝固核となり、デンドライトの２次アーム間隔を小さくすることにより、デンドライト２次アーム間隔内への偏析（例えば、Ｍｎ）を抑制する作用を有する元素である。したがって、Ｂｉを含有させてもよい。特に熱間プレス用鋼板のように多量のＭｎを含有させることがよく行われる鋼板については、Ｂｉは、Ｍｎの偏析に起因する靭性の劣化を抑制する効果がある。したがって、そのような鋼種には、Ｂｉを含有させることが好ましい。しかし、０．０５％を超えてＢｉを含有させても、上記作用による効果は飽和してしまい、コストの増加を招く。したがって、Ｂｉ量は０．０５％以下とする。好ましくは０．０２％以下である。なお、上記作用による効果をより確実に得るためには、Ｂｉ量を０．０００２％以上とすることが好ましい。さらに好ましくは０．０００５％以上である。 (Bi: 0% to 0.05%)
Bi is an element that becomes a solidified nucleus in the solidification process of molten steel and has an effect of suppressing segregation (for example, Mn) into the dendrite secondary arm spacing by reducing the dendrite secondary arm spacing. Therefore, Bi may be contained. In particular, for a steel sheet that often contains a large amount of Mn, such as a steel sheet for hot pressing, Bi has an effect of suppressing deterioration of toughness due to segregation of Mn. Therefore, it is preferable that such a steel grade contains Bi. However, even if Bi is contained in an amount of more than 0.05%, the effect of the above action is saturated, resulting in an increase in cost. Therefore, the amount of Bi is set to 0.05% or less. It is preferably 0.02% or less. In addition, in order to obtain the effect of the above action more reliably, the Bi amount is preferably 0.0002% or more. More preferably, it is 0.0005% or more.
（Ｓｉ：０％～２．００％）
　Ｓｉは、固溶強化元素であり、２．００％までは有効に活用できる。しかし、Ｓｉは２．００％を超えて含有させると、めっき性に不具合が生じることが懸念される。したがって、Ｓｉを含有する場合、Ｓｉ量は２．００％以下とすることがよい。好ましい上限は１．４０％以下、さらに好ましくは１．００％以下である。下限は特に限定されず、上記作用による効果をより確実に得るためには、０．０１％以上が好ましい。 (Si: 0% to 2.00%)
Si is a solid solution strengthening element and can be effectively utilized up to 2.00%. However, if Si is contained in an amount of more than 2.00%, there is a concern that the plating property may be defective. Therefore, when Si is contained, the amount of Si is preferably 2.00% or less. The preferred upper limit is 1.40% or less, more preferably 1.00% or less. The lower limit is not particularly limited, and 0.01% or more is preferable in order to obtain the effect of the above action more reliably.
（Ｐ：０％～０．０３％）
　Ｐは、不純物として含有される元素である。Ｐは過剰に含有すると、母材鋼板の靱性が低下しやすくなる。したがって、Ｐ量は０．０３％以下とすることがよい。好ましくは０．０１％以下である。Ｐ量の下限は特に規定する必要はない。Ｐ量は０％でもよく、０％超でもよい。コストの観点からは０．０００２％以上とすることが好ましい。 (P: 0% to 0.03%)
P is an element contained as an impurity. If P is contained in excess, the toughness of the base steel sheet tends to decrease. Therefore, the amount of P is preferably 0.03% or less. It is preferably 0.01% or less. The lower limit of the amount of P does not need to be specified. The amount of P may be 0% or more than 0%. From the viewpoint of cost, it is preferably 0.0002% or more.
（Ｓ：０％～０．０１０％）
　Ｓは、不純物として含有される元素であり、ＭｎＳを形成し、母材鋼板を脆化させる作用を有する。したがって、Ｓ量は０．０１０％以下とすることがよい。より望ましいＳ量は０．００４％以下である。Ｓ量の下限は特に規定する必要はない。Ｓ量は０％でもよく、０％超でもよい。コストの観点からは０．０００２％以上とすることが好ましい。 (S: 0% to 0.010%)
S is an element contained as an impurity and has an action of forming MnS and embrittlement of the base steel sheet. Therefore, the amount of S is preferably 0.010% or less. A more desirable amount of S is 0.004% or less. The lower limit of the amount of S does not need to be specified. The amount of S may be 0% or more than 0%. From the viewpoint of cost, it is preferably 0.0002% or more.
（Ｎ：０％～０．０１０％）
　Ｎは、不純物として含有され、鋼中にて介在物を形成し、熱間プレス成形後の靱性を劣化させる元素である。したがって、Ｎ量は０．０１０％以下とすることがよい。好ましくは０．００８％以下、さらに好ましくは０．００５％以下である。Ｎ量の下限は特に規定する必要はない。Ｎ量は０％でもよく、０％超でもよい。コストの観点からは０．０００２％以上とすることが好ましい。 (N: 0% to 0.010%)
N is an element contained as an impurity that forms inclusions in steel and deteriorates toughness after hot press forming. Therefore, the amount of N is preferably 0.010% or less. It is preferably 0.008% or less, more preferably 0.005% or less. The lower limit of the amount of N does not need to be specified. The amount of N may be 0% or more than 0%. From the viewpoint of cost, it is preferably 0.0002% or more.
（残部）
　残部は、Ｆｅおよび不純物である。ここで、不純物とは、鉱石、スクラップ等の原材料に含まれる成分、または、製造の過程で混入する成分が例示され、意図的に母材鋼板に含有させたものではない成分を指す。 (Remaining)
The rest are Fe and impurities. Here, the impurity refers to a component contained in raw materials such as ore and scrap, or a component mixed in the manufacturing process, which is not intentionally contained in the base steel sheet.
［アルミニウムめっき層］
　アルミニウムめっき層は、母材鋼板の両面に形成される。アルミニウムめっき層を形成する方法は、特に限定されるものではない。例えば、アルミニウムめっき層は、溶融めっき法によって母材鋼板の両面に形成してもよい。溶融めっき法は、アルミニウムを主体として含む溶融金属浴中に母材鋼板を浸漬させ、母材鋼板の両面にアルミニウムめっきを施す方法である。 [Aluminum plating layer]
The aluminum plating layer is formed on both sides of the base steel plate. The method for forming the aluminum plating layer is not particularly limited. For example, the aluminum plating layer may be formed on both sides of the base steel sheet by a hot dip galvanizing method. The hot-dip galvanizing method is a method in which a base steel sheet is immersed in a molten metal bath containing mainly aluminum, and aluminum plating is applied to both surfaces of the base steel sheet.
　ここで、アルミニウムめっき層とは、アルミニウムを主体として含むめっき層であり、アルミニウムを５０質量％以上含有していればよい。目的に応じて、アルミニウム以外の元素（例えば、Ｓｉなど）を含んでいてもよく、製造の過程などで混入してしまう不純物を含んでいてもよい。アルミニウムめっき層は、具体的には、例えば、質量％で、Ｓｉ（シリコン）を５％～１２％含み、残部はアルミニウムおよび不純物からなる化学組成を有していてもよい。また、質量％で、Ｓｉ（シリコン）を５％～１２％、Ｆｅ（鉄）を２％～４％を含み、残部はアルミニウムおよび不純物からなる化学組成を有していてもよい。
　上記範囲でＳｉを含有させると、加工性及び耐食性の低下が抑制され得る。また、金属間化合物層の厚みを低減し得る。 Here, the aluminum plating layer is a plating layer containing aluminum as a main component, and may contain 50% by mass or more of aluminum. Depending on the purpose, it may contain an element other than aluminum (for example, Si), or may contain impurities that are mixed in during the manufacturing process. Specifically, the aluminum-plated layer may contain, for example, 5% to 12% of Si (silicon) in mass%, and the balance may have a chemical composition consisting of aluminum and impurities. Further, it may contain 5% to 12% of Si (silicon) and 2% to 4% of Fe (iron) in mass%, and the balance may have a chemical composition consisting of aluminum and impurities.
When Si is contained in the above range, deterioration of workability and corrosion resistance can be suppressed. Moreover, the thickness of the intermetallic compound layer can be reduced.
　突合せ溶接用鋼板の縁部以外の領域に設けられたアルミニウムめっき層の厚みは、特に限定されず、例えば、厚みで８μｍ～５０μｍの範囲であることがよく、８μｍ～３５μｍの範囲であることが好ましく、１５μｍ～３０μｍの範囲であることがより好ましい。なお、アルミニウムめっき層の厚みは、突合せ溶接用鋼板の縁部以外の領域における厚みの平均値を表す。 The thickness of the aluminum-plated layer provided in the region other than the edge of the butt-welding steel sheet is not particularly limited, and for example, the thickness is often in the range of 8 μm to 50 μm, and may be in the range of 8 μm to 35 μm. It is preferably in the range of 15 μm to 30 μm, more preferably. The thickness of the aluminum-plated layer represents the average value of the thickness in the region other than the edge of the butt-welding steel plate.
　アルミニウムめっき層は、突合せ溶接用鋼板の腐食を防止する。また、アルミニウムめっき層は、テーラードブランクを熱間プレス成形により加工する場合に、高温に加熱されても、表面が酸化することによるスケール（鉄の化合物）の発生を抑制する。また、アルミニウムめっき層は、有機系材料によるめっき被覆、又は他の金属系材料（例えば、亜鉛系材料）によるめっき被覆よりも沸点及び融点が高い。従って、熱間プレス成形により成形する際に、被覆が蒸発することがないため、表面の保護効果が高い。 The aluminum plating layer prevents corrosion of the steel plate for butt welding. Further, when the tailored blank is processed by hot press molding, the aluminum-plated layer suppresses the generation of scale (iron compound) due to surface oxidation even when heated to a high temperature. Further, the aluminum plating layer has a higher boiling point and melting point than the plating coating with an organic material or the plating coating with another metal material (for example, a zinc material). Therefore, when molding by hot press molding, the coating does not evaporate, so that the surface protection effect is high.
　溶融めっき時及び熱間プレス成形時における加熱により、アルミニウムめっき層は、母材鋼板中の鉄（Ｆｅ）と合金化し得る。よって、アルミニウムめっき層は、必ずしも成分組成が一定な単一の層で形成されるとは限らず、部分的に合金化した層（合金層）を含むものとなる。 The aluminum plating layer can be alloyed with iron (Fe) in the base steel sheet by heating during hot dip galvanizing and hot press forming. Therefore, the aluminum-plated layer is not always formed of a single layer having a constant component composition, but includes a partially alloyed layer (alloy layer).
［金属間化合物層］
　金属間化合物層は、母材鋼板上にアルミニウムめっきを設ける際に、母材鋼板とアルミニウムめっき層との間の境界部に形成される層である。具体的には、金属間化合物層は、アルミニウムを主体として含む溶融金属浴中での母材鋼板の鉄（Ｆｅ）とアルミニウム（Ａｌ）を含む金属との反応によって形成される。金属間化合物層は、主にＦｅｘＡｌｙ（ｘ、ｙは１以上を表す）で表される化合物の複数種で形成されている。アルミニウムめっき層がＳｉ（シリコン）を含む場合は、ＦｅｘＡｌｙおよびＦｅｘＡｌｙＳｉｚ（ｘ、ｙ、ｚは１以上を表す）で表される化合物の複数種で形成されている。
　ここで、本開示において、縁部の少なくとも一部に形成される金属間化合物層（ＩＭＣ１）と、金属間化合物層（ＩＭＣ０）とに共通する内容については、単に金属間化合物層と称する。 [Intermetallic compound layer]
The intermetallic compound layer is a layer formed at the boundary between the base steel plate and the aluminum plating layer when aluminum plating is provided on the base steel plate. Specifically, the intermetallic compound layer is formed by the reaction of iron (Fe) of the base steel sheet with a metal containing aluminum (Al) in a molten metal bath containing aluminum as a main component. The intermetallic compound layer is mainly formed of a plurality of types of compounds represented by Fe x Al y (x and y represent 1 or more). When the aluminum plating layer contains Si (silicon), it is formed of a plurality of kinds of compounds represented by Fe x Al y and Fe x Al y Si z (x, y, z represent 1 or more).
Here, in the present disclosure, the content common to the intermetallic compound layer (IMC 1 ) formed in at least a part of the edge portion and the intermetallic compound layer (IMC 0 ) is simply referred to as an intermetallic compound layer. ..
　突合せ溶接用鋼板の縁部以外の領域に形成される金属間化合物層（ＩＭＣ０）の厚みは、３μｍ～１０μｍの範囲である（つまり、前述の式（２）を満足する。）。金属間化合物層（ＩＭＣ０）の厚みは、４μｍ～８μｍの範囲であることが好ましい。
　金属間化合物層（ＩＭＣ０）の厚みが、１０μｍ以下であると、アルミニウムめっき層および金属間化合物層のクラックの発生が抑制されるとともに、アルミニウムめっき層の欠落の発生も抑制される。これにより、縁部以外の領域における母材鋼板の耐食性の低下が抑制される。また、溶接予定部の縁部をレーザガウジング処理した場合、金属間化合物層（ＩＭＣ１）の厚みを効率的に向上させる。
　一方、金属間化合物層（ＩＭＣ０）の厚みが、３μｍ以上であると、アルミニウムめっき層の移動が生じ難くなる。それにより、突合せ溶接において、溶接金属へのアルミニウムめっき層に起因するアルミニウムの多量の混入が抑制されるため、溶接金属の強度の低下が抑制される。また、ホットスタンプにおいて、アルミニウムめっき層の垂れが抑制されることで、アルミニウムめっき層の厚みの均一性が確保される。 The thickness of the intermetallic compound layer (IMC 0 ) formed in the region other than the edge of the butt welding steel sheet is in the range of 3 μm to 10 μm (that is, the above formula (2) is satisfied). The thickness of the intermetallic compound layer (IMC 0 ) is preferably in the range of 4 μm to 8 μm.
When the thickness of the intermetallic compound layer (IMC 0 ) is 10 μm or less, the occurrence of cracks in the aluminum plating layer and the intermetallic compound layer is suppressed, and the occurrence of chipping of the aluminum plating layer is also suppressed. As a result, the deterioration of the corrosion resistance of the base steel sheet in the region other than the edge portion is suppressed. Further, when the edge portion of the planned welding portion is subjected to laser gouging treatment, the thickness of the intermetallic compound layer (IMC 1 ) is efficiently improved.
On the other hand, when the thickness of the intermetallic compound layer (IMC 0 ) is 3 μm or more, the movement of the aluminum plating layer is less likely to occur. As a result, in butt welding, a large amount of aluminum mixed into the weld metal due to the aluminum plating layer is suppressed, so that a decrease in the strength of the weld metal is suppressed. Further, in hot stamping, the uniformity of the thickness of the aluminum plating layer is ensured by suppressing the sagging of the aluminum plating layer.
［突合せ溶接用鋼板の縁部］
　本開示の突合せ溶接用鋼板は、縁部の少なくとも一部において、母材鋼板の両面上に少なくとも金属間化合物層（ＩＭＣ１）が形成されている。縁部に形成された金属間化合物層（ＩＭＣ１）上には、アルミニウムめっき層が除去されていてもよく、厚みが低減されているアルミニウムめっき層が残存していてもよい。
　また、金属間化合物層（ＩＭＣ１）の厚みは、縁部以外の領域における金属間化合物層（ＩＭＣ０）の厚みよりも大きい。金属間化合物層（ＩＭＣ１）は、溶接予定部の縁部に形成される。 [Rim of steel plate for butt welding]
In the butt welding steel sheet of the present disclosure, at least an intermetallic compound layer (IMC 1 ) is formed on both sides of the base steel sheet at least a part of the edge portion. The aluminum plating layer may be removed or the aluminum plating layer having a reduced thickness may remain on the intermetallic compound layer (IMC 1 ) formed at the edge portion.
The thickness of the intermetallic compound layer (IMC 1) is greater than the thickness of the intermetallic compound layer in the region other than the edge (IMC 0). The intermetallic compound layer (IMC 1 ) is formed at the edge of the planned weld.
　縁部の少なくとも一部に設けられる金属間化合物層（ＩＭＣ１）は、突合せ溶接用鋼板が備える縁部のうち、溶接予定部の縁部に設けられていれば、特に限定されない。例えば
、金属間化合物層（ＩＭＣ１）は、溶接予定部の縁部において、下記に挙げる態様で設けられていてもよい。
　１）対向する端面から端面までの長さに対して、突合せ溶接用鋼板の端面から５％以内の範囲の全領域であって、突合せ溶接用鋼板の端縁に沿って設けられる態様。
　２）対向する端面から端面までの長さに対して、突合せ溶接用鋼板の端面から５％以内の範囲内の一部分の領域であって、突合せ溶接用鋼板の端縁に沿って設けられている態様。
　３）上記１）または２）の態様において、突合せ溶接用鋼板の端縁の全長に沿って設けられる態様。
　４）上記１）または２）の態様において、突合せ溶接用鋼板の端縁の全長のうち、突合せ溶接を行う部分に対応する長さのみに沿って設けられる態様。
　５）対向する端面から端面までの長さに対して、突合せ溶接用鋼板の端面から５％以内の範囲のうち、突合せ溶接用鋼板の端縁を除く領域に設けられる態様。 The intermetallic compound layer (IMC 1 ) provided at least a part of the edge portion is not particularly limited as long as it is provided at the edge portion of the planned welding portion among the edge portions provided in the butt welding steel plate. For example, the intermetallic compound layer (IMC 1 ) may be provided at the edge of the planned welding portion in the following manners.
1) An embodiment in which the entire region is within 5% of the end face of the butt welding steel plate with respect to the length from the opposite end face to the end face, and is provided along the edge of the butt welding steel plate.
2) A part of the area within 5% of the end face of the butt welding steel plate with respect to the length from the opposite end face to the end face, and is provided along the edge of the butt welding steel plate. Aspect.
3) In the aspect of 1) or 2) above, the aspect provided along the entire length of the edge of the butt welding steel plate.
4) In the aspect of 1) or 2) above, the aspect is provided along only the length corresponding to the portion to be butt-welded in the total length of the edge of the butt-welding steel plate.
5) An embodiment provided in a region excluding the edge of the butt-welding steel sheet within a range of 5% or less from the end face of the butt-welding steel sheet with respect to the length from the opposite end face to the end face.
　溶接を予定していない縁部では、金属間化合物層（ＩＭＣ１）が形成されておらず、金属間化合物層（ＩＭＣ０）のままであってもよい。この場合、溶接を予定していない縁部では、縁部以外の領域と同様の構造となる。また、溶接を予定していない縁部にも、必要に応じて、金属間化合物層（ＩＭＣ１）が形成されていてもよい。溶接予定部の縁部は、テーラードブランクを形成するための突合せ溶接を行う縁部を表す。溶接を予定していない縁部は、テーラードブランクを形成するための突合せ溶接をする予定のない縁部を表す。 The intermetallic compound layer (IMC 1 ) is not formed at the edge portion that is not scheduled to be welded, and the intermetallic compound layer (IMC 0 ) may remain. In this case, the edge portion that is not scheduled to be welded has the same structure as the region other than the edge portion. Further, an intermetallic compound layer (IMC 1 ) may be formed on the edge portion that is not scheduled to be welded, if necessary. The edge of the planned weld represents the edge on which butt welding is performed to form a tailored blank. An edge that is not planned to be welded represents an edge that is not planned to be butt welded to form a tailored blank.
