WO2017135240A1 - HOT ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME, AND COLD ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME - Google Patents
HOT ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME, AND COLD ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME Download PDFInfo
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- WO2017135240A1 WO2017135240A1 PCT/JP2017/003379 JP2017003379W WO2017135240A1 WO 2017135240 A1 WO2017135240 A1 WO 2017135240A1 JP 2017003379 W JP2017003379 W JP 2017003379W WO 2017135240 A1 WO2017135240 A1 WO 2017135240A1
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- WIPO (PCT)
- Prior art keywords
- mass
- less
- stainless steel
- steel sheet
- ferritic stainless
- Prior art date
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- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 86
- 238000004519 manufacturing process Methods 0.000 title claims description 29
- 229910001068 laves phase Inorganic materials 0.000 claims abstract description 28
- 238000001556 precipitation Methods 0.000 claims abstract description 18
- 239000000203 mixture Substances 0.000 claims abstract description 17
- 239000012535 impurity Substances 0.000 claims abstract description 13
- 239000002245 particle Substances 0.000 claims abstract description 10
- 229910000831 Steel Inorganic materials 0.000 claims description 71
- 239000010959 steel Substances 0.000 claims description 71
- 239000010960 cold rolled steel Substances 0.000 claims description 39
- 238000005098 hot rolling Methods 0.000 claims description 35
- 239000010935 stainless steel Substances 0.000 claims description 17
- 238000000137 annealing Methods 0.000 claims description 16
- 230000009467 reduction Effects 0.000 claims description 15
- 238000005096 rolling process Methods 0.000 claims description 14
- 238000005097 cold rolling Methods 0.000 claims description 11
- 229910052748 manganese Inorganic materials 0.000 claims description 11
- 229910052710 silicon Inorganic materials 0.000 claims description 11
- 229910052757 nitrogen Inorganic materials 0.000 claims description 10
- 229910052717 sulfur Inorganic materials 0.000 claims description 9
- 238000004804 winding Methods 0.000 claims description 9
- 229910052698 phosphorus Inorganic materials 0.000 claims description 8
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 8
- 229910052726 zirconium Inorganic materials 0.000 claims description 7
- 229910052719 titanium Inorganic materials 0.000 claims description 6
- 229910052720 vanadium Inorganic materials 0.000 claims description 6
- 229910052721 tungsten Inorganic materials 0.000 claims description 5
- 229910052782 aluminium Inorganic materials 0.000 claims description 4
- 229910052796 boron Inorganic materials 0.000 claims description 4
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims description 4
- 229910052758 niobium Inorganic materials 0.000 claims description 4
- 229910000859 α-Fe Inorganic materials 0.000 claims 2
- 238000000034 method Methods 0.000 description 14
- 238000005260 corrosion Methods 0.000 description 9
- 230000007797 corrosion Effects 0.000 description 9
- 229910052799 carbon Inorganic materials 0.000 description 7
- 230000003647 oxidation Effects 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 230000009471 action Effects 0.000 description 3
- 230000002411 adverse Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- YRKCREAYFQTBPV-UHFFFAOYSA-N acetylacetone Chemical compound CC(=O)CC(C)=O YRKCREAYFQTBPV-UHFFFAOYSA-N 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 238000010273 cold forging Methods 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- OKIZCWYLBDKLSU-UHFFFAOYSA-M N,N,N-Trimethylmethanaminium chloride Chemical compound [Cl-].C[N+](C)(C)C OKIZCWYLBDKLSU-UHFFFAOYSA-M 0.000 description 1
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B3/02—Rolling special iron alloys, e.g. stainless steel
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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
- C21D6/004—Heat treatment of ferrous alloys containing Cr and 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
- C21D6/005—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
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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
- C21D8/0263—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
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
- C21D8/0426—Hot rolling
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- 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
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
- C21D8/0436—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
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
- C21D8/0463—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing 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
- 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
- C21D9/48—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals deep-drawing sheets
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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
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of 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
- C22C38/18—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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- 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
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—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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- 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
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—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
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B15/00—Arrangements for performing additional metal-working operations specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B2015/0057—Coiling the rolled product
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B2261/00—Product parameters
- B21B2261/20—Temperature
- B21B2261/21—Temperature profile
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/004—Dispersions; Precipitations
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
Definitions
- the present invention relates to an Nb-containing ferritic stainless steel hot-rolled steel sheet and a manufacturing method thereof, and an Nb-containing ferritic stainless steel cold-rolled steel sheet and a manufacturing method thereof.
- the present invention relates to an Nb-containing ferritic stainless steel hot-rolled steel sheet and a method for manufacturing the same, and an Nb-containing ferritic stainless steel cold-rolled steel sheet and a method for manufacturing the same.
- the exhaust pipe part means a part through which exhaust gas can flow, and particularly means parts such as an exhaust manifold, a front pipe, a center pipe, and a catalytic converter outer cylinder in an automobile.
- the exhaust pipe flange part means a part that constitutes a flange part that is welded and joined to an end part of the exhaust pipe part and that bears a fastening function between the exhaust pipe part and another part.
- an austenitic stainless steel plate having good manufacturability has been generally used as the stainless steel plate, but replacement with a ferritic stainless steel plate advantageous in terms of thermal expansion coefficient and cost is progressing.
- a ferritic stainless steel plate include an Nb-containing ferritic stainless steel plate.
- the exhaust pipe flange part is manufactured by cold forging a hot-rolled steel sheet. Further, the exhaust pipe flange part generally has a hole corresponding to the end of the exhaust pipe part, a hole for fastening the bottle, and is also subjected to cutting. Therefore, workability is required for the hot-rolled steel sheet used for manufacturing the exhaust pipe flange part. Further, the exhaust pipe component is generally manufactured by pressing a cold-rolled steel sheet or performing various processes after pipe-working the cold-rolled steel sheet. For this reason, workability is also required for cold-rolled steel sheets used in the manufacture of exhaust pipe components. In particular, with the recent downsizing of exhaust pipe components (particularly, exhaust manifolds), further improvement in workability of cold-rolled steel sheets is desired.
- the workability of a cold-rolled steel sheet can be expressed by using a Rankford value (hereinafter referred to as “r value”) as an index.
- r value Rankford value
- the Nb-containing ferritic stainless steel sheet is liable to cause a decrease in toughness due to the formation of a Laves phase (intermetallic compound mainly composed of Fe 2 Nb) during hot rolling.
- ferritic stainless steel sheets are inherently susceptible to embrittlement at 475 ° C. For this reason, when a Nb-containing ferritic stainless steel hot-rolled steel sheet having a thickness gauge (5 mm to 10 mm) is manufactured and cold-rolled, cracks are likely to occur and it is difficult to increase the cold rolling reduction ratio.
- Patent Document 1 As a method for improving the toughness of the Nb-containing ferritic stainless steel hot-rolled steel sheet, for example, a method for suppressing the generation of Laves phase by controlling the total amount of C and N within a specific range is proposed in Patent Document 1. ing. Moreover, as a method for improving the workability of the Nb-containing ferritic stainless steel cold-rolled steel sheet, for example, a method for controlling the hot-rolling finishing start temperature, the end temperature, the hot-rolled sheet annealing temperature, and the like is proposed in Patent Document 2. .
- Patent Document 1 is directed to a Nb-containing ferritic stainless steel hot-rolled steel sheet having a thickness of about 4.5 mm, and a Laves phase is generated for a thick gauge Nb-containing ferritic stainless steel hot-rolled steel sheet. It cannot be suppressed sufficiently. Moreover, even if it uses the method of patent document 2, there exists a problem that workability of a Nb containing ferritic stainless steel cold-rolled steel plate is not fully ensured.
- the present invention has been made to solve the above problems, and an object of the present invention is to provide a Nb-containing ferritic stainless steel hot rolled steel sheet excellent in toughness and workability and a method for producing the same. Another object of the present invention is to provide an Nb-containing ferritic stainless steel cold-rolled steel sheet excellent in workability and a method for producing the same.
- the present inventor when hot-rolling a stainless steel slab having a specific composition, keeps it at a temperature of 1100 ° C. to 1000 ° C. for 60 seconds or more and finishes heat.
- the amount of Nb carbonitride and Laves phase can be controlled within an appropriate range by setting the rolling temperature to 850 ° C. or more and winding at a winding temperature of 550 ° C. or less after hot rolling.
- Nb-containing ferritic stainless steel The present inventors have found that the toughness of the hot-rolled steel sheet is improved and have completed the present invention.
- the present inventors can increase the r value to 1.2 or more by annealing the Nb-containing ferritic stainless steel hot-rolled steel sheet, followed by cold rolling at a rolling reduction of 70% or more and annealing. As a result, it has been found that the workability of the Nb-containing ferritic stainless steel cold-rolled steel sheet is improved, and the present invention has been completed.
- the present invention is C: 0.030 mass% or less, Si: 2.00 mass% or less, Mn: 2.00 mass% or less, P: 0.050 mass% or less, S: 0.040 mass% or less.
- Cr 10.00% by mass to 25.00% by mass
- N 0.030% by mass or less
- Nb 0.01% by mass to 0.80% by mass, with the balance being Fe and inevitable impurities
- C 0.030 mass% or less, Si: 2.00 mass% or less, Mn: 2.00 mass% or less, P: 0.050 mass% or less, S: 0.040 mass% or less Cr: 10.00% by mass to 25.00% by mass, N: 0.030% by mass or less, Nb: 0.01% by mass to 0.80% by mass, with the balance being Fe and inevitable impurities
- S 0.040 mass% or less
- Cr 10.00% by mass to 25.00% by mass
- N 0.030% by mass or less
- Nb 0.01% by mass to 0.80% by mass
- C 0.030 mass% or less, Si: 2.00 mass% or less, Mn: 2.00 mass% or less, P: 0.050 mass% or less, S: 0.040 mass% or less Cr: 10.00% by mass to 25.00% by mass, N: 0.030% by mass or less, Nb: 0.01% by mass to 0.80% by mass, with the balance being Fe and inevitable impurities
- An Nb-containing ferritic stainless steel cold-rolled steel sheet having a composition, wherein the precipitation amount of Nb carbonitride is 0.2% by mass or more, and there are 10 or less Laves phases having a particle size of 0.1 ⁇ m or less per 10 ⁇ m 2 area.
- the Nb-containing ferritic stainless steel cold-rolled steel sheet has an r value of 1.2 or more. Furthermore, the present invention provides a method for producing an Nb-containing ferritic stainless steel cold-rolled steel sheet, characterized by annealing the Nb-containing ferritic stainless steel hot-rolled steel sheet, followed by cold rolling at a rolling reduction of 70% or more. It is.
- the Nb containing ferritic stainless steel hot-rolled steel plate excellent in toughness and workability, and its manufacturing method can be provided.
- the Nb containing ferritic stainless steel cold-rolled steel plate excellent in workability and its manufacturing method can be provided.
- the Nb-containing ferritic stainless steel hot-rolled steel sheet of the present invention (hereinafter sometimes abbreviated as “hot-rolled steel sheet”) contains C, Si, Mn, P, S, Cr, N, and Nb, with the balance being Fe. And a composition comprising inevitable impurities.
- the hot-rolled steel sheet of the present invention may have a composition further containing one or more of Ni, Mo, Cu, Co, Al, W, V, Ti, Zr, B, rare earth elements, and Ca. .
- the hot-rolled steel sheet of the present invention will be described in detail.
- C 0.030% by mass or less> C is a factor that hardens the steel and lowers the toughness of the hot-rolled steel sheet. Therefore, the C content is limited to 0.030% by mass or less. However, it is not necessary to extremely reduce the C content, and generally 0.001% to 0.030% by weight, preferably 0.003% to 0.025% by weight, and more preferably 0.005% by weight. A C content of ⁇ 0.020 mass% may be used.
- Si and Mn are effective as a deoxidizer and have an effect of improving high-temperature oxidation resistance.
- Si and Mn are effective as a deoxidizer and have an effect of improving high-temperature oxidation resistance.
- Si and Mn are effective to secure a content of 0.05% by mass or more for Si and 0.05% by mass or more for Mn.
- both Si and Mn are limited to a content of 2.00% by mass or less.
- the minimum of content of Si and Mn is not specifically limited, Generally 0.05 mass%, Preferably it is 0.1 mass%, More preferably, it is 0.15 mass%.
- P and S may cause a decrease in corrosion resistance. Therefore, the P content is limited to 0.050 mass% or less, and the S content is limited to 0.040 mass% or less.
- the P content may be in the range of 0.010 mass% to 0.050 mass%, and the S content may be in the range of 0.0005 mass% to 0.040 mass%.
- the preferable content of P is 0.020 mass% to 0.040 mass%, and the preferable content of S is 0.001 mass% to 0.010 mass%. In particular, when emphasizing corrosion resistance, it is effective to limit the S content to 0.005% by mass or less.
- Cr is an important element for ensuring the corrosion resistance as stainless steel, and is also effective in improving high-temperature oxidation resistance.
- a Cr content of 10.00% by mass or more is required.
- the content of Cr is preferably 13.50% by mass or more, more preferably 17.00% by mass or more from the viewpoint of exerting the above-described action.
- the Cr content is limited to 25.00 mass% or less, preferably 22.00 mass% or less, more preferably 20.00 mass% or less.
- N 0.030% by mass or less> N becomes a factor which reduces toughness. Therefore, the N content is limited to 0.030% by mass or less. However, it is not necessary to extremely reduce the N content. Generally, the N content may be 0.001% by mass to 0.030% by mass, and preferably 0.005% by mass to 0.025% by mass.
- Nb 0.01% by mass to 0.80% by mass>
- Nb is an extremely effective element for fixing the C and N to suppress grain boundary segregation of Cr carbonitrides (carbides / nitrides) and to maintain high corrosion resistance and high temperature oxidation resistance of the steel. Therefore, the Nb content needs to be 0.01% by mass or more.
- the Nb content is effectively 0.05% by mass or more, and more preferably 0.20% by mass or more.
- the content of Nb is too high, it is not preferable because it promotes toughness reduction of the hot-rolled steel sheet.
- the Nb content is limited to 0.80% by mass or less, preferably 0.60% by mass or less.
- Ni has an action of suppressing the progress of corrosion, and can be added as necessary. In that case, it is effective to secure a Ni content of 0.01% by mass or more. However, if a large amount of Ni is contained, workability may be adversely affected. Therefore, when Ni is added, it is necessary to carry out within a range of 2.00% by mass or less, preferably 1.00% by mass or less.
- Mo is an element effective for improving the corrosion resistance, and can be added as necessary. In that case, it is effective to secure a Mo content of 0.02 mass% or more, and it is more effective to set it to 0.50 mass% or more. However, if a large amount of Mo is contained, the toughness is adversely affected. Therefore, when Mo is added, it is necessary to be performed in a range of 2.50% by mass or less, preferably 1.50% by mass or less.
- Cu is an element effective not only for improving low-temperature toughness but also for improving high-temperature strength. Therefore, Cu can be added as needed. In that case, it is effective to secure a Cu content of 0.02 mass% or more. However, when a large amount of Cu is added, the workability is rather lowered. When adding Cu, it is necessary to carry out in 1.80 mass% or less, Preferably it is 0.80 mass% or less.
- Co is an element contributing to low temperature toughness, and can be added as necessary. In that case, it is effective to secure a Co content of 0.010% by mass or more. However, since excessive addition of Co causes a decrease in ductility, it is necessary to add Co in a range of 0.50% by mass or less.
- Al is an element effective as a deoxidizer, and can be added as necessary. In that case, it is effective to make Al content 0.005 mass% or more. However, if a large amount of Al is contained, it causes a decrease in toughness. Therefore, when Al is contained, the Al content is limited to 0.50% by mass or less, preferably 0.20% by mass or less.
- W and V are effective elements for improving the high-temperature strength, and one or more of them can be added as necessary. In that case, it is effective to secure a content of 0.10% by mass or more for W and 0.10% by mass or more for V. However, if these elements are added in a large amount, the steel becomes hard and causes cracking during cold rolling.
- W it is necessary to carry out in 1.80 mass% or less, Preferably it is 0.50 mass% or less.
- V it is necessary to carry out in the range of 0.30 mass% or less, preferably 0.15 mass% or less.
- Ti and Zr have an action of fixing C and N, and are effective elements for maintaining high corrosion resistance and high temperature oxidation resistance of steel. Therefore, one or more of Ti and Zr can be added as necessary. In that case, it is effective to secure a content of 0.01% by mass or more for Ti and 0.02% by mass or more for Zr. However, if excessive Ti is contained, the reduction in toughness of the hot-rolled coil is promoted. Therefore, when Ti is added, it is necessary to carry out within a range of 0.50 mass% or less. Further, when a large amount of Zr is contained, it becomes a factor that hinders workability. Therefore, when adding Zr, it is necessary to carry out within a range of 0.20 mass% or less.
- B is an element that improves corrosion resistance and workability by addition of a small amount, and one or more of these can be added as necessary. In that case, it is effective to secure a B content of 0.0001% by mass or more. However, if excessive B is contained, the hot workability is adversely affected. Therefore, when B is added, it is necessary to carry out within a range of 0.0050 mass% or less.
- Rare earth elements and Ca are effective elements for improving high-temperature oxidation resistance, and one or more of them can be added as necessary. In that case, it is effective to secure a content of 0.001% by mass or more for rare earth elements and 0.0005% by mass or more for Ca. However, since the toughness decreases when a large amount of these elements are added, it is necessary to perform the addition within a range of contents of 0.100% by mass or less when adding rare earth elements and 0.0050% by mass or less when adding Ca. There is.
- Fe and inevitable impurities The balance which is a component other than the above consists of Fe and inevitable impurities.
- the inevitable impurities mean impurity elements that cannot be mixed into the material during the manufacturing process. Inevitable impurities are not particularly limited.
