WO2022239071A1 - 亜鉛系めっき鋼板 - Google Patents
亜鉛系めっき鋼板 Download PDFInfo
- Publication number
- WO2022239071A1 WO2022239071A1 PCT/JP2021/017739 JP2021017739W WO2022239071A1 WO 2022239071 A1 WO2022239071 A1 WO 2022239071A1 JP 2021017739 W JP2021017739 W JP 2021017739W WO 2022239071 A1 WO2022239071 A1 WO 2022239071A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- steel sheet
- thickness
- less
- layer
- zinc
- Prior art date
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- 229910001335 Galvanized steel Inorganic materials 0.000 title claims abstract description 23
- 239000008397 galvanized steel Substances 0.000 title claims abstract description 23
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 323
- 239000010959 steel Substances 0.000 claims abstract description 323
- 239000010410 layer Substances 0.000 claims description 276
- 239000011701 zinc Substances 0.000 claims description 123
- 229910052725 zinc Inorganic materials 0.000 claims description 110
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 109
- 238000007747 plating Methods 0.000 claims description 105
- 239000000203 mixture Substances 0.000 claims description 41
- 239000000126 substance Substances 0.000 claims description 20
- 239000011247 coating layer Substances 0.000 claims description 18
- 239000012535 impurity Substances 0.000 claims description 13
- 229910052782 aluminium Inorganic materials 0.000 claims description 8
- 239000011248 coating agent Substances 0.000 claims description 8
- 238000000576 coating method Methods 0.000 claims description 8
- 229910052721 tungsten Inorganic materials 0.000 claims description 4
- 239000011572 manganese Substances 0.000 description 58
- 238000005098 hot rolling Methods 0.000 description 56
- 238000000137 annealing Methods 0.000 description 53
- 238000000034 method Methods 0.000 description 52
- 238000000227 grinding Methods 0.000 description 33
- 230000008569 process Effects 0.000 description 33
- 238000005275 alloying Methods 0.000 description 27
- 230000015572 biosynthetic process Effects 0.000 description 21
- 229910052760 oxygen Inorganic materials 0.000 description 20
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 19
- 238000004519 manufacturing process Methods 0.000 description 19
- 239000001301 oxygen Substances 0.000 description 19
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 18
- 238000005097 cold rolling Methods 0.000 description 17
- 230000003647 oxidation Effects 0.000 description 17
- 238000007254 oxidation reaction Methods 0.000 description 17
- 230000000694 effects Effects 0.000 description 16
- 239000010960 cold rolled steel Substances 0.000 description 15
- 238000004544 sputter deposition Methods 0.000 description 15
- 230000006866 deterioration Effects 0.000 description 14
- 238000005259 measurement Methods 0.000 description 14
- 229910052799 carbon Inorganic materials 0.000 description 13
- 238000005246 galvanizing Methods 0.000 description 13
- 230000009467 reduction Effects 0.000 description 13
- 238000005096 rolling process Methods 0.000 description 13
- 229910052710 silicon Inorganic materials 0.000 description 13
- 239000010687 lubricating oil Substances 0.000 description 12
- 229910052748 manganese Inorganic materials 0.000 description 12
- 229910052761 rare earth metal Inorganic materials 0.000 description 12
- 238000009864 tensile test Methods 0.000 description 12
- 239000011575 calcium Substances 0.000 description 11
- 238000005554 pickling Methods 0.000 description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 10
- 230000007423 decrease Effects 0.000 description 10
- 230000007797 corrosion Effects 0.000 description 9
- 238000005260 corrosion Methods 0.000 description 9
- 238000005261 decarburization Methods 0.000 description 9
- 238000009826 distribution Methods 0.000 description 9
- 239000011777 magnesium Substances 0.000 description 9
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 9
- 239000011651 chromium Substances 0.000 description 8
- 239000010949 copper Substances 0.000 description 8
- 238000011156 evaluation Methods 0.000 description 8
- 239000010955 niobium Substances 0.000 description 8
- 239000010936 titanium Substances 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- 238000005266 casting Methods 0.000 description 7
- 229910052739 hydrogen Inorganic materials 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 6
- 239000003112 inhibitor Substances 0.000 description 6
- 239000002344 surface layer Substances 0.000 description 6
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- 238000001816 cooling Methods 0.000 description 5
- 239000006185 dispersion Substances 0.000 description 5
- 230000006872 improvement Effects 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 210000003660 reticulum Anatomy 0.000 description 5
- 238000012935 Averaging Methods 0.000 description 4
- 229910052796 boron Inorganic materials 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 238000003303 reheating Methods 0.000 description 4
- 238000003860 storage Methods 0.000 description 4
- 230000003746 surface roughness Effects 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000003723 Smelting Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 239000004566 building material Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 229910052735 hafnium Inorganic materials 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 238000009616 inductively coupled plasma Methods 0.000 description 2
- 238000001095 inductively coupled plasma mass spectrometry Methods 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 239000013585 weight reducing agent Substances 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910001208 Crucible steel Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 229910001122 Mischmetal Inorganic materials 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 229910004283 SiO 4 Inorganic materials 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 229910052747 lanthanoid Inorganic materials 0.000 description 1
- 150000002602 lanthanoids Chemical class 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 238000004020 luminiscence type Methods 0.000 description 1
- VASIZKWUTCETSD-UHFFFAOYSA-N manganese(II) oxide Inorganic materials [Mn]=O VASIZKWUTCETSD-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
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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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
- C21D1/76—Adjusting the composition of the atmosphere
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
- C23C2/36—Elongated material
- C23C2/40—Plates; Strips
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B15/00—Layered products comprising a layer of metal
- B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
- B32B15/013—Layered products comprising a layer of metal all layers being exclusively metallic one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or aluminium
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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
- C21D3/00—Diffusion processes for extraction of non-metals; Furnaces therefor
- C21D3/02—Extraction of non-metals
- C21D3/04—Decarburising
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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
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- C21D6/001—Heat treatment of ferrous alloys containing Ni
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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
- C21D6/002—Heat treatment of ferrous alloys containing Cr
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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
- C21D6/005—Heat treatment of ferrous alloys containing Mn
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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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- 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
- 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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- 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
- 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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- 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
- 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
- C21D8/0236—Cold rolling
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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
- 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
- C21D8/0257—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment with diffusion of elements, e.g. decarburising, nitriding
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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
- 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
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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
- 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
- C21D8/0273—Final recrystallisation annealing
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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
- 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
- C21D8/0278—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular surface treatment
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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- C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
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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
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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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
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
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- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
- C23C2/06—Zinc or cadmium or alloys based thereon
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- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/26—After-treatment
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- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/26—After-treatment
- C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/26—After-treatment
- C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
- C23C2/29—Cooling or quenching
Definitions
- the present invention relates to zinc-based plated steel sheets. More specifically, the present invention relates to a thin and high-strength zinc-based plated steel sheet with excellent appearance properties.
- parts such as doors, bonnets, and roofs have a much larger surface area than structural parts such as pillars.
- the sheet thickness becomes thin and the sheet width becomes very large.
- such members occupy a large part of the exterior of automobiles, they are required not only to have high strength but also to have an excellent appearance.
- the high-strength steel sheet has a coating layer such as a hot-dip galvanized layer or an alloyed hot-dip galvanized layer formed on the surface from the viewpoint of improving corrosion resistance.
- a coating layer such as a hot-dip galvanized layer or an alloyed hot-dip galvanized layer formed on the surface from the viewpoint of improving corrosion resistance.
- the steel sheet typically cold-rolled steel sheet
- Patent Documents 1 to 4 teach that an annealing step is or may be performed before the plating step in order to manufacture each of the plated steel sheets described in Patent Documents 1 to 4.
- Si and Mn which are elements with a strong affinity for oxygen, combine with oxygen in the atmosphere during the annealing process to form a layer containing oxides near the surface of the steel sheet.
- the form of such a layer includes a form in which an oxide containing Si or Mn is formed as a film on the outside (surface) of the steel sheet (external oxidation), and a form in which an oxide is formed inside the steel sheet (surface layer). (internal oxidation).
- a zinc-based coating layer for example, a hot-dip galvanized layer or an alloyed hot-dip galvanized layer
- the oxide exists as a film on the surface of the steel sheet.
- interdiffusion of steel components (eg Fe) and plating components (eg Zn) is inhibited.
- the reaction between the steel and the plated layer may be adversely affected, resulting in insufficient plateability (for example, increased unplated portions). If so, there is a risk that the appearance properties and rust prevention performance of the plated steel sheet will deteriorate.
- these oxides affect the Fe—Zn reaction rate when alloying the plating layer, and as a result, the plating properties may become insufficient (for example, uneven alloying may occur). Even in such a case, the appearance properties of the plated steel sheet may deteriorate. Therefore, from the viewpoint of improving plateability and obtaining a plated steel sheet with good appearance properties, a steel sheet having an internal oxide layer in which oxides exist inside is better than a steel sheet having an external oxide layer. preferable.
- Decarburization means that carbon near the surface of the steel sheet combines with oxygen in the annealing atmosphere to form CO 2 and is released outside the system, and the region lacking carbon is called a decarburized layer. Since carbon in steel is an element that contributes to the strength of the steel, a thick decarburized layer reduces the strength near the surface of the steel sheet. The decrease in the strength of the steel sheet surface due to the presence of such a decarburized layer does not pose a particular problem when the thickness of the zinc-based plated steel sheet is relatively small because the degree of influence thereof is relatively small. However, in the case of a zinc-based plated steel sheet having a very thin sheet thickness, the effect of strength reduction due to decarburization cannot be ignored.
- the present inventors have found that, in zinc-based steel sheets having a steel sheet thickness of 0.10 to 0.95 mm, the ratio of the thickness of the internal oxide layer to the thickness of the decarburized layer on the surface of the steel sheet, and the thickness of the decarburized layer and the steel sheet It has been found that both high strength and high plating properties can be achieved by strictly controlling the ratio of the thickness to the plate thickness.
- the present invention was made based on the above findings, and the gist thereof is as follows.
- the width of the steel sheet is 1500 to 3000 mm, and the standard deviation in the width direction of the thickness of the internal oxide layer: a ( ⁇ m) and the standard deviation in the thickness of the decarburized layer in the width direction: b ( ⁇ m).
- A 1.0 ⁇ m or more
- B 10 ⁇ m or more
- a/A 0.15 or less
- the steel plate in % by mass, B: 0.0001 to 0.0100%, Ti: 0.001 to 0.100%, Nb: 0.001 to 0.100%, Cr: 0.01 to 1.00%, Mo: 0.01-0.50%, and W: 0.01-0.50%
- the zinc-based plated steel sheet according to any one of (1) to (3) which has a chemical composition containing one or more of (5)
- the steel plate in % by mass, V: 0.01 to 0.10%, Ni: 0.01 to 0.10%, Cu: 0.01 to 0.10%, Ca: 0.001 to 0.100%, Mg: 0.001-0.100%, Zr: 0.001 to 0.100%, Hf: 0.001-0.100%, and REM: 0.001-0.100%
- the zinc-based plated steel sheet is an alloyed hot-dip galvanized steel sheet, and the component composition of the zinc-based
- a zinc-based plated steel sheet having a thickness of 0.10 to 0.95 mm, which is capable of achieving both sufficient strength and plateability.
- An excellent thin and high-strength galvanized steel sheet can be obtained.
- FIG. 4 is a diagram for explaining a method for measuring the thickness of a decarburized layer in the present invention.
- zinc-based plated steel sheets used for automobile members are generally produced by hot-rolling and cold-rolling a steel billet having a predetermined chemical composition of C, Si, Mn, etc., followed by annealing.
- Manufactured by zinc-based plating and, if necessary, alloying are appropriately controlled in order to form a zinc-based plating layer without unplated portions and/or to reduce uneven alloying (unevenness in appearance after alloying treatment).
- the oxide inside the steel sheet in the zinc-based plating treatment, the interdiffusion of the steel component (e.g., Fe) and the plating component (e.g., Zn) occurs well, and the zinc-based plating layer is formed without unplated portions. It is formed satisfactorily, and it becomes possible to reduce alloying unevenness when alloying, and the plating property is improved. As a result, a zinc-based plated steel sheet having excellent appearance properties can be obtained. Therefore, it is effective to control the annealing conditions to form an internal oxide layer on the surface layer of the steel sheet in order to ensure sufficient plating properties in the zinc-based plated steel sheet.
- the steel component e.g., Fe
- the plating component e.g., Zn
- a decarburized layer is usually formed near the surface of the steel sheet. Since the decarburized layer lacks carbon that greatly contributes to the strength of the steel sheet, the presence of the decarburized layer reduces the strength near the surface of the steel sheet. When a zinc-based plated steel sheet is used for a relatively thick member, the decarburized layer does not significantly reduce strength. However, in the case of thin members, such as doors, bonnets, roofs, and other automotive parts, zinc-based plated steel sheets are greatly affected by a decrease in strength due to the decarburized layer, and control of the thickness of the decarburized layer is extremely important.
- an internal oxide layer is formed from the viewpoint of obtaining good plating properties (appearance properties), and from the viewpoint of ensuring strength. It is preferable to achieve compatibility with thinning the thickness of the coal bed.
- the present inventors conducted various studies to achieve both high strength and high plateability in a zinc-based plated steel sheet having a thickness of 0.10 to 0.95 mm.
- C, Mn, Si and Al are added in predetermined amounts or more, and the ratio of the thickness of the internal oxide layer on the surface of the steel sheet to the thickness of the decarburized layer and the thickness of the decarburized layer to the thickness of the steel sheet are strictly controlled. It was found that it is effective to control. More specifically, the inventors determined the thickness of the internal oxide layer per side of the steel sheet: A ( ⁇ m), the thickness of the decarburized layer per side of the steel sheet: B ( ⁇ m), and the thickness of the steel sheet. When t ( ⁇ m), A / B is in the range of 0.01 to 0.50, and B / t is in the range of 0.001 to 0.200 to ensure plating properties and strength. found to be important for
- a zinc-based plated steel sheet according to the present invention includes a steel sheet and a zinc-based plating layer formed on at least one side of the steel sheet. Therefore, the zinc-based plating layer may be formed on one side or both sides of the steel sheet. Moreover, in the present invention, the zinc-based plating layer may be formed on the steel sheet, and another plating layer may be provided between the steel sheet and the zinc-based plating layer. As will be described later, the zinc-based plating layer refers to a plating layer containing zinc, such as a hot-dip galvanized layer and an alloyed hot-dip galvanized layer.
- C (C: 0.05-0.30%) C (carbon) is an important element for ensuring the strength of the galvanized steel sheet. If the C content is insufficient, there is a possibility that sufficient strength cannot be secured. Therefore, the C content is 0.05% or more, preferably 0.07% or more, more preferably 0.08% or more, and still more preferably 0.10% or more. On the other hand, if the C content is excessive, the strength may become excessively high and the weldability may deteriorate. Therefore, the C content is 0.30% or less, preferably 0.25% or less, more preferably 0.20% or less.
- Si 0.01 to 3.00%
- Si silicon
- Si is an effective element for improving the strength of the steel sheet.
- Si is one of the elements that combine with oxygen during annealing to form internal oxides.
- Si is also an element that affects plating properties and alloying speed. If the Si content is insufficient, internal oxidation may not be sufficiently generated. Therefore, the Si content is 0.01% or more, preferably 0.03% or more or 0.05% or more, more preferably 0.10% or more or 0.30% or more. On the other hand, if the Si content is excessive, it may cause deterioration of the surface properties and lead to poor appearance.