　本開示の突合せ溶接用鋼板は、金属間化合物層（ＩＭＣ１）の厚みが金属間化合物層（ＩＭＣ０）の厚みよりも大きい（つまり、前述の式（１）を満足する。）。そのため、前述の理由により、溶接部の塗装後耐食性に優れたものとなる。また、溶接金属の強度低下が抑制される。これらの観点で、金属間化合物層（ＩＭＣ１）の厚みは、５μｍ～３０μｍの範囲であることがよく、８μｍ～２５μｍの範囲であることが好ましく、８μｍ～１８μｍの範囲であることがより好ましい。金属間化合物層（ＩＭＣ１）の厚みが５μｍ以上であると、溶接部の塗装後耐食性がより優れたものとなる。一方、金属間化合物層（ＩＭＣ１）の厚みが３０μｍ以下であると、溶接金属の強度低下が抑制されやすくなる。
　なお、金属間化合物層（ＩＭＣ０）の厚みから金属間化合物層（ＩＭＣ１）の厚みが徐々に増加している部分は、金属間化合物層（ＩＭＣ１）の厚みの測定から除外される。つまり、金属間化合物層（ＩＭＣ１）の厚みは、金属間化合物層（ＩＭＣ０）の厚みからの増加が飽和している部分の厚みを表す。 Welding steel butt of the present disclosure is greater than the thickness of the intermetallic compound layer (IMC 1) Thickness intermetallic compound layer (IMC 0) (i.e., satisfies the equation (1) above.). Therefore, for the above-mentioned reason, the welded portion has excellent corrosion resistance after painting. In addition, the decrease in strength of the weld metal is suppressed. From these viewpoints, the thickness of the intermetallic compound layer (IMC 1 ) is preferably in the range of 5 μm to 30 μm, preferably in the range of 8 μm to 25 μm, and more preferably in the range of 8 μm to 18 μm. .. When the thickness of the intermetallic compound layer (IMC 1 ) is 5 μm or more, the corrosion resistance of the welded portion after painting becomes more excellent. On the other hand, when the thickness of the intermetallic compound layer (IMC 1 ) is 30 μm or less, the decrease in strength of the weld metal is likely to be suppressed.
The portion where the thickness of the intermetallic compound layer (IMC 1 ) gradually increases from the thickness of the intermetallic compound layer (IMC 0 ) is excluded from the measurement of the thickness of the intermetallic compound layer (IMC 1 ). In other words, the thickness of the intermetallic compound layer (IMC 1) represents the thickness of a portion increase from the thickness of the intermetallic compound layer (IMC 0) is saturated.
　金属間化合物層（ＩＭＣ１）の厚みは、金属間化合物層（ＩＭＣ０）の厚みに対する厚み比（ＩＭＣ１の厚み／ＩＭＣ０の厚み）として、厚み比が１を超える。この厚み比は、好ましくは１．２以上、より好ましくは１．５以上である。厚み比の上限は特に限定されず、例えば７以下が挙げられ、５以下が挙げられる。 The thickness of the intermetallic compound layer (IMC 1) is intermetallic compound layer as a (IMC 0) (the thicknesses of / IMC 0 of IMC 1) thickness ratio to the thickness of the thickness ratio exceeds 1. This thickness ratio is preferably 1.2 or more, more preferably 1.5 or more. The upper limit of the thickness ratio is not particularly limited, and examples thereof include 7 or less, and 5 or less.
　ここで、突合せ溶接用鋼板の縁部について、図１及び図２を参照して説明する。図１は、本開示の突合せ溶接用鋼板における溶接予定部の縁部周辺の一例を表す拡大概略断面図である。図２は、本開示の突合せ溶接用鋼板における溶接予定部の縁部周辺の他の一例を表す拡大概略断面図である。図１に示すように、突合せ溶接用鋼板１１０は、溶接予定部の縁部２２と縁部以外の領域２６とを有する。縁部以外の領域２６では、母材鋼板１２上に、金属間化合物層（ＩＭＣ０）１６Ａが設けられており、金属間化合物層（ＩＭＣ０）１６Ａ上に、アルミニウムめっき層１４Ａが設けられている。一方、溶接予定部の縁部２２では、母材鋼板１２上に、金属間化合物層（ＩＭＣ１）１６Ｂが設けられており、金属間化合物層（ＩＭＣ１）１６Ｂ上に、アルミニウムめっき層１４Ｂが設けられている。アルミニウムめっき層１４Ｂは、縁部以外の領域２６に設けられているアルミニウムめっき層１４Ａよりも厚みが減じられている。また、図２に示す突合せ溶接用鋼板１２０において、縁部以外の領域２６は、図１に示す突合せ溶接用鋼板１１０における縁部以外の領域２６と同様である。一方、溶接予定部の縁部２２では、母材鋼板１２上に、金属間化合物層（ＩＭＣ１）１６Ｂが設けられており、アルミニウムめっき層１４Ａが除去されている。 Here, the edge portion of the steel plate for butt welding will be described with reference to FIGS. 1 and 2. FIG. 1 is an enlarged schematic cross-sectional view showing an example of the periphery of the edge portion of the planned welding portion in the butt welding steel plate of the present disclosure. FIG. 2 is an enlarged schematic cross-sectional view showing another example around the edge portion of the planned welding portion in the butt welding steel plate of the present disclosure. As shown in FIG. 1, the butt-welding steel sheet 110 has an edge portion 22 of a planned welding portion and a region 26 other than the edge portion. In the region 26 other than the edge portion, the intermetallic compound layer (IMC 0 ) 16A is provided on the base steel plate 12, and the aluminum plating layer 14A is provided on the intermetallic compound layer (IMC 0 ) 16A. There is. On the other hand, at the edge portion 22 of the planned welding portion, the intermetallic compound layer (IMC 1 ) 16B is provided on the base steel plate 12, and the aluminum plating layer 14B is provided on the intermetallic compound layer (IMC 1 ) 16B. It is provided. The thickness of the aluminum-plated layer 14B is reduced as compared with the aluminum-plated layer 14A provided in the region 26 other than the edge portion. Further, in the butt welding steel plate 120 shown in FIG. 2, the region 26 other than the edge portion is the same as the region 26 other than the edge portion in the butt welding steel plate 110 shown in FIG. On the other hand, at the edge portion 22 of the planned welding portion, the intermetallic compound layer (IMC 1 ) 16B is provided on the base steel plate 12, and the aluminum plating layer 14A is removed.
　次に、図４及び図５を参照して、突合せ溶接用鋼板の縁部について説明する。図４は、未処理の縁部の一例を表す拡大断面写真である。図５は、本開示の突合せ溶接用鋼板における溶接予定部の縁部の一例を表す拡大断面写真である。図４に示す未処理の縁部は、母材鋼板１２上に、金属間化合物層（ＩＭＣ０）１６Ｃが設けられ、金属間化合物層（ＩＭＣ０）１６Ｃ上に、アルミニウムめっき層１４Ｃが設けられている。図４に示す縁部は、未処理であるので、金属間化合物層（ＩＭＣ０）１６Ｃの厚みは、縁部以外の領域における金属間化合物層の厚みと同程度である。これに対し、図５に示す縁部では、母材鋼板１２上に、金属間化合物層（ＩＭＣ１）１６Ｂが形成されている。したがって、本開示の突合せ溶接用鋼板における縁部では、図４に示す未処理の縁部と比較すると、図５に示すように、縁部における金属間化合物層（ＩＭＣ１）１６Ｂの厚みが厚いことがわかる。すなわち、図４及び図５に示す拡大断面写真から、本開示の突合せ溶接用鋼板は、溶接予定部の縁部における金属間化合物層（ＩＭＣ１）の厚みは、縁部以外の領域における金属間化合物層（ＩＭＣ０）の厚みよりも増加していることがわかる。 Next, the edge portion of the butt welding steel plate will be described with reference to FIGS. 4 and 5. FIG. 4 is an enlarged cross-sectional photograph showing an example of an untreated edge portion. FIG. 5 is an enlarged cross-sectional photograph showing an example of an edge portion of a planned welding portion in the butt welding steel plate of the present disclosure. In the untreated edge shown in FIG. 4, an intermetallic compound layer (IMC 0 ) 16C is provided on the base steel plate 12, and an aluminum plating layer 14C is provided on the intermetallic compound layer (IMC 0 ) 16C. ing. Since the edge portion shown in FIG. 4 is untreated, the thickness of the intermetallic compound layer (IMC 0 ) 16C is about the same as the thickness of the intermetallic compound layer in the region other than the edge portion. On the other hand, at the edge shown in FIG. 5, an intermetallic compound layer (IMC 1 ) 16B is formed on the base steel plate 12. Therefore, as shown in FIG. 5, the thickness of the intermetallic compound layer (IMC 1 ) 16B at the edge portion of the butt-welded steel sheet of the present disclosure is thicker than that of the untreated edge portion shown in FIG. You can see that. That is, from the enlarged cross-sectional photographs shown in FIGS. 4 and 5, in the steel plate for butt welding of the present disclosure, the thickness of the intermetallic compound layer (IMC 1 ) at the edge of the planned welding portion is the thickness between the metals in the region other than the edge. It can be seen that the thickness is larger than the thickness of the compound layer (IMC 0 ).
　本開示の突合せ溶接用鋼板は、縁部の少なくとも一部において、母材鋼板の両面上に、前述の金属間化合物層（ＩＭＣ０）の厚みよりも厚みの大きい金属間化合物層（ＩＭＣ１）が形成されている。金属間化合物層（ＩＭＣ１）が形成されている縁部では、金属間化合物層（ＩＭＣ１）のみ有していてもよい。また、溶接金属の機械的強度が低下しない範囲で、金属間化合物層（ＩＭＣ１）上に厚みが減少したアルミニウムめっき層を有していてもよい。特に、下記式（３）を満たす範囲であれば、金属間化合物層（ＩＭＣ１）に加えて、アルミニウムめっき層の存在は許容される。 The butt welding steel sheet of the present disclosure has an intermetallic compound layer (IMC 1 ) having a thickness larger than the thickness of the above-mentioned intermetallic compound layer (IMC 0 ) on both sides of the base steel sheet at least a part of the edge portion. Is formed. At the edge where the intermetallic compound layer (IMC 1 ) is formed, only the intermetallic compound layer (IMC 1 ) may be provided. Further, an aluminum plating layer having a reduced thickness may be provided on the intermetallic compound layer (IMC 1 ) as long as the mechanical strength of the weld metal does not decrease. In particular, the presence of an aluminum-plated layer in addition to the intermetallic compound layer (IMC 1 ) is permitted as long as the following formula (3) is satisfied.
　本開示の突合せ溶接用鋼板は、金属間化合物層（ＩＭＣ１）が形成された縁部でのアルミニウムめっき層の片面あたりの厚みをａ１（μｍ）、金属間化合物層（ＩＭＣ１）の片面あたりの厚みをｂ１（μｍ）、母材鋼板の板厚をｔ０（μｍ）としたとき、下記式（３）の関係を満足する。なお、板厚は、縁部以外の領域で測定した母材鋼板の厚みを表す。式（３）の板厚は、μｍに換算して代入する。
　式（３）：０．８％≦｛２×（ａ１（μｍ）＋ｂ１（μｍ））／ｔ０（μｍ）｝×１００≦３．５％ The steel sheet for butt welding of the present disclosure has a thickness of a 1 (μm) per side of the aluminum plating layer at the edge where the intermetallic compound layer (IMC 1 ) is formed, and one side of the intermetallic compound layer (IMC 1 ). When the thickness per area is b 1 (μm) and the thickness of the base steel plate is t 0 (μm), the relationship of the following formula (3) is satisfied. The plate thickness represents the thickness of the base steel plate measured in a region other than the edge portion. The plate thickness of the formula (3) is converted into μm and substituted.
Equation (3): 0.8% ≤ {2 × (a 1 (μm) + b 1 (μm)) / t 0 (μm)} × 100 ≦ 3.5%
　ここで、再び図１及び図２を参照して、ａ１及びｂ１について説明する。図１に示すように、金属間化合物層（ＩＭＣ１）１６Ｂ上に、アルミニウムめっき層１４Ｂを有している場合、ａ１は、アルミニウムめっき層１４Ｂの厚み（μｍ）を示す。ｂ１は、金属間化合物層（ＩＭＣ１）１６Ｂの厚み（μｍ）を示す。また、図２に示すように、金属間化合物層（ＩＭＣ１）１６Ｂ上のアルミニウムめっき層が除去されている場合（つまり、アルミニウムめっき層１４Ｂを有さない場合）は、ａ１は、０（μｍ）を示し、ｂ１は、金属間化合物層（ＩＭＣ１）１６Ｂの厚み（μｍ）を示す。 Here, a 1 and b 1 will be described with reference to FIGS. 1 and 2 again. As shown in FIG. 1, the intermetallic compound layer on (IMC 1) 16B, if it has an aluminum-plated layer 14B, a 1 indicates the thickness of the aluminum layer 14B (μm). b 1 indicates the thickness (μm) of the intermetallic compound layer (IMC 1 ) 16B. Further, as shown in FIG. 2, when the aluminum plating layer on the intermetallic compound layer (IMC 1 ) 16B is removed (that is, when the aluminum plating layer 14B is not provided), a 1 is 0 (that is, when the aluminum plating layer 14B is not provided). μm), where b 1 indicates the thickness (μm) of the intermetallic compound layer (IMC 1 ) 16B.
　なお、ｂ１は、前述の金属間化合物層（ＩＭＣ１）の厚みと同義である。ａ１は、縁部以外の領域におけるアルミニウムめっき層の厚みが徐々に減少している部分を除いた部分の厚みを表す。つまり、ａ１は、アルミニウムめっき層の厚みの減少が飽和した部分の厚みを表す。アルミニウムめっき層が存在しなくなるまで減少した場合、ａ１は０（ゼロ）（μｍ）となる。ただし、アルミニウムめっき層が存在しなくなるまで減少し、再びアルミニウムめっき層が存在する場合（例えば、アルミニウムめっき層が縁部以外の領域から離れて存在する場合など、）は、再び存在しているアルミニウムめっき層の厚みをａ１とする。 Note that b 1 is synonymous with the thickness of the above-mentioned intermetallic compound layer (IMC 1 ). a 1 represents the thickness of the portion excluding the portion where the thickness of the aluminum layer in the region other than the edge gradually decreases. That, a 1 represents the thickness of the portion decrease in thickness of the aluminum layer is saturated. When the aluminum plating layer is reduced until it disappears, a 1 becomes 0 (zero) (μm). However, it decreases until the aluminum plating layer disappears, and if the aluminum plating layer exists again (for example, when the aluminum plating layer exists away from the region other than the edge), the aluminum that exists again the thickness of the plating layer and a 1.
　上記式（３）で表される値が３．５％を超えると、溶接金属（溶接後の溶融凝固領域）中の平均アルミニウム濃度が増加するため、焼入れされない軟質な部位が発生して、ホットスタンプ成形品の機械的強度が低下しやすい。一方、上記式（３）で表される値が０．８％を下回ると、溶接部における塗装後の耐食性が低下しやすい。上記式（３）で表される値は１．０％～３．５％の範囲が好ましく、１．６％～３．３％の範囲がより好ましく、２．０％～３．０％の範囲がさらに好ましい。
　なお、「片面あたり」とは、片面での厚みの測定値を表す。具体的には、縁部に形成された金属間化合物層（ＩＭＣ１）、および金属間化合物層（ＩＭＣ１）上に存在するアルミニウムめっき層が片面で、式（３）を満足していればよい。両面とも式（３）を満足していることが好ましい。また、金属間化合物層（ＩＭＣ１）上に、アルミニウムめっき層が存在しない場合は、式（３）のａ１に０（ゼロ）を代入する。 When the value represented by the above formula (3) exceeds 3.5%, the average aluminum concentration in the weld metal (molten solidification region after welding) increases, so that soft parts that are not hardened are generated and become hot. The mechanical strength of stamped products tends to decrease. On the other hand, when the value represented by the above formula (3) is less than 0.8%, the corrosion resistance of the welded portion after painting tends to decrease. The value represented by the above formula (3) is preferably in the range of 1.0% to 3.5%, more preferably in the range of 1.6% to 3.3%, and preferably in the range of 2.0% to 3.0%. The range is even more preferred.
In addition, "per one side" represents the measured value of the thickness on one side. Specifically, if the intermetallic compound layer (IMC 1 ) formed at the edge and the aluminum plating layer existing on the intermetallic compound layer (IMC 1 ) are on one side and satisfy the formula (3). Good. It is preferable that both sides satisfy the formula (3). Further, on the intermetallic compound layer (IMC 1), if the aluminum plating layer does not exist, it is substituted into a 1 of the formula (3) 0 (zero).
　なお、アルミニウムめっき層の片面あたりの厚みａ１（μｍ）、及び金属間化合物層（ＩＭＣ１）の片面あたりの厚みｂ１（μｍ）の測定は、後述のアルミニウムめっき層および金属間化合物層（ＩＭＣ１）と同様の手順にて行えばよい。 The thickness a 1 (μm) per side of the aluminum plating layer and the thickness b 1 (μm) per side of the intermetallic compound layer (IMC 1 ) can be measured by measuring the aluminum plating layer and the intermetallic compound layer (IMC 1 ) described later. The procedure may be the same as for IMC 1 ).
　前述のように、突合せ溶接用鋼板の縁部の少なくとも一部に形成される金属間化合物層（ＩＭＣ１）は、突合せ溶接用鋼板の溶接予定部の縁部に形成される。溶接予定部の縁部に形成される金属間化合物層（ＩＭＣ１）の幅は、平均で０．２ｍｍ～５．０ｍｍであることがよい。レーザ溶接に用いる場合、好ましくは０．６ｍｍ～１．５ｍｍである。プラズマ溶接に用いる場合、好ましくは、１．０ｍｍ～４．０ｍｍである。 As described above, the intermetallic compound layer (IMC 1 ) formed on at least a part of the edge portion of the butt-welding steel sheet is formed on the edge portion of the planned welding portion of the butt-welding steel sheet. The width of the intermetallic compound layer (IMC 1 ) formed at the edge of the planned welding portion is preferably 0.2 mm to 5.0 mm on average. When used for laser welding, it is preferably 0.6 mm to 1.5 mm. When used for plasma welding, it is preferably 1.0 mm to 4.0 mm.
　なお、突合せ溶接用鋼板の縁部に形成された金属間化合物層（ＩＭＣ１）の幅は、金属間化合物層（ＩＭＣ１）の幅を５箇所の位置で測定した値の平均値である。具体的な測定方法は、以下のとおりである。
　まず、突合せ溶接用鋼板の縁部に形成された金属間化合物層（ＩＭＣ１）の全幅が観察可能な断面を含む測定用試料を５箇所採取する。すなわち、測定用試料は、突合せ溶接用鋼板の端縁に沿う方向に形成された金属間化合物層（ＩＭＣ１）の長さＬ（図１に示すＸ方向（溶接予定部が延びる方向）の金属間化合物層（ＩＭＣ１）の長さＬ）を５等分した５箇所のおける中央位置付近から採取する。ここで、図３を参照して説明すると、図３に示すように、Ｘ方向に形成された金属間化合物層（ＩＭＣ１）の長さＬを５等分する。そして、長さＬを５等分した５箇所のそれぞれの部分において、矢印Ｆ１の方向に沿って、中央位置Ｃ付近を通る位置から測定用試料を採取する。
　次に、突合せ溶接用鋼板の断面が露出するように切断を行い、樹脂に埋め込み、研磨を行い、断面を光学顕微鏡で拡大する。そして、突合せ溶接用鋼板の端縁から、金属間化合物層（ＩＭＣ０）の厚みからの増加が飽和している部分までの距離を算出する。採取した各測定用試料について、同様の測定を行い、５箇所で測定した平均値を金属間化合物層（ＩＭＣ１）の幅とする。ここで、図１を参照すると、図１に示すＷが、縁部に形成された金属間化合物層（ＩＭＣ１）の幅である。 The width of the intermetallic compound layer formed at the edge of the butt welding steel plates (IMC 1) is an average value of values obtained by measuring the width at the position of the five locations of the intermetallic compound layer (IMC 1). The specific measurement method is as follows.
