WO2018043491A1 - 圧延h形鋼及びその製造方法 - Google Patents
圧延h形鋼及びその製造方法 Download PDFInfo
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
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- B21B1/08—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling structural sections, i.e. work of special cross-section, e.g. angle steel
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- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
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- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
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- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
- B21B27/02—Shape or construction of rolls
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- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
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- 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
- C21D6/00—Heat treatment of ferrous alloys
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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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- 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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
Definitions
- the present invention relates to a rolled H-section steel produced by hot rolling a steel slab and a method for producing the same.
- H-section steel has been widely used as a material for buildings, civil engineering, marine structures, etc., and various cross-sections are used.
- H-section steel produced by hot rolling using a rectangular cross-section slab obtained by continuous casting with high productivity is low in production cost and is used in many fields.
- H-section steel manufactured from a slab has been manufactured by the edging method shown in FIG.
- the edging method first, a groove for guiding the steel material to the center of the hole mold of the roll is formed at the end of the slab, rolled in the width direction of the slab, and the flange is formed by extending the end of the slab in the thickness direction of the slab. It is a rolling method.
- Alloy elements such as Mn are concentrated in the central segregation portion formed when the slab is cast.
- the central segregation portion may further aggregate at a portion where the web and the flange intersect, that is, a so-called “fillet portion”, which may adversely affect toughness.
- Patent Document 4 discloses a method of applying a reduction before completely solidifying by continuous casting.
- Patent Document 5 discloses a method of forming an edging hole mold having a slab width of a rough rolling mill into a box hole mold having a flat hole mold bottom, and is referred to as a wedge method.
- JP 2012-180584 A Japanese Patent Laid-Open No. 6-122921 JP-A-6-122922 JP-A-5-305395 JP-A-7-88502
- an object of the present invention is to provide a rolled H-section steel in which macrosegregation of the fillet portion is reduced and a method for producing the same without impairing productivity with respect to the conventional edging method.
- the present invention is characterized in that there is a step of forming an interruption by a shaping hole mold in which a projecting portion for making an interruption vertically is formed with respect to the width direction of the material to be rolled, and sequentially bending it from the starting point.
- a center segregation part is disperse
- the gist of the present invention is as follows.
- a rolled H-section steel having a Mn concentration of 1.1 to 1.6 times the Mn concentration at a 1/4 position in the flange thickness direction from the surface of the flange opposite to the web is a position of 1/6 in the flange width direction from the end face in the flange width direction, and A rolled H-section steel having a Mn concentration of 1.1 to 1.6 times the Mn concentration at a 1/4 position in the flange thickness direction from the surface of the flange opposite to the web.
- the rolling mill that performs the rough rolling process is provided with a plurality of three or more hole molds for shaping the material to be rolled, and at least one of the plurality of hole molds interrupts perpendicularly to the width direction of the material to be rolled.
- the interrupt forming hole type provided on the pair of upper and lower rolls formed with the projections for inserting the interrupting part, and the divided portions formed by the interrupt forming hole type are sequentially bent at the subsequent stage of the interrupt forming hole type.
- a method for producing a rolled H-section steel, wherein a shaping hole mold is provided. [3] The method for producing rolled H-section steel according to [2], wherein a tip angle of the protrusion formed in the interrupt forming hole mold is 40 ° or less.
- the interruption length H formed by the protrusions, the thickness T of the steel piece having the rectangular cross section, and the width F of the flange of the rolled H-section steel formed by the finish rolling process are as follows: The method for producing a rolled H-section steel according to [2] or [3], wherein the formula (1) is satisfied. H ⁇ 0.5F-0.5T (1)
- the present invention it is possible to obtain an H-section steel having excellent fillet portion toughness by a simple process without performing special heat treatment such as preheating, reheating after rolling, or temperature maintenance. Therefore, the industrial contribution of the present invention is extremely remarkable, such as the reliability of the steel structure including the rolled H-section steel as a member can be further improved without impairing the economy.
- the inventors have obtained the knowledge that, when forming the flange portion, interrupting and bending and manufacturing the flange portion, segregation is dispersed throughout the flange and segregation of segregation in the fillet portion is improved. .
- this knowledge will be briefly described.
- molding by bending the flange part which concerns on this Embodiment is called a "split method" in this specification.
- FIG. 1 shows a so-called “edging method” which is one of rough rolling methods in a conventional method for manufacturing H-section steel, and a so-called “split method” which is a rough rolling method in the method for manufacturing H-shaped steel according to the present embodiment. It is a schematic explanatory drawing about a comparison with ".”
- the edging method provides a groove for guiding the slab to the center of the hole mold at the end of the slab at the time of rough rolling when manufacturing the H-section steel from the slab.
- hot rolling is performed by a perforated roll attached to a machine.
- the slab heated in the heating furnace is rolled in the width direction, and the flange portion is formed by extending the end of the slab in the thickness direction of the slab.
- intermediate rolling by an intermediate rolling mill or finish rolling by a finishing mill is performed, and the final H Shaped steel products are manufactured.
- a deep groove is formed on the end surface of the slab at the time of rough rolling when manufacturing H-section steel from the slab. It is given by the hole type. Then, rolling modeling is performed on the applied groove so as to split the slab end portion which is a divided portion by using a hole roll of a modeling hole type in which a protrusion for expanding the groove is formed. Is called.
- the split method is a method of forming the flange portion by performing such split rolling and shaping, for example, by changing the angle a plurality of times. Thus, intermediate rolling, finish rolling, etc. are further performed with respect to the to-be-rolled material in which the flange part was formed, and final H-section steel products are manufactured.
- the present inventors pay attention to the central segregation part, which is a portion having a high Mn concentration, present in the slab, and the rough rolling by the edging method and the split method.
- the central segregation part which is a portion having a high Mn concentration, present in the slab
- the rough rolling it was found that there is a great difference in the state of aggregation or dispersion of the central segregation part of the slab. That is, as shown in FIG. 1 (a), it is known that the center segregation part aggregates into the fillet part when the slab is rolled in the width direction by the perforated roll in the edging method.
- FIG. 1 (a) it is known that the center segregation part aggregates into the fillet part when the slab is rolled in the width direction by the perforated roll in the edging method.
