WO2014178303A1 - Flat steel wire - Google Patents
Flat steel wire Download PDFInfo
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- WO2014178303A1 WO2014178303A1 PCT/JP2014/061228 JP2014061228W WO2014178303A1 WO 2014178303 A1 WO2014178303 A1 WO 2014178303A1 JP 2014061228 W JP2014061228 W JP 2014061228W WO 2014178303 A1 WO2014178303 A1 WO 2014178303A1
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- 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
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
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- 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
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/525—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length for wire, for rods
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- 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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- 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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- 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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- 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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- 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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- 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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- 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
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
-
- 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
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
-
- 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
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- 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
- C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
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- 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
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
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- 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
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
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- 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
- C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
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- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B1/00—Constructional features of ropes or cables
- D07B1/06—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core
- D07B1/0606—Reinforcing cords for rubber or plastic articles
- D07B1/066—Reinforcing cords for rubber or plastic articles the wires being made from special alloy or special steel composition
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- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
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- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B2201/00—Ropes or cables
- D07B2201/20—Rope or cable components
- D07B2201/2001—Wires or filaments
- D07B2201/2002—Wires or filaments characterised by their cross-sectional shape
- D07B2201/2003—Wires or filaments characterised by their cross-sectional shape flat
Definitions
- the present invention relates to a high-strength flat steel wire excellent in secondary workability and used for improving pressure resistance and tension of power / communication wires, pipes / hoses and the like.
- Patent Document 1 discloses a high-strength flat steel wire containing 0.90% by mass or more of carbon.
- This flat steel wire is a high-strength flat steel wire having a tensile strength in the longitudinal direction of about 200 kgf / mm 2 .
- the secondary workability of a flat steel wire decreases as the strength of the flat steel wire increases. Even if the strength of the conventional flat steel wire is excellent, it has already reached the processing limit and is often difficult to be subjected to secondary processing such as bending and twisting.
- flat steel wires are often used for reinforcing flexible pipes.
- high pressure resistance and tension are required for a flexible pipe used when pulling crude oil from a deep-sea oil field. Therefore, the flat steel wire is required to have high strength.
- the flat steel wire is used by being deformed into a spiral shape with respect to the flexible pipe. Therefore, flat steel wires are required to have excellent secondary workability with respect to twisting and the like.
- a flat steel wire with poor secondary workability when it is deformed into a spiral shape, cracks may enter from the outer periphery and may be broken into vertical cracks. That is, when the flat steel wire is excellent in strength and secondary workability, a flexible pipe having high pressure resistance and tension can be realized.
- An object of the present invention is to provide a high-strength flat steel wire excellent in secondary workability.
- the strength means tensile yield strength, 0.2% proof stress in a tensile test, maximum tensile strength, and the like, and the secondary workability means twisting property, tensile elongation at break, and the like.
- the gist of the present invention is as follows.
- a flat steel wire according to an aspect of the present invention is a flat steel wire that is a rounded rectangle when viewed in a cross section perpendicular to the longitudinal direction, and a short side of the cross section is 2 mm or more and 7 mm or less,
- the long side of the cross section is 8 mm to 56 mm or less, the ratio of the long side to the short side is 4 to 8 or less, the yield strength or 0.2% yield strength obtained by a tensile test is 1600 MPa to 2000 MPa, and the tensile strength is 1900 MPa.
- the elongation at break is 2% or more
- the twist value obtained by the twist test under the condition that the distance between chucks is 500 mm is 12 times or more.
- an average value of the compressive residual stress in the longitudinal direction may be ⁇ 200 MPa or less in the surface layer portion.
- the chemical component is mass%, C: 0.85% to 1.00%, Si: 0.80% to 1.30. %: Mn: 0.30% or more and 0.90% or less, P: 0.017% or less, S: 0.010% or less, Cu: 0.20% or less, Al: 0% or more and 0.10% or less Ti: 0% or more and 0.05% or less, B: 0% or more and 0.0040% or less, N: 0% or more and 0.0060% or less, Cr: 0% or more and 0.5% or less, V: 0% or more It may contain 0.50% or less, and the balance may consist of Fe and impurities.
- the chemical component is, by mass%, Al: 0.005% or more and 0.10% or less, Ti: 0.00. It may contain at least one of 003% or more and 0.05% or less, B: 0.0005% or more and 0.0040% or less, and N: 0.0015% or more and 0.0060% or less.
- the chemical component is, by mass, Cr: 0.1% to 0.5%, V: 0.00. You may contain at least 1 of 005% or more and 0.50% or less.
- the short side of the cross section is 2 mm to 6 mm, and the long side of the cross section is more than 8 mm and 48 mm or less. Also good.
- the short side of the cross section may be 2 mm or more and 5 mm or less, and the long side of the cross section may be more than 8 mm and 40 mm or less.
- the shape of the flat steel wire and the like is preferably controlled, for example, during the twisting process, the occurrence of cracks from the outer peripheral surface of the flat steel wire and the vertical crack of the flat steel wire due to its progress Etc. are suppressed. As a result, it is possible to obtain a high-strength flat steel wire having high secondary workability as compared with conventional high-strength flat steel wires.
- the inventors of the present invention have a rounded rectangular shape when viewed in a cross section perpendicular to the longitudinal direction, and the ratio of the long side of the cross section to the short side of the cross section (long side / short side) is more than 4 and less than 8 It was found that the twisting characteristics of the flat steel wire can be improved by restricting to. It is considered that the twisting characteristics are improved by suppressing cracks from the outer peripheral surface of the flat steel wire, particularly corners, and suppressing non-uniform deformation.
- the twisting characteristics of a flat steel wire are preferably improved by controlling the residual stress of the surface portion of the flat steel wire to a compressive stress state. Since the region where the residual stress of the surface layer portion of the flat steel wire is in the tensile stress state is likely to be a starting point of fracture, it is considered that the twisting characteristics are preferably improved by reducing the region that becomes the tensile residual stress in the surface layer portion.
- the twisting characteristic of the flat steel wire is further increased. It has been found that it is preferably improved.
- the C content By controlling the C content, a uniform and fine pearlite structure is formed even under heat treatment conditions that can be applied industrially, and thus it is considered that the twisting characteristics are more preferably improved.
- fixing N in the steel suppresses the age hardening of the flat steel wire, thereby suppressing local hardening in the flat steel wire and the accompanying non-uniform deformation, further increasing the twisting characteristics. It is thought that it improves preferably.
- the flat steel wire according to the present embodiment has a high strength of a tensile yield strength or 0.2% proof stress of 1600 MPa or more and a maximum tensile strength (tensile strength) of 1900 MPa or more, and at the same time a tensile breaking elongation of 2% or more. Also, it has excellent secondary workability such that the twist value in the twist test is 12 times or more.
- structural steel is regarded as high-strength steel when the tensile strength is 1000 MPa or more.
- the twist value is 12 times or more, it is considered that the twist characteristics are excellent. That is, it can be said that the flat steel wire according to the present embodiment simultaneously satisfies two contradictory properties of strength and secondary workability.
- a flexible pipe having high pressure resistance and tension can be realized.
- the flat steel wire according to the present embodiment has a rounded rectangular shape when viewed in a cross section perpendicular to the longitudinal direction, the short side of the cross section is 2 mm or more and 7 mm or less, and the long side of the cross section is more than 8 mm and 56 mm.
- the ratio of the long side to the short side is more than 4 and 8 or less.
- the shorter dimension (short side) is referred to as “thickness” and the longer dimension (long side) is referred to as “width”.
- the shorter side of the cross section that is a rounded rectangle is defined as the short side (thickness).
- the length of the short side is defined as the length from the corner to the corner when the corner of the cross section is assumed to be a substantially right angle without roundness.
- the longer side of the cross section that is a rounded rectangle is defined as the long side (width).
- the length of the long side is defined as the length from the corner to the corner when the corner of the cross section is assumed to be a substantially right angle without roundness.
- the short side (thickness) and the long side (width) in the said cross section of the flat steel wire 1 which concern on this embodiment are shown typically.
- the flat steel wire 1 has a rectangular shape when viewed in a cross section perpendicular to the longitudinal direction, and each corner portion has an arc shape. That is, the cross-sectional shape is a rounded rectangle with rounded corners. Since the cross-sectional shape is a rounded rectangle, the breakage starting from the corner is suppressed during the secondary processing. Moreover, when the cross-sectional shape is a rounded rectangular shape, when the flat steel wire 1 is deformed in a spiral shape with respect to the pipe, interference between corner portions of the adjacent flat steel wires 1 is suppressed.
- the thickness of the flat steel wire 1 is The upper limit is 7 mm. Moreover, in order to perform a twisting process stably, the thickness of the flat steel wire 1 needs to be 2 mm or more. That is, the thickness of the flat steel wire 1 according to this embodiment is 2 mm or more and 7 mm or less.
- the present inventors need to make the width / thickness ratio (ratio of long side to short side) more than 4 and 8 or less. I found. When the ratio of the long side to the short side is 8 or less, the non-uniform deformation is suppressed, so that the twisting characteristic is considered to be improved. Further, if the ratio of the long side to the short side is 4 or less, it is necessary to contain carbon and alloy elements more than necessary for securing the strength. As a result, the ductility and secondary workability of the flat steel wire 1 are improved. Reduce.
- the width (long side) of the flat steel wire 1 is 8 mm. What is necessary is just to be super 56 mm or less.
- the short side of a cross section is 2 mm or more and 6 mm or less, and the long side of a cross section is 8 mm over 48 mm or less. More preferably, the short side of the cross section is 2 mm or more and 5 mm or less, and the long side of the cross section is more than 8 mm and 40 mm or less.
- the minimum of width / thickness ratio is 5 or more, and it is preferable that the upper limit of width / thickness ratio is 7 or less.
- the flat steel wire 1 according to the present embodiment has a tensile strength of 1900 MPa or more.
- the upper limit of the tensile strength is not particularly limited, but may be 2400 MPa.
- the elongation at break is set to 2% or more in order to ensure ductility.
- the upper limit of the elongation at break is not particularly limited, but may be 5%.
- yield strength or 0.2% yield strength shall be 1600 Mpa or more.
- the upper limit of the yield strength or 0.2% proof stress is not particularly limited, but may be 2000 MPa.
- yield strength or 0.2% yield strength is a value lower than tensile strength.
- the ratio of yield strength or 0.2% yield strength to tensile strength is preferably 0.8 or more and 0.95 or less.
- the above-described mechanical characteristics may be controlled according to manufacturing conditions such as rolling conditions.
- the above-described mechanical characteristics may be controlled by controlling the wire diameter of the steel wire before rolling and the rolling temperature and rolling reduction during rolling.
- you may control an above-described mechanical characteristic by controlling the chemical component of the flat steel wire 1 as needed.
- the flat steel wire 1 according to this embodiment has excellent secondary workability because the shape of the flat steel wire 1 and the like are preferably controlled. Specifically, in a twist test under the condition that the distance between chucks is set to 500 mm, a twist process of 12 times or more can be performed. Thus, in the flat steel wire 1 which concerns on this embodiment, intensity
- FIG. 2 shows a flat steel wire 1 according to this embodiment after twisting. As shown in FIG. 2, it is confirmed that the flat steel wire 1 according to the present embodiment has excellent twist characteristics despite high strength.
- the upper limit of the twist value is not particularly limited, but may be 25 times.
- the residual stress means a tensile residual stress when the value is positive, and a compressive residual stress when the value is negative.
- the twist characteristic of the flat steel wire 1 is preferably improved by controlling the average value of the residual stress of the surface layer portion 2 of the flat steel wire 1 to a compressive stress state.
- the surface layer portion 2 of the flat steel wire 1 when a region whose depth is within 1 ⁇ m from the contour line of the cross section toward the center of gravity of the cross section when viewed in a cross section perpendicular to the longitudinal direction is the surface layer portion 2 of the flat steel wire 1, In the surface layer portion 2, the average value of the residual stress in the longitudinal direction may be ⁇ 200 MPa or less.
- the twisting characteristics of the flat steel wire 1 are preferably improved.
- the average value of residual stress being ⁇ 200 MPa or less means that the average value of residual stress is ⁇ 220 MPa or ⁇ 250 MPa, for example.
- the lower limit of the average value of the residual stress is not particularly limited, but may be ⁇ 1200 MPa. That is, the average value of residual stress is preferably ⁇ 1200 MPa or more and ⁇ 200 MPa or less.
- the residual stress of the surface layer portion 2 of the flat steel wire 1 is, as an average, a compressive stress state, and its value When the value is ⁇ 200 MPa or less, the above effect can be preferably obtained.
- FIG. 1 schematically shows the surface layer portion 2 when viewed in a cross section perpendicular to the longitudinal direction.
- FIG. 3 shows the relationship between the average value of the residual stress of the surface layer portion 2 and the twist value in the twist test.
- FIG. 3 shows that the twisting characteristics of the flat steel wire 1 are critically improved when the average value of the compressive residual stress of the surface layer portion 2 is ⁇ 200 MPa or less.
- the region where the residual stress of the surface layer portion 2 of the flat steel wire 1 is in a tensile stress state is likely to be a starting point of fracture, it is preferable to control the surface layer portion 2 to a compressive residual stress having an average value of ⁇ 200 MPa or less.
- a compressive stress state it is preferable to perform shot blasting or the like.
- the average value of the compressive residual stress in the surface layer part 2 is more preferably ⁇ 300 MPa or less or ⁇ 400 MPa or less.
- the surface layer portion 2 of the flat steel wire 1 is more preferably a region whose depth is within 2 ⁇ m or within 3 ⁇ m toward the center of gravity.
- the chemical composition of the flat steel wire 1 according to the present embodiment is mass%, C: 0.85% to 1.00%, Si: 0.80% to 1.30%, Mn: 0.30% 0.90% or less, P: 0.017% or less, S: 0.010% or less, Cu: 0.20% or less, Al: 0% or more and 0.10% or less, Ti: 0% or more and 0.05 %: B: 0% to 0.0040%, N: 0% to 0.0060%, Cr: 0% to 0.5%, V: 0% to 0.50%, the balance Is preferably composed of Fe and impurities.
- C, Si, and Mn are basic elements.
- C 0.85% or more and 1.00% or less
- C (carbon) is an element that improves the strength of pearlite steel by increasing the cementite fraction of pearlite steel.
- the C content is 0.85% or more because the tensile strength can be 1900 MPa or more while ensuring ductility. Therefore, the lower limit of the C content may be 0.85%.