First, five measurement samples including a cross section in which the entire width of the intermetallic compound layer (IMC 1 ) formed on the edge of the butt welding steel plate can be observed are collected. That is, the measurement sample is a metal having a length L of an intermetallic compound layer (IMC 1 ) formed in a direction along the edge of the butt-welding steel plate (in the X direction (direction in which the planned welding portion extends) shown in FIG. 1). The intermetallic layer (IMC 1 ) length L) is collected from the vicinity of the central position at 5 locations divided into 5 equal parts. Here, to explain with reference to FIG. 3, as shown in FIG. 3, the length L of the intermetallic compound layer (IMC 1 ) formed in the X direction is divided into five equal parts. Then, in each of the five parts obtained by dividing the length L into five equal parts, a measurement sample is collected from a position passing near the central position C along the direction of the arrow F1.
Next, the steel sheet for butt welding is cut so that the cross section is exposed, embedded in resin, polished, and the cross section is enlarged with an optical microscope. Then, the distance from the edge of the steel plate for butt welding to the portion where the increase from the thickness of the intermetallic compound layer (IMC 0 ) is saturated is calculated. The same measurement is performed for each sample for measurement collected, and the average value measured at five points is defined as the width of the intermetallic compound layer (IMC 1 ). Here, referring to FIG. 1, W shown in FIG. 1 is the width of the intermetallic compound layer (IMC 1 ) formed at the edge portion.
　突合せ溶接用鋼板の縁部に形成された金属間化合物層（ＩＭＣ１）上に、厚みが減じられているアルミニウムめっき層が存在する場合、このアルミニウムめっき層は、金属間化合物層（ＩＭＣ１）上の全域に残存していてもよい。ただし、アルミニウムめっき層は、静的引張強度の低下要因になるので、残存は少ない方が好ましい。この点で、金属間化合物層（ＩＭＣ１）上のアルミニウムめっき層は、突合せ溶接用鋼板の端縁から金属間化合物層（ＩＭＣ０）の厚みからの増加が飽和している部分までの距離に対して、５０％未満の割合で残存することがよい。アルミニウムめっき層が残存する割合は、好ましくは３０％以下、より好ましくは１０％以下である。 When an aluminum-plated layer having a reduced thickness is present on the intermetallic compound layer (IMC 1 ) formed at the edge of the butt-welding steel sheet, this aluminum-plated layer is the intermetallic compound layer (IMC 1 ). It may remain in the entire area above. However, since the aluminum-plated layer causes a decrease in static tensile strength, it is preferable that the residual amount is small. In this regard, the aluminum-plated layer on the intermetallic compound layer (IMC 1 ) is at the distance from the edge of the butt-welding steel sheet to the portion where the increase from the thickness of the intermetallic compound layer (IMC 0 ) is saturated. On the other hand, it is preferable that it remains at a rate of less than 50%. The ratio of the remaining aluminum plating layer is preferably 30% or less, more preferably 10% or less.
　ここで、母材鋼板、金属間化合物層、およびアルミニウムめっき層の確認、並びに、金属間化合物層、およびアルミニウムめっき層の厚みの測定については、以下のような方法によって行う。
　まず、端縁に直交する方向（つまり、図１に示すＹ方向）で、突合せ溶接用鋼板の断面が露出するように切断を行い、樹脂に埋め込む。埋め込んだ突合せ溶接用鋼板の断面を研磨する。研磨した突合せ溶接用鋼板の断面を、電子線マイクロアナライザ（ＦＥ－ＥＰＭＡ）により、突き合せ溶接用鋼板の表面から母材鋼板までを線分析し、アルミニウム濃度および鉄濃度を測定する。アルミニウム濃度および鉄濃度は、３回測定した平均値であることが好ましい。
　測定条件は、加速電圧１５ｋＶ、ビーム径１００ｎｍ程度、１点当たりの照射時間１０００ｍｓ、測定ピッチ６０ｎｍである。また、測定距離は、めっき層の厚みが測定できるようにすればよく、例えば、板厚方向に３０μｍ～８０μｍである。母材鋼板の板厚は、光学顕微鏡で測定することが好ましい。 Here, the confirmation of the base steel plate, the intermetallic compound layer, and the aluminum plating layer, and the measurement of the thickness of the intermetallic compound layer and the aluminum plating layer are performed by the following methods.
First, the steel sheet for butt welding is cut so as to be exposed in the direction orthogonal to the edge (that is, the Y direction shown in FIG. 1) and embedded in the resin. Polish the cross section of the embedded steel plate for butt welding. The cross section of the polished steel sheet for butt welding is line-analyzed from the surface of the steel sheet for butt welding to the base steel sheet by an electron probe microanalyzer (FE-EPMA), and the aluminum concentration and the iron concentration are measured. The aluminum concentration and the iron concentration are preferably average values measured three times.
The measurement conditions are an accelerating voltage of 15 kV, a beam diameter of about 100 nm, an irradiation time of 1000 ms per point, and a measurement pitch of 60 nm. The measurement distance may be such that the thickness of the plating layer can be measured, and is, for example, 30 μm to 80 μm in the plate thickness direction. The thickness of the base steel sheet is preferably measured with an optical microscope.
（母材鋼板、金属間化合物層、およびアルミニウムめっき層の範囲の規定）
　突合せ溶接用鋼板の断面のアルミニウム濃度の測定値として、アルミニウム（Ａｌ）濃度が２質量％未満である領域を母材鋼板と判断し、アルミニウム濃度が２質量％以上である領域を金属間化合物層またはアルミニウムめっき層と判断する。また、金属間化合物層およびアルミニウムめっき層のうち、鉄（Ｆｅ）濃度が４質量％超である領域を金属間化合物層、鉄濃度が４質量％以下である領域をアルミニウムめっき層と判断する。
　なお、金属間化合物層の厚みは、母材鋼板と金属間化合物層との境界から、金属間化合物層とアルミニウムめっき層との境界までの距離とする。また、アルミニウムめっき層の厚みは、金属間化合物層とアルミニウムめっき層との境界から、アルミニウムめっき層が形成された鋼板表面までの距離とする。 (Definition of the range of base steel sheet, intermetallic compound layer, and aluminum plating layer)
As a measurement value of the aluminum concentration in the cross section of the butt welding steel sheet, the region where the aluminum (Al) concentration is less than 2% by mass is determined to be the base steel sheet, and the region where the aluminum concentration is 2% by mass or more is the intermetallic compound layer. Or it is judged to be an aluminum plating layer. Further, among the intermetallic compound layer and the aluminum plating layer, a region having an iron (Fe) concentration of more than 4% by mass is determined to be an intermetallic compound layer, and a region having an iron concentration of 4% by mass or less is determined to be an aluminum plating layer.
The thickness of the intermetallic compound layer is the distance from the boundary between the base steel plate and the intermetallic compound layer to the boundary between the intermetallic compound layer and the aluminum plating layer. The thickness of the aluminum plating layer is the distance from the boundary between the intermetallic compound layer and the aluminum plating layer to the surface of the steel sheet on which the aluminum plating layer is formed.
　アルミニウムめっき層の厚み、及び金属間化合物層の厚みは、突合せ溶接用鋼板の表面から、母材鋼板の表面（母材鋼板および金属間化合物層の境界）までを線分析し、具体的には、次のようにして測定する。 The thickness of the aluminum plating layer and the thickness of the intermetallic compound layer are linearly analyzed from the surface of the butt welding steel sheet to the surface of the base steel sheet (the boundary between the base steel sheet and the intermetallic compound layer), and specifically. , Measure as follows.
－縁部以外の領域－
　縁部以外の領域におけるアルミニウムめっき層の厚み及び金属間化合物層（ＩＭＣ０）の厚みは、前述の判断基準にしたがって、突合せ溶接用鋼板の溶接予定部の端面から垂直方向に向かう方向（つまり、図１に示すＹ方向）に５等分した５箇所の中央位置付近で測定した平均値である。これらの厚みは、具体的には、以下のようにして求めた値である。
　アルミニウムめっき層の厚みは、上記のように５等分した５箇所の中央位置付近で、アルミニウムめっき層を有する鋼板表面から金属間化合物層までの厚みを求める。そして、求めた値の平均値をアルミニウムめっき層の厚みとする。ただし、アルミニウムめっき層の厚みの測定は、縁部以外の領域と縁部との境界付近における厚みが徐々に減少している部分の断面は除く。
　金属間化合物層（ＩＭＣ０）の厚みは、上記のように５等分した５箇所の中央位置付近で、金属間化合物層とアルミニウムめっき層との境界から金属間化合物層と母材鋼板との境界までの厚みを求める。そして、求めた値の平均値を金属間化合物層の厚みとする。ただし、金属間化合物層（ＩＭＣ０）の厚みの測定は、縁部以外の領域と縁部との境界付近における厚みが徐々に増加している部分の断面は除く。 -Area other than the edge-
The thickness of the aluminum plating layer and the thickness of the intermetallic compound layer (IMC 0 ) in the region other than the edge portion are in the direction perpendicular to the end face of the planned welding portion of the butt-welding steel sheet (that is, that is, according to the above-mentioned criteria. It is an average value measured near the center position of 5 points divided into 5 equal parts in the Y direction shown in FIG. Specifically, these thicknesses are values obtained as follows.
For the thickness of the aluminum plating layer, the thickness from the surface of the steel sheet having the aluminum plating layer to the intermetallic compound layer is determined in the vicinity of the center position of the five equal parts as described above. Then, the average value of the obtained values is taken as the thickness of the aluminum plating layer. However, the measurement of the thickness of the aluminum-plated layer excludes the cross section of the portion where the thickness is gradually decreasing near the boundary between the region other than the edge portion and the edge portion.
The thickness of the intermetallic compound layer (IMC 0 ) is such that the intermetallic compound layer and the base steel plate are formed from the boundary between the intermetallic compound layer and the aluminum plating layer near the center positions of the five equal parts as described above. Find the thickness to the boundary. Then, the average value of the obtained values is taken as the thickness of the intermetallic compound layer. However, the measurement of the thickness of the intermetallic compound layer (IMC 0 ) excludes the cross section of the portion where the thickness gradually increases near the boundary between the region other than the edge portion and the edge portion.
－縁部－
　アルミニウムめっき層が存在する場合、アルミニウムめっき層の厚みは、前述の判断基準にしたがって、アルミニウムめっき層が存在する鋼板表面から金属間化合物層までの厚みを測定する。ただし、厚みの測定は、厚みの減少が飽和した位置から突合せ溶接用鋼板の端縁までの全幅に対して、突合せ溶接用鋼板の端縁から１０％以内の範囲、及び厚みの減少が飽和した位置から突合せ溶接用鋼板の端縁側に向かって１０％以内の範囲を除いた領域を３等分し、３等分した中央位置で行う。そして、測定した３箇所の平均値とする。
　金属間化合物層（ＩＭＣ１）の厚みは、前述の判断基準にしたがって、アルミニウムめっき層を有する鋼板表面から金属間化合物層までの厚みを測定する。ただし、厚みの測定は、厚みの増加が飽和した位置から突合せ溶接用鋼板の端縁までの全幅に対して、突合せ溶接用鋼板の端縁から１０％以内の範囲、及び厚みの増加が飽和した位置から突合せ溶接用鋼板の端縁側に向かって１０％以内の範囲を除いた領域を３等分し、３等分した中央位置で行う。そして、測定した３箇所の平均値とする。
　ここで、図１を参照すると、溶接予定部の縁部２２において、アルミニウムめっき層１４Ｂの厚み（すなわちａ１）及び金属間化合物層（ＩＭＣ１）の厚み（すなわちｂ１）は、Ｙの範囲で測定した値の平均値であり、Ｘ１及びＸ２の範囲は測定から除いている。 -Rim-
When the aluminum plating layer is present, the thickness of the aluminum plating layer is measured from the surface of the steel sheet on which the aluminum plating layer is present to the intermetallic compound layer according to the above-mentioned criteria. However, the thickness was measured within 10% of the total width from the position where the thickness reduction was saturated to the edge of the butt welding steel sheet, and the thickness reduction was saturated. The region excluding the range within 10% from the position toward the edge side of the butt welding steel sheet is divided into three equal parts, and the measurement is performed at the central position divided into three equal parts. Then, the average value of the three measured points is used.
The thickness of the intermetallic compound layer (IMC 1 ) is measured from the surface of the steel sheet having the aluminum plating layer to the intermetallic compound layer according to the above-mentioned criteria. However, in the thickness measurement, the range from the position where the increase in thickness is saturated to the edge of the steel sheet for butt welding is within 10% of the edge of the steel sheet for butt welding, and the increase in thickness is saturated. The region excluding the range within 10% from the position toward the edge side of the butt welding steel sheet is divided into three equal parts, and the measurement is performed at the central position divided into three equal parts. Then, the average value of the three measured points is used.
Here, referring to FIG. 1, at the edge portion 22 of the planned welding portion, the thickness of the aluminum plating layer 14B (that is, a 1 ) and the thickness of the intermetallic compound layer (IMC 1 ) (that is, b 1 ) are in the range of Y. It is the average value of the values measured in, and the range of X 1 and X 2 is excluded from the measurement.
　突合せ溶接用鋼板の縁部の少なくとも一部に、金属間化合物層（ＩＭＣ１）を形成する好ましい方法の一例としては、例えば、次の方法が挙げられる。 As an example of a preferable method for forming an intermetallic compound layer (IMC 1 ) on at least a part of the edge portion of a steel sheet for butt welding, for example, the following method can be mentioned.
　突合せ溶接用鋼板の縁部の少なくとも一部に、母材鋼板の両面上に形成されたアルミニウムめっき層の表面に対し、レーザガウジング法による処理を施す工程を有する（形成法Ａとする）。 At least a part of the edge of the butt-welding steel sheet has a step of applying a treatment by a laser gouging method to the surface of the aluminum-plated layer formed on both sides of the base steel sheet (referred to as forming method A).
　形成法Ａは、以下のようにして、金属間化合物層（ＩＭＣ１）を形成する方法である。まず、テーラードブランクを形成する前の鋼板として、所望の大きさに切断した突合せ溶接用鋼板を準備する。次に、突合せ溶接用鋼板の縁部の一部に、突合せ溶接用鋼板の端縁に沿って、母材鋼板の両面上に形成されたアルミニウムめっき層の表面に対して、レーザガウジング法による処理を施す。それによって、金属間化合物層（ＩＭＣ１）を形成する方法である。 The forming method A is a method for forming an intermetallic compound layer (IMC 1 ) as follows. First, as a steel plate before forming a tailored blank, a steel plate for butt welding cut to a desired size is prepared. Next, the surface of the aluminum-plated layer formed on both sides of the base steel sheet along the edge of the butt-welding steel sheet on a part of the edge of the butt-welding steel sheet is treated by a laser gouging method. To give. Thereby, it is a method of forming an intermetallic compound layer (IMC 1 ).
　レーザガウジング法は、突合せ溶接用鋼板のアルミニウムめっき層の表面に、レーザビームを照射して突合せ溶接用鋼板を溶融し、アシストガス（空気、不活性ガス等）の動圧により、その溶融生成物を飛散させて鋼板表面をガウジングする加工方法である。具体的には、ラインビームを走査しながら、アシストガスを噴射する。レーザによりアルミニウムめっき層を加熱して突合せ溶接用鋼板を溶融し、溶融生成物をアシストガスで飛散する。 In the laser gouging method, the surface of the aluminum-plated layer of a butt-welding steel sheet is irradiated with a laser beam to melt the butt-welding steel sheet, and the melted product is produced by the dynamic pressure of an assist gas (air, inert gas, etc.). This is a processing method in which the surface of a steel sheet is gouged by scattering. Specifically, the assist gas is injected while scanning the line beam. The aluminum plating layer is heated by a laser to melt the steel sheet for butt welding, and the melt product is scattered by the assist gas.
　アシストガスは溶融生成物を効率よく飛散すればよく、アシストガスを噴射するための噴射ノズル形状および噴射方向（上方、下方、前方、後方、横方、斜方等）、並びに、アシストガスを噴射する位置は、特に限定されるものではない。噴射ノズル形状は目的に応じて適宜選択すればよい。また、アシストガスの噴射方向および噴射位置は、目的に応じて適宜調整してよい。好ましい噴射方法の一例としては、目標とするガウジング幅よりも広いフラットノズルを用い、レーザビームの進行方向の後方から、レーザビームの照射位置に向けて噴射することが挙げられる。 The assist gas only needs to efficiently disperse the melt product, and the injection nozzle shape and injection direction (upper, lower, front, rear, lateral, oblique, etc.) for injecting the assist gas, and the assist gas are injected. The position to do is not particularly limited. The injection nozzle shape may be appropriately selected according to the purpose. Further, the injection direction and the injection position of the assist gas may be appropriately adjusted according to the purpose. As an example of a preferable injection method, a flat nozzle wider than the target gouging width is used, and injection is performed from the rear in the traveling direction of the laser beam toward the irradiation position of the laser beam.
　飛散せずに残存したアルミニウムめっき層の少なくとも一部は、レーザの熱によって金属間化合物層として成長する。その結果、突合せ溶接用鋼板の縁部にレーザガウジング法による処理を施した部分では、金属間化合物層（ＩＭＣ０）よりも厚みが増加して金属間化合物層（ＩＭＣ１）が形成される。なお、レーザガウジング法による処理を施した縁部の一部には、アルミニウムめっき層が残存していてもよい。 At least a part of the aluminum plating layer remaining without scattering grows as an intermetallic compound layer by the heat of the laser. As a result, the intermetallic compound layer (IMC 1 ) is formed in the portion where the edge portion of the butt-welding steel sheet is treated by the laser gouging method, which is thicker than the intermetallic compound layer (IMC 0 ). An aluminum plating layer may remain on a part of the edge portion treated by the laser gouging method.
　なお、金属間化合物層（ＩＭＣ１）を形成するためのレーザガウジング法による好ましい条件の一例としては、以下の条件が挙げられる。
　例えば、アシストガスは、３．０ｋｇｆ／ｃｍ２～７．０ｋｇｆ／ｃｍ２の範囲で噴射することが好ましい。また、半導体レーザの場合、レーザ出力は、０．５ｋＷ～４．０ｋＷの範囲であることが好ましく、レーザ走査速度は、３．０ｍ／ｍｉｎ～７．０ｍ／ｍｉｎの範囲であることが好ましい。このような条件で、溶接予定部の縁部に対してレーザガウジング処理すると、金属間化合物層の厚みが成長し、突合せ溶接用鋼板の縁部に金属間化合物層（ＩＭＣ１）が形成される。 The following conditions can be mentioned as an example of preferable conditions by the laser gouging method for forming the intermetallic compound layer (IMC 1 ).
For example, the assist gas is preferably injected at a range of 3.0kgf / cm 2 ~ 7.0kgf / cm 2. Further, in the case of a semiconductor laser, the laser output is preferably in the range of 0.5 kW to 4.0 kW, and the laser scanning speed is preferably in the range of 3.0 m / min to 7.0 m / min. When laser gouging treatment is performed on the edge of the planned welding portion under such conditions, the thickness of the intermetallic compound layer grows, and the intermetallic compound layer (IMC 1 ) is formed on the edge of the steel plate for butt welding. ..
　突合せ溶接用鋼板の縁部の少なくとも一部に、金属間化合物層（ＩＭＣ１）が形成されていれば、突合せ溶接用鋼板の縁部にレーザガウジング法による処理を施す順序は、上記の形成法Ａに限定されるものではない。
　突合せ溶接用鋼板の縁部の少なくとも一部に、金属間化合物層（ＩＭＣ１）を形成する他の好ましい方法の一例としては、例えば、次の方法が挙げられる。 If an intermetallic compound layer (IMC 1 ) is formed on at least a part of the edge of the butt-welded steel sheet, the order of applying the laser gouging method to the edge of the butt-welded steel sheet is the above-mentioned forming method. It is not limited to A.
