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WO2024162381A1 - Tôle d'acier laminée à chaud - Google Patents

Tôle d'acier laminée à chaud Download PDF

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Publication number
WO2024162381A1
WO2024162381A1 PCT/JP2024/003020 JP2024003020W WO2024162381A1 WO 2024162381 A1 WO2024162381 A1 WO 2024162381A1 JP 2024003020 W JP2024003020 W JP 2024003020W WO 2024162381 A1 WO2024162381 A1 WO 2024162381A1
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Prior art keywords
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hot
gam
content
rolled steel
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PCT/JP2024/003020
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English (en)
Japanese (ja)
Inventor
隆 安富
竜大 服部
昌史 東
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Nippon Steel Corp
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Nippon Steel Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Priority to CN202480008616.5A priority Critical patent/CN120569506A/zh
Priority to KR1020257022668A priority patent/KR20250118850A/ko
Priority to JP2024574966A priority patent/JPWO2024162381A1/ja
Priority to EP24750330.3A priority patent/EP4660342A1/fr
Publication of WO2024162381A1 publication Critical patent/WO2024162381A1/fr
Priority to MX2025008622A priority patent/MX2025008622A/es
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • 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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    • 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
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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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
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
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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
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
    • C—CHEMISTRY; METALLURGY
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    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
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    • 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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    • C22C38/00—Ferrous alloys, e.g. steel alloys
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • 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
    • C21D2211/001—Austenite
    • 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
    • C21D2211/002—Bainite

Definitions

  • the present invention relates to a hot-rolled steel sheet.
  • This application claims priority based on Japanese Patent Application No. 2023-013129, filed on January 31, 2023, the contents of which are incorporated herein by reference.
  • Patent Document 1 discloses a high-strength steel plate whose metal structure is essentially a two-phase structure of ferrite and bainite, and in which carbides containing Ti and Mo are dispersed and precipitated in the ferrite phase.
  • Patent Document 1 does not take into consideration ductility and hole expansion properties.
  • the above-mentioned automobile suspension parts are manufactured by subjecting hot-rolled steel sheets to multiple forming steps. Therefore, hot-rolled steel sheets used in automobile suspension parts are required to have excellent bendability even after being subjected to a certain degree of pre-strain in a previous process. If a compound deformation including compression is caused as pre-strain in a multiple-step forming process, the unevenness of the surface of the hot-rolled steel sheet will develop to a large extent, increasing the risk of breakage in the subsequent bending process. The inventors have discovered that this issue does not occur with cold-rolled steel sheets, which have a small surface roughness, but is an issue specific to hot-rolled steel sheets.
  • the present invention has been made in consideration of the above-mentioned circumstances.
  • the object of the present invention is to provide a hot-rolled steel sheet that has high strength, excellent ductility and hole expansion properties, as well as excellent bendability after pre-straining.
  • a hot-rolled steel sheet according to one embodiment of the present invention has a chemical composition, in mass%, C: 0.045-0.120%, Si: 0-3.00%, Mn: 1.20-2.60%, Ti: 0.020 to 0.180%, Al: 0.010-0.400%, P: 0.080% or less, S: 0.0100% or less, N: 0.0050% or less, O: 0.010% or less, Nb: 0 to 0.100%, V: 0 to 1.000%, Cu: 0 to 1.000%, Cr: 0-2.000%, Mo: 0-3.000%, Ni: 0 to 0.500%, B: 0 to 0.0100%, Ca: 0-0.0500%, Mg: 0 to 0.0500%, REM: 0-0.100%, Bi: 0-0.100%, Ta: 0-0.100%, Zr: 0 to 0.500%, Co: 0-3.000%, Zn: 0-0.200%, W: 0-0.200%,
  • 11A to 11C are diagrams for explaining a method for forming the hat part.
  • the chemical composition of the hot-rolled steel sheet according to this embodiment is, in mass%, C: 0.045 to 0.120%, Si: 0 to 3.00%, Mn: 1.20 to 2.60%, Ti: 0.020 to 0.180%, Al: 0.010 to 0.400%, P: 0.080% or less, S: 0.0100% or less, N: 0.0050% or less, and the balance: Fe and impurities.
  • C 0.045 to 0.120%
  • Si 0 to 3.00%
  • Mn 1.20 to 2.60%
  • Ti 0.020 to 0.180%
  • Al 0.010 to 0.400%
  • P 0.080% or less
  • S 0.0100% or less
  • N 0.0050% or less
  • Fe and impurities each element will be described in detail below.
  • C 0.045-0.120%
  • C is an element necessary for obtaining a desired tensile strength of the hot-rolled steel sheet. If the C content is less than 0.045%, the desired tensile strength cannot be obtained in the hot-rolled steel sheet. Therefore, the C content is set to 0.045% or more.
  • the C content is preferably 0.050% or more, more preferably 0.060% or more, and even more preferably 0.080% or more. be. On the other hand, if the C content exceeds 0.120%, the hole expandability of the hot-rolled steel sheet deteriorates. Therefore, the C content is set to 0.120% or less.
  • the C content is preferably 0.110% or less. and more preferably 0.100% or less.
  • Si 0-3.00% Si is an element that improves the tensile strength of a hot-rolled steel sheet by solid solution strengthening.
  • the hot-rolled steel sheet according to the present embodiment ensures sufficient tensile strength even without containing Si.
  • the Si content may be 0%.
  • the Si content is preferably 0.01% or more, and more preferably 0.03% or more.
  • the Si content is set to 3.00% or less.
  • the Si content is preferably 2.00% or less.
  • the Si content is set to 0 to 3.00%, thereby improving the strength and It is possible to achieve a good balance between elongation and hole expandability.
  • Mn 1.20-2.60%
  • Mn is an element necessary for improving the strength of a hot-rolled steel sheet. If the Mn content is less than 1.20%, the desired tensile strength cannot be obtained in the hot-rolled steel sheet.