- a Si-based oxide film (external oxide layer) may be formed on the surface of the steel sheet. Therefore, the Si content is 3.00% or less, preferably 2.50% or less, more preferably 2.00% or less.
- Mn manganese
- Mn manganese
- Mn is an element effective in improving the strength of a steel sheet by obtaining a hard structure. Mn is also one of the elements that combine with oxygen to form internal oxides during annealing. If the Mn content is insufficient, there is a possibility that sufficient strength cannot be secured. Therefore, the Mn content is 0.80% or more, preferably 1.00% or more, more preferably 1.20% or more. On the other hand, if Mn is excessively added, Mn segregation may make the metallographic structure non-uniform and workability may deteriorate. Therefore, the Mn content is 3.00% or less, preferably 2.80% or less, more preferably 2.50% or less.
- the sum of the Si content and the Mn content (Si + Mn) is set to 5.00% or less from the viewpoint of further suppressing the formation of the outer oxide layer and promoting the formation of the inner oxide layer. preferably 4.80% or less, more preferably 4.50% or less.
- the lower limit of Si+Mn is not particularly limited, for example, Si+Mn may be 0.81% or more, 0.90% or more, 1.00% or more, or 1.20% or more.
- the ratio of the Si content to the Mn content is preferably 1.50 or less, and preferably 1.20 or less. more preferred. While Si and Mn contribute to the improvement of the strength of steel, excessive content may deteriorate the appearance properties, and the effect on the appearance properties is more pronounced for Si than for Mn. be. Therefore, from the viewpoint of strength and formation of internal oxides, by containing a predetermined amount or more of Si and Mn and reducing the Si/Mn ratio, it is possible to maintain a better appearance. Although the lower limit of Si/Mn is not particularly limited, Si/Mn may be, for example, 0.01 or more, 0.03 or more, or 0.10 or more. Al is an element that can be substituted for Si, but when Al is added as a substitute for Si, it is not necessary to consider the Al content in the above sum and ratio.
- Al 0.010 to 2.000%
- Al aluminum
- Al is an element that acts as a deoxidizing element. If the Al content is less than 0.010%, a sufficient deoxidizing effect may not be obtained. Therefore, the Al content is 0.010% or more, preferably 0.100% or more, more preferably 0.200% or more. On the other hand, if Al is contained excessively, there is a risk of causing deterioration in workability and surface properties. Therefore, the Al content is 2.000% or less, preferably 1.500% or less, more preferably 1.000% or less.
- P phosphorus
- the P content is 0.100% or less, preferably 0.080% or less, more preferably 0.050% or less, still more preferably 0.020% or less.
- the lower limit of the P content is not particularly limited, but from the viewpoint of manufacturing costs, the P content may be more than 0% or 0.001% or more.
- S (sulfur) is an impurity generally contained in steel. If the S content exceeds 0.100%, the weldability is lowered, and furthermore, the amount of precipitation of MnS increases, which may lead to a decrease in workability such as bendability. Therefore, the S content is 0.100% or less, preferably 0.080% or less, more preferably 0.050% or less, still more preferably 0.020% or less.
- the lower limit of the S content is not particularly limited, but from the viewpoint of desulfurization cost, the S content may be more than 0% or 0.001% or more.
- N nitrogen
- nitrogen is an impurity generally contained in steel. If the N content exceeds 0.0300%, weldability may deteriorate. Therefore, the N content is 0.0300% or less, preferably 0.0200% or less, more preferably 0.0100% or less, still more preferably 0.0050% or less. Although the lower limit of the N content is not particularly limited, the N content may be more than 0% or 0.0010% or more from the viewpoint of manufacturing cost.
- O oxygen
- oxygen is an impurity generally contained in steel. If the O content exceeds 0.010%, ductility may deteriorate. Therefore, the O content is 0.010% or less, preferably 0.008% or less, more preferably 0.006% or less, still more preferably 0.005% or less. Although the lower limit of the O content is not particularly limited, the O content may be more than 0% or 0.001% or more from the viewpoint of production cost.
- the steel sheet in the present invention may contain optional elements described below as necessary.
- B (boron) is an element that increases hardenability and contributes to strength improvement, and is an element that segregates at grain boundaries to strengthen grain boundaries and improve toughness, so it may be contained as necessary. . Therefore, the B content is 0% or more, preferably 0.0001% or more, more preferably 0.0010% or more, still more preferably 0.0020% or more. On the other hand, from the viewpoint of ensuring sufficient toughness and weldability, the B content is 0.0100% or less, preferably 0.0090% or less, more preferably 0.0080% or less.
- Ti titanium
- Ti titanium
- the Ti content is 0% or more, preferably 0.001% or more, more preferably 0.010% or more, and still more preferably 0.020% or more.
- coarse TiN may be generated and the toughness may be impaired, so the Ti content is 0.100% or less, preferably 0.090% or less, more preferably 0.080% or less.
- Nb 0 to 0.100%
- Nb niobium
- the Nb content is 0% or more, preferably 0.001% or more, more preferably 0.010% or more, still more preferably 0.020% or more.
- the Nb content is 0.100% or less, preferably 0.090% or less, more preferably 0.080% or less.
- V vanadium
- V vanadium
- the V content is 0% or more, preferably 0.01% or more, more preferably 0.02% or more, and still more preferably 0.03% or more.
- the V content is 0.10% or less, preferably 0.09% or less, and more preferably 0.08% or less.
- Cr Cr (chromium) is an element that contributes to improving the strength and corrosion resistance of steel, so it may be contained as necessary. Therefore, the Cr content is 0% or more, preferably 0.01% or more, more preferably 0.05% or more, and still more preferably 0.10% or more. On the other hand, if it is contained excessively, a large amount of Cr carbide is formed, and there is a possibility that the hardenability may be impaired. % or less, more preferably 0.60% or less.
- Ni (Ni: 0 to 0.10%)
- Ni (nickel) is an element that contributes to improving the strength and corrosion resistance of steel, so it may be contained as necessary. Therefore, the Ni content is 0% or more, preferably 0.01% or more, and more preferably 0.02% or more. On the other hand, the Ni content is 0.10% or less, preferably 0.08% or less, from the viewpoint of production cost and the like.
- Cu (copper) is an element that contributes to improving the strength and corrosion resistance of steel, so it may be contained as necessary. Therefore, the Cu content is 0% or more, preferably 0.01% or more, and more preferably 0.02% or more. On the other hand, the Cu content is 0.10% or less, preferably 0.08% or less, from the viewpoint of suppressing deterioration of toughness, cracking of the slab after casting, and deterioration of weldability.
- Mo mobdenum
- Mo mobdenum
- the Mo content is 0% or more, preferably 0.01% or more, more preferably 0.10% or more.
- the Mo content is 0.50% or less, preferably 0.40% or less, and more preferably 0.30% or less.
- W tungsten
- the W content is 0% or more, preferably 0.01% or more, more preferably 0.05% or more, and still more preferably 0.10% or more.
- the W content is 0.50% or less, preferably 0.40% or less, more preferably 0.30% or less.
- Ca (Ca: 0 to 0.100%)
- Ca (calcium) is an element that contributes to the control of inclusions, particularly the fine dispersion of inclusions, and has the effect of increasing the toughness, so it may be contained as necessary. Therefore, the Ca content is 0% or more, preferably 0.001% or more, more preferably 0.005% or more, still more preferably 0.010% or more, and even more preferably 0.020% or more. On the other hand, if the Ca content is excessive, deterioration of the surface properties may become apparent, so the Ca content is 0.100% or less, preferably 0.080% or less, and more preferably 0.050% or less.
- Mg manganesium
- Mg is an element that contributes to the control of inclusions, particularly the fine dispersion of inclusions, and has the effect of increasing the toughness, so it may be contained as necessary. Therefore, the Mg content is 0% or more, preferably 0.001% or more, more preferably 0.003% or more, and still more preferably 0.010% or more. On the other hand, if the Mg content is excessive, deterioration of the surface properties may become apparent, so the Mg content is 0.100% or less, preferably 0.090% or less, and more preferably 0.080% or less.
- Zr zirconium
- the Zr content is 0% or more, preferably 0.001% or more, more preferably 0.005% or more, and still more preferably 0.010% or more.
- the Zr content is 0.100% or less, preferably 0.050% or less, and more preferably 0.030% or less.
- Hf (Hf: 0 to 0.100%) Hf (hafnium) is an element that contributes to the control of inclusions, particularly the fine dispersion of inclusions, and has the effect of increasing the toughness, so it may be contained as necessary. Therefore, the Hf content is 0% or more, preferably 0.001% or more, more preferably 0.005% or more, and still more preferably 0.010% or more. On the other hand, if the Hf content is excessive, deterioration of the surface properties may become apparent, so the Hf content is 0.100% or less, preferably 0.050% or less, and more preferably 0.030% or less.
- REM 0-0.100%
- REM rare earth element
- the REM content is 0% or more, preferably 0.001% or more, more preferably 0.005% or more, and still more preferably 0.010% or more.
- the REM content is 0.100% or less, preferably 0.050% or less, and more preferably 0.030% or less.
- REM is an abbreviation for Rare Earth Metal, and refers to an element belonging to the lanthanide series. REM is usually added as a misch metal.
- the steel sheet contains, among the above optional elements, B: 0.0001 to 0.0100%, Ti: 0.001 to 0.100%, Nb: 0.001 to 0.100%, Cr: 0.000%. 01 to 1.00%, Mo: 0.01 to 0.50%, and W: 0.01 to 0.50%, or two or more thereof.
- the steel plate contains V: 0.01-0.10%, Ni: 0.01-0.10%, Cu: 0.01-0.10%, Ca: 0.001- 0.100%, Mg: 0.001-0.100%, Zr: 0.001-0.100%, Hf: 0.001-0.100%, and REM: 0.001-0.100% You may contain the 1 type(s) or 2 or more types.
- the balance other than the above composition consists of Fe and impurities.
- impurities refers to components that are mixed in due to various factors in the manufacturing process, including raw materials such as ores and scraps, when steel sheets are industrially manufactured. It means what is allowed to be contained within a range that does not adversely affect the properties of the steel sheet.
- the analysis of the chemical composition in the steel sheet may be performed by any chemical analysis known to those skilled in the art, for example, by inductively coupled plasma mass spectrometry (ICP-MS method).
- ICP-MS method inductively coupled plasma mass spectrometry
- C and S may be measured using the combustion-infrared absorption method
- N may be measured using the inert gas fusion-thermal conductivity method.
- the present invention is directed to a galvanized steel sheet using a steel sheet having a thickness of 0.10 to 0.95 mm. More specifically, the object is a galvanized steel sheet using a steel sheet having a thickness of 0.10 to 0.95 mm, which can be suitably used for members such as automobile doors, bonnets or roofs.
- the plate thickness of the steel plate is preferably 0.20 mm or more, more preferably 0.30 mm or more, from the viewpoint of ensuring strength. From the viewpoint of weight reduction, the plate thickness is preferably thin, preferably 0.70 mm or less, more preferably 0.60 mm or less, and even more preferably 0.50 mm or less.
- the width of the zinc-based plated steel sheet (that is, steel sheet) is It is typically 1000 mm or more, optionally 1500 mm or more.
- the plate thickness of the steel plate may be determined using a micrometer or the like. When measuring the plate thickness of the plated steel plate from which the plated layer has been removed, the plated layer may be removed and the thickness may be measured with a micrometer or the like, or may be obtained by cross-sectional observation.
- the width of the steel sheet can be measured directly with a tape measure or tape measure.
- the zinc-based plated steel sheet according to the present invention has an internal oxide layer containing an oxide on the surface layer of the steel sheet (inside the steel sheet).
- the oxide of the internal oxide layer contains one or more of the elements contained in the steel sheet described above, typically Si, O, Fe, and Mn, and further In some cases, it has a component composition containing Al.
- oxides typically have compositions such as Mn 2 SiO 4 , SiO 2 and MnO.
- the outer oxide layer that is, the oxide layer is not formed in the form of a film on the surface of the steel sheet, but the inner oxide layer, that is, the oxide exists inside the steel sheet.
- the thickness per side of the internal oxide layer may be about 0.01 to 0.20 times the thickness of the steel sheet.
- the thickness of the internal oxide layer per side of the steel sheet in the present invention: A ( ⁇ m) is not particularly limited, but may be, for example, 1.0 ⁇ m or more, 2.0 ⁇ m or more, 3.0 ⁇ m or more, or 5.0 ⁇ m or more. good.
- the upper limit of A is not particularly limited, it may be, for example, 50.0 ⁇ m or less, 40.0 ⁇ m or less, 30.0 ⁇ m or less, or 20.0 ⁇ m or less from the viewpoint of suppressing excessive formation of decarburized layers.
- the zinc-based plated steel sheet according to the present invention has a decarburized layer near the surface of the steel sheet.
- the decarburized layer has a carbon concentration lower than that of the main portion (for example, the thickness center portion) of the steel sheet.
- the term "decarburized layer” refers to a region existing on the steel sheet side from the interface between the steel sheet and the zinc-based coating layer and having a lower carbon concentration than in the base material.
- the thickness of the decarburized layer is controlled with respect to the thickness of the steel sheet and the thickness of the internal oxide layer. strength reduction can be suppressed, and high strength can be achieved while ensuring platability.
- the thickness of the decarburized layer in the present invention is preferably as small as possible from the viewpoint of ensuring higher strength.
- B is not particularly limited, but is substantially 10 ⁇ m or more, for example, 15 ⁇ m or more, 20 ⁇ m or more, 25 ⁇ m or more, 30 ⁇ m or more, or 40 ⁇ m or more. good too.
- the upper limit of B is preferably 200 ⁇ m or less, more preferably 150 ⁇ m or less or 120 ⁇ m or less, and even more preferably 100 ⁇ m or less or 90 ⁇ m or less, from the viewpoint of ensuring higher and more uniform strength.
- A/B is less than 0.01, the formation of an internal oxide layer may be insufficient, resulting in poor plating properties, and/or a thick decarburized layer, resulting in insufficient strength.
- the lower limit of A/B is preferably 0.03 or 0.05, more preferably 0.10 or 0.15, still more preferably 0.20.
- the upper limit of A/B is substantially 0.50.
- the upper limit of A/B may be less than 0.50, 0.45, 0.40 or 0.30.
- the decarburized layer is preferably thin from the viewpoint of ensuring strength, but some is formed when the internal oxide layer is formed to ensure plating properties. Sa B does not become 0.
- A means the thickness of the internal oxide layer per side of the steel sheet.
- the thickness of the decarburized layer per side B ( ⁇ m) is preferred.
- the thickness of the steel sheet of the present invention is as thin as 0.10 to 0.95 mm (100 to 950 ⁇ m), such control is extremely important. Therefore, in the present invention, the upper limit of B/t is set to 0.200. When B/t is 0.200 or less, it is possible to suppress the influence of reduction in strength due to the presence of the decarburized layer, and to obtain a galvanized steel sheet having sufficient strength.
- B/t exceeds 0.200, the decarburized layer may become thicker than the thickness of the steel sheet, resulting in insufficient strength.
- the upper limit of B/t may be 0.190, 0.180, 0.160, 0.140, 0.120 or 0.100.
- the lower limit of B/t is substantially 0.001.
- the lower limit of B/t may be 0.010, 0.020, 0.030, 0.040 or 0.050.
- B means the thickness of the decarburized layer per side of the steel sheet. That is, when B affects the steel plate strength, both sides of the steel plate are affected.