As an example of another preferable method for forming the intermetallic compound layer (IMC 1 ) on at least a part of the edge portion of the butt weld steel sheet, for example, the following method can be mentioned.
　突合せ溶接用鋼板の縁部以外の領域の少なくとも一部に、母材鋼板の両面上に形成されたアルミニウムめっき層の表面に対し、レーザガウジング法による処理を施す工程と、レーザガウジング法による処理を施した部分が突合せ溶接用鋼板の縁部に位置するように鋼板を切断する工程とを有していてもよい（形成法Ｂとする）。 A process of applying a laser gouging method to the surface of an aluminum-plated layer formed on both sides of a base steel sheet and a treatment by a laser gouging method are performed on at least a part of a region other than the edge of the butt welding steel sheet. It may have a step of cutting the steel sheet so that the applied portion is located at the edge of the steel plate for butt welding (referred to as forming method B).
　形成法Ｂは、例えば、具体的には、次のような方法である。まず、アルミニウムめっき鋼板に打ち抜き加工を施し、所望の大きさに切断したアルミニウムめっき鋼板を準備する。切断されたアルミニウムめっき鋼板において、縁部以外の領域の少なくとも一部に、母材鋼板上に形成されたアルミニウムめっき層の表面に対し、レーザガウジング法による処理を施す。レーザガウジング法による処理は、アルミニウムめっき鋼板の縁部以外の領域に、例えば一方向に延びるように行う。これにより、レーザガウジング法による処理を施した部分には、例えば一方向に伸びた状態で、金属間化合物層（ＩＭＣ１）が形成される。そして、この金属間化合物層（ＩＭＣ１）が形成された部分が、突合せ溶接用鋼板の縁部に位置するように、アルミニウムめっき鋼板の金属間化合物層（ＩＭＣ１）が形成された部分で切断して、テーラードブランクを形成する前の鋼板とする。 Specifically, the forming method B is, for example, the following method. First, the aluminum-plated steel sheet is punched to prepare an aluminum-plated steel sheet cut to a desired size. In the cut aluminum-plated steel sheet, at least a part of the region other than the edge portion is treated by a laser gouging method on the surface of the aluminum-plated layer formed on the base steel sheet. The treatment by the laser gouging method is performed so as to extend in a region other than the edge of the aluminum-plated steel sheet, for example, in one direction. As a result, an intermetallic compound layer (IMC 1 ) is formed in the portion treated by the laser gouging method, for example, in a state of being extended in one direction. Then, the intermetallic compound layer (IMC 1) there is formed a portion, to be located at the edge of the butt welding steel plates, cut with the intermetallic compound layer of aluminum-plated steel sheet (IMC 1) is formed partially Then, the steel plate before forming the tailored blank is used.
　この場合（形成法Ｂの場合）、レーザガウジング法による処理を施して、アルミニウムめっき鋼板における金属間化合物層（ＩＭＣ１）が形成された部分の幅が、０．４ｍｍ～１０ｍｍであることがよい。この金属間化合物層（ＩＭＣ１）が形成された部分は、目的の幅となるように、金属間化合物層（ＩＭＣ１）が形成された部分の中央線付近の位置で切断してもよく、この部分における中央線付近以外の位置で切断して、突合せ溶接用鋼板を得てもよい。 In this case (in the case of the forming method B), the width of the portion of the aluminum-plated steel sheet on which the intermetallic compound layer (IMC 1 ) is formed by the laser gouging method is preferably 0.4 mm to 10 mm. .. The portion where the intermetallic compound layer (IMC 1 ) is formed may be cut at a position near the center line of the portion where the intermetallic compound layer (IMC 1 ) is formed so as to have a desired width. A steel plate for butt welding may be obtained by cutting at a position other than the vicinity of the center line in this portion.
　なお、上記の形成法Ａで形成した金属間化合物層（ＩＭＣ１）が形成された部分の幅は、突合せ溶接用鋼板を突合せ溶接した後の溶融凝固領域（溶接金属）の幅の半分より２０％から４０％大きいことがよい。
　また、上記の形成法Ｂのように形成した突合せ溶接用鋼板のアルミニウムめっき鋼板における切断前での金属間化合物層（ＩＭＣ１）が形成された部分の幅は、突合せ溶接用鋼板を突合せ溶接した後の溶融凝固領域（溶接金属）の幅の２０％から４０％大きいことがよい。
　これらの範囲であると、突合せ溶接用鋼板を突合せ溶接した後の溶接金属に、アルミニウムが多量に混入することが抑制されるため、ホットスタンプ後のホットスタンプ成形品における引張強度の低下が抑制され得る。 The width of the portion where the intermetallic compound layer (IMC 1 ) formed by the above forming method A is formed is 20 from half the width of the melt-solidified region (welded metal) after the butt-welding steel plate is butt-welded. It should be% to 40% larger.
Further, the width of the portion where the intermetallic compound layer (IMC 1 ) was formed before cutting in the aluminum-plated steel sheet of the butt-welded steel sheet formed as in the above forming method B was obtained by butt-welding the butt-welded steel sheet. It is preferably 20% to 40% larger than the width of the later melt-solidified region (welded metal).
Within these ranges, a large amount of aluminum is suppressed from being mixed into the weld metal after the butt welding steel plate is butt welded, so that a decrease in tensile strength in the hot stamped molded product after hot stamping is suppressed. obtain.
＜テーラードブランク＞
　次に、テーラードブランクについて説明する。
　本開示のテーラードブランクは、溶接金属と、溶接金属に接続する少なくとも２枚の鋼板とを備える。
　そして、少なくとも２つの鋼板部は、前記溶接金属と接続する縁部、及び前記縁部以外の部分を有する。少なくとも２枚の鋼板のうち、少なくとも１枚の鋼板部は、溶接金属と接続する縁部では、前記母材鋼板の両面に、少なくとも鉄及びアルミニウムを含む金属間化合物層が設けられている。縁部以外の部分では、母材鋼板部の両面に、鉄及びアルミニウムを含む金属間化合物層、及びアルミニウムめっき層が当該順で設けられている。
　また、溶接金属と接続する縁部の少なくとも一部の部分における片面あたりのアルミニウムめっき層の厚みをａ１μｍ、及び金属間化合物層（ＩＭＣ１）の厚みをｂ１μｍとし、前記溶接金属と接続する縁部以外の部分における片面あたりのアルミニウムめっき層の厚みをａ０μｍ、及び金属間化合物層（ＩＭＣ０）の厚みをｂ０μｍとし、
　前記縁部以外の部分における母材鋼板の板厚をｔ０μｍとしたとき、
　下記式（１）、下記式（２）及び下記式（３）を満たす。
　式（１）　：　ｂ１（μｍ）＞ｂ０（μｍ）
　式（２）　：　３μｍ≦ｂ０（μｍ）≦１０μｍ
　式（３）　：　０．８％≦｛２×（ａ１（μｍ）＋ｂ１（μｍ））／ｔ０（μｍ）｝×１００≦３．５％
　（ただし、アルミニウムめっき層の厚みａ１は０を含む） <Tailored blank>
Next, the tailored blank will be described.
The tailored blank of the present disclosure includes a weld metal and at least two steel plates connected to the weld metal.
Then, at least two steel plate portions have an edge portion connected to the weld metal and a portion other than the edge portion. Of the at least two steel plates, at least one steel plate portion is provided with an intermetallic compound layer containing at least iron and aluminum on both sides of the base steel plate at the edge portion connected to the weld metal. In the portion other than the edge portion, an intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel plate portion in this order.
Further, the thickness of the aluminum plating layer per one side of at least a part of the edge portion connected to the weld metal is a 1 μm, and the thickness of the intermetallic compound layer (IMC 1 ) is b 1 μm. The thickness of the aluminum-plated layer per surface in the portion other than the connecting edge is a 0 μm, and the thickness of the intermetallic compound layer (IMC 0 ) is b 0 μm.
When the thickness of the base steel plate in the portion other than the edge is t 0 μm,
The following formula (1), the following formula (2) and the following formula (3) are satisfied.
Equation (1): b 1 (μm)> b 0 (μm)
Equation (2): 3 μm ≤ b 0 (μm) ≤ 10 μm
Equation (3): 0.8% ≤ {2 × (a 1 (μm) + b 1 (μm)) / t 0 (μm)} × 100 ≦ 3.5%
(However, the thickness a 1 of the aluminum plating layer includes 0)
　本開示のテーラードブランクは、溶接金属から鋼板部の方向に向かって、溶接金属、溶接金属に接続する縁部、縁部以外の部分がこの順で配置されている。つまり、本開示のテーラードブランクは、本開示の突合せ溶接用鋼板を少なくとも１枚有し、本開示の突合せ溶接用鋼板の金属間化合物層（ＩＭＣ１）を有する縁部を介して、少なくとも２枚の突合せ溶接用鋼板を突合せ溶接した溶接鋼板である。本開示の突合せ溶接用鋼板を少なくとも１枚有していれば、テーラードブランクは、１枚の突合せ溶接用鋼板における金属間化合物層（ＩＭＣ１）を有する縁部の端面と、他の鋼板の縁部の端面とを突合せた状態で溶接した溶接鋼板であってもよい。テーラードブランクは、２枚の突合せ溶接用鋼板における金属間化合物層（ＩＭＣ１）を有する縁部の端面どうしを突合せた状態で溶接してもよく、３枚の鋼板における金属間化合物層（ＩＭＣ１）を有する縁部の端面どうしを突合せた状態で溶接してもよい。すなわち、本開示のテーラードブランクは、本開示の突合せ溶接用鋼板を少なくとも１枚含み、少なくとも２枚の突合せ溶接用鋼板の縁部が対向して配置された突合せ溶接用鋼板と、少なくとも２枚の突合せ溶接用鋼板の縁部を接合する溶接金属とを有している。 In the tailored blank of the present disclosure, the weld metal, the edge portion connected to the weld metal, and the portion other than the edge portion are arranged in this order from the weld metal toward the steel plate portion. That is, the tailored blank of the present disclosure has at least one butt-welded steel sheet of the present disclosure, and at least two of the butt-welded steel sheets of the present disclosure are interposed via an edge having an intermetal compound layer (IMC 1 ). It is a welded steel sheet obtained by butt welding the steel sheets for butt welding. If the tailored blank has at least one butt-welded steel sheet of the present disclosure, the tailored blank is the end face of the edge portion of one butt-welded steel sheet having an intermetallic compound layer (IMC 1 ) and the edge of another steel sheet. It may be a welded steel sheet welded in a state where the end faces of the portions are butted against each other. Tailored blank may be welded in a state of abutting the end surfaces to each other of the edges having the intermetallic compound layer in the two butt welding steel plate (IMC 1), the intermetallic compound layer in the three steel plates (IMC 1 ) May be welded in a state where the end faces of the edges are butted against each other. That is, the tailored blank of the present disclosure includes at least one steel plate for butt welding of the present disclosure, and at least two steel plates for butt welding in which the edges of the two steel plates for butt welding are arranged so as to face each other. It has a weld metal that joins the edges of steel sheets for butt welding.
　テーラードブランクを得るための２枚以上の突合せ溶接用鋼板は、目的に応じて組み合わせて用いればよい。テーラードブランクを得るための２枚以上の突合せ溶接用鋼板は、例えば、それぞれ同じ強度クラスの鋼板を用いてもよく、異なる強度クラスの鋼板を用いてもよい。また、鋼板の厚みが同じ鋼板を用いてもよく、鋼板の厚みが異なる鋼板を用いてもよい。２枚以上の鋼板は、例えば、突合せ溶接用鋼板における各々の金属間化合物層ＩＭＣ１の厚みが同じ鋼板を用いてもよく、ＩＭＣ１の厚みが異なる鋼板を用いてもよい。 Two or more butt-welding steel sheets for obtaining a tailored blank may be used in combination according to the purpose. As the two or more butt welding steel plates for obtaining a tailored blank, for example, steel plates of the same strength class may be used, or steel plates of different strength classes may be used. Further, steel plates having the same thickness may be used, or steel plates having different thicknesses may be used. As the two or more steel plates, for example, steel plates having the same thickness of the intermetallic compound layer IMC 1 in the steel plate for butt welding may be used, or steel plates having different thicknesses of the IMC 1 may be used.
　突合せ溶接を行う溶接方法は特に限定されず、例えば、レーザ溶接（レーザビーム溶接）、アーク溶接、電子ビーム溶接等の溶接方法が挙げられる。また、アーク溶接としては、プラズマ溶接、ＴＩＧ（Ｔｕｎｇｓｔｅｎ　Ｉｎｅｒｔ　Ｇａｓ）溶接、ＭＩＧ（Ｍｅｔａｌ　Ｉｎｅｒｔ　Ｇａｓ）溶接、ＭＡＧ（Ｍｅｔａｌ　Ａｃｔｉｖｅ　Ｇａｓ）溶接等が挙げられ、好適なアーク溶接としては、プラズマ溶接が挙げられる。溶接条件は、使用する突合せ溶接用鋼板の厚み等、目的とする条件によって選択すればよい。
　また、溶接は、必要に応じて、フィラーワイヤを供給しながら溶接してもよい。 The welding method for performing butt welding is not particularly limited, and examples thereof include welding methods such as laser welding (laser beam welding), arc welding, and electron beam welding. Further, examples of the arc welding include plasma welding, TIG (Tungsten Inert Gas) welding, MIG (Metal Inert Gas) welding, MAG (Metal Active Gas) welding, and the like, and examples of suitable arc welding include plasma welding. .. The welding conditions may be selected according to the desired conditions such as the thickness of the butt welding steel sheet to be used.
Further, welding may be performed while supplying a filler wire, if necessary.
　テーラードブランクは、溶接された接合部が、金属間化合物層（ＩＭＣ１）を有する部分に隣接する端面上であることがよい。つまり、テーラードブランクは、金属間化合物層（ＩＭＣ１）が形成されている部分が端面に接して形成されており、この端面どうしを突合せ溶接することにより、接合部が形成されている。 The tailored blank is preferably on the end face where the welded joint is adjacent to the portion having the intermetallic compound layer (IMC 1 ). That is, the tailored blank is formed in which the portion where the intermetallic compound layer (IMC 1 ) is formed is in contact with the end faces, and the joint portion is formed by butt welding the end faces to each other.
　すなわち、テーラードブランクは、少なくとも２枚の突合せ溶接用鋼板と溶接金属とを備えるテーラードブランクであって、本開示の少なくとも１枚の突合せ溶接用鋼板の縁部が対向して配置された突合せ溶接用鋼板と、少なくとも２枚の突合せ溶接用鋼板の縁部の少なくとも一部に隣接して備える溶接金属（つまり、少なくとも２枚の鋼板の縁部を接合する溶接金属）と、を備え、溶接金属に隣接する鋼板の少なくとも一部に、母材鋼板の両面上に少なくとも金属間化合物層（ＩＭＣ１）が形成されているテーラードブランクである。例えば、具体的には、金属間化合物層（ＩＭＣ１）は、溶接金属により接合された２枚の突合せ溶接用鋼板のうち、溶接金属の周囲に位置する両面に有している。 That is, the tailored blank is a tailored blank including at least two butt-welding steel plates and a weld metal, and is for butt-welding in which the edges of at least one butt-welding steel plate of the present disclosure are arranged so as to face each other. A steel plate and a welding metal provided adjacent to at least a part of the edges of at least two butt-welding steel plates (that is, a welding metal for joining the edges of at least two steel plates) are provided in the weld metal. A tailored blank in which at least an intermetallic compound layer (IMC 1 ) is formed on both sides of a base steel plate on at least a part of adjacent steel plates. For example, specifically, the intermetallic compound layer (IMC 1 ) is provided on both sides of the two butt-welding steel sheets joined by the weld metal, which are located around the weld metal.
　ここで、図６を参照して、本開示のテーラードブランクの一例を説明する。図６は本開示のテーラードブランクにおける溶接部の断面の一例を表す模式図である。図６に示すテーラードブランク２００は、同じ種類の２枚の突合せ溶接用鋼板１２０の縁部の端面どうしを突合せ溶接して形成されている。テーラードブランク２００は、２枚の突合せ溶接用鋼板１２０と、２枚の突合せ溶接用鋼板１２０を接合する溶接金属３０とを備えている。２枚の突合せ溶接用鋼板１２０は、それぞれ、縁部以外の領域２６では、母材鋼板１２の両面に、金属間化合物層（ＩＭＣ０）１６Ａとアルミニウムめっき層１４Ａが設けられており、溶接予定部の縁部２２では、母材鋼板１２の両面に金属間化合物層（ＩＭＣ１）１６Ｂが設けられている。金属間化合物層（ＩＭＣ１）１６Ｂは、溶接金属３０に隣接して設けられている。なお、図６に示すテーラードブランク２００は、同じ種類の２枚の突合せ溶接用鋼板１２０の縁部を介して突合せ溶接されているが、本開示のテーラードブランク２００を形成するための突合せ溶接用鋼板は、図６に示す態様に限定されるものではない。 Here, an example of the tailored blank of the present disclosure will be described with reference to FIG. FIG. 6 is a schematic view showing an example of a cross section of a welded portion in the tailored blank of the present disclosure. The tailored blank 200 shown in FIG. 6 is formed by butt-welding the end faces of the edges of two butt-welding steel plates 120 of the same type. The tailored blank 200 includes two butt-welding steel plates 120 and a weld metal 30 for joining two butt-welding steel plates 120. The two butt-welded steel sheets 120 are planned to be welded because the intermetallic compound layer (IMC 0 ) 16A and the aluminum plating layer 14A are provided on both sides of the base steel sheet 12 in the region 26 other than the edge portion, respectively. At the edge portion 22 of the portion, an intermetallic compound layer (IMC 1 ) 16B is provided on both surfaces of the base steel plate 12. The intermetallic compound layer (IMC 1 ) 16B is provided adjacent to the weld metal 30. The tailored blank 200 shown in FIG. 6 is butt-welded through the edges of two butt-welded steel plates 120 of the same type, but the butt-welded steel plate for forming the tailored blank 200 of the present disclosure is formed. Is not limited to the aspect shown in FIG.
　次に、図７及び図８を参照して、テーラードブランクにおける溶接金属中のフェライトの有無について説明する。図７は、２枚の突合せ溶接用鋼板における未処理の縁部を介して形成したテーラードブランクの溶接金属付近における拡大断面写真である。図７中、矢印Ｅは、溶接金属における突合せ溶接用鋼板の縁部周辺にフェライトが存在していることを表す。図７に示すテーラードブランクでは、鋼板から多量に混入したアルミニウム濃度によって、溶接金属中にフェライトの存在が見られると考えられる。一方、図８は、本開示の２枚の突合せ溶接用鋼板における縁部を介して形成したテーラードブランクの溶接金属付近における拡大断面写真である。図８中、矢印Ｎは、溶接金属における突合せ溶接用鋼板の縁部周辺にフェライトの存在がないことを表す。図８に示すテーラードブランクでは、溶接金属に多量に混入するアルミニウム濃度が少ないため、フェライトの存在が見られないと考えられる。 Next, the presence or absence of ferrite in the weld metal in the tailored blank will be described with reference to FIGS. 7 and 8. FIG. 7 is an enlarged cross-sectional photograph of the tailored blank formed through the untreated edges of the two butt-welded steel plates in the vicinity of the weld metal. In FIG. 7, the arrow E indicates that ferrite is present around the edge of the butt-welding steel plate in the weld metal. In the tailored blank shown in FIG. 7, it is considered that the presence of ferrite is observed in the weld metal due to the concentration of aluminum mixed in a large amount from the steel sheet. On the other hand, FIG. 8 is an enlarged cross-sectional photograph of the tailored blank formed in the vicinity of the weld metal of the two butt-welded steel sheets of the present disclosure formed through the edges. In FIG. 8, the arrow N indicates that there is no ferrite around the edge of the butt-welded steel plate in the weld metal. In the tailored blank shown in FIG. 8, it is considered that the presence of ferrite is not observed because the concentration of aluminum mixed in a large amount in the weld metal is small.