- the upper limit of the C content may be 1.00%.
- Si 0.80% or more and 1.30% or less
- Si is a deoxidizing element at the time of refining steel, and is an element that solidifies and strengthens ferrite.
- the lower limit of the Si content may be 0.80%.
- the nose temperature of the isothermal transformation at the time of heat processing can be controlled preferably. Therefore, the upper limit of the Si content may be 1.30%.
- Mn 0.30% or more and 0.90% or less
- Mn manganese
- the lower limit of the Mn content may be 0.30%.
- the upper limit of the Mn content may be 0.90%.
- the flat steel wire 1 contains impurities as chemical components.
- the “impurity” refers to a material mixed from ore as a raw material, scrap, or a production environment when steel is industrially produced.
- P, S, and Cu are preferably limited as follows in order to sufficiently exhibit the above effects.
- limit a lower limit and the lower limit of an impurity may be 0%.
- P 0.017% or less
- P (phosphorus) is an impurity.
- the P content is 0.017% or less, it is preferable because the embrittlement of the steel can be suppressed and cracking during processing of the flat steel wire 1 can be suppressed. Therefore, the P content may be limited to 0.017% or less.
- S 0.010% or less
- S (sulfur) is an impurity.
- S combines with Mn in steel to form MnS.
- S segregates at the center of the steel slab during the refining-solidification process of the steel, and a large amount of MnS is formed at this center to embrittle the steel.
- S content is 0.010% or less, since the fracture
- Cu 0.20% or less
- Cu (copper) is an impurity mainly mixed from scrap or the like.
- Cu also has an effect of hardening steel by solid solution strengthening.
- the Cu content is 0.20% or less, the workability of the flat steel wire 1 can be remarkably reduced, which is preferable. Therefore, the Cu content may be limited to 0.20% or less.
- the chemical components of the flat steel wire 1 according to the present embodiment contain the basic elements and the balance Fe and impurities.
- the flat steel wire 1 according to the present embodiment may contain Al, Ti, B, N, Cr, and V as selective elements instead of a part of Fe that is the balance. These selective elements may be contained depending on the purpose. Therefore, it is not necessary to limit the lower limit values of these selected elements, and the lower limit value may be 0%. Moreover, even if these selective elements are contained as impurities, the above effects are not impaired.
- Al 0% or more and 0.10% or less
- Al (aluminum) is a deoxidizing element when refining steel, and is an element that forms a compound by combining with N in steel.
- the age hardening of the flat steel wire 1 is suppressed by Al fixing N in the steel.
- Al increases the amount of solute B in steel by fixing N in steel. Therefore, if necessary, the Al content may be 0% or more and 0.10% or less.
- the lower limit of the preferable Al content is 0.005%. Further, when the Al content is less 0.10%, since the cracking during processing due to the Al 2 O 3 to form a cluster can be suppressed preferred.
- Ti 0% or more and 0.05% or less
- Ti titanium
- Ti titanium
- Ti titanium
- the Ti content may be 0% or more and 0.05% or less as necessary.
- the lower limit of the preferable Ti content is 0.003%.
- Ti content is 0.05% or less, since the crack at the time of the process resulting from TiC increasing can be suppressed, it is preferable.
- B 0% or more and 0.0040% or less
- B (boron) is an element that dissolves in austenite and improves hardenability. Therefore, the B content may be 0% or more and 0.0040% or less as necessary. The lower limit of the preferable B content is 0.0005%. Also, when the B content is less 0.0040%, Fe 23 (C, B) since the cracking during processing due to precipitation of such 6 can be suppressed preferred.
- N 0% or more and 0.0060% or less
- N nitrogen
- the N content may be 0% or more and 0.0060% or less as necessary.
- the lower limit of the preferable N content is 0.0015%. Further, when the N content is 0.0060% or less, age hardening due to excessive free N that does not bond with Al, Ti, B is suppressed, and as a result, the ductility reduction of the flat steel wire 1 is suppressed. preferable.
- Cr 0% or more and 0.5% or less
- Cr is an element that reduces the lamella spacing of pearlite and improves the strength of pearlite steel. Cr is an element that contributes to an increase in strength during wire drawing. Therefore, the Cr content may be 0% or more and 0.5% or less as necessary. The lower limit of the preferable Cr content is 0.1%. Moreover, when Cr content is 0.5% or less, since the fall of productivity resulting from pearlite transformation completion time becoming long can be suppressed, it is preferable.
- V 0% or more and 0.50% or less
- V (Vanadium) is an element that combines with C in steel to precipitate carbide in ferrite. This precipitate hardens the ferrite. Therefore, the V content may be 0% or more and 0.5% or less as necessary. The lower limit of the preferred V content is 0.005%. Moreover, when V content is 0.50% or less, since the crack at the time of the process resulting from the production
- the flat steel wire 1 may have a plating layer or a coating layer on the surface.
- a plating layer or a coating layer on the surface.
- the flat steel wire 1 according to this embodiment may have a Zn or Ni-containing plating layer having a thickness of 10 ⁇ m or less on the surface.
- This plating layer is preferable because corrosion of the flat steel wire 1 can be suppressed, and delayed fracture due to hydrogen intrusion due to corrosion or hydrogen intrusion from the environment can be suppressed.
- the thickness of a plating layer is 10 micrometers or less, since peeling of the plating layer at the time of secondary processing can be suppressed, it is preferable.
- the flat steel wire 1 according to the present embodiment may have a coating layer of a resin or the like having an anticorrosive effect on the surface. The effect similar to a plating layer is acquired by this coating layer.
- the tensile properties of the flat steel wire 1 according to the present embodiment may be obtained by a tensile test based on JIS Z2241: 2011 or ISO 6892-1: 2009. From the tensile test results, yield strength or 0.2% proof stress, maximum tensile strength (tensile strength), and elongation at break are determined.
- the twist characteristics of the flat steel wire 1 according to the present embodiment may be obtained by a twist test in which one end is rotated after chucking both ends with a flat blade chuck. At that time, the flat steel wire 1 is twisted under the conditions that the distance between chucks is 500 mm, the twisting speed is 10 rpm, and the test temperature is room temperature. The number of twists until disconnection is defined is defined as the twist value.
- the residual stress of the surface layer portion 2 of the flat steel wire 1 may be obtained by X-ray diffraction. It is possible to obtain the residual stress in the longitudinal direction of the surface layer portion 2 of the flat steel wire 1 by performing X-ray diffraction using a plane parallel to the longitudinal direction of the flat steel wire 1 and analyzing the X-ray diffraction result. it can. In addition, what is necessary is just to measure the residual stress of the surface layer part 2 in multiple places, and to calculate the average value of a residual stress from these measurement results.
- the long side (width) of the flat steel wire 1 is divided into four equal parts, and three points excluding both sides of the equally divided points are used as measurement points, and the short side (thickness) is divided into three equal parts.
- the equally divided points two points excluding both sides are preferably used as measurement points.
- the surface layer portion 2 of the flat steel wire 1 is defined as a region having a depth of 1 ⁇ m or less from the contour line of the cross section toward the center of gravity of the cross section.
- the target uses Cr to determine the diffraction angle.
- the relationship between the angle ⁇ formed by the sample surface normal and the crystal surface normal and the X-ray diffraction angle ⁇ is plotted, and the residual stress is obtained from the slope of the approximate straight line.
- the manufacturing method of the flat steel wire 1 according to the present embodiment is not particularly limited.
- the flat steel wire 1 according to the present embodiment may be manufactured by a steel making process, a casting process, a wire rod rolling process, a constant temperature transformation process, a wire drawing process, and the like.
- you may have a shot blast process and a surface treatment process after a wire-drawing process as needed.
- the steelmaking process it is preferable to make steel in order to obtain molten steel composed of the basic elements, selective elements, and impurities described above.
- the steelmaking method is not particularly limited, the molten steel may be produced by a blast furnace method using ore or the like as a raw material and an electric furnace method using scrap or the like as a raw material.
- steelmaking conditions may be that ⁇ T (degree of superheat) is 15 to 20 ° C. By the said conditions, the center segregation of the flat steel wire 1 can be controlled preferably.
- the casting process it is preferable to cast the molten steel after the steel making process in order to obtain a slab.
- the casting method is not particularly limited, but a vacuum casting method, a continuous casting method, or the like may be used.
- the central segregation of the flat steel wire 1 can be preferably controlled by suppressing concentrated segregated molten steel suction during solidification shrinkage by appropriate reduction of the crater end.
- the wire rod rolling step it is preferable to roll the slab after the casting step in order to obtain a wire rod.
- the wire rolling conditions are not particularly limited.
- the wire rolling start temperature is set in a temperature range of 1050 ° C. or higher and 1150 ° C. or lower
- the wire rolling end temperature is set in a temperature range of 900 ° C. or higher and 1050 ° C. or lower
- accumulation in wire rolling is performed.
- the rolling reduction may be in the range of 98.7% to 99.8%.
- the center segregation of the flat steel wire 1 can be controlled preferably.
- the wire after the wire rolling step it is preferable to keep the wire after the wire rolling step at a constant temperature transformation temperature and to cool the wire to room temperature after the constant temperature transformation treatment.
- the wire rod after the wire rod rolling process may be directly subjected to the isothermal transformation treatment without cooling to room temperature, or the wire rod after the wire rod rolling step is cooled to room temperature and then reheated to perform the isothermal transformation treatment.
- the isothermal transformation condition is not particularly limited, but for example, the wire may be immersed in a molten salt maintained in a temperature range of 530 ° C. or higher and 550 ° C. or lower for a time of 60 seconds or longer and 90 seconds or shorter.
- the flat steel wire 1 mainly includes a pearlite structure as a metal structure.
- finish temperature to a constant temperature transformation temperature is set to the cooling rate of 12 to 30 degree C / sec.
- the wire may be cooled.
- the wire after the isothermal transformation is drawn.
- the short side of the cross section is 2 mm or more and 7 mm or less
- the long side of the cross section is more than 8 mm and 56 mm or less
- the ratio of the long side to the short side is The wire after the isothermal transformation is drawn into a flat steel wire 1 so that becomes more than 4 and 8 or less.
- the wire drawing method is not particularly limited, for example, wire drawing by a wire drawing die and flat rolling may be combined. Specifically, after drawing the wire after constant temperature transformation with a normal wire drawing die, wire drawing with a round cross-section die or a rectangular cross-section die and flat rolling may be combined as necessary.
- the strength of the flat steel wire 1 according to this embodiment increases as the processing amount in the wire drawing process increases.
- the cross-sectional reduction rate in the wire drawing step is 50% or more and 90% or less.
- the shot blasting conditions are not particularly limited.
- an inorganic abrasive is used as shot blast particles
- the shot blast particle size is set to 340 ⁇ m or more and 400 ⁇ m or less
- the shot blast pressure is set to 1 kg / cm 2 or more and 3 kg / cm 2 or less
- the blast time may be 10 seconds or more and 20 seconds or less.
- the shot blast particle size may be 370 ⁇ m
- the shot blast pressure may be 2 kg / cm 2
- the shot blast time may be 15 seconds.
- the above conditions are preferable because the average value of the compressive residual stress in the longitudinal direction of the surface layer portion 2 of the flat steel wire 1 can be controlled to be ⁇ 200 MPa or less.
- the flat steel wire 1 after the wire drawing step or the shot blasting step may be subjected to surface treatment. It is preferable to apply a plating layer or a coating layer to the flat steel wire 1 by surface treatment.
- the surface treatment conditions are not particularly limited, and general plating treatment or surface coating treatment may be performed.
- Example Invention Example Nos. Shown in Tables 1 to 4 1 to 18 and Comparative Example No. 19 to 30 flat steel wires were produced.
- the metal structure of the flat steel wire was adjusted to a fine pearlite structure in the constant temperature transformation process after the wire rod rolling process. Further, in order to increase the strength, in the wire drawing step, the wire was drawn halfway with a normal wire drawing die, and then formed by performing at least one of wire drawing using a round cross-section die or a rectangular cross-section die and flat rolling. Moreover, if necessary, shot blasting was performed on a flat steel wire as a shot blasting process.
- An inorganic abrasive is used as the shot blast grain, the shot blast particle size is 340 ⁇ m or more and 400 ⁇ m or less, the shot blast pressure is 1 kg / cm 2 or more and 3 kg / cm 2 or less, and the shot blasting time is 10 seconds or more and 20 seconds or less. Then, shot blasting was applied to the flat steel wire.
- Tensile properties were measured by performing a tensile test based on JIS Z2241: 2011 or ISO 6892-1: 2009. From the tensile test results, yield strength or 0.2% yield strength, tensile maximum strength (tensile strength), and elongation at break were determined.
- the twisting property was measured by performing a twisting test in which one side was rotated after chucking both ends with a flat blade chuck. At that time, the flat steel wire was twisted under the conditions that the distance between chucks was 500 mm, the twisting speed was 10 rpm, and the test temperature was room temperature. Then, the number of twists until disconnection and separation was taken as the twist value.
- Residual stress was determined by analyzing the X-ray diffraction results for the surface layer portion of the flat steel wire. Specifically, the long side (width) of the flat steel wire is divided into four equal parts, and the three points excluding both sides of the equally divided points are used as measurement points, and the short side (thickness) is divided into three equal parts, Two points of the equally divided points excluding both sides were taken as measurement points. The measurement points were determined by the same method for each opposite side, and X-ray diffraction was performed at a total of 10 measurement points. By analyzing these X-ray diffraction results, the average value of the residual stress in the longitudinal direction perpendicular to the cut surface was determined. Using Cr as a target, the relationship between the angle ⁇ formed by the sample surface normal and the crystal surface normal and the X-ray diffraction angle ⁇ was plotted, and the residual stress was obtained from the slope of the approximate straight line.
- the shape of the flat steel wire and the like is preferably controlled, for example, during the twisting process, the occurrence of cracks from the outer peripheral surface of the flat steel wire and the vertical crack of the flat steel wire due to its progress Etc. are suppressed.
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Abstract
A flat steel wire has a rounded rectangular cross section when the cross section is taken in a direction perpendicular to the length direction, wherein the length of the shorter side of the cross section is 2 to 7 mm inclusive, the length of the longer side of the cross section is more than 8 mm and 56 mm or less, the ratio of the length of the longer side to the length of the shorter side is more than 4 and 8 or less, the tensile strength of the flat steel wire is 1900 MPa or more, and the twisting value of the flat steel wire is 12 times or more.