  • the Mn content is 1.20% or more, preferably 1.40% or more, and more preferably 1.60% or more. On the other hand, if the Mn content exceeds 2.60%, the hole expandability of the hot-rolled steel sheet deteriorates. Therefore, the Mn content is set to 2.60% or less.
  • the Mn content is preferably 2.30% or less. % or less, and more preferably 2.20% or less.
  • Ti 0.020-0.180%
  • Ti is an element that forms fine nitrides in steel to increase the strength of the hot-rolled steel sheet. If the Ti content is less than 0.020%, the desired tensile strength cannot be obtained in the hot-rolled steel sheet. Therefore, the Ti content is set to 0.020% or more, preferably 0.050% or more, and more preferably 0.080% or more. On the other hand, if the Ti content exceeds 0.180%, the hole expandability of the hot-rolled steel sheet deteriorates. Therefore, the Ti content is set to 0.180% or less.
  • the Ti content is preferably 0. It is preferably 160% or less, and more preferably 0.150% or less.
  • Al 0.010-0.400%
  • Al is an element that acts as a deoxidizer and improves the cleanliness of steel. If the Al content is less than 0.010%, a sufficient deoxidizing effect cannot be obtained, and a large amount of Al inclusions in the steel are generated. Such inclusions deteriorate the workability, particularly the hole expandability, of the hot-rolled steel sheet. Therefore, the Al content is set to 0.010% or more.
  • the Al content is , preferably 0.020% or more, and more preferably 0.030% or more. On the other hand, if the Al content exceeds 0.400%, casting becomes difficult. Therefore, the Al content is set to 0.400% or less.
  • the Al content is preferably set to 0.300% or less, and more preferably 0.400% or less. It is preferably 0.200% or less, and even more preferably 0.100% or less.
  • P 0.080% or less
  • P is an element that segregates at grain boundaries in steel and promotes embrittlement of the grain boundaries. If the P content is too high, the elongation and hole expandability of the hot-rolled steel sheet are likely to decrease, and further, cracks in the slab due to embrittlement may occur, making hot rolling difficult. Therefore, the P content is set to 0.080% or less.
  • the P content is preferably 0.020% or less, and more preferably 0.010% or less. The lower the P content, the better, and 0% is preferable. However, if the P content is excessively reduced, the dephosphorization cost increases significantly, so the P content may be 0.001% or more.
  • S 0.0100% or less
  • S is an element that embrittles the slab when present as a sulfide.
  • S is also an element that deteriorates the workability of the hot-rolled steel sheet. If the S content exceeds 0.0100%, the hole expandability of the hot-rolled steel sheet deteriorates. Therefore, the S content is set to 0.0100% or less.
  • the S content is preferably 0.0080% or less, more preferably 0.0050% or less. The lower the S content, the better, and 0% is preferable. However, if the S content is excessively reduced, the desulfurization cost increases significantly, so the S content may be 0.0005% or more.
  • N 0.0050% or less
  • N is an element that forms coarse nitrides in steel and deteriorates the hole expandability of hot-rolled steel sheets. If the N content is too high, excessive nitrides are generated, which can easily reduce the elongation and hole expandability of the hot-rolled steel sheet, and furthermore, slab cracks due to embrittlement may occur, making hot rolling difficult. Therefore, the N content is set to 0.0050% or less.
  • the N content is preferably 0.0040% or less, and more preferably 0.0035% or less. The lower the N content, the better, and 0% is preferable. However, if the N content is excessively reduced, the cost of denitrification increases significantly, so the N content may be 0.0005% or more.
  • O 0.010% or less
  • O is an element that forms oxides and reduces the workability of hot-rolled steel sheets. If the O content exceeds 0.010%, the hole expandability of the hot-rolled steel sheet is likely to decrease due to excessive generation of oxides, etc. Therefore, the O content is set to 0.010% or less.
  • the O content is preferably 0.008% or less, and more preferably 0.006% or less. The lower the O content, the better, and 0% is preferable. However, if the O content is excessively reduced, the cost of deoxidization increases significantly, so the O content may be 0.001% or more.
  • the remainder of the chemical composition of the hot-rolled steel sheet according to this embodiment may be Fe and impurities.
  • impurities refer to substances that are mixed in from the raw materials such as ore, scrap, or the manufacturing environment, or substances that are acceptable to the extent that they do not adversely affect the hot-rolled steel sheet according to this embodiment.
  • the chemical composition of the hot-rolled steel sheet according to this embodiment may contain the following optional elements instead of a portion of Fe.
  • the lower limit of the content is 0%.
  • Nb 0.001-0.100%
  • Nb is an element that suppresses abnormal grain growth of austenite grains during hot rolling.
  • Nb is also an element that increases the strength of hot-rolled steel sheets by forming fine carbides.
  • the Nb content is preferably 0.001% or more, more preferably 0.010% or more, and even more preferably 0.030% or more.
  • the Nb content is set to 0.100% or less.
  • the Nb content is preferably 0.080% or less, and more preferably 0.060% or less.
  • V is an element that forms fine carbides in steel to increase the strength of the hot-rolled steel sheet.
  • the V content is preferably 0.001% or more.
  • the V content is more preferably 0.050% or more, and even more preferably 0.100% or more.
  • the V content is set to 1.000% or less.
  • the V content is preferably 0.500 % or less, and more preferably 0.300% or less.
  • Cu 0.001-1.000%
  • the Cu content is preferably 0.001% or more, more preferably 0.050% or more, and even more preferably 0.100% or more.
  • the Cu content is set to 1.000% or less.
  • the Cu content is preferably set to 0.500% or less. and more preferably 0.300% or less.
  • Cr:0.001 ⁇ 2.000% Cr is an element that exerts an effect similar to that of Mn.
  • the Cr content is preferably 0.001% or more.
  • the content is more preferably 0.050% or more, and even more preferably 0.100% or more.