＜熱間プレス成形品＞
　次に、熱間プレス成形品について説明する。
　熱間プレス成形品は、溶接金属と、溶接金属に接続する少なくとも２つの鋼板部とを備える。
　そして、少なくとも２つの鋼板部は、溶接金属と接続する縁部、及び前記縁部以外の部分を有する。少なくとも２つの鋼板部のうち、少なくとも１つの鋼板部は、前記溶接金属と接続する縁部では、前記母材鋼板の両面に、少なくとも鉄及びアルミニウムを含む金属間化合物層が設けられている。前記縁部以外の部分では、母材鋼板の両面に、鉄及びアルミニウムを含む金属間化合物層、及びアルミニウムめっき層が当該順で設けられている。
　また、溶接金属と接続する縁部の少なくとも一部の部分における片面あたりのアルミニウムめっき層の厚みをａ２μｍ、及び金属間化合物層（ＩＭＣ２）の厚みをｂ２μｍとし、
　ａ２、及び前記ｂ２の測定位置における母材鋼板の板厚をｔ１μｍとしたとき、
　下記式（４）及び下記式（５）を満たす。
　式（４）　：　０．８％≦｛２×（ａ２（μｍ）＋ｂ２（μｍ））／ｔ１（μｍ）｝×１００≦３．５％　
　式（５）　：１０μｍ≦（ａ２（μｍ）＋ｂ２（μｍ））
　（ただし、アルミニウムめっき層の厚みａ２は０を含む） <Hot press molded product>
Next, the hot press molded product will be described.
The hot press molded product includes a weld metal and at least two steel plate portions connected to the weld metal.
Then, at least two steel plate portions have an edge portion connected to the weld metal and a portion other than the edge portion. Of the at least two steel plate portions, at least one steel plate portion is provided with an intermetallic compound layer containing at least iron and aluminum on both sides of the base steel plate at the edge portion connected to the weld metal. In the portion other than the edge portion, an intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order.
Further, the thickness of the aluminum plating layer per one side at least a part of the edge portion connected to the weld metal is a 2 μm, and the thickness of the intermetallic compound layer (IMC 2 ) is b 2 μm.
When a 2, and the thickness of the base steel sheet at the measurement position of the b 2 was t 1 [mu] m,
The following formula (4) and the following formula (5) are satisfied.
Equation (4): 0.8% ≤ {2 × (a 2 (μm) + b 2 (μm)) / t 1 (μm)} × 100 ≦ 3.5%
Equation (5): 10 μm ≦ (a 2 (μm) + b 2 (μm))
(However, the thickness a 2 of the aluminum plating layer includes 0)
　アルミニウムめっき層の厚みａ２μｍ、及び金属間化合物層（ＩＭＣ２）の厚みｂ２μｍは、アルミニウムめっき層の厚みａ１μｍ、及び金属間化合物層（ＩＭＣ１）の厚みｂ１μｍと同様の判断基準にしたがって、線分析により測定する。線分析は、溶接金属と接続する縁部において、縁部における表面部分から、母材鋼板の表面（母材鋼板と金属間化合物層との境界）までの範囲について行う。測定箇所は、溶接金属と接続する鋼板部において、レーザガウジング処理をされた位置に相当する縁部（つまり、溶接金属と接続する本開示の突合せ溶接用鋼板における金属間化合物層（ＩＭＣ１）が設けられた縁部）を測定する。具体的には、溶接金属と接続するレーザガウジング処理をされた位置に相当する縁部において、溶接金属から縁部以外の部分までの全幅に対して、溶接金属から１０％以内の範囲、及び、縁部以外の部分と縁部との境界から１０％以内の範囲を除いた領域を３等分し、３等分した中央位置で行う。そして、測定した３箇所の平均値とする。一方、母材鋼板の板厚ｔ１μｍについては、熱間プレス成形の影響が少ない箇所を選択して測定することが好ましい。この点で、母材鋼板の板厚ｔ１μｍは、アルミニウムめっき層の厚みａ２μｍ、金属間化合物層（ＩＭＣ２）の厚みｂ２μｍを測定した位置に対応する位置で測定する。母材鋼板の板厚ｔ１μｍの測定は、光学顕微鏡で測定することが好ましい。なお、式（５）で表される値は、溶接部の耐食性に優れる点で、１２μｍ以上であることが好ましい。また、式（５）を満足するのであれば、アルミニウムめっき層の厚みａ２μｍは、０（ゼロ）μｍであってもよく、０μｍを超えていてもよい。例えば、アルミニウムめっき層の厚みａ１μｍ、熱間プレス成形の条件等によって、アルミニウムめっき層の厚みａ２μｍは、０μｍになる場合があり、０μｍを超える場合がある。 The thickness b 2 [mu] m of thickness a 2 [mu] m of the aluminum layer, and the intermetallic compound layer (IMC 2), as well as the thickness b 1 [mu] m of thickness a 1 [mu] m of the aluminum layer, and the intermetallic compound layer (IMC 1) Measure by line analysis according to the criteria of. The line analysis is performed on the edge portion connected to the weld metal from the surface portion at the edge portion to the surface of the base steel plate (the boundary between the base steel plate and the intermetallic compound layer). The measurement location is the edge portion corresponding to the laser gouging position in the steel plate portion connected to the weld metal (that is, the intermetallic compound layer (IMC 1 ) in the butt-welded steel plate connected to the weld metal of the present disclosure). Measure the provided edge). Specifically, in the edge portion corresponding to the position where the laser gouging treatment is performed to connect with the weld metal, the range within 10% from the weld metal and the range within 10% of the total width from the weld metal to the portion other than the edge portion, and The region excluding the range within 10% from the boundary between the portion other than the edge portion and the edge portion is divided into three equal parts, and the treatment is performed at the central position divided into three equal parts. Then, the average value of the three measured points is used. On the other hand, with respect to the plate thickness t 1 μm of the base steel sheet, it is preferable to select and measure a portion that is less affected by hot press forming. In this regard, the thickness t 1 [mu] m of the base material steel plate, the thickness a 2 [mu] m of the aluminum layer, measured at a position corresponding to the measured position and the thickness b 2 [mu] m of the intermetallic compound layer (IMC 2). The base steel plate having a thickness of t 1 μm is preferably measured with an optical microscope. The value represented by the formula (5) is preferably 12 μm or more in terms of excellent corrosion resistance of the welded portion. Also, if satisfying the equation (5), the thickness a 2 [mu] m of the aluminum layer may be 0 (zero) [mu] m, may exceed 0 .mu.m. For example, depending on the thickness of the aluminum plating layer a 1 μm, the conditions of hot press molding, etc., the thickness a 2 μm of the aluminum plating layer may be 0 μm, or may exceed 0 μm.
　本開示の熱間プレス成形品は、溶接金属から鋼板部の方向に向かって、溶接金属、溶接金属に接続する縁部、縁部以外の部分がこの順で配置されている。つまり、本開示の熱間プレス成形品（ホットスタンプ成形品）は、本開示のテーラードブランクに対して熱間プレスして生成される。
　すなわち、ホットスタンプ成形品は、少なくとも２枚の突合せ溶接用鋼板と溶接金属とを備えるホットスタンプ成形品であって、本開示の少なくとも１枚の突合せ溶接用鋼板の縁部が対向して配置された突合せ溶接用鋼板と、少なくとも２枚の突合せ溶接用鋼板の縁部の少なくとも一部に隣接して備える溶接金属（つまり、少なくとも２枚の突合せ溶接用鋼板の縁部を接合する溶接金属）と、を備える。また、ホットスタンプ成形品では、焼入れにより、溶接金属に隣接する突合せ溶接用鋼板において、溶接金属に隣接する縁部の少なくとも一部に、金属間化合物層（ＩＭＣ２）が形成されている。例えば、具体的には、金属間化合物層（ＩＭＣ２）は、溶接金属により接合された２枚の突合せ溶接用鋼板のうち、溶接金属の周囲に位置する両面に有している。なお、焼入れ後により、ホットスタンプ成形品では、溶接金属に接続する溶接用鋼板の縁部におけるアルミニウムめっき層の厚みａ２μｍと金属間化合物層（ＩＭＣ２）の厚みｂ２μｍとの合計の厚みは、縁部以外の部分におけるアルミニウムめっき層の厚みａ０μｍと金属間化合物層（ＩＭＣ０）の厚みｂ０μｍとの合計の厚みよりも小さくなる。 In the hot press-formed product of the present disclosure, the weld metal, the edge portion connected to the weld metal, and the portion other than the edge portion are arranged in this order from the weld metal toward the steel plate portion. That is, the hot press molded product (hot stamp molded product) of the present disclosure is produced by hot pressing the tailored blank of the present disclosure.
That is, the hot stamped product is a hot stamped product including at least two butt-welded steel plates and a weld metal, and the edges of at least one butt-welded steel plate of the present disclosure are arranged so as to face each other. A butt-welded steel plate and a weld metal provided adjacent to at least a part of the edges of at least two butt-welded steel plates (that is, a weld metal that joins the edges of at least two butt-welded steel plates). , Further, in the hot stamped product, an intermetallic compound layer (IMC 2 ) is formed on at least a part of the edge portion adjacent to the weld metal in the butt welding steel sheet adjacent to the weld metal by quenching. For example, specifically, the intermetallic compound layer (IMC 2 ) is provided on both sides of the two butt-welding steel sheets joined by the weld metal, which are located around the weld metal. A more after quenching, hot in the stamping moldings, welding steel plate to be connected to the weld metal thickness a 2 [mu] m and the intermetallic compound layer of the aluminum layer at the edge thickness b 2 [mu] m and the total of (IMC 2) the thickness is smaller than the total thickness of the thickness b 0 [mu] m of the aluminum layer thickness a 0 [mu] m and the intermetallic compound layer in the portion other than the edge (IMC 0).
　ホットスタンプ成形品は、次のようにして製造し得る。
　まず、テーラードブランクを高温に加熱してテーラードブランクを軟化させる。そして、金型を用いて、軟化したテーラードブランクをホットスタンプにより成形および冷却して焼き入れられ、目的とする形状のホットスタンプ成形品が得られる。ホットスタンプ成形品は、加熱、及び冷却により焼入れされることで、例えば、約１５００ＭＰａ以上の高い引張強度を有する成形品が得られる。 The hot stamped product can be manufactured as follows.
First, the tailored blank is heated to a high temperature to soften the tailored blank. Then, using a mold, the softened tailored blank is molded and cooled by hot stamping and then quenched to obtain a hot stamped product having a desired shape. The hot stamp molded product is hardened by heating and cooling to obtain, for example, a molded product having a high tensile strength of about 1500 MPa or more.
　ホットスタンプするときの加熱方法としては、通常の電気炉、ラジアントチューブ炉に加え、赤外線加熱、通電加熱、誘導加熱等による加熱方法を採用することが可能である。 As a heating method for hot stamping, it is possible to adopt a heating method such as infrared heating, energization heating, induction heating, etc., in addition to a normal electric furnace and radiant tube furnace.
　ホットスタンプ成形品は、突合せ溶接用鋼板のアルミニウムめっき層が、加熱時に突合せ溶接用鋼板の腐食および酸化に対する保護を付与する、金属間化合物層に変化させられる。例えば、一例として、アルミニウムめっき層にシリコン（Ｓｉ）を含む場合、アルミニウムめっき層は、加熱されるとＦｅとの相互拡散により、Ａｌ相が、金属間化合物層、すなわち、Ａｌ－Ｆｅ合金相、及びＡｌ－Ｆｅ－Ｓｉ合金相へと変化する。Ａｌ－Ｆｅ合金相及びＡｌ－Ｆｅ－Ｓｉ合金相の融点は高く、１０００℃以上である。Ａｌ－Ｆｅ相及びＡｌ－Ｆｅ－Ｓｉ相は複数種類あり、高温加熱、又は長時間加熱すると、よりＦｅ濃度の高い合金相へと変化していく。これらの金属間化合物層が、突合せ溶接用鋼板の腐食および酸化を防止する。 In the hot stamped product, the aluminum-plated layer of the butt-welded steel sheet is changed to an intermetallic compound layer that provides protection against corrosion and oxidation of the butt-welded steel sheet during heating. For example, when the aluminum plating layer contains silicon (Si), the aluminum plating layer becomes an intermetallic compound layer, that is, an Al—Fe alloy phase, due to mutual diffusion with Fe when heated. And change to an Al—Fe—Si alloy phase. The melting points of the Al—Fe alloy phase and the Al—Fe—Si alloy phase are high, 1000 ° C. or higher. There are a plurality of types of Al—Fe phase and Al—Fe—Si phase, and when heated at a high temperature or for a long time, the phase changes to an alloy phase having a higher Fe concentration. These intermetallic compound layers prevent corrosion and oxidation of butt weld steel sheets.
　また、溶接金属には、突合せ溶接用鋼板の縁部の少なくとも一部に形成されている金属間化合物層（ＩＭＣ１）（又は、金属間化合物層（ＩＭＣ１）およびアルミニウムめっき層）に起因するアルミニウムが適度に混入しているため、上記と同様の合金相（金属間化合物層）を含む。特に、溶接金属の表面に上記の合金層を有することで、溶接金属の表面にスケールの発生が抑制される。その結果、溶接金属の表面で化成処理性が向上し、塗料の付着性が向上する。それにより、溶接部は、塗装後耐食性に優れると考えられる。 Further, the weld metal is caused by the intermetallic compound layer (IMC 1 ) (or the intermetallic compound layer (IMC 1 ) and the aluminum plating layer) formed on at least a part of the edge of the steel plate for butt welding. Since aluminum is appropriately mixed, it contains an alloy phase (intermetallic compound layer) similar to the above. In particular, by having the above alloy layer on the surface of the weld metal, the generation of scale on the surface of the weld metal is suppressed. As a result, the chemical conversion treatment property is improved on the surface of the weld metal, and the adhesiveness of the paint is improved. As a result, the welded portion is considered to have excellent corrosion resistance after painting.
　ホットスタンプ成形品として好ましいアルミニウムめっき層の状態は、表面まで合金化された状態で（表面まで金属間化合物層になった状態で）、かつ、合金相中のＦｅ濃度が高くない状態である。合金化されていないＡｌが残存すると、この部位のみが急速に腐食して、塗装後耐食性が劣化し、塗膜膨れが極めて起こりやすくなるため好ましくない。一方、合金相中のＦｅ濃度が高くなり過ぎると、合金相自体の耐食性が低下して、塗装後耐食性が劣化し、塗膜膨れが起こりやすくなる。即ち、合金相の耐食性は、合金相中のＡｌ濃度に依存する。従って、塗装後耐食性を向上させるには、合金化の状態をＡｌ付着量と加熱条件で制御する。 The preferable state of the aluminum plating layer as a hot stamp molded product is a state in which the surface is alloyed (a state in which the surface is an intermetallic compound layer) and the Fe concentration in the alloy phase is not high. If unalloyed Al remains, only this portion is rapidly corroded, the corrosion resistance after coating is deteriorated, and the coating film swelling is extremely likely to occur, which is not preferable. On the other hand, if the Fe concentration in the alloy phase becomes too high, the corrosion resistance of the alloy phase itself deteriorates, the corrosion resistance after coating deteriorates, and the coating film swells easily. That is, the corrosion resistance of the alloy phase depends on the Al concentration in the alloy phase. Therefore, in order to improve the corrosion resistance after painting, the alloying state is controlled by the amount of Al adhered and the heating conditions.
　ホットスタンプするときの最高到達温度については、特に限定されず、例えば、８５０℃～１０００℃とすることが好ましい。ホットスタンプ成形において、最高到達温度は、オーステナイト領域で加熱する必要があることから、通常９００℃～９５０℃程度の温度が採用されることが多い。 The maximum temperature reached during hot stamping is not particularly limited, and is preferably 850 ° C to 1000 ° C, for example. In hot stamping, the maximum temperature reached is usually about 900 ° C. to 950 ° C. because it is necessary to heat in the austenite region.
　ホットスタンプでは、高温に加熱したテーラードブランクを、水冷等により冷却された金型でプレス成形すると同時に、金型での冷却によって焼入れられる。また、必要に応じて金型の隙間から水をブランク材に直接噴霧して水冷してもよい。そして、目的とする形状のホットスタンプ成形品が得られる。 In hot stamping, a tailored blank heated to a high temperature is press-molded with a mold cooled by water cooling or the like, and at the same time, it is quenched by cooling with the mold. Further, if necessary, water may be sprayed directly onto the blank material through the gap of the mold to cool the blank material. Then, a hot stamp molded product having a desired shape can be obtained.
　テーラードブランクが高温に加熱されると、母材鋼板の金属組織は、少なくとも一部、好ましくは全体がオーステナイト単相の組織となる。その後、金型でプレス加工される際に、目的とする冷却条件で冷却することで、オーステナイトを、マルテンサイトおよびベイナイトの少なくとも一方に変態させる。そして、得られたホットスタンプ成形品では、母材鋼板の金属組織が、マルテンサイト、ベイナイト、又はマルテンサイト－ベイナイトのいずれかの金属組織となる。 When the tailored blank is heated to a high temperature, the metal structure of the base steel sheet becomes at least a part, preferably the whole, austenite single-phase structure. Then, when pressed in a die, austenite is transformed into at least one of martensite and bainite by cooling under the desired cooling conditions. Then, in the obtained hot stamped product, the metal structure of the base steel sheet becomes one of martensite, bainite, or martensite-bainite.
　ここで、突合せ溶接用鋼板の製造からホットスタンプ成形品を製造するまでの工程の一例は、次の通りである。
　まず、母材鋼板の両面に、アルミニウムめっき層を形成してアルミニウムめっき鋼板を得る。このとき、母材鋼板とアルミニウムめっき層との間には、金属間化合物層が形成される。
　次に、このアルミニウムめっき鋼板の少なくとも一部の縁部において、レーザガウジング処理により金属間化合物層を成長させる。このとき、アルミニウムめっき層が全て金属間化合物層に変化してもよく、一部のアルミニウムめっき層が金属間化合物層に変化せず、アルミニウムめっき層のまま残存していてもよい。 Here, an example of the process from the production of the steel plate for butt welding to the production of the hot stamped product is as follows.
First, an aluminum-plated layer is formed on both sides of the base steel sheet to obtain an aluminum-plated steel sheet. At this time, an intermetallic compound layer is formed between the base steel plate and the aluminum plating layer.
Next, an intermetallic compound layer is grown by laser gouging treatment at at least a part of the edge of the aluminum-plated steel sheet. At this time, all the aluminum plating layers may be changed to intermetallic compound layers, or some aluminum plating layers may not be changed to intermetallic compound layers and may remain as aluminum plating layers.
　なお、母材鋼板の両面に、アルミニウムめっきを施した鋼板は、コイル状に巻き取られる。
　次に、コイル状に巻かれた鋼板を引き出し、打ち抜き加工を施して打ち抜き鋼板を得る。 The steel plate having aluminum plating on both sides of the base steel plate is wound into a coil.
Next, the steel sheet wound in a coil shape is pulled out and punched to obtain a punched steel sheet.