- Nb carbonitride carbbide / nitride
- Laves phase are precipitates generated by hot rolling. If C and N are present in a solid solution state in the steel, the toughness of the hot-rolled steel sheet is lowered, so it is effective to precipitate C and N as Nb carbonitride. In addition, by precipitating Nb carbonitride, Nb dissolved in the steel is reduced, and the amount of Laves phase precipitation that lowers the toughness of the hot-rolled steel sheet can be reduced.
- the amount of precipitation of Nb carbonitride needs to be 0.2% by mass or more. Further, it is necessary to make 10 or less Laves phases having a particle size of 0.1 ⁇ m or less per 10 ⁇ m 2 area.
- the precipitation amount (% by mass) of Nb carbonitride is 10% by mass of acetylacetone + 1% by mass of tetramethylammonium chloride + 89% by mass of methyl alcohol, and is ⁇
- the residue of the precipitate was subjected to electrolytic extraction at an SCE potential of 100 mV to 400 mV, and then the extracted residue was filtered through a 0.2 ⁇ m micropore filter, and calculated from the ratio of the weight to the total dissolved weight.
- the Laves phase a surface photograph was taken using a scanning electron microscope (SEM), the size of the Laves phase was measured, and the number of Laves phases having a particle size of 0.1 ⁇ m or less per 10 ⁇ m 2 area was determined. Measured. The number of Laves phases was measured at at least 5 points and the average value was taken.
- the thickness of the hot-rolled steel sheet of the present invention is not particularly limited as long as it is appropriately set depending on the application.
- the thickness of the hot-rolled steel sheet is generally 5.0 mm to 11.0 mm, preferably 5.5 mm to 9.0 mm.
- it is an index of workability of Nb-containing ferritic stainless steel cold-rolled steel sheets (hereinafter sometimes abbreviated as “cold-rolled steel sheets”).
- the thickness of the hot-rolled steel sheet is usually more than 4.5 mm and not more than 10.00 mm.
- the thickness of the hot-rolled steel sheet is preferably 5.0 mm to 9.0 mm, more preferably 5.5 mm to 8.0 mm.
- the Nb-containing ferritic stainless steel hot-rolled steel sheet of the present invention having the above-described characteristics is 1000 ° C. to 1100 ° C. when hot rolling a stainless steel slab having the same composition as the Nb-containing ferritic stainless steel hot-rolled steel sheet.
- the finish hot rolling temperature is set to 850 ° C. or higher, and after the hot rolling, winding is performed at a winding temperature of 550 ° C. or lower.
- the heating temperature of the stainless steel slab is not particularly limited, but is preferably 1200 ° C to 1300 ° C.
- the heating temperature of the stainless steel slab is less than 1200 ° C., distortion due to hot rolling is excessively introduced, and subsequent structure control becomes difficult, and surface scratches may become a problem.
- the heating temperature of the stainless steel slab exceeds 1300 ° C., the structure becomes coarse and a hot-rolled steel sheet having desired characteristics may not be obtained.
- Hot rolling typically includes multiple passes of coarse hot rolling and multiple passes of finish hot rolling.
- the temperature is maintained at 1000 ° C. to 1100 ° C. for 60 seconds or more, and the finish hot rolling temperature is 850 ° C. or more. It is necessary to.
- the holding temperature is set to 1000 ° C. to 1100 ° C. is that the precipitation temperature of Nb carbonitride is 1100 ° C. or less, and in particular, the precipitation of Nb carbonitride is efficiently promoted by setting the holding temperature. It is because it can do.
- Nb carbonitride is not sufficiently precipitated.
- the finish hot rolling temperature is less than 850 ° C.
- the Laves phase precipitation temperature is around 800 ° C., and thus Laves phase precipitation cannot be sufficiently reduced.
- the method of holding at a temperature of 1000 ° C. to 1100 ° C. for 60 seconds or more is not particularly limited, and it is sufficient to reduce the sheet passing speed or introduce a delay before finish rolling.
- the timing of holding at a temperature of 1000 ° C. to 1100 ° C. for 60 seconds or more is not particularly limited as long as it is during the hot rolling process, but it is preferably performed from the end of rough hot rolling to the initial stage of finish hot rolling.
- the finishing hot rolling time is not particularly limited, and can be set according to a hot rolling method known in the technical field. Generally, the finish hot rolling time is determined in consideration of the balance with the total time of the hot rolling process, but as the finish hot rolling time is longer, the amount of precipitation of Nb carbonitride increases.
- the coil After hot rolling, the coil is wound at a winding temperature of 550 ° C. or lower.
- a Laves phase may precipitate and the toughness may be lowered.
- the hot-rolled steel sheet obtained as described above has sufficiently increased the precipitation amount of Nb carbonitride in the hot-rolling step, Laves can be obtained even when the precipitation temperature of Laves phase (around 800 ° C.) is reached. The phase is difficult to precipitate. For this reason, there is little need to use a technique in which the hot-rolled steel sheet is rapidly cooled by water cooling or the like to shorten the transit time of the Laves phase precipitation temperature.
- the cold-rolled steel sheet of the present invention has a feature that the r value is 1.2 or more in addition to the characteristics of the hot-rolled steel sheet. Therefore, the cold-rolled steel sheet of the present invention is excellent in workability, and by performing various processes, it is possible to manufacture automobile exhaust pipe parts such as an exhaust manifold, a front pipe, a center pipe, and a catalytic converter outer cylinder.
- the cold-rolled steel sheet of the present invention having the above-described characteristics can be manufactured by annealing the hot-rolled steel sheet and then cold-rolling and annealing at a rolling reduction of 70% or more. Prior to cold rolling, the hot rolled steel sheet is annealed.
- Annealing is performed at a temperature at which a recrystallized structure is obtained.
- the annealing temperature may be appropriately set according to the composition of the hot-rolled steel sheet and is not particularly limited, but is usually 950 ° C. to 1150 ° C. When the annealing temperature is less than 950 ° C., a recrystallized structure may not be obtained. On the other hand, when the annealing temperature exceeds 1150 ° C., the crystal grains may become coarse.
- Cold rolling is performed at a rolling reduction of 70% or more in order to increase the r value of the cold rolled steel sheet to 1.2 or more. When the rolling reduction is less than 70%, the r value of the cold-rolled steel sheet is less than 1.2.
- the cold rolled steel sheet is annealed. Annealing is performed at a temperature at which a recrystallized structure is obtained.
- the annealing temperature may be appropriately set according to the composition of the cold rolled steel sheet, and is not particularly limited, but is usually 1000 ° C. to 1100 ° C. When the annealing temperature is less than 1000 ° C., a recrystallized structure may not be obtained. When the annealing temperature exceeds 1100 ° C., the crystal grains are coarsened, and the surface may be roughened during processing to cause cracking.
- Nb-containing ferritic stainless steel hot-rolled steel sheets have a Nb carbonitride precipitation amount of 0.2% by mass or more and 10 or less Laves phases with a particle size of 0.1 ⁇ m or less per 10 ⁇ m 2 area, and are tough. It was confirmed to be excellent.
- the holding time at a temperature of 1000 ° C. to 1100 ° C. was too short. It was found that 9 to 12 Nb-containing ferritic stainless steel hot-rolled steel sheets had a small amount of Nb carbonitride and a large amount of Laves phase and were not sufficiently tough.
- Nb-containing ferritic stainless steel hot-rolled steel sheets were annealed, then cold-rolled, and further annealed to obtain Nb-containing ferritic stainless steel cold-rolled steel sheets.
- the manufacturing conditions at this time are shown in Table 3.
- No. Nb-containing ferritic stainless steel hot rolled steel sheets of 9 to 12 had low toughness and could not be cold rolled.
- r value was calculated
- the r value is an average r value using the following formula (1) and the following formula (2) after collecting a JIS No. 13 B tensile test piece from an Nb-containing ferritic stainless steel cold-rolled steel sheet and applying a 14.4% strain.
- Nb-containing ferritic stainless steel cold-rolled steel sheets 1 to 5 and 7 have an r value of 1.2 or more and were confirmed to be excellent in workability.
- No. cold-rolled with a rolling reduction of less than 70% No. 6 Nb-containing ferritic stainless steel cold-rolled steel sheet had an r value of less than 1.2, indicating that workability was not sufficient.
- the present invention it is possible to provide an Nb-containing ferritic stainless steel hot rolled steel sheet excellent in toughness and workability and a method for producing the same. Moreover, according to this invention, the Nb containing ferritic stainless steel cold-rolled steel plate excellent in workability and its manufacturing method can be provided.
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Abstract
This hot rolled Nb-containing ferritic stainless steel sheet has a composition that contains 0.030% by mass or less of C, 2.00% by mass or less of Si, 2.00% by mass or less of Mn, 0.050% by mass or less of P, 0.040% by mass or less of S, from 10.00% by mass to 25.00% by mass of Cr, 0.030% by mass or less of N and from 0.01% by mass to 0.80% by mass of Nb, with the balance made up of Fe and unavoidable impurities. With respect to this hot rolled Nb-containing ferritic stainless steel sheet, the precipitation amount of Nb carbonitrides is 0.2% by mass or more, and 10 or less Laves phases having a particle diameter of 0.1 μm or less are present per area of 10 μm2.
Description
本発明は、Ｎｂ含有フェライト系ステンレス熱延鋼板及びその製造方法、並びにＮｂ含有フェライト系ステンレス冷延鋼板及びその製造方法に関する。特に、本発明は、排気管フランジ部品及び排気管部品を製造するために用いられるＮｂ含有フェライト系ステンレス熱延鋼板及びその製造方法、並びにＮｂ含有フェライト系ステンレス冷延鋼板及びその製造方法に関する。
The present invention relates to an Nb-containing ferritic stainless steel hot-rolled steel sheet and a manufacturing method thereof, and an Nb-containing ferritic stainless steel cold-rolled steel sheet and a manufacturing method thereof. In particular, the present invention relates to an Nb-containing ferritic stainless steel hot-rolled steel sheet and a method for manufacturing the same, and an Nb-containing ferritic stainless steel cold-rolled steel sheet and a method for manufacturing the same.
排気管フランジ部品及び排気管部品には耐食性、耐熱性及び強度などの特性が要求されるため、このような特性に優れるステンレス鋼板が素材として用いられている。ここで、排気管部品とは、内部を排気ガスが流通可能な部品のことを意味し、特に、自動車におけるエキゾーストマニホールド、フロントパイプ、センターパイプ、触媒コンバータ外筒などの部品を意味する。また、排気管フランジ部品とは、排気管部品の端部に溶接接合され、当該排気管部品と他の部品との締結機能を担うフランジ部を構成する部品を意味する。
従来、ステンレス鋼板としては、製造性が良好なオーステナイト系ステンレス鋼板が一般に用いられてきたけれども、熱膨張係数及びコストの面で有利なフェライト系ステンレス鋼板への置き換えが進んでいる。このようなフェライト系ステンレス鋼板としては、Ｎｂ含有フェライト系ステンレス鋼板が挙げられる。 Since exhaust pipe flange parts and exhaust pipe parts are required to have characteristics such as corrosion resistance, heat resistance and strength, a stainless steel plate having excellent such characteristics is used as a material. Here, the exhaust pipe part means a part through which exhaust gas can flow, and particularly means parts such as an exhaust manifold, a front pipe, a center pipe, and a catalytic converter outer cylinder in an automobile. Further, the exhaust pipe flange part means a part that constitutes a flange part that is welded and joined to an end part of the exhaust pipe part and that bears a fastening function between the exhaust pipe part and another part.
Conventionally, an austenitic stainless steel plate having good manufacturability has been generally used as the stainless steel plate, but replacement with a ferritic stainless steel plate advantageous in terms of thermal expansion coefficient and cost is progressing. Examples of such a ferritic stainless steel plate include an Nb-containing ferritic stainless steel plate.
従来、ステンレス鋼板としては、製造性が良好なオーステナイト系ステンレス鋼板が一般に用いられてきたけれども、熱膨張係数及びコストの面で有利なフェライト系ステンレス鋼板への置き換えが進んでいる。このようなフェライト系ステンレス鋼板としては、Ｎｂ含有フェライト系ステンレス鋼板が挙げられる。 Since exhaust pipe flange parts and exhaust pipe parts are required to have characteristics such as corrosion resistance, heat resistance and strength, a stainless steel plate having excellent such characteristics is used as a material. Here, the exhaust pipe part means a part through which exhaust gas can flow, and particularly means parts such as an exhaust manifold, a front pipe, a center pipe, and a catalytic converter outer cylinder in an automobile. Further, the exhaust pipe flange part means a part that constitutes a flange part that is welded and joined to an end part of the exhaust pipe part and that bears a fastening function between the exhaust pipe part and another part.
Conventionally, an austenitic stainless steel plate having good manufacturability has been generally used as the stainless steel plate, but replacement with a ferritic stainless steel plate advantageous in terms of thermal expansion coefficient and cost is progressing. Examples of such a ferritic stainless steel plate include an Nb-containing ferritic stainless steel plate.
排気管フランジ部品は、熱延鋼板を冷間鍛造することによって製造される。また、排気管フランジ部品は、排気管部品の端部に対応する穴、ボトル締結用の穴を有し、切削加工も施されているのが一般的である。そのため、排気管フランジ部品の製造に用いられる熱延鋼板には加工性が要求される。
また、排気管部品は、一般に、冷延鋼板をプレス加工したり、冷延鋼板をパイプ加工した後に種々の加工を行ったりすることによって製造される。そのため、排気管部品の製造に用いられる冷延鋼板にも加工性が要求される。特に、近年の排気管部品（特に、エキゾーストマニホールド）の小型化に伴い、冷延鋼板の加工性の更なる向上が望まれている。冷延鋼板の加工性はランクフォード値（以下、「ｒ値」という。）を指標として表すことができ、ｒ値を向上させるためには、冷延圧下率を大きくすることが有効である。
しかしながら、Ｎｂ含有フェライト系ステンレス鋼板は、熱延時にラーベス相（Ｆｅ2Ｎｂを主体とする金属間化合物）が生成して靱性低下を起こし易い。また、本来フェライト系ステンレス鋼板は、４７５℃脆化が起こり易い。そのため、厚ゲージ（５ｍｍ～１０ｍｍ）のＮｂ含有フェライト系ステンレス熱延鋼板を製造し、これを冷延すると、割れが発生し易く、冷延圧下率を大きくすることが難しい。 The exhaust pipe flange part is manufactured by cold forging a hot-rolled steel sheet. Further, the exhaust pipe flange part generally has a hole corresponding to the end of the exhaust pipe part, a hole for fastening the bottle, and is also subjected to cutting. Therefore, workability is required for the hot-rolled steel sheet used for manufacturing the exhaust pipe flange part.
Further, the exhaust pipe component is generally manufactured by pressing a cold-rolled steel sheet or performing various processes after pipe-working the cold-rolled steel sheet. For this reason, workability is also required for cold-rolled steel sheets used in the manufacture of exhaust pipe components. In particular, with the recent downsizing of exhaust pipe components (particularly, exhaust manifolds), further improvement in workability of cold-rolled steel sheets is desired. The workability of a cold-rolled steel sheet can be expressed by using a Rankford value (hereinafter referred to as “r value”) as an index. In order to improve the r value, it is effective to increase the cold rolling reduction ratio.
However, the Nb-containing ferritic stainless steel sheet is liable to cause a decrease in toughness due to the formation of a Laves phase (intermetallic compound mainly composed of Fe 2 Nb) during hot rolling. In addition, ferritic stainless steel sheets are inherently susceptible to embrittlement at 475 ° C. For this reason, when a Nb-containing ferritic stainless steel hot-rolled steel sheet having a thickness gauge (5 mm to 10 mm) is manufactured and cold-rolled, cracks are likely to occur and it is difficult to increase the cold rolling reduction ratio.
また、排気管部品は、一般に、冷延鋼板をプレス加工したり、冷延鋼板をパイプ加工した後に種々の加工を行ったりすることによって製造される。そのため、排気管部品の製造に用いられる冷延鋼板にも加工性が要求される。特に、近年の排気管部品（特に、エキゾーストマニホールド）の小型化に伴い、冷延鋼板の加工性の更なる向上が望まれている。冷延鋼板の加工性はランクフォード値（以下、「ｒ値」という。）を指標として表すことができ、ｒ値を向上させるためには、冷延圧下率を大きくすることが有効である。
しかしながら、Ｎｂ含有フェライト系ステンレス鋼板は、熱延時にラーベス相（Ｆｅ2Ｎｂを主体とする金属間化合物）が生成して靱性低下を起こし易い。また、本来フェライト系ステンレス鋼板は、４７５℃脆化が起こり易い。そのため、厚ゲージ（５ｍｍ～１０ｍｍ）のＮｂ含有フェライト系ステンレス熱延鋼板を製造し、これを冷延すると、割れが発生し易く、冷延圧下率を大きくすることが難しい。 The exhaust pipe flange part is manufactured by cold forging a hot-rolled steel sheet. Further, the exhaust pipe flange part generally has a hole corresponding to the end of the exhaust pipe part, a hole for fastening the bottle, and is also subjected to cutting. Therefore, workability is required for the hot-rolled steel sheet used for manufacturing the exhaust pipe flange part.
Further, the exhaust pipe component is generally manufactured by pressing a cold-rolled steel sheet or performing various processes after pipe-working the cold-rolled steel sheet. For this reason, workability is also required for cold-rolled steel sheets used in the manufacture of exhaust pipe components. In particular, with the recent downsizing of exhaust pipe components (particularly, exhaust manifolds), further improvement in workability of cold-rolled steel sheets is desired. The workability of a cold-rolled steel sheet can be expressed by using a Rankford value (hereinafter referred to as “r value”) as an index. In order to improve the r value, it is effective to increase the cold rolling reduction ratio.