- FIG. 1 (a) it is known that the center segregation part aggregates into the fillet part when the slab is rolled in the width direction by the perforated roll
- the slab in the split method, the slab is hardly rolled in the width direction and the flange portion is split and the center segregation portion is dispersed throughout the flange portion, and the fillet portion is dispersed. Rough rolling is performed without agglomeration.
- the aggregation of the central segregation portion can be suppressed by setting the tip end angle of the interrupting hole-type protrusion to an acute angle of 40 ° or less.
- VTrs Charge transition temperature
- F / 6 F / 6
- FIG. 10 It has been found that the difference in vTrs with the most brittle part where the toughness is most deteriorated can be suppressed within 40 ° C. This is presumably because embrittlement due to MnS present in the central segregation part having a high Mn concentration, island-like martensite (MA) which is a hard phase, and upper bainite was suppressed.
- MA island-like martensite
- C 0.01-0.25%) C promotes the formation of MA at the fillet portion and reduces toughness.
- the C content is set to 0.01% or more.
- the amount of C exceeds 0.25%, MA increases at the position where the central segregation portion of the fillet portion is aggregated and the toughness is lowered, so the amount of C is limited to 0.25% or less.
- the C content is 0.20% or less, more preferably less than 0.17%.
- Si 0.05 to 0.50% or less
- Si is a deoxidizing element and contributes to improvement in strength, but like C, it is an element that generates MA.
- the amount of Si is preferably 0.30% or less, more preferably 0.20% or less, and still more preferably 0.10% or less.
- Si is not contained, the cost increases in the deoxidation process, so that Si is contained in an amount of 0.05% or more.
- Mn 0.40 to 2.50%
- Mn the center segregation part of the slab is aggregated in the fillet part.
- Mn tends to agglomerate particularly in the central segregation part, and the concentration of Mn locally increases to form MA as an embrittled phase, increase in coarse bainite as a coarse structure, increase in MnS, and increase in hardenability. Increase in hardness is promoted.
- the toughness is significantly reduced.
- Mn when Mn exceeding 2.50% is contained, the toughness of the base material and the weld heat affected zone is impaired due to an increase in inclusions in the fillet portion.
- the amount of Mn is limited to 2.50% or less.
- the amount of Mn is preferably 2.00% or less, more preferably 1.80% or less.
- Mn is an element effective for reducing the crystal grain size, 0.40% or more is contained.
- P 0.050% or less Since P causes weld cracking due to solidification segregation and a decrease in toughness, it should be reduced as much as possible.
- the amount of P is preferably limited to 0.050% or less, more preferably 0.010% or less. In addition, about a lower limit, since it will raise steel-making cost large if it removes to less than 0.001%, 0.001% or more may be sufficient.
- S forms MnS in the central segregation part formed by solidification segregation, and causes not only weld cracking and toughness degradation but also hydrogen cracking, so it should be reduced as much as possible.
- the amount of S is preferably limited to 0.050% or less, and more preferably 0.010% or less. In addition, about a lower limit, since it will raise steel-making cost large if it removes to less than 0.001%, 0.001% or more may be sufficient.
- one or more of Cu, Ni, Cr, V, Mo, Nb, Ti, Al, and N may be contained as an optional additive element.
- the lower limit of the content of each optional addition element is 0%.
- Cu is an element that contributes to improvement in strength. However, if the Cu content exceeds 0.70%, the strength increases excessively and the toughness decreases, so the Cu content is limited to 0.70% or less.
- the Cu amount is preferably 0.50% or less, more preferably 0.30% or less, and still more preferably 0.10% or less.
- the lower limit of the amount of Cu is preferably 0.01%.
- Ni is an extremely effective element for increasing strength and toughness.
- Ni is an expensive element, and in order to suppress an increase in alloy cost, the amount of Ni is limited to 0.70% or less, preferably 0.50% or less, more preferably 0.30% or less, and still more preferably. Is 0.10% or less.
- the Ni content is preferably 0.01% or more, more preferably 0.02% or more.
- Cr 0.50% or less
- Cr is also an element contributing to the improvement of strength. However, if Cr is added in excess of 0.50%, carbides may be generated and the toughness may be impaired. Therefore, the Cr content is limited to 0.50% or less, preferably 0.30% or less. The lower limit of the Cr amount is preferably 0.01%.
- V is an element forming nitride (VN), and may be contained in an amount of 0.01% or more in order to increase the strength of the base material.
- the V amount is 0.02% or more, more preferably 0.03% or more.
- the upper limit of the amount of V is limited to 0.12%, preferably 0.08%.
- Mo is an element that enhances hardenability and contributes to improvement in strength. However, if Mo is added exceeding 0.30%, precipitation of Mo carbide (Mo 2 C) and generation of MA in the fillet portion are promoted, and in particular, the toughness of the weld heat affected zone may be deteriorated.
- the amount is limited to 0.30% or less, preferably 0.15% or less.
- the lower limit of the Mo amount is preferably 0.01%.
- Nb 0.08% or less
- Nb is an element that refines ferrite and improves toughness. However, if added over 0.08%, ferrite transformation is excessively suppressed and the formation of MA is promoted, so the amount of Nb is limited to 0.08% or less, preferably 0.05% or less, more preferably 0.03% or less.
- Ti is an element that forms TiN.
- Ti content exceeds 0.05%, TiN becomes coarse and becomes the starting point of brittle fracture, so the Ti content is limited to 0.05% or less.
- the Ti content is 0.03% or less, more preferably 0.02% or less.
- the lower limit of the amount of Ti may be 0%, but fine TiN contributes to the refinement of the structure, so 0.005% or more may be contained.
- Al is a deoxidizing element, but if the Al content exceeds 0.07%, the toughness of the base metal and the weld heat affected zone is lowered by inclusions, so the Al content is limited to 0.07% or less.
- the Al content is preferably 0.05% or less, more preferably 0.04% or less, and still more preferably 0.03% or less.
- the lower limit of the amount of Al is not specified and may be 0%, but Al is a useful deoxidizing element and may contain 0.01% or more.
- N is an element that lowers the toughness of the base material and the weld heat affected zone. If the N content exceeds 0.020%, the low temperature toughness is impaired by the formation of solid solution N or coarse precipitates, so the N content is limited to 0.020% or less.