　ここで、アルミニウムめっき鋼板の縁部の少なくとも一部へのレーザガウジング処理は、アルミニウムめっき鋼板をコイル状に巻き取った後、コイル状に巻かれたアルミニウムめっき鋼板を引き出した状態で形成してもよい。この場合、レーザガウジング処理したあと、レーザガウジング処理した領域が、突合せ溶接用鋼板の縁部となるように打ち抜き加工を施して打ち抜き鋼板を得る。
　また、アルミニウムめっき鋼板の縁部の少なくとも一部へのレーザガウジング処理は、コイル状に巻かれたアルミニウムめっき鋼板を引き出して、打ち抜き加工を施して打ち抜き鋼板を形成した後に行ってもよい。この場合、打ち抜き鋼板の縁部の少なくとも一部にレーザガウジング処理を施してもよい。又は、打ち抜き鋼板の縁部以外の部分に、例えば一方向に延びて金属間化合物層（ＩＭＣ１）が形成されるように、レーザガウジング処理を施した後、レーザガウジング処理を施した領域が突合せ溶接用鋼板の縁部となるように、打ち抜き鋼板のレーザガウジング処理を施した領域を切断してもよい。 Here, the laser gouging treatment on at least a part of the edge of the aluminum-plated steel sheet may be formed in a state where the aluminum-plated steel sheet is wound into a coil and then the coiled aluminum-plated steel sheet is pulled out. Good. In this case, after the laser gouging treatment, a punching process is performed so that the laser gouging treated region becomes the edge portion of the butt welding steel sheet to obtain a punched steel sheet.
Further, the laser gouging treatment on at least a part of the edge portion of the aluminum-plated steel sheet may be performed after the aluminum-plated steel sheet wound in a coil shape is pulled out and punched to form the punched steel sheet. In this case, laser gouging treatment may be applied to at least a part of the edge of the punched steel sheet. Alternatively, after laser gouging treatment is performed so that an intermetallic compound layer (IMC 1 ) is formed in a portion other than the edge of the punched steel sheet, for example, the regions that have been subjected to laser gouging treatment are butted. The laser gouged region of the punched steel sheet may be cut so as to be the edge of the steel sheet for welding.
　次に、突合せ溶接用鋼板の縁部の少なくとも一部に、レーザガウジング処理が施された打ち抜き鋼板を少なくとも１枚準備する。打ち抜き鋼板は、必要に応じて、２枚以上であってもよい。
　次に、レーザガウジング処理が施された縁部を有する端面どうしを突合せて突合わせ溶接を行い、テーラードブランクを得る。 Next, at least one punched steel sheet that has been subjected to laser gouging treatment is prepared at least a part of the edge portion of the butt welding steel sheet. The number of punched steel plates may be two or more, if necessary.
Next, end faces having laser gouging-treated edges are butt-welded and butt-welded to obtain a tailored blank.
　次に、加熱炉で、テーラードブランクを加熱する。
　次に、上型及び下型の一対の金型により、加熱されたテーラードブランクをプレスし、成形及び焼入れする。
　そして、金型から取り外すことで、目的とするホットスタンプ成形品が得られる。 Next, the tailored blank is heated in a heating furnace.
Next, the heated tailored blank is pressed, molded and hardened by a pair of upper and lower dies.
Then, by removing it from the mold, the desired hot stamp molded product can be obtained.
＜鋼管＞
　次に、鋼管について説明する。
　鋼管は、溶接金属と、周方向の２つの縁部が互いに対向するオープン管状に形成され、溶接金属に、周方向の２つの縁部が接続する鋼板部とを備える。
　そして、鋼板部は、少なくとも１つの鋼板部を有し、少なくとも１つの鋼板部は、前記溶接金属と接続する縁部、及び前記縁部以外の部分を有する。少なくとも１つの鋼板部は、前記溶接金属と接続する縁部では、母材鋼板の両面に、少なくとも鉄及びアルミニウムを含む金属間化合物層が設けられている。縁部以外の部分では、母材鋼板の両面に、鉄及びアルミニウムを含む金属間化合物層、及びアルミニウムめっき層が当該順で設けられている。
　また、溶接金属と接続する縁部の少なくとも一部の部分における片面あたりのアルミニウムめっき層の厚みをａ１μｍ、及び金属間化合物層（ＩＭＣ１）の厚みをｂ１μｍとし、
　溶接金属と接続する縁部以外の部分における片面あたりのアルミニウムめっき層の厚みをａ０μｍ、及び金属間化合物層（ＩＭＣ０）の厚みをｂ０μｍとし、
　母材鋼板の板厚をｔ０μｍとしたとき、
　下記式（１）、下記式（２）及び下記式（３）を満たす。
　式（１）　：　ｂ１（μｍ）＞ｂ０（μｍ）
　式（２）　：　３μｍ≦ｂ０（μｍ）≦１０μｍ
　式（３）　：　０．８％≦｛２×（ａ１（μｍ）＋ｂ１（μｍ））／ｔ０（μｍ）｝×１００≦３．５％
　（ただし、アルミニウムめっき層の厚みａ１は０を含む） <Steel pipe>
Next, the steel pipe will be described.
The steel pipe includes a weld metal and a steel plate portion formed in an open tubular shape in which two peripheral edges face each other, and the two peripheral edges are connected to the weld metal.
The steel plate portion has at least one steel plate portion, and the at least one steel plate portion has an edge portion connected to the weld metal and a portion other than the edge portion. At least one steel plate portion is provided with an intermetallic compound layer containing at least iron and aluminum on both sides of the base steel plate at the edge portion connected to the weld metal. In the portion other than the edge portion, an intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order.
Further, the thickness of the aluminum plating layer per one side at least a part of the edge connected to the weld metal is a 1 μm, and the thickness of the intermetallic compound layer (IMC 1 ) is b 1 μm.
The thickness of the aluminum-plated layer per side of the portion other than the edge connected to the weld metal is a 0 μm, and the thickness of the intermetallic compound layer (IMC 0 ) is b 0 μm.
When the thickness of the base steel plate is t 0 μm,
The following formula (1), the following formula (2) and the following formula (3) are satisfied.
Equation (1): b 1 (μm)> b 0 (μm)
Equation (2): 3 μm ≤ b 0 (μm) ≤ 10 μm
Equation (3): 0.8% ≤ {2 × (a 1 (μm) + b 1 (μm)) / t 0 (μm)} × 100 ≦ 3.5%
(However, the thickness a 1 of the aluminum plating layer includes 0)
　つまり、鋼管は、本開示の突合せ溶接用鋼板を含むものであり、溶接金属と、金属間化合物層（ＩＭＣ１）が設けられている縁部を有する部分とが接続されている。そして、本開示の鋼管は、溶接金属から鋼板部の方向に向かって、溶接金属、溶接金属に接続する縁部、縁部以外の部分がこの順で配置されている。すなわち、鋼管は、溶接金属（つまり、鋼板のオープン管の縁部を接合する溶接金属）を少なくとも一つ有し、溶接金属に隣接する本開示の突合せ溶接用鋼板（又はテーラードブランク）による管状体の両面に、金属間化合物層（ＩＭＣ１）を有する。 That is, the steel pipe includes the steel plate for butt welding of the present disclosure, and the weld metal and the portion having the edge portion provided with the intermetallic compound layer (IMC 1 ) are connected. Then, in the steel pipe of the present disclosure, the weld metal, the edge portion connected to the weld metal, and the portion other than the edge portion are arranged in this order from the weld metal toward the steel plate portion. That is, the steel pipe has at least one weld metal (that is, the weld metal that joins the edges of the open pipes of the steel plate), and is a tubular body made of the butt weld steel plate (or tailored blank) of the present disclosure adjacent to the weld metal. It has an intermetallic compound layer (IMC 1 ) on both sides of the above.
　鋼管は、例えば、次のようにして得られた態様が挙げられる。
　１）第１の縁部に、第１の金属間化合物層（ＩＭＣ１）を設け、第２の縁部に、第２の金属間化合物層（ＩＭＣ１）を設けた突合せ溶接用鋼板を１枚準備する。この１枚の突合せ溶接用鋼板を管状に成形してオープン管とする。その後、得られたオープン管において、第１の金属間化合物層（ＩＭＣ１）を備える縁部の端面と、第２の金属間化合物層（ＩＭＣ１）を備える縁部の端面とを突合せた状態で溶接して得られた鋼管でもよい。
　２）第１の縁部に、第１の金属間化合物層（ＩＭＣ１）を設け、第２の縁部に、第２の金属間化合物層（ＩＭＣ１）を設けた突合せ溶接用鋼板を２枚以上準備する。この突合せ溶接用鋼板が２枚である場合は、第１の金属間化合物層（ＩＭＣ１）を備える第１の突合せ溶接用鋼板の縁部の端面と、第２の金属間化合物層（ＩＭＣ１）を備える縁部の第２の突合せ溶接用鋼板の端面とを、突合せた状態で溶接してテーラードブランクとする。そして、このテーラードブランクを管状に成形してオープン管とする。その後、得られたオープン管において、溶接を行っていない第２の金属間化合物層（ＩＭＣ１）を備える第１の突合せ溶接用鋼板での縁部の端面と、溶接を行っていない第１の金属間化合物層（ＩＭＣ１）を備える第２の突合せ溶接用鋼板での縁部の端面とを突合せた状態で溶接して得られた鋼管でもよい。なお、オープン管は、オープン管を形成する前のテーラードブランクにおける溶接線に対して、平行に沿う方向に湾曲させて形成してもよく、交差する方向に湾曲させて形成してもよい。 Examples of the steel pipe include aspects obtained as follows.
1) the first edge, the first intermetallic compound layer (IMC 1) provided, on the second edge, the second intermetallic compound layer welding steel plate butt provided (IMC 1) 1 Prepare a sheet. This single steel plate for butt welding is formed into a tubular shape to form an open pipe. Then, in the obtained open pipe, the end face of the edge portion provided with the first intermetallic compound layer (IMC 1 ) and the end face of the edge portion provided with the second intermetallic compound layer (IMC 1 ) are butted against each other. It may be a steel pipe obtained by welding with.
2) the first edge, the first intermetallic compound layer (IMC 1) provided, on the second edge, the second intermetallic compound layer welding steel plate butt provided (IMC 1) 2 Prepare more than one sheet. When there are two steel plates for butt welding, the end face of the edge of the first steel plate for butt welding provided with the first intermetallic compound layer (IMC 1 ) and the second intermetallic compound layer (IMC 1). ) Is welded to the end face of the second butt-welding steel plate of the edge portion in the butt state to obtain a tailored blank. Then, this tailored blank is formed into a tubular shape to form an open tube. After that, in the obtained open pipe, the end face of the edge portion of the first butt-welded steel plate provided with the second unwelded compound layer (IMC 1 ) and the first unwelded steel sheet. It may be a steel pipe obtained by welding in a state where the end face of the edge portion of the second butt welding steel plate provided with the intermetal compound layer (IMC 1 ) is butt-welded. The open pipe may be formed by being curved in a direction parallel to the welding line in the tailored blank before forming the open pipe, or may be formed by being curved in a direction of intersection.
　ここで、図９及び図１０を参照して、本開示の鋼管を説明する。図９は本開示の鋼管の一例を表す概略模式図である。図９に示す鋼管４１０は、１枚の突合せ溶接用鋼板から形成されている態様を表している。鋼管４１０は、溶接金属３０に隣接して、第１の金属間化合物層（ＩＭＣ１）１６Ｄと、第２の金属間化合物層（ＩＭＣ１）１６Ｅとを備えている。鋼管４１０を形成するための１枚の鋼板は、突合せ溶接用鋼板の両縁部に金属間化合物層（ＩＭＣ１）が形成され、アルミニウムめっき層が除去されている。突合せ溶接用鋼板の第１の縁部では、第１の金属間化合物層（ＩＭＣ１）１６Ｄが形成され、第２の縁部には、第２の金属間化合物層（ＩＭＣ１）１６Ｅが形成されている。そして、鋼管４１０は、１枚の突合せ溶接用鋼板をオープン管とし、第１の金属間化合物層（ＩＭＣ１）１６Ｄを備える第１の縁部の端面と、第２の金属間化合物層（ＩＭＣ１）１６Ｅを備える第２の縁部の端面とを突合せた状態で溶接されることにより形成されている。 Here, the steel pipe of the present disclosure will be described with reference to FIGS. 9 and 10. FIG. 9 is a schematic schematic view showing an example of the steel pipe of the present disclosure. The steel pipe 410 shown in FIG. 9 represents an aspect formed from one steel plate for butt welding. The steel pipe 410 is provided with a first intermetallic compound layer (IMC 1 ) 16D and a second intermetallic compound layer (IMC 1 ) 16E adjacent to the weld metal 30. In one steel plate for forming the steel pipe 410, an intermetallic compound layer (IMC 1 ) is formed on both edges of the steel plate for butt welding, and the aluminum plating layer is removed. A first intermetallic compound layer (IMC 1 ) 16D is formed at the first edge of the butt weld steel sheet, and a second intermetallic compound layer (IMC 1 ) 16E is formed at the second edge. Has been done. The steel pipe 410 uses one steel plate for butt welding as an open pipe, and has an end face of a first edge portion provided with a first intermetallic compound layer (IMC 1 ) 16D and a second intermetallic compound layer (IMC). 1 ) It is formed by welding in a state where it is abutted against the end face of the second edge portion provided with 16E.
　図１０は本開示の鋼管の他の一例を表す概略模式図である。図１０に示す鋼管４２０は、第１の突合せ溶接用鋼板と第２の突合せ溶接用鋼板の２枚の鋼板を有するテーラードブランクから形成された態様を表している。鋼管４２０は、溶接金属３０に隣接して、第１の鋼板における第２の金属間化合物層（ＩＭＣ１）１６Ｈと、第２の鋼板における第１の金属間化合物層（ＩＭＣ１）１６Ｊとを備えている。鋼管４２０を形成するためのテーラードブランクは、第１の突合せ溶接用鋼板における第１の金属間化合物層（ＩＭＣ１）１６Ｆが形成されている端面と、第１の突合せ溶接用鋼板における第１の金属間化合物層（ＩＭＣ１）１６Ｇが形成されている端面とを突合せ溶接することにより形成されている。このテーラードブランクは、２枚のそれぞれの突合せ溶接用鋼板において、それぞれの突合せ溶接用鋼板の２つの縁部に金属間化合物層（ＩＭＣ１）が形成され、アルミニウムめっき層が除去されている。鋼管４２０は、このテーラードブランクの溶接線に対して垂直な方向に湾曲させてオープン管とし、溶接されていない第１の突合せ溶接用鋼板における第２の金属間化合物層（ＩＭＣ１）１６Ｈを備える縁部の端面と、第２の突合せ溶接用鋼板における第１の金属間化合物層（ＩＭＣ１）１６Ｊを備える縁部の端面とを溶接することにより形成されている。 FIG. 10 is a schematic schematic view showing another example of the steel pipe of the present disclosure. The steel pipe 420 shown in FIG. 10 represents an aspect formed from a tailored blank having two steel plates, a first steel plate for butt welding and a second steel plate for butt welding. The steel pipe 420 has a second intermetallic compound layer (IMC 1 ) 16H in the first steel plate and a first intermetallic compound layer (IMC 1 ) 16J in the second steel plate adjacent to the weld metal 30. I have. The tailored blank for forming the steel pipe 420 includes an end face on which the first intermetallic compound layer (IMC 1 ) 16F of the first butt-welded steel plate is formed and a first butt-welded steel plate. It is formed by butt welding with the end face on which the intermetallic compound layer (IMC 1 ) 16G is formed. In this tailored blank, an intermetallic compound layer (IMC 1 ) is formed on the two edges of each of the two butt-welded steel sheets, and the aluminum plating layer is removed. The steel pipe 420 is curved in a direction perpendicular to the welding line of the tailored blank to form an open pipe, and includes a second intermetallic compound layer (IMC 1 ) 16H in the unwelded first butt-welded steel sheet. It is formed by welding the end face of the edge portion and the end face of the edge portion of the second steel plate for butt welding provided with the first intermetallic compound layer (IMC 1 ) 16J.
　テーラードブランクから鋼管を形成する場合、鋼管を形成するためのテーラードブランクを形成する２枚以上の突合せ溶接用鋼板は、目的に応じて組み合わせて用いればよい。２枚以上の突合せ溶接用鋼板の組み合わせは、例えば、前述のテーラードブランクを形成するための突合せ溶接用鋼板で説明した鋼板と同様の組み合わせが挙げられる。 When forming a steel pipe from a tailored blank, two or more butt-welding steel plates forming the tailored blank for forming the steel pipe may be used in combination according to the purpose. Examples of the combination of two or more butt-welding steel sheets include the same combination as the steel sheet described in the above-mentioned butt-welding steel sheet for forming a tailored blank.
　なお、管状に成形する方法は、特に限定されず、例えば、ＵＯＥ法、ベンディングロール法などのいずれの方法でもよい。
　また、管状に成形した後の溶接は、特に限定されず、例えば、レーザ溶接；プラズマ溶接；電気抵抗溶接または高周波誘導加熱溶接により溶接する電縫溶接が挙げられる。 The method of forming into a tubular shape is not particularly limited, and for example, any method such as a UOE method or a bending roll method may be used.
Further, the welding after forming into a tubular shape is not particularly limited, and examples thereof include electric stitch welding in which welding is performed by laser welding; plasma welding; electric resistance welding or high frequency induction heating welding.
＜中空状焼入れ成形品＞
　次に、中空状焼入れ成形品について説明する。
　中空状焼入れ成形品は、溶接金属と、周方向の２つの縁部が互いに対向するオープン管状に形成され、前記溶接金属に、前記周方向の２つの縁部が接続する鋼板部とを備える。
　そして、鋼板部は、少なくとも１つの鋼板部を有し、少なくとも１つの鋼板部は、溶接金属と接続する縁部、及び前記縁部以外の部分を有する。少なくとも１枚の鋼板部は、溶接金属と接続する縁部では、母材鋼板の両面に、少なくとも鉄及びアルミニウムを含む金属間化合物層が設けられており、前記縁部以外の部分では、母材鋼板の両面に、鉄及びアルミニウムを含む金属間化合物層、及びアルミニウムめっき層が当該順で設けられている。
　また、前記溶接金属と接続する縁部の少なくとも一部の部分における片面あたりのアルミニウムめっき層の厚みをａ２μｍ、及び金属間化合物層（ＩＭＣ２）の厚みをｂ２μｍとし、
　前記ａ２、及び前記ｂ２の測定位置における母材鋼板の板厚をｔ１μｍとしたとき、
　下記式（４）及び下記式（５）を満たす。
　式（４）　：　０．８％≦｛２×（ａ２（μｍ）＋ｂ２（μｍ））／ｔ１（μｍ）｝×１００≦３．５％　
　式（５）　：１０μｍ≦（ａ２（μｍ）＋ｂ２（μｍ））
　（ただし、アルミニウムめっき層の厚みａ２は０を含む） <Hollow quenching molded product>
Next, a hollow hardened molded product will be described.
The hollow hardened molded product includes a weld metal and a steel plate portion formed in an open tubular shape in which two peripheral edges face each other and to which the two peripheral edges are connected to the weld metal.
The steel plate portion has at least one steel plate portion, and the at least one steel plate portion has an edge portion connected to the weld metal and a portion other than the edge portion. At least one steel plate portion is provided with an intermetallic compound layer containing at least iron and aluminum on both sides of the base metal steel plate at the edge portion connected to the weld metal, and the base material is provided at a portion other than the edge portion. An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the steel sheet in this order.
Further, the thickness of the aluminum plating layer per one side at least a part of the edge portion connected to the weld metal is a 2 μm, and the thickness of the intermetallic compound layer (IMC 2 ) is b 2 μm.
When the a 2, and the thickness of the base steel sheet at the measurement position of the b 2 was t 1 [mu] m,
The following formula (4) and the following formula (5) are satisfied.