However, the Nb-containing ferritic stainless steel sheet is liable to cause a decrease in toughness due to the formation of a Laves phase (intermetallic compound mainly composed of Fe 2 Nb) during hot rolling. In addition, ferritic stainless steel sheets are inherently susceptible to embrittlement at 475 ° C. For this reason, when a Nb-containing ferritic stainless steel hot-rolled steel sheet having a thickness gauge (5 mm to 10 mm) is manufactured and cold-rolled, cracks are likely to occur and it is difficult to increase the cold rolling reduction ratio.
Ｎｂ含有フェライト系ステンレス熱延鋼板の靱性を向上させる方法としては、例えば、Ｃ及びＮの合計量を特定の範囲に制御することにより、ラーベス相の生成を抑制する手法が特許文献１に提案されている。
また、Ｎｂ含有フェライト系ステンレス冷延鋼板の加工性を向上させる方法としては、例えば、熱延仕上開始温度、終了温度及び熱延板焼鈍温度などを制御する手法が特許文献２に提案されている。 As a method for improving the toughness of the Nb-containing ferritic stainless steel hot-rolled steel sheet, for example, a method for suppressing the generation of Laves phase by controlling the total amount of C and N within a specific range is proposed in Patent Document 1. ing.
Moreover, as a method for improving the workability of the Nb-containing ferritic stainless steel cold-rolled steel sheet, for example, a method for controlling the hot-rolling finishing start temperature, the end temperature, the hot-rolled sheet annealing temperature, and the like is proposed in Patent Document 2. .
また、Ｎｂ含有フェライト系ステンレス冷延鋼板の加工性を向上させる方法としては、例えば、熱延仕上開始温度、終了温度及び熱延板焼鈍温度などを制御する手法が特許文献２に提案されている。 As a method for improving the toughness of the Nb-containing ferritic stainless steel hot-rolled steel sheet, for example, a method for suppressing the generation of Laves phase by controlling the total amount of C and N within a specific range is proposed in Patent Document 1. ing.
Moreover, as a method for improving the workability of the Nb-containing ferritic stainless steel cold-rolled steel sheet, for example, a method for controlling the hot-rolling finishing start temperature, the end temperature, the hot-rolled sheet annealing temperature, and the like is proposed in Patent Document 2. .
しかしながら、特許文献１の手法は、板厚が４．５ｍｍ程度のＮｂ含有フェライト系ステンレス熱延鋼板を対象としており、厚ゲージのＮｂ含有フェライト系ステンレス熱延鋼板に対してはラーベス相の生成を十分に抑制することができない。
また、特許文献２の手法を用いたとしても、Ｎｂ含有フェライト系ステンレス冷延鋼板の加工性が十分に確保されないという問題がある。
本発明は、上記のような問題を解決するためになされたものであり、靱性及び加工性に優れたＮｂ含有フェライト系ステンレス熱延鋼板及びその製造方法を提供することを目的とする。
また、本発明は、加工性に優れたＮｂ含有フェライト系ステンレス冷延鋼板及びその製造方法を提供することを目的とする。 However, the method of Patent Document 1 is directed to a Nb-containing ferritic stainless steel hot-rolled steel sheet having a thickness of about 4.5 mm, and a Laves phase is generated for a thick gauge Nb-containing ferritic stainless steel hot-rolled steel sheet. It cannot be suppressed sufficiently.
Moreover, even if it uses the method of patent document 2, there exists a problem that workability of a Nb containing ferritic stainless steel cold-rolled steel plate is not fully ensured.
The present invention has been made to solve the above problems, and an object of the present invention is to provide a Nb-containing ferritic stainless steel hot rolled steel sheet excellent in toughness and workability and a method for producing the same.
Another object of the present invention is to provide an Nb-containing ferritic stainless steel cold-rolled steel sheet excellent in workability and a method for producing the same.
また、特許文献２の手法を用いたとしても、Ｎｂ含有フェライト系ステンレス冷延鋼板の加工性が十分に確保されないという問題がある。
本発明は、上記のような問題を解決するためになされたものであり、靱性及び加工性に優れたＮｂ含有フェライト系ステンレス熱延鋼板及びその製造方法を提供することを目的とする。
また、本発明は、加工性に優れたＮｂ含有フェライト系ステンレス冷延鋼板及びその製造方法を提供することを目的とする。 However, the method of Patent Document 1 is directed to a Nb-containing ferritic stainless steel hot-rolled steel sheet having a thickness of about 4.5 mm, and a Laves phase is generated for a thick gauge Nb-containing ferritic stainless steel hot-rolled steel sheet. It cannot be suppressed sufficiently.
Moreover, even if it uses the method of patent document 2, there exists a problem that workability of a Nb containing ferritic stainless steel cold-rolled steel plate is not fully ensured.
The present invention has been made to solve the above problems, and an object of the present invention is to provide a Nb-containing ferritic stainless steel hot rolled steel sheet excellent in toughness and workability and a method for producing the same.
Another object of the present invention is to provide an Nb-containing ferritic stainless steel cold-rolled steel sheet excellent in workability and a method for producing the same.
本発明者は、上記の問題を解決すべく鋭意研究を続けた結果、特定の組成を有するステンレス鋼スラブを熱延する際に、１１００℃～１０００℃の温度で６０秒以上保持すると共に仕上熱延温度を８５０℃以上とし、熱延後に５５０℃以下の巻取温度で巻取ることによってＮｂ炭窒化物及びラーベス相の量を適正範囲に制御することができ、その結果としてＮｂ含有フェライト系ステンレス熱延鋼板の靱性が向上することを見出し、本発明を完成するに至った。
また、本発明者らは、このＮｂ含有フェライト系ステンレス熱延鋼板を焼鈍した後、７０％以上の圧下率で冷延して焼鈍することによってｒ値を１．２以上に高めることができ、その結果としてＮｂ含有フェライト系ステンレス冷延鋼板の加工性が向上することを見出し、本発明を完成するに至った。 As a result of intensive studies to solve the above problems, the present inventor, when hot-rolling a stainless steel slab having a specific composition, keeps it at a temperature of 1100 ° C. to 1000 ° C. for 60 seconds or more and finishes heat. The amount of Nb carbonitride and Laves phase can be controlled within an appropriate range by setting the rolling temperature to 850 ° C. or more and winding at a winding temperature of 550 ° C. or less after hot rolling. As a result, Nb-containing ferritic stainless steel The present inventors have found that the toughness of the hot-rolled steel sheet is improved and have completed the present invention.
In addition, the present inventors can increase the r value to 1.2 or more by annealing the Nb-containing ferritic stainless steel hot-rolled steel sheet, followed by cold rolling at a rolling reduction of 70% or more and annealing. As a result, it has been found that the workability of the Nb-containing ferritic stainless steel cold-rolled steel sheet is improved, and the present invention has been completed.
また、本発明者らは、このＮｂ含有フェライト系ステンレス熱延鋼板を焼鈍した後、７０％以上の圧下率で冷延して焼鈍することによってｒ値を１．２以上に高めることができ、その結果としてＮｂ含有フェライト系ステンレス冷延鋼板の加工性が向上することを見出し、本発明を完成するに至った。 As a result of intensive studies to solve the above problems, the present inventor, when hot-rolling a stainless steel slab having a specific composition, keeps it at a temperature of 1100 ° C. to 1000 ° C. for 60 seconds or more and finishes heat. The amount of Nb carbonitride and Laves phase can be controlled within an appropriate range by setting the rolling temperature to 850 ° C. or more and winding at a winding temperature of 550 ° C. or less after hot rolling. As a result, Nb-containing ferritic stainless steel The present inventors have found that the toughness of the hot-rolled steel sheet is improved and have completed the present invention.
In addition, the present inventors can increase the r value to 1.2 or more by annealing the Nb-containing ferritic stainless steel hot-rolled steel sheet, followed by cold rolling at a rolling reduction of 70% or more and annealing. As a result, it has been found that the workability of the Nb-containing ferritic stainless steel cold-rolled steel sheet is improved, and the present invention has been completed.
すなわち、本発明は、Ｃ：０．０３０質量％以下、Ｓｉ：２．００質量％以下、Ｍｎ：２．００質量％以下、Ｐ：０．０５０質量％以下、Ｓ：０．０４０質量％以下、Ｃｒ：１０．００質量％～２５．００質量％、Ｎ：０．０３０質量％以下、Ｎｂ：０．０１質量％～０．８０質量％を含有し、残部がＦｅ及び不可避的不純物からなる組成を有するＮｂ含有フェライト系ステンレス熱延鋼板であって、Ｎｂ炭窒化物の析出量が０．２質量％以上であり、且つ粒径０．１μｍ以下のラーベス相が面積１０μｍ2あたり１０個以下であることを特徴とするＮｂ含有フェライト系ステンレス熱延鋼板である。
また、本発明は、Ｃ：０．０３０質量％以下、Ｓｉ：２．００質量％以下、Ｍｎ：２．００質量％以下、Ｐ：０．０５０質量％以下、Ｓ：０．０４０質量％以下、Ｃｒ：１０．００質量％～２５．００質量％、Ｎ：０．０３０質量％以下、Ｎｂ：０．０１質量％～０．８０質量％を含有し、残部がＦｅ及び不可避的不純物からなる組成を有するステンレス鋼スラブを熱延する際に、１０００℃～１１００℃の温度で６０秒以上保持すると共に仕上熱延温度を８５０℃以上とし、熱延後に５５０℃以下の巻取温度で巻取ることを特徴とするＮｂ含有フェライト系ステンレス熱延鋼板の製造方法である。 That is, the present invention is C: 0.030 mass% or less, Si: 2.00 mass% or less, Mn: 2.00 mass% or less, P: 0.050 mass% or less, S: 0.040 mass% or less. Cr: 10.00% by mass to 25.00% by mass, N: 0.030% by mass or less, Nb: 0.01% by mass to 0.80% by mass, with the balance being Fe and inevitable impurities A Nb-containing ferritic stainless steel hot-rolled steel sheet having a composition, wherein the precipitation amount of Nb carbonitride is 0.2% by mass or more, and 10 or less Laves phases having a particle size of 0.1 μm or less per 10 μm 2 area It is a Nb-containing ferritic stainless steel hot-rolled steel sheet.
In the present invention, C: 0.030 mass% or less, Si: 2.00 mass% or less, Mn: 2.00 mass% or less, P: 0.050 mass% or less, S: 0.040 mass% or less Cr: 10.00% by mass to 25.00% by mass, N: 0.030% by mass or less, Nb: 0.01% by mass to 0.80% by mass, with the balance being Fe and inevitable impurities When hot-rolling a stainless steel slab having a composition, it is held at a temperature of 1000 ° C. to 1100 ° C. for 60 seconds or longer, and the finish hot rolling temperature is set to 850 ° C. or higher, and is wound at a winding temperature of 550 ° C. or lower after hot rolling. This is a method for producing a Nb-containing ferritic stainless steel hot-rolled steel sheet.
また、本発明は、Ｃ：０．０３０質量％以下、Ｓｉ：２．００質量％以下、Ｍｎ：２．００質量％以下、Ｐ：０．０５０質量％以下、Ｓ：０．０４０質量％以下、Ｃｒ：１０．００質量％～２５．００質量％、Ｎ：０．０３０質量％以下、Ｎｂ：０．０１質量％～０．８０質量％を含有し、残部がＦｅ及び不可避的不純物からなる組成を有するステンレス鋼スラブを熱延する際に、１０００℃～１１００℃の温度で６０秒以上保持すると共に仕上熱延温度を８５０℃以上とし、熱延後に５５０℃以下の巻取温度で巻取ることを特徴とするＮｂ含有フェライト系ステンレス熱延鋼板の製造方法である。 That is, the present invention is C: 0.030 mass% or less, Si: 2.00 mass% or less, Mn: 2.00 mass% or less, P: 0.050 mass% or less, S: 0.040 mass% or less. Cr: 10.00% by mass to 25.00% by mass, N: 0.030% by mass or less, Nb: 0.01% by mass to 0.80% by mass, with the balance being Fe and inevitable impurities A Nb-containing ferritic stainless steel hot-rolled steel sheet having a composition, wherein the precipitation amount of Nb carbonitride is 0.2% by mass or more, and 10 or less Laves phases having a particle size of 0.1 μm or less per 10 μm 2 area It is a Nb-containing ferritic stainless steel hot-rolled steel sheet.
In the present invention, C: 0.030 mass% or less, Si: 2.00 mass% or less, Mn: 2.00 mass% or less, P: 0.050 mass% or less, S: 0.040 mass% or less Cr: 10.00% by mass to 25.00% by mass, N: 0.030% by mass or less, Nb: 0.01% by mass to 0.80% by mass, with the balance being Fe and inevitable impurities When hot-rolling a stainless steel slab having a composition, it is held at a temperature of 1000 ° C. to 1100 ° C. for 60 seconds or longer, and the finish hot rolling temperature is set to 850 ° C. or higher, and is wound at a winding temperature of 550 ° C. or lower after hot rolling. This is a method for producing a Nb-containing ferritic stainless steel hot-rolled steel sheet.
また、本発明は、Ｃ：０．０３０質量％以下、Ｓｉ：２．００質量％以下、Ｍｎ：２．００質量％以下、Ｐ：０．０５０質量％以下、Ｓ：０．０４０質量％以下、Ｃｒ：１０．００質量％～２５．００質量％、Ｎ：０．０３０質量％以下、Ｎｂ：０．０１質量％～０．８０質量％を含有し、残部がＦｅ及び不可避的不純物からなる組成を有するＮｂ含有フェライト系ステンレス冷延鋼板であって、Ｎｂ炭窒化物の析出量が０．２質量％以上であり、粒径０．１μｍ以下のラーベス相が面積１０μｍ2あたり１０個以下であり、且つｒ値が１．２以上であることを特徴とするＮｂ含有フェライト系ステンレス冷延鋼板である。
さらに、本発明は、上記のＮｂ含有フェライト系ステンレス熱延鋼板を焼鈍した後、７０％以上の圧下率で冷延して焼鈍することを特徴とするＮｂ含有フェライト系ステンレス冷延鋼板の製造方法である。 In the present invention, C: 0.030 mass% or less, Si: 2.00 mass% or less, Mn: 2.00 mass% or less, P: 0.050 mass% or less, S: 0.040 mass% or less Cr: 10.00% by mass to 25.00% by mass, N: 0.030% by mass or less, Nb: 0.01% by mass to 0.80% by mass, with the balance being Fe and inevitable impurities An Nb-containing ferritic stainless steel cold-rolled steel sheet having a composition, wherein the precipitation amount of Nb carbonitride is 0.2% by mass or more, and there are 10 or less Laves phases having a particle size of 0.1 μm or less per 10 μm 2 area. The Nb-containing ferritic stainless steel cold-rolled steel sheet has an r value of 1.2 or more.
Furthermore, the present invention provides a method for producing an Nb-containing ferritic stainless steel cold-rolled steel sheet, characterized by annealing the Nb-containing ferritic stainless steel hot-rolled steel sheet, followed by cold rolling at a rolling reduction of 70% or more. It is.
さらに、本発明は、上記のＮｂ含有フェライト系ステンレス熱延鋼板を焼鈍した後、７０％以上の圧下率で冷延して焼鈍することを特徴とするＮｂ含有フェライト系ステンレス冷延鋼板の製造方法である。 In the present invention, C: 0.030 mass% or less, Si: 2.00 mass% or less, Mn: 2.00 mass% or less, P: 0.050 mass% or less, S: 0.040 mass% or less Cr: 10.00% by mass to 25.00% by mass, N: 0.030% by mass or less, Nb: 0.01% by mass to 0.80% by mass, with the balance being Fe and inevitable impurities An Nb-containing ferritic stainless steel cold-rolled steel sheet having a composition, wherein the precipitation amount of Nb carbonitride is 0.2% by mass or more, and there are 10 or less Laves phases having a particle size of 0.1 μm or less per 10 μm 2 area. The Nb-containing ferritic stainless steel cold-rolled steel sheet has an r value of 1.2 or more.
Furthermore, the present invention provides a method for producing an Nb-containing ferritic stainless steel cold-rolled steel sheet, characterized by annealing the Nb-containing ferritic stainless steel hot-rolled steel sheet, followed by cold rolling at a rolling reduction of 70% or more. It is.
本発明によれば、靱性及び加工性に優れたＮｂ含有フェライト系ステンレス熱延鋼板及びその製造方法を提供することができる。
また、本発明によれば、加工性に優れたＮｂ含有フェライト系ステンレス冷延鋼板及びその製造方法を提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the Nb containing ferritic stainless steel hot-rolled steel plate excellent in toughness and workability, and its manufacturing method can be provided.
Moreover, according to this invention, the Nb containing ferritic stainless steel cold-rolled steel plate excellent in workability and its manufacturing method can be provided.
また、本発明によれば、加工性に優れたＮｂ含有フェライト系ステンレス冷延鋼板及びその製造方法を提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the Nb containing ferritic stainless steel hot-rolled steel plate excellent in toughness and workability, and its manufacturing method can be provided.
Moreover, according to this invention, the Nb containing ferritic stainless steel cold-rolled steel plate excellent in workability and its manufacturing method can be provided.