- the N amount is preferably 0.010% or less, more preferably 0.007% or less. On the other hand, if it is attempted to reduce the N content to less than 0.002%, the steelmaking cost increases, so the N content may be 0.002% or more. From the viewpoint of cost, the N amount may be 0.003% or more.
- one or two of REM and Ca may be added as optional additional elements.
- REM 0.010% or less, Ca: 0.0050% or less
- REM and Ca are deoxidizing elements and contribute to control of the form of sulfide, they may be added.
- the amount of REM contained in the steel is limited to 0.010% or less and the amount of Ca is limited to 0.0050% or less.
- the lower limits of the REM amount and the Ca amount are each 0.0005%.
- FIG. 3 is a schematic explanatory view showing a position where the mechanical test and the observation of the metal structure are performed. Below, the result of having verified about a metal structure
- the flange width direction end face of the flange is 1/6 in the flange width direction, and the flange face located on the opposite side of the web (ie, the outer face) is 1/4 in the flange thickness direction.
- the position of is in the middle between the flange end portion where the temperature tends to decrease during hot rolling and the flange center portion where the temperature does not easily decrease. Further, the central segregation part is not observed at this site. Therefore, this position is considered to show the average chemical composition and mechanical properties of the H-section steel from the temperature distribution. In this specification, the position is expressed as “F / 6-t / 4” using the flange width F and the flange thickness t.
- the H-section steel according to this embodiment suppresses material variations in the flange. Therefore, the observation of the metal structure of the H-section steel and the measurement of mechanical properties (strength and Charpy absorbed energy) were carried out with the most brittle part in the vicinity of F / 2-3t / 4 of the H-section steel shown in FIG. Sample pieces are collected from each position of / 6-t / 4.
- the position of the most brittle part is not constant with respect to the horizontal direction of the figure, that is, the flange width direction, depending on the situation during rough flange rolling. Therefore, after the portion where the central segregation portion is agglomerated is revealed by the nital corrosion liquid, the position of 3/4 (3t / 4) is indicated in the flange thickness direction from the surface of the flange opposite to the web. The portion where the straight line and the portion where the central segregation portion agglomerates intersects was determined as the position of the most brittle portion. A sample piece was taken from the most embrittled portion whose position was specified, and the metal structure was observed and the mechanical properties were measured.
- the metal structure of the rolled H-section steel of the present invention is evaluated by an optical microscope, a scanning electron microscope (SEM), and an electron beam microanalyzer (EPMA).
- SEM scanning electron microscope
- EPMA electron beam microanalyzer
- a 10 mm ⁇ 10 mm visual field centered on the most brittle portion shown in FIG. 3 is identified by an optical microscope.
- the Mn concentration at the position of the most embrittled portion determined was measured under the conditions of an acceleration voltage of 20 kV after electropolishing, a beam shape of a 20 ⁇ m long strip, and a step of 20 ⁇ m.
- an average value of 12500 points which is the value of the top 5% or more (referred to as “the top 5% average value”), is obtained, and the Mn concentration at the most brittle part ( CMn-max) It was.
- a sample was taken from the position of F / 6-t / 4, and according to JIS G0404 (2014 version), the chemical component of the sample was analyzed to obtain the value of Mn concentration at the position of F / 6-t / 4.
- Mn concentration (CMn) in Further, the value (CMn-max) / (CMn) obtained by dividing (CMn-max) by (CMn) was evaluated as the degree of segregation.
- the target value of the strength of the rolled H-section steel according to the present invention was set based on the steel standard EN10225 adopted in Europe. Yield point (YP) or 0.2% proof stress measured at room temperature is 325 MPa or more and tensile strength (TS) is 450 MPa or more using a sample piece taken from the position of F / 6-t / 4. Is desirable.
- the target value of toughness is set to ⁇ vTrs ⁇ 40 ° C.
- FIG. 2 is a diagram showing a correlation between the segregation degree and the Charpy transition temperature difference ⁇ vTrs in the H-section steel.
- the segregation degree in FIG. 2 is the concentration ratio of Mn at the most brittle portion and the position of F / 6-t / 4 described above with reference to FIG.
- the segregation degree exceeds 1.6, the most brittle part, and the position of F / 6-t / 4 And the Charpy transition temperature difference ⁇ vTrs with respect to.
- the rolled H-section steel manufactured by the split method has a Charpy transition temperature difference ⁇ vTrs of 40 ° C. or less between the most brittle portion and the position of F / 6 ⁇ t / 4. That is, in a state where the segregation degree is 1.6 or less, aggregation of the center segregation portion is suppressed, and a rolled H-section steel having excellent uniformity in the cross section of the flange as compared with the conventional product can be obtained.
- the segregation degree shown in FIG. 2 is preferably 1.6 or less. Furthermore, the lower the degree of segregation, the more the aggregation of the central segregation part is suppressed and the embrittlement characteristics are improved. Further, the degree of segregation does not fall below 1.0 in terms of numerical characteristics, and is preferably 1.0 or more or 1.1 or more, for example.
- the chemical composition of the molten steel is adjusted and then cast to obtain a rectangular steel piece (also called “slab”).
- the casting is preferably continuous casting from the viewpoint of productivity.
- the thickness of the steel slab is preferably 200 mm or more from the viewpoint of productivity, and is preferably 350 mm or less in consideration of reduction of segregation, uniformity of heating temperature in hot rolling, and the like.
- the steel slab is heated using a heating furnace and hot rolled.
- rough rolling is performed by the split method shown in FIG.
- intermediate rolling is performed using an intermediate universal rolling mill (intermediate rolling mill) and a water cooling device.
- finish rolling is performed using a finish rolling mill and hot rolling is finished.
- the H-section steel may be water-cooled at a timing as required.
- Heating temperature of steel slab 1100 to 1350 ° C
- the heating temperature of the steel slab is 1100 to 1350 ° C.
- the heating temperature is set to 1100 ° C. or higher in order to ensure the formability in hot rolling.
- the heating temperature of the steel slab exceeds 1350 ° C., the oxide on the surface of the steel slab, which is the raw material, may melt and the inside of the heating furnace may be damaged.
- the lower limit of the heating temperature of the steel slab is preferably set to 1150 ° C. or higher.
- the heating temperature of the steel slab is 1200 ° C. or higher.
- the upper limit of the heating temperature of the steel slab is 1300 ° C. or less.