Description
本発明は、電力・通信線、パイプ・ホースなどの耐圧性及び張力を向上させるために使用される二次加工性に優れた高強度平鋼線に関する。
本願は、2013年4月30日に、日本に出願された特願2013-095774号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to a high-strength flat steel wire excellent in secondary workability and used for improving pressure resistance and tension of power / communication wires, pipes / hoses and the like.
This application claims priority based on Japanese Patent Application No. 2013-095774 filed in Japan on April 30, 2013, the contents of which are incorporated herein by reference.
本願は、2013年4月30日に、日本に出願された特願2013-095774号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to a high-strength flat steel wire excellent in secondary workability and used for improving pressure resistance and tension of power / communication wires, pipes / hoses and the like.
This application claims priority based on Japanese Patent Application No. 2013-095774 filed in Japan on April 30, 2013, the contents of which are incorporated herein by reference.
高強度平鋼線に関しては、例えば、特許文献1に、0.90質量%以上の炭素を含有する高強度平鋼線が開示されている。この平鋼線は、長手方向の引張強度が200kgf/mm2程度となる高強度平鋼線である。しかし、一般に、平鋼線の強度が高まるほど、平鋼線の二次加工性が低下する。従来の平鋼線では、強度が優れていたとしても、既に加工限界に達しており、曲げ加工及び捻回加工などの二次加工に供することが困難なことが多い。
With regard to the high-strength flat steel wire, for example, Patent Document 1 discloses a high-strength flat steel wire containing 0.90% by mass or more of carbon. This flat steel wire is a high-strength flat steel wire having a tensile strength in the longitudinal direction of about 200 kgf / mm 2 . However, generally, the secondary workability of a flat steel wire decreases as the strength of the flat steel wire increases. Even if the strength of the conventional flat steel wire is excellent, it has already reached the processing limit and is often difficult to be subjected to secondary processing such as bending and twisting.
一般に、平鋼線は、フレキシブルパイプの補強用などに用いられることが多い。例えば、深海油田から原油を引き上げる際に使用されるフレキシブルパイプには、高い耐圧性及び張力が要求される。そのため、平鋼線には、高強度であることが要求される。一方、平鋼線は、フレキシブルパイプに対してスパイラル状に変形させて使用される。そのため、平鋼線には、捻回加工などに対する二次加工性にも優れることが要求される。二次加工性に乏しい平鋼線では、スパイラル状に変形させる際に、外周から割れが入り、縦割れ状に裂けてしまう場合がある。すなわち、平鋼線が強度と二次加工性とに優れる場合、高い耐圧性及び張力を有するフレキシブルパイプの実現が可能となる。
Generally, flat steel wires are often used for reinforcing flexible pipes. For example, high pressure resistance and tension are required for a flexible pipe used when pulling crude oil from a deep-sea oil field. Therefore, the flat steel wire is required to have high strength. On the other hand, the flat steel wire is used by being deformed into a spiral shape with respect to the flexible pipe. Therefore, flat steel wires are required to have excellent secondary workability with respect to twisting and the like. In a flat steel wire with poor secondary workability, when it is deformed into a spiral shape, cracks may enter from the outer periphery and may be broken into vertical cracks. That is, when the flat steel wire is excellent in strength and secondary workability, a flexible pipe having high pressure resistance and tension can be realized.
本発明は、二次加工性に優れた高強度平鋼線を提供することを目的とする。なお、強度とは、引張降伏強度、引張試験での0.2%耐力、引張最大強度などを意味し、二次加工性とは、捻回特性、引張破断伸びなどを意味する。
An object of the present invention is to provide a high-strength flat steel wire excellent in secondary workability. The strength means tensile yield strength, 0.2% proof stress in a tensile test, maximum tensile strength, and the like, and the secondary workability means twisting property, tensile elongation at break, and the like.
本発明の要旨は、以下のとおりである。
The gist of the present invention is as follows.
(1)本発明の一態様に係る平鋼線は、長手方向に垂直な断面で見た場合に角丸矩形である平鋼線であって、前記断面の短辺が2mm以上7mm以下、前記断面の長辺が8mm超56mm以下、前記短辺に対する前記長辺の比が4超8以下であり、引張試験で得られる降伏強度又は0.2%耐力が1600MPa以上2000MPa以下、引張強度が1900MPa以上、破断伸びが2%以上であり、チャック間距離を500mmとする条件での捻回試験で得られる捻回値が12回以上である。
(1) A flat steel wire according to an aspect of the present invention is a flat steel wire that is a rounded rectangle when viewed in a cross section perpendicular to the longitudinal direction, and a short side of the cross section is 2 mm or more and 7 mm or less, The long side of the cross section is 8 mm to 56 mm or less, the ratio of the long side to the short side is 4 to 8 or less, the yield strength or 0.2% yield strength obtained by a tensile test is 1600 MPa to 2000 MPa, and the tensile strength is 1900 MPa. As described above, the elongation at break is 2% or more, and the twist value obtained by the twist test under the condition that the distance between chucks is 500 mm is 12 times or more.
(2)上記(1)に記載の平鋼線では、前記断面で見た場合に、前記断面の輪郭線から前記断面の重心に向って深さが1μm以内となる領域を前記平鋼線の表層部としたとき、前記表層部で、前記長手方向における圧縮残留応力の平均値が-200MPa以下であってもよい。
(2) In the flat steel wire according to the above (1), when viewed in the cross section, a region having a depth of 1 μm or less from the outline of the cross section toward the center of gravity of the cross section is defined in the flat steel wire. When the surface layer portion is used, an average value of the compressive residual stress in the longitudinal direction may be −200 MPa or less in the surface layer portion.
(3)上記(1)又は(2)に記載の平鋼線では、化学成分が、質量%で、C:0.85%以上1.00%以下、Si:0.80%以上1.30%以下、Mn:0.30%以上0.90%以下、P:0.017%以下、S:0.010%以下、Cu:0.20%以下、Al:0%以上0.10%以下、Ti:0%以上0.05%以下、B:0%以上0.0040%以下、N:0%以上0.0060%以下、Cr:0%以上0.5%以下、V:0%以上0.50%以下を含有し、残部がFe及び不純物からなってもよい。
(3) In the flat steel wire according to the above (1) or (2), the chemical component is mass%, C: 0.85% to 1.00%, Si: 0.80% to 1.30. %: Mn: 0.30% or more and 0.90% or less, P: 0.017% or less, S: 0.010% or less, Cu: 0.20% or less, Al: 0% or more and 0.10% or less Ti: 0% or more and 0.05% or less, B: 0% or more and 0.0040% or less, N: 0% or more and 0.0060% or less, Cr: 0% or more and 0.5% or less, V: 0% or more It may contain 0.50% or less, and the balance may consist of Fe and impurities.
(4)上記(1)~(3)のいずれか1項に記載の平鋼線では、前記化学成分が、質量%で、Al:0.005%以上0.10%以下、Ti:0.003%以上0.05%以下、B:0.0005%以上0.0040%以下、N:0.0015%以上0.0060%以下のうちの少なくとも1つを含有してもよい。
(4) In the flat steel wire according to any one of the above (1) to (3), the chemical component is, by mass%, Al: 0.005% or more and 0.10% or less, Ti: 0.00. It may contain at least one of 003% or more and 0.05% or less, B: 0.0005% or more and 0.0040% or less, and N: 0.0015% or more and 0.0060% or less.
(5)上記(1)~(4)のいずれか1項に記載の平鋼線では、前記化学成分が、質量%で、Cr:0.1%以上0.5%以下、V:0.005%以上0.50%以下のうちの少なくとも1つを含有してもよい。
(5) In the flat steel wire according to any one of the above (1) to (4), the chemical component is, by mass, Cr: 0.1% to 0.5%, V: 0.00. You may contain at least 1 of 005% or more and 0.50% or less.
(6)上記(1)~(5)のいずれか1項に記載の平鋼線では、前記断面の前記短辺が2mm以上6mm以下、前記断面の前記長辺が8mm超48mm以下であってもよい。
(6) In the flat steel wire according to any one of the above (1) to (5), the short side of the cross section is 2 mm to 6 mm, and the long side of the cross section is more than 8 mm and 48 mm or less. Also good.
(7)上記(6)に記載の平鋼線では、前記断面の前記短辺が2mm以上5mm以下、前記断面の前記長辺が8mm超40mm以下であってもよい。
(7) In the flat steel wire described in (6) above, the short side of the cross section may be 2 mm or more and 5 mm or less, and the long side of the cross section may be more than 8 mm and 40 mm or less.
本発明の上記態様によれば、平鋼線の形状などが好ましく制御されるので、例えば捻回加工時に、平鋼線の外周面からの割れの発生と、その進展による平鋼線の縦割れなどが抑制される。その結果、従来の高強度平鋼線と比較して、高い二次加工性を有する高強度平鋼線を得ることが可能である。
According to the above aspect of the present invention, since the shape of the flat steel wire and the like is preferably controlled, for example, during the twisting process, the occurrence of cracks from the outer peripheral surface of the flat steel wire and the vertical crack of the flat steel wire due to its progress Etc. are suppressed. As a result, it is possible to obtain a high-strength flat steel wire having high secondary workability as compared with conventional high-strength flat steel wires.
以下、本発明の好適な実施形態について図面を参照して詳しく説明する。なお、下記する数値限定範囲には、下限値及び上限値がその範囲に含まれる。ただ、下限値に「超」と示す数値限定範囲には下限値が含まれず、上限値に「未満」と示す数値限定範囲には上限値が含まれない。
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the lower limit value and the upper limit value are included in the numerical limit range described below. However, the lower limit value does not include the lower limit value, and the upper limit value does not include the upper limit value.
本発明者らは、長手方向に垂直な断面で見た場合に、断面の形状を角丸矩形とし、断面の短辺に対する断面の長辺の比(長辺÷短辺)を4超8以下に制限することにより、平鋼線の捻回特性の向上が得られることを見出した。平鋼線の外周面、特に角部からの割れが抑制されること、また不均一変形が抑制されることによって、捻回特性が向上すると考えられる。
The inventors of the present invention have a rounded rectangular shape when viewed in a cross section perpendicular to the longitudinal direction, and the ratio of the long side of the cross section to the short side of the cross section (long side / short side) is more than 4 and less than 8 It was found that the twisting characteristics of the flat steel wire can be improved by restricting to. It is considered that the twisting characteristics are improved by suppressing cracks from the outer peripheral surface of the flat steel wire, particularly corners, and suppressing non-uniform deformation.
また、平鋼線の表層部の残留応力を圧縮応力状態に制御することにより、平鋼線の捻回特性が好ましく向上することを見出した。平鋼線の表層部の残留応力が引張応力状態である領域は破壊の起点となりやすいため、表層部で引張残留応力となる領域を低減することによって、捻回特性が好ましく向上すると考えられる。
Further, it has been found that the twisting characteristics of a flat steel wire are preferably improved by controlling the residual stress of the surface portion of the flat steel wire to a compressive stress state. Since the region where the residual stress of the surface layer portion of the flat steel wire is in the tensile stress state is likely to be a starting point of fracture, it is considered that the twisting characteristics are preferably improved by reducing the region that becomes the tensile residual stress in the surface layer portion.
また、平鋼線の化学成分として、C含有量を質量%で1.00%以下に制限すること、またはNを固定する合金化元素を含有することにより、平鋼線の捻回特性がさらに好ましく向上することを見出した。C含有量を制御することで工業的に適用可能な熱処理条件でも均一微細なパーライト組織が形成されるため、捻回特性がさらに好ましく向上すると考えられる。また、鋼中でNを固定することで平鋼線の時効硬化が抑制されるため、平鋼線内の局所的な硬化と、それに伴う不均一変形とが抑制されて、捻回特性がさらに好ましく向上すると考えられる。
Further, by limiting the C content to 1.00% or less by mass% as a chemical component of the flat steel wire, or by containing an alloying element that fixes N, the twisting characteristic of the flat steel wire is further increased. It has been found that it is preferably improved. By controlling the C content, a uniform and fine pearlite structure is formed even under heat treatment conditions that can be applied industrially, and thus it is considered that the twisting characteristics are more preferably improved. Also, fixing N in the steel suppresses the age hardening of the flat steel wire, thereby suppressing local hardening in the flat steel wire and the accompanying non-uniform deformation, further increasing the twisting characteristics. It is thought that it improves preferably.
本実施形態に係る平鋼線は、引張降伏強度又は0.2%耐力が1600MPa以上で、引張最大強度(引張強度)が1900MPa以上という高強度を有すると同時に、引張破断伸びが2%以上で、捻回試験での捻回値が12回以上という優れた二次加工性も有する。
The flat steel wire according to the present embodiment has a high strength of a tensile yield strength or 0.2% proof stress of 1600 MPa or more and a maximum tensile strength (tensile strength) of 1900 MPa or more, and at the same time a tensile breaking elongation of 2% or more. Also, it has excellent secondary workability such that the twist value in the twist test is 12 times or more.
一般に、構造用鋼では引張強度が1000MPa以上の場合、高強度鋼とみなされる。また、一般に、丸鋼線では捻回値が12回以上の場合、捻回特性に優れるとみなされる。すなわち、本実施形態に係る平鋼線は、強度と二次加工性という相反する2つの特性を、同時に満足していると言える。例えば、本実施形態に係る平鋼線を用いることで、高い耐圧性及び張力を有するフレキシブルパイプの実現が可能となる。
Generally, structural steel is regarded as high-strength steel when the tensile strength is 1000 MPa or more. In general, in the case of a round steel wire, when the twist value is 12 times or more, it is considered that the twist characteristics are excellent. That is, it can be said that the flat steel wire according to the present embodiment simultaneously satisfies two contradictory properties of strength and secondary workability. For example, by using the flat steel wire according to the present embodiment, a flexible pipe having high pressure resistance and tension can be realized.
以下、本実施形態に係る平鋼線の形状について詳述する。
Hereinafter, the shape of the flat steel wire according to this embodiment will be described in detail.
本実施形態に係る平鋼線は、長手方向に垂直な断面で見た場合に、形状が角丸矩形であり、断面の短辺が2mm以上7mm以下であり、断面の長辺が8mm超56mm以下であり、上記短辺に対する上記長辺の比が4超8以下である。
The flat steel wire according to the present embodiment has a rounded rectangular shape when viewed in a cross section perpendicular to the longitudinal direction, the short side of the cross section is 2 mm or more and 7 mm or less, and the long side of the cross section is more than 8 mm and 56 mm. The ratio of the long side to the short side is more than 4 and 8 or less.