  • the Cr content is set to 2.000% or less.
  • the Cr content is preferably is 1.000% or less, and more preferably 0.500% or less.
  • Mo 0.001 ⁇ 3.000%
  • Mo is an element that increases the strength of a hot-rolled steel sheet by forming fine carbides in the steel.
  • the Mo content is preferably 0.001% or more.
  • the Mo content is more preferably 0.050% or more, and even more preferably 0.100% or more.
  • the Mo content is set to 3.000% or less.
  • the Mo content is preferably 2.000% or less. % or less, and more preferably 1.000% or less.
  • Ni 0.001-0.500%
  • Ni is an element that enhances the hardenability of hot-rolled steel sheets.
  • Ni has the effect of effectively suppressing grain boundary cracking of slabs caused by Cu.
  • the Ni content is preferably 0.001% or more, more preferably 0.050% or more, and even more preferably 0.100% or more. be.
  • Ni is an expensive element, so it is economically undesirable to include a large amount of it. Therefore, the Ni content is set to 0.500% or less. From the viewpoint of reducing the alloy cost, the Ni content is , preferably 0.300% or less, and more preferably 0.200% or less.
  • B 0.0001-0.0100%
  • B is an element that increases the strength of a hot-rolled steel sheet.
  • the B content is preferably 0.0001% or more.
  • the B content is more preferably 0.0005% or more. % or more, and more preferably 0.0010% or more.
  • the B content is set to 0.0100% or less.
  • the B content is preferably set to 0.0070% or less. More preferably, it is 0.0050% or less.
  • Ca 0.0001-0.0500%
  • Ca is an element that enhances the ductility and hole expandability of the hot-rolled steel sheet by controlling the shape of inclusions to a preferred shape.
  • the Ca content is set to 0.0001% or more.
  • the Ca content is preferably 0.0010% or more, and more preferably 0.0050% or more.
  • the Ca content exceeds 0.0500%, excessive inclusions are generated in the steel, which may deteriorate the ductility and hole expandability of the hot-rolled steel sheet.
  • the Ca content is preferably 0.0300% or less, and more preferably 0.0100% or less.
  • Mg 0.0001-0.0500%
  • Mg is an element that enhances the ductility and hole expandability of the hot-rolled steel sheet by controlling the shape of inclusions to a preferred shape. In order to reliably obtain this effect, the Mg content should be 0.0001% or more.
  • the Mg content is preferably 0.0010% or more, and more preferably 0.0020% or more.
  • the Mg content exceeds 0.0500%, excessive inclusions are generated in the steel, which may deteriorate the ductility and hole expandability of the hot-rolled steel sheet.
  • the Mg content is preferably 0.0300% or less, and more preferably 0.0100% or less.
  • REM 0.001 ⁇ 0.100% REM is an element that improves the ductility and hole expandability of hot-rolled steel sheets by controlling the shape of inclusions to a preferred shape. To reliably obtain this effect, the REM content should be 0.001% or more.
  • the REM content is preferably 0.003% or more, and more preferably 0.005% or more.
  • the REM content exceeds 0.100%, excessive inclusions are generated in the steel, which may deteriorate the ductility and hole expandability of the hot-rolled steel sheet.
  • the REM content is preferably 0.050% or less, and more preferably 0.030% or less.
  • REM refers to a total of 17 elements consisting of Sc, Y and lanthanoids, and the content of the REM refers to the total content of these elements.
  • lanthanoids they are industrially added in the form of misch metal. will be done.
  • Bi 0.001 ⁇ 0.100%
  • Bi is an element that refines the solidification structure and thereby improves the ductility and hole expandability of the hot-rolled steel sheet.
  • the Bi content must be 0.001% or more.
  • the Bi content is preferably 0.002% or more, and more preferably 0.003% or more.
  • the Bi content is set to 0.100% or less. From the viewpoint of reducing alloy costs, The Bi content is preferably 0.050% or less, and more preferably 0.030% or less.
  • Ta 0.001 ⁇ 0.100%
  • Ta is an element that increases the strength of hot-rolled steel sheets by forming fine carbides in the steel.
  • the Ta content is set to 0.001% or more.
  • the Ta content is more preferably 0.005% or more, and even more preferably 0.010% or more.
  • the Ta content is set to 0.100% or less.
  • the Ta content is preferably 0.080 % or less, and more preferably 0.050% or less.
  • Zr 0.001-0.500%
  • Zr is an element that increases the strength of a hot-rolled steel sheet by solid solution strengthening.
  • the Zr content is preferably 0.001% or more.
  • the Zr content is more preferably is 0.005% or more, and more preferably 0.010% or more.
  • the Zr content is set to 0.500% or less.
  • the Zr content is preferably 0. It is preferably 0.300% or less, and more preferably 0.100% or less.
  • Co is an element that increases the strength of a hot-rolled steel sheet by solid solution strengthening.
  • the Co content is preferably 0.001% or more.
  • the Co content is more preferably is 0.005% or more, and more preferably 0.010% or more.
  • the Co content is set to 3.000% or less.
  • the Co content is preferably 1. It is preferably 0.000% or less, and more preferably 0.500% or less.
  • Zn 0.001-0.200%
  • Zn is an element that increases the strength of a hot-rolled steel sheet by solid solution strengthening.
  • the Zn content is preferably 0.001% or more.
  • the Zn content is more preferably is 0.005% or more, and more preferably 0.010% or more.
  • the Zn content is set to 0.200% or less.
  • the Zn content is preferably 0. .150% or less, more preferably 0.100% or less.
  • W 0.001-0.200%
  • W is an element that increases the strength of a hot-rolled steel sheet by solid solution strengthening.
  • the W content is preferably 0.001% or more.
  • the W content is more preferably is 0.005% or more, and more preferably 0.010% or more.
  • the W content is set to 0.200% or less.