- the thickness T of the steel piece having a rectangular cross section and the width F of the flange of the rolled H-section steel formed by the finish rolling process are the predetermined hole tip angle (inside the hole mold) in FIG.
- the interrupt length H may be set so as to satisfy the interrupt length H based on the hole type of the peripheral protrusion tip angle) and the following equation (1). H ⁇ 0.5F-0.5T (1)
- the lower limit of the interrupt length H is 0.5F-0 with respect to the thickness T of the steel piece having a rectangular cross section and the width F of the flange of the rolled H-section steel formed by the finish rolling process. .5T or more. This is to suppress the amount of reduction in the obtuse hole type in which the central segregation part easily aggregates by performing rolling shaping by the split method until the flange width after rough rolling becomes equal to the flange width of the product. .
- the upper limit of the interrupt length H is not particularly set, but if it exceeds 0.8F-0.5T, excessive edging rolling is required at the time of intermediate rolling, and productivity is lowered, so 0.8F-0.5T or less is desirable.
- the hole tip angle shown in FIGS. 1B and 5 may be an angle that is sufficiently acute to form an interrupt.
- the upper limit is 40 °. It may be set to. This is because when the die tip angle exceeds 40 °, the center segregation portion of the slab is not dispersed by the flange and aggregates in the fillet portion as in the edging rolling shown in FIG. When the hole tip angle is set to 40 ° or less, as shown by the split method of FIG.
- the center segregation part is dispersed without being aggregated in the flange during rolling with the interrupt forming hole mold, It becomes possible to suppress a decrease in toughness.
- the hole tip angle There is no particular lower limit for the hole tip angle, but if it is less than 25 °, the roll may be broken during rolling, so 25 ° or more is preferable.
- the center segregation portion of the slab is not divided into the left and right flanges in the I posture as shown in FIG.
- the center segregation portion is dispersed in the flange portion, and from the vicinity of the center of the flange width in the flange to the flange width direction. It remains in an area of 15 mm or more toward one end face or both end faces and within 2 mm in the thickness direction in the flange surface layer (from the flange face located on the side opposite to the web in the flange thickness direction).
- the central segregation portion dispersed in the flange portion remains over a predetermined length in the region.
- the central segregation portion dispersed in the vicinity of the surface layer can be revealed by identification with the aforementioned nital corrosion solution.
- the upper 5% average concentration of Mn in the central segregation part dispersed in the vicinity of the surface layer is defined as (CMn-surface), and the segregation degree (CMn-surface) / (CMn) at this position is 1.1 or more and 1.6 or less It is desirable that In the split method, the segregation degree of the flange surface layer tends to be higher than in the edging method.
- the degree of segregation is 1.1 or more, there is an advantage that surface cracks can be visually confirmed and inspection becomes easy, and it is also possible to trace a plurality of manufactured products as individual bodies based on surface cracks. Is possible.
- the degree of segregation exceeds 1.6, a large number of cracks are easily formed on the flange surface. Therefore, the degree of segregation is desirably 1.1 or more and 1.6 or less.
- the method for obtaining the upper 5% average concentration in (CMn-surface) is the same as the method for obtaining the upper 5% average concentration in (CMn-max). That is, the method for obtaining the numerical value is basically the same except that the sampling position of the sample is different.
- Control rolling is a manufacturing method for controlling the rolling temperature and the rolling reduction.
- water-cooled rolling process between passes water cooling is performed between rolling passes to give a temperature difference between the surface layer portion and the inside of the flange and roll.
- the inter-pass water-cooled rolling process is, for example, a manufacturing method in which the flange surface temperature is water-cooled to 700 ° C. or lower by water cooling between rolling passes and then rolled in the reheating process.
- water cooling between rolling passes it is preferable to perform water cooling between rolling passes using water cooling devices provided before and after the intermediate universal rolling mill, and repeats spray cooling and reverse rolling of the flange outer surface by the water cooling device. Preferably it is done.
- the inter-pass water-cooled rolling process even when the rolling reduction is small, it is possible to introduce a processing strain to the inside of the plate thickness. Further, productivity is improved by lowering the rolling temperature in a short time by water cooling.
- the central segregation portion existing in the slab before rolling shaping is dispersed without being aggregated in the fillet portion and rolled. Modeling can be completed. Specifically, a rolled H-section steel having a ⁇ vTrs of 40 ° C. or less is manufactured in the flange after the rolling shaping, and the segregation degree thereof is 1.6 or less (see FIG. 2).
- the central segregation portion aggregates in the fillet portion of the flange and adversely affects toughness and embrittlement characteristics. That is, the manufacture of H-shaped steel products having excellent toughness and embrittlement characteristics is realized.
- the center segregation part dispersed in the flange is 15 mm or more from the center of the flange width toward one end surface or both end surfaces in the flange width direction, and from the surface located on the side opposite to the web in the flange thickness direction.
- various inspections and experiments have been conventionally required to investigate the internal state of the flange, but in the H-section steel product according to the present embodiment, the flange surface located on the opposite side of the web is visually examined. be able to.
- a sample was collected from a rolled H-section steel manufactured to satisfy the component composition and manufacturing conditions described in the above embodiment, and the sample was subjected to chemical analysis.
- a sample was taken from a rolled H-section steel that did not satisfy any of the component composition and manufacturing conditions described in the above embodiment, and the same chemical analysis was performed.
- Example No. Steels having a composition (unit: mass%) shown in Table 1 were melted as 1 to 13 and 28, and steel pieces having a thickness of 250 to 300 mm were produced by continuous casting.
- the steel was melted in a converter, subjected to primary deoxidation, an alloy was added to adjust the components, and vacuum degassing was performed as necessary.
- the obtained steel slab was hot-rolled on the manufacturing conditions shown in Table 2.
- hot rolling following rough rolling, using an intermediate universal rolling mill and a water cooling device provided before and after that, spray cooling of the flange outer surface, reverse rolling, and water cooling after rolling were performed as necessary. .
- CMn-max was measured and calculated by EPMA and (CMn) by the method described in JIS G0404 (2014 edition). Further, center segregation remains within 2 mm of the surface layer over 15 mm or more from the center of the flange width toward at least one end face in the flange width direction, and the center segregation parallel to the flange thickness direction is performed as the Mn concentration of the surface layer portion.