なお、一般に、平鋼線では、平鋼線の長手方向に垂直な断面で見た場合に、寸法の短い方(短辺)を「厚み」、長い方(長辺)を「幅」と称する。本実施形態に係る平鋼線では、角丸矩形である上記断面の短い方の辺を、短辺(厚み)と定義する。そして、この短辺の長さは、上記断面の角部が丸みを有さない略直角であると仮定した場合の角部から角部までの長さと定義する。同様に、本実施形態に係る平鋼線では、角丸矩形である上記断面の長い方の辺を、長辺(幅)と定義する。そして、この長辺の長さは、上記断面の角部が丸みを有さない略直角であると仮定した場合の角部から角部までの長さと定義する。図1に、本実施形態に係る平鋼線1の上記断面での短辺(厚み)及び長辺(幅)を模式的に示す。
In general, in a flat steel wire, when viewed in a cross section perpendicular to the longitudinal direction of the flat steel wire, the shorter dimension (short side) is referred to as “thickness” and the longer dimension (long side) is referred to as “width”. . In the flat steel wire according to the present embodiment, the shorter side of the cross section that is a rounded rectangle is defined as the short side (thickness). The length of the short side is defined as the length from the corner to the corner when the corner of the cross section is assumed to be a substantially right angle without roundness. Similarly, in the flat steel wire according to the present embodiment, the longer side of the cross section that is a rounded rectangle is defined as the long side (width). The length of the long side is defined as the length from the corner to the corner when the corner of the cross section is assumed to be a substantially right angle without roundness. In FIG. 1, the short side (thickness) and the long side (width) in the said cross section of the flat steel wire 1 which concern on this embodiment are shown typically.
本実施形態に係る平鋼線1は、長手方向に垂直な断面で見た場合に、矩形状をなすとともに、各角部が円弧状をなす。すなわち、断面形状が、角部に丸みを有する角丸矩形となる。断面形状が角丸矩形であることによって、二次加工時に角部を起点とする破壊が抑制される。また、断面形状が角丸矩形であることによって、平鋼線1をパイプに対してスパイラル状に変形させたときに、隣り合う平鋼線1の角部どうしによる干渉が抑制される。
The flat steel wire 1 according to the present embodiment has a rectangular shape when viewed in a cross section perpendicular to the longitudinal direction, and each corner portion has an arc shape. That is, the cross-sectional shape is a rounded rectangle with rounded corners. Since the cross-sectional shape is a rounded rectangle, the breakage starting from the corner is suppressed during the secondary processing. Moreover, when the cross-sectional shape is a rounded rectangular shape, when the flat steel wire 1 is deformed in a spiral shape with respect to the pipe, interference between corner portions of the adjacent flat steel wires 1 is suppressed.
本実施形態に係る平鋼線1では、製造時の圧延ロールの表面安定性や圧延時の反力を考慮すると、また平鋼線1の強度の制御を考慮すると、平鋼線1の厚みは7mmが上限である。また、捻回加工を安定的に行うためには、平鋼線1の厚みは、2mm以上が必要である。即ち、本実施形態に係る平鋼線1の厚みは2mm以上7mm以下である。
In the flat steel wire 1 according to the present embodiment, considering the surface stability of the rolling roll during production and the reaction force during rolling, and considering the control of the strength of the flat steel wire 1, the thickness of the flat steel wire 1 is The upper limit is 7 mm. Moreover, in order to perform a twisting process stably, the thickness of the flat steel wire 1 needs to be 2 mm or more. That is, the thickness of the flat steel wire 1 according to this embodiment is 2 mm or more and 7 mm or less.
また、本発明者らは、12回以上の捻回値を確保するための検討を行った結果、幅/厚み比(短辺に対する長辺の比)を4超8以下にする必要があることを見出した。短辺に対する長辺の比が8以下のとき、不均一変形が抑制されるため、捻回特性が向上すると考えられる。また、短辺に対する長辺の比が4以下であると、強度確保のために炭素及び合金元素を必要以上に含有させる必要が生じ、その結果、平鋼線1の延性及び二次加工性を低下させる。
In addition, as a result of studies to ensure a twist value of 12 times or more, the present inventors need to make the width / thickness ratio (ratio of long side to short side) more than 4 and 8 or less. I found. When the ratio of the long side to the short side is 8 or less, the non-uniform deformation is suppressed, so that the twisting characteristic is considered to be improved. Further, if the ratio of the long side to the short side is 4 or less, it is necessary to contain carbon and alloy elements more than necessary for securing the strength. As a result, the ductility and secondary workability of the flat steel wire 1 are improved. Reduce.
上記した平鋼線1の厚み(短辺)と、幅/厚み比(短辺に対する長辺の比)とに基づいて、本実施形態に係る平鋼線1の幅(長辺)は、8mm超56mm以下とすればよい。
Based on the thickness (short side) of the flat steel wire 1 and the width / thickness ratio (ratio of the long side to the short side), the width (long side) of the flat steel wire 1 according to this embodiment is 8 mm. What is necessary is just to be super 56 mm or less.
また、本実施形態に係る平鋼線1は、長手方向に垂直な断面で見た場合に、断面の短辺が2mm以上6mm以下であり、断面の長辺が8mm超48mm以下であることが好ましく、断面の短辺が2mm以上5mm以下であり、断面の長辺が8mm超40mm以下であることがさらに好ましい。また、本実施形態に係る平鋼線1は、幅/厚み比の下限が5以上であることが好ましく、幅/厚み比の上限が7以下であることが好ましい。
Moreover, when the flat steel wire 1 which concerns on this embodiment is seen in the cross section perpendicular | vertical to a longitudinal direction, the short side of a cross section is 2 mm or more and 6 mm or less, and the long side of a cross section is 8 mm over 48 mm or less. More preferably, the short side of the cross section is 2 mm or more and 5 mm or less, and the long side of the cross section is more than 8 mm and 40 mm or less. Moreover, as for the flat steel wire 1 which concerns on this embodiment, it is preferable that the minimum of width / thickness ratio is 5 or more, and it is preferable that the upper limit of width / thickness ratio is 7 or less.
以下、本実施形態に係る平鋼線1の強度と捻回特性とについて詳述する。
Hereinafter, the strength and twisting characteristics of the flat steel wire 1 according to the present embodiment will be described in detail.
本実施形態に係る平鋼線1は、1900MPa以上の引張強度を有する。この引張強度の上限は、特に限定されないが、2400MPaとしてもよい。
The flat steel wire 1 according to the present embodiment has a tensile strength of 1900 MPa or more. The upper limit of the tensile strength is not particularly limited, but may be 2400 MPa.
本実施形態に係る平鋼線1では、延性を確保するため、破断伸びを2%以上とする。この破断伸びの上限は、特に限定されないが、5%としてもよい。さらに、本実施形態に係る平鋼線1では、降伏後の延びを確保するため、降伏強度又は0.2%耐力を1600MPa以上とする。この降伏強度又は0.2%耐力の上限は、特に限定されないが、2000MPaとしてもよい。また、降伏強度又は0.2%耐力は、引張強度よりも低い値であることが好ましい。具体的には、引張強度に対する降伏強度又は0.2%耐力の比(降伏強度又は0.2%耐力÷引張強度)が、0.8以上0.95以下であることが好ましい。
In the flat steel wire 1 according to this embodiment, the elongation at break is set to 2% or more in order to ensure ductility. The upper limit of the elongation at break is not particularly limited, but may be 5%. Furthermore, in the flat steel wire 1 which concerns on this embodiment, in order to ensure the extension after a yield, yield strength or 0.2% yield strength shall be 1600 Mpa or more. The upper limit of the yield strength or 0.2% proof stress is not particularly limited, but may be 2000 MPa. Moreover, it is preferable that yield strength or 0.2% yield strength is a value lower than tensile strength. Specifically, the ratio of yield strength or 0.2% yield strength to tensile strength (yield strength or 0.2% yield strength / tensile strength) is preferably 0.8 or more and 0.95 or less.
上記した機械的特性は、圧延条件などの製造条件によって、制御すればよい。例えば、圧延前の鋼線材の線径と、圧延時の圧延温度や圧下率とを制御することで、上記した機械的特性を制御すればよい。また、必要に応じて、平鋼線1の化学成分を制御することで、上記した機械的特性を制御してもよい。
The above-described mechanical characteristics may be controlled according to manufacturing conditions such as rolling conditions. For example, the above-described mechanical characteristics may be controlled by controlling the wire diameter of the steel wire before rolling and the rolling temperature and rolling reduction during rolling. Moreover, you may control an above-described mechanical characteristic by controlling the chemical component of the flat steel wire 1 as needed.
また、本実施形態に係る平鋼線1は、平鋼線1の形状などが好ましく制御されるので、優れた二次加工性を有する。具体的には、チャック間距離を500mmとする条件での捻回試験で、12回以上の捻回加工が可能である。このように本実施形態に係る平鋼線1では、強度と二次加工性とが同時に優れる。図2に、捻回加工後の本実施形態に係る平鋼線1を示す。図2に示すように、本実施形態に係る平鋼線1では、高強度であるにもかかわらず、優れた捻回特性を有することが確認される。捻回値の上限は、特に限定されないが、25回としてもよい。
Further, the flat steel wire 1 according to this embodiment has excellent secondary workability because the shape of the flat steel wire 1 and the like are preferably controlled. Specifically, in a twist test under the condition that the distance between chucks is set to 500 mm, a twist process of 12 times or more can be performed. Thus, in the flat steel wire 1 which concerns on this embodiment, intensity | strength and secondary workability are excellent simultaneously. FIG. 2 shows a flat steel wire 1 according to this embodiment after twisting. As shown in FIG. 2, it is confirmed that the flat steel wire 1 according to the present embodiment has excellent twist characteristics despite high strength. The upper limit of the twist value is not particularly limited, but may be 25 times.
以下、本実施形態に係る平鋼線1の残留応力状態について詳述する。なお、残留応力は、その値が正であるとき引張残留応力であること、その値が負であるとき圧縮残留応力であることを意味する。
Hereinafter, the residual stress state of the flat steel wire 1 according to the present embodiment will be described in detail. The residual stress means a tensile residual stress when the value is positive, and a compressive residual stress when the value is negative.
本実施形態に係る平鋼線1では、平鋼線1の表層部2の残留応力の平均値を圧縮応力状態に制御することにより、平鋼線1の捻回特性が好ましく向上する。具体的には、長手方向に垂直な断面で見た場合に、断面の輪郭線から断面の重心に向って深さが1μm以内となる領域を平鋼線1の表層部2としたとき、この表層部2で、長手方向における残留応力の平均値が-200MPa以下であってもよい。表層部2の残留応力の平均値が-200MPa以下であるとき、平鋼線1の捻回特性が好ましく向上する。なお、残留応力の平均値が-200MPa以下とは、例えば、残留応力の平均値が-220MPaであったり、-250MPaであったりすることを意味する。また、残留応力の平均値の下限は、特に限定されないが、-1200MPaとしてもよい。すなわち、残留応力の平均値が、-1200MPa以上-200MPa以下であることが好ましい。なお、平鋼線1の表層部2の局所領域で残留応力が引張応力状態であったとしても、平鋼線1の表層部2の残留応力が、平均として、圧縮応力状態であり、その値が-200MPa以下であれば、上記効果を好ましく得ることができる。
In the flat steel wire 1 according to the present embodiment, the twist characteristic of the flat steel wire 1 is preferably improved by controlling the average value of the residual stress of the surface layer portion 2 of the flat steel wire 1 to a compressive stress state. Specifically, when a region whose depth is within 1 μm from the contour line of the cross section toward the center of gravity of the cross section when viewed in a cross section perpendicular to the longitudinal direction is the surface layer portion 2 of the flat steel wire 1, In the surface layer portion 2, the average value of the residual stress in the longitudinal direction may be −200 MPa or less. When the average value of the residual stress of the surface layer portion 2 is −200 MPa or less, the twisting characteristics of the flat steel wire 1 are preferably improved. Note that the average value of residual stress being −200 MPa or less means that the average value of residual stress is −220 MPa or −250 MPa, for example. Further, the lower limit of the average value of the residual stress is not particularly limited, but may be −1200 MPa. That is, the average value of residual stress is preferably −1200 MPa or more and −200 MPa or less. In addition, even if the residual stress is in the tensile stress state in the local region of the surface layer portion 2 of the flat steel wire 1, the residual stress of the surface layer portion 2 of the flat steel wire 1 is, as an average, a compressive stress state, and its value When the value is −200 MPa or less, the above effect can be preferably obtained.
図1に、長手方向に垂直な断面で見た場合の表層部2を模式的に示す。また、図3に、表層部2の残留応力の平均値と、捻回試験での捻回値との関係を示す。この図3には、表層部2の圧縮残留応力の平均値が-200MPa以下であるときに、平鋼線1の捻回特性が臨界的に向上することが示される。
FIG. 1 schematically shows the surface layer portion 2 when viewed in a cross section perpendicular to the longitudinal direction. FIG. 3 shows the relationship between the average value of the residual stress of the surface layer portion 2 and the twist value in the twist test. FIG. 3 shows that the twisting characteristics of the flat steel wire 1 are critically improved when the average value of the compressive residual stress of the surface layer portion 2 is −200 MPa or less.
平鋼線1の表層部2の残留応力が引張応力状態である領域は破壊の起点となりやすいため、表層部2を平均値が-200MPa以下の圧縮残留応力に制御することが好ましい。平鋼線1の表層部2の残留応力を圧縮応力状態に制御するには、ショットブラストなどを施すことが好ましい。また、表層部2での圧縮残留応力の平均値は、-300MPa以下または-400MPa以下であることがさらに好ましい。また、平鋼線1の表層部2は、上記重心に向かって深さが、2μm以内または3μm以内となる領域であることがさらに好ましい。
Since the region where the residual stress of the surface layer portion 2 of the flat steel wire 1 is in a tensile stress state is likely to be a starting point of fracture, it is preferable to control the surface layer portion 2 to a compressive residual stress having an average value of −200 MPa or less. In order to control the residual stress of the surface layer portion 2 of the flat steel wire 1 to a compressive stress state, it is preferable to perform shot blasting or the like. The average value of the compressive residual stress in the surface layer part 2 is more preferably −300 MPa or less or −400 MPa or less. Further, the surface layer portion 2 of the flat steel wire 1 is more preferably a region whose depth is within 2 μm or within 3 μm toward the center of gravity.