  • the W content is preferably 0. .150% or less, more preferably 0.100% or less.
  • Sb 0.001-0.500%
  • Sb is an element that suppresses the generation of oxides that are the starting points of fracture, thereby improving the ductility and hole expandability of the hot-rolled steel sheet.
  • the Sb content is set to 0.001
  • the Sb content is preferably 0.005% or more, and more preferably 0.10% or more.
  • the Sb content is set to 0.500% or less.
  • the Sb content is preferably 0.300% or less, and more preferably 0.100% or less. % or less.
  • As is an element that reduces the austenite single-phase temperature, thereby refining prior austenite grains and improving the hole expandability of the hot-rolled steel sheet. To reliably obtain this effect, the As content should be kept at 0.
  • the As content is preferably 0.001% or more.
  • the As content is more preferably 0.005% or more, and even more preferably 0.010% or more.
  • the As content is set to 0.050% or less.
  • the As content is preferably set to 0.040% or less, and more preferably set to 0.030% or less. % or less.
  • Sn is an element that suppresses the generation of oxides that are the starting points of fracture, thereby improving the ductility and hole expandability of hot-rolled steel sheets.
  • the Sn content is 0.001% or more.
  • the Sn content is more preferably 0.005% or more, and even more preferably 0.010% or more.
  • the Sn content is set to 0.050% or less.
  • the Sn content is preferably 0.040% or less, and more preferably 0.030% or less. % or less.
  • the chemical composition of the above-mentioned hot-rolled steel sheet may be analyzed using a spark discharge optical emission spectrometer or the like. Note that, for C and S, values identified by burning in an oxygen stream using a gas composition analyzer or the like and measuring by an infrared absorption method are adopted. For N, values identified by melting a test piece taken from the steel sheet in a helium stream and measuring by a thermal conductivity method are adopted. When the hot-rolled steel sheet has a plating layer on the surface, the plating layer may be removed by mechanical grinding or the like, as necessary, before analyzing the chemical composition.
  • the ratio of GAM I which is the area average value of the GAM value of the crystal grains at a position of 1/4 depth from the surface in the sheet thickness direction
  • GAM S which is the area average value of the GAM value of the crystal grains in a region from the surface to a depth of 200 ⁇ m in the sheet thickness direction
  • the area ratio of the region where the GAM value is more than 0.6° is 50% or more
  • the sum of the area ratio of the region where the GAM value is more than 3.0° and the area ratio of retained austenite is less than 15%
  • the standard deviation of the area average value of the GAM value of the crystal grains in the region from the surface to a depth of 200 ⁇ m in the sheet thickness direction is 0.25 to 0.65°.
  • the metal structure is defined as being located at a quarter position in the width direction from the end face.
  • the quarter position in the width direction from the end face here refers to a w/4 position from the end face in the width direction, where w is the length in the width direction. That is, "x/y position from the end face (here, x and y are natural numbers satisfying x ⁇ y)" means a position moved in the width direction from the end face in the width direction of the steel plate toward the center of the steel plate by a distance of x/y of the plate width. For example, when the width of the steel plate is 1 m, "1/4 position from the end face” means a position that is 0.25 m away from the end face in the width direction of the steel plate.
  • plate thickness x/y position (where x and y are natural numbers satisfying x ⁇ y) refers to a position moved in the plate thickness direction from the surface (plate surface) of the steel plate in the plate thickness direction toward the center of the steel plate by a distance (depth) of x/y of the plate thickness t.
  • depth a distance of x/y of the plate thickness t.
  • the plate thickness 1/8 position refers to a position that is 0.25 mm deep from the surface of the steel plate in the plate thickness direction.
  • the "surface of the steel sheet” means the interface between the steel sheet and the coating
  • the "sheet thickness t” means the thickness of the steel sheet (base material) excluding the coating.
  • GAM S / GAM I 0.70-1.05
  • the "Grain Average Misorientation (GAM) value" of crystal grains is measured by the EBSP (Electron Backscatter Pattern) method. Crystal grains with a small GAM value improve the ductility of hot-rolled steel sheets. In addition, while the strength depends on the average characteristics in the thickness direction of the hot-rolled steel sheet, the bendability depends on the characteristics of the sheet surface. found that the strength and bendability after pre-straining of the hot-rolled steel sheet can be improved by arranging crystal grains having a small GAM value and excellent ductility in the surface layer region of the hot-rolled steel sheet.
  • GAM I which is the area average value of the GAM value of the crystal grains at a position 1/4 depth from the surface in the sheet thickness direction (hereinafter sometimes referred to as the internal region)
  • GAM S which is the area average value of the GAM value of the crystal grains in a region from the surface to a depth of 200 ⁇ m in the sheet thickness direction (hereinafter sometimes referred to as the surface layer region )
  • GAM S /GAM I is set to 0.70 or more. It is preferable that GAM S /GAM I is set to 0.80 or more.
  • Standard deviation of the area average value of GAM value of crystal grains in the surface layer region: 0.25 to 0.65° Fracture in hot-rolled steel sheets occurs mainly in crystal grains with large GAM values.
  • crystal grains with small GAM values are preferentially deformed during pre-straining, and by suppressing the deformation of crystal grains with large GAM values, it is possible to suppress the destruction of crystal grains with large GAM values during bending after pre-straining.
  • the standard deviation of the area average value of the GAM value in the region from the surface to a depth of 200 ⁇ m in the sheet thickness direction (surface layer region) is less than 0.25°, it is not possible to suppress the deformation of crystal grains with large GAM values, and it is not possible to obtain the desired bendability after pre-straining. Therefore, the standard deviation of the area average value of the GAM value of the crystal grains in the surface layer region is set to 0.25° or more. It is preferable that the standard deviation of the area average value of the GAM value of the crystal grains in the surface layer region is set to 0.35° or more. On the other hand, if the non-uniformity is too large, excessive strain concentration occurs, which causes deterioration of the bendability after the pre-strain is applied.