- the galvanized steel sheets When galvanized steel sheets are used for automobile parts such as doors, bonnets or roofs, the galvanized steel sheets typically have a width of 1500 mm or more because these parts have a very large area. .
- the ratio of the thickness of the internal oxide layer on the surface of the steel sheet to the thickness of the decarburized layer and the ratio of the thickness of the decarburized layer to the thickness of the steel sheet are set within a predetermined range. In addition to controlling the thickness of the internal oxide layer and the decarburized layer in the width direction of the steel sheet, by strictly controlling the thickness variation Also, good properties can be reliably achieved in the entire steel sheet.
- the thickness of the internal oxide layer per side of the steel sheet A ( ⁇ m )
- the standard deviation of the thickness of the decarburized layer in the width direction: b ( ⁇ m) by controlling A: 1.0 ⁇ m or more, B: 10 ⁇ m or more, a/A: 0.15 or less, and b/B: 0.20 or less, the strength of the entire steel sheet is increased. and high plating properties can be reliably achieved.
- the width of the steel plate may be 1500 to 3000 mm, and may be, for example, 1600 mm or more, 1800 mm or more, or 2000 mm or more. As mentioned above, the width of the steel sheet can be measured directly with a tape measure or tape measure.
- the thickness of the internal oxide layer per side of the steel sheet A ( ⁇ m) and the standard deviation of the thickness of the internal oxide layer in the width direction: a ( ⁇ m), where A is 1 0 ⁇ m or more, and a/A is 0.15 or less.
- A/A 0.15 or less, it is possible to suppress variations in the thickness of the internal oxide layer in the width direction of the steel sheet having a width of 1500 to 3000 mm, and the thickness of the internal oxide layer in the entire steel sheet.
- a/A is preferably 0.14 or less or 0.12 or less, more preferably 0.10 or less, and still more preferably 0.08 or less.
- the lower limit of a/A is not particularly limited, but a/A may be greater than 0 or 0.01 or more because the thickness of the internal oxide layer varies somewhat during manufacturing.
- B 10 ⁇ m or more and b/B: 0.20 or less
- B 10 ⁇ m or more
- b/B 0.20 or less
- B 10 ⁇ m or more
- b/B 0.20 or less
- b/B 0.20 or less
- variation in the thickness of the decarburized layer in the width direction of the steel sheet having a width of 1500 to 3000 mm can be suppressed.
- the uniformity of the decarburized layer in the width direction greatly affects the appearance of the skin panel when it is slightly distorted.
- b/B is preferably 0.15 or less, more preferably 0.12 or less, and still more preferably 0.10 or less.
- the lower limit of b/B is not particularly limited, but b/B may be greater than 0 or 0.01 or more because the thickness of the decarburized layer varies somewhat during production.
- the thickness of the internal oxide layer A ( ⁇ m) is measured and the thickness variation: a ( ⁇ m) is calculated as follows. After chemically dissolving and removing the zinc-based coating layer of the zinc-based coated steel sheet to be measured with a solution such as hydrochloric acid containing an inhibitor, the composition in the thickness direction of the steel sheet is analyzed using a glow discharge optical emission surface spectrometer (GDS). and evaluate the thickness of the internal oxide layer.
- GDS glow discharge optical emission surface spectrometer
- the sputtering depth is measured by means of a roughness meter, a laser microscope, or the like after sputtering for a certain period of time from the surface of the steel sheet in the thickness direction of the steel sheet, and the sputtering rate per hour is calculated.
- Mn is internally oxidized
- the Mn concentration profile once decreases below the Mn signal intensity of the steel base, and then gradually increases to reach the Mn signal intensity of the steel base.
- the position where the Mn signal intensity reaches 0.9 times the Mn signal intensity of the steel base is defined as the internal oxidation position, and the sputtering time reaching this internal oxidation position is converted from the sputtering speed to the thickness.
- the internal oxide layer refers to a region where the Mn concentration is 0.9 times or less the Mn concentration of the steel base as measured by a glow discharge luminescence surface spectrometer (GDS).
- GDS glow discharge luminescence surface spectrometer
- FIG. 1 shows an example of a GDS profile such as Mn.
- the thickness A ( ⁇ m) per side of the internal oxide layer in the present invention is obtained.
- the standard deviation of the thickness of the internal oxide layer in the width direction: a ( ⁇ m) is the standard deviation of the thickness of the internal oxide layer at 18 locations obtained as described above.
- a high-frequency type GDS is used.
- the "one end" and the “other end” as the measurement positions are the positions 100 mm inside from the actual one end and the other end of the steel plate, respectively.
- the thickness of the decarburized layer B ( ⁇ m) is measured and the thickness variation: b ( ⁇ m) is calculated as follows.
- the thickness of the decarburized layer is evaluated by measuring the cross-sectional hardness distribution of the steel sheet. . Specifically, the steel sheet is corroded with 2% nital to observe the steel sheet structure and determine the thickness of the decarburized layer.
- the Vickers hardness of the cross section is measured every 5 ⁇ m from the surface (interface between the steel sheet and the coating layer) toward the plate thickness direction. It is often possible to determine if the measurement length is about 100 to 150 ⁇ m.
- the thickness of the decarburized layer is defined as the position where the hardness distribution reaches the steel plate hardness. That is, in the present invention, the "thickness of the decarburized layer” means the distance until the hardness distribution from the steel sheet surface by Vickers hardness reaches the steel sheet hardness.
- the “steel plate hardness” in the present embodiment is the average value of the hardness measured at arbitrary 10 points in the central portion in the thickness direction of the steel plate cross section.
- FIG. 2 An example of actual measurement of the thickness of the decarburized layer is shown in FIG. Although the Vickers hardness load is not particularly specified, it is desirable that the load is not too large since the measurement is performed every 5 ⁇ m.
- FIG. 2 was measured with a load of 25 gf. By performing the above operation at three or more locations and averaging the thicknesses of the decarburized layer obtained at each location, the thickness B ( ⁇ m) per side of the decarburized layer in the present invention is obtained.
- the widthwise standard deviation b ( ⁇ m) of the thickness of the decarburized layer in the present invention is the standard deviation of the thickness of the decarburized layer at 18 locations obtained as described above.
- the zinc-based plated steel sheet according to the present invention has a tensile strength of 550-1500 MPa.
- the tensile strength is preferably 580 MPa or higher or 600 MPa or higher, more preferably 620 MPa or higher, still more preferably 650 MPa or higher, and most preferably 700 MPa or higher.
- the tensile strength increases, the workability may decrease, so the tensile strength is set to 1500 MPa or less, and may be 1400 MPa or less or 1300 MPa or less.
- the tensile test is performed by the method specified in JIS-Z2241:2011 using a JIS No. 5 tensile test piece, and the crosshead test speed of the tensile test is 30 mm/min.
- the tensile test is performed at three points in the width direction of the steel plate: one end, the center, and the other end opposite to the one end. The test was performed at 3 locations at equal intervals between one end and the center, and 3 locations at equal intervals between the center and the other end, for a total of 9 locations. It is the tensile strength according to the invention.
- the zinc-based plating layer in the present invention is formed on at least one side of the steel sheet.
- Zinc-based plating layer typically refers to a plating layer whose main component (i.e., more than 50%) is composed of Zn. component is diffused, and as a result, Zn becomes 50% or less.
- the zinc-based plating layer can be formed by various methods, but hot-dip galvanization is preferred. Moreover, from the viewpoint of improving weldability and/or paintability, it is more preferable to perform an alloying treatment after hot-dip galvanizing.
- the zinc-based plated steel sheet according to the present invention is preferably a hot-dip galvanized steel sheet, and more preferably an alloyed hot-dip galvanized steel sheet.
- the zinc-based plating layer can be formed, for example, in a state in which the unplated portion is suppressed, and when alloying treatment can be formed in a state in which uneven alloying is suppressed.
- Component composition of zinc-based plating layer A preferable component composition contained in the zinc-based plating layer in the present invention will be described, but the component composition is not particularly limited as long as the zinc-based plating layer is a plating layer containing Zn. Typically, the zinc-based plating layer contains 50% by mass or more of Zn.
- % regarding the content of elements means “% by mass” unless otherwise specified.
- the numerical range represented using “to” means the range including the numerical values before and after "to” as the lower and upper limits.
- Fe (Fe: 0 to 15%) Fe can be contained in the coating layer by diffusing from the steel sheet when the coating layer containing Zn is formed on the steel sheet and then heat-treated. Therefore, the lower limit of Fe content may be 0%.
- the lower limit of the Fe content is 1%, preferably 3%. %, more preferably 5%.
- the upper limit of the Fe content is preferably 15%, preferably 12%, and more preferably 10%. Therefore, for example, when the zinc-based plating layer is an alloyed hot-dip galvanizing layer, the Fe content in the plating layer may be 5 to 15%.
- Al is an element that improves the corrosion resistance of the plating layer by being contained or alloyed with Zn, so it may be contained as necessary. Therefore, the Al content may be 0% when forming a plated layer by electrogalvanizing, for example.
- the Al content is preferably 0.01% or more, for example 0.1% or more, or 0.5% or more.
- the Al content is preferably 30% or less, for example, 20% or less, 10% or less, 5% or less, or 1% or less. .
- the plating bath does not contain Al
- an alloying treatment is performed to form an alloyed hot-dip galvanized layer
- Al in the steel diffuses into the coating layer.
- the Al content may be 0.01 to 1%.
- the basic component composition of the zinc-based plating layer is as described above.
- the zinc-based coating layer particularly the galvannealed layer, may optionally contain elements contained in the steel described above or other elements. Although these optional elements are not particularly limited, the total content is preferably 5% or less, more preferably 2% or less, from the viewpoint of sufficiently exhibiting the actions and functions of the basic components constituting the plating layer. more preferred.
- the balance other than the above component composition consists of Zn and impurities.
- the impurities in the zinc-based plating layer are components that are mixed due to various factors in the manufacturing process, including raw materials, when manufacturing the plating layer, and are intentionally added to the plating layer. does not mean anything.
- the plating layer may contain, as impurities, a trace amount of elements other than the above-described basic components and optional additive components within a range that does not interfere with the effects of the present invention.
- the coating weight of the zinc-based plating layer in the present invention is not particularly limited, but can be, for example, 10 to 100 g/m 2 .
- the amount of plating deposited per side greatly affects corrosion resistance.
- the lower limit of the adhesion amount is preferably 15 g/m 2 , more preferably 20 g/m 2 , still more preferably 30 g/m 2 .
- the upper limit of the adhesion amount per side is preferably 90 g/m 2 , more preferably 70 g/m 2 , and still more preferably 60 g/m 2 from the viewpoints of formability, weldability, and economy. good.
- the component composition and adhesion amount of the zinc-based plating layer can be determined by inductively coupled plasma (ICP) emission spectroscopic analysis. Specifically, the component composition and adhesion amount of the zinc-based coating layer can be obtained by dissolving only the coating layer from a zinc-based plated steel sheet having a zinc-based coating layer and performing ICP analysis on the resulting solution. .
- the amount of coating applied is the amount per side. Therefore, when a zinc-based plating layer is formed on both sides of a steel sheet, the amount of coating applied on both sides is calculated as the same.
- the steel sheet in the present invention includes a casting process in which molten steel having an adjusted chemical composition is cast to form a steel slab, a hot rolling process in which the steel slab is hot-rolled to obtain a hot-rolled steel sheet, and a surface oxide formed in the hot rolling process.
- a pickling step for removing (scale) and preferably an internal oxide layer, a cold rolling step for obtaining a cold rolled steel sheet by cold rolling, a grinding step for grinding the cold rolled steel plate, and an annealing step for annealing the cold rolled steel plate are performed.
- Conditions for the casting process are not particularly limited. For example, after smelting in a blast furnace or an electric furnace, various secondary smelting may be performed, and then casting may be performed by a method such as ordinary continuous casting, ingot casting, or thin slab casting. Although it is possible to use scrap as a raw material, the amount of scrap used is adjusted so that the content of each element in the obtained steel sheet satisfies the above ranges.
- a hot-rolled steel sheet can be obtained by hot-rolling the steel slab cast as described above.
- the hot-rolling process is performed by hot-rolling a cast steel slab directly or by reheating it after cooling it once.
- the heating temperature of the steel slab may be, for example, 1100.degree. C. to 1250.degree.
- Rough rolling and finish rolling are usually performed in the hot rolling process.
- the temperature and rolling reduction for each rolling may be appropriately determined according to the desired metallographic structure and plate thickness. In the present invention, since the thickness of the steel sheet is finally reduced to 0.10 to 0.95 mm, the load in the cold rolling process is large.
- the rolling reduction in hot rolling it is preferable to set the rolling reduction in hot rolling to a high value to reduce the sheet thickness during hot rolling as much as possible. Specifically, it is preferable to set the sheet thickness after hot rolling to 2.5 mm or less.
- the thickness of the internal oxidation layer and the decarburization layer formed near the surface of the steel sheet during hot rolling is almost constant, if the thickness after hot rolling is reduced, the effects of internal oxidation and decarburization during hot rolling are relatively small. becomes a big one.
- the coiling temperature it is preferable to set the coiling temperature to 600 ° C. or less, and 550 °C or less is more preferable.
- a lubricating oil with excellent lubricity as a hot rolling lubricating oil. It is preferable to uniformize the formation of an internal oxide layer in the hot rolling process by storing the wound hot-rolled coil with the hole of the inner diameter of the hot-rolled coil lying sideways (side of the hole).
- hot rolling lubricating oil If hot-rolling lubrication conditions are not appropriate, the strain distribution on the surface of the steel sheet during hot-rolling may become uneven. In such a case, the unevenness of internal oxidation in the sheet width direction during hot rolling becomes large, which is also disadvantageous for forming a uniform internal oxidation layer and decarburized layer in the subsequent annealing step. Therefore, as the hot-rolling lubricating oil for the hot-rolling rolls, it is preferable to use a hot-rolling lubricating oil having excellent lubricating properties, for example, it is preferable to use a Ca-sulfonate-containing lubricating oil. By using such a lubricating oil for hot rolling, the strain distribution on the surface of the steel sheet during hot rolling can be made uniform. Therefore, it is possible to remarkably reduce internal oxidation unevenness in the width direction during hot rolling.
- hot-rolled coils are stored in a state in which the inner diameter hole is vertical (vertical hole) or in a horizontal state (horizontal hole).
- the hot-rolled coil is stored vertically in a hole, the temperature variation in the sheet width direction becomes large, which may cause internal oxidation unevenness in the sheet width direction. In such a case, it is disadvantageous to form a uniform internal oxide layer and decarburized layer in the subsequent annealing process. Therefore, in order to suppress or reduce such internal oxidation unevenness, it is preferable to store the hot-rolled coil horizontally in the hole.
- a pickling process is performed to remove surface scales formed on the surface of the hot rolled steel sheet during the hot rolling process.
- a hydrochloric acid-based solution is usually used, and the same conditions can be applied to the present invention. Further, it is desirable to remove even an internal oxide layer formed during the hot rolling process by pickling.
- a cold-rolled steel sheet can be obtained by cold-rolling a hot-rolled steel sheet.
- the reduction ratio of cold rolling may be appropriately determined according to the desired metal structure and plate thickness, and may be, for example, 30 to 90%.