＜Ｎｂ含有フェライト系ステンレス熱延鋼板＞
本発明のＮｂ含有フェライト系ステンレス熱延鋼板（以下、「熱延鋼板」と略すことがある。）は、Ｃ、Ｓｉ、Ｍｎ、Ｐ、Ｓ、Ｃｒ、Ｎ、Ｎｂを含有し、残部がＦｅ及び不可避的不純物からなる組成を有する。また、本発明の熱延鋼板は、Ｎｉ、Ｍｏ、Ｃｕ、Ｃｏ、Ａｌ、Ｗ、Ｖ、Ｔｉ、Ｚｒ、Ｂ、希土類元素、Ｃａの１種以上をさらに含有する組成を有していてもよい。
以下、本発明の熱延鋼板について詳細に説明する。 <Nb-containing ferritic stainless steel hot-rolled steel sheet>
The Nb-containing ferritic stainless steel hot-rolled steel sheet of the present invention (hereinafter sometimes abbreviated as “hot-rolled steel sheet”) contains C, Si, Mn, P, S, Cr, N, and Nb, with the balance being Fe. And a composition comprising inevitable impurities. The hot-rolled steel sheet of the present invention may have a composition further containing one or more of Ni, Mo, Cu, Co, Al, W, V, Ti, Zr, B, rare earth elements, and Ca. .
Hereinafter, the hot-rolled steel sheet of the present invention will be described in detail.
本発明のＮｂ含有フェライト系ステンレス熱延鋼板（以下、「熱延鋼板」と略すことがある。）は、Ｃ、Ｓｉ、Ｍｎ、Ｐ、Ｓ、Ｃｒ、Ｎ、Ｎｂを含有し、残部がＦｅ及び不可避的不純物からなる組成を有する。また、本発明の熱延鋼板は、Ｎｉ、Ｍｏ、Ｃｕ、Ｃｏ、Ａｌ、Ｗ、Ｖ、Ｔｉ、Ｚｒ、Ｂ、希土類元素、Ｃａの１種以上をさらに含有する組成を有していてもよい。
以下、本発明の熱延鋼板について詳細に説明する。 <Nb-containing ferritic stainless steel hot-rolled steel sheet>
The Nb-containing ferritic stainless steel hot-rolled steel sheet of the present invention (hereinafter sometimes abbreviated as “hot-rolled steel sheet”) contains C, Si, Mn, P, S, Cr, N, and Nb, with the balance being Fe. And a composition comprising inevitable impurities. The hot-rolled steel sheet of the present invention may have a composition further containing one or more of Ni, Mo, Cu, Co, Al, W, V, Ti, Zr, B, rare earth elements, and Ca. .
Hereinafter, the hot-rolled steel sheet of the present invention will be described in detail.
＜Ｃ：０．０３０質量％以下＞
Ｃは、鋼を硬質化させ、熱延鋼板の靱性を低下させる要因となる。そのため、Ｃの含有量は０．０３０質量％以下に制限される。ただし、Ｃの含有量を極度に低下させる必要はなく、一般に０．００１質量％～０．０３０質量％、好ましくは０．００３質量％～０．０２５質量％、より好ましくは０．００５質量％～０．０２０質量％のＣ含有量とすればよい。 <C: 0.030% by mass or less>
C is a factor that hardens the steel and lowers the toughness of the hot-rolled steel sheet. Therefore, the C content is limited to 0.030% by mass or less. However, it is not necessary to extremely reduce the C content, and generally 0.001% to 0.030% by weight, preferably 0.003% to 0.025% by weight, and more preferably 0.005% by weight. A C content of ˜0.020 mass% may be used.
Ｃは、鋼を硬質化させ、熱延鋼板の靱性を低下させる要因となる。そのため、Ｃの含有量は０．０３０質量％以下に制限される。ただし、Ｃの含有量を極度に低下させる必要はなく、一般に０．００１質量％～０．０３０質量％、好ましくは０．００３質量％～０．０２５質量％、より好ましくは０．００５質量％～０．０２０質量％のＣ含有量とすればよい。 <C: 0.030% by mass or less>
C is a factor that hardens the steel and lowers the toughness of the hot-rolled steel sheet. Therefore, the C content is limited to 0.030% by mass or less. However, it is not necessary to extremely reduce the C content, and generally 0.001% to 0.030% by weight, preferably 0.003% to 0.025% by weight, and more preferably 0.005% by weight. A C content of ˜0.020 mass% may be used.
＜Ｓｉ：２．００質量％以下、Ｍｎ：２．００質量％以下＞
Ｓｉ及びＭｎは、脱酸剤として有効である他、耐高温酸化性を向上させる作用を有する。特に、耐高温酸化性を重視する場合には、Ｓｉについては０．０５質量％以上、Ｍｎについても０．０５質量％以上の含有量を確保することが効果的である。ただし、これらの元素を多量に含有させると鋼の脆化を招く要因となる。種々検討の結果、Ｓｉ及びＭｎともに２．００質量％以下の含有量に制限される。Ｓｉ及びＭｎの含有量はともに１．００質量％以下、又は０．５０質量％以下に管理してもよい。また、Ｓｉ及びＭｎの含有量の下限は、特に限定されないが、一般に０．０５質量％、好ましくは０．１質量％、より好ましくは０．１５質量％である。 <Si: 2.00% by mass or less, Mn: 2.00% by mass or less>
Si and Mn are effective as a deoxidizer and have an effect of improving high-temperature oxidation resistance. In particular, when emphasizing high-temperature oxidation resistance, it is effective to secure a content of 0.05% by mass or more for Si and 0.05% by mass or more for Mn. However, if these elements are contained in a large amount, it becomes a factor that causes embrittlement of the steel. As a result of various studies, both Si and Mn are limited to a content of 2.00% by mass or less. You may manage content of Si and Mn to 1.00 mass% or less, or 0.50 mass% or less. Moreover, although the minimum of content of Si and Mn is not specifically limited, Generally 0.05 mass%, Preferably it is 0.1 mass%, More preferably, it is 0.15 mass%.
Ｓｉ及びＭｎは、脱酸剤として有効である他、耐高温酸化性を向上させる作用を有する。特に、耐高温酸化性を重視する場合には、Ｓｉについては０．０５質量％以上、Ｍｎについても０．０５質量％以上の含有量を確保することが効果的である。ただし、これらの元素を多量に含有させると鋼の脆化を招く要因となる。種々検討の結果、Ｓｉ及びＭｎともに２．００質量％以下の含有量に制限される。Ｓｉ及びＭｎの含有量はともに１．００質量％以下、又は０．５０質量％以下に管理してもよい。また、Ｓｉ及びＭｎの含有量の下限は、特に限定されないが、一般に０．０５質量％、好ましくは０．１質量％、より好ましくは０．１５質量％である。 <Si: 2.00% by mass or less, Mn: 2.00% by mass or less>
Si and Mn are effective as a deoxidizer and have an effect of improving high-temperature oxidation resistance. In particular, when emphasizing high-temperature oxidation resistance, it is effective to secure a content of 0.05% by mass or more for Si and 0.05% by mass or more for Mn. However, if these elements are contained in a large amount, it becomes a factor that causes embrittlement of the steel. As a result of various studies, both Si and Mn are limited to a content of 2.00% by mass or less. You may manage content of Si and Mn to 1.00 mass% or less, or 0.50 mass% or less. Moreover, although the minimum of content of Si and Mn is not specifically limited, Generally 0.05 mass%, Preferably it is 0.1 mass%, More preferably, it is 0.15 mass%.
＜Ｐ：０．０５０質量％以下、Ｓ：０．０４０質量％以下＞
Ｐ及びＳは、多量に含有すると耐食性低下などの要因となり得る。そのため、Ｐの含有量は０．０５０質量％以下、Ｓの含有量は０．０４０質量％以下に制限される。通常、Ｐの含有量は０．０１０質量％～０．０５０質量％、Ｓの含有量は０．０００５質量％～０．０４０質量％の範囲とすればよい。また、Ｐの好ましい含有量は、０．０２０質量％～０．０４０質量％、Ｓの好ましい含有量は０．００１質量％～０．０１０質量％である。特に、耐食性を重視する場合はＳの含有量を０．００５質量％以下に制限することが効果的である。 <P: 0.050 mass% or less, S: 0.040 mass% or less>
When P and S are contained in a large amount, they may cause a decrease in corrosion resistance. Therefore, the P content is limited to 0.050 mass% or less, and the S content is limited to 0.040 mass% or less. Usually, the P content may be in the range of 0.010 mass% to 0.050 mass%, and the S content may be in the range of 0.0005 mass% to 0.040 mass%. The preferable content of P is 0.020 mass% to 0.040 mass%, and the preferable content of S is 0.001 mass% to 0.010 mass%. In particular, when emphasizing corrosion resistance, it is effective to limit the S content to 0.005% by mass or less.
Ｐ及びＳは、多量に含有すると耐食性低下などの要因となり得る。そのため、Ｐの含有量は０．０５０質量％以下、Ｓの含有量は０．０４０質量％以下に制限される。通常、Ｐの含有量は０．０１０質量％～０．０５０質量％、Ｓの含有量は０．０００５質量％～０．０４０質量％の範囲とすればよい。また、Ｐの好ましい含有量は、０．０２０質量％～０．０４０質量％、Ｓの好ましい含有量は０．００１質量％～０．０１０質量％である。特に、耐食性を重視する場合はＳの含有量を０．００５質量％以下に制限することが効果的である。 <P: 0.050 mass% or less, S: 0.040 mass% or less>
When P and S are contained in a large amount, they may cause a decrease in corrosion resistance. Therefore, the P content is limited to 0.050 mass% or less, and the S content is limited to 0.040 mass% or less. Usually, the P content may be in the range of 0.010 mass% to 0.050 mass%, and the S content may be in the range of 0.0005 mass% to 0.040 mass%. The preferable content of P is 0.020 mass% to 0.040 mass%, and the preferable content of S is 0.001 mass% to 0.010 mass%. In particular, when emphasizing corrosion resistance, it is effective to limit the S content to 0.005% by mass or less.
＜Ｃｒ：１０．００質量％～２５．００質量％＞
Ｃｒは、ステンレス鋼としての耐食性を確保するために重要な元素であると共に、耐高温酸化性の向上にも有効である。これらの作用を発揮させるためには１０．００質量％以上のＣｒ含有量が必要となる。Ｃｒの含有量は、好ましくは１３．５０質量％以上、より好ましくは１７．００質量％以上とすることが、上記の作用を発揮させる点で効果的である。一方、多量にＣｒを含有させると、鋼の硬質化及び靱性低下によって厚ゲージ熱延鋼板の製造性が難しくなる。種々検討の結果、Ｃｒの含有量は２５．００質量％以下、好ましくは２２．００質量％以下、より好ましくは２０．００質量％以下に制限される。 <Cr: 10.00 mass% to 25.00 mass%>
Cr is an important element for ensuring the corrosion resistance as stainless steel, and is also effective in improving high-temperature oxidation resistance. In order to exert these effects, a Cr content of 10.00% by mass or more is required. The content of Cr is preferably 13.50% by mass or more, more preferably 17.00% by mass or more from the viewpoint of exerting the above-described action. On the other hand, if a large amount of Cr is contained, the manufacturability of the thick gauge hot-rolled steel sheet becomes difficult due to the hardening of the steel and the reduction in toughness. As a result of various studies, the Cr content is limited to 25.00 mass% or less, preferably 22.00 mass% or less, more preferably 20.00 mass% or less.
Ｃｒは、ステンレス鋼としての耐食性を確保するために重要な元素であると共に、耐高温酸化性の向上にも有効である。これらの作用を発揮させるためには１０．００質量％以上のＣｒ含有量が必要となる。Ｃｒの含有量は、好ましくは１３．５０質量％以上、より好ましくは１７．００質量％以上とすることが、上記の作用を発揮させる点で効果的である。一方、多量にＣｒを含有させると、鋼の硬質化及び靱性低下によって厚ゲージ熱延鋼板の製造性が難しくなる。種々検討の結果、Ｃｒの含有量は２５．００質量％以下、好ましくは２２．００質量％以下、より好ましくは２０．００質量％以下に制限される。 <Cr: 10.00 mass% to 25.00 mass%>
Cr is an important element for ensuring the corrosion resistance as stainless steel, and is also effective in improving high-temperature oxidation resistance. In order to exert these effects, a Cr content of 10.00% by mass or more is required. The content of Cr is preferably 13.50% by mass or more, more preferably 17.00% by mass or more from the viewpoint of exerting the above-described action. On the other hand, if a large amount of Cr is contained, the manufacturability of the thick gauge hot-rolled steel sheet becomes difficult due to the hardening of the steel and the reduction in toughness. As a result of various studies, the Cr content is limited to 25.00 mass% or less, preferably 22.00 mass% or less, more preferably 20.00 mass% or less.
＜Ｎ：０．０３０質量％以下＞
Ｎは、靱性を低下させる要因となる。そのため、Ｎの含有量は０．０３０質量％以下に制限される。ただし、Ｎの含有量を極度に低下させる必要はなく、一般に０．００１質量％～０．０３０質量％、好ましくは０．００５質量％～０．０２５質量％のＮ含有量とすればよい。 <N: 0.030% by mass or less>
N becomes a factor which reduces toughness. Therefore, the N content is limited to 0.030% by mass or less. However, it is not necessary to extremely reduce the N content. Generally, the N content may be 0.001% by mass to 0.030% by mass, and preferably 0.005% by mass to 0.025% by mass.
Ｎは、靱性を低下させる要因となる。そのため、Ｎの含有量は０．０３０質量％以下に制限される。ただし、Ｎの含有量を極度に低下させる必要はなく、一般に０．００１質量％～０．０３０質量％、好ましくは０．００５質量％～０．０２５質量％のＮ含有量とすればよい。 <N: 0.030% by mass or less>
N becomes a factor which reduces toughness. Therefore, the N content is limited to 0.030% by mass or less. However, it is not necessary to extremely reduce the N content. Generally, the N content may be 0.001% by mass to 0.030% by mass, and preferably 0.005% by mass to 0.025% by mass.
＜Ｎｂ：０．０１質量％～０．８０質量％＞
Ｎｂは、Ｃ及びＮを固定することによってＣｒ炭窒化物（炭化物・窒化物）の粒界偏析を抑制し、鋼の耐食性及び耐高温酸化性を高く維持する上で極めて有効な元素である。そのため、Ｎｂの含有量は０．０１質量％以上とする必要がある。Ｎｂの含有量は０．０５質量％以上とすることが効果的であり、０．２０質量％以上とすることがより効果的である。ただし、Ｎｂの含有量が高すぎると、熱延鋼板の靱性低下を助長するので好ましくない。種々検討の結果、Ｎｂの含有量は０．８０質量％以下、好ましくは０．６０質量％以下に制限される。 <Nb: 0.01% by mass to 0.80% by mass>
Nb is an extremely effective element for fixing the C and N to suppress grain boundary segregation of Cr carbonitrides (carbides / nitrides) and to maintain high corrosion resistance and high temperature oxidation resistance of the steel. Therefore, the Nb content needs to be 0.01% by mass or more. The Nb content is effectively 0.05% by mass or more, and more preferably 0.20% by mass or more. However, if the content of Nb is too high, it is not preferable because it promotes toughness reduction of the hot-rolled steel sheet. As a result of various studies, the Nb content is limited to 0.80% by mass or less, preferably 0.60% by mass or less.
Ｎｂは、Ｃ及びＮを固定することによってＣｒ炭窒化物（炭化物・窒化物）の粒界偏析を抑制し、鋼の耐食性及び耐高温酸化性を高く維持する上で極めて有効な元素である。そのため、Ｎｂの含有量は０．０１質量％以上とする必要がある。Ｎｂの含有量は０．０５質量％以上とすることが効果的であり、０．２０質量％以上とすることがより効果的である。ただし、Ｎｂの含有量が高すぎると、熱延鋼板の靱性低下を助長するので好ましくない。種々検討の結果、Ｎｂの含有量は０．８０質量％以下、好ましくは０．６０質量％以下に制限される。 <Nb: 0.01% by mass to 0.80% by mass>
Nb is an extremely effective element for fixing the C and N to suppress grain boundary segregation of Cr carbonitrides (carbides / nitrides) and to maintain high corrosion resistance and high temperature oxidation resistance of the steel. Therefore, the Nb content needs to be 0.01% by mass or more. The Nb content is effectively 0.05% by mass or more, and more preferably 0.20% by mass or more. However, if the content of Nb is too high, it is not preferable because it promotes toughness reduction of the hot-rolled steel sheet. As a result of various studies, the Nb content is limited to 0.80% by mass or less, preferably 0.60% by mass or less.
＜Ｎｉ：２．００質量％以下＞
Ｎｉは、腐食の進行を抑制する作用があり、必要に応じて添加することができる。その場合、０．０１質量％以上のＮｉ含有量を確保することが効果的である。ただし、多量のＮｉを含有させると加工性に悪影響を及ぼすことがあるので、Ｎｉを添加する場合は２．００質量％以下、好ましくは１．００質量％以下の範囲で行う必要がある。 <Ni: 2.00% by mass or less>
Ni has an action of suppressing the progress of corrosion, and can be added as necessary. In that case, it is effective to secure a Ni content of 0.01% by mass or more. However, if a large amount of Ni is contained, workability may be adversely affected. Therefore, when Ni is added, it is necessary to carry out within a range of 2.00% by mass or less, preferably 1.00% by mass or less.
Ｎｉは、腐食の進行を抑制する作用があり、必要に応じて添加することができる。その場合、０．０１質量％以上のＮｉ含有量を確保することが効果的である。ただし、多量のＮｉを含有させると加工性に悪影響を及ぼすことがあるので、Ｎｉを添加する場合は２．００質量％以下、好ましくは１．００質量％以下の範囲で行う必要がある。 <Ni: 2.00% by mass or less>
Ni has an action of suppressing the progress of corrosion, and can be added as necessary. In that case, it is effective to secure a Ni content of 0.01% by mass or more. However, if a large amount of Ni is contained, workability may be adversely affected. Therefore, when Ni is added, it is necessary to carry out within a range of 2.00% by mass or less, preferably 1.00% by mass or less.