- CMn-surface was measured and calculated by EPMA for a region 10 mm below the flange surface layer in the thickness direction (see FIG. 3). The measurement and calculation results are shown in Table 3 below.
- the target value of each characteristic of the H-section steel to be manufactured has a yield point (YP) at normal temperature or a 0.2% proof stress of 335 MPa or more, a tensile strength (TS) of 450 MPa or more, and ⁇ vTrs of 40 ° C. or less.
- the intensity at normal temperature is in the target range, and ⁇ vTrs satisfies the target value of 40 ° C. or less.
- the segregation degree of Mn was 1.6 or less.
- the segregation degree of Mn is desirably 1.5 or less, and more desirably 1.4 or less.
- No. 14 16 and 18 are insufficient in strength due to the small amounts of C, Mn and Si.
- No. 15 has a large amount of C.
- No. 17 has a large amount of Si, and vTrs at F / 6-t / 4 is 0 ° C. or more due to the increase and coarsening of the hard phase, and the toughness is also lowered in the most brittle part.
- No. No. 19 has a large amount of Mn, vTrs at F / 6-t / 4 is 0 ° C. or more, the central segregation degree is deteriorated in the most brittle part, and the toughness is deteriorated by MnS and MA.
- No. No. 20 has a large amount of P. No.
- No. 21 has a large amount of S and has a low toughness.
- No. No. 22 has a rough rolling hole tip angle of more than 40 °, and the slab center segregation portion is aggregated without being dispersed, so that the toughness of the most brittle portion is lowered.
- No. 23 and 24 the length of the interruption is insufficient, and the slab center segregation part is aggregated without being dispersed, so that the toughness of the most brittle part is lowered.
- No. No. 25 has a large amount of Nb.
- No. 26 has a large amount of Mo.
- No. 27 has a large amount of REM, and the toughness of the most brittle part is lowered.
- the present invention can be applied to a rolled H-section steel manufactured by hot-rolling a steel slab and a manufacturing method thereof.
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Abstract
Description
本願は、2016年8月29日に日本国に出願された特願2016-166535号に基づき、優先権を主張し、その内容をここに援用する。
本発明の要旨は以下のとおりである。
C:0.01~0.25%、
Si:0.05%~0.50%、
Mn:0.40~2.50%、
P:0.050%以下、
S:0.050%以下、
N:0.020%以下、
Cu:0.70%以下、
Ni:0.70%以下、
Cr:0.50%以下、
V:0.12%以下、
Mo:0.30%以下、
Nb:0.08%以下、
Ti:0.05%以下、
Al:0.07%以下、
REM:0.010%以下、
Ca:0.0050%以下、
残部:Fe及び不可避不純物、
である化学組成を有する圧延H形鋼であって、フランジにおける最脆化部でのMn濃度の上位5%平均値が、フランジ幅方向の端面からフランジ幅方向に1/6の位置、且つ、ウェブと反対側に位置するフランジの面からフランジ厚方向に1/4の位置におけるMn濃度の1.6倍以下であり、フランジ幅の中心からフランジ幅方向の一方の端面あるいは両端面に向かって15mm以上、且つ、厚み方向でフランジ表層2mm以内の領域に分散される中心偏析部でのMn濃度の上位5%平均値が、フランジ幅方向の端面からフランジ幅方向に1/6の位置、且つ、ウェブと反対側に位置するフランジの面からフランジ厚方向に1/4の位置におけるMn濃度の1.1倍以上1.6倍以下であることを特徴とする、圧延H形鋼。
[2]矩形断面の鋼片を1100~1350℃に加熱し、順に粗圧延工程、中間圧延工程、仕上圧延工程を行い[1]に記載の圧延H形鋼を製造する製造方法であって、前記粗圧延工程を行う圧延機には、被圧延材を造形する3以上の複数の孔型が設けられ、前記複数の孔型の少なくとも一つは、被圧延材の幅方向に対し鉛直に割り込みを入れる突起部が形成された上下一対のロールに設けられている割り込み形成用孔型であり、前記割り込み形成用孔型の後段において、当該割り込み形成用孔型によって形成された分割部位を順次折り曲げる造形用孔型が設けられることを特徴とする、圧延H形鋼の製造方法。
[3]前記割り込み形成用孔型に形成されている突起部の先端角度は40°以下であることを特徴とする、[2]に記載の圧延H形鋼の製造方法。
[4]前記突起部によって形成された割り込みの長さHと、前記矩形断面の鋼片の厚さTと、仕上圧延工程によって形成された圧延H形鋼のフランジの幅Fとが、以下の式(1)を満たすことを特徴とする、[2]又は[3]に記載の圧延H形鋼の製造方法。