Equation (4): 0.8% ≤ {2 × (a 2 (μm) + b 2 (μm)) / t 1 (μm)} × 100 ≦ 3.5%
Equation (5): 10 μm ≦ (a 2 (μm) + b 2 (μm))
(However, the thickness a 2 of the aluminum plating layer includes 0)
　中空状焼入れ成形品（以下、「中空状ホットスタンプ成形品」と称する場合がある。）は、本開示の突合せ溶接用鋼板、又は本開示の突合せ溶接用鋼板を突合せ溶接して得られたテーラードブランクから形成した鋼管を、焼入れして得られた中空状の成形品である。本開示の中空状焼入れ成形品は、溶接金属から鋼板部の方向に向かって、溶接金属、溶接金属に接続する縁部、縁部以外の部分がこの順で配置されている。
　すなわち、鋼管をホットスタンプすることにより得られた中空状ホットスタンプ成形品は、溶接金属（つまり、鋼板の縁部を接合する溶接金属）を少なくとも一つを有する。また、中空状ホットスタンプ成形品では、焼入れにより、溶接金属に隣接する本開示の突合せ溶接用鋼板の縁部において、中空状ホットスタンプ成形品の両面に、金属間化合物層（ＩＭＣ２）を有する。アルミニウムめっき層の厚みａ２μｍ、金属間化合物層（ＩＭＣ２）の厚みｂ２μｍ、及びａ２、及びｂ２の測定位置における母材鋼板の板厚ｔ１μｍの測定方法は、前述のとおりである。なお、焼入れ後により、中空状ホットスタンプ成形品では、溶接金属に接続する溶接用鋼板の縁部におけるアルミニウムめっき層の厚みａ２μｍと金属間化合物層（ＩＭＣ２）の厚みｂ２μｍとの合計の厚みは、縁部以外の部分におけるアルミニウムめっき層の厚みａ０μｍと金属間化合物層（ＩＭＣ０）の厚みｂ０μｍとの合計の厚みよりも小さくなる。 The hollow hardened molded product (hereinafter, may be referred to as “hollow hot stamp molded product”) is a tailored product obtained by butt welding the butt welding steel plate of the present disclosure or the butt welding steel plate of the present disclosure. It is a hollow molded product obtained by quenching a steel pipe formed from a blank. In the hollow hardened molded product of the present disclosure, the weld metal, the edge portion connected to the weld metal, and the portion other than the edge portion are arranged in this order from the weld metal toward the steel plate portion.
That is, the hollow hot stamped product obtained by hot stamping the steel pipe has at least one weld metal (that is, the weld metal that joins the edges of the steel plate). Further, the hollow hot stamped product has intermetallic compound layers (IMC 2 ) on both sides of the hollow hot stamped product at the edge of the butt-welded steel plate of the present disclosure adjacent to the weld metal by quenching. .. The thickness a 2 [mu] m of the aluminum layer, the thickness b 2 [mu] m, and a 2, and measurement of the thickness t 1 [mu] m of the base material steel plate at the measurement position of the b 2 The method of the intermetallic compound layer (IMC 2) are described above That's right. A more after quenching, the hollow hot stamping molded article, the welding steel plates connected to the weld metal aluminum layer thickness a 2 [mu] m and the intermetallic compound layer at the edge thickness b 2 [mu] m and of (IMC 2) the total thickness is smaller than the total thickness of the thickness b 0 [mu] m of the aluminum layer thickness a 0 [mu] m and the intermetallic compound layer in the portion other than the edge (IMC 0).
　中空状ホットスタンプ成形品は、例えば、以下のようにして得られる。
　本開示の突合せ溶接用鋼板を用いて得られた鋼管を、ベンダーで成形する。次に、加熱炉、通電加熱、または高周波誘導加熱により鋼管を加熱する。鋼管を加熱する温度としては、オーステナイト領域とする必要があることから、例えば、８５０℃～１０００℃とすることがよく、９００℃～９５０℃程度の温度としてもよい。次に、加熱した鋼管を、水冷等により冷却し、焼入れを行う。
　なお、成形と焼入れとは、同時に行ってもよい。これは３次元熱間曲げ焼き入れ（３ＤＱ）と呼ばれ、例えば、鋼管を加熱するとともに、荷重を加えて変形させ、直後に水冷等により冷却することによって焼入れられる。これらの過程を経ることによって、目的とする中空状ホットスタンプ成形品が得られる。なお、中空状ホットスタンプ成形品は、そのまま部品として用いてもよい。 The hollow hot stamp molded product is obtained, for example, as follows.
A steel pipe obtained by using the butt welding steel plate of the present disclosure is formed by a bender. Next, the steel pipe is heated by a heating furnace, energization heating, or high frequency induction heating. Since the temperature for heating the steel pipe needs to be in the austenite region, it may be, for example, 850 ° C to 1000 ° C, or 900 ° C to 950 ° C. Next, the heated steel pipe is cooled by water cooling or the like and quenched.
Note that molding and quenching may be performed at the same time. This is called three-dimensional hot bending quenching (3DQ). For example, a steel pipe is hardened by heating it, deforming it by applying a load, and immediately cooling it by water cooling or the like. By going through these processes, the desired hollow hot stamped product can be obtained. The hollow hot stamped product may be used as it is as a part.
　本開示の中空状ホットスタンプ成形品の用途としては特に限定されず、例えば、自動車車体等の各種自動車部材、産業機械の各種部材が挙げられる。自動車用部材としては、例えば、具体的には、各種ピラー；スタビライザー、ドアビーム、ルーフレール、バンパーなどのレインフォース類；フレーム類；アーム類等の各種部品が挙げられる。 The application of the hollow hot stamp molded product of the present disclosure is not particularly limited, and examples thereof include various automobile members such as automobile bodies and various members of industrial machines. Specific examples of automobile members include various pillars; reinforcements such as stabilizers, door beams, roof rails and bumpers; frames; and various parts such as arms.
　以下、本開示の実施例を例示するが、本開示は以下の実施例には限定されない。
　なお、当業者であれば、特許請求の範囲に記載された思想の範疇内において、各種の変更例または修正例に想到し得ることは明らかであり、それらについても当然に本開示の技術的範囲に属するものと了解される。 Hereinafter, examples of the present disclosure will be illustrated, but the present disclosure is not limited to the following examples.
It is clear that a person skilled in the art can come up with various modifications or amendments within the scope of the ideas described in the claims, and of course, these are also the technical scope of the present disclosure. It is understood that it belongs to.
＜実施例＞
　試験に用いるための突合せ溶接用鋼板に適用する鋼板として、下記の鋼板を準備した。
　準備した鋼板は、ホットスタンプ後の強度クラスが１４７０ＭＰａ級鋼板であり、１辺１０ｃｍの四角形であり、板厚１．６ｍｍである母材鋼板に、アルミニウムめっきが施された鋼板である。この鋼板のアルミニウムめっき層の厚み、及び金属間化合物層の厚みは、表２の縁部以外の領域欄に示すとおりである。なお、各アルミニウムめっき鋼板に用いた母材鋼板における化学組成は表１に示すとおりである。また、表２に示す板厚は、母材鋼板の板厚を表す。 <Example>
The following steel sheets were prepared as steel sheets to be applied to the butt welding steel sheets for use in the test.
The prepared steel sheet is a steel sheet having a strength class of 1470 MPa after hot stamping, a quadrangle having a side of 10 cm, and a base steel sheet having a plate thickness of 1.6 mm, which is plated with aluminum. The thickness of the aluminum-plated layer and the thickness of the intermetallic compound layer of this steel sheet are as shown in the area column other than the edge portion in Table 2. The chemical composition of the base steel sheet used for each aluminum-plated steel sheet is as shown in Table 1. The plate thickness shown in Table 2 represents the plate thickness of the base steel plate.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　次に、準備した各アルミニウムめっき鋼板において、溶接予定部となる縁部にレーザガウジング処理を施して、突合せ溶接用鋼板とした。具体的には、４辺うちの１辺のみの縁部の両面に対して、１．５ｍｍ幅で、全長１０ｃｍにわたって、レーザガウジング処理を施した。
　一部のアルミニウムめっき鋼板は、レーザガウジングに代えて、レーザアブレーションによる処理を施して、突合せ溶接用鋼板とした。又は一部の鋼板は、溶接予定部となる縁部を未処理として、突合せ溶接用鋼板とした。各突合せ溶接用鋼板の溶接予定部となる縁部におけるアルミニウムめっき層の厚み、及び金属間化合物層の厚みは、表２に示すとおりである。また、式（３）は、母材鋼板の厚みと、片面あたりにおけるアルミニウムめっき層の厚み及び金属間化合物層の厚みから求めた値である。なお、発明例は、両面とも式(３)を満足している。 Next, in each of the prepared aluminum-plated steel sheets, the edge portion to be welded was subjected to laser gouging treatment to obtain a steel sheet for butt welding. Specifically, laser gouging treatment was performed on both sides of the edge portion of only one of the four sides over a width of 1.5 mm and a total length of 10 cm.
Some aluminum-plated steel sheets were treated by laser ablation instead of laser gouging to obtain steel sheets for butt welding. Alternatively, some steel sheets were made into steel sheets for butt welding by leaving the edges to be welded untreated. Table 2 shows the thickness of the aluminum plating layer and the thickness of the intermetallic compound layer at the edge portion of each butt-welding steel sheet to be welded. Further, the formula (3) is a value obtained from the thickness of the base steel plate, the thickness of the aluminum plating layer per one side, and the thickness of the intermetallic compound layer. In addition, the invention example satisfies the formula (3) on both sides.
　次に、各処理を行った突合せ溶接用鋼板（又は未処理の突合せ溶接用鋼板）を２枚用意した。そして、上記の処理をした突合せ溶接用鋼板の縁部の端面を互いに突合せて、レーザ溶接により突合せ溶接を行い、テーラードブランクを作製した。レーザ溶接の条件は、フィラーワイヤを用いず、発振器にはファイバレーザを用い、スポット径φ０．９ｍｍ、レーザ出力３．２ｋＷ、レーザ走査速度３ｍ／ｍｉｎとした。
　次に、作製したテーラードブランクを、９２０℃に加熱した炉で４分間保持後、水冷した金型で成形して、焼入れを行い、平板のホットスタンプ成形品を作製した。これにより、ホットスタンプ成形品は、引張強さ１４７０ＭＰａ級になる。ホットスタンプ成形品の鋼板部において、溶接金属と接続する縁部のアルミニウムめっき層の厚み、金属間化合物層（ＩＭＣ２）の厚み、及びアルミニウムめっき層及び金属間化合物層（ＩＭＣ２）を測定した位置における母材鋼板の板厚ｔ１を表３に示す。 Next, two butt-welded steel sheets (or untreated butt-welded steel sheets) that had been subjected to each treatment were prepared. Then, the end faces of the edges of the butt-welded steel sheets subjected to the above treatment were butted against each other, and butt-welding was performed by laser welding to prepare a tailored blank. The conditions for laser welding were a spot diameter of φ0.9 mm, a laser output of 3.2 kW, and a laser scanning speed of 3 m / min, using a fiber laser as the oscillator without using a filler wire.
Next, the prepared tailored blank was held in a furnace heated to 920 ° C. for 4 minutes, molded with a water-cooled mold, and quenched to prepare a flat plate hot stamped product. As a result, the hot stamped product has a tensile strength of 1470 MPa class. In the steel plate portion of the hot stamped product, the thickness of the aluminum plating layer at the edge connected to the weld metal, the thickness of the intermetallic compound layer (IMC 2 ), and the aluminum plating layer and the intermetallic compound layer (IMC 2 ) were measured. Table 3 shows the plate thickness t 1 of the base steel plate at the position.
　ここで、レーザガウジングの処理条件は以下のとおりである。
　レーザガウジングによる処理として、発振器には半導体レーザを用いた。レーザ照射部後方よりフラットノズルを追従し、窒素を５．５ｋｇｆ／ｃｍ２で噴射した。幅１．５ｍｍ×長さ１ｍｍのラインビームを用いた。レーザ出力０．６ｋＷ～２．１ｋＷ、レーザ走査速度３ｍ／ｍｉｎ～８ｍ／ｍｉｎで適宜調整した。
　Ｎｏ．６を例にすると、レーザ出力０．７ｋＷ、レーザ走査速度５ｍ／ｍｉｎとした。突合せ溶接予定の縁部の表裏それぞれの面を処理した。処理により、Ａｌ－Ｓｉ金属のアルミニウムめっき層が存在せず、金属間化合物層が１７μｍの厚みに成長した。 Here, the processing conditions for laser gouging are as follows.
As a process by laser gouging, a semiconductor laser was used as the oscillator. A flat nozzle was followed from behind the laser irradiation unit, and nitrogen was injected at 5.5 kgf / cm 2 . A line beam having a width of 1.5 mm and a length of 1 mm was used. The laser output was adjusted appropriately at 0.6 kW to 2.1 kW and the laser scanning speed was adjusted at 3 m / min to 8 m / min.
No. Taking No. 6 as an example, the laser output was 0.7 kW and the laser scanning speed was 5 m / min. The front and back surfaces of the edge to be butt welded were treated. By the treatment, the aluminum plating layer of Al—Si metal was not present, and the intermetallic compound layer grew to a thickness of 17 μm.
　また、レーザアブレーションの条件は以下のとおりである。
　レーザアブレーションによる処理として、Ｑスイッチレーザを使用した。処理条件は、パルス幅６０ｎｓ、公称出力３００Ｗ、パルスエネルギー３０ｍＪ、レーザ走査速度１０ｍ／ｍｉｎである。 The conditions for laser ablation are as follows.
A Q-switched laser was used as the process by laser ablation. The processing conditions are a pulse width of 60 ns, a nominal output of 300 W, a pulse energy of 30 mJ, and a laser scanning speed of 10 m / min.
　なお、レーザガウジングと、レーザアブレーションとの違いは、以下のとおりである。
　レーザアブレーションはレーザ光の照射により、固体表面の構成物質が爆発的に放出される現象である。レーザガウジングはレーザ光の照射により、溶融した金属が高速ガスにより除去される現象である。 The differences between laser gouging and laser ablation are as follows.
Laser ablation is a phenomenon in which constituent substances on a solid surface are explosively released by irradiation with laser light. Laser gouging is a phenomenon in which molten metal is removed by high-speed gas by irradiation with laser light.
［評価］
（塗装後耐食性試験）
　上記で得られたホットスタンプ成形品を化成処理した後、電着塗装を行い、塗装後耐食性試験を行った。化成処理は日本パーカライジング（株）製化成処理液ＰＢ－ＳＸ３５Ｔで施した。その後、電着塗料として、日本ペイント（株）製カチオン電着塗料パワーニクス１１０を使用し、電着膜厚約１５μｍを目標として電着塗装を施した。水洗後、１７０℃で２０分間加熱して焼き付け、試験板を作製した。試験板のサイズは６５ｍｍ長さ、１００ｍｍ幅（幅中央部に溶接部がある。）とした。
　この試験板を用いて、自動車部品外観腐食試験ＪＡＳＯ　Ｍ６１０－９２を用い、３６０サイクル（１２０日）経過後の腐食状況で塗装後耐食性を評価した。 [Evaluation]
(Corrosion resistance test after painting)
After the hot stamp molded product obtained above was subjected to chemical conversion treatment, electrodeposition coating was performed, and a corrosion resistance test was conducted after coating. The chemical conversion treatment was carried out with a chemical conversion treatment liquid PB-SX35T manufactured by Nihon Parkerizing Co., Ltd. Then, as the electrodeposition paint, Nippon Paint Co., Ltd.'s cationic electrodeposition paint Powernics 110 was used, and the electrodeposition coating was performed with a target of an electrodeposition film thickness of about 15 μm. After washing with water, it was heated at 170 ° C. for 20 minutes and baked to prepare a test plate. The size of the test plate was 65 mm in length and 100 mm in width (the welded portion is in the center of the width).
Using this test plate, the automobile parts appearance corrosion test JASO M610-92 was used to evaluate the corrosion resistance after painting under the corrosion condition after 360 cycles (120 days).
　塗装後耐食性の評価は、赤錆の割合を赤錆発生率とし、溶接金属周囲を除く領域（突合せ溶接用鋼板の縁部以外の領域に相当）、溶接金属周囲および溶接金属について、目視により下記判定基準で行った。赤錆発生率は少数点以下を四捨五入した値である。溶接金属周囲は評価Ｂまでが許容され、溶接金属は評価Ｂまでが許容される。
－判定基準－
Ａ：赤錆発生率２５％以下
Ｂ：赤錆発生率２６％～５０％
Ｃ：赤錆発生率５１％～７５％
Ｄ：赤錆発生率７６％～１００％ For the evaluation of corrosion resistance after painting, the ratio of red rust is defined as the red rust occurrence rate, and the following criteria are visually observed for the area excluding the periphery of the weld metal (corresponding to the area other than the edge of the butt welding steel plate), the periphery of the weld metal, and the weld metal. I went there. The red rust occurrence rate is a value rounded to the nearest whole number. Up to evaluation B is allowed around the weld metal, and up to evaluation B is allowed for the weld metal.
-Criteria-
A: Red rust occurrence rate 25% or less B: Red rust occurrence rate 26% to 50%
C: Red rust occurrence rate 51% to 75%
D: Red rust occurrence rate 76% to 100%
　なお、表４中において、溶接金属周囲は、以下のことを表す。
　溶接金属周囲は、突合せ溶接用鋼板の縁部にレーザガウジング処理を施した部位のうち、溶接後に形成された溶接金属に隣接し、金属間化合物層の厚みの増加が飽和している領域までの部分を示す。
　レーザアブレーション処理の場合、溶接金属周囲は、溶接金属に隣接し、金属間化合物層が露出している領域までの部分を示す。
　未処理の場合は、レーザガウジング処理における金属間化合物層の厚みの増加が飽和している領域に相当する領域までの部分を示す。 In Table 4, the periphery of the weld metal represents the following.
The periphery of the weld metal is adjacent to the weld metal formed after welding and up to the region where the increase in the thickness of the intermetallic compound layer is saturated among the parts where the edge of the butt-welding steel plate is subjected to laser gouging treatment. Show the part.
In the case of laser ablation treatment, the periphery of the weld metal indicates a portion adjacent to the weld metal and up to the region where the intermetallic compound layer is exposed.
When untreated, the portion up to the region corresponding to the region where the increase in the thickness of the intermetallic compound layer in the laser gouging treatment is saturated is shown.
（引張強度試験）
　得られたホットスタンプ成形品から、引張強度試験用の試験片として、溶接部を持つダンベル状の形状の試験片を採取した。試験片は、平行部距離５０ｍｍ、平行部の幅２５ｍｍとし、平行部の中央部に、長手方向に対して直交方向になるように幅全長にわたって、溶接部を有するように切り出した。この試験片を用いて、静的引張強度試験を実施した。下記判定基準で判定した。評価Ｂまでが許容される。
－判定基準－
Ａ：１４７０ＭＰａ以上
Ｂ：１４００ＭＰａ以上１４７０ＭＰａ未満
Ｃ：１３００ＭＰａ以上１４００ＭＰａ未満
Ｄ：１３００ＭＰａ未満 (Tensile strength test)
From the obtained hot stamped product, a dumbbell-shaped test piece having a welded portion was collected as a test piece for a tensile strength test. The test piece had a parallel portion distance of 50 mm and a width of the parallel portion of 25 mm, and was cut out so as to have a welded portion in the central portion of the parallel portion over the entire width so as to be orthogonal to the longitudinal direction. A static tensile strength test was carried out using this test piece. Judgment was made according to the following criteria. Up to evaluation B is allowed.