＜Ｍｏ：２．５０質量％以下＞
Ｍｏは、耐食性の向上に有効な元素であり、必要に応じて添加することができる。その場合、０．０２質量％以上のＭｏ含有量を確保することが効果的であり、０．５０質量％以上とすることがより効果的である。ただし、多量のＭｏを含有させると靱性に悪影響を及ぼすので、Ｍｏを添加する場合は２．５０質量％以下、好ましくは１．５０質量％以下の範囲で行う必要がある。 <Mo: 2.50 mass% or less>
Mo is an element effective for improving the corrosion resistance, and can be added as necessary. In that case, it is effective to secure a Mo content of 0.02 mass% or more, and it is more effective to set it to 0.50 mass% or more. However, if a large amount of Mo is contained, the toughness is adversely affected. Therefore, when Mo is added, it is necessary to be performed in a range of 2.50% by mass or less, preferably 1.50% by mass or less.
Ｍｏは、耐食性の向上に有効な元素であり、必要に応じて添加することができる。その場合、０．０２質量％以上のＭｏ含有量を確保することが効果的であり、０．５０質量％以上とすることがより効果的である。ただし、多量のＭｏを含有させると靱性に悪影響を及ぼすので、Ｍｏを添加する場合は２．５０質量％以下、好ましくは１．５０質量％以下の範囲で行う必要がある。 <Mo: 2.50 mass% or less>
Mo is an element effective for improving the corrosion resistance, and can be added as necessary. In that case, it is effective to secure a Mo content of 0.02 mass% or more, and it is more effective to set it to 0.50 mass% or more. However, if a large amount of Mo is contained, the toughness is adversely affected. Therefore, when Mo is added, it is necessary to be performed in a range of 2.50% by mass or less, preferably 1.50% by mass or less.
＜Ｃｕ：１．８０質量％以下＞
Ｃｕは、低温靱性の向上に有効であると共に、高温強度の向上にも有効な元素である。そのため、必要に応じてＣｕを添加することができる。その場合、０．０２質量％以上のＣｕ含有量を確保することが効果的である。ただし、多量にＣｕを添加すると加工性がむしろ低下するようになる。Ｃｕを添加する場合は１．８０質量％以下、好ましくは０．８０質量％以下の範囲で行う必要がある。 <Cu: 1.80% by mass or less>
Cu is an element effective not only for improving low-temperature toughness but also for improving high-temperature strength. Therefore, Cu can be added as needed. In that case, it is effective to secure a Cu content of 0.02 mass% or more. However, when a large amount of Cu is added, the workability is rather lowered. When adding Cu, it is necessary to carry out in 1.80 mass% or less, Preferably it is 0.80 mass% or less.
Ｃｕは、低温靱性の向上に有効であると共に、高温強度の向上にも有効な元素である。そのため、必要に応じてＣｕを添加することができる。その場合、０．０２質量％以上のＣｕ含有量を確保することが効果的である。ただし、多量にＣｕを添加すると加工性がむしろ低下するようになる。Ｃｕを添加する場合は１．８０質量％以下、好ましくは０．８０質量％以下の範囲で行う必要がある。 <Cu: 1.80% by mass or less>
Cu is an element effective not only for improving low-temperature toughness but also for improving high-temperature strength. Therefore, Cu can be added as needed. In that case, it is effective to secure a Cu content of 0.02 mass% or more. However, when a large amount of Cu is added, the workability is rather lowered. When adding Cu, it is necessary to carry out in 1.80 mass% or less, Preferably it is 0.80 mass% or less.
＜Ｃｏ：０．５０質量％以下＞
Ｃｏは、低温靭性に寄与する元素であり、必要に応じて添加することができる。その場合、０．０１０質量％以上のＣｏ含有量を確保することが効果的である。ただし、Ｃｏの過剰添加は延性低下の要因となるので、Ｃｏを添加する場合は０．５０質量％以下の範囲で行う必要がある。 <Co: 0.50 mass% or less>
Co is an element contributing to low temperature toughness, and can be added as necessary. In that case, it is effective to secure a Co content of 0.010% by mass or more. However, since excessive addition of Co causes a decrease in ductility, it is necessary to add Co in a range of 0.50% by mass or less.
Ｃｏは、低温靭性に寄与する元素であり、必要に応じて添加することができる。その場合、０．０１０質量％以上のＣｏ含有量を確保することが効果的である。ただし、Ｃｏの過剰添加は延性低下の要因となるので、Ｃｏを添加する場合は０．５０質量％以下の範囲で行う必要がある。 <Co: 0.50 mass% or less>
Co is an element contributing to low temperature toughness, and can be added as necessary. In that case, it is effective to secure a Co content of 0.010% by mass or more. However, since excessive addition of Co causes a decrease in ductility, it is necessary to add Co in a range of 0.50% by mass or less.
＜Ａｌ：０．５０質量％以下＞
Ａｌは、脱酸剤として有効な元素であり、必要に応じて添加することができる。その場合、０．００５質量％以上のＡｌ含有量とすることが効果的である。ただし、多量のＡｌを含有させると靱性低下の要因となる。そのため、Ａｌを含有させる場合、Ａｌ含有量は０．５０質量％以下、好ましくは０．２０質量％以下に制限される。 <Al: 0.50 mass% or less>
Al is an element effective as a deoxidizer, and can be added as necessary. In that case, it is effective to make Al content 0.005 mass% or more. However, if a large amount of Al is contained, it causes a decrease in toughness. Therefore, when Al is contained, the Al content is limited to 0.50% by mass or less, preferably 0.20% by mass or less.
Ａｌは、脱酸剤として有効な元素であり、必要に応じて添加することができる。その場合、０．００５質量％以上のＡｌ含有量とすることが効果的である。ただし、多量のＡｌを含有させると靱性低下の要因となる。そのため、Ａｌを含有させる場合、Ａｌ含有量は０．５０質量％以下、好ましくは０．２０質量％以下に制限される。 <Al: 0.50 mass% or less>
Al is an element effective as a deoxidizer, and can be added as necessary. In that case, it is effective to make Al content 0.005 mass% or more. However, if a large amount of Al is contained, it causes a decrease in toughness. Therefore, when Al is contained, the Al content is limited to 0.50% by mass or less, preferably 0.20% by mass or less.
＜Ｗ：１．８０質量％以下、Ｖ：０．３０質量％以下＞
Ｗ及びＶは、高温強度の向上に有効な元素であり、必要に応じてこれらの１種以上を添加することができる。その場合、Ｗについては０．１０質量％以上、Ｖについても０．１０質量％以上の含有量を確保することが効果的である。ただし、これらの元素を多量に添加すると鋼が硬質となり、冷延時に割れを招く要因となる。Ｗを添加する場合は１．８０質量％以下、好ましくは０．５０質量％以下の範囲で行う必要がある。Ｖを添加する場合は０．３０質量％以下、好ましくは０．１５質量％以下の範囲で行う必要がある。 <W: 1.80 mass% or less, V: 0.30 mass% or less>
W and V are effective elements for improving the high-temperature strength, and one or more of them can be added as necessary. In that case, it is effective to secure a content of 0.10% by mass or more for W and 0.10% by mass or more for V. However, if these elements are added in a large amount, the steel becomes hard and causes cracking during cold rolling. When adding W, it is necessary to carry out in 1.80 mass% or less, Preferably it is 0.50 mass% or less. When adding V, it is necessary to carry out in the range of 0.30 mass% or less, preferably 0.15 mass% or less.
Ｗ及びＶは、高温強度の向上に有効な元素であり、必要に応じてこれらの１種以上を添加することができる。その場合、Ｗについては０．１０質量％以上、Ｖについても０．１０質量％以上の含有量を確保することが効果的である。ただし、これらの元素を多量に添加すると鋼が硬質となり、冷延時に割れを招く要因となる。Ｗを添加する場合は１．８０質量％以下、好ましくは０．５０質量％以下の範囲で行う必要がある。Ｖを添加する場合は０．３０質量％以下、好ましくは０．１５質量％以下の範囲で行う必要がある。 <W: 1.80 mass% or less, V: 0.30 mass% or less>
W and V are effective elements for improving the high-temperature strength, and one or more of them can be added as necessary. In that case, it is effective to secure a content of 0.10% by mass or more for W and 0.10% by mass or more for V. However, if these elements are added in a large amount, the steel becomes hard and causes cracking during cold rolling. When adding W, it is necessary to carry out in 1.80 mass% or less, Preferably it is 0.50 mass% or less. When adding V, it is necessary to carry out in the range of 0.30 mass% or less, preferably 0.15 mass% or less.
＜Ｔｉ：０．５０質量％以下、Ｚｒ：０．２０質量％以下＞
Ｔｉ及びＺｒは、Ｃ及びＮを固定する作用があり、鋼の耐食性及び耐高温酸化性を高く維持する上で有効な元素である。そのため、必要に応じてＴｉ、Ｚｒの１種以上を添加することができる。その場合、Ｔｉについては０．０１質量％以上、Ｚｒについては０．０２質量％以上の含有量を確保することが効果的である。ただし、過剰のＴｉを含有させると熱延コイルの靱性低下を助長するので、Ｔｉを添加する場合は０．５０質量％以下の範囲で行う必要がある。また、多量のＺｒを含有させると加工性を阻害する要因となるので、Ｚｒを添加する場合は０．２０質量％以下の範囲で行う必要がある。 <Ti: 0.50 mass% or less, Zr: 0.20 mass% or less>
Ti and Zr have an action of fixing C and N, and are effective elements for maintaining high corrosion resistance and high temperature oxidation resistance of steel. Therefore, one or more of Ti and Zr can be added as necessary. In that case, it is effective to secure a content of 0.01% by mass or more for Ti and 0.02% by mass or more for Zr. However, if excessive Ti is contained, the reduction in toughness of the hot-rolled coil is promoted. Therefore, when Ti is added, it is necessary to carry out within a range of 0.50 mass% or less. Further, when a large amount of Zr is contained, it becomes a factor that hinders workability. Therefore, when adding Zr, it is necessary to carry out within a range of 0.20 mass% or less.
Ｔｉ及びＺｒは、Ｃ及びＮを固定する作用があり、鋼の耐食性及び耐高温酸化性を高く維持する上で有効な元素である。そのため、必要に応じてＴｉ、Ｚｒの１種以上を添加することができる。その場合、Ｔｉについては０．０１質量％以上、Ｚｒについては０．０２質量％以上の含有量を確保することが効果的である。ただし、過剰のＴｉを含有させると熱延コイルの靱性低下を助長するので、Ｔｉを添加する場合は０．５０質量％以下の範囲で行う必要がある。また、多量のＺｒを含有させると加工性を阻害する要因となるので、Ｚｒを添加する場合は０．２０質量％以下の範囲で行う必要がある。 <Ti: 0.50 mass% or less, Zr: 0.20 mass% or less>
Ti and Zr have an action of fixing C and N, and are effective elements for maintaining high corrosion resistance and high temperature oxidation resistance of steel. Therefore, one or more of Ti and Zr can be added as necessary. In that case, it is effective to secure a content of 0.01% by mass or more for Ti and 0.02% by mass or more for Zr. However, if excessive Ti is contained, the reduction in toughness of the hot-rolled coil is promoted. Therefore, when Ti is added, it is necessary to carry out within a range of 0.50 mass% or less. Further, when a large amount of Zr is contained, it becomes a factor that hinders workability. Therefore, when adding Zr, it is necessary to carry out within a range of 0.20 mass% or less.
＜Ｂ：０．００５０質量％以下＞
Ｂは、少量の添加によって耐食性及び加工性を改善する元素であり、必要に応じてこれらの１種以上を添加することができる。その場合、０．０００１質量％以上のＢ含有量を確保することが効果的である。ただし、過剰のＢを含有させると熱間加工性に悪影響を及ぼすので、Ｂを添加する場合は０．００５０質量％以下の範囲で行う必要がある。 <B: 0.0050 mass% or less>
B is an element that improves corrosion resistance and workability by addition of a small amount, and one or more of these can be added as necessary. In that case, it is effective to secure a B content of 0.0001% by mass or more. However, if excessive B is contained, the hot workability is adversely affected. Therefore, when B is added, it is necessary to carry out within a range of 0.0050 mass% or less.
Ｂは、少量の添加によって耐食性及び加工性を改善する元素であり、必要に応じてこれらの１種以上を添加することができる。その場合、０．０００１質量％以上のＢ含有量を確保することが効果的である。ただし、過剰のＢを含有させると熱間加工性に悪影響を及ぼすので、Ｂを添加する場合は０．００５０質量％以下の範囲で行う必要がある。 <B: 0.0050 mass% or less>
B is an element that improves corrosion resistance and workability by addition of a small amount, and one or more of these can be added as necessary. In that case, it is effective to secure a B content of 0.0001% by mass or more. However, if excessive B is contained, the hot workability is adversely affected. Therefore, when B is added, it is necessary to carry out within a range of 0.0050 mass% or less.
＜希土類元素：０．１００質量％以下、Ｃａ：０．００５０質量％以下＞
希土類元素及びＣａは、耐高温酸化性の向上に有効な元素であり、必要に応じてこれらの１種以上を添加することができる。その場合、希土類元素は０．００１質量％以上、Ｃａは０．０００５質量％以上の含有量を確保することが効果的である。ただし、これらの元素を多量に添加すると靱性が低下するので、希土類元素を添加する場合は０．１００質量％以下、Ｃａを添加する場合は０．００５０質量％以下の含有量の範囲で行う必要がある。 <Rare earth element: 0.100 mass% or less, Ca: 0.0050 mass% or less>
Rare earth elements and Ca are effective elements for improving high-temperature oxidation resistance, and one or more of them can be added as necessary. In that case, it is effective to secure a content of 0.001% by mass or more for rare earth elements and 0.0005% by mass or more for Ca. However, since the toughness decreases when a large amount of these elements are added, it is necessary to perform the addition within a range of contents of 0.100% by mass or less when adding rare earth elements and 0.0050% by mass or less when adding Ca. There is.
希土類元素及びＣａは、耐高温酸化性の向上に有効な元素であり、必要に応じてこれらの１種以上を添加することができる。その場合、希土類元素は０．００１質量％以上、Ｃａは０．０００５質量％以上の含有量を確保することが効果的である。ただし、これらの元素を多量に添加すると靱性が低下するので、希土類元素を添加する場合は０．１００質量％以下、Ｃａを添加する場合は０．００５０質量％以下の含有量の範囲で行う必要がある。 <Rare earth element: 0.100 mass% or less, Ca: 0.0050 mass% or less>
Rare earth elements and Ca are effective elements for improving high-temperature oxidation resistance, and one or more of them can be added as necessary. In that case, it is effective to secure a content of 0.001% by mass or more for rare earth elements and 0.0005% by mass or more for Ca. However, since the toughness decreases when a large amount of these elements are added, it is necessary to perform the addition within a range of contents of 0.100% by mass or less when adding rare earth elements and 0.0050% by mass or less when adding Ca. There is.
＜残部：Ｆｅ及び不可避的不純物＞
上記以外の成分である残部は、Ｆｅ及び不可避的不純物からなる。ここで、不可避的不純物とは、製造工程中に材料中への混入が避けられない不純物元素のことを意味する。不可避的不純物としては、特に限定されない。 <Balance: Fe and inevitable impurities>
The balance which is a component other than the above consists of Fe and inevitable impurities. Here, the inevitable impurities mean impurity elements that cannot be mixed into the material during the manufacturing process. Inevitable impurities are not particularly limited.
上記以外の成分である残部は、Ｆｅ及び不可避的不純物からなる。ここで、不可避的不純物とは、製造工程中に材料中への混入が避けられない不純物元素のことを意味する。不可避的不純物としては、特に限定されない。 <Balance: Fe and inevitable impurities>
The balance which is a component other than the above consists of Fe and inevitable impurities. Here, the inevitable impurities mean impurity elements that cannot be mixed into the material during the manufacturing process. Inevitable impurities are not particularly limited.
＜Ｎｂ炭窒化物の析出量が０．２質量％以上、粒径０．１μｍ以下のラーベス相が面積１０μｍ2あたり１０個以下＞
Ｎｂ炭窒化物（炭化物・窒化物）及びラーベス相は、熱延処理によって生成する析出物である。Ｃ及びＮが鋼中に固溶した状態で存在すると、熱延鋼板の靭性が低下するため、Ｃ及びＮはＮｂ炭窒化物として析出させることが有効である。また、Ｎｂ炭窒化物を析出させることにより、鋼中に固溶しているＮｂが低減され、熱延鋼板の靭性を低下させるラーベス相の析出量を低減させることができる。鋼中に固溶するＣ及びＮを低減して熱延鋼板の靱性を向上させるためには、Ｎｂ炭窒化物の析出量を０．２質量％以上にする必要がある。また、粒径０．１μｍ以下のラーベス相を面積１０μｍ2あたり１０個以下にする必要がある。
ここで、Ｎｂ炭窒化物の析出量（質量％）は、１０質量％のアセチルアセトン＋１質量％のテトラメチルアンモニウムクロライド＋８９質量％のメチルアルコールの混合液を用い、飽和甘汞基準電極に対して－１００ｍＶ～４００ｍＶのＳＣＥ電位で析出物の残渣を電解抽出した後、抽出した残渣を０．２μｍのミクロポアフィルターにて濾過し、その重量と全溶解重量との比から算出した。
また、ラーベス相については、走査型電子顕微鏡（ＳＥＭ）を用いて表面の写真を撮影し、ラーベス相のサイズを測定すると共に、面積１０μｍ2あたりの粒径０．１μｍ以下のラーベス相の個数を計測した。ラーベス相の個数は、少なくとも５つのポイントで計測し、その平均値をとった。 <No more than 10 Laves phases with an Nb carbonitride content of 0.2% by mass or more and a particle size of 0.1 μm or less per 10 μm 2 area>
Nb carbonitride (carbide / nitride) and Laves phase are precipitates generated by hot rolling. If C and N are present in a solid solution state in the steel, the toughness of the hot-rolled steel sheet is lowered, so it is effective to precipitate C and N as Nb carbonitride. In addition, by precipitating Nb carbonitride, Nb dissolved in the steel is reduced, and the amount of Laves phase precipitation that lowers the toughness of the hot-rolled steel sheet can be reduced. In order to reduce the C and N dissolved in the steel and improve the toughness of the hot-rolled steel sheet, the amount of precipitation of Nb carbonitride needs to be 0.2% by mass or more. Further, it is necessary to make 10 or less Laves phases having a particle size of 0.1 μm or less per 10 μm 2 area.