H≧0.5F-0.5T ・・・(1)
なお、本実施の形態に係るフランジ部を曲げて圧延造形を行うようなH形鋼の製造方法を本明細書では「スプリット法」と呼称する。
即ち、図1(a)に示すように、エッジング法では孔型ロールによってスラブを幅方向に圧延する際に、中心偏析部がフィレット部に凝集することが分かっている。一方、図1(b)に示すように、スプリット法ではスラブを幅方向にほとんど圧延せず、フランジ部を割り広げるといった方法を採るため、中心偏析部がフランジ部全体で分散され、フィレット部に凝集することなく粗圧延が行われる。特に、割り込み用の孔型の突起部先端角度を40°以下の鋭角とすることで、中心偏析部の凝集を抑制させることが可能であることが分かってきている。
Cは、フィレット部でのMA生成を促進し、靭性を低下させる。しかし、Cは安価に強度を向上させる事が可能であり、製鋼の工程上Cを完全に除去することはコストの増加につながることから、C量を0.01%以上とする。一方、C量が0.25%を超えるとフィレット部の中心偏析部が凝集した位置においてMAが増加し、靱性が低下するため、C量を0.25%以下に制限する。好ましくはC量を0.20%以下、より好ましくは0.17%未満とする。
Siは、脱酸元素であり、強度の向上にも寄与するが、Cと同様、MAを生成させる元素である。Si量が0.50%を超えると、硬質相の生成によって母材及び溶接熱影響部の靭性が低下するため、Si量を0.50%以下に制限する。Si量は、0.30%以下が好ましく、より好ましくは0.20%以下、更に好ましくは0.10%以下とする。しかし、Siを含有させないと脱酸の工程上コストが増加することから、Siを0.05%以上含有させる。
エッジング法により製造されたH形鋼はスラブの中心偏析部がフィレット部に凝集する。Mnは特に中心偏析部に凝集しやすく、局所的にMnの濃度が上昇することで脆化相であるMAの形成、粗大な組織である上部ベイナイトの増加、MnSの増加、焼入れ性の上昇による硬さの増大が促進される。この結果、靭性が著しく低下する。特に、2.50%を超えるMnを含有させると、フィレット部において、介在物の増加等によって母材および溶接熱影響部の靱性を損なう。このため、Mn量を2.50%以下に制限する。Mn量は好ましくは2.00%以下、より好ましくは1.80%以下とする。一方、Mnは結晶粒径の微細化に効果的な元素であるため、0.40%以上を含有させる。
Pは、凝固偏析による溶接割れ、靱性低下の原因となるので、極力低減すべきである。P量は0.050%以下に制限することが好ましく、更に好ましくは0.010%以下である。なお、下限については、0.001%未満まで除去すると製鋼コストが大きく上昇するため、0.001%以上であってもよい。
Sは、凝固偏析により形成された中心偏析部においてMnSを形成し、溶接割れ、靱性低下だけではなく水素割れ等の原因となるので、極力低減すべきである。S量は0.050%以下に制限することが好ましく、更に好ましくは0.010%以下である。なお、下限については、0.001%未満まで除去すると製鋼コストが大きく上昇するため、0.001%以上であってもよい。
Cuは、強度の向上に寄与する元素である。しかし、Cu量が0.70%を超えると強度が過剰に上昇し、靭性が低下するため、Cu量を0.70%以下に制限する。Cu量は好ましくは0.50%以下とし、より好ましくは0.30%以下、更に好ましくは0.10%以下とする。Cu量の下限は0.01%が好ましい。
Niは、強度及び靭性を高めるために、極めて有効な元素である。しかし、Niは高価な元素であり、合金コストの上昇を抑制するため、Ni量を0.70%以下に制限し、好ましくは0.50%以下、より好ましくは0.30%以下、更に好ましくは0.10%以下とする。Ni量は0.01%以上が好ましく、より好ましくは0.02%以上とする。
Crも強度の向上に寄与する元素である。しかし、0.50%を超えてCrを添加すると炭化物を生成し、靭性を損なうことがあるため、Cr量を0.50%以下に制限し、好ましくは0.30%以下とする。Cr量の下限は好ましくは0.01%とする。
Vは、窒化物(VN)を形成する元素であり、母材の強度を高めるために0.01%以上を含有させてもよい。好ましくはV量を0.02%以上、より好ましくは0.03%以上とする。一方、Vは高価な元素であるため、V量の上限は0.12%に制限し、好ましくは0.08%に制限する。
Moは、焼入れ性を高め、強度の向上に寄与する元素である。しかし、0.30%を超えてMoを添加すると、Mo炭化物(Mo2C)の析出やフィレット部におけるMAの生成を促進し、特に溶接熱影響部の靱性を劣化させることがあるため、Mo量を0.30%以下に制限し、好ましくは0.15%以下とする。Mo量の下限は0.01%が好ましい。
Nbはフェライトを微細化させ、靭性を向上させる元素である。しかし、0.08%を超えて添加するとフェライト変態を過剰に抑制し、MAの生成を促進するため、Nb量を0.08%以下に制限し、好ましくは0.05%以下、さらに好ましくは0.03%以下とする。
Tiは、TiNを形成する元素であり、Ti量が0.05%を超えるとTiNが粗大化し、脆性破壊の起点となるため、Ti量を0.05%以下に制限する。好ましくはTi量を0.03%以下、より好ましくは0.02%以下とする。Ti量の下限は0%でもよいが、微細なTiNは組織の微細化に寄与するため、0.005%以上を含有させてもよい。
Alは、脱酸元素であるが、Al量が0.07%を超えると、介在物によって母材及び溶接熱影響部の靭性が低下するため、Al量を0.07%以下に制限する。Al量は、0.05%以下が好ましく、より好ましくは0.04%以下、更に好ましくは0.03%以下とする。Al量の下限は規定せず、0%でもよいが、Alは有用な脱酸元素であり、0.01%以上を含有させても良い。
Nは、母材及び溶接熱影響部の靭性を低下させる元素である。N量が0.020%を超えると、固溶Nや粗大な析出物の形成によって低温靭性を損なうため、N量を0.020%以下に制限する。N量は好ましくは0.010%以下、より好ましくは0.007%以下とする。一方、N量を0.002%未満に低減しようとすると製鋼コストが高くなるため、N量は0.002%以上であってもよい。コストの観点からN量は0.003%以上であってもよい。
REM及びCaは、脱酸元素であり、硫化物の形態の制御にも寄与するため、添加してもよい。しかし、REM、Caの酸化物は溶鋼中で容易に浮上するため、鋼中に含有されるREM量を0.010%以下、Ca量を0.0050%以下に制限する。REM量及びCa量の下限は、好ましくは、それぞれ0.0005%とする。
なお、本明細書では、当該位置を、フランジ幅Fとフランジ厚tとを用いて「F/6-t/4」と表記する。
とした。
一方、F/6-t/4の位置よりサンプルを採取し、JIS G0404(2014年版)に従い、当該サンプルの化学成分を分析して求めたMn濃度の値をF/6-t/4の位置におけるMn濃度(CMn)とした。更に、(CMn-max)を(CMn)で除した値(CMn-max)/(CMn)を偏析度として評価した。
図2に示すように、従来のエッジング法で製造された圧延H形鋼の場合は、偏析度が1.6を超えていると共に、最脆化部と、F/6-t/4の位置とのシャルピー遷移温度差ΔvTrsが40℃を超えている。この状態では最脆化部にMnが多く偏析することによってMnS、硬質相である島状マルテンサイト(MA)、上部ベイナイト等が形成され、脆化が抑制できなくなる。