以下、本実施形態に係る平鋼線1の好ましい化学成分について詳述する。なお、以下の説明において、各元素の含有量の「%」は、「質量%」を意味する。
Hereinafter, preferred chemical components of the flat steel wire 1 according to this embodiment will be described in detail. In the following description, “%” of the content of each element means “mass%”.
本実施形態に係る平鋼線1の化学成分は、質量%で、C:0.85%以上1.00%以下、Si:0.80%以上1.30%以下、Mn:0.30%以上0.90%以下、P:0.017%以下、S:0.010%以下、Cu:0.20%以下、Al:0%以上0.10%以下、Ti:0%以上0.05%以下、B:0%以上0.0040%以下、N:0%以上0.0060%以下、Cr:0%以上0.5%以下、V:0%以上0.50%以下であり、残部がFe及び不純物からなることが好ましい。
The chemical composition of the flat steel wire 1 according to the present embodiment is mass%, C: 0.85% to 1.00%, Si: 0.80% to 1.30%, Mn: 0.30% 0.90% or less, P: 0.017% or less, S: 0.010% or less, Cu: 0.20% or less, Al: 0% or more and 0.10% or less, Ti: 0% or more and 0.05 %: B: 0% to 0.0040%, N: 0% to 0.0060%, Cr: 0% to 0.5%, V: 0% to 0.50%, the balance Is preferably composed of Fe and impurities.
本実施形態に係る平鋼線1の上記化学成分のうち、C、Si、Mnが基本元素である。
Among the chemical components of the flat steel wire 1 according to this embodiment, C, Si, and Mn are basic elements.
C:0.85%以上1.00%以下
C(炭素)は、パーライト鋼のセメンタイト分率を上げることで、パーライト鋼の強度を向上させる元素である。一般に、パテンティングなどの製造条件を最適化してパーライトのラメラ間隔を制御することによって、または加工硬化によって、パーライト鋼の強度を向上させることが可能である。ただ、C含有量が0.85%以上のとき、延性を確保しながら、引張強度を1900MPa以上にすることができるので好ましい。したがって、C含有量の下限を0.85%としてもよい。また、C含有量が1.00%以下のとき、局所的な偏析に起因する加工時の割れを抑制できるので好ましい。したがって、C含有量の上限を1.00%としてもよい。 C: 0.85% or more and 1.00% or less C (carbon) is an element that improves the strength of pearlite steel by increasing the cementite fraction of pearlite steel. In general, it is possible to improve the strength of pearlite steel by optimizing manufacturing conditions such as patenting and controlling the lamella spacing of pearlite, or by work hardening. However, it is preferable that the C content is 0.85% or more because the tensile strength can be 1900 MPa or more while ensuring ductility. Therefore, the lower limit of the C content may be 0.85%. Moreover, when C content is 1.00% or less, since the crack at the time of the process resulting from local segregation can be suppressed, it is preferable. Therefore, the upper limit of the C content may be 1.00%.
C(炭素)は、パーライト鋼のセメンタイト分率を上げることで、パーライト鋼の強度を向上させる元素である。一般に、パテンティングなどの製造条件を最適化してパーライトのラメラ間隔を制御することによって、または加工硬化によって、パーライト鋼の強度を向上させることが可能である。ただ、C含有量が0.85%以上のとき、延性を確保しながら、引張強度を1900MPa以上にすることができるので好ましい。したがって、C含有量の下限を0.85%としてもよい。また、C含有量が1.00%以下のとき、局所的な偏析に起因する加工時の割れを抑制できるので好ましい。したがって、C含有量の上限を1.00%としてもよい。 C: 0.85% or more and 1.00% or less C (carbon) is an element that improves the strength of pearlite steel by increasing the cementite fraction of pearlite steel. In general, it is possible to improve the strength of pearlite steel by optimizing manufacturing conditions such as patenting and controlling the lamella spacing of pearlite, or by work hardening. However, it is preferable that the C content is 0.85% or more because the tensile strength can be 1900 MPa or more while ensuring ductility. Therefore, the lower limit of the C content may be 0.85%. Moreover, when C content is 1.00% or less, since the crack at the time of the process resulting from local segregation can be suppressed, it is preferable. Therefore, the upper limit of the C content may be 1.00%.
Si:0.80%以上1.30%以下
Si(シリコン)は、鋼の精錬時の脱酸元素であり、フェライトを固溶強化させる元素である。これらの効果を得るために、Si含有量の下限を0.80%としてもよい。また、Si含有量が1.30%以下のとき、熱処理時の恒温変態のノーズ温度を好ましく制御できる。したがって、Si含有量の上限を1.30%としてもよい。 Si: 0.80% or more and 1.30% or less Si (silicon) is a deoxidizing element at the time of refining steel, and is an element that solidifies and strengthens ferrite. In order to obtain these effects, the lower limit of the Si content may be 0.80%. Moreover, when Si content is 1.30% or less, the nose temperature of the isothermal transformation at the time of heat processing can be controlled preferably. Therefore, the upper limit of the Si content may be 1.30%.
Si(シリコン)は、鋼の精錬時の脱酸元素であり、フェライトを固溶強化させる元素である。これらの効果を得るために、Si含有量の下限を0.80%としてもよい。また、Si含有量が1.30%以下のとき、熱処理時の恒温変態のノーズ温度を好ましく制御できる。したがって、Si含有量の上限を1.30%としてもよい。 Si: 0.80% or more and 1.30% or less Si (silicon) is a deoxidizing element at the time of refining steel, and is an element that solidifies and strengthens ferrite. In order to obtain these effects, the lower limit of the Si content may be 0.80%. Moreover, when Si content is 1.30% or less, the nose temperature of the isothermal transformation at the time of heat processing can be controlled preferably. Therefore, the upper limit of the Si content may be 1.30%.
Mn:0.30%以上0.90%以下
Mn(マンガン)は、固溶強化元素であり、靭性を向上させるとともに、焼入れ性を向上させる元素である。これらの効果を得るために、Mn含有量の下限を0.30%としてもよい。また、Mn含有量が0.90%以下のとき、平鋼線1の中心部の変態遅れを抑制できるので好ましい。したがって、Mn含有量の上限を0.90%としてもよい。 Mn: 0.30% or more and 0.90% or less Mn (manganese) is a solid solution strengthening element, and is an element that improves toughness and hardenability. In order to obtain these effects, the lower limit of the Mn content may be 0.30%. Moreover, when Mn content is 0.90% or less, since the transformation delay of the center part of theflat steel wire 1 can be suppressed, it is preferable. Therefore, the upper limit of the Mn content may be 0.90%.
Mn(マンガン)は、固溶強化元素であり、靭性を向上させるとともに、焼入れ性を向上させる元素である。これらの効果を得るために、Mn含有量の下限を0.30%としてもよい。また、Mn含有量が0.90%以下のとき、平鋼線1の中心部の変態遅れを抑制できるので好ましい。したがって、Mn含有量の上限を0.90%としてもよい。 Mn: 0.30% or more and 0.90% or less Mn (manganese) is a solid solution strengthening element, and is an element that improves toughness and hardenability. In order to obtain these effects, the lower limit of the Mn content may be 0.30%. Moreover, when Mn content is 0.90% or less, since the transformation delay of the center part of the
本実施形態に係る平鋼線1は、化学成分として、不純物を含有する。なお、「不純物」とは、鋼を工業的に製造する際に、原料としての鉱石、スクラップ、または製造環境等から混入するものを指す。これら不純物のなかで、P、S、Cuは、上記効果を十分に発揮させるために、以下のように制限することが好ましい。また、不純物の含有量は少ないことが好ましいので、下限値を制限する必要がなく、不純物の下限値が0%でもよい。
The flat steel wire 1 according to the present embodiment contains impurities as chemical components. The “impurity” refers to a material mixed from ore as a raw material, scrap, or a production environment when steel is industrially produced. Among these impurities, P, S, and Cu are preferably limited as follows in order to sufficiently exhibit the above effects. Moreover, since it is preferable that there is little content of an impurity, it is not necessary to restrict | limit a lower limit and the lower limit of an impurity may be 0%.
P:0.017%以下
P(燐)は、不純物である。P含有量が0.017%以下のとき、鋼の脆化を抑制し、平鋼線1の加工時の割れを抑制できるので好ましい。したがって、P含有量を0.017%以下に制限してもよい。 P: 0.017% or less P (phosphorus) is an impurity. When the P content is 0.017% or less, it is preferable because the embrittlement of the steel can be suppressed and cracking during processing of theflat steel wire 1 can be suppressed. Therefore, the P content may be limited to 0.017% or less.
P(燐)は、不純物である。P含有量が0.017%以下のとき、鋼の脆化を抑制し、平鋼線1の加工時の割れを抑制できるので好ましい。したがって、P含有量を0.017%以下に制限してもよい。 P: 0.017% or less P (phosphorus) is an impurity. When the P content is 0.017% or less, it is preferable because the embrittlement of the steel can be suppressed and cracking during processing of the
S:0.010%以下
S(硫黄)は、不純物である。Sは、鋼中のMnと結合しMnSを形成する。またSは、鋼の精錬-凝固過程で鋼片の中心部に偏析し、この中心部で多くのMnSを形成し、鋼を脆化させる。S含有量が0.010%以下のとき、平鋼線1の中心部を起点とした破断を抑制できるので好ましい。したがって、S含有量を0.010%以下に制限してもよい。 S: 0.010% or less S (sulfur) is an impurity. S combines with Mn in steel to form MnS. S segregates at the center of the steel slab during the refining-solidification process of the steel, and a large amount of MnS is formed at this center to embrittle the steel. When S content is 0.010% or less, since the fracture | rupture which started from the center part of theflat steel wire 1 can be suppressed, it is preferable. Therefore, the S content may be limited to 0.010% or less.
S(硫黄)は、不純物である。Sは、鋼中のMnと結合しMnSを形成する。またSは、鋼の精錬-凝固過程で鋼片の中心部に偏析し、この中心部で多くのMnSを形成し、鋼を脆化させる。S含有量が0.010%以下のとき、平鋼線1の中心部を起点とした破断を抑制できるので好ましい。したがって、S含有量を0.010%以下に制限してもよい。 S: 0.010% or less S (sulfur) is an impurity. S combines with Mn in steel to form MnS. S segregates at the center of the steel slab during the refining-solidification process of the steel, and a large amount of MnS is formed at this center to embrittle the steel. When S content is 0.010% or less, since the fracture | rupture which started from the center part of the
Cu:0.20%以下
Cu(銅)は、主にスクラップなどから混入する不純物である。Cuは、固溶強化によって鋼を硬化させる作用も有する。しかし、Cu含有量が0.20%以下のとき、平鋼線1の加工性の著しく低下を抑制できるので好ましい。したがって、Cu含有量を0.20%以下に制限してもよい。 Cu: 0.20% or less Cu (copper) is an impurity mainly mixed from scrap or the like. Cu also has an effect of hardening steel by solid solution strengthening. However, when the Cu content is 0.20% or less, the workability of theflat steel wire 1 can be remarkably reduced, which is preferable. Therefore, the Cu content may be limited to 0.20% or less.
Cu(銅)は、主にスクラップなどから混入する不純物である。Cuは、固溶強化によって鋼を硬化させる作用も有する。しかし、Cu含有量が0.20%以下のとき、平鋼線1の加工性の著しく低下を抑制できるので好ましい。したがって、Cu含有量を0.20%以下に制限してもよい。 Cu: 0.20% or less Cu (copper) is an impurity mainly mixed from scrap or the like. Cu also has an effect of hardening steel by solid solution strengthening. However, when the Cu content is 0.20% or less, the workability of the
上述のように、本実施形態に係る平鋼線1の化学成分は、基本元素と、残部としてFe及び不純物を含有する。しかし、本実施形態に係る平鋼線1は、残部であるFeの一部に代えて、選択元素として、Al、Ti、B、N、Cr、Vを含有してもよい。これらの選択元素は、その目的に応じて含有させればよい。よって、これらの選択元素の下限値を制限する必要がなく、下限値が0%でもよい。また、これらの選択元素が不純物として含有されても、上記効果は損なわれない。
As described above, the chemical components of the flat steel wire 1 according to the present embodiment contain the basic elements and the balance Fe and impurities. However, the flat steel wire 1 according to the present embodiment may contain Al, Ti, B, N, Cr, and V as selective elements instead of a part of Fe that is the balance. These selective elements may be contained depending on the purpose. Therefore, it is not necessary to limit the lower limit values of these selected elements, and the lower limit value may be 0%. Moreover, even if these selective elements are contained as impurities, the above effects are not impaired.
Al:0%以上0.10%以下
Al(アルミニウム)は、鋼の精錬時の脱酸元素であり、鋼中のNと結合して化合物を形成する元素である。Alが鋼中のNを固定することで、平鋼線1の時効硬化が抑制される。また、AlとBとを同時に含有する場合、Alが鋼中のNを固定することで、鋼中の固溶B量を増加させる。したがって、必要に応じて、Al含有量を0%以上0.10%以下としてもよい。好ましいAl含有量の下限は0.005%である。また、Al含有量が0.10%以下のとき、Al2O3がクラスターを形成することに起因する加工時の割れを抑制できるので好ましい。 Al: 0% or more and 0.10% or less Al (aluminum) is a deoxidizing element when refining steel, and is an element that forms a compound by combining with N in steel. The age hardening of theflat steel wire 1 is suppressed by Al fixing N in the steel. Moreover, when containing Al and B simultaneously, Al increases the amount of solute B in steel by fixing N in steel. Therefore, if necessary, the Al content may be 0% or more and 0.10% or less. The lower limit of the preferable Al content is 0.005%. Further, when the Al content is less 0.10%, since the cracking during processing due to the Al 2 O 3 to form a cluster can be suppressed preferred.
Al(アルミニウム)は、鋼の精錬時の脱酸元素であり、鋼中のNと結合して化合物を形成する元素である。Alが鋼中のNを固定することで、平鋼線1の時効硬化が抑制される。また、AlとBとを同時に含有する場合、Alが鋼中のNを固定することで、鋼中の固溶B量を増加させる。したがって、必要に応じて、Al含有量を0%以上0.10%以下としてもよい。好ましいAl含有量の下限は0.005%である。また、Al含有量が0.10%以下のとき、Al2O3がクラスターを形成することに起因する加工時の割れを抑制できるので好ましい。 Al: 0% or more and 0.10% or less Al (aluminum) is a deoxidizing element when refining steel, and is an element that forms a compound by combining with N in steel. The age hardening of the
なお、TiもAlと同様の効果を有するので、Ti含有量に応じてAl含有量を低減することができる。この場合も、上記と同様の効果が得られる。
In addition, since Ti also has the same effect as Al, Al content can be reduced according to Ti content. In this case, the same effect as described above can be obtained.