Here, the precipitation amount (% by mass) of Nb carbonitride is 10% by mass of acetylacetone + 1% by mass of tetramethylammonium chloride + 89% by mass of methyl alcohol, and is − The residue of the precipitate was subjected to electrolytic extraction at an SCE potential of 100 mV to 400 mV, and then the extracted residue was filtered through a 0.2 μm micropore filter, and calculated from the ratio of the weight to the total dissolved weight.
As for the Laves phase, a surface photograph was taken using a scanning electron microscope (SEM), the size of the Laves phase was measured, and the number of Laves phases having a particle size of 0.1 μm or less per 10 μm 2 area was determined. Measured. The number of Laves phases was measured at at least 5 points and the average value was taken.
Ｎｂ炭窒化物（炭化物・窒化物）及びラーベス相は、熱延処理によって生成する析出物である。Ｃ及びＮが鋼中に固溶した状態で存在すると、熱延鋼板の靭性が低下するため、Ｃ及びＮはＮｂ炭窒化物として析出させることが有効である。また、Ｎｂ炭窒化物を析出させることにより、鋼中に固溶しているＮｂが低減され、熱延鋼板の靭性を低下させるラーベス相の析出量を低減させることができる。鋼中に固溶するＣ及びＮを低減して熱延鋼板の靱性を向上させるためには、Ｎｂ炭窒化物の析出量を０．２質量％以上にする必要がある。また、粒径０．１μｍ以下のラーベス相を面積１０μｍ2あたり１０個以下にする必要がある。
ここで、Ｎｂ炭窒化物の析出量（質量％）は、１０質量％のアセチルアセトン＋１質量％のテトラメチルアンモニウムクロライド＋８９質量％のメチルアルコールの混合液を用い、飽和甘汞基準電極に対して－１００ｍＶ～４００ｍＶのＳＣＥ電位で析出物の残渣を電解抽出した後、抽出した残渣を０．２μｍのミクロポアフィルターにて濾過し、その重量と全溶解重量との比から算出した。
また、ラーベス相については、走査型電子顕微鏡（ＳＥＭ）を用いて表面の写真を撮影し、ラーベス相のサイズを測定すると共に、面積１０μｍ2あたりの粒径０．１μｍ以下のラーベス相の個数を計測した。ラーベス相の個数は、少なくとも５つのポイントで計測し、その平均値をとった。 <No more than 10 Laves phases with an Nb carbonitride content of 0.2% by mass or more and a particle size of 0.1 μm or less per 10 μm 2 area>
Nb carbonitride (carbide / nitride) and Laves phase are precipitates generated by hot rolling. If C and N are present in a solid solution state in the steel, the toughness of the hot-rolled steel sheet is lowered, so it is effective to precipitate C and N as Nb carbonitride. In addition, by precipitating Nb carbonitride, Nb dissolved in the steel is reduced, and the amount of Laves phase precipitation that lowers the toughness of the hot-rolled steel sheet can be reduced. In order to reduce the C and N dissolved in the steel and improve the toughness of the hot-rolled steel sheet, the amount of precipitation of Nb carbonitride needs to be 0.2% by mass or more. Further, it is necessary to make 10 or less Laves phases having a particle size of 0.1 μm or less per 10 μm 2 area.
Here, the precipitation amount (% by mass) of Nb carbonitride is 10% by mass of acetylacetone + 1% by mass of tetramethylammonium chloride + 89% by mass of methyl alcohol, and is − The residue of the precipitate was subjected to electrolytic extraction at an SCE potential of 100 mV to 400 mV, and then the extracted residue was filtered through a 0.2 μm micropore filter, and calculated from the ratio of the weight to the total dissolved weight.
As for the Laves phase, a surface photograph was taken using a scanning electron microscope (SEM), the size of the Laves phase was measured, and the number of Laves phases having a particle size of 0.1 μm or less per 10 μm 2 area was determined. Measured. The number of Laves phases was measured at at least 5 points and the average value was taken.
＜厚さ＞
本発明の熱延鋼板の厚さは、用途に応じて適宜設定すればよく特に限定されない。例えば、本発明の熱延鋼板を自動車の排気管フランジ部品の製造に用いる場合、熱延鋼板の厚さは、一般に５．０ｍｍ～１１．０ｍｍ、好ましくは５．５ｍｍ～９．０ｍｍである。また、本発明の熱延鋼板を自動車の排気管部品の製造に用いる場合、Ｎｂ含有フェライト系ステンレス冷延鋼板（以下、「冷延鋼板」と略すことがある。）の加工性の指標であるｒ値を向上させるために、本発明の熱延鋼板を冷延する際に圧下率を大きくする必要がある。したがって、自動車の排気管部品を製造するために用いられる冷延鋼板の厚さ及び冷延圧下率を考慮すると、熱延鋼板の厚さは、通常、４．５ｍｍ超過１０．００ｍｍ以下である。また、熱延鋼板の厚さは、好ましくは５．０ｍｍ～９．０ｍｍ、より好ましくは５．５ｍｍ～８．０ｍｍである。 <Thickness>
The thickness of the hot-rolled steel sheet of the present invention is not particularly limited as long as it is appropriately set depending on the application. For example, when the hot-rolled steel sheet of the present invention is used for manufacturing an exhaust pipe flange part of an automobile, the thickness of the hot-rolled steel sheet is generally 5.0 mm to 11.0 mm, preferably 5.5 mm to 9.0 mm. Further, when the hot-rolled steel sheet of the present invention is used for the production of automobile exhaust pipe parts, it is an index of workability of Nb-containing ferritic stainless steel cold-rolled steel sheets (hereinafter sometimes abbreviated as “cold-rolled steel sheets”). In order to improve the r value, it is necessary to increase the rolling reduction when the hot-rolled steel sheet of the present invention is cold-rolled. Therefore, considering the thickness of the cold-rolled steel sheet used for manufacturing the exhaust pipe part of the automobile and the cold rolling reduction ratio, the thickness of the hot-rolled steel sheet is usually more than 4.5 mm and not more than 10.00 mm. The thickness of the hot-rolled steel sheet is preferably 5.0 mm to 9.0 mm, more preferably 5.5 mm to 8.0 mm.
本発明の熱延鋼板の厚さは、用途に応じて適宜設定すればよく特に限定されない。例えば、本発明の熱延鋼板を自動車の排気管フランジ部品の製造に用いる場合、熱延鋼板の厚さは、一般に５．０ｍｍ～１１．０ｍｍ、好ましくは５．５ｍｍ～９．０ｍｍである。また、本発明の熱延鋼板を自動車の排気管部品の製造に用いる場合、Ｎｂ含有フェライト系ステンレス冷延鋼板（以下、「冷延鋼板」と略すことがある。）の加工性の指標であるｒ値を向上させるために、本発明の熱延鋼板を冷延する際に圧下率を大きくする必要がある。したがって、自動車の排気管部品を製造するために用いられる冷延鋼板の厚さ及び冷延圧下率を考慮すると、熱延鋼板の厚さは、通常、４．５ｍｍ超過１０．００ｍｍ以下である。また、熱延鋼板の厚さは、好ましくは５．０ｍｍ～９．０ｍｍ、より好ましくは５．５ｍｍ～８．０ｍｍである。 <Thickness>
The thickness of the hot-rolled steel sheet of the present invention is not particularly limited as long as it is appropriately set depending on the application. For example, when the hot-rolled steel sheet of the present invention is used for manufacturing an exhaust pipe flange part of an automobile, the thickness of the hot-rolled steel sheet is generally 5.0 mm to 11.0 mm, preferably 5.5 mm to 9.0 mm. Further, when the hot-rolled steel sheet of the present invention is used for the production of automobile exhaust pipe parts, it is an index of workability of Nb-containing ferritic stainless steel cold-rolled steel sheets (hereinafter sometimes abbreviated as “cold-rolled steel sheets”). In order to improve the r value, it is necessary to increase the rolling reduction when the hot-rolled steel sheet of the present invention is cold-rolled. Therefore, considering the thickness of the cold-rolled steel sheet used for manufacturing the exhaust pipe part of the automobile and the cold rolling reduction ratio, the thickness of the hot-rolled steel sheet is usually more than 4.5 mm and not more than 10.00 mm. The thickness of the hot-rolled steel sheet is preferably 5.0 mm to 9.0 mm, more preferably 5.5 mm to 8.0 mm.
＜Ｎｂ含有フェライト系ステンレス熱延鋼板の製造方法＞
上記のような特徴を有する本発明のＮｂ含有フェライト系ステンレス熱延鋼板は、上記のＮｂ含有フェライト系ステンレス熱延鋼板と同じ組成を有するステンレス鋼スラブを熱延する際に、１０００℃～１１００℃の温度で６０秒以上保持すると共に仕上熱延温度を８５０℃以上とし、熱延後に５５０℃以下の巻取温度で巻取ることによって製造することができる。 <Method for producing Nb-containing ferritic stainless steel hot-rolled steel sheet>
The Nb-containing ferritic stainless steel hot-rolled steel sheet of the present invention having the above-described characteristics is 1000 ° C. to 1100 ° C. when hot rolling a stainless steel slab having the same composition as the Nb-containing ferritic stainless steel hot-rolled steel sheet. At the temperature of 60 seconds or more, and the finish hot rolling temperature is set to 850 ° C. or higher, and after the hot rolling, winding is performed at a winding temperature of 550 ° C. or lower.
上記のような特徴を有する本発明のＮｂ含有フェライト系ステンレス熱延鋼板は、上記のＮｂ含有フェライト系ステンレス熱延鋼板と同じ組成を有するステンレス鋼スラブを熱延する際に、１０００℃～１１００℃の温度で６０秒以上保持すると共に仕上熱延温度を８５０℃以上とし、熱延後に５５０℃以下の巻取温度で巻取ることによって製造することができる。 <Method for producing Nb-containing ferritic stainless steel hot-rolled steel sheet>
The Nb-containing ferritic stainless steel hot-rolled steel sheet of the present invention having the above-described characteristics is 1000 ° C. to 1100 ° C. when hot rolling a stainless steel slab having the same composition as the Nb-containing ferritic stainless steel hot-rolled steel sheet. At the temperature of 60 seconds or more, and the finish hot rolling temperature is set to 850 ° C. or higher, and after the hot rolling, winding is performed at a winding temperature of 550 ° C. or lower.
熱延に先立ち、通常、ステンレス鋼スラブは加熱される。ステンレス鋼スラブの加熱温度は、特に限定されないが、好ましくは１２００℃～１３００℃である。ステンレス鋼スラブの加熱温度が１２００℃未満であると、熱延による歪が過度に導入され、その後の組織制御が困難となる他、表面傷が問題となることがある。一方、ステンレス鋼スラブの加熱温度が１３００℃を超えると、組織が粗粒化してしまい、所望の特性を有する熱延鋼板が得られないことがある。
Prior to hot rolling, the stainless steel slab is usually heated. The heating temperature of the stainless steel slab is not particularly limited, but is preferably 1200 ° C to 1300 ° C. When the heating temperature of the stainless steel slab is less than 1200 ° C., distortion due to hot rolling is excessively introduced, and subsequent structure control becomes difficult, and surface scratches may become a problem. On the other hand, when the heating temperature of the stainless steel slab exceeds 1300 ° C., the structure becomes coarse and a hot-rolled steel sheet having desired characteristics may not be obtained.
上記のようにしてステンレス鋼スラブを加熱した後、熱延が行われる。熱延は、通常、複数パスの粗熱延、及び複数パスの仕上熱延を含む。熱延の際、Ｎｂ炭窒化物の析出を効率的に促進しつつラーベス相の析出を低減するため、１０００℃～１１００℃の温度で６０秒以上保持すると共に、仕上熱延温度を８５０℃以上とする必要がある。ここで、保持温度を１０００℃～１１００℃とする理由は、Ｎｂ炭窒化物の析出温度が１１００℃以下であり、特に当該保持温度とすることによってＮｂ炭窒化物の析出を効率良く促進させることができるためである。保持時間及び保持時間が上記範囲外であると、Ｎｂ炭窒化物が十分に析出しない。また、仕上熱延温度が８５０℃未満であると、ラーベス相の析出温度が８００℃付近であるため、ラーベス相の析出を十分に低減することができない。
After the stainless steel slab is heated as described above, hot rolling is performed. Hot rolling typically includes multiple passes of coarse hot rolling and multiple passes of finish hot rolling. During hot rolling, in order to reduce the deposition of Laves phase while efficiently promoting the precipitation of Nb carbonitride, the temperature is maintained at 1000 ° C. to 1100 ° C. for 60 seconds or more, and the finish hot rolling temperature is 850 ° C. or more. It is necessary to. Here, the reason why the holding temperature is set to 1000 ° C. to 1100 ° C. is that the precipitation temperature of Nb carbonitride is 1100 ° C. or less, and in particular, the precipitation of Nb carbonitride is efficiently promoted by setting the holding temperature. It is because it can do. When the holding time and the holding time are outside the above ranges, Nb carbonitride is not sufficiently precipitated. Further, when the finish hot rolling temperature is less than 850 ° C., the Laves phase precipitation temperature is around 800 ° C., and thus Laves phase precipitation cannot be sufficiently reduced.
１０００℃～１１００℃の温度で６０秒以上保持する方法としては、特に限定されず、通板速度を低下させたり、仕上圧延前にディレイを導入したりすればよい。
また、１０００℃～１１００℃の温度で６０秒以上保持するタイミングは、熱延工程の間であれば特に限定されないが、粗熱延の終期から仕上熱延の初期にかけて行うことが好ましい。
仕上熱延時間は、特に限定されず、当該技術分野において公知の熱延方法に準じて設定することができる。一般に、仕上熱延時間は、熱延工程のトータル時間との兼ね合いを考慮して決定されるが、仕上熱延時間が長いほどＮｂ炭窒化物の析出量が増大する。 The method of holding at a temperature of 1000 ° C. to 1100 ° C. for 60 seconds or more is not particularly limited, and it is sufficient to reduce the sheet passing speed or introduce a delay before finish rolling.
The timing of holding at a temperature of 1000 ° C. to 1100 ° C. for 60 seconds or more is not particularly limited as long as it is during the hot rolling process, but it is preferably performed from the end of rough hot rolling to the initial stage of finish hot rolling.
The finishing hot rolling time is not particularly limited, and can be set according to a hot rolling method known in the technical field. Generally, the finish hot rolling time is determined in consideration of the balance with the total time of the hot rolling process, but as the finish hot rolling time is longer, the amount of precipitation of Nb carbonitride increases.
また、１０００℃～１１００℃の温度で６０秒以上保持するタイミングは、熱延工程の間であれば特に限定されないが、粗熱延の終期から仕上熱延の初期にかけて行うことが好ましい。
仕上熱延時間は、特に限定されず、当該技術分野において公知の熱延方法に準じて設定することができる。一般に、仕上熱延時間は、熱延工程のトータル時間との兼ね合いを考慮して決定されるが、仕上熱延時間が長いほどＮｂ炭窒化物の析出量が増大する。 The method of holding at a temperature of 1000 ° C. to 1100 ° C. for 60 seconds or more is not particularly limited, and it is sufficient to reduce the sheet passing speed or introduce a delay before finish rolling.
The timing of holding at a temperature of 1000 ° C. to 1100 ° C. for 60 seconds or more is not particularly limited as long as it is during the hot rolling process, but it is preferably performed from the end of rough hot rolling to the initial stage of finish hot rolling.
The finishing hot rolling time is not particularly limited, and can be set according to a hot rolling method known in the technical field. Generally, the finish hot rolling time is determined in consideration of the balance with the total time of the hot rolling process, but as the finish hot rolling time is longer, the amount of precipitation of Nb carbonitride increases.
熱延後、５５０℃以下の巻取温度で巻取ってコイルとする。巻取温度が５５０℃を超えると、ラーベス相が析出し、靭性が低下してしまうことがある。
また、上記のようにして得られた熱延鋼板は、熱延工程においてＮｂ炭窒化物の析出量を十分に増大させているため、ラーベス相の析出温度（８００℃付近）となってもラーベス相が析出し難い。そのため、熱延鋼板を巻取る前に水冷などによって急冷し、ラーベス相の析出温度の通過時間を短くする手法を用いる必要性は少ない。 After hot rolling, the coil is wound at a winding temperature of 550 ° C. or lower. When the coiling temperature exceeds 550 ° C., a Laves phase may precipitate and the toughness may be lowered.
Moreover, since the hot-rolled steel sheet obtained as described above has sufficiently increased the precipitation amount of Nb carbonitride in the hot-rolling step, Laves can be obtained even when the precipitation temperature of Laves phase (around 800 ° C.) is reached. The phase is difficult to precipitate. For this reason, there is little need to use a technique in which the hot-rolled steel sheet is rapidly cooled by water cooling or the like to shorten the transit time of the Laves phase precipitation temperature.
また、上記のようにして得られた熱延鋼板は、熱延工程においてＮｂ炭窒化物の析出量を十分に増大させているため、ラーベス相の析出温度（８００℃付近）となってもラーベス相が析出し難い。そのため、熱延鋼板を巻取る前に水冷などによって急冷し、ラーベス相の析出温度の通過時間を短くする手法を用いる必要性は少ない。 After hot rolling, the coil is wound at a winding temperature of 550 ° C. or lower. When the coiling temperature exceeds 550 ° C., a Laves phase may precipitate and the toughness may be lowered.