  • the standard deviation of the area average value of the GAM value of the crystal grains in the surface layer region is set to 0.65° or less. It is preferable that the standard deviation of the area average value of the GAM value of the crystal grains in the surface layer region is set to 0.55° or less.
  • the GAM value of the crystal grains in the inner region and the surface region is measured by the following method.
  • a sample is taken at a 1/4 position in the width direction from the end face of the hot-rolled steel sheet so that the metal structure of the cross section (thickness direction x rolling direction cross section) with the width direction as the normal direction can be observed.
  • the size of the sample depends on the measuring device, but it may be, for example, a rectangular parallelepiped with a total thickness in the thickness direction, 15 mm in the rolling direction, and 10 mm in the width direction.
  • the observation surface of the sample is mirror-polished, and then polished for 8 minutes at room temperature using colloidal silica that does not contain an alkaline solution to remove the strain introduced into the surface of the sample.
  • a region of 200 ⁇ m in the thickness direction and 400 ⁇ m or more at any position in the rolling direction (a rectangular region having a center at a 1/4 depth position in the thickness direction, a rectangular region having a length (short side) of 200 ⁇ m in the thickness direction and a length (long side) of 400 ⁇ m or more in the rolling direction) centered at a 1/4 depth position in the thickness direction from the surface of the sample after the above polishing is measured at a measurement interval of 0.2 ⁇ m to obtain crystal orientation information.
  • an EBSD analyzer consisting of a thermal field emission scanning electron microscope (JSM-7001F manufactured by JEOL) and an EBSD detector (HIKARI detector manufactured by TSL) is used.
  • the degree of vacuum in the EBSD analyzer is 9.6 ⁇ 10 ⁇ 5 Pa or less
  • the acceleration voltage is 15 kV
  • the irradiation current level is 13
  • the electron beam irradiation level is 62.
  • a region surrounded by grain boundaries with an orientation difference of 15° or more in the EBSD analysis image is regarded as one crystal grain using the “Grain Average Misorientation” function mounted on the software “OIM Analysis (registered trademark)” attached to the EBSD analyzer, and the GAM value of the crystal grain is obtained by calculating the average value of the orientation difference between adjacent pixels in the crystal grain.
  • crystal grains with a defined equivalent circle diameter of 0.6 ⁇ m or less are excluded from the measurement because there is a possibility of a large measurement error.
  • GAM value obtained, the area of the crystal grain measured in the EBSD analysis image, and the following formula (1) are used to perform a calculation for all crystal grains to obtain GAM I , which is the area average value of the GAM values of the crystal grains in the internal region.
  • GAM i represents the GAM value of the i-th crystal grain
  • Ai represents the area of the i-th crystal grain
  • n represents the number of crystal grains included in the measurement range.
  • GAM S is the area average value of the GAM values of the crystal grains in the surface layer region.
  • the standard deviation of the area average values of the GAM values of the crystal grains in the surface region is obtained by using the area average value GAM S of the GAM values obtained for the crystal grains in the surface region and the following formula (2).
  • GAM i represents the GAM value of the i-th crystal grain
  • Ai represents the area of the i-th crystal grain
  • n represents the number of crystal grains included in the measurement range.
  • the rolling direction of the hot-rolled steel sheet is determined by the following method.
  • a test piece is taken so that a cross section parallel to the plate surface of the hot-rolled steel sheet can be observed.
  • a cross section at a position where the distance from the surface is 1/4 of the plate thickness is mirror-polished and then observed using an optical microscope.
  • the observation range is 500 ⁇ m ⁇ 500 ⁇ m or more, and the direction parallel to the extension direction of the crystal grains is determined to be the rolling direction.
  • the direction perpendicular to the determined rolling direction is determined to be the width direction of the hot-rolled steel sheet.
  • the area ratio of the region where the GAM value is more than 0.6° is set to 50% or more.
  • the area ratio of the region where the GAM value is more than 0.6° is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more.
  • the area ratio of the region where the GAM value exceeds 0.6° may be set to 100%.
  • Sum of the area ratio of the region where the GAM value is more than 3.0° and the area ratio of the retained austenite less than 15% If the sum of the area ratio of the region where the GAM value is more than 3.0° and the area ratio of the retained austenite is 15% or more, the desired strength may not be obtained in the hot-rolled steel sheet, or the desired hole expandability may not be obtained. Therefore, the sum of the area ratio of the region where the GAM value is more than 3.0° and the area ratio of the retained austenite is less than 15%.
  • the sum of the area ratio of the region where the GAM value is more than 3.0° and the area ratio of the retained austenite is preferably 10% or less, more preferably 5% or less.
  • the sum of the area ratio of the region where the GAM value exceeds 3.0° and the area ratio of the retained austenite may be 0% or may be 1% or more.
  • the hot-rolled steel sheet according to this embodiment has the above-mentioned chemical composition and metal structure, and may have either the first or second type of metal structure described below, depending on the desired strength, ductility, and degree of bendability after pre-straining.
  • the first aspect is a metal structure suitable for cases where a higher level of strength and ductility is required.
  • the area ratio of the region where the GAM value is more than 0.6° and less than 2.0° is preferably 70% or more, more preferably 85% or more.
  • the area ratio of the region where the GAM value is more than 0.6° and less than 2.0° may be 100%.
  • the remaining structure other than the areas where the GAM value is greater than 0.6° and less than 2.0° may include areas where the GAM value is 2.0° or more and areas where the GAM value is 0.6° or less, with a total area ratio of 0 to 50%.
  • the second aspect is a metal structure suitable for cases where relatively higher strength is required.
  • the area ratio of the region where the GAM value is 2.0° or more is preferably 70% or more, more preferably 85% or more.
  • the area ratio of the region having a GAM value of 2.0° or more may be 100%.