Ti:0%以上0.05%以下
Ti(チタニウム)は、Alと同様に、鋼の精錬時の脱酸元素であり、鋼中のNと結合して化合物を形成する元素である。Tiが鋼中のNを固定することで、平鋼線1の時効硬化が抑制される。また、TiとBとを同時に含有する場合、Tiが鋼中のNを固定することで、鋼中の固溶B量を増加させる。したがって、必要に応じて、Ti含有量を0%以上0.05%以下としてもよい。好ましいTi含有量の下限は0.003%である。また、Ti含有量が0.05%以下のとき、TiCが増加することに起因する加工時の割れを抑制できるので好ましい。 Ti: 0% or more and 0.05% or less Ti (titanium), like Al, is a deoxidizing element during refining of steel, and is an element that forms a compound by combining with N in steel. When Ti fixes N in the steel, age hardening of theflat steel wire 1 is suppressed. When Ti and B are contained simultaneously, Ti fixes N in the steel, thereby increasing the amount of solute B in the steel. Therefore, the Ti content may be 0% or more and 0.05% or less as necessary. The lower limit of the preferable Ti content is 0.003%. Moreover, when Ti content is 0.05% or less, since the crack at the time of the process resulting from TiC increasing can be suppressed, it is preferable.
Ti(チタニウム)は、Alと同様に、鋼の精錬時の脱酸元素であり、鋼中のNと結合して化合物を形成する元素である。Tiが鋼中のNを固定することで、平鋼線1の時効硬化が抑制される。また、TiとBとを同時に含有する場合、Tiが鋼中のNを固定することで、鋼中の固溶B量を増加させる。したがって、必要に応じて、Ti含有量を0%以上0.05%以下としてもよい。好ましいTi含有量の下限は0.003%である。また、Ti含有量が0.05%以下のとき、TiCが増加することに起因する加工時の割れを抑制できるので好ましい。 Ti: 0% or more and 0.05% or less Ti (titanium), like Al, is a deoxidizing element during refining of steel, and is an element that forms a compound by combining with N in steel. When Ti fixes N in the steel, age hardening of the
B:0%以上0.0040%以下
B(ホウ素)は、オーステナイト中に固溶し、焼入れ性を向上させる元素である。したがって、必要に応じて、B含有量を0%以上0.0040%以下としてもよい。好ましいB含有量の下限は0.0005%である。また、B含有量が0.0040%以下のとき、Fe23(C、B)6などの析出物に起因する加工時の割れを抑制できるので好ましい。 B: 0% or more and 0.0040% or less B (boron) is an element that dissolves in austenite and improves hardenability. Therefore, the B content may be 0% or more and 0.0040% or less as necessary. The lower limit of the preferable B content is 0.0005%. Also, when the B content is less 0.0040%, Fe 23 (C, B) since the cracking during processing due to precipitation of such 6 can be suppressed preferred.
B(ホウ素)は、オーステナイト中に固溶し、焼入れ性を向上させる元素である。したがって、必要に応じて、B含有量を0%以上0.0040%以下としてもよい。好ましいB含有量の下限は0.0005%である。また、B含有量が0.0040%以下のとき、Fe23(C、B)6などの析出物に起因する加工時の割れを抑制できるので好ましい。 B: 0% or more and 0.0040% or less B (boron) is an element that dissolves in austenite and improves hardenability. Therefore, the B content may be 0% or more and 0.0040% or less as necessary. The lower limit of the preferable B content is 0.0005%. Also, when the B content is less 0.0040%, Fe 23 (C, B) since the cracking during processing due to precipitation of such 6 can be suppressed preferred.
N:0%以上0.0060%以下
N(窒素)は、鋼中のAl、Ti、Bと結合して窒化物を形成し、加熱時にオーステナイト粒径の粗大化を抑制する元素である。したがって、必要に応じて、N含有量を0%以上0.0060%以下としてもよい。好ましいN含有量の下限は0.0015%である。また、N含有量が0.0060%以下のとき、Al、Ti、Bと結合しない過剰なフリーNに起因する時効硬化が抑制され、その結果、平鋼線1の延性低下が抑制されるので好ましい。 N: 0% or more and 0.0060% or less N (nitrogen) is an element that combines with Al, Ti, and B in steel to form a nitride, and suppresses the coarsening of the austenite grain size during heating. Therefore, the N content may be 0% or more and 0.0060% or less as necessary. The lower limit of the preferable N content is 0.0015%. Further, when the N content is 0.0060% or less, age hardening due to excessive free N that does not bond with Al, Ti, B is suppressed, and as a result, the ductility reduction of theflat steel wire 1 is suppressed. preferable.
N(窒素)は、鋼中のAl、Ti、Bと結合して窒化物を形成し、加熱時にオーステナイト粒径の粗大化を抑制する元素である。したがって、必要に応じて、N含有量を0%以上0.0060%以下としてもよい。好ましいN含有量の下限は0.0015%である。また、N含有量が0.0060%以下のとき、Al、Ti、Bと結合しない過剰なフリーNに起因する時効硬化が抑制され、その結果、平鋼線1の延性低下が抑制されるので好ましい。 N: 0% or more and 0.0060% or less N (nitrogen) is an element that combines with Al, Ti, and B in steel to form a nitride, and suppresses the coarsening of the austenite grain size during heating. Therefore, the N content may be 0% or more and 0.0060% or less as necessary. The lower limit of the preferable N content is 0.0015%. Further, when the N content is 0.0060% or less, age hardening due to excessive free N that does not bond with Al, Ti, B is suppressed, and as a result, the ductility reduction of the
Cr:0%以上0.5%以下
Cr(クロミウム)は、パーライトのラメラ間隔を小さくして、パーライト鋼の強度を向上させる元素である。また、Crは、伸線加工時の強度上昇に寄与する元素である。したがって、必要に応じて、Cr含有量を0%以上0.5%以下としてもよい。好ましいCr含有量の下限は0.1%である。また、Cr含有量が0.5%以下のとき、パーライト変態終了時間が長くなることに起因する生産性の低下を抑制できるので好ましい。 Cr: 0% or more and 0.5% or less Cr (chromium) is an element that reduces the lamella spacing of pearlite and improves the strength of pearlite steel. Cr is an element that contributes to an increase in strength during wire drawing. Therefore, the Cr content may be 0% or more and 0.5% or less as necessary. The lower limit of the preferable Cr content is 0.1%. Moreover, when Cr content is 0.5% or less, since the fall of productivity resulting from pearlite transformation completion time becoming long can be suppressed, it is preferable.
Cr(クロミウム)は、パーライトのラメラ間隔を小さくして、パーライト鋼の強度を向上させる元素である。また、Crは、伸線加工時の強度上昇に寄与する元素である。したがって、必要に応じて、Cr含有量を0%以上0.5%以下としてもよい。好ましいCr含有量の下限は0.1%である。また、Cr含有量が0.5%以下のとき、パーライト変態終了時間が長くなることに起因する生産性の低下を抑制できるので好ましい。 Cr: 0% or more and 0.5% or less Cr (chromium) is an element that reduces the lamella spacing of pearlite and improves the strength of pearlite steel. Cr is an element that contributes to an increase in strength during wire drawing. Therefore, the Cr content may be 0% or more and 0.5% or less as necessary. The lower limit of the preferable Cr content is 0.1%. Moreover, when Cr content is 0.5% or less, since the fall of productivity resulting from pearlite transformation completion time becoming long can be suppressed, it is preferable.
V:0%以上0.50%以下
V(バナジウム)は、鋼中のCと結合してフェライト中に炭化物を析出させる元素である。この析出物がフェライトを硬化させる。したがって、必要に応じて、V含有量を0%以上0.5%以下としてもよい。好ましいV含有量の下限は0.005%である。また、V含有量が0.50%以下のとき、粗大な炭化物の生成に起因する加工時の割れを抑制できるので好ましい。 V: 0% or more and 0.50% or less V (Vanadium) is an element that combines with C in steel to precipitate carbide in ferrite. This precipitate hardens the ferrite. Therefore, the V content may be 0% or more and 0.5% or less as necessary. The lower limit of the preferred V content is 0.005%. Moreover, when V content is 0.50% or less, since the crack at the time of the process resulting from the production | generation of a coarse carbide | carbonized_material can be suppressed, it is preferable.
V(バナジウム)は、鋼中のCと結合してフェライト中に炭化物を析出させる元素である。この析出物がフェライトを硬化させる。したがって、必要に応じて、V含有量を0%以上0.5%以下としてもよい。好ましいV含有量の下限は0.005%である。また、V含有量が0.50%以下のとき、粗大な炭化物の生成に起因する加工時の割れを抑制できるので好ましい。 V: 0% or more and 0.50% or less V (Vanadium) is an element that combines with C in steel to precipitate carbide in ferrite. This precipitate hardens the ferrite. Therefore, the V content may be 0% or more and 0.5% or less as necessary. The lower limit of the preferred V content is 0.005%. Moreover, when V content is 0.50% or less, since the crack at the time of the process resulting from the production | generation of a coarse carbide | carbonized_material can be suppressed, it is preferable.
本実施形態に係る平鋼線1は、めっき層や被覆層を表面に有してもよい。以下、好ましいめっき層や被覆層について詳述する。
The flat steel wire 1 according to this embodiment may have a plating layer or a coating layer on the surface. Hereinafter, preferred plating layers and coating layers will be described in detail.
本実施形態に係る平鋼線1は、厚みが10μm以下であるZn又はNi含有めっき層を表面に有してもよい。このめっき層によって、平鋼線1の腐食を抑制できるので好ましく、また腐食による水素侵入や環境からの水素侵入などに起因する遅れ破壊を抑制できるので好ましい。また、めっき層の厚みが10μm以下のとき、二次加工時のめっき層の剥離を抑制できるので好ましい。
The flat steel wire 1 according to this embodiment may have a Zn or Ni-containing plating layer having a thickness of 10 μm or less on the surface. This plating layer is preferable because corrosion of the flat steel wire 1 can be suppressed, and delayed fracture due to hydrogen intrusion due to corrosion or hydrogen intrusion from the environment can be suppressed. Moreover, when the thickness of a plating layer is 10 micrometers or less, since peeling of the plating layer at the time of secondary processing can be suppressed, it is preferable.
また、本実施形態に係る平鋼線1は、防食効果を有する樹脂等の被覆層を表面に有してもよい。この被覆層によって、めっき層と同様の効果が得られる。
Further, the flat steel wire 1 according to the present embodiment may have a coating layer of a resin or the like having an anticorrosive effect on the surface. The effect similar to a plating layer is acquired by this coating layer.
以下、本実施形態に係る平鋼線1にとって重要な、引張特性、捻回特性、残留応力の測定方法について詳述する。
Hereinafter, a method for measuring tensile characteristics, twisting characteristics, and residual stress, which are important for the flat steel wire 1 according to the present embodiment, will be described in detail.
本実施形態に係る平鋼線1の引張特性は、JIS Z2241:2011、またはISO 6892-1:2009に準拠した引張試験によって求めればよい。引張試験結果から、降伏強度又は0.2%耐力、引張最大強度(引張強度)、及び破断伸びを求める。
The tensile properties of the flat steel wire 1 according to the present embodiment may be obtained by a tensile test based on JIS Z2241: 2011 or ISO 6892-1: 2009. From the tensile test results, yield strength or 0.2% proof stress, maximum tensile strength (tensile strength), and elongation at break are determined.
本実施形態に係る平鋼線1の捻回特性は、平刃チャックで両端をチャッキング後、片側を回転させる捻回試験によって求めればよい。その際、チャック間距離を500mmとし、捻回速度を10rpmとし、試験温度を室温とする条件で平鋼線1を捻回させる。そして、断線分離するまでの捻回回数を捻回値と定義する。
The twist characteristics of the flat steel wire 1 according to the present embodiment may be obtained by a twist test in which one end is rotated after chucking both ends with a flat blade chuck. At that time, the flat steel wire 1 is twisted under the conditions that the distance between chucks is 500 mm, the twisting speed is 10 rpm, and the test temperature is room temperature. The number of twists until disconnection is defined is defined as the twist value.
本実施形態に係る平鋼線1の表層部2の残留応力は、X線回折によって求めればよい。平鋼線1の長手方向に平行な面を測定面としてX線回折を行い、このX線回折結果を解析することによって、平鋼線1の表層部2の長手方向における残留応力を求めることができる。なお、複数箇所で表層部2の残留応力を測定し、これらの測定結果から残留応力の平均値を算出すればよい。具体的には、平鋼線1の長辺(幅)を4等分し、その等分点のうち両サイドを除いた3箇所を測定点とし、および短辺(厚み)を3等分し、その等分点のうち両サイドを除いた2箇所を測定点とすることが好ましい。そして、各測定点を各対辺側についても同じ方法で測定点を決定し、合計10点の測定点とすることが好ましい。この10点の測定点で、切断面に垂直な長手方向の残留応力を測定し、その平均値を平鋼線1の長手方向における残留応力とすることが好ましい。なお、平鋼線1の表層部2は、上記断面の輪郭線からこの断面の重心に向って深さが1μm以内となる領域と定義する。ターゲットはCrを用いて回折角を求める。試料面法線と結晶面法線とがなす角度φと、X線回折角度θとの関係をプロットして、その近似直線の傾きから残留応力を求める。
The residual stress of the surface layer portion 2 of the flat steel wire 1 according to this embodiment may be obtained by X-ray diffraction. It is possible to obtain the residual stress in the longitudinal direction of the surface layer portion 2 of the flat steel wire 1 by performing X-ray diffraction using a plane parallel to the longitudinal direction of the flat steel wire 1 and analyzing the X-ray diffraction result. it can. In addition, what is necessary is just to measure the residual stress of the surface layer part 2 in multiple places, and to calculate the average value of a residual stress from these measurement results. Specifically, the long side (width) of the flat steel wire 1 is divided into four equal parts, and three points excluding both sides of the equally divided points are used as measurement points, and the short side (thickness) is divided into three equal parts. Of the equally divided points, two points excluding both sides are preferably used as measurement points. And it is preferable to determine a measuring point by the same method also about each measuring point about each opposite side, and make it a total of 10 measuring points. It is preferable to measure the residual stress in the longitudinal direction perpendicular to the cut surface at these 10 measurement points and set the average value as the residual stress in the longitudinal direction of the flat steel wire 1. The surface layer portion 2 of the flat steel wire 1 is defined as a region having a depth of 1 μm or less from the contour line of the cross section toward the center of gravity of the cross section. The target uses Cr to determine the diffraction angle. The relationship between the angle φ formed by the sample surface normal and the crystal surface normal and the X-ray diffraction angle θ is plotted, and the residual stress is obtained from the slope of the approximate straight line.