Moreover, since the hot-rolled steel sheet obtained as described above has sufficiently increased the precipitation amount of Nb carbonitride in the hot-rolling step, Laves can be obtained even when the precipitation temperature of Laves phase (around 800 ° C.) is reached. The phase is difficult to precipitate. For this reason, there is little need to use a technique in which the hot-rolled steel sheet is rapidly cooled by water cooling or the like to shorten the transit time of the Laves phase precipitation temperature.
＜Ｎｂ含有フェライト系ステンレス冷延鋼板及びその製造方法＞
本発明の冷延鋼板は、上記の熱延鋼板の特徴に加えて、ｒ値が１．２以上であるという特徴を有する。そのため、本発明の冷延鋼板は加工性に優れており、種々の加工を行うことにより、エキゾーストマニホールド、フロントパイプ、センターパイプ、触媒コンバータ外筒などの自動車の排気管部品を製造することができる。
上記のような特徴を有する本発明の冷延鋼板は、上記の熱延鋼板を焼鈍した後、７０％以上の圧下率で冷延して焼鈍することによって製造することができる。
冷延に先立ち、熱延鋼板の焼鈍が行われる。焼鈍は、再結晶組織が得られる温度で行われる。焼鈍温度は、熱延鋼板の組成に応じて適宜設定すればよく、特に限定されないが、通常９５０℃～１１５０℃である。焼鈍温度が９５０℃未満であると、再結晶組織が得られないことがある。一方、焼鈍温度が１１５０℃を超えると、結晶粒が粗大化することがある。 <Nb-containing ferritic stainless steel cold rolled steel sheet and method for producing the same>
The cold-rolled steel sheet of the present invention has a feature that the r value is 1.2 or more in addition to the characteristics of the hot-rolled steel sheet. Therefore, the cold-rolled steel sheet of the present invention is excellent in workability, and by performing various processes, it is possible to manufacture automobile exhaust pipe parts such as an exhaust manifold, a front pipe, a center pipe, and a catalytic converter outer cylinder.
The cold-rolled steel sheet of the present invention having the above-described characteristics can be manufactured by annealing the hot-rolled steel sheet and then cold-rolling and annealing at a rolling reduction of 70% or more.
Prior to cold rolling, the hot rolled steel sheet is annealed. Annealing is performed at a temperature at which a recrystallized structure is obtained. The annealing temperature may be appropriately set according to the composition of the hot-rolled steel sheet and is not particularly limited, but is usually 950 ° C. to 1150 ° C. When the annealing temperature is less than 950 ° C., a recrystallized structure may not be obtained. On the other hand, when the annealing temperature exceeds 1150 ° C., the crystal grains may become coarse.
本発明の冷延鋼板は、上記の熱延鋼板の特徴に加えて、ｒ値が１．２以上であるという特徴を有する。そのため、本発明の冷延鋼板は加工性に優れており、種々の加工を行うことにより、エキゾーストマニホールド、フロントパイプ、センターパイプ、触媒コンバータ外筒などの自動車の排気管部品を製造することができる。
上記のような特徴を有する本発明の冷延鋼板は、上記の熱延鋼板を焼鈍した後、７０％以上の圧下率で冷延して焼鈍することによって製造することができる。
冷延に先立ち、熱延鋼板の焼鈍が行われる。焼鈍は、再結晶組織が得られる温度で行われる。焼鈍温度は、熱延鋼板の組成に応じて適宜設定すればよく、特に限定されないが、通常９５０℃～１１５０℃である。焼鈍温度が９５０℃未満であると、再結晶組織が得られないことがある。一方、焼鈍温度が１１５０℃を超えると、結晶粒が粗大化することがある。 <Nb-containing ferritic stainless steel cold rolled steel sheet and method for producing the same>
The cold-rolled steel sheet of the present invention has a feature that the r value is 1.2 or more in addition to the characteristics of the hot-rolled steel sheet. Therefore, the cold-rolled steel sheet of the present invention is excellent in workability, and by performing various processes, it is possible to manufacture automobile exhaust pipe parts such as an exhaust manifold, a front pipe, a center pipe, and a catalytic converter outer cylinder.
The cold-rolled steel sheet of the present invention having the above-described characteristics can be manufactured by annealing the hot-rolled steel sheet and then cold-rolling and annealing at a rolling reduction of 70% or more.
Prior to cold rolling, the hot rolled steel sheet is annealed. Annealing is performed at a temperature at which a recrystallized structure is obtained. The annealing temperature may be appropriately set according to the composition of the hot-rolled steel sheet and is not particularly limited, but is usually 950 ° C. to 1150 ° C. When the annealing temperature is less than 950 ° C., a recrystallized structure may not be obtained. On the other hand, when the annealing temperature exceeds 1150 ° C., the crystal grains may become coarse.
冷延は、冷延鋼板のｒ値を１．２以上に高めるために、７０％以上の圧下率で行われる。圧下率が７０％未満であると、冷延鋼板のｒ値が１．２未満となる。
冷延後、冷延鋼板の焼鈍が行われる。焼鈍は、再結晶組織が得られる温度で行われる。焼鈍温度は、冷延鋼板の組成に応じて適宜設定すればよく、特に限定されないが、通常１０００℃～１１００℃である。焼鈍温度が１０００℃未満であると、再結晶組織が得られないことがある。焼鈍温度が１１００℃を超えると、結晶粒が粗大化し、加工時に肌荒れが生じて割れの原因となることがある。 Cold rolling is performed at a rolling reduction of 70% or more in order to increase the r value of the cold rolled steel sheet to 1.2 or more. When the rolling reduction is less than 70%, the r value of the cold-rolled steel sheet is less than 1.2.
After cold rolling, the cold rolled steel sheet is annealed. Annealing is performed at a temperature at which a recrystallized structure is obtained. The annealing temperature may be appropriately set according to the composition of the cold rolled steel sheet, and is not particularly limited, but is usually 1000 ° C. to 1100 ° C. When the annealing temperature is less than 1000 ° C., a recrystallized structure may not be obtained. When the annealing temperature exceeds 1100 ° C., the crystal grains are coarsened, and the surface may be roughened during processing to cause cracking.
冷延後、冷延鋼板の焼鈍が行われる。焼鈍は、再結晶組織が得られる温度で行われる。焼鈍温度は、冷延鋼板の組成に応じて適宜設定すればよく、特に限定されないが、通常１０００℃～１１００℃である。焼鈍温度が１０００℃未満であると、再結晶組織が得られないことがある。焼鈍温度が１１００℃を超えると、結晶粒が粗大化し、加工時に肌荒れが生じて割れの原因となることがある。 Cold rolling is performed at a rolling reduction of 70% or more in order to increase the r value of the cold rolled steel sheet to 1.2 or more. When the rolling reduction is less than 70%, the r value of the cold-rolled steel sheet is less than 1.2.
After cold rolling, the cold rolled steel sheet is annealed. Annealing is performed at a temperature at which a recrystallized structure is obtained. The annealing temperature may be appropriately set according to the composition of the cold rolled steel sheet, and is not particularly limited, but is usually 1000 ° C. to 1100 ° C. When the annealing temperature is less than 1000 ° C., a recrystallized structure may not be obtained. When the annealing temperature exceeds 1100 ° C., the crystal grains are coarsened, and the surface may be roughened during processing to cause cracking.
以下、実施例によって本発明を更に説明するが、本発明はこれらの実施例によって限定されるものではない。
表１に示す成分組成の鋼を溶製してステンレス鋼スラブとし、表１に示す条件で熱圧することによって所定の厚さを有するＮｂ含有フェライト系ステンレス熱延鋼板を得た。 EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited by these Examples.
A steel having a component composition shown in Table 1 was melted to form a stainless steel slab, and hot-pressed under the conditions shown in Table 1 to obtain an Nb-containing ferritic stainless steel hot rolled steel sheet having a predetermined thickness.
表１に示す成分組成の鋼を溶製してステンレス鋼スラブとし、表１に示す条件で熱圧することによって所定の厚さを有するＮｂ含有フェライト系ステンレス熱延鋼板を得た。 EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited by these Examples.
A steel having a component composition shown in Table 1 was melted to form a stainless steel slab, and hot-pressed under the conditions shown in Table 1 to obtain an Nb-containing ferritic stainless steel hot rolled steel sheet having a predetermined thickness.
次に、得られたＮｂ含有フェライト系ステンレス熱延鋼板から試験片を採取し、Ｎｂ炭窒化物の析出量、ラーベス相のサイズ、面積１０μｍ2あたりの粒径０．１μｍ以下のラーベス相の量及び靱性について評価を行った。
Ｎｂ炭窒化物の析出量、並びにラーベス相のサイズ及び個数は、上記した方法によって測定した。なお、Ｎｂ炭窒化物の析出量の測定においてＳＣＥ電位は４００ｍＶとした。また、靱性は、Ｕノッチ試験片でのシャルピー衝撃試験によって評価を行った。靭性の合否は、延性－脆性遷移温度(ＤＢＴＴ)が２０℃以下で靭性がある（〇）と評価した。
上記の各評価の結果を表２に示す。 Next, a test piece was collected from the obtained Nb-containing ferritic stainless steel hot-rolled steel sheet, the amount of Nb carbonitride deposited, the size of the Laves phase, and the amount of the Laves phase having a particle size of 0.1 μm or less per 10 μm 2 area. And toughness was evaluated.
The amount of Nb carbonitride deposited and the size and number of Laves phases were measured by the methods described above. Note that the SCE potential was 400 mV in the measurement of the amount of Nb carbonitride deposited. The toughness was evaluated by a Charpy impact test using a U-notch test piece. The acceptability of toughness was evaluated as having ductility (O) when the ductile-brittle transition temperature (DBTT) was 20 ° C. or less.
Table 2 shows the results of the above evaluations.
Ｎｂ炭窒化物の析出量、並びにラーベス相のサイズ及び個数は、上記した方法によって測定した。なお、Ｎｂ炭窒化物の析出量の測定においてＳＣＥ電位は４００ｍＶとした。また、靱性は、Ｕノッチ試験片でのシャルピー衝撃試験によって評価を行った。靭性の合否は、延性－脆性遷移温度(ＤＢＴＴ)が２０℃以下で靭性がある（〇）と評価した。
上記の各評価の結果を表２に示す。 Next, a test piece was collected from the obtained Nb-containing ferritic stainless steel hot-rolled steel sheet, the amount of Nb carbonitride deposited, the size of the Laves phase, and the amount of the Laves phase having a particle size of 0.1 μm or less per 10 μm 2 area. And toughness was evaluated.
The amount of Nb carbonitride deposited and the size and number of Laves phases were measured by the methods described above. Note that the SCE potential was 400 mV in the measurement of the amount of Nb carbonitride deposited. The toughness was evaluated by a Charpy impact test using a U-notch test piece. The acceptability of toughness was evaluated as having ductility (O) when the ductile-brittle transition temperature (DBTT) was 20 ° C. or less.
Table 2 shows the results of the above evaluations.
表２に示すように、ステンレス鋼スラブを熱延する際に、１０００℃～１１００℃の温度で６０秒以上保持すると共に仕上熱延温度を８５０℃以上とし、熱延後に５５０℃以下の巻取温度で巻取ることによって製造したＮｏ．１～８のＮｂ含有フェライト系ステンレス熱延鋼板は、Ｎｂ炭窒化物の析出量が０．２質量％以上、粒径０．１μｍ以下のラーベス相が面積１０μｍ2あたり１０個以下であり、靱性に優れることが確認された。
これに対して、ステンレス鋼スラブを熱延する際に１０００℃～１１００℃の温度での保持時間が短すぎたＮｏ．９～１２のＮｂ含有フェライト系ステンレス熱延鋼板は、Ｎｂ炭窒化物の析出量が少なく、ラーベス相の量も多くなり、靱性が十分でないことが分かった。 As shown in Table 2, when the stainless steel slab is hot rolled, it is held at a temperature of 1000 ° C. to 1100 ° C. for 60 seconds or more, and the finishing hot rolling temperature is set to 850 ° C. or higher. No. manufactured by winding at temperature. 1 to 8 Nb-containing ferritic stainless steel hot-rolled steel sheets have a Nb carbonitride precipitation amount of 0.2% by mass or more and 10 or less Laves phases with a particle size of 0.1 μm or less per 10 μm 2 area, and are tough. It was confirmed to be excellent.
On the other hand, when hot rolling a stainless steel slab, the holding time at a temperature of 1000 ° C. to 1100 ° C. was too short. It was found that 9 to 12 Nb-containing ferritic stainless steel hot-rolled steel sheets had a small amount of Nb carbonitride and a large amount of Laves phase and were not sufficiently tough.
これに対して、ステンレス鋼スラブを熱延する際に１０００℃～１１００℃の温度での保持時間が短すぎたＮｏ．９～１２のＮｂ含有フェライト系ステンレス熱延鋼板は、Ｎｂ炭窒化物の析出量が少なく、ラーベス相の量も多くなり、靱性が十分でないことが分かった。 As shown in Table 2, when the stainless steel slab is hot rolled, it is held at a temperature of 1000 ° C. to 1100 ° C. for 60 seconds or more, and the finishing hot rolling temperature is set to 850 ° C. or higher. No. manufactured by winding at temperature. 1 to 8 Nb-containing ferritic stainless steel hot-rolled steel sheets have a Nb carbonitride precipitation amount of 0.2% by mass or more and 10 or less Laves phases with a particle size of 0.1 μm or less per 10 μm 2 area, and are tough. It was confirmed to be excellent.
On the other hand, when hot rolling a stainless steel slab, the holding time at a temperature of 1000 ° C. to 1100 ° C. was too short. It was found that 9 to 12 Nb-containing ferritic stainless steel hot-rolled steel sheets had a small amount of Nb carbonitride and a large amount of Laves phase and were not sufficiently tough.
また、上記で得られたＮｂ含有フェライト系ステンレス熱延鋼板を用い、排気管フランジ部品への加工を模擬した冷間鍛造試験、プレス穴開け試験、切削試験を行った。その結果、Ｎｏ．１～８のＮｂ含有フェライト系ステンレス熱延鋼板では、所望の形状への加工性が良好であり、靱性不足などに起因する割れなども発生しなかった。これに対して、Ｎｏ．９～１２のＮｂ含有フェライト系ステンレス熱延鋼板では、靱性不足に起因した割れが発生した。
Further, using the Nb-containing ferritic stainless steel hot-rolled steel sheet obtained as described above, a cold forging test, a press hole drilling test, and a cutting test simulating processing of exhaust pipe flange parts were performed. As a result, no. In the Nb-containing ferritic stainless steel hot rolled steel sheets of 1 to 8, the workability to a desired shape was good, and cracks due to insufficient toughness did not occur. In contrast, no. In Nb-containing ferritic stainless steel hot rolled steel sheets of 9 to 12, cracks due to insufficient toughness occurred.
次に、上記で得られたＮｏ．１～７のＮｂ含有フェライト系ステンレス熱延鋼板を焼鈍した後、冷延し、さらに焼鈍してＮｂ含有フェライト系ステンレス冷延鋼板を得た。このときの製造条件については表３に示す。なお、Ｎｏ．９～１２のＮｂ含有フェライト系ステンレス熱延鋼板は靱性が低く、冷延を行うことができなかった。
次に、得られたＮｂ含有フェライト系ステンレス冷延鋼板についてｒ値を求めた。ｒ値は、Ｎｂ含有フェライト系ステンレス冷延鋼板からＪＩＳ１３号Ｂ引張試験片を採取し、１４．４％歪みを付与した後に、下記（１）式及び下記（２）式を用いて平均ｒ値を算出した。
ｒ＝ｌｎ（Ｗ0／Ｗ）／ｌｎ（ｔ0／ｔ） （１)
ここで、Ｗ0は引張前の板幅、Ｗは引張後の板幅、ｔ0は引張前の板厚、ｔは引張後の板厚である。
平均ｒ値＝（ｒ0＋２ｒ45＋ｒ90）／４ （２）
ここで、ｒ0は圧延方向のｒ値、ｒ45は圧延方向と４５°方向のｒ値、ｒ90は圧延方向と直角方向のｒ値である。
なお、複雑な形状が要求される自動車の排気管部品では、平均ｒ値が１．２以上であれば十分に加工できる特性であるため、平均ｒ値が１．２以上であれば加工性に優れると判断することができる。
上記の評価結果を表３に示す。 Next, No. obtained above. 1 to 7 Nb-containing ferritic stainless steel hot-rolled steel sheets were annealed, then cold-rolled, and further annealed to obtain Nb-containing ferritic stainless steel cold-rolled steel sheets. The manufacturing conditions at this time are shown in Table 3. In addition, No. Nb-containing ferritic stainless steel hot rolled steel sheets of 9 to 12 had low toughness and could not be cold rolled.
Next, r value was calculated | required about the obtained Nb containing ferritic stainless steel cold-rolled steel plate. The r value is an average r value using the following formula (1) and the following formula (2) after collecting a JIS No. 13 B tensile test piece from an Nb-containing ferritic stainless steel cold-rolled steel sheet and applying a 14.4% strain. Was calculated.
r = ln (W 0 / W) / ln (t 0 / t) (1)
Here, W 0 is the plate width before tension, W is the plate width after tension, t 0 is the plate thickness before tension, and t is the plate thickness after tension.
Average r value = (r 0 + 2r 45 + r 90 ) / 4 (2)
Here, r 0 is the r value in the rolling direction, r 45 is the r value in the rolling direction and the 45 ° direction, and r 90 is the r value in the direction perpendicular to the rolling direction.