- the rolling reduction in the hot rolling process and the rolling reduction in the cold rolling process may be appropriately adjusted to obtain the final desired plate thickness, but the steel plate thickness in the present invention is as thin as less than 1 mm. Therefore, in order to prevent breakage in the cold rolling process, for example, it is preferable to set the rolling reduction in hot rolling larger than the rolling reduction in cold rolling.
- rinding process It removes foreign matter remaining on the surface of the steel sheet, removes the scale and internal oxide layer formed on the surface and surface layer of the steel sheet during hot rolling, homogenizes the surface texture, and removes the internal oxide layer in the subsequent annealing process. It is preferable to carry out a grinding step, for example, to facilitate formation. More specifically, the grinding process is carried out to sufficiently remove the internal oxide layer formed during hot rolling, and further, by imparting strain to the surface of the steel sheet, the surface of the steel sheet in the annealing atmosphere is reduced to the inside. Since the diffusion of oxygen is promoted and the reaction with oxygen is also activated, it is possible to promote the formation of an internal oxide layer in the annealing process.
- the grinding step is not particularly limited, but can be carried out, for example, by grinding the surface of the steel plate using a heavy grinding brush.
- a desired surface roughness and grinding amount can be achieved by appropriately selecting the number of heavy grinding brushes, the number of revolutions, the material, and the like.
- the grinding process is performed using a plurality of heavy grinding brushes to make the surface roughness uniform over the entire steel plate in the width direction, and to reduce the strain throughout the steel plate. It can be applied uniformly.
- the reaction with oxygen in the annealing atmosphere is activated at every position of the steel plate, and it is possible to uniformly control the variation in the thickness of the internal oxide layer and decarburized layer of the steel plate.
- the number of pairs of heavy grinding brushes arranged above and below the steel sheet is preferably three (three pairs) or more. This is because grinding little by little using a relatively large number of heavy grinding brushes is advantageous for making the surface roughness uniform across the entire steel sheet in the width direction and giving uniform strain.
- the total grinding amount of all heavy grinding brushes is preferably 2 g/m 2 or more per side.
- the grinding process can also be applied before the annealing and plating lines, which will be described later.
- the obtained cold-rolled steel sheet is annealed.
- Annealing is preferably performed at a temperature of 750° C. or higher, more preferably at a temperature of 780° C. or higher.
- the upper limit of the annealing temperature is preferably 920° C. or less from the viewpoint of suppressing the formation of an outer oxide layer.
- the heating rate to the annealing temperature is not particularly limited, and may be, for example, 1 to 10° C./sec. From the viewpoint of forming a sufficient internal oxide layer and suppressing the formation of an external oxide layer, the holding time at the annealing temperature should be about 5 to 300 seconds, preferably 50 to 100 seconds.
- the atmosphere in the annealing process is an important factor in controlling the internal oxide layer and decarburized layer. It is possible to set the initial stage of annealing to a high oxygen potential and then decrease the oxygen potential, or to increase the oxygen potential throughout the annealing.
- the oxygen potential can be represented by the common logarithm log (P H2O /P H2 ) of the value obtained by dividing the water vapor partial pressure PH2O in the annealing furnace by the hydrogen partial pressure PH2 , and the internal oxide layer and decarburized layer in the present invention can be expressed.
- the value obtained by the above formula can be controlled to -3.0 to -1.0.
- Methods for increasing the oxygen potential include using a combustion atmosphere, adding a small amount of oxygen, increasing the dew point, or combining these methods.
- the dew point is preferably -20°C or higher, preferably -10°C or higher. If the dew point is too low, an external oxide layer may form on the surface of the steel sheet.
- the annealing atmosphere is preferably a reducing atmosphere, more preferably a reducing atmosphere containing nitrogen and hydrogen, for example, a reducing atmosphere containing 5% hydrogen or less (eg, 5% hydrogen and 95% nitrogen).
- the annealing step can be performed continuously with the formation of the zinc-based plating layer, which will be described later.
- Formation of the internal oxide layer and the decarburized layer mainly depends on the conditions in the hot rolling process, the grinding process and the annealing process, as described above.
- the thickness of the internal oxide layer also depends on the amount of Si in the steel
- the thickness of the decarburized layer also depends on the amounts of Si, Mn and C in the steel. Increasing the Si content in the steel increases both the internal oxide layer thickness and the decarburized layer thickness, while increasing the Mn content in the steel decreases the decarburized layer thickness. Similarly, even if the amount of C in the steel is increased, the thickness of the decarburized layer becomes smaller.
- the grinding process is a very important process because applying strain to the steel sheet promotes the formation of an internal oxide layer in the subsequent annealing process.
- hot rolling lubricating oil hot rolling It is also necessary to appropriately select the storage method of the coil and the conditions of the grinding process. Therefore, in order to obtain appropriate values of A, B, A/B, B/t, a/A and/or b/B, the formation of internal oxide and decarburization layers is simply controlled during the annealing process.
- the zinc-based plating layer can be formed by either electrogalvanizing or hot-dip galvanizing, preferably by hot-dip galvanizing.
- the conditions of the plating treatment may be appropriately set in consideration of the desired composition, thickness, adhesion amount, etc. of the plating layer. For example, cooling after annealing is stopped at 430 to 500 ° C. Then, the cold-rolled steel sheet may be immersed in a molten zinc plating bath for 1 to 5 seconds.
- the plating amount may be, for example, 10 to 100 g/m 2 .
- the alloying treatment conditions may be within a normal range, for example, the alloying treatment may be performed at a temperature of 450 to 600.degree.
- Example A Production of zinc-based plated steel sheet
- a zinc-plated steel sheet was produced by zinc-plating a steel sheet having a thickness of 0.10 to 0.95 mm (100 to 950 ⁇ m) and a width of 1000 mm.
- molten steel having an adjusted chemical composition is cast to form a steel slab.
- the heating temperature of the billet during reheating was set to 1200°C
- the finish rolling temperature was set to 950°C.
- the sheet thickness and coiling temperature after hot rolling were as shown in Table 1.
- pickling was performed using hydrochloric acid to remove surface scales of 0.2 ⁇ m or less. After pickling, cold rolling was performed at the cold rolling reduction shown in Table 1.
- the oxygen potential obtained by the formula: log (P H2O /P H2 ) was set to -3.0 to -1.0.
- the dew point was controlled so that No. 20 and no. No. 23 was annealed at a low oxygen potential by controlling the dew point.
- For hot-dip galvanizing cooling after annealing was stopped at 480° C., and the cold-rolled steel sheet was immersed in a hot-dip zinc plating bath for 3 seconds to adjust the coating weight to about 50 g/m 2 per side.
- the composition in the thickness direction of the steel sheet was analyzed using a high frequency type GDS to evaluate the thickness of the internal oxide layer. Specifically, the sputtering depth was measured with a laser microscope after sputtering was performed from the surface of the steel sheet in the thickness direction of the steel sheet for a certain period of time, and the sputtering rate per hour was calculated.
- the position where the Mn signal intensity of 0.9 times the Mn signal intensity of the steel substrate was reached was specified, and the thickness of the internal oxide layer was obtained by converting the sputtering time to reach this position into the depth from the sputtering speed. By performing the above operation at three locations and averaging the thicknesses obtained at each location, the thickness A ( ⁇ m) (per one side) of the internal oxide layer was obtained.
- the thickness of the decarburized layer was evaluated by chemically dissolving and removing the plating layer of each example with a hydrochloric acid solution containing an inhibitor, and then measuring the cross-sectional hardness distribution of the steel sheet. Specifically, the steel sheet structure is observed by corroding the steel sheet with 2% nital, and the thickness of the decarburized layer is measured. The Vickers hardness of was measured every 5 ⁇ m. The measurement length was up to 100 ⁇ m. The position where the hardness distribution reached the steel plate hardness was specified, and the position was regarded as the thickness of the decarburized layer.
- the thickness of the decarburized layer was determined from the data obtained by performing the above measurements at three locations, and the thickness B ( ⁇ m) (per one side) of the decarburized layer in the present invention was obtained. A load of 25 gf was applied when Vickers hardness was measured.
- the tensile test was performed by the method specified in JIS-Z2241:2011 using a JIS No. 5 tensile test piece.
- the crosshead test speed of the tensile test was 30 mm/min. Table 2 shows the results obtained.
- the plating property was evaluated by evaluating the appearance of the galvanized steel sheet of each example. Specifically, for the example of the alloyed hot-dip galvanized steel sheet ("alloyed" in Table 1), the appearance after the alloying treatment was visually observed. ⁇ , and those that are visible or uncoated are x. For the example of a hot-dip galvanized steel sheet ("Hot-dip zinc" in Table 1), visually observe the appearance after plating, ⁇ indicates that no is visually recognized, and x indicates that it is visually recognized. Table 2 shows the results obtained.
- steel sheets with a tensile strength of 550 to 1500 MPa and a plating property evaluation of ⁇ or ⁇ were evaluated as galvanized steel sheets with sufficient strength and plating property.
- example no. In No. 104 since the C content was excessive, the strength of the steel sheet became too high, cold rolling could not be performed, and an appropriate thickness could not be obtained.
- Example no. In No. 109 the tensile strength decreased due to the low C content.
- Example no. In No. 110 the excessive Si content caused deterioration of the surface properties, resulting in poor plating properties.
- Example no. 113 had lower tensile strength due to lower Mn content.
- Example no. In No. 119 since the Al content was excessive, deterioration of the surface properties was caused, and as a result, the plating property was lowered.
- Example no. 120 and 123 since the dew point during annealing was low, an internal oxide layer and a decarburized layer were not formed, and sufficient plating properties could not be obtained.
- Example no. In No. 127 since the annealing time was long, the decarburized layer was excessively formed with respect to the internal oxide layer, and the B/t was increased, resulting in a decrease in tensile strength.
- the chemical composition of the steel sheet, the ratio of the thickness of the internal oxide layer on the surface of the steel sheet to the thickness of the decarburized layer (A/B), and the thickness of the decarburized layer Sufficient strength and plateability could be achieved by appropriately controlling the ratio (B/t) to the thickness of the steel sheet.
- Example No. in which the sum of the Si content and the Mn content (Si+Mn) is controlled to 5.00% or less and the ratio of the Si content to the Mn content (Si/Mn) is controlled to 1.50 or less.
- Nos. 101-103, 105-108, 112, 114-118, 121, 122 and 124-126 extremely high plating properties could be achieved.
- Example B Manufacture of wide zinc-based plated steel sheets
- zinc-based steel sheets were produced by zinc-plating steel sheets having a thickness of 0.10 to 0.95 mm (100 to 950 ⁇ m) and a width of 1500 to 3000 mm.
- molten steel with an adjusted chemical composition is cast to form a steel slab, the steel slab is once cooled and then reheated, and a rolling reduction of 50% or more using a Ca sulfonate-containing lubricating oil as a hot rolling lubricating oil.
- the obtained hot-rolled steel sheet was coiled, and the obtained hot-rolled coil was stored according to the storage method shown in Table 3.
- the heating temperature of the billet during reheating was set to 1200°C, and the finish rolling temperature was set to 850°C.
- Table 3 shows whether or not a Ca sulfonate-containing lubricating oil was used, the sheet thickness after hot rolling, and the coiling temperature. Thereafter, the hot-rolled coil was pickled with hydrochloric acid to remove surface scales of 0.2 ⁇ m or less. After pickling, cold rolling was performed at the cold rolling reduction shown in Table 3. A sample was taken from each cold-rolled steel sheet by a method conforming to JIS G0417:1999, and the chemical composition of the steel sheet was analyzed.
- the thickness of the steel sheet was measured with a micrometer at five arbitrary portions of the cold-rolled steel sheet, and the measured thicknesses were averaged to calculate the thickness. Further, the plate width was measured using a tape measure. Tables 3 and 4 show the chemical composition, thickness and width of the steel sheet of each example.
- the number of heavy grinding brushes shown in Table 3 in the grinding zone provided in front of the continuous plating line (when a pair of heavy grinding brushes arranged above and below the steel sheet is taken as one No. of heavy grinding brushes) were used to grind the surface to a total of 2 g/m 2 or more per side, and then annealing and hot-dip galvanization were performed. Except for No. 21, further alloying treatment was performed.
- Table 3 “alloyed” indicates that the alloying treatment was performed after hot-dip galvanizing, and "hot-dip zinc” indicates that the alloying treatment was not performed after hot-dip galvanizing.
- the temperature, dew point and holding time in annealing were as shown in Table 3, and the rate of temperature increase to the annealing temperature was 10°C/sec.
- the annealing atmosphere is a reducing atmosphere of 3% hydrogen and 97% nitrogen, and the dew point is controlled so that the oxygen potential obtained by the formula: log (P H2O /P H2 ) is -3.0 to -1.0. did.
- For hot-dip galvanizing cooling after annealing was stopped at 480° C., and the cold-rolled steel sheet was immersed in a hot-dip zinc coating bath for 3 seconds to adjust the coating weight to about 50 g/m 2 per side.
- the composition in the thickness direction of the steel sheet was analyzed using a high frequency type GDS to evaluate the thickness of the internal oxide layer. Specifically, the sputtering depth was measured with a laser microscope after sputtering was performed from the surface of the steel sheet in the thickness direction of the steel sheet for a certain period of time, and the sputtering rate per hour was calculated.
- the position where the Mn signal intensity of 0.9 times the Mn signal intensity of the steel substrate was reached was specified, and the thickness of the internal oxide layer was obtained by converting the sputtering time to reach this position into the depth from the sputtering speed.
- the above operation is performed at 9 points in the width direction of the steel plate (center, 100 mm position from both edges, 3 points each by dividing the edge and center into 4), a total of 18 points on both sides, and the thickness obtained at each point is averaged.
- the thickness A ( ⁇ m) (per one side) of the internal oxide layer was obtained, and the standard deviation a ( ⁇ m) in the width direction of the thickness of the internal oxide layer was obtained by calculating the standard deviation.
- the thickness of the decarburized layer was evaluated by chemically dissolving and removing the plating layer of each example with a hydrochloric acid solution containing an inhibitor, and then measuring the cross-sectional hardness distribution of the steel sheet. Specifically, the steel sheet structure is observed by corroding the steel sheet with 2% nital, and the thickness of the decarburized layer is measured. The Vickers hardness of was measured every 5 ⁇ m. The measurement length was up to 100 ⁇ m. The position where the hardness distribution reached the steel plate hardness was specified, and the position was regarded as the thickness of the decarburized layer.
- the tensile test was performed by the method specified in JIS-Z2241:2011 using a JIS No. 5 tensile test piece.
- the crosshead test speed of the tensile test was 30 mm/min. Table 4 shows the results obtained.
- the tensile test was performed at nine points in the same manner as for the internal oxide layer, and the average value was defined as the tensile strength according to the present invention.
- the tensile strength is 550 to 1500 MPa
- the plating property evaluation (excluding the plating property evaluation after applying 5% strain) is ⁇ or ⁇ . It was evaluated as a galvanized steel sheet having strength and plating properties.
- Example No. In 201 the tensile strength decreased due to the low C content.
- Example no. In No. 207 since the Si content was high, deterioration of the surface properties was caused, and as a result, the plating property was lowered.
- Example no. 208 had lower tensile strength due to lower Mn content.
- Example no. In No. 211 the high Al content caused deterioration of the surface properties, resulting in poor plating properties.
- Example no. In No. 225 since the coiling temperature was high, the formation of a decarburized layer in the hot rolling process could not be sufficiently suppressed, resulting in an increase in B/t and a decrease in tensile strength.