以下、本実施形態に係る平鋼線1の製造方法について説明する。
Hereinafter, the manufacturing method of the flat steel wire 1 which concerns on this embodiment is demonstrated.
本実施形態に係る平鋼線1の製造方法は、特に限定されない。例えば、本実施形態に係る平鋼線1は、製鋼工程、鋳造工程、線材圧延工程、恒温変態工程、伸線工程などによって製造すればよい。また、必要に応じて、伸線工程後に、ショットブラスト工程や表面処理工程を有してもよい。
The manufacturing method of the flat steel wire 1 according to the present embodiment is not particularly limited. For example, the flat steel wire 1 according to the present embodiment may be manufactured by a steel making process, a casting process, a wire rod rolling process, a constant temperature transformation process, a wire drawing process, and the like. Moreover, you may have a shot blast process and a surface treatment process after a wire-drawing process as needed.
製鋼工程として、上記した基本元素、選択元素、及び不純物からなる溶鋼を得るために、製鋼することが好ましい。製鋼方法は特に限定されないが、原料として鉱石等を用いる高炉法、原料としてスクラップ等を用いる電炉法によって、溶鋼を製造すればよい。例えば、製鋼条件は、ΔT(過熱度)を15~20℃とすればよい。上記条件によって、平鋼線1の中心偏析を好ましく制御できる。
In the steelmaking process, it is preferable to make steel in order to obtain molten steel composed of the basic elements, selective elements, and impurities described above. Although the steelmaking method is not particularly limited, the molten steel may be produced by a blast furnace method using ore or the like as a raw material and an electric furnace method using scrap or the like as a raw material. For example, steelmaking conditions may be that ΔT (degree of superheat) is 15 to 20 ° C. By the said conditions, the center segregation of the flat steel wire 1 can be controlled preferably.
鋳造工程として、鋳片を得るために、製鋼工程後の溶鋼を鋳造することが好ましい。鋳造方法は特に限定されないが、真空鋳造法や連続鋳造法等を用いればよい。例えば、クレーターエンドの適正な圧下により凝固収縮時の濃厚偏析した溶鋼吸引を抑制することで、平鋼線1の中心偏析を好ましく制御できる。また、必要に応じて、鋳造工程後で線材圧延工程前の鋳片に、均熱拡散処理や熱間粗圧延(分塊圧延)等を施してもよい。
As the casting process, it is preferable to cast the molten steel after the steel making process in order to obtain a slab. The casting method is not particularly limited, but a vacuum casting method, a continuous casting method, or the like may be used. For example, the central segregation of the flat steel wire 1 can be preferably controlled by suppressing concentrated segregated molten steel suction during solidification shrinkage by appropriate reduction of the crater end. Moreover, you may give soaking | spreading diffusion process, hot rough rolling (bundling rolling) etc. to the slab after a casting process and before a wire-rolling process as needed.
線材圧延工程として、線材を得るために、鋳造工程後の鋳片を線材圧延することが好ましい。線材圧延条件は特に限定されないが、例えば、線材圧延開始温度を1050℃以上1150℃以下の温度範囲内とし、線材圧延終了温度を900℃以上1050℃以下の温度範囲内とし、線材圧延での累積圧下率を98.7%以上99.8℃%の範囲内とすればよい。上記条件によって、平鋼線1の中心偏析を好ましく制御できる。また、必要に応じて、線材圧延工程後で恒温変態工程前の線材を巻き取ってもよい。
As the wire rod rolling step, it is preferable to roll the slab after the casting step in order to obtain a wire rod. The wire rolling conditions are not particularly limited. For example, the wire rolling start temperature is set in a temperature range of 1050 ° C. or higher and 1150 ° C. or lower, the wire rolling end temperature is set in a temperature range of 900 ° C. or higher and 1050 ° C. or lower, and accumulation in wire rolling is performed. The rolling reduction may be in the range of 98.7% to 99.8%. By the said conditions, the center segregation of the flat steel wire 1 can be controlled preferably. Moreover, you may wind up the wire before a constant temperature transformation process after a wire rolling process as needed.
恒温変態(パテンティング)工程として、線材圧延工程後の線材を恒温変態温度に保持し、恒温変態処理後に線材を室温まで冷却することが好ましい。この際、線材圧延工程後の線材を室温まで冷却することなく恒温変態処理を直接行ってもよいし、または線材圧延工程後の線材を室温まで冷却した後に再加熱して恒温変態処理を行ってもよい。恒温変態条件は特に限定されないが、例えば、530℃以上550℃以下の温度範囲に保持された溶融ソルトに、60秒以上90秒以下の時間、線材を浸漬すればよい。上記条件によって、平鋼線1のパーライト組織を好ましく制御できる。本実施形態に係る平鋼線1は、金属組織として、パーライト組織を主に含む。なお、恒温変態処理中、線材の温度を完全に一定温度に制御する必要がなく、線材の温度が上記温度範囲内で変動してもよい。また、線材圧延工程後に恒温変態処理を直接行う場合、必要に応じて、線材圧延終了温度から恒温変態温度までの温度を、冷却速度12℃/秒以上30℃/秒以下の冷却速度となるように、線材を冷却してもよい。
As the constant temperature transformation (patenting) step, it is preferable to keep the wire after the wire rolling step at a constant temperature transformation temperature and to cool the wire to room temperature after the constant temperature transformation treatment. At this time, the wire rod after the wire rod rolling process may be directly subjected to the isothermal transformation treatment without cooling to room temperature, or the wire rod after the wire rod rolling step is cooled to room temperature and then reheated to perform the isothermal transformation treatment. Also good. The isothermal transformation condition is not particularly limited, but for example, the wire may be immersed in a molten salt maintained in a temperature range of 530 ° C. or higher and 550 ° C. or lower for a time of 60 seconds or longer and 90 seconds or shorter. Under the above conditions, the pearlite structure of the flat steel wire 1 can be preferably controlled. The flat steel wire 1 according to the present embodiment mainly includes a pearlite structure as a metal structure. In addition, it is not necessary to control the temperature of a wire to completely constant temperature during a constant temperature transformation process, and the temperature of a wire may fluctuate within the said temperature range. Moreover, when performing a constant temperature transformation process directly after a wire rod rolling process, as needed, the temperature from wire rod completion | finish temperature to a constant temperature transformation temperature is set to the cooling rate of 12 to 30 degree C / sec. In addition, the wire may be cooled.
伸線工程として、平鋼線1を得るために、恒温変態後の線材を伸線加工する。この際、平鋼線1を長手方向に垂直な断面で見た場合に、この断面の短辺が2mm以上7mm以下、この断面の長辺が8mm超56mm以下、短辺に対する前記長辺の比が4超8以下となるように、恒温変態後の線材を平鋼線1へ伸線加工する。伸線加工方法は、特に限定されないが、例えば、伸線ダイスによる伸線加工と平圧延とを組み合わせてもよい。具体的には、恒温変態後の線材を通常の伸線ダイスで伸線した後に、丸断面ダイス又は長方形断面ダイスによる伸線加工と、平圧延とを、必要に応じて組み合わせてもよい。
In the wire drawing process, in order to obtain the flat steel wire 1, the wire after the isothermal transformation is drawn. At this time, when the flat steel wire 1 is viewed in a cross section perpendicular to the longitudinal direction, the short side of the cross section is 2 mm or more and 7 mm or less, the long side of the cross section is more than 8 mm and 56 mm or less, and the ratio of the long side to the short side is The wire after the isothermal transformation is drawn into a flat steel wire 1 so that becomes more than 4 and 8 or less. Although the wire drawing method is not particularly limited, for example, wire drawing by a wire drawing die and flat rolling may be combined. Specifically, after drawing the wire after constant temperature transformation with a normal wire drawing die, wire drawing with a round cross-section die or a rectangular cross-section die and flat rolling may be combined as necessary.
本実施形態に係る平鋼線1は、伸線工程での加工量が大きいほど強度が上昇する。しかし、強度と二次加工性とを同時に満足するために、伸線工程での断面減少率を50%以上90%以下とすることが好ましい。ここで、伸線工程での断面減少率は、長手方向に垂直な断面を基準として、断面減少率=100-(伸線加工後の断面積)/(恒温変態処理後の断面積)×100と定義する。
The strength of the flat steel wire 1 according to this embodiment increases as the processing amount in the wire drawing process increases. However, in order to satisfy both the strength and the secondary workability at the same time, it is preferable that the cross-sectional reduction rate in the wire drawing step is 50% or more and 90% or less. Here, the cross-section reduction rate in the wire drawing step is based on the cross section perpendicular to the longitudinal direction: cross-section reduction rate = 100− (cross-sectional area after wire drawing) / (cross-sectional area after isothermal transformation treatment) × 100 It is defined as
必要に応じて、ショットブラスト工程として、伸線工程後の平鋼線1にショットブラストを施してもよい。ショットブラスト条件は特に限定されないが、例えば、ショットブラスト粒として無機系研磨材を用い、ショットブラスト粒径を340μm以上400μm以下とし、ショットブラスト圧を1kg/cm2以上3kg/cm2以下とし、ショットブラスト時間を10秒以上20秒以下とすればよい。具体的には、ショットブラスト粒径を370μmとし、ショットブラスト圧を2kg/cm2とし、ショットブラスト時間を15秒とすればよい。上記条件によって、平鋼線1の表層部2の長手方向における圧縮残留応力の平均値を-200MPa以下に制御できるので好ましい。
As needed, you may perform shot blasting to the flat steel wire 1 after a wire drawing process as a shot blasting process. The shot blasting conditions are not particularly limited. For example, an inorganic abrasive is used as shot blast particles, the shot blast particle size is set to 340 μm or more and 400 μm or less, the shot blast pressure is set to 1 kg / cm 2 or more and 3 kg / cm 2 or less, The blast time may be 10 seconds or more and 20 seconds or less. Specifically, the shot blast particle size may be 370 μm, the shot blast pressure may be 2 kg / cm 2 , and the shot blast time may be 15 seconds. The above conditions are preferable because the average value of the compressive residual stress in the longitudinal direction of the surface layer portion 2 of the flat steel wire 1 can be controlled to be −200 MPa or less.
必要に応じて、表面処理工程として、伸線工程後またはショットブラスト工程後の平鋼線1に表面処理を施してもよい。表面処理によって、平鋼線1にめっき層や被覆層を付与することが好ましい。表面処理条件は特に限定されなく、一般のめっき処理や表面被覆処理を施せばよい。
If necessary, as a surface treatment step, the flat steel wire 1 after the wire drawing step or the shot blasting step may be subjected to surface treatment. It is preferable to apply a plating layer or a coating layer to the flat steel wire 1 by surface treatment. The surface treatment conditions are not particularly limited, and general plating treatment or surface coating treatment may be performed.
実施例により本発明の一態様の効果を更に具体的に説明するが、実施例での条件は、本発明の実施可能性及び効果を確認するために採用した一条件例であり、本発明は、この一条件例に限定されない。本発明は、本発明の要旨を逸脱せず、本発明の目的を達成する限り、種々の条件を採用し得る。
The effects of one embodiment of the present invention will be described more specifically with reference to examples. However, the conditions in the examples are one example of conditions adopted to confirm the feasibility and effects of the present invention, and the present invention It is not limited to this one condition example. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.
(実施例)
表1~4に示す発明例No.1~18及び比較例No.19~30の平鋼線を作製した。平鋼線の金属組織は、線材圧延工程後の恒温変態工程で、微細なパーライト組織に調整した。また、強度を高めるため、伸線工程で、通常の伸線ダイスで途中まで伸線した後、丸断面ダイス又は長方形断面ダイスによる伸線加工と平圧延との少なくとも1つ行って成形加工した。また、必要に応じて、ショットブラスト工程として、平鋼線にショットブラストを施した。ショットブラスト粒として無機系研磨材を用い、ショットブラスト粒径を340μm以上400μm以下とし、ショットブラスト圧を1kg/cm2以上3kg/cm2以下とし、ショットブラスト時間を10秒以上20秒以下の条件で、平鋼線にショットブラストを施した。 (Example)
Invention Example Nos. Shown in Tables 1 to 4 1 to 18 and Comparative Example No. 19 to 30 flat steel wires were produced. The metal structure of the flat steel wire was adjusted to a fine pearlite structure in the constant temperature transformation process after the wire rod rolling process. Further, in order to increase the strength, in the wire drawing step, the wire was drawn halfway with a normal wire drawing die, and then formed by performing at least one of wire drawing using a round cross-section die or a rectangular cross-section die and flat rolling. Moreover, if necessary, shot blasting was performed on a flat steel wire as a shot blasting process. An inorganic abrasive is used as the shot blast grain, the shot blast particle size is 340 μm or more and 400 μm or less, the shot blast pressure is 1 kg / cm 2 or more and 3 kg / cm 2 or less, and the shot blasting time is 10 seconds or more and 20 seconds or less. Then, shot blasting was applied to the flat steel wire.
表1~4に示す発明例No.1~18及び比較例No.19~30の平鋼線を作製した。平鋼線の金属組織は、線材圧延工程後の恒温変態工程で、微細なパーライト組織に調整した。また、強度を高めるため、伸線工程で、通常の伸線ダイスで途中まで伸線した後、丸断面ダイス又は長方形断面ダイスによる伸線加工と平圧延との少なくとも1つ行って成形加工した。また、必要に応じて、ショットブラスト工程として、平鋼線にショットブラストを施した。ショットブラスト粒として無機系研磨材を用い、ショットブラスト粒径を340μm以上400μm以下とし、ショットブラスト圧を1kg/cm2以上3kg/cm2以下とし、ショットブラスト時間を10秒以上20秒以下の条件で、平鋼線にショットブラストを施した。 (Example)
Invention Example Nos. Shown in Tables 1 to 4 1 to 18 and Comparative Example No. 19 to 30 flat steel wires were produced. The metal structure of the flat steel wire was adjusted to a fine pearlite structure in the constant temperature transformation process after the wire rod rolling process. Further, in order to increase the strength, in the wire drawing step, the wire was drawn halfway with a normal wire drawing die, and then formed by performing at least one of wire drawing using a round cross-section die or a rectangular cross-section die and flat rolling. Moreover, if necessary, shot blasting was performed on a flat steel wire as a shot blasting process. An inorganic abrasive is used as the shot blast grain, the shot blast particle size is 340 μm or more and 400 μm or less, the shot blast pressure is 1 kg / cm 2 or more and 3 kg / cm 2 or less, and the shot blasting time is 10 seconds or more and 20 seconds or less. Then, shot blasting was applied to the flat steel wire.