It should be noted that the exhaust pipe parts of automobiles that require a complicated shape have characteristics that can be satisfactorily processed if the average r value is 1.2 or more. Therefore, if the average r value is 1.2 or more, the workability is improved. It can be judged that it is excellent.
The evaluation results are shown in Table 3.
次に、得られたＮｂ含有フェライト系ステンレス冷延鋼板についてｒ値を求めた。ｒ値は、Ｎｂ含有フェライト系ステンレス冷延鋼板からＪＩＳ１３号Ｂ引張試験片を採取し、１４．４％歪みを付与した後に、下記（１）式及び下記（２）式を用いて平均ｒ値を算出した。
ｒ＝ｌｎ（Ｗ0／Ｗ）／ｌｎ（ｔ0／ｔ） （１)
ここで、Ｗ0は引張前の板幅、Ｗは引張後の板幅、ｔ0は引張前の板厚、ｔは引張後の板厚である。
平均ｒ値＝（ｒ0＋２ｒ45＋ｒ90）／４ （２）
ここで、ｒ0は圧延方向のｒ値、ｒ45は圧延方向と４５°方向のｒ値、ｒ90は圧延方向と直角方向のｒ値である。
なお、複雑な形状が要求される自動車の排気管部品では、平均ｒ値が１．２以上であれば十分に加工できる特性であるため、平均ｒ値が１．２以上であれば加工性に優れると判断することができる。
上記の評価結果を表３に示す。 Next, No. obtained above. 1 to 7 Nb-containing ferritic stainless steel hot-rolled steel sheets were annealed, then cold-rolled, and further annealed to obtain Nb-containing ferritic stainless steel cold-rolled steel sheets. The manufacturing conditions at this time are shown in Table 3. In addition, No. Nb-containing ferritic stainless steel hot rolled steel sheets of 9 to 12 had low toughness and could not be cold rolled.
Next, r value was calculated | required about the obtained Nb containing ferritic stainless steel cold-rolled steel plate. The r value is an average r value using the following formula (1) and the following formula (2) after collecting a JIS No. 13 B tensile test piece from an Nb-containing ferritic stainless steel cold-rolled steel sheet and applying a 14.4% strain. Was calculated.
r = ln (W 0 / W) / ln (t 0 / t) (1)
Here, W 0 is the plate width before tension, W is the plate width after tension, t 0 is the plate thickness before tension, and t is the plate thickness after tension.
Average r value = (r 0 + 2r 45 + r 90 ) / 4 (2)
Here, r 0 is the r value in the rolling direction, r 45 is the r value in the rolling direction and the 45 ° direction, and r 90 is the r value in the direction perpendicular to the rolling direction.
It should be noted that the exhaust pipe parts of automobiles that require a complicated shape have characteristics that can be satisfactorily processed if the average r value is 1.2 or more. Therefore, if the average r value is 1.2 or more, the workability is improved. It can be judged that it is excellent.
The evaluation results are shown in Table 3.
表３に示すように、７０％以上の圧下率で冷延したＮｏ．１～５及び７のＮｂ含有フェライト系ステンレス冷延鋼板は、ｒ値が１．２以上であり、加工性に優れることが確認された。
これに対して、７０％未満の圧下率で冷延したＮｏ．６のＮｂ含有フェライト系ステンレス冷延鋼板は、ｒ値が１．２未満であり、加工性が十分でないことが分かった。 As shown in Table 3, No. cold-rolled at a rolling reduction of 70% or more. The Nb-containing ferritic stainless steel cold-rolled steel sheets 1 to 5 and 7 have an r value of 1.2 or more and were confirmed to be excellent in workability.
On the other hand, No. cold-rolled with a rolling reduction of less than 70%. No. 6 Nb-containing ferritic stainless steel cold-rolled steel sheet had an r value of less than 1.2, indicating that workability was not sufficient.
これに対して、７０％未満の圧下率で冷延したＮｏ．６のＮｂ含有フェライト系ステンレス冷延鋼板は、ｒ値が１．２未満であり、加工性が十分でないことが分かった。 As shown in Table 3, No. cold-rolled at a rolling reduction of 70% or more. The Nb-containing ferritic stainless steel cold-rolled steel sheets 1 to 5 and 7 have an r value of 1.2 or more and were confirmed to be excellent in workability.
On the other hand, No. cold-rolled with a rolling reduction of less than 70%. No. 6 Nb-containing ferritic stainless steel cold-rolled steel sheet had an r value of less than 1.2, indicating that workability was not sufficient.
以上の結果からわかるように、本発明によれば、靱性及び加工性に優れたＮｂ含有フェライト系ステンレス熱延鋼板及びその製造方法を提供することができる。また、本発明によれば、加工性に優れたＮｂ含有フェライト系ステンレス冷延鋼板及びその製造方法を提供することができる。
As can be seen from the above results, according to the present invention, it is possible to provide an Nb-containing ferritic stainless steel hot rolled steel sheet excellent in toughness and workability and a method for producing the same. Moreover, according to this invention, the Nb containing ferritic stainless steel cold-rolled steel plate excellent in workability and its manufacturing method can be provided.
なお、本出願は、２０１６年２月２日に出願した日本国特許出願第２０１６－０１７８８３号に基づく優先権を主張するものであり、この日本国特許出願の全内容を本出願に援用する。
Note that this application claims priority based on Japanese Patent Application No. 2016-017883 filed on Feb. 2, 2016, and the entire contents of this Japanese patent application are incorporated herein by reference.
Claims (9)
- Ｃ：０．０３０質量％以下、Ｓｉ：２．００質量％以下、Ｍｎ：２．００質量％以下、Ｐ：０．０５０質量％以下、Ｓ：０．０４０質量％以下、Ｃｒ：１０．００質量％～２５．００質量％、Ｎ：０．０３０質量％以下、Ｎｂ：０．０１質量％～０．８０質量％を含有し、残部がＦｅ及び不可避的不純物からなる組成を有するＮｂ含有フェライト系ステンレス熱延鋼板であって、
Ｎｂ炭窒化物の析出量が０．２質量％以上であり、且つ粒径０．１μｍ以下のラーベス相が面積１０μｍ2あたり１０個以下であることを特徴とするＮｂ含有フェライト系ステンレス熱延鋼板。 C: 0.030 mass% or less, Si: 2.00 mass% or less, Mn: 2.00 mass% or less, P: 0.050 mass% or less, S: 0.040 mass% or less, Cr: 10.00 Nb-containing ferrite having a composition containing mass% to 25.00 mass%, N: 0.030 mass% or less, Nb: 0.01 mass% to 0.80 mass%, the balance being Fe and inevitable impurities Stainless steel hot-rolled steel sheet,
Nb-containing ferritic stainless steel hot-rolled steel sheet, wherein the precipitation amount of Nb carbonitride is 0.2% by mass or more and the number of Laves phases having a particle size of 0.1 μm or less is 10 or less per 10 μm 2 area . - Ｎｉ：２．００質量％以下、Ｍｏ：２．５０質量％以下、Ｃｕ：１．８０質量％以下、Ｃｏ：０．５０質量％以下、Ａｌ：０．５０質量％以下、Ｗ：１．８０質量％以下、Ｖ：０．３０質量％以下、Ｔｉ：０．５０質量％以下、Ｚｒ：０．２０質量％以下、Ｂ：０．００５０質量％以下、希土類元素：０．１００質量％以下、Ｃａ：０．００５０質量％以下の１種以上をさらに含有する組成を有することを特徴とする請求項１に記載のＮｂ含有フェライト系ステンレス熱延鋼板。 Ni: 2.00 mass% or less, Mo: 2.50 mass% or less, Cu: 1.80 mass% or less, Co: 0.50 mass% or less, Al: 0.50 mass% or less, W: 1.80 Mass% or less, V: 0.30 mass% or less, Ti: 0.50 mass% or less, Zr: 0.20 mass% or less, B: 0.0050 mass% or less, rare earth element: 0.100 mass% or less, The Nb-containing ferritic stainless steel hot-rolled steel sheet according to claim 1, wherein the Nb-containing ferritic stainless steel sheet has a composition further containing one or more of Ca: 0.0050 mass% or less.
- 排気管フランジ部品の製造に用いられることを特徴とする請求項１又は２に記載のＮｂ含有フェライト系ステンレス熱延鋼板。 The Nb-containing ferritic stainless steel hot-rolled steel sheet according to claim 1 or 2, which is used for manufacturing an exhaust pipe flange part.
- Ｃ：０．０３０質量％以下、Ｓｉ：２．００質量％以下、Ｍｎ：２．００質量％以下、Ｐ：０．０５０質量％以下、Ｓ：０．０４０質量％以下、Ｃｒ：１０．００質量％～２５．００質量％、Ｎ：０．０３０質量％以下、Ｎｂ：０．０１質量％～０．８０質量％を含有し、残部がＦｅ及び不可避的不純物からなる組成を有するステンレス鋼スラブを熱延する際に、１０００℃～１１００℃の温度で６０秒以上保持すると共に仕上熱延温度を８５０℃以上とし、熱延後に５５０℃以下の巻取温度で巻取ることを特徴とするＮｂ含有フェライト系ステンレス熱延鋼板の製造方法。 C: 0.030 mass% or less, Si: 2.00 mass% or less, Mn: 2.00 mass% or less, P: 0.050 mass% or less, S: 0.040 mass% or less, Cr: 10.00 A stainless steel slab having a composition containing mass% to 25.00 mass%, N: 0.030 mass% or less, Nb: 0.01 mass% to 0.80 mass%, the balance being Fe and inevitable impurities When hot rolling, Nb is held at a temperature of 1000 ° C. to 1100 ° C. for 60 seconds or more, and the finish hot rolling temperature is set to 850 ° C. or higher, and after the hot rolling, winding is performed at a winding temperature of 550 ° C. or lower. A method for producing a ferritic stainless steel hot-rolled steel sheet.
- Ｎｉ：２．００質量％以下、Ｍｏ：２．５０質量％以下、Ｃｕ：１．８０質量％以下、Ｃｏ：０．５０質量％以下、Ａｌ：０．５０質量％以下、Ｗ：１．８０質量％以下、Ｖ：０．３０質量％以下、Ｔｉ：０．５０質量％以下、Ｚｒ：０．２０質量％以下、Ｂ：０．００５０質量％以下、希土類元素：０．１００質量％以下、Ｃａ：０．００５０質量％以下の１種以上をさらに含有する組成を有することを特徴とする請求項４に記載のＮｂ含有フェライト系ステンレス熱延鋼板の製造方法。 Ni: 2.00 mass% or less, Mo: 2.50 mass% or less, Cu: 1.80 mass% or less, Co: 0.50 mass% or less, Al: 0.50 mass% or less, W: 1.80 Mass% or less, V: 0.30 mass% or less, Ti: 0.50 mass% or less, Zr: 0.20 mass% or less, B: 0.0050 mass% or less, rare earth element: 0.100 mass% or less, The method for producing an Nb-containing ferritic stainless steel hot-rolled steel sheet according to claim 4, wherein the composition further contains one or more of Ca: 0.0050 mass% or less.
- Ｃ：０．０３０質量％以下、Ｓｉ：２．００質量％以下、Ｍｎ：２．００質量％以下、Ｐ：０．０５０質量％以下、Ｓ：０．０４０質量％以下、Ｃｒ：１０．００質量％～２５．００質量％、Ｎ：０．０３０質量％以下、Ｎｂ：０．０１質量％～０．８０質量％を含有し、残部がＦｅ及び不可避的不純物からなる組成を有するＮｂ含有フェライト系ステンレス冷延鋼板であって、
Ｎｂ炭窒化物の析出量が０．２質量％以上であり、粒径０．１μｍ以下のラーベス相が面積１０μｍ2あたり１０個以下であり、且つｒ値が１．２以上であることを特徴とするＮｂ含有フェライト系ステンレス冷延鋼板。 C: 0.030 mass% or less, Si: 2.00 mass% or less, Mn: 2.00 mass% or less, P: 0.050 mass% or less, S: 0.040 mass% or less, Cr: 10.00 Nb-containing ferrite having a composition containing mass% to 25.00 mass%, N: 0.030 mass% or less, Nb: 0.01 mass% to 0.80 mass%, the balance being Fe and inevitable impurities Stainless steel cold-rolled steel sheet,
The precipitation amount of Nb carbonitride is 0.2% by mass or more, the number of Laves phases having a particle size of 0.1 μm or less is 10 or less per 10 μm 2 , and the r value is 1.2 or more. Nb-containing ferritic stainless steel cold-rolled steel sheet. - Ｎｉ：２．００質量％以下、Ｍｏ：２．５０質量％以下、Ｃｕ：１．８０質量％以下、Ｃｏ：０．５０質量％以下、Ａｌ：０．５０質量％以下、Ｗ：１．８０質量％以下、Ｖ：０．３０質量％以下、Ｔｉ：０．５０質量％以下、Ｚｒ：０．２０質量％以下、Ｂ：０．００５０質量％以下、希土類元素：０．１００質量％以下、Ｃａ：０．００５０質量％以下の１種以上をさらに含有する組成を有することを特徴とする請求項６に記載のＮｂ含有フェライト系ステンレス冷延鋼板。 Ni: 2.00 mass% or less, Mo: 2.50 mass% or less, Cu: 1.80 mass% or less, Co: 0.50 mass% or less, Al: 0.50 mass% or less, W: 1.80 Mass% or less, V: 0.30 mass% or less, Ti: 0.50 mass% or less, Zr: 0.20 mass% or less, B: 0.0050 mass% or less, rare earth element: 0.100 mass% or less, The Nb-containing ferritic stainless steel cold-rolled steel sheet according to claim 6, wherein the Nb-containing ferritic stainless steel cold-rolled steel sheet has a composition further containing one or more of Ca: 0.0050% by mass or less.
- 排気管部品の製造に用いられることを特徴とする請求項６又は７に記載のＮｂ含有フェライト系ステンレス冷延鋼板。 The Nb-containing ferritic stainless steel cold-rolled steel sheet according to claim 6 or 7, wherein the Nb-containing ferritic stainless steel cold-rolled steel sheet is used for manufacturing exhaust pipe parts.
- 請求項１又は２に記載のＮｂ含有フェライト系ステンレス熱延鋼板を焼鈍した後、７０％以上の圧下率で冷延して焼鈍することを特徴とするＮｂ含有フェライト系ステンレス冷延鋼板の製造方法。 A method for producing an Nb-containing ferritic stainless steel cold-rolled steel sheet, comprising annealing the Nb-containing ferritic stainless steel hot-rolled steel sheet according to claim 1 or 2 and then cold-rolling and annealing at a rolling reduction of 70% or more. .
Priority Applications (10)
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| JP2017549433A JP6383503B2 (en) | 2016-02-02 | 2017-01-31 | Nb-containing ferritic stainless steel hot-rolled steel sheet and method for producing the same, Nb-containing ferritic stainless steel cold-rolled steel sheet and method for producing the same |
| US16/061,159 US20180363089A1 (en) | 2016-02-02 | 2017-01-31 | HOT-ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME, AND COLD-ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME |
| KR1020187018664A KR102267129B1 (en) | 2016-02-02 | 2017-01-31 | Nb-containing ferritic stainless hot-rolled steel sheet and manufacturing method thereof, Nb-containing ferritic stainless cold-rolled stainless steel sheet and manufacturing method thereof |
| CA3009133A CA3009133A1 (en) | 2016-02-02 | 2017-01-31 | Hot-rolled nb-containing ferritic stainless steel sheet and method for producing same, and cold-rolled nb-containing ferritic stainless steel sheet and method for producing same |
| EP20171581.0A EP3708690A1 (en) | 2016-02-02 | 2017-01-31 | Cold rolled nb-containing ferritic stainless steel sheet and method for producing same |
| CN201780007794.6A CN108495944B (en) | 2016-02-02 | 2017-01-31 | Hot-rolled Nb-containing ferritic stainless steel sheet and method for producing same, and cold-rolled Nb-containing ferritic stainless steel sheet and method for producing same |
| EP17747396.4A EP3388542A4 (en) | 2016-02-02 | 2017-01-31 | HOT ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME, AND COLD ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME |
| MX2018009402A MX2018009402A (en) | 2016-02-02 | 2017-01-31 | HOT ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME, AND COLD ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME. |
| RU2018119752A RU2712668C1 (en) | 2016-02-02 | 2017-01-31 | Hot-rolled sheet from nb-containing ferritic stainless steel and method for manufacture thereof, and cold-rolled sheet from nb-containing ferritic stainless steel and method for manufacture thereof |
| US16/845,327 US20200255919A1 (en) | 2016-02-02 | 2020-04-10 | HOT-ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME, AND COLD-ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME |
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| US16/845,327 Division US20200255919A1 (en) | 2016-02-02 | 2020-04-10 | HOT-ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME, AND COLD-ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME |
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| Publication number | Publication date |
|---|---|
| EP3388542A4 (en) | 2019-11-06 |
| US20200255919A1 (en) | 2020-08-13 |
| JP6383503B2 (en) | 2018-08-29 |
| CA3009133A1 (en) | 2017-08-10 |
| JPWO2017135240A1 (en) | 2018-02-08 |
| KR20180109865A (en) | 2018-10-08 |
| TWI707049B (en) | 2020-10-11 |
| TW201732055A (en) | 2017-09-16 |
| EP3708690A1 (en) | 2020-09-16 |
| EP3388542A1 (en) | 2018-10-17 |
| KR102267129B1 (en) | 2021-06-18 |
| US20180363089A1 (en) | 2018-12-20 |
| CN108495944B (en) | 2020-12-25 |
| MX2018009402A (en) | 2018-12-19 |
| RU2712668C1 (en) | 2020-01-30 |
| CN108495944A (en) | 2018-09-04 |
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