  • the remaining structure other than the area where the GAM value is 2.0° or more may include an area ratio of 0 to 50% where the GAM value is less than 2.0°.
  • the area ratio of the region where the GAM value exceeds 0.6°, the area ratio of the region where the GAM value is greater than 0.6° and less than 2.0°, the area ratio of the region where the GAM value is 2.0° or more, and the area ratio of the region where the GAM value is greater than 3.0° are measured by the following method.
  • the GAM value of the crystal grains in the inner region is calculated by the same method as that used for measuring the GAM value of the crystal grains in the inner region.
  • the area ratio of the crystal grains having the obtained GAM value exceeding 0.6°, the area ratio of the crystal grains having the GAM value exceeding 0.6° and less than 2.0°, the area ratio of the crystal grains having the GAM value of 2.0° or more, and the area ratio of the region having the GAM value exceeding 3.0° are calculated to obtain the area ratio of each region.
  • the area ratio of retained austenite is measured by the following method.
  • a sample is taken so that the metal structure can be observed in a region of 1 mm or more at any position in the rolling direction and 1 mm or more from the end face in the cross section at 1/4 position in the sheet thickness direction from the surface of the hot-rolled steel sheet.
  • the sample is subjected to Co-K ⁇ radiation to obtain the integrated intensity of a total of six peaks, ⁇ (110), ⁇ (200), ⁇ (211), ⁇ (111), ⁇ (200), and ⁇ (220).
  • the volume ratio of retained austenite is calculated from the integrated intensity using the intensity averaging method.
  • the obtained volume ratio of retained austenite is regarded as the area ratio of retained austenite.
  • the tensile strength may be 940 MPa or more.
  • the upper limit of the tensile strength does not need to be particularly limited, but from the viewpoint of suppressing die wear, it may be 1400 MPa or less.
  • Uniform elongation 3.0% or more
  • the uniform elongation may be 3.0% or more.
  • it can be suitably applied to automobile parts.
  • the tensile strength and uniform elongation are measured by performing a tensile test in accordance with JIS Z 2241: 2022 using a No. 5 test piece of JIS Z 2241: 2022.
  • the tensile test piece is taken from the center position in the width direction, and the direction perpendicular to the rolling direction and the plate thickness direction (width direction) is defined as the longitudinal direction.
  • a minute test piece with the width direction as the longitudinal direction can be used instead as the test piece for measuring the tensile strength.
  • Hole expansion ratio 40% or more
  • the hole expansion ratio may be 40% or more. By setting the hole expansion ratio to 40% or more, it can be suitably applied to automobile parts. There is no need to particularly limit the upper limit of the hole expansion ratio, but it may be 80% or less.
  • the hole expansion ratio is measured by performing a hole expansion test in accordance with JIS Z 2256:2020.
  • Bendability after pre-straining is evaluated by performing a bending test on the hot-rolled steel sheet after the draw-bending process.
  • the draw-bending process is performed, for example, by forming the hat part 10 with a forming height of 60 mm under the conditions shown in FIG. 1.
  • the test piece is taken from the hot-rolled steel sheet so that the longitudinal direction of the test piece is the width direction of the hot-rolled steel sheet and the test piece is 240 mm x 60 mm.
  • the conditions of the draw-bending process are as follows: the width of the punch 1 is 75 mm, the corner R of the punch 1 is "sheet thickness x 5 (mm)", the corner R of the die 2 is “sheet thickness x 3.125 mm”, the clearance between the punch 1 and the die 2 is “sheet thickness + 0.9 mm”, and the blank holder force (BHF) is "sheet thickness x 6.25 (ton)".
  • the conditions shown in FIG. 1 are the conditions when the sheet thickness is 1.6 mm.
  • the steel plate comes into contact with the punch 1 while undergoing bending and unbending deformation as the vertical wall 11 is formed, so that the recess formed in the flat-R part near the vertical wall of the automobile suspension part can be reproduced.
  • a test piece is taken from the vertical wall 11 of the hat part 10 so that the die 2 side is on the outside of the bend and the stroke direction D of the punch 1 is the bending axis direction.
  • the bending test is performed using the above-mentioned test piece under the following conditions based on the VDA standard (VDA238-100) specified by the German Association of the Automotive Industry.
  • VDA238-100 the tensile strength of a hot-rolled steel sheet
  • the maximum bending angle obtained in a bending test after pre-straining is 70° or more, it can be determined that the sheet has excellent bendability after pre-straining.
  • the tensile strength of a hot-rolled steel sheet is 1040 MPa or more, if the maximum bending angle obtained in a bending test after pre-straining is 50° or more, it can be determined that the sheet has excellent bendability after pre-straining.
  • the thickness of the test piece after the prestrain is more than 1.6 mm, the surface on the punch side is ground to make the thickness 1.6 mm before the bending test.
  • the maximum bending angle obtained by the following formula is adopted, where ⁇ 0 represents the maximum bending angle obtained by the bending test, t represents the plate thickness, and uEL represents the uniform elongation.
  • Maximum bending angle when 1.6 mm or less ⁇ 0 -13.852 x (1 - t / 1.6) x (uEL + 0.22) 0.292
  • Test piece dimensions 60 mm (rolling direction) x 30 mm (width direction)
  • Test piece thickness 1.6 mm Bending ridge: Parallel to the width direction
  • Test method Roll support, punch pressing Roll diameter: ⁇ 30 mm
  • Punch shape: Tip R 0.4 mm Distance between rolls: 2.0 x plate thickness (mm) + 0.5 mm
  • each embodiment may have the following strength, ductility, and bendability after prestrain. Note that the desired hole expansion property is the same in both embodiments, so the explanation is omitted.
  • Tensile strength 940 MPa or more, uniform elongation: 4.0% or more
  • the tensile strength may be 940 MPa or more
  • the uniform elongation may be 4.0% or more
  • the tensile strength may be 980 MPa or more.