一方、スプリット法で製造された圧延H形鋼は、最脆化部と、F/6-t/4の位置とのシャルピー遷移温度差ΔvTrsが40℃以下である。即ち、偏析度が1.6以下となった状態では、中心偏析部の凝集が抑制され、従来品よりもフランジにおける断面内の均一性に優れた圧延H形鋼が得られる。
なお、一般的な温度条件で使用される鋼構造建築物が地震力等を受けるとき、部材のH形鋼が脆性破壊することなく所定の機械的特性を満たすためには、F/6-t/4の位置のvTrsが0℃以下であることが望ましい。
鋼片の加熱温度は、1100~1350℃とする。加熱温度が低いと変形抵抗が高くなるので、熱間圧延における造形性を確保するために1100℃以上とする。一方、鋼片の加熱温度が1350℃を超えると、素材である鋼片の表面の酸化物が溶融して加熱炉内が損傷することがある。Nbなど、析出物を形成する元素を十分に固溶させるためには、鋼片の加熱温度の下限を1150℃以上とすることが好ましい。特に、製品の板厚が薄い場合は、累積圧下率が大きくなるため、鋼片の加熱温度を1200℃以上にすることが好ましい。組織を微細にするためには、鋼片の加熱温度の上限を1300℃以下にすることが好ましい。
スプリット法による粗圧延では、矩形断面の鋼片の厚さTと、仕上圧延工程によって形成された圧延H形鋼のフランジの幅Fとが、図5における所定の孔型先端角度(孔型内周の突起部先端角度)の孔型による割り込み長さHと下記式(1)を満足するように割り込み長さHを設定しても良い。
H≧0.5F-0.5T ・・・(1)
図1(b)、図5に示した孔型先端角度(孔型内周の突起部先端角度)については、割り込みを形成させるのに十分鋭角な角度とすれば良く、例えばその上限は40°に設定しても良い。型先端角度が40°を超えるとスラブの中心偏析部がフランジで分散されず、図1(a)に示すエッジング圧延同様にフィレット部に凝集するためである。孔型先端角度を40°以下とすることで図1(b)のスプリット法で示すように割り込み形成用孔型での圧延時に中心偏析部がフランジ内で凝集せずに分散し、フィレット部における靭性の低下を抑制することが可能となる。
孔型先端角度の下限は特に設けないが、25°を下回ると圧延時にロールが折損する可能性があるため、25°以上が好ましい。
なお、この際、スラブの中心偏析部は図1(b)に示すようにI姿勢での左右フランジに分かれるのではなく、左右どちらかのフランジに分散されてもよい。
表層付近に分散される中心偏析部でのMnの上位5%平均濃度を(CMn-surface)とし、この位置における偏析度(CMn-surface)/(CMn)は、1.1以上1.6以下であることが望ましい。スプリット法ではエッジング法に比べて、フランジ表層の偏析度が高くなる傾向にある。偏析度が1.1以上であると、表面のクラックを目視で確認でき検査が容易になるメリットがあり、また、表面のクラックに基づき、複数製造される製品をそれぞれの個体としてトレースすることも可能である。一方で、当該偏析度が1.6を超えると、フランジ表面に多数のクラックが入り易くなるため、偏析度は1.1以上1.6以下であることが望ましい。なお、(CMn-surface)における上位5%平均濃度の求め方は、上記(CMn-max)における上位5%平均濃度の求め方に準ずるものとする。即ち、サンプルの採取位置が異なるだけで、数値の求め方は基本的に同じである。
熱間圧延の中間圧延工程では、中間ユニバーサル圧延機による制御圧延を行ってもよい。制御圧延は、圧延温度及び圧下率を制御する製造方法である。熱間圧延の中間圧延では、パス間水冷圧延加工を1パス以上施すことが好ましい。パス間水冷圧延加工では、圧延パス間で水冷を行うことにより、フランジの表層部と内部とに温度差を付与し、圧延する。パス間水冷圧延加工は、例えば、圧延パス間における水冷により、700℃以下にフランジ表面温度を水冷した後、復熱過程で圧延する製造方法である。
先ず、実施例のNo.1~13、28として、表1に示す成分組成(単位:質量%)を有する鋼を溶製し、連続鋳造により、厚みが250~300mmの鋼片を製造した。鋼の溶製は転炉で行い、一次脱酸し、合金を添加して成分を調整し、必要に応じて、真空脱ガス処理を行った。そして、得られた鋼片を表2に示す製造条件で熱間圧延を行った。熱間圧延では、粗圧延に続いて、中間ユニバーサル圧延機と、その前後に設けた水冷装置とを用いて、必要に応じてフランジ外側面のスプレー冷却とリバース圧延および圧延後の水冷を行った。
また、フランジ幅の中心からフランジ幅方向の少なくとも一方の端面に向かって15mm以上にわたって、表層2mm以内に中心偏析が残存しており、表層部のMn濃度として、フランジ厚方向と平行な中心偏析を含まず、且つ厚み方向でフランジ表層下10mmの領域(図3参照)について、EPMAにより(CMn-surface)を測定及び算出した。
測定・算出結果を以下の表3に示す。
比較例のNo.14~27として、表4に示す成分組成を有する鋼を溶製し、上記実施例と同様の方法で厚みが250~300mmの鋼片を製造した。そして、得られた鋼片を表5に示す製造条件で熱間圧延を行った。
なお、以下の表4及び表5において下線を付した箇所は、上記実施の形態で説明した本発明に係る成分組成及び製造条件を満たさない箇所である。
測定・算出結果を以下の表6に示す。なお、以下の表6において下線を付した箇所は、製造すべきH形鋼の各特性の目標値から外れた値である。
Claims (4)
- 質量%で、
C:0.01~0.25%、
Si:0.05%~0.50%、
Mn:0.40~2.50%、
P:0.050%以下、
S:0.050%以下、
N:0.020%以下、
Cu:0.70%以下、
Ni:0.70%以下、
Cr:0.50%以下、
V:0.12%以下、
Mo:0.30%以下、
Nb:0.08%以下、
Ti:0.05%以下、
Al:0.07%以下、
REM:0.010%以下、
Ca:0.0050%以下、
残部:Fe及び不可避不純物、
である化学組成を有する圧延H形鋼であって、
フランジにおける最脆化部でのMn濃度の上位5%平均値が、フランジ幅方向の端面からフランジ幅方向に1/6の位置、且つ、ウェブと反対側に位置するフランジの面からフランジ厚方向に1/4の位置におけるMn濃度の1.6倍以下であり、
フランジ幅の中心からフランジ幅方向の一方の端面あるいは両端面に向かって15mm以上、且つ、厚み方向でフランジ表層2mm以内の領域に分散される中心偏析部でのMn濃度の上位5%平均値が、フランジ幅方向の端面からフランジ幅方向に1/6の位置、且つ、ウェブと反対側に位置するフランジの面からフランジ厚方向に1/4の位置におけるMn濃度の1.1倍以上1.6倍以下であることを特徴とする、圧延H形鋼。 - 矩形断面の鋼片を1100~1350℃に加熱し、順に粗圧延工程、中間圧延工程、仕上圧延工程を行い請求項1に記載の圧延H形鋼を製造する製造方法であって、
前記粗圧延工程を行う圧延機には、被圧延材を造形する3以上の複数の孔型が設けられ、
前記複数の孔型の少なくとも一つは、被圧延材の幅方向に対し鉛直に割り込みを入れる突起部が形成された上下一対のロールに設けられている割り込み形成用孔型であり、