そして、発明例及び比較例について、引張特性、捻回特性、残留応力の測定を行った。
And about the invention example and the comparative example, the tensile characteristic, the twist characteristic, and the residual stress were measured.
引張特性は、JIS Z2241:2011、またはISO 6892-1:2009に準拠した引張試験を行って測定した。引張試験結果から、降伏強度又は0.2%耐力、引張最大強度(引張強度)、及び破断伸びを求めた。
Tensile properties were measured by performing a tensile test based on JIS Z2241: 2011 or ISO 6892-1: 2009. From the tensile test results, yield strength or 0.2% yield strength, tensile maximum strength (tensile strength), and elongation at break were determined.
捻回特性は、平刃チャックで両端をチャッキング後、片側を回転させる捻回試験を行って測定した。その際、チャック間距離を500mmとし、捻回速度を10rpmとし、試験温度を室温とする条件で平鋼線を捻回させた。そして、断線分離するまでの捻回回数を捻回値とした。
The twisting property was measured by performing a twisting test in which one side was rotated after chucking both ends with a flat blade chuck. At that time, the flat steel wire was twisted under the conditions that the distance between chucks was 500 mm, the twisting speed was 10 rpm, and the test temperature was room temperature. Then, the number of twists until disconnection and separation was taken as the twist value.
残留応力は、平鋼線の表層部について、X線回折結果を解析することによって求めた。具体的には、平鋼線の長辺(幅)を4等分し、その等分点のうち両サイドを除いた3箇所を測定点とし、および短辺(厚み)を3等分し、その等分点のうち両サイドを除いた2箇所を測定点とした。各測定点を各対辺側についても同じ方法で測定点を決定し、合計10点の測定点でX線回折を行った。これらのX線回折結果を解析することによって、切断面に垂直な長手方向の残留応力の平均値を求めた。ターゲットとしてCrを用い、試料面法線と結晶面法線とがなす角度φと、X線回折角度θとの関係をプロットして、その近似直線の傾きから残留応力を求めた。
Residual stress was determined by analyzing the X-ray diffraction results for the surface layer portion of the flat steel wire. Specifically, the long side (width) of the flat steel wire is divided into four equal parts, and the three points excluding both sides of the equally divided points are used as measurement points, and the short side (thickness) is divided into three equal parts, Two points of the equally divided points excluding both sides were taken as measurement points. The measurement points were determined by the same method for each opposite side, and X-ray diffraction was performed at a total of 10 measurement points. By analyzing these X-ray diffraction results, the average value of the residual stress in the longitudinal direction perpendicular to the cut surface was determined. Using Cr as a target, the relationship between the angle φ formed by the sample surface normal and the crystal surface normal and the X-ray diffraction angle θ was plotted, and the residual stress was obtained from the slope of the approximate straight line.
これらの測定結果を、表1~4に併せて示す。なお、表中、下線で示す数値は、本発明の範囲外であることを示す。また表中、化学成分に関して「―」は、意図的に添加していないか、または検出限界以下の値であることを示す。実施例1~18は、長手方向に垂直な断面で見た場合の長辺(幅)、短辺(厚み)、及び幅/厚み比(短辺に対する長辺の比)が本発明の範囲を満足し、引張特性及び捻回特性も本発明の範囲を満足した。
These measurement results are also shown in Tables 1 to 4. In addition, the numerical value shown with an underline in a table | surface shows that it is outside the range of this invention. Further, in the table, “-” for a chemical component indicates that it is not intentionally added or is a value below the detection limit. In Examples 1 to 18, the long side (width), short side (thickness), and width / thickness ratio (ratio of long side to short side) when viewed in a cross section perpendicular to the longitudinal direction are within the scope of the present invention. Satisfactory, tensile properties and twisting properties also satisfied the scope of the present invention.
一方、比較例19~30は、長辺(幅)、短辺(厚み)、幅/厚み比(短辺に対する長辺の比)、捻回特性のいずれかが不十分となっていた。
On the other hand, in Comparative Examples 19 to 30, any of the long side (width), the short side (thickness), the width / thickness ratio (ratio of the long side to the short side), and the twisting property was insufficient.
本発明の上記態様によれば、平鋼線の形状などが好ましく制御されるので、例えば捻回加工時に、平鋼線の外周面からの割れの発生と、その進展による平鋼線の縦割れなどが抑制される。その結果、従来の高強度平鋼線と比較して、高い二次加工性を有する高強度平鋼線を得ることが可能である。よって、産業上の利用可能性が高い。
According to the above aspect of the present invention, since the shape of the flat steel wire and the like is preferably controlled, for example, during the twisting process, the occurrence of cracks from the outer peripheral surface of the flat steel wire and the vertical crack of the flat steel wire due to its progress Etc. are suppressed. As a result, it is possible to obtain a high-strength flat steel wire having high secondary workability as compared with conventional high-strength flat steel wires. Therefore, industrial applicability is high.
1 平鋼線
2 表層部 1Flat steel wire 2 Surface layer
2 表層部 1
Claims (7)
- 長手方向に垂直な断面で見た場合に角丸矩形である平鋼線であって、
前記断面の短辺が2mm以上7mm以下、
前記断面の長辺が8mm超56mm以下、
前記短辺に対する前記長辺の比が4超8以下であり、
引張試験で得られる降伏強度又は0.2%耐力が1600MPa以上2000MPa以下、引張強度が1900MPa以上、破断伸びが2%以上であり、
チャック間距離を500mmとする条件での捻回試験で得られる捻回値が12回以上である
ことを特徴とする平鋼線。 A flat steel wire that is a rounded rectangle when viewed in a cross section perpendicular to the longitudinal direction,
The short side of the cross section is 2 mm or more and 7 mm or less,
The long side of the cross section is more than 8 mm and 56 mm or less,
The ratio of the long side to the short side is more than 4 and 8 or less,
Yield strength or 0.2% yield strength obtained by a tensile test is 1600 MPa or more and 2000 MPa or less, tensile strength is 1900 MPa or more, and elongation at break is 2% or more,
A flat steel wire characterized in that a twist value obtained by a twist test under a condition that the distance between chucks is 500 mm is 12 times or more. - 前記断面で見た場合に、前記断面の輪郭線から前記断面の重心に向って深さが1μm以内となる領域を前記平鋼線の表層部としたとき、
前記表層部で、前記長手方向における圧縮残留応力の平均値が-200MPa以下である
ことを特徴とする請求項1に記載の平鋼線。 When viewed in the cross-section, when the area of the flat steel wire is a surface layer portion having a depth of 1 μm or less from the outline of the cross-section toward the center of gravity of the cross-section,
The flat steel wire according to claim 1, wherein, in the surface layer portion, an average value of compressive residual stress in the longitudinal direction is -200 MPa or less. - 前記平鋼線の化学成分が、質量%で、
C :0.85%以上1.00%以下、
Si:0.80%以上1.30%以下、
Mn:0.30%以上0.90%以下、
P :0.017%以下、
S :0.010%以下、
Cu:0.20%以下、
Al:0%以上0.10%以下、
Ti:0%以上0.05%以下、
B :0%以上0.0040%以下、
N :0%以上0.0060%以下、
Cr:0%以上0.5%以下、
V :0%以上0.50%以下
を含有し、
残部がFe及び不純物からなる
ことを特徴とする請求項1又2に記載の平鋼線。 The chemical composition of the flat steel wire is mass%,
C: 0.85% or more and 1.00% or less,
Si: 0.80% or more and 1.30% or less,
Mn: 0.30% or more and 0.90% or less,
P: 0.017% or less,
S: 0.010% or less,
Cu: 0.20% or less,
Al: 0% or more and 0.10% or less,
Ti: 0% or more and 0.05% or less,
B: 0% or more and 0.0040% or less,
N: 0% or more and 0.0060% or less,
Cr: 0% to 0.5%,
V: 0% or more and 0.50% or less
The flat steel wire according to claim 1 or 2, wherein the balance consists of Fe and impurities. - 前記平鋼線の前記化学成分が、質量%で、
Al:0.005%以上0.10%以下、
Ti:0.003%以上0.05%以下、
B :0.0005%以上0.0040%以下、
N :0.0015%以上0.0060%以下
のうちの少なくとも1つを含有する
ことを特徴とする請求項1~3のいずれか1項に記載の平鋼線。 The chemical component of the flat steel wire is mass%,
Al: 0.005% or more and 0.10% or less,
Ti: 0.003% to 0.05%,
B: 0.0005% or more and 0.0040% or less,
The flat steel wire according to any one of claims 1 to 3, comprising at least one of N: 0.0015% to 0.0060%. - 前記平鋼線の前記化学成分が、質量%で、
Cr:0.1%以上0.5%以下、
V :0.005%以上0.50%以下
のうちの少なくとも1つを含有する
ことを特徴とする請求項1~4のいずれか1項に記載の平鋼線。 The chemical component of the flat steel wire is mass%,
Cr: 0.1% to 0.5%,
The flat steel wire according to any one of claims 1 to 4, comprising at least one of V: 0.005% to 0.50%. - 前記断面の前記短辺が2mm以上6mm以下、
前記断面の前記長辺が8mm超48mm以下、
であることを特徴とする請求項1~5のいずれか1項に記載の平鋼線。 The short side of the cross section is 2 mm or more and 6 mm or less,
The long side of the cross section is more than 8 mm and 48 mm or less,
The flat steel wire according to any one of claims 1 to 5, wherein: - 前記断面の前記短辺が2mm以上5mm以下、
前記断面の前記長辺が8mm超40mm以下、
であることを特徴とする請求項6に記載の平鋼線。 The short side of the cross section is 2 mm or more and 5 mm or less,
The long side of the cross section is more than 8 mm and 40 mm or less,
The flat steel wire according to claim 6, wherein:
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
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DK14791514.4T DK2993246T3 (en) | 2013-04-30 | 2014-04-22 | FLAT STEEL WIRE |
JP2015514815A JP6116680B2 (en) | 2013-04-30 | 2014-04-22 | Flat steel wire |
EP14791514.4A EP2993246B1 (en) | 2013-04-30 | 2014-04-22 | Flat steel wire |
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JP2013095774 | 2013-04-30 | ||
JP2013-095774 | 2013-04-30 |
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WO2014178303A1 true WO2014178303A1 (en) | 2014-11-06 |
Family
ID=51843437
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/JP2014/061228 WO2014178303A1 (en) | 2013-04-30 | 2014-04-22 | Flat steel wire |
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Country | Link |
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EP (1) | EP2993246B1 (en) |
JP (1) | JP6116680B2 (en) |
DK (1) | DK2993246T3 (en) |
WO (1) | WO2014178303A1 (en) |
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SE545660C2 (en) * | 2021-10-28 | 2023-11-28 | Suzuki Garphyttan Ab | Flat wire and method for production thereof |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS63145713A (en) * | 1986-12-09 | 1988-06-17 | Nippon Steel Corp | Production of high-strength steel wire having excellent hydrogen induced cracking resistance characteristic |
JPH042720A (en) * | 1990-04-19 | 1992-01-07 | Nippon Steel Corp | Production of high strength steel wire for use in sour environment |
JPH06235024A (en) * | 1993-02-09 | 1994-08-23 | Nippon Steel Corp | Production of high strength deformed steel wire |
JP2002309347A (en) * | 2001-04-13 | 2002-10-23 | Nippon Steel Corp | Flat wire and metal sheet and rubber product using the flat wire |
JP2010229469A (en) * | 2009-03-26 | 2010-10-14 | Nippon Steel Corp | High-strength wire rod excellent in cold working characteristic and method of producing the same |
JP2010229468A (en) * | 2009-03-26 | 2010-10-14 | Nippon Steel Corp | High-strength flat steel wire |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1713946A1 (en) * | 2004-02-13 | 2006-10-25 | NV Bekaert SA | Steel wire with metal layer and roughnesses |
TWI412608B (en) * | 2009-06-22 | 2013-10-21 | Nippon Steel & Sumitomo Metal Corp | High strength extra-fine steel wire and manufacturing method thereof |
-
2014
- 2014-04-22 WO PCT/JP2014/061228 patent/WO2014178303A1/en active Application Filing
- 2014-04-22 EP EP14791514.4A patent/EP2993246B1/en not_active Not-in-force
- 2014-04-22 JP JP2015514815A patent/JP6116680B2/en active Active
- 2014-04-22 DK DK14791514.4T patent/DK2993246T3/en active
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS63145713A (en) * | 1986-12-09 | 1988-06-17 | Nippon Steel Corp | Production of high-strength steel wire having excellent hydrogen induced cracking resistance characteristic |
JPH042720A (en) * | 1990-04-19 | 1992-01-07 | Nippon Steel Corp | Production of high strength steel wire for use in sour environment |
JPH06235024A (en) * | 1993-02-09 | 1994-08-23 | Nippon Steel Corp | Production of high strength deformed steel wire |
JP3298688B2 (en) | 1993-02-09 | 2002-07-02 | 新日本製鐵株式会社 | Manufacturing method of high strength deformed steel wire |
JP2002309347A (en) * | 2001-04-13 | 2002-10-23 | Nippon Steel Corp | Flat wire and metal sheet and rubber product using the flat wire |
JP2010229469A (en) * | 2009-03-26 | 2010-10-14 | Nippon Steel Corp | High-strength wire rod excellent in cold working characteristic and method of producing the same |
JP2010229468A (en) * | 2009-03-26 | 2010-10-14 | Nippon Steel Corp | High-strength flat steel wire |
Also Published As
Publication number | Publication date |
---|---|
EP2993246B1 (en) | 2019-03-20 |
JPWO2014178303A1 (en) | 2017-02-23 |
DK2993246T3 (en) | 2019-05-13 |
JP6116680B2 (en) | 2017-04-19 |
EP2993246A1 (en) | 2016-03-09 |
EP2993246A4 (en) | 2017-01-04 |
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