  • the uniform elongation may be 5.0% or more.
  • Tensile strength 1040 MPa or more, uniform elongation: 3.0% or more
  • the tensile strength may be 1040 MPa or more, and the uniform elongation may be 3.0% or more.
  • the tensile strength may be 1140 MPa or more.
  • the uniform elongation may be 4.0% or more.
  • the hot-rolled steel sheet according to this embodiment may be provided with a plating layer on the surface for the purpose of improving corrosion resistance, etc., to form a surface-treated steel sheet.
  • the plating layer may be an electroplating layer or a hot-dip plating layer.
  • electroplating layers include electrogalvanizing and electrogalvanizing Zn-Ni alloy plating.
  • hot-dip plating layers include hot-dip galvanizing, alloyed hot-dip galvanizing, hot-dip aluminum plating, hot-dip Zn-Al alloy plating, hot-dip Zn-Al-Mg alloy plating, and hot-dip Zn-Al-Mg-Si alloy plating.
  • an appropriate chemical conversion treatment for example, applying a silicate-based chromium-free chemical conversion treatment solution and drying
  • the hot-rolled steel sheet according to this embodiment can be stably manufactured.
  • the temperature of the slab and the temperature of the steel sheet in this embodiment refer to the surface temperature of the slab and the surface temperature of the steel sheet.
  • Steps (1) to (3) described below are common to the first and second aspects. As for the subsequent steps, steps (4) and (5) correspond to the first aspect, and step (6) corresponds to the second aspect.
  • a preferred method for producing a hot-rolled steel sheet according to this embodiment is as follows: (1) Before rough rolling, a slab having the above-mentioned chemical composition is subjected to two or more strains in the width direction, the difference between the temperature at the time of the first strain application and the temperature at the time of the final strain application is set to 20 to 40 ° C., and descaling is performed every time a strain is applied in the width direction; (2) performing rough rolling on the strained slab; (3) performing finish rolling so that the difference between the finish rolling start temperature and the finish rolling completion temperature is 60° C. or more and less than 120° C., and the finish rolling completion temperature is 950° C. or less; Furthermore, the method includes one or more of the following steps (4) to (6).
  • Imparting strain before rough rolling common to the first and second aspects Before rough rolling, it is preferable to impart strain to a slab having the above-mentioned chemical composition two or more times in the width direction, and the difference between the temperature at the time of the first width direction strain imparting and the temperature at the time of the final width direction strain imparting is 20 to 40 ° C. This makes it possible to control the non-uniformity in the surface layer region to an appropriate state. As a result, it is possible to control the standard deviation of the area average value of the GAM value of the crystal grains in the surface layer region of the hot-rolled steel sheet to a preferred range.
  • the "width direction of the slab” is a direction perpendicular to the slab transport direction and the plate thickness direction, and the slab transport direction corresponds to the rolling direction in the subsequent process.
  • strain is applied in the width direction two or more times.
  • the difference in temperature between the first strain application and the final strain application can be preferably controlled to 20 to 40°C.
  • the strain may be imparted after the slab is heated for rough rolling.
  • a method for imparting strain in the width direction of a slab includes, for example, passing the slab between rolls whose rotation axes are perpendicular to the plate surface and conveying direction of the slab to impart strain in the width direction to the slab (pressing down in the width direction).
  • the slab to which strain is applied is not particularly limited except for the chemical composition described above.
  • a slab produced by melting molten steel of the above chemical composition using a converter or electric furnace, etc. and then by continuous casting can be used.
  • an ingot casting method, thin slab casting method, etc. may be used.
  • the heating temperature may be in the range of 1100 to 1300°C.
  • Rough rolling common to the first and second aspects
  • the conditions of rough rolling are not particularly limited, and the rough rolling can be, for example, a process in which rolling is performed multiple times at a temperature of 1100 ° C. or higher to reduce the plate thickness to 30 to 60 mm.
  • finish rolling common to the first and second aspects
  • the finish rolling completion temperature delivery temperature
  • the finish rolling completion temperature is 950°C or less.
  • GAM S /GAM I which is the ratio of GAM I, which is the area average value of the GAM value of the crystal grains in the inner region
  • GAM S which is the area average value of the GAM value of the crystal grains in the surface layer region
  • the lower limit of the finish rolling completion temperature is not particularly limited, and may be appropriately determined according to the rolling load limit of the equipment. In order to suppress a sudden increase in load, the finish rolling completion temperature may be, for example, 850°C or more.
  • Slow cooling (air cooling) in a temperature range of 580 to 680°C corresponds to the first embodiment. After the completion of finish rolling, accelerated cooling is performed to a temperature range of 580 to 680°C at an average cooling rate of 30°C/s or more, and slow cooling (air cooling) is performed in this temperature range for 2.0 seconds or more.
  • slow cooling air cooling
  • the area ratio of the region where the GAM value is more than 0.6° and less than 2.0° can be increased.
  • slow cooling (air cooling) refers to cooling at an average cooling rate of 20° C./s or less.
  • Slow cooling (air cooling) followed by accelerated cooling corresponds to the first embodiment After slow cooling (air cooling) in the temperature range of 580 to 680° C. (first embodiment), accelerated cooling is performed at an average cooling rate of 30° C./s or more until the temperature reaches 300° C. By performing accelerated cooling at an average cooling rate of 30° C./s or more until the temperature reaches 300° C. after slow cooling (air cooling), a desired metal structure can be obtained. After accelerated cooling to 300° C., the wire may be left to cool to room temperature or may be wound into a coil and then water-cooled.
  • Accelerated cooling down to 300° C. Corresponding to the second embodiment After the completion of finish rolling, accelerated cooling is performed at an average cooling rate of 30° C./s or more down to 300° C. By performing accelerated cooling down to 300° C. at an average cooling rate of 30° C./s or more without performing slow cooling (air cooling) during the accelerated cooling, it is possible to increase the area ratio of the region where the GAM value exceeds 0.6° (including the region where the GAM value is 2.0° or more). After accelerated cooling to 300° C., the wire may be left to cool to room temperature or may be wound into a coil and then water-cooled.