- the chemical composition of the steel sheet, the ratio of the thickness of the internal oxide layer on the surface of the steel sheet to the thickness of the decarburized layer (A/B), and the thickness of the decarburized layer Sufficient strength and plateability could be achieved by appropriately controlling the ratio (B/t) to the thickness of the steel sheet.
- the thickness of the internal oxide layer on the surface of the steel sheet (A), the thickness of the decarburized layer (B), and their widthwise variation (a / A and b/B) are properly controlled.
- Example No. In Nos. 213, 214, 223 and 224 although sufficient strength and plating properties could be achieved, occurrence of appearance unevenness was observed after 5% strain was applied.
- example no. In 213 and 214 since the number of heavy grinding brushes was small, it is considered that the uniformity of the surface roughness and the uniform application of strain over the entire steel plate in the width direction were not sufficient. Or, b/B was not obtained, and appearance unevenness occurred after applying a strain of 5%.
- the zinc-based plated steel sheet according to the present invention has sufficient plateability and strength, it is possible to provide a high-strength zinc-based steel sheet with excellent appearance properties, and the zinc-based plated steel sheet can be used for automobiles, home appliances, and building materials. etc., particularly for automobiles. Therefore, the present invention can be said to be an invention of extremely high industrial value.
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Abstract
Description
(1)
質量%で、
C:0.05~0.30%、
Si:0.01~3.00%、
Mn:0.80~3.00%、
Al:0.010~2.000%、
P:0.100%以下、
S:0.100%以下、
N:0.0300%以下、
O:0.010%以下、
B:0~0.0100%、
Ti:0~0.100%、
Nb:0~0.100%、
V:0~0.10%、
Cr:0~1.00%、
Ni:0~0.10%、
Cu:0~0.10%、
Mo:0~0.50%、
W:0~0.50%、
Ca:0~0.100%、
Mg:0~0.100%、
Zr:0~0.100%、
Hf:0~0.100%、及び
REM:0~0.100%
を含有し、残部がFe及び不純物からなる成分組成を有し、板厚が0.10~0.95mmである鋼板と、前記鋼板の少なくとも片面に形成された亜鉛系めっき層とを含み、
引張強度が550~1500MPaであり、
前記鋼板の片面あたりの内部酸化層の厚さ:A(μm)、前記鋼板の片面あたりの脱炭層の厚さ:B(μm)、及び前記鋼板の板厚:t(μm)とした場合に、
A/B:0.01~0.50であり、
B/t:0.001~0.200である、亜鉛系めっき鋼板。
(2)
前記鋼板の板幅が1500~3000mmであり、前記内部酸化層の厚さにおける幅方向の標準偏差:a(μm)及び前記脱炭層の厚さにおける幅方向の標準偏差:b(μm)とした場合に、
A:1.0μm以上であり、
B:10μm以上であり、
a/A:0.15以下であり、
b/B:0.20以下である、(1)に記載の亜鉛系めっき鋼板。
(3)
質量%で、Si+Mn:5.00%以下であり、Si/Mn:1.50以下である、(1)又は(2)に記載の亜鉛系めっき鋼板。
(4)
前記鋼板が、質量%で、
B:0.0001~0.0100%、
Ti:0.001~0.100%、
Nb:0.001~0.100%、
Cr:0.01~1.00%、
Mo:0.01~0.50%、及び
W:0.01~0.50%
のうちの1種又は2種以上を含有する成分組成を有する、(1)~(3)のいずれか1つに記載の亜鉛系めっき鋼板。
(5)
前記鋼板が、質量%で、
V:0.01~0.10%、
Ni:0.01~0.10%、
Cu:0.01~0.10%、
Ca:0.001~0.100%、
Mg:0.001~0.100%、
Zr:0.001~0.100%、
Hf:0.001~0.100%、及び
REM:0.001~0.100%
のうちの1種又は2種以上を含有する成分組成を有する、(1)~(4)のいずれか1つに記載の亜鉛系めっき鋼板。
(6)
前記亜鉛系めっき鋼板が合金化溶融亜鉛めっき鋼板であり、前記亜鉛系めっき層の成分組成が、Fe:5~15%、及びAl:0.01~1%を含み、残部がZn及び不純物からなり、前記亜鉛系めっき層の片面あたりの付着量が10~100g/m2である、(1)~(5)のいずれか1つに記載の亜鉛系めっき鋼板。
以下、本発明に係る亜鉛系めっき鋼板(以下、単に「めっき鋼板」という場合がある)について詳しく説明する。
(成分組成)
本発明における鋼板に含まれる成分組成について説明する。元素の含有量に関する「%」は、特に断りがない限り、「質量%」を意味する。成分組成における数値範囲において、「~」を用いて表される数値範囲は、特に指定しない限り、「~」の前後に記載される数値を下限値及び上限値として含む範囲を意味する。
C(炭素)は、亜鉛系めっき鋼板の強度を確保する上で重要な元素である。C含有量が不足すると、十分な強度を確保することができないおそれがある。したがって、C含有量は0.05%以上、好ましくは0.07%以上、より好ましくは0.08%以上、さらに好ましくは0.10%以上である。一方、C含有量が過剰であると、強度が過剰に高くなり、溶接性が低下するおそれがある。したがって、C含有量は0.30%以下、好ましくは0.25%以下、より好ましくは0.20%以下である。
Si(ケイ素)は、鋼板の強度を向上させるのに有効な元素である。また、Siは焼鈍中に酸素と結合して内部酸化物を形成する元素の1つである。その一方で、Siはめっき性、合金化速度へ影響を及ぼす元素でもある。Si含有量が不足すると、内部酸化が十分生成できないおそれがある。したがって、Si含有量は0.01%以上、好ましくは0.03%以上又は0.05%以上、より好ましくは0.10%以上又は0.30%以上である。一方、Si含有量が過剰であると、表面性状の劣化を引き起こし外観不良に繋がるおそれがある。またSi系の酸化皮膜(外部酸化層)が鋼板表面に生成されるおそれがある。したがって、Si含有量は3.00%以下、好ましくは2.50%以下、より好ましくは2.00%以下である。
Mn(マンガン)は、硬質組織を得ることで鋼板の強度を向上させるのに有効な元素である。また、Mnは焼鈍中に酸素と結合して内部酸化物を形成する元素の1つでもある。Mn含有量が不足すると、十分な強度を確保することができないおそれがある。したがって、Mn含有量は0.80%以上、好ましくは1.00%以上、より好ましくは1.20%以上である。一方、Mnを過剰に添加すると、Mn偏析によって金属組織が不均一になり、加工性が低下するおそれがある。したがって、Mn含有量は3.00%以下、好ましくは2.80%以下、より好ましくは2.50%以下である。
本発明における鋼板の成分組成において、外部酸化層の形成をより抑制して内部酸化層の形成を促進する観点から、Si含有量とMn含有量の和(Si+Mn)を5.00%以下にすることが好ましく、4.80%以下にすることがより好ましく、4.50%以下にすることがさらに好ましい。Si+Mnの下限は特に限定されないが、例えばSi+Mnは0.81%以上、0.90%以上、1.00%以上又は1.20%以上であってもよい。また、亜鉛系めっき鋼板の外観性状をより良好にする観点から、Mn含有量に対するSi含有量の比(Si/Mn)を1.50以下にすることが好ましく、1.20以下にすることがより好ましい。Si及びMnは鋼の強度の向上に寄与する一方で、過剰に含有されると外観性状を悪化する場合があり、そして、この外観性状への影響は、Mnに比べてSiの方が顕著である。したがって、強度の観点及び内部酸化物を形成する観点から、Si及びMnを所定量以上含ませ、かつ、Si/Mnを低くすることで、外観性状をより良好に保つことができる。Si/Mnの下限は特に限定されないが、例えばSi/Mnは0.01以上、0.03以上又は0.10以上であってもよい。Siに代替しうる元素としてAlがあるが、Siの代替としてAlを添加した場合、上記の和及び比にAl含有量を考慮する必要はない。
Al(アルミニウム)は、脱酸元素として作用する元素である。Al含有量が0.010%未満であると、十分に脱酸の効果を得ることができない場合がある。したがって、Al含有量は0.010%以上、好ましくは0.100%以上、より好ましくは0.200%以上である。一方、Alを過剰に含有すると加工性の低下や表面性状の劣化を引き起こすおそれがある。したがって、Al含有量は2.000%以下、好ましくは1.500%以下、より好ましくは1.000%以下である。
P(リン)は、一般に鋼に含有される不純物である。P含有量が0.100%超では溶接性が低下するおそれがある。したがって、P含有量は0.100%以下、好ましくは0.080%以下、より好ましくは0.050%以下、さらに好ましくは0.020%以下である。P含有量の下限は特に限定されないが、製造コストの観点から、P含有量は0%超又は0.001%以上であってもよい。
S(硫黄)は、一般に鋼に含有される不純物である。S含有量が0.100%超では溶接性が低下し、さらに、MnSの析出量が増加して曲げ性等の加工性が低下するおそれがある。したがって、S含有量は0.100%以下、好ましくは0.080%以下、より好ましくは0.050%以下、さらに好ましくは0.020%以下である。S含有量の下限は特に限定されないが、脱硫コストの観点から、S含有量は0%超又は0.001%以上であってもよい。
N(窒素)は、一般に鋼に含有される不純物である。N含有量が0.0300%超では溶接性が低下するおそれがある。したがって、N含有量は0.0300%以下、好ましくは0.0200%以下、より好ましくは0.0100%以下、さらに好ましくは0.0050%以下である。N含有量の下限は特に限定されないが、製造コストの観点からN含有量は0%超又は0.0010%以上であってもよい。
O(酸素)は、一般に鋼に含有される不純物である。O含有量が0.010%超では延性の劣化を招くおそれがある。したがって、O含有量は0.010%以下、好ましくは0.008%以下、より好ましくは0.006%以下、さらに好ましくは0.005%以下である。O含有量の下限は特に限定されないが、製造コストの観点からO含有量は0%超又は0.001%以上であってもよい。
B(ホウ素)は、焼入れ性を高めて強度の向上に寄与し、また粒界に偏析して粒界を強化して靭性を向上させる元素であるため、必要に応じて含有していてもよい。したがって、B含有量は0%以上、好ましくは0.0001%以上、より好ましくは0.0010%以上、さらに好ましくは0.0020%以上である。一方、十分な靭性及び溶接性を確保する観点から、B含有量は0.0100%以下、好ましくは0.0090%以下、より好ましくは0.0080%以下である。
Ti(チタン)は、TiCとして鋼の冷却中に析出し、強度の向上に寄与する元素であるため、必要に応じて含有していてもよい。したがって、Ti含有量は0%以上、好ましくは0.001%以上、より好ましくは0.010%以上、さらに好ましくは0.020%以上である。一方、過剰に含有すると粗大なTiNが生成して靭性が損なわれるおそれがあるため、Ti含有量は0.100%以下、好ましくは0.090%以下、より好ましくは0.080%以下である。
Nb(ニオブ)は、NbCを鋼中で形成するとともに結晶粒を微細化する効果があり強度の向上に寄与する元素であるため、必要に応じて含有していてもよい。したがって、Nb含有量は0%以上、好ましくは0.001%以上、より好ましくは0.010%以上、さらに好ましくは0.020%以上である。一方、十分な靭性及び溶接性を確保する観点から、Nb含有量は、0.100%以下、好ましくは0.090%以下、より好ましくは0.080%以下である。
V(バナジウム)は、VCを形成して強度の向上に寄与する元素であるため、必要に応じて含有していてもよい。したがって、V含有量は0%以上、好ましくは0.01%以上、より好ましくは0.02%以上、さらに好ましくは0.03%以上である。一方、十分な靭性及び溶接性を確保する観点から、V含有量は、0.10%以下、好ましくは0.09%以下、より好ましくは0.08%以下である。
Cr(クロム)は、鋼の強度や耐食性の向上に寄与する元素であるため、必要に応じて含有していてもよい。したがって、Cr含有量は0%以上、好ましくは0.01%以上、より好ましくは0.05%以上、さらに好ましくは0.10%以上である。一方、過剰に含有するとCr炭化物が多量に形成し、逆に焼入れ性が損なわれるおそれがあるため、Cr含有量は1.00%以下、好ましくは0.90%以下、より好ましくは0.80%以下、さらに好ましくは0.60%以下である。
Ni(ニッケル)は、鋼の強度や耐食性の向上に寄与する元素であるため、必要に応じて含有していてもよい。したがって、Ni含有量は0%以上、好ましくは0.01%以上、より好ましくは0.02%以上である。一方、製造コスト等の観点から、Ni含有量は0.10%以下、好ましくは0.08%以下である。
Cu(銅)は、鋼の強度や耐食性の向上に寄与する元素であるため、必要に応じて含有していてもよい。したがって、Cu含有量は0%以上、好ましくは0.01%以上、より好ましくは0.02%以上である。一方、靭性低下や鋳造後のスラブの割れや溶接性の低下を抑制する観点から、Cu含有量は0.10%以下、好ましくは0.08%以下である。
Mo(モリブデン)は、鋼の強度や耐食性の向上に寄与する元素であるため、必要に応じて含有していてもよい。したがって、Mo含有量は0%以上、好ましくは0.01%以上、より好ましくは0.10%以上である。一方、十分な靭性及び溶接性を確保する観点から、Mo含有量は0.50%以下、好ましくは0.40%以下、より好ましくは0.30%以下である。
