WO2020084987A1 - Ferrite stainless hot-rolled-and-annealed steel sheet and production method for same - Google Patents
Ferrite stainless hot-rolled-and-annealed steel sheet and production method for same Download PDFInfo
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- WO2020084987A1 WO2020084987A1 PCT/JP2019/037430 JP2019037430W WO2020084987A1 WO 2020084987 A1 WO2020084987 A1 WO 2020084987A1 JP 2019037430 W JP2019037430 W JP 2019037430W WO 2020084987 A1 WO2020084987 A1 WO 2020084987A1
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 84
- 239000010959 steel Substances 0.000 title claims abstract description 84
- 229910000859 α-Fe Inorganic materials 0.000 title claims abstract description 32
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- 239000013078 crystal Substances 0.000 claims abstract description 38
- 229910052751 metal Inorganic materials 0.000 claims abstract description 19
- 239000002184 metal Substances 0.000 claims abstract description 19
- 239000012535 impurity Substances 0.000 claims abstract description 7
- 238000000137 annealing Methods 0.000 claims description 39
- 229910001220 stainless steel Inorganic materials 0.000 claims description 30
- 238000005098 hot rolling Methods 0.000 claims description 28
- 238000000034 method Methods 0.000 claims description 25
- 229910052791 calcium Inorganic materials 0.000 claims description 3
- 238000004080 punching Methods 0.000 abstract description 46
- 230000007797 corrosion Effects 0.000 abstract description 34
- 238000005260 corrosion Methods 0.000 abstract description 34
- 239000000203 mixture Substances 0.000 abstract description 10
- 238000005336 cracking Methods 0.000 abstract description 5
- 229910052748 manganese Inorganic materials 0.000 abstract description 5
- 229910052698 phosphorus Inorganic materials 0.000 abstract description 5
- 230000000694 effects Effects 0.000 description 35
- 229910001566 austenite Inorganic materials 0.000 description 12
- 229910052757 nitrogen Inorganic materials 0.000 description 11
- 229910052761 rare earth metal Inorganic materials 0.000 description 10
- 150000002910 rare earth metals Chemical class 0.000 description 10
- 229910000734 martensite Inorganic materials 0.000 description 9
- 238000001953 recrystallisation Methods 0.000 description 9
- 238000005096 rolling process Methods 0.000 description 9
- 239000007789 gas Substances 0.000 description 8
- 239000007921 spray Substances 0.000 description 8
- 230000007423 decrease Effects 0.000 description 7
- 229910052759 nickel Inorganic materials 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 6
- 229910052804 chromium Inorganic materials 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 150000003839 salts Chemical class 0.000 description 6
- 206010070834 Sensitisation Diseases 0.000 description 5
- 238000007670 refining Methods 0.000 description 5
- 230000008313 sensitization Effects 0.000 description 5
- 229910052719 titanium Inorganic materials 0.000 description 5
- 238000003466 welding Methods 0.000 description 5
- 238000005266 casting Methods 0.000 description 4
- 229910052758 niobium Inorganic materials 0.000 description 4
- 238000007665 sagging Methods 0.000 description 4
- 239000010935 stainless steel Substances 0.000 description 4
- 229910052796 boron Inorganic materials 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 229910052750 molybdenum Inorganic materials 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 239000011780 sodium chloride Substances 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 238000004804 winding Methods 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000009749 continuous casting Methods 0.000 description 2
- 238000001887 electron backscatter diffraction Methods 0.000 description 2
- 229910001651 emery Inorganic materials 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 230000001376 precipitating effect Effects 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- -1 35 ° C. Substances 0.000 description 1
- 229910004337 Ti-Ni Inorganic materials 0.000 description 1
- 229910011209 Ti—Ni Inorganic materials 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000005431 greenhouse gas Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N hydrochloric acid Substances Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- 238000010191 image analysis Methods 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
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- 230000008646 thermal stress Effects 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
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Classifications
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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
-
- 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
-
- 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
-
- 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
- C21D6/007—Heat treatment of ferrous alloys containing Co
-
- 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
-
- 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
-
- 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
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
-
- C—CHEMISTRY; METALLURGY
- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
-
- 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
- C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—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
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—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
- C22C38/52—Ferrous alloys, e.g. steel alloys containing chromium with nickel with cobalt
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
Definitions
- the present invention relates to a hot rolled annealed ferritic stainless steel sheet having excellent workability suitable for application to flanges and the like, and a method for manufacturing the same.
- Exhaust gas generated by the engine is released to the atmosphere via exhaust gas recirculation (Exhaust Gas Recirculation, EGR) system and exhaust system parts such as muffler.
- EGR exhaust Gas Recirculation
- Each component of such an automobile exhaust system is fastened via a flange in order to prevent gas leakage.
- the flange applied to the exhaust system component needs to have sufficient dimensional accuracy as a fastening component.
- stainless steel is superior to ordinary steel in high-temperature strength and corrosion resistance, especially high-strength ferritic stainless steel sheet with a relatively small coefficient of thermal expansion and in which thermal stress is unlikely to occur (for example, ASTM A240 / 240M-S40975 ( 11 mass% Cr-Ti-Ni steel having a large plate thickness (for example, a plate thickness of 5 mm or more) is being applied.
- the flange used for the exhaust system has a large plate thickness (often 5 mm or more), there is a problem that the flange part may not be manufactured properly due to cracking during punching during manufacturing the flange.
- Patent Document 1 in mass%, C: 0.015% or less, Si: 0.01 to 0.4%, Mn: 0.01 to 0.8%, P: 0.04% or less, S: 0.01% or less, Cr: 14.0 to less than 18.0%, Ni: 0.05 to 1%, Nb: 0.3 to 0.6%, Ti: 0.05% or less, N: 0.020% or less, Al: 0.10% or less, B: 0.0002 to 0.0020%, the balance being Fe and unavoidable impurities, and Nb, C and Disclosed is a ferritic stainless hot rolled steel sheet having a N content satisfying Nb / (C + N) ⁇ 16, a Charpy impact value at 0 ° C. of 10 J / cm 2 or more, and a sheet thickness of 5.0 to 9.0 mm. Has been done.
- the inventors of the present invention prototyped a ferritic stainless steel plate having a plate thickness of 10 mm having a steel component conforming to ASTM A240 / 240M-S40975 by using the method disclosed in