  • the average cooling rate is the temperature difference between the start and end points of the set range divided by the elapsed time from the start point to the end point.
  • the conditions in the embodiment are merely an example of conditions adopted to confirm the feasibility and effects of the present invention, and the present invention is not limited to this example of conditions.
  • Various conditions may be adopted in the present invention as long as they do not deviate from the gist of the present invention and achieve the object of the present invention.
  • the "Temperature difference when applying width direction strain” column in the table shows the difference in temperature between the temperature when the first width direction strain was applied and the temperature when the final width direction strain was applied.
  • the obtained hot-rolled steel sheets were evaluated for metal structure, tensile strength (TS), uniform elongation (uEl), hole expansion ratio ( ⁇ ) and bendability after pre-straining by the above-mentioned methods.
  • the results obtained are shown in Tables 4A to 5C.
  • TS tensile strength
  • the hole expansion ratio ( ⁇ ) was 40% or more, it was judged to have excellent hole expansion properties and to pass. On the other hand, if the hole expansion ratio ( ⁇ ) was less than 40%, it was judged to have no excellent hole expansion properties and to fail.
  • the bendability (maximum bending angle) after the prestrain was applied was evaluated according to the following criteria in accordance with the tensile strength.
  • the tensile strength was less than 1040 MPa
  • the bendability (maximum bending angle) after prestraining was 70° or more
  • the specimen was judged as having excellent bendability after prestraining and was passed.
  • the bendability (maximum bending angle) after prestraining was less than 70°, the specimen was judged as not having excellent bendability after prestraining and was passed.
  • the hot-rolled steel sheets according to the examples of the present invention have high strength, as well as excellent ductility and hole expandability, and also have excellent bendability after pre-straining.
  • the steel sheets according to the comparative examples are inferior in at least one of the characteristics.
  • the above-mentioned aspects of the present invention provide a hot-rolled steel sheet that has high strength, excellent ductility and hole expansion properties, as well as excellent bendability after pre-straining.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Abstract

La tôle d'acier laminée à chaud selon la présente invention a une composition chimique prescrite, et GAMS/GAMI est de 0,70 à 1,05. Dans la structure métallique au niveau d'un emplacement à une profondeur de 1/4 à partir de la surface dans la direction de l'épaisseur de la feuille, le rapport de surface d'une région dans laquelle la valeur GAM est supérieure à 0,6° est de 50 % ou plus, le total du rapport de surface d'une région dans laquelle la valeur GAM est supérieure à 3,0° et du rapport de surface de l'austénite résiduelle est inférieur à 15 %, et l'écart-type de la valeur moyenne de surface de la valeur GAM des grains cristallins dans une région depuis la surface à une profondeur de 200 µm dans la direction de l'épaisseur de la feuille est de 0,25 à 0,65°.
PCT/JP2024/003020 2023-01-31 2024-01-31 Tôle d'acier laminée à chaud Ceased WO2024162381A1 (fr)

Priority Applications (5)

Application Number Priority Date Filing Date Title
CN202480008616.5A CN120569506A (zh) 2023-01-31 2024-01-31 热轧钢板
KR1020257022668A KR20250118850A (ko) 2023-01-31 2024-01-31 열연 강판
JP2024574966A JPWO2024162381A1 (fr) 2023-01-31 2024-01-31
EP24750330.3A EP4660342A1 (fr) 2023-01-31 2024-01-31 Tôle d'acier laminée à chaud
MX2025008622A MX2025008622A (es) 2023-01-31 2025-07-23 Lamina de acero laminada en caliente

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JP2023-013129 2023-01-31
JP2023013129 2023-01-31

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JP (1) JPWO2024162381A1 (fr)
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CN (1) CN120569506A (fr)
MX (1) MX2025008622A (fr)
WO (1) WO2024162381A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003321725A (ja) 2002-04-26 2003-11-14 Jfe Steel Kk 高強度鋼板及びその製造方法
WO2018138898A1 (fr) * 2017-01-30 2018-08-02 新日鐵住金株式会社 Plaque d'acier
WO2021124864A1 (fr) * 2019-12-19 2021-06-24 日本製鉄株式会社 Tôle d'acier et tôle d'acier plaquée
WO2022070608A1 (fr) * 2020-09-30 2022-04-07 日本製鉄株式会社 Tôle d'acier et procédé de fabrication de tôle d'acier
JP2023013129A (ja) 2021-07-15 2023-01-26 株式会社マキタ 運搬車
WO2023171492A1 (fr) * 2022-03-11 2023-09-14 日本製鉄株式会社 Article formé par estampage à chaud

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003321725A (ja) 2002-04-26 2003-11-14 Jfe Steel Kk 高強度鋼板及びその製造方法
WO2018138898A1 (fr) * 2017-01-30 2018-08-02 新日鐵住金株式会社 Plaque d'acier
WO2021124864A1 (fr) * 2019-12-19 2021-06-24 日本製鉄株式会社 Tôle d'acier et tôle d'acier plaquée
WO2022070608A1 (fr) * 2020-09-30 2022-04-07 日本製鉄株式会社 Tôle d'acier et procédé de fabrication de tôle d'acier
JP2023013129A (ja) 2021-07-15 2023-01-26 株式会社マキタ 運搬車
WO2023171492A1 (fr) * 2022-03-11 2023-09-14 日本製鉄株式会社 Article formé par estampage à chaud

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP4660342A1

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CN120569506A (zh) 2025-08-29
MX2025008622A (es) 2025-08-01
JPWO2024162381A1 (fr) 2024-08-08
KR20250118850A (ko) 2025-08-06
EP4660342A1 (fr) 2025-12-10

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