-Criteria-
A: 1470 MPa or more B: 1400 MPa or more and less than 1470 MPa C: 1300 MPa or more and less than 1400 MPa D: less than 1300 MPa
（総合判定）
　溶接金属周囲を除く領域の耐食性、溶接金属周囲の耐食性、および溶接金属の耐食性、並びに、静的引張強度の各評価において、もっとも評価の低かった区分を総合判定の判定基準とした。評価Ｂまでが許容される。 (Comprehensive judgment)
In each evaluation of the corrosion resistance in the region other than the periphery of the weld metal, the corrosion resistance around the weld metal, the corrosion resistance of the weld metal, and the static tensile strength, the category with the lowest evaluation was used as the criterion for the comprehensive judgment. Up to evaluation B is allowed.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　表２～表４に示すように、レーザガウジングにより、鋼板の縁部を処理したＮｏ．６、Ｎｏ．７、Ｎｏ．１１、Ｎｏ．１２、Ｎｏ．１４、Ｎｏ．１５、およびＮｏ．１９～Ｎｏ．２２は、金属間化合物層（ＩＭＣ０）の厚みが３ｍｍ～１０ｍｍの範囲を満たしている（つまり、前述の式（２）の範囲を満足している）。また、金属間化合物層（ＩＭＣ１）の厚みが、金属間化合物層（ＩＭＣ０）の厚みよりも大きい（つまり、前述の式（１）の範囲を満足している）。さらに、前述の式（３）の範囲を満足している。そのため、全ての領域（溶接金属周囲以外、溶接金属周囲、及び溶接金属）において、塗装後耐食性及び引張強度が優れていた。そして、これらは、前述の式（４）及び式（５）の範囲を満足している。 As shown in Tables 2 to 4, No. 1 in which the edge of the steel sheet was treated by laser gouging. 6, No. 7, No. 11, No. 12, No. 14, No. 15, and No. 19-No. In No. 22, the thickness of the intermetallic compound layer (IMC 0 ) satisfies the range of 3 mm to 10 mm (that is, the above-mentioned range of the formula (2) is satisfied). The thickness of the intermetallic compound layer (IMC 1) is greater than the thickness of the intermetallic compound layer (IMC 0) (i.e., satisfies the scope of formula (1) above). Further, the range of the above-mentioned equation (3) is satisfied. Therefore, in all regions (around the weld metal, around the weld metal, and the weld metal), the corrosion resistance and the tensile strength after painting were excellent. And these satisfy the range of the above-mentioned equations (4) and (5).
　なお、各図面に付した符号は以下のとおりである。
　１１０　１２０突合せ溶接用鋼板、２２溶接予定部の縁部、２６縁部以外の領域、１２母材鋼板、１６Ａ　１６Ｃ金属間化合物層（ＩＭＣ０）、１６Ｂ　１６Ｄ　１６Ｅ　１６Ｆ　１６Ｇ　１６Ｈ　１６Ｊ金属間化合物層（ＩＭＣ１）、１４Ａ　１４Ｂアルミニウムめっき層、３０溶接金属、２００テーラードブランク、４１０　４２０鋼管 The reference numerals attached to the drawings are as follows.
110 120 Steel plate for butt welding, 22 Edge of planned weld, Area other than 26 edge, 12 base steel plate, 16A 16C intermetallic compound layer (IMC 0 ), 16B 16D 16E 16F 16G 16H 16J intermetallic compound layer ( IMC 1 ), 14A 14B aluminum plating layer, 30 weld metal, 200 tailored blank, 410 420 steel pipe

Claims (7)

  1. 　母材鋼板の両面に、鉄及びアルミニウムを含む金属間化合物層、及びアルミニウムめっき層が当該順で設けられた鋼板であって、
    　前記鋼板の縁部以外の部分における片面あたりのアルミニウムめっき層の厚みをａ０μｍ、及び金属間化合物層（ＩＭＣ０）の厚みをｂ０μｍとし、
    　前記鋼板の縁部の少なくとも一部の部分における片面あたりのアルミニウムめっき層の厚みをａ１μｍ、及び金属間化合物層（ＩＭＣ１）の厚みをｂ１μｍとし、
    　前記縁部以外の部分における母材鋼板の板厚をｔ０μｍとしたとき、
    　下記式（１）、下記式（２）及び下記式（３）を満たす鋼板。
    　式（１）　：　ｂ１（μｍ）＞ｂ０（μｍ）
    　式（２）　：　３μｍ≦ｂ０（μｍ）≦１０μｍ
    　式（３）　：　０．８％≦｛２×（ａ１（μｍ）＋ｂ１（μｍ））／ｔ０（μｍ）｝×１００≦３．５％
    　（ただし、アルミニウムめっき層の厚みａ１は０を含む）     A steel sheet in which an intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided in this order on both sides of the base steel sheet.
    The thickness of the aluminum plating layer per side of the steel sheet other than the edge is a 0 μm, and the thickness of the intermetallic compound layer (IMC 0 ) is b 0 μm.
    The thickness of the aluminum-plated layer per one side of at least a part of the edge of the steel sheet is a 1 μm, and the thickness of the intermetallic compound layer (IMC 1 ) is b 1 μm.
    When the thickness of the base steel plate in the portion other than the edge is t 0 μm,
    A steel sheet that satisfies the following formula (1), the following formula (2), and the following formula (3).
    Equation (1): b 1 (μm)> b 0 (μm)
    Equation (2): 3 μm ≤ b 0 (μm) ≤ 10 μm
    Equation (3): 0.8% ≤ {2 × (a 1 (μm) + b 1 (μm)) / t 0 (μm)} × 100 ≦ 3.5%
    (However, the thickness a 1 of the aluminum plating layer includes 0)
  2. 　前記母材鋼板が、質量％で、
    Ｃ：０．０２％～０．５８％、
    Ｍｎ：０．２０％～３．００％、
    Ａｌ：０．００５％～０．２０％、
    Ｔｉ：０％～０．２０％、
    Ｎｂ：０％～０．２０％、
    Ｖ：０％～１．０％、
    Ｗ：０％～１．０％、
    Ｃｒ：０％～１．０％、
    Ｍｏ：０％～１．０％、
    Ｃｕ：０％～１．０％、
    Ｎｉ：０％～１．０％、
    Ｂ：０％～０．０１００％、
    Ｍｇ：０％～０．０５％、
    Ｃａ：０％～０．０５％、
    ＲＥＭ：０％～０．０５％、
    Ｂｉ：０％～０．０５％、
    Ｓｉ：０％～２．００％、
    Ｐ：０％～０．０３％、
    Ｓ：０％～０．０１０％、
    Ｎ：０％～０．０１０％、並びに
    残部：Ｆｅおよび不純物からなる化学組成を有する請求項１に記載の鋼板。     The base steel sheet is by mass%
    C: 0.02% to 0.58%,
    Mn: 0.20% to 3.00%,
    Al: 0.005% to 0.20%,
    Ti: 0% to 0.20%,
    Nb: 0% to 0.20%,
    V: 0% to 1.0%,
    W: 0% to 1.0%,
    Cr: 0% to 1.0%,
    Mo: 0% to 1.0%,
    Cu: 0% to 1.0%,
    Ni: 0% to 1.0%,
    B: 0% to 0.0100%,
    Mg: 0% to 0.05%,
    Ca: 0% to 0.05%,
    REM: 0% to 0.05%,
    Bi: 0% to 0.05%,
    Si: 0% to 2.00%,
    P: 0% to 0.03%,
    S: 0% to 0.010%,
    The steel sheet according to claim 1, which has a chemical composition consisting of N: 0% to 0.010%, and the balance: Fe and impurities.
  3. 　前記縁部以外の部分での前記アルミニウムめっき層の厚みが８μｍ～５０μｍである請求項１又は請求項２に記載の鋼板。 The steel sheet according to claim 1 or 2, wherein the thickness of the aluminum-plated layer at a portion other than the edge portion is 8 μm to 50 μm.
  4. 　溶接金属と、前記溶接金属に接続する少なくとも２つの鋼板部とを備えるテーラードブランクであって、
    　前記少なくとも２つの鋼板部は、前記溶接金属と接続する縁部、及び前記縁部以外の部分を有し、
    　前記少なくとも２つの鋼板部のうち、少なくとも１つの鋼板部は、前記溶接金属と接続する縁部で、母材鋼板の両面に、少なくとも鉄及びアルミニウムを含む金属間化合物層が設けられており、前記縁部以外の部分で、前記母材鋼板の両面に、鉄及びアルミニウムを含む金属間化合物層、及びアルミニウムめっき層が当該順で設けられており、
    　前記溶接金属と接続する縁部の少なくとも一部の部分における片面あたりのアルミニウムめっき層の厚みをａ１μｍ、及び金属間化合物層（ＩＭＣ１）の厚みをｂ１μｍとし、
    　前記溶接金属と接続する縁部以外の部分における片面あたりのアルミニウムめっき層の厚みをａ０μｍ、及び金属間化合物層（ＩＭＣ０）の厚みをｂ０μｍとし、
    　前記縁部以外の部分における母材鋼板の板厚をｔ０μｍとしたとき、
    　下記式（１）、下記式（２）及び下記式（３）を満たすテーラードブランク。
    　式（１）　：　ｂ１（μｍ）＞ｂ０（μｍ）
    　式（２）　：　３μｍ≦ｂ０（μｍ）≦１０μｍ
    　式（３）　：　０．８％≦｛２×（ａ１（μｍ）＋ｂ１（μｍ））／ｔ０（μｍ）｝×１００≦３．５％
    　（ただし、アルミニウムめっき層の厚みａ１は０を含む）     A tailored blank comprising a weld metal and at least two steel plate portions connected to the weld metal.
    The at least two steel plate portions have an edge portion connected to the weld metal and a portion other than the edge portion.
    Of the at least two steel plate portions, at least one steel plate portion is an edge portion connected to the weld metal, and intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate. An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in a portion other than the edge portion in this order.
    The thickness of the aluminum-plated layer per one surface at least a part of the edge connected to the weld metal is a 1 μm, and the thickness of the intermetallic compound layer (IMC 1 ) is b 1 μm.
    The thickness of the aluminum plating layer per one side in the portion other than the edge portion connected to the weld metal is a 0 μm, and the thickness of the intermetallic compound layer (IMC 0 ) is b 0 μm.
    When the thickness of the base steel plate in the portion other than the edge is t 0 μm,
    A tailored blank that satisfies the following formula (1), the following formula (2), and the following formula (3).
    Equation (1): b 1 (μm)> b 0 (μm)
    Equation (2): 3 μm ≤ b 0 (μm) ≤ 10 μm
    Equation (3): 0.8% ≤ {2 × (a 1 (μm) + b 1 (μm)) / t 0 (μm)} × 100 ≦ 3.5%
    (However, the thickness a 1 of the aluminum plating layer includes 0)
  5. 　溶接金属と、前記溶接金属に接続する少なくとも２つの鋼板部とを備える熱間プレス成形品であって、
    　前記少なくとも２つの鋼板部は、前記溶接金属と接続する縁部、及び前記縁部以外の部分を有し、
    　前記少なくとも２つの鋼板部のうち、少なくとも１つの鋼板部は、前記溶接金属と接続する縁部で、母材鋼板の両面に、少なくとも鉄及びアルミニウムを含む金属間化合物層が設けられており、前記縁部以外の部分で、前記母材鋼板の両面に、鉄及びアルミニウムを含む金属間化合物層、及びアルミニウムめっき層が当該順で設けられており、
    　前記溶接金属と接続する縁部の少なくとも一部の部分における片面あたりのアルミニウムめっき層の厚みをａ２μｍ、及び金属間化合物層（ＩＭＣ２）の厚みをｂ２μｍとし、
    　前記ａ２、及び前記ｂ２の測定位置における母材鋼板の板厚をｔ１μｍとしたとき、
    　下記式（４）及び下記式（５）を満たす熱間プレス成形品。
    　式（４）　：　０．８％≦｛２×（ａ２（μｍ）＋ｂ２（μｍ））／ｔ１（μｍ）｝×１００≦３．５％　
    　式（５）　：１０μｍ≦（ａ２（μｍ）＋ｂ２（μｍ））
    　（ただし、アルミニウムめっき層の厚みａ２は０を含む）     A hot press-formed product comprising a weld metal and at least two steel plate portions connected to the weld metal.
    The at least two steel plate portions have an edge portion connected to the weld metal and a portion other than the edge portion.
    Of the at least two steel plate portions, at least one steel plate portion is an edge portion connected to the weld metal, and intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate. An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in a portion other than the edge portion in this order.
    The thickness of the aluminum plating layer per one side at least a part of the edge connected to the weld metal is a 2 μm, and the thickness of the intermetallic compound layer (IMC 2 ) is b 2 μm.
    When the a 2, and the thickness of the base steel sheet at the measurement position of the b 2 was t 1 [mu] m,
    A hot press molded product that satisfies the following formula (4) and the following formula (5).
    Equation (4): 0.8% ≤ {2 × (a 2 (μm) + b 2 (μm)) / t 1 (μm)} × 100 ≦ 3.5%
    Equation (5): 10 μm ≦ (a 2 (μm) + b 2 (μm))
    (However, the thickness a 2 of the aluminum plating layer includes 0)
  6. 　溶接金属と、周方向の２つの縁部が互いに対向するオープン管状に形成され、前記溶接金属に、前記周方向の２つの縁部が接続する鋼板部とを備える鋼管であって、
    　前記鋼板部は、少なくとも１つの鋼板部を有し、前記少なくとも１つの鋼板部は、前記溶接金属と接続する縁部、及び前記縁部以外の部分を有し、
    　前記少なくとも１つの鋼板部は、前記溶接金属と接続する縁部で、母材鋼板の両面に、少なくとも鉄及びアルミニウムを含む金属間化合物層が設けられており、前記縁部以外の部分で、前記母材鋼板の両面に、鉄及びアルミニウムを含む金属間化合物層、及びアルミニウムめっき層が当該順で設けられており、
    　前記溶接金属と接続する縁部の少なくとも一部の部分における片面あたりのアルミニウムめっき層の厚みをａ１μｍ、及び金属間化合物層（ＩＭＣ１）の厚みをｂ１μｍとし、
    　前記溶接金属と接続する縁部以外の部分における片面あたりのアルミニウムめっき層の厚みをａ０μｍ、及び金属間化合物層（ＩＭＣ０）の厚みをｂ０μｍとし、
    　前記縁部以外の部分における母材鋼板の板厚をｔ０μｍとしたとき、
    　下記式（１）、下記式（２）及び下記式（３）を満たす鋼管。
    　式（１）　：　ｂ１（μｍ）＞ｂ０（μｍ）
    　式（２）　：　３μｍ≦ｂ０（μｍ）≦１０μｍ
    　式（３）　：　０．８％≦｛２×（ａ１（μｍ）＋ｂ１（μｍ））／ｔ０（μｍ）｝×１００≦３．５％
    　（ただし、アルミニウムめっき層の厚みａ１は０を含む）     A steel pipe comprising a weld metal and a steel plate portion in which two peripheral edges are formed in an open tubular shape facing each other and the weld metal is connected to the two peripheral edges.
    The steel plate portion has at least one steel plate portion, and the at least one steel plate portion has an edge portion connected to the weld metal and a portion other than the edge portion.
    The at least one steel plate portion is an edge portion connected to the weld metal, and intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate, and the portion other than the edge portion is the said. An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order.
    The thickness of the aluminum-plated layer per one surface at least a part of the edge connected to the weld metal is a 1 μm, and the thickness of the intermetallic compound layer (IMC 1 ) is b 1 μm.
    The thickness of the aluminum plating layer per one side in the portion other than the edge portion connected to the weld metal is a 0 μm, and the thickness of the intermetallic compound layer (IMC 0 ) is b 0 μm.
    When the thickness of the base steel plate in the portion other than the edge is t 0 μm,
    A steel pipe that satisfies the following formula (1), the following formula (2), and the following formula (3).
    Equation (1): b 1 (μm)> b 0 (μm)
    Equation (2): 3 μm ≤ b 0 (μm) ≤ 10 μm
    Equation (3): 0.8% ≤ {2 × (a 1 (μm) + b 1 (μm)) / t 0 (μm)} × 100 ≦ 3.5%
    (However, the thickness a 1 of the aluminum plating layer includes 0)
  7. 　溶接金属と、周方向の２つの縁部が互いに対向するオープン管状に形成され、前記溶接金属に、前記周方向の２つの縁部が接続する鋼板部とを備える中空状焼入れ成形品であって、
    　前記鋼板部は、少なくとも１つの鋼板部を有し、前記少なくとも１つの鋼板部は、前記溶接金属と接続する縁部、及び前記縁部以外の部分を有し、
    　前記少なくとも１つの鋼板部は、前記溶接金属と接続する縁部で、母材鋼板の両面に、少なくとも鉄及びアルミニウムを含む金属間化合物層が設けられており、前記縁部以外の部分で、前記母材鋼板の両面に、鉄及びアルミニウムを含む金属間化合物層、及びアルミニウムめっき層が当該順で設けられており、
    　前記溶接金属と接続する縁部の少なくとも一部の部分における片面あたりのアルミニウムめっき層の厚みをａ２μｍ、及び金属間化合物層（ＩＭＣ２）の厚みをｂ２μｍとし、
    　前記ａ２、及び前記ｂ２の測定位置における母材鋼板の板厚をｔ１μｍとしたとき、
    　下記式（４）及び下記式（５）を満たす熱間プレス成形品。
    　式（４）　：　０．８％≦｛２×（ａ２（μｍ）＋ｂ２（μｍ））／ｔ１（μｍ）｝×１００≦３．５％　
    　式（５）　：１０μｍ≦（ａ２（μｍ）＋ｂ２（μｍ））
    　（ただし、アルミニウムめっき層の厚みａ２は０を含む）     A hollow hardened molded product in which a weld metal and two peripheral edges are formed in an open tubular shape facing each other, and the weld metal is provided with a steel plate portion to which the two peripheral edges are connected. ,
    The steel plate portion has at least one steel plate portion, and the at least one steel plate portion has an edge portion connected to the weld metal and a portion other than the edge portion.
    The at least one steel plate portion is an edge portion connected to the weld metal, and intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate, and the portion other than the edge portion is the said. An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order.
    The thickness of the aluminum plating layer per one side at least a part of the edge connected to the weld metal is a 2 μm, and the thickness of the intermetallic compound layer (IMC 2 ) is b 2 μm.
    When the a 2, and the thickness of the base steel sheet at the measurement position of the b 2 was t 1 [mu] m,
    A hot press molded product that satisfies the following formula (4) and the following formula (5).
    Equation (4): 0.8% ≤ {2 × (a 2 (μm) + b 2 (μm)) / t 1 (μm)} × 100 ≦ 3.5%
    Equation (5): 10 μm ≦ (a 2 (μm) + b 2 (μm))
    (However, the thickness a 2 of the aluminum plating layer includes 0)
PCT/JP2019/014687 2019-04-02 2019-04-02 Steel sheet, tailored blank, hot-pressed molded product, steel pipe, and hollow quenched molded product WO2020202474A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009534529A (en) * 2006-04-19 2009-09-24 アルセロールミタル・フランス Method for producing welded parts with very high mechanical properties from coated laminates
JP2017514694A (en) * 2014-04-25 2017-06-08 アルセロールミタル Method for producing an aluminized steel sheet which is welded and then press hardened
JP2017518438A (en) * 2014-03-31 2017-07-06 アルセロールミタル Press quenching and coated steel parts manufacturing method with high production rate
WO2018096387A1 (en) * 2016-11-24 2018-05-31 Arcelormittal Hot-rolled and coated steel sheet for hot-stamping, hot-stamped coated steel part and methods for manufacturing the same

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009534529A (en) * 2006-04-19 2009-09-24 アルセロールミタル・フランス Method for producing welded parts with very high mechanical properties from coated laminates
JP2017518438A (en) * 2014-03-31 2017-07-06 アルセロールミタル Press quenching and coated steel parts manufacturing method with high production rate
JP2017514694A (en) * 2014-04-25 2017-06-08 アルセロールミタル Method for producing an aluminized steel sheet which is welded and then press hardened
WO2018096387A1 (en) * 2016-11-24 2018-05-31 Arcelormittal Hot-rolled and coated steel sheet for hot-stamping, hot-stamped coated steel part and methods for manufacturing the same

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