前記割り込み形成用孔型の後段において、当該割り込み形成用孔型によって形成された分割部位を順次折り曲げる造形用孔型が設けられることを特徴とする、圧延H形鋼の製造方法。 - 前記割り込み形成用孔型に形成されている突起部の先端角度は40°以下であることを特徴とする、請求項2に記載の圧延H形鋼の製造方法。
- 前記突起部によって形成された割り込みの長さHと、前記矩形断面の鋼片の厚さTと、仕上圧延工程によって形成された圧延H形鋼のフランジの幅Fとが、以下の式(1)を満たすことを特徴とする、請求項2又は3に記載の圧延H形鋼の製造方法。
H≧0.5F-0.5T ・・・(1)
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Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS58188501A (ja) * | 1982-04-30 | 1983-11-04 | Sumitomo Metal Ind Ltd | H形鋼用粗形鋼片の製造方法 |
JPH0788502A (ja) * | 1993-09-27 | 1995-04-04 | Nippon Steel Corp | H形鋼の圧延方法 |
JP2012180584A (ja) * | 2011-03-03 | 2012-09-20 | Jfe Steel Corp | 靭性に優れる圧延h形鋼およびその製造方法 |
Family Cites Families (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA1179171A (en) * | 1981-07-10 | 1984-12-11 | Yoshiaki Kusaba | Method for producing beam blank for universal beam |
JPS6021101A (ja) * | 1983-07-14 | 1985-02-02 | Sumitomo Metal Ind Ltd | 形鋼の粗形鋼片圧延方法 |
JPS6182903A (ja) * | 1984-09-28 | 1986-04-26 | Sumitomo Metal Ind Ltd | フランジ内面に突起を有するh形鋼の圧延法 |
JPH0199701A (ja) * | 1987-10-09 | 1989-04-18 | Sumitomo Metal Ind Ltd | H形鋼の粗圧延方法 |
JPH05305395A (ja) | 1992-05-07 | 1993-11-19 | Nippon Steel Corp | 連続鋳造方法 |
JP2672236B2 (ja) | 1992-10-12 | 1997-11-05 | 新日本製鐵株式会社 | 靱性の優れたh形鋼の製造方法 |
JP2698006B2 (ja) | 1992-10-12 | 1998-01-19 | 新日本製鐵株式会社 | 靱性の優れたh形鋼の製造方法 |
JP2837056B2 (ja) * | 1993-02-04 | 1998-12-14 | 新日本製鐵株式会社 | 制御圧延による低炭素当量圧延形鋼の製造方法 |
WO1997023310A1 (fr) * | 1995-12-21 | 1997-07-03 | Nippon Steel Corporation | Procede et appareil de laminage de profile d'acier |
CN1168549C (zh) * | 1998-04-15 | 2004-09-29 | 新日本制铁株式会社 | 工字钢轧制设备用多功能轧机及使用该轧机的轧制方法 |
CN1504276A (zh) * | 2002-12-02 | 2004-06-16 | 李宝安 | 普通三辊轧机轧制h型钢的工艺方法 |
JP2006063443A (ja) * | 2004-07-28 | 2006-03-09 | Nippon Steel Corp | 耐火性に優れたh形鋼およびその製造方法 |
CN103056160A (zh) * | 2013-01-24 | 2013-04-24 | 中冶赛迪工程技术股份有限公司 | H型钢的x-i短流程轧制机组 |
EP2975149B1 (en) * | 2013-03-14 | 2019-05-01 | Nippon Steel & Sumitomo Metal Corporation | H-shaped steel and process for manufacturing same |
JP6446716B2 (ja) * | 2015-03-19 | 2019-01-09 | 新日鐵住金株式会社 | H形鋼の製造方法 |
CN105057345B (zh) * | 2015-08-21 | 2017-03-22 | 天津市中重科技工程有限公司 | 一种万能轧机劈轧板坯生产h型钢的方法 |
KR20180097665A (ko) * | 2016-01-07 | 2018-08-31 | 신닛테츠스미킨 카부시키카이샤 | H형 강의 제조 방법 및 압연 장치 |
-
2017
- 2017-08-29 JP JP2018525629A patent/JP6421900B2/ja active Active
- 2017-08-29 US US16/327,280 patent/US20190184436A1/en not_active Abandoned
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-
2019
- 2019-01-09 PH PH12019500064A patent/PH12019500064A1/en unknown
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS58188501A (ja) * | 1982-04-30 | 1983-11-04 | Sumitomo Metal Ind Ltd | H形鋼用粗形鋼片の製造方法 |
JPH0788502A (ja) * | 1993-09-27 | 1995-04-04 | Nippon Steel Corp | H形鋼の圧延方法 |
JP2012180584A (ja) * | 2011-03-03 | 2012-09-20 | Jfe Steel Corp | 靭性に優れる圧延h形鋼およびその製造方法 |
Non-Patent Citations (1)
Title |
---|
See also references of EP3483294A4 * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3789508A4 (en) * | 2018-05-16 | 2021-03-10 | Shandong Iron and Steel Co., Ltd. | HIGH Toughness, HOT-ROLLED, LOW-TEMPERATURE-RESISTANT H-BEAM WITH YIELD STRENGTH 460 IN MPA QUALITY AND PROCESS FOR ITS MANUFACTURING |
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