W(タングステン)は、鋼の強度を高めるのに有効であるため、必要に応じて含有していてもよい。したがって、W含有量は0%以上、好ましくは0.01%以上、より好ましくは0.05%以上、さらに好ましくは0.10%以上である。一方、靭性と溶接性の低下を抑制する観点から、W含有量は0.50%以下、好ましくは0.40%以下、より好ましくは0.30%以下である。
Ca(カルシウム)は、介在物制御、特に介在物の微細分散化に寄与し、靭性を高める作用を有する元素であるため、必要に応じて含有していてもよい。したがって、Ca含有量は0%以上、好ましくは0.001%以上、より好ましくは0.005%以上、さらに好ましくは0.010%以上、さらにより好ましくは0.020%以上である。一方、過剰に含有すると表面性状の劣化が顕在化する場合があるため、Ca含有量は0.100%以下、好ましくは0.080%以下、より好ましくは0.050%以下である。
Mg(マグネシウム)は、介在物制御、特に介在物の微細分散化に寄与し、靭性を高める作用を有する元素であるため、必要に応じて含有していてもよい。したがって、Mg含有量は0%以上、好ましくは0.001%以上、より好ましくは0.003%以上、さらに好ましくは0.010%以上である。一方、過剰に含有すると表面性状の劣化が顕在化する場合があるため、Mg含有量は0.100%以下、好ましくは0.090%以下、より好ましくは0.080%以下である。
Zr(ジルコニウム)は、介在物制御、特に介在物の微細分散化に寄与し、靭性を高める作用を有する元素であるため、必要に応じて含有していてもよい。したがって、Zr含有量は0%以上、好ましくは0.001%以上、より好ましくは0.005%以上、さらに好ましくは0.010%以上である。一方、過剰に含有すると表面性状の劣化が顕在化する場合があるため、Zr含有量は0.100%以下、好ましくは0.050%以下、より好ましくは0.030%以下である。
Hf(ハフニウム)は、介在物制御、特に介在物の微細分散化に寄与し、靭性を高める作用を有する元素であるため、必要に応じて含有していてもよい。したがって、Hf含有量は0%以上、好ましくは0.001%以上、より好ましくは0.005%以上、さらに好ましくは0.010%以上である。一方、過剰に含有すると表面性状の劣化が顕在化する場合があるため、Hf含有量は0.100%以下、好ましくは0.050%以下、より好ましくは0.030%以下である。
REM(希土類元素)は、介在物制御、特に介在物の微細分散化に寄与し、靭性を高める作用を有する元素であるため、必要に応じて含有していてもよい。したがって、REM含有量は0%以上、好ましくは0.001%以上、より好ましくは0.005%以上、さらに好ましくは0.010%以上である。一方、過剰に含有すると表面性状の劣化が顕在化する場合があるため、REM含有量は0.100%以下、好ましくは0.050%以下、より好ましくは0.030%以下である。なお、REMとは、Rare Earth Metalの略であり、ランタノイド系列に属する元素をいう。REMは通常ミッシュメタルとして添加される。
本発明は、0.10~0.95mmの板厚を有する鋼板を用いた亜鉛系めっき鋼板を対象とする。より具体的には、例えば、自動車のドア、ボンネット又はルーフなどの部材に好適に使用できる、0.10~0.95mmの板厚を有する鋼板を用いた亜鉛系めっき鋼板を対象とする。鋼板の板厚は、強度を確保する観点から、好ましくは0.20mm以上であり、より好ましくは0.30mm以上であるとよい。軽量化の意味合いからは板厚は薄い方が好ましく、好ましくは0.70mm以下、より好ましくは0.60mm以下、さらに好ましくは0.50mm以下とすることが望ましい。また、本発明に係る亜鉛系めっき鋼板は、特にドア、ボンネット又はルーフなどの自動車用部材に使用されるのに好適に使用されるため、当該亜鉛系めっき鋼板(すなわち鋼板)の板幅は、典型的に1000mm以上であり、場合により1500mm以上である。鋼板の板厚は、マイクロメーター等を用いて求めればよい。めっき鋼板からめっき層を除いた鋼板の板厚を測る際は、めっき層を除去してマイクロメーター等で測定するか、又は断面観察から求めてもよい。鋼板の板幅はメジャーや巻き尺などで直接測定すればよい。
本発明に係る亜鉛系めっき鋼板は、鋼板の表層(鋼板の内部)に酸化物を含む内部酸化層を有する。当該内部酸化層の酸化物は、酸素に加え、上述した鋼板中に含まれる元素のうち1種又は2種以上を含むものであって、典型的に、Si、O、Fe、及びMn、さらに場合によりAlを含む成分組成を有する。典型的には酸化物はMn2SiO4やSiO2、MnO等の組成を有する。本発明に係る亜鉛系めっき鋼板においては、外部酸化層、すなわち鋼板の表面上に膜状に酸化物の層が形成されるのではなく、内部酸化層、すなわち鋼板の内部に酸化物が存在する層が形成されるため、めっき層を形成した場合に鋼成分(例えばFe)とめっき成分(例えばZn)との相互拡散が良好に起こり、鋼板上に亜鉛系めっきが良好に形成され、不めっき部等が形成されず外観性状に優れる亜鉛系めっき鋼板を得ることができる。また、合金化処理を行った場合に、合金化ムラを抑制でき、外観性状に優れる亜鉛系めっき鋼板を得ることができる。なお、めっき性確保のためには内部酸化層は一定量が形成されればよく、むしろ、内部酸化層を厚く形成すると強度低下の要因になる脱炭層も厚くなるため、内部酸化層を過剰に形成することは好ましくない。例えば、内部酸化層の片面あたりの厚さは、鋼板の板厚の0.01~0.20倍程度であってもよい。本発明における鋼板の片面あたりの内部酸化層の厚さ:A(μm)は、特に限定されないが、例えば1.0μm以上、2.0μm以上、3.0μm以上又は5.0μm以上であってもよい。Aの上限は特に限定されないが、脱炭層の過剰な形成を抑制する観点から、例えば、50.0μm以下、40.0μm以下、30.0μm以下又は20.0μm以下であってよい。
本発明に係る亜鉛系めっき鋼板は、鋼板の表面近傍に脱炭層を有する。脱炭層は、鋼板の主要部(例えば板厚中心部)の炭素濃度に比べて低い炭素濃度を有する。本発明において、脱炭層とは、鋼板と亜鉛系めっき層との界面から鋼板側に存在する領域であって、母材中に比べて炭素濃度が低くなっている領域のことをいう。また、本発明に係る亜鉛系めっき鋼板においては、後述するように、鋼板の板厚及び内部酸化層の厚さに対する脱炭層の厚さが制御されるため、脱炭層の存在による亜鉛系めっき鋼板の強度低下を抑制でき、めっき性を確保しながら高強度化を達成することができる。本発明における脱炭層の厚さ:B(μm)は、より高い強度を確保するという観点からは小さい方が好ましい。しかしながら、脱炭層は内部酸化層と共に幾らか形成されるため、特に限定されないが、Bは実質的に10μm以上であり、例えば、15μm以上、20μm以上、25μm以上、30μm以上又は40μm以上であってもよい。Bの上限は、より高く、特にはより高くかつより均一な強度を確保するという観点からは、200μm以下が好ましく、150μm以下又は120μm以下がより好ましく、100μm以下又は90μm以下がさらに好ましい。
本発明に係る亜鉛系めっき鋼板において、高いめっき性を得るために内部酸化層の形成を促進する必要がある一方で、高強度を得るためには脱炭層の形成を抑制する必要がある。したがって、内部酸化層の片面あたりの厚さA(μm)をある程度確保しつつ、脱炭層の片面あたりの厚さB(μm)の厚さを小さくすることが好ましい。よって、本発明において、A/Bの下限を0.01とする。A/Bが0.01以上であることで、高強度化及び高いめっき性の両方を達成することができる。A/Bが0.01未満となると、内部酸化層の形成が十分でなくめっき性が低下する、及び/又は、脱炭層が厚くなり強度が不十分となるおそれがある。A/Bの下限は、好ましくは0.03又は0.05、より好ましくは0.10又は0.15、さらに好ましくは0.20である。一方、通常、内部酸化が起こるような条件においては脱炭層の厚さBは内部酸化層の厚さAより厚くなるため、A/Bの上限は実質的に0.50となる。A/Bの上限は0.50未満、0.45、0.40又は0.30であってもよい。なお、脱炭層は、強度確保の観点からは薄いほうが好ましいが、めっき性の確保のために内部酸化層を形成した際に幾らかは形成されるため、本発明において脱炭層の片面あたりの厚さBは0にはならない。なお、Aは鋼板の片面あたりの内部酸化層の厚さを意味する。
さらに、本発明に係る亜鉛系めっき鋼板において、脱炭層の形成を抑制して高強度化を達成するために、鋼板の板厚t(μm)に対して脱炭層の片面あたりの厚さB(μm)を小さくすることが好ましい。特に、本発明の鋼板の板厚は0.10~0.95mm(100~950μm)と非常に薄いため、このような制御が極めて重要となる。よって、本発明において、B/tの上限を0.200とする。B/tが0.200以下であることで、脱炭層の存在による強度低下の影響を抑制でき、十分な強度を有する亜鉛系めっき鋼板を得ることができる。B/tが0.200を超えると、鋼板の板厚に対して脱炭層が厚くなり強度が不十分となるおそれがある。B/tの上限は、0.190、0.180、0.160、0.140、0.120又は0.100であってもよい。一方、本発明においては、めっき性確保のために内部酸化層をある程度の厚さで形成する必要があるため、脱炭層も幾らかは形成される。よって、B/tの下限は実質的に0.001となる。B/tの下限は、0.010、0.020、0.030、0.040又は0.050であってもよい。なお、Bは鋼板の片面あたりの脱炭層の厚さを意味する。すなわちBが鋼板強度に影響するときには鋼板の両側が影響を受けることになる。
ドア、ボンネット又はルーフなどの自動車用部材に亜鉛系めっき鋼板を用いる場合、これらの部材は非常に大きい面積を有するため、当該亜鉛系めっき鋼板は、典型的に1500mm以上の幅を有する場合がある。本発明に係る好ましい実施形態によれば、上で説明したように鋼板表面の内部酸化層の厚さと脱炭層の厚さとの比及び脱炭層の厚さと鋼板の板厚との比を所定の範囲内に制御することに加えて、鋼板の幅方向における内部酸化層及び脱炭層の厚さのばらつきを厳密に制御することで、このような板幅が大きい、したがって面積の大きい亜鉛系めっき鋼板においても、鋼板全体で良好な特性を確実に達成することができる。より具体的には、0.10~0.95mmの板厚を有しかつ1500~3000mmの大きな板幅を有する亜鉛系めっき鋼板において、鋼板の片面あたりの内部酸化層の厚さ:A(μm)、鋼板の片面あたりの脱炭層の厚さ:B(μm)、内部酸化層の厚さにおける幅方向の標準偏差:a(μm)、及び脱炭層の厚さにおける幅方向の標準偏差:b(μm)とした場合に、A:1.0μm以上、B:10μm以上、a/A:0.15以下、及びb/B:0.20以下に制御することで、鋼板全体で高強度化と高いめっき性の両方を確実に達成することができる。とりわけ、本発明に係る好ましい実施形態によれば、上記の構成により、鋼板の成形前だけでなく成形後すなわち歪を付与した後においても、高いめっき性を維持して外観を改善することができる。以下、本発明に係る好ましい実施形態についてより詳しく説明する。
鋼板の板幅は、1500~3000mmであればよく、例えば、1600mm以上、1800mm以上、又は2000mm以上であってもよい。先に述べたとおり、鋼板の板幅はメジャーや巻き尺などで直接測定すればよい。
本発明に係る好ましい実施形態では、鋼板の片面あたりの内部酸化層の厚さ:A(μm)及び内部酸化層の厚さにおける幅方向の標準偏差:a(μm)とした場合、Aは1.0μm以上であり、a/Aは0.15以下である。a/Aが0.15以下であることで、1500~3000mmの板幅を有する鋼板の幅方向の内部酸化層の厚さのばらつきを抑制することができ、鋼板全体で内部酸化層の厚さを十分に均一に制御でき、その結果、本発明に係る亜鉛系めっき鋼板が全体として高くかつ均一なめっき性を有することが可能となる。一方、a/Aの値が大きすぎると、鋼板全体の内部酸化層の厚さが十分に均一ではなく、幅方向でめっき性が均一とならず、亜鉛系めっき鋼板が全体として高くかつ均一なめっき性を有することができなくなるおそれがある。a/Aは、好ましくは0.14以下又は0.12以下であり、より好ましくは0.10以下、さらに好ましくは0.08以下である。a/Aの下限は特に限定されないが、製造上幾らか内部酸化層の厚さのばらつきは起こるため、a/Aは0超又は0.01以上であってもよい。
本発明に係る好ましい実施形態では、鋼板の片面あたりの脱炭層の厚さ:B(μm)及び脱炭層の厚さにおける幅方向の標準偏差:b(μm)とした場合、Bは10μm以上であり、b/Bは0.20以下である。b/Bが0.20以下であることで、1500~3000mmの板幅を有する鋼板の幅方向の脱炭層の厚さのばらつきを抑制することができる。幅方向の脱炭層の均一性は、外板パネルが若干の歪を付与されたときの外観に大きく影響する。すなわち、鋼板の板厚が薄く、鋼板強度が高く、かつ脱炭層厚さが相対的に厚くなるような条件において局部的な強度ムラが生じた場合に外から付与された歪が脱炭層の厚い部位つまり強度の低い部位に集中して鋼板表面の局部的な凹凸を惹き起こす場合がある。このような場合、成形前には良好な外観を有していても歪を付与した後にL方向(圧延方向)の外観ムラを生じることがある。b/Bを小さくすることで、局部的な材質ムラを抑制し、成形後においても高いめっき性を維持して均一な外観を確保することができる。b/Bは、好ましくは0.15以下であり、より好ましくは0.12以下、さらに好ましくは0.10以下である。b/Bの下限は特に限定されないが、製造上幾らか脱炭層の厚さのばらつきは起こるため、b/Bは0超又は0.01以上であってもよい。
内部酸化層の厚さ:A(μm)の測定及びその厚さのばらつき:a(μm)の算出は以下のように行う。測定対象の亜鉛系めっき鋼板の亜鉛系めっき層をインヒビターを添加した塩酸等の溶液で化学的に溶解、除去した後、グロー放電発光表面分析装置(GDS)で鋼板の板厚方向の組成を分析し、内部酸化層の厚さを評価する。具体的には、鋼板表面から鋼板の板厚方向に向かって一定時間スパッタリングした後のスパッタ深さを粗度計、レーザー顕微鏡等の手法で計測し、時間当たりのスパッタ速度を算出する。ここで、Mnが内部酸化すると、Mnの濃度プロファイルは一旦鋼素地のMn信号強度よりも低下した後に徐々に増加し鋼素地のMn信号強度に到る。本発明においては、鋼素地のMn信号強度の0.9倍のMn信号強度に達した位置を内部酸化位置と定義し、この内部酸化位置に到達したスパッタ時間をスパッタ速度より厚さに換算したものを内部酸化層の厚さとする。すなわち、本発明において、内部酸化層とは、グロー放電発光表面分析装置(GDS)による測定でMn濃度が鋼素地のMn濃度の0.9倍以下となる領域をいうものである。図1にMn等のGDSプロファイルの一例を示す。以上の操作を3箇所以上で行い、各箇所で求めた内部酸化層の厚さを平均化することで、本発明における内部酸化層の片面あたりの厚さA(μm)を得る。とりわけ、板幅が1500~3000mmの鋼板の場合には、鋼板の幅方向において、一方の端部、中央部、及び一方の端部と反対側の他方の端部の3箇所、一方の端部と中央部の間において等間隔で3箇所、及び中央部と他方の端部の間において等間隔で3箇所の合計9箇所、表裏で計18箇所で行い、各箇所で求めた内部酸化層の厚さを平均化することで、本発明における内部酸化層の片面あたりの厚さA(μm)を得る。また、本発明における内部酸化層の厚さにおける幅方向の標準偏差:a(μm)は、上記のように求めた18箇所の内部酸化層の厚さの標準偏差とする。GDSは高周波タイプのものを使用することとする。本明細書において、測定位置としての「一方の端部」及び「他方の端部」は、それぞれ鋼板の実際の一端及び他端から100mm内側に入った箇所とする。
脱炭層の厚さ:B(μm)の測定及びその厚さのばらつき:b(μm)の算出は以下のように行う。測定対象の亜鉛系めっき鋼板の亜鉛系めっき層をインヒビターを添加した塩酸等の溶液中で化学的に溶解、除去した後、鋼板の断面硬度分布を測定することで脱炭層の厚さを評価する。具体的には、鋼板を2%ナイタールで腐食させることで鋼板組織を観察し、脱炭層厚の当たりをつける。その後表面(鋼板とめっき層の界面)から板厚方向に向かって、断面のビッカース硬度を5μmごとに測定する。測定長は100~150μm程度あれば判断可能であることが多い。硬度分布が鋼板硬度に到達した位置までを脱炭層の厚さと定義する。すなわち、本発明において、「脱炭層の厚さ」とは、ビッカース硬度による鋼板表面からの硬度分布が鋼板硬度に到達するまでの距離をいうものである。なお本実施形態における「鋼板硬度」とは、鋼板断面の厚さ方向中心部のうち任意の10箇所において測定した硬度の平均値である。脱炭層の厚さの実際の測定例を図2に示す。ビッカース硬度の荷重は特に定めないが、5μmおきに測定することから大きすぎない荷重であることが望ましい。図2は25gfの荷重にて測定したものである。以上の操作を3箇所以上で行い、各箇所で求めた脱炭層の厚さを平均化することで、本発明における脱炭層の片面あたりの厚さB(μm)を得る。とりわけ、板幅が1500~3000mmの鋼板の場合には、鋼板の幅方向において、一方の端部、中央部、及び一方の端部と反対側の他方の端部の3箇所、一方の端部と中央部の間において等間隔で3箇所、中央部と他方の端部の間において等間隔で3箇所の合計9箇所、表裏で計18箇所で行い、各箇所で求めた脱炭層の厚さを平均化することで、本発明における脱炭層の片面あたりの厚さB(μm)を得る。また、本発明における脱炭層の厚さにおける幅方向の標準偏差:b(μm)は、上記のように求めた18箇所の脱炭層の厚さの標準偏差とする。
本発明に係る亜鉛系めっき鋼板は、550~1500MPaの引張強度を有する。引張強度が550MPa以上であることで、強度を十分に確保でき、例えば自動車用部材に用いる場合に薄肉化による軽量化を達成することができる。引張強度は、好ましくは580MPa以上又は600MPa以上、より好ましくは620MPa以上、さらに好ましくは650MPa以上、最も好ましくは700MPa以上である。一方、引張強度が高くなると加工性が低下するおそれがあるため、引張強度は1500MPa以下とし、1400MPa以下又は1300MPa以下であってもよい。引張試験は、JIS5号引張試験片を用いたJIS-Z2241:2011に規定される方法で行い、引張試験のクロスヘッド試験速度は、30mm/分とする。とりわけ、板幅が1500~3000mmの鋼板の場合には、引張試験は、鋼板の幅方向において、一方の端部、中央部、及び一方の端部と反対側の他方の端部の3箇所、一方の端部と中央部の間において等間隔で3箇所、中央部と他方の端部の間において等間隔で3箇所の合計9箇所で行い、各箇所で求めた引張強度の平均値を本発明に係る引張強度とする。
本発明における亜鉛系めっき層は、鋼板上の少なくとも片面に形成される。「亜鉛系めっき層」とは、典型的に主成分(すなわち50%超)がZnで構成されるめっき層のことをいうが、めっき後に熱処理(例えば合金化処理)等を行うことで鋼中の成分が拡散し、結果的にZnが50%以下になったものも包含する。亜鉛系めっき層は、種々の方法で形成することができるが、溶融亜鉛めっきを行うことが好ましい。また、溶接性及び/又は塗装性を向上させる観点から、溶融亜鉛めっき後に合金化処理することがより好ましい。よって、本発明に係る亜鉛系めっき鋼板は、溶融亜鉛めっき鋼板であることが好ましく、合金化溶融亜鉛めっき鋼板であることがより好ましい。本発明においては、鋼板の表層に外部酸化層ではなく内部酸化層が形成されているため、亜鉛系めっき層を、例えば不めっき部を抑制した状態で形成することができ、合金化処理した場合は合金化ムラを抑制した状態で形成することができる。
本発明における亜鉛系めっき層に含まれる好ましい成分組成について説明するが、亜鉛系めっき層はZnを含むめっき層であれば、当該成分組成は特に限定されない。典型的に、亜鉛系めっき層は50質量%以上のZnを含む。以下、元素の含有量に関する「%」は、特に断りがない限り、「質量%」を意味する。成分組成における数値範囲において、「~」を用いて表される数値範囲は、特に指定しない限り、「~」の前後に記載される数値を下限値及び上限値として含む範囲を意味する。
Feは、鋼板上にZnを含むめっき層を形成した後にめっき鋼板を熱処理した場合に鋼板から拡散することでめっき層中に含まれ得る。したがって、Fe含有量の下限は0%であってもよい。合金化溶融亜鉛めっき層を形成するために合金化処理を行った場合は、鋼中のFeがめっき層中に拡散するため、この場合は、Fe含有量の下限値は1%、好ましくは3%、より好ましくは5%であってもよい。一方、Fe含有量の上限値は15%であるとよく、12%であると好ましく、10%であるとより好ましい。よって、例えば、亜鉛系めっき層が合金化溶融亜鉛めっき層である場合は、めっき層中のFe含有量は5~15%であってもよい。
Alは、Znと共に含まれる又は合金化することでめっき層の耐食性を向上させる元素であるため、必要に応じて含有していてもよい。したがって、例えば電気亜鉛めっきでめっき層を形成するような場合にはAl含有量は0%であってもよい。ZnとAlとを含むめっき層を形成するために、好ましくは、Al含有量は0.01%以上であるとよく、例えば、0.1%以上、又は0.5%以上であってよい。一方、30%超では耐食性を向上させる効果が飽和するため、Al含有量は、30%以下であるとよく、例えば、20%以下、10%以下、5%以下又は1%以下であってよい。めっき浴にAlを含まない場合でも、合金化溶融亜鉛めっき層を形成するために合金化処理を行った場合は、鋼中のAlがめっき層中に拡散する。よって、この場合は、例えばAl含有量は0.01~1%であってもよい。
本発明における亜鉛系めっき層の付着量は特に限定されないが、例えば10~100g/m2であることができる。片面あたりのめっき付着量は耐食性に大きく影響する。付着量の下限値は、耐食性の観点から、好ましくは15g/m2、より好ましくは20g/m2、さらに好ましくは30g/m2であるとよい。一方、片面あたりの付着量の上限値は、成形性、溶接性、及び経済性の観点から、好ましくは90g/m2、より好ましくは70g/m2、さらに好ましくは60g/m2であるとよい。
以下において、本発明に係る亜鉛系めっき鋼板の好ましい製造方法について説明する。以下の説明は、本発明に係る亜鉛系めっき鋼板を製造するための特徴的な方法の例示を意図するものであって、当該亜鉛系めっき鋼板を以下に説明するような製造方法によって製造されるものに限定することを意図するものではない。
本発明における鋼板は、成分組成を調整した溶鋼を鋳造して鋼片を形成する鋳造工程、鋼片を熱間圧延して熱延鋼板を得る熱延工程、熱延工程で形成した表面酸化物(スケール)及び好ましくは内部酸化層を除去する酸洗工程、冷間圧延して冷延鋼板を得る冷延工程、冷延鋼板を研削する研削工程、及び冷延鋼板を焼鈍する焼鈍工程を行うことで得ることができる。
鋳造工程の条件は特に限定されない。例えば、高炉や電炉等による溶製に引き続き、各種の二次製錬を行い、次いで、通常の連続鋳造、インゴット法による鋳造、又は薄スラブ鋳造などの方法で鋳造すればよい。原料にはスクラップを使用することも可能であるが、スクラップの使用量は、得られる鋼板の各元素の含有量が上記の範囲を満たすように調整する。
上記のように鋳造した鋼片を熱間圧延して熱延鋼板を得ることができる。熱延工程は、鋳造した鋼片を直接又は一旦冷却した後に再加熱して熱間圧延することにより行われる。再加熱を行う場合には、鋼片の加熱温度は、例えば1100℃~1250℃であればよい。熱延工程においては、通常、粗圧延と仕上圧延とが行われる。各圧延の温度や圧下率は、所望の金属組織や板厚に応じて適宜決定すればよく、例えば仕上圧延温度を800~1050℃、仕上圧延の圧下率を50~80%としてもよい。本発明においては、鋼板の板厚を最終的に0.10~0.95mmに薄くするため、冷延工程での負荷が大きい。このため、熱間圧延の圧下率を高めに設定して熱延時に板厚をできるだけ小さくすることが好ましく、具体的には熱延後の板厚を2.5mm以下にすることが好ましい。しかしながら、熱延において鋼板の表面近傍に生成する内部酸化層及び脱炭層の厚さはほぼ一定であるため、熱延後の板厚を薄くすると、熱延における内部酸化及び脱炭の影響は相対的に大きなものとなる。一方で、例えば、熱延工程において生成した内部酸化層及び脱炭層がその後の酸洗工程及び研削工程によっても十分に除去されずに比較的多く残存してしまうと、焼鈍工程での内部酸化層及び脱炭層が良好に生成しないか又は不均一に生成してしまうこととなり望ましくない。そこで、熱延工程での内部酸化層及び脱炭層の形成を抑制して熱延での内部酸化及び脱炭の影響を小さくするために、捲取温度を600℃以下にすることが好ましく、550℃以下とすることがより好ましい。とりわけ、板幅が1500~3000mmの幅広の鋼板を製造する際には、これに加えて、以下で詳しく説明するように、熱延潤滑油として潤滑性に優れるものを使用すること、並びに熱延及び捲取後の熱延コイルを当該熱延コイルの内径の穴が横になった状態(穴横)で保管することにより、熱延工程における内部酸化層の形成を均一化することが好ましい。
熱延潤滑条件が適切でないと、熱延時の鋼板表面の歪分布が不均一となる場合がある。このような場合には、熱延時の板幅方向における内部酸化ムラが大きくなり、その後の焼鈍工程での均一な内部酸化層及び脱炭層の形成にとっても不利である。そこで、熱延ロールのための熱延潤滑油としては、潤滑性に優れた熱延潤滑油を使用することが好ましく、例えばCaスルホネート含有潤滑油を使用することが好ましい。このような熱延潤滑油を使用することで、熱延時の鋼板表面の歪分布を均一化することができる。このため、熱延時の幅方向における内部酸化ムラを顕著に低減することが可能となる。
熱延及び捲取後の熱延コイルは、その後の酸洗工程及び冷延工程に供されるまで一時保管される。一般的には熱延コイルの内径の穴が縦になった状態(穴縦)又は熱延コイルの内径の穴が横になった状態(穴横)で保管されることになる。しかしながら、熱延コイルを穴縦保管とすると、板幅方向の温度ばらつきが大きくなり、板幅方向における内部酸化ムラを生じる場合がある。このような場合には、その後の焼鈍工程での均一な内部酸化層及び脱炭層の形成にとって不利となる。そこで、このような内部酸化ムラを抑制又は低減するためには、熱延コイルを穴横保管とすることが好ましい。
熱延工程で熱延鋼板の表面に形成した表面スケールを除去するために酸洗工程が行われる。酸洗工程では、通常は塩酸系の溶液が用いられ、本発明においても同様の条件が適用できる。また酸洗で、熱延工程の際に生成した内部酸化層まで除去することが望ましい。
熱延鋼板を冷間圧延して冷延鋼板を得ることができる。冷間圧延の圧下率は、所望の金属組織や板厚に応じて適宜決定すればよく、例えば30~90%であればよい。本発明においては、熱延工程の圧下率と冷延工程の圧下率とを適宜調整して最終的な所望の板厚を得ればよいが、本発明における鋼板の板厚は1mm未満と薄いため、冷延工程での破断を防止するために、例えば、熱間圧延の圧下率を冷間圧延の圧下率より大きくしておくとよい。
鋼板表面に残存する異物を除去し、さらには熱延時に鋼板の表面及び表層に形成されたスケール及び内部酸化層を除去するとともに、表面性状を均一化したり、次の焼鈍工程における内部酸化層の形成を促進させたりするために、研削工程を実施することが好ましい。より具体的には、研削工程を実施して熱延時に形成された内部酸化層を十分に除去しつつ、さらに鋼板の表面に歪を付与することで、焼鈍雰囲気中の鋼板表面から内部への酸素の拡散が促進され、また当該酸素との反応も活性化されるため、焼鈍工程における内部酸化層の形成を促進させることが可能となる。研削工程は、特に限定されないが、例えば重研削ブラシを用いて鋼板の表面を研削することにより実施することができる。重研削ブラシの本数、回転数及び材質等を適切に選択することで所望の表面粗度及び研削量を達成することができる。とりわけ板幅が1500~3000mmの幅広の鋼板を製造する場合には、複数の重研削ブラシによる研削工程を実施することで、幅方向の鋼板全体にわたって表面粗度を均一化し、歪も鋼板全体にわたって均一に付与することができる。このため、幅広の鋼板であっても、鋼板のあらゆる位置で焼鈍雰囲気中の酸素との反応が活性化し、鋼板の内部酸化層及び脱炭層の厚さのばらつきを均一に制御することが可能となる。とりわけ、板幅が1500~3000mmの鋼板を製造する場合には、鋼板の上下に配置される一対の重研削ブラシの本数は、3本(3対)以上であることが好ましい。なぜならば、比較的多くの重研削ブラシを使用して少しずつ研削することが、幅方向の鋼板全体にわたる表面粗度の均一化や歪の均一な付与にとって有利だからである。研削量は全ての重研削ブラシの合計で片面あたり2g/m2以上であることが好ましい。研削工程は後述する焼鈍、めっきラインの前段で付与することも可能である。
次いで、得られた冷延鋼板に焼鈍を行う。焼鈍は、750℃以上の温度で行うと好ましく、780℃以上の温度で行うのがより好ましい。焼鈍温度の上限は、外部酸化層の形成を抑制する観点から、920℃以下であるとよい。焼鈍温度までの昇温速度は、特に限定されなく、例えば1~10℃/秒で行えばよい。また、内部酸化層を十分に形成し、外部酸化層の形成を抑制する観点から、当該焼鈍温度での保持時間は5~300秒程度、好ましくは50~100秒とすればよい。焼鈍時間が長すぎると、脱炭層が内部酸化層に対して過剰に生成してB/t値が高くなり、十分な強度が得られない場合がある。焼鈍工程における雰囲気は内部酸化層と脱炭層を制御するうえで重要な因子となる。焼鈍の初期を高酸素ポテンシャルとして、その後、酸素ポテンシャルを小さくすることも可能であり、あるいは焼鈍全体で酸素ポテンシャルを高くすることも可能である。酸素ポテンシャルは、焼鈍炉内の水蒸気分圧PH2Oを水素分圧PH2で除した値の常用対数log(PH2O/PH2)で表すことができ、本発明における内部酸化層及び脱炭層を得るために、例えば、上記式で求められる値を-3.0~-1.0に制御することができる。酸素ポテンシャルを高くする手法としては、燃焼雰囲気を使用する、酸素を微量添加する、露点を上昇させる、あるいはこれらを複合させる方法を採ることができる。露点を制御する場合、露点は、-20℃以上であるとよく、好ましくは-10℃以上である。露点が低すぎると、鋼板の表面上に外部酸化層が形成されるおそれがある。露点の上限は特に設けないが、常温よりも高くするためには結露を抑制する工夫が必要となる。焼鈍時の雰囲気は、好ましくは還元雰囲気、より好ましくは窒素及び水素を含む還元雰囲気、例えば水素5%以下の還元雰囲気(例えば、水素5%及び窒素95%)で行うとよい。なお、焼鈍工程は、後述する亜鉛系めっき層の形成と連続して行うことができる。
内部酸化層及び脱炭層の生成は、上記のとおり、主として、熱延工程、研削工程及び焼鈍工程における各条件に依存する。しかしながら、これに加えて、内部酸化層厚は鋼中のSi量にも依存し、また、脱炭層厚は鋼中のSi量、Mn量、及びC量にも依存する。鋼中のSi量を増大すると内部酸化層厚、脱炭層厚がともに大きくなり、鋼中のMn量を増大すると脱炭層厚は小さくなる。同様に、鋼中のC量を増大させても脱炭層厚は小さくなる。このため、A/Bを大きくするにはC量、Mn量を増大させることが効果的である。また、上記のとおり、熱延後の板厚を2.5mm以下まで薄くする場合、熱延における内部酸化及び脱炭の影響は相対的に大きなものとなる。このため、熱延工程において鋼板を比較的低温下で捲取することで熱延時の内部酸化及び脱炭を抑制してそれらの影響を小さくすることが重要となる。それに加え焼鈍工程の前に、熱延時に形成された内部酸化層を酸洗工程及び研削工程によって十分に除去することが重要となる。また、研削工程は、熱延時に形成された内部酸化層等の除去だけでなく、鋼板への歪の付与も行うものである。鋼板へ歪を付与することによってその後の焼鈍工程における内部酸化層の形成が促進されるため、研削工程は非常に重要な工程である。加えて、とりわけ1500mm以上の幅広の鋼板を製造する場合には、幅方向における内部酸化層厚及び脱炭層厚のばらつきa/A及びb/Bを制御する観点から、熱延潤滑油、熱延コイルの保管方法、及び研削工程の各条件も適切に選択することが必要となる。したがって、A、B、A/B、B/t、a/A及び/又はb/Bの値を適切なものとするためには、単に焼鈍工程において内部酸化層及び脱炭層の形成を制御するだけでは十分ではなく、鋼中のSi量、Mn量、及びC量に加えて、熱延工程及び研削工程の各条件も適切に制御することが必要となる。これらの各条件の相互の影響は複雑であるために一概に述べることはできないが、各条件をある程度固定することによってA、B、A/B、B/t、a/A及びb/Bを適切に制御することが可能である。いずれにしても、鋼板組成、熱延条件、研削条件及び焼鈍条件を単に組み合わせただけでは、本発明に係る内部酸化層及び脱炭層の特徴を満足させることはできず、これらの特徴を所望の範囲に制御するように、鋼板組成、熱延条件、研削条件及び焼鈍条件を適切に組み合わせることが重要となる。
亜鉛系めっき層の形成は、電気亜鉛めっきでも溶融亜鉛めっきでも行うことができるが、好ましくは溶融亜鉛めっき処理で行う。溶融亜鉛めっき処理の場合、めっき処理の条件は、所望のめっき層の成分組成、厚さ及び付着量等を考慮して適宜設定すればよく、例えば、焼鈍後の冷却を430~500℃で停止し、冷延鋼板を溶融亜鉛のめっき浴に1~5秒間浸漬すればよい。めっき付着量は、例えば10~100g/m2であればよい。
本例では、板厚が0.10~0.95mm(100~950μm)でかつ板幅が1000mmの鋼板に亜鉛系めっきを施した亜鉛系めっき鋼板を製造した。まず、成分組成を調整した溶鋼を鋳造して鋼片を形成し、鋼片を一旦冷却した後に再加熱して50%以上の圧下率にて熱間圧延し、得られた熱延鋼板を捲取った。全ての例において、再加熱時の鋼片の加熱温度を1200℃、仕上圧延温度950℃とした。熱延後の板厚及び捲取温度は表1に記載のとおりであった。その後、塩酸を用いて酸洗を行い、表面スケールが0.2μm以下になるまで除去した。酸洗後、表1に記載の冷延圧下率で冷間圧延を行った。各冷延鋼板からJIS G0417:1999に準拠した方法でサンプルを採取し、鋼板の成分組成を分析した。また、冷延鋼板の任意の部分5箇所についてマイクロメーターで鋼板の板厚を測定し、それらを平均して板厚tを算出した。各例の鋼板の成分組成及び板厚を表1及び2に示す。
各例のめっき層をインヒビターを添加した塩酸溶液で化学的に溶解、除去した後、高周波タイプGDSを用いて鋼板の板厚方向の組成を分析し、内部酸化層の厚さを評価した。具体的には、鋼板表面から鋼板の板厚方向に向かって一定時間スパッタリングした後のスパッタ深さをレーザー顕微鏡で計測し、時間当たりのスパッタ速度を算出した。鋼素地のMn信号強度の0.9倍のMn信号強度に達した位置を特定し、この位置に到達したスパッタ時間をスパッタ速度より深さに換算したものを内部酸化層の厚さとした。以上の操作を3箇所で行い、各箇所で求めた厚さを平均化することで、内部酸化層の厚さA(μm)(片面あたり)を得た。
各例のめっき層をインヒビターを添加した塩酸溶液で化学的に溶解、除去した後、鋼板の断面硬度分布を測定することで脱炭層の厚さを評価した。具体的には、鋼板を2%ナイタールで腐食させることで鋼板組織を観察し、脱炭層厚の当たりをつけ、その後、鋼板表面(鋼板とめっき層の界面)から板厚方向に向かって、断面のビッカース硬度を5μmごとに測定した。測定長は100μmまでとした。硬度分布が鋼板硬度に到達した位置を特定し、その位置を脱炭層の厚さとみなした。3箇所で上記測定を行いその3つのデータより脱炭層の厚さを判定し、本発明における脱炭層の厚さB(μm)(片面あたり)を得た。ビッカース硬度の測定時の荷重は25gfとした。
引張試験は、JIS5号引張試験片を用いたJIS-Z2241:2011に規定される方法で行った。引張試験のクロスヘッド試験速度は、30mm/分とした。得られた結果を表2に示す。
めっき性の評価については、各例の亜鉛系めっき鋼板の外観を評価することで行った。具体的には、合金化溶融亜鉛めっき鋼板(表1の「合金化」)の例については、合金化処理後の外観を目視観察し、合金化ムラが全く視認されないものを◎、ほぼ視認されないものを○、視認されるものあるいは不めっきが視認されるものを×とし、溶融亜鉛めっき鋼板(表1の「溶融亜鉛」)の例については、めっき後の外観を目視観察し、不めっき部が視認されないものを◎、視認されるものを×とした。得られた結果を表2に示す。
本例では、板厚が0.10~0.95mm(100~950μm)でかつ板幅が1500~3000mmの鋼板に亜鉛系めっきを施した亜鉛系めっき鋼板を製造した。まず、成分組成を調整した溶鋼を鋳造して鋼片を形成し、鋼片を一旦冷却した後に再加熱して、熱延潤滑油としてCaスルホネート含有潤滑油を使用して50%以上の圧下率にて熱間圧延し、得られた熱延鋼板を捲取り、得られた熱延コイルを表3に示す保管方法により保管した。全ての例において、再加熱時の鋼片の加熱温度を1200℃、仕上圧延温度850℃とした。Caスルホネート含有潤滑油の使用の有無、熱延後の板厚及び捲取温度は表3に記載のとおりであった。その後、熱延コイルに対して塩酸を用いて酸洗を行い、表面スケールが0.2μm以下になるまで除去した。酸洗後、表3に記載の冷延圧下率で冷間圧延を行った。各冷延鋼板からJIS G0417:1999に準拠した方法でサンプルを採取し、鋼板の成分組成を分析した。また、冷延鋼板の任意の部分5箇所についてマイクロメーターで鋼板の板厚を測定し、それらを平均して板厚を算出した。更に板幅を巻き尺を用いて測定した。各例の鋼板の成分組成、板厚及び板幅を表3及び4に示す。
各例のめっき層をインヒビターを添加した塩酸溶液で化学的に溶解、除去した後、高周波タイプGDSを用いて鋼板の板厚方向の組成を分析し、内部酸化層の厚さを評価した。具体的には、鋼板表面から鋼板の板厚方向に向かって一定時間スパッタリングした後のスパッタ深さをレーザー顕微鏡で計測し、時間当たりのスパッタ速度を算出した。鋼素地のMn信号強度の0.9倍のMn信号強度に達した位置を特定し、この位置に到達したスパッタ時間をスパッタ速度より深さに換算したものを内部酸化層の厚さとした。以上の操作を鋼板の幅方向9点(センター、両エッジより100mm位置、エッジとセンターを4分割した3点ずつ)、両面で計18箇所で行い、各箇所で求めた厚さを平均化することで、内部酸化層の厚さA(μm)(片面あたり)を得、また標準偏差を計算することで内部酸化層の厚さにおける幅方向の標準偏差a(μm)を得た。
各例のめっき層をインヒビターを添加した塩酸溶液で化学的に溶解、除去した後、鋼板の断面硬度分布を測定することで脱炭層の厚さを評価した。具体的には、鋼板を2%ナイタールで腐食させることで鋼板組織を観察し、脱炭層厚の当たりをつけ、その後、鋼板表面(鋼板とめっき層の界面)から板厚方向に向かって、断面のビッカース硬度を5μmごとに測定した。測定長は100μmまでとした。硬度分布が鋼板硬度に到達した位置を特定し、その位置を脱炭層の厚さとみなした。内部酸化層と同様に9点、両面で計18箇所で測定を行い平均値と標準偏差を計算して本発明における脱炭層の厚さB(μm)(片面あたり)、脱炭層の厚さにおける幅方向の標準偏差b(μm)を得た。ビッカース硬度の測定時の荷重は25gfとした。
引張試験は、JIS5号引張試験片を用いたJIS-Z2241:2011に規定される方法で行った。引張試験のクロスヘッド試験速度は、30mm/分とした。得られた結果を表4に示す。また、引張試験は内部酸化層と同様に9点で測定を行い、平均値を本発明に係る引張強度とした。
めっき性の評価については、例Aの場合と同じ基準で行った。
めっき性の評価が◎または○であったものについて、更に引張試験片を採取したのと同じ位置で試料を採取し、引張により5%の歪を付与した後の外観を評価した。引張前は外観ムラが認められなくても引張後に外観ムラが発生する場合があり、全ての試料で外観ムラが発生しないものを○、外観ムラが発生したものを×とした。
Claims (6)
- 質量%で、
C:0.05~0.30%、
Si:0.01~3.00%、
Mn:0.80~3.00%、
Al:0.010~2.000%、
P:0.100%以下、
S:0.100%以下、
N:0.0300%以下、
O:0.010%以下、
B:0~0.0100%、
Ti:0~0.100%、
Nb:0~0.100%、
V:0~0.10%、
Cr:0~1.00%、
Ni:0~0.10%、
Cu:0~0.10%、
Mo:0~0.50%、
W:0~0.50%、
Ca:0~0.100%、
Mg:0~0.100%、
Zr:0~0.100%、
Hf:0~0.100%、及び
REM:0~0.100%
を含有し、残部がFe及び不純物からなる成分組成を有し、板厚が0.10~0.95mmである鋼板と、前記鋼板の少なくとも片面に形成された亜鉛系めっき層とを含み、
引張強度が550~1500MPaであり、
前記鋼板の片面あたりの内部酸化層の厚さ:A(μm)、前記鋼板の片面あたりの脱炭層の厚さ:B(μm)、及び前記鋼板の板厚:t(μm)とした場合に、
A/B:0.01~0.50であり、
B/t:0.001~0.200である、亜鉛系めっき鋼板。 - 前記鋼板の板幅が1500~3000mmであり、前記内部酸化層の厚さにおける幅方向の標準偏差:a(μm)及び前記脱炭層の厚さにおける幅方向の標準偏差:b(μm)とした場合に、
A:1.0μm以上であり、
B:10μm以上であり、
a/A:0.15以下であり、
b/B:0.20以下である、請求項1に記載の亜鉛系めっき鋼板。 - 質量%で、Si+Mn:5.00%以下であり、Si/Mn:1.50以下である、請求項1又は2に記載の亜鉛系めっき鋼板。
- 前記鋼板が、質量%で、
B:0.0001~0.0100%、
Ti:0.001~0.100%、
Nb:0.001~0.100%、
Cr:0.01~1.00%、
Mo:0.01~0.50%、及び
W:0.01~0.50%
のうちの1種又は2種以上を含有する成分組成を有する、請求項1~3のいずれか1項に記載の亜鉛系めっき鋼板。 - 前記鋼板が、質量%で、
V:0.01~0.10%、
Ni:0.01~0.10%、
Cu:0.01~0.10%、
Ca:0.001~0.100%、
Mg:0.001~0.100%、
Zr:0.001~0.100%、
Hf:0.001~0.100%、及び
REM:0.001~0.100%
のうちの1種又は2種以上を含有する成分組成を有する、請求項1~4のいずれか1項に記載の亜鉛系めっき鋼板。 - 前記亜鉛系めっき鋼板が合金化溶融亜鉛めっき鋼板であり、前記亜鉛系めっき層の成分組成が、Fe:5~15%、及びAl:0.01~1%を含み、残部がZn及び不純物からなり、前記亜鉛系めっき層の片面あたりの付着量が10~100g/m2である、請求項1~5のいずれか1項に記載の亜鉛系めっき鋼板。
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CN202180097924.6A CN117280068A (zh) | 2021-05-10 | 2021-05-10 | 锌系镀覆钢板 |
KR1020237037994A KR20230165834A (ko) | 2021-05-10 | 2021-05-10 | 아연계 도금 강판 |
US18/290,088 US20240247357A1 (en) | 2021-05-10 | 2021-05-10 | Galvanized steel sheet |
PCT/JP2021/017739 WO2022239071A1 (ja) | 2021-05-10 | 2021-05-10 | 亜鉛系めっき鋼板 |
EP21941805.0A EP4339319A4 (en) | 2021-05-10 | 2021-05-10 | GALVANIZED STEEL SHEET |
MX2023012983A MX2023012983A (es) | 2021-05-10 | 2021-05-10 | Lamina de acero galvanizada. |
JP2023520590A JPWO2022239071A1 (ja) | 2021-05-10 | 2021-05-10 |
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PCT/JP2021/017739 WO2022239071A1 (ja) | 2021-05-10 | 2021-05-10 | 亜鉛系めっき鋼板 |
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US (1) | US20240247357A1 (ja) |
EP (1) | EP4339319A4 (ja) |
JP (1) | JPWO2022239071A1 (ja) |
KR (1) | KR20230165834A (ja) |
CN (1) | CN117280068A (ja) |
MX (1) | MX2023012983A (ja) |
WO (1) | WO2022239071A1 (ja) |
Cited By (4)
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WO2024150817A1 (ja) * | 2023-01-13 | 2024-07-18 | 日本製鉄株式会社 | 鋼板及びめっき鋼板 |
WO2024150822A1 (ja) * | 2023-01-13 | 2024-07-18 | 日本製鉄株式会社 | 鋼板及びめっき鋼板 |
WO2024150820A1 (ja) * | 2023-01-13 | 2024-07-18 | 日本製鉄株式会社 | 溶接継手 |
WO2024150824A1 (ja) * | 2023-01-13 | 2024-07-18 | 日本製鉄株式会社 | 溶接継手 |
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- 2021-05-10 EP EP21941805.0A patent/EP4339319A4/en active Pending
- 2021-05-10 KR KR1020237037994A patent/KR20230165834A/ko unknown
- 2021-05-10 US US18/290,088 patent/US20240247357A1/en active Pending
- 2021-05-10 WO PCT/JP2021/017739 patent/WO2022239071A1/ja active Application Filing
- 2021-05-10 JP JP2023520590A patent/JPWO2022239071A1/ja active Pending
- 2021-05-10 MX MX2023012983A patent/MX2023012983A/es unknown
- 2021-05-10 CN CN202180097924.6A patent/CN117280068A/zh active Pending
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Also Published As
Publication number | Publication date |
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CN117280068A (zh) | 2023-12-22 |
JPWO2022239071A1 (ja) | 2022-11-17 |
KR20230165834A (ko) | 2023-12-05 |
EP4339319A1 (en) | 2024-03-20 |
MX2023012983A (es) | 2023-11-22 |
EP4339319A4 (en) | 2024-06-19 |
US20240247357A1 (en) | 2024-07-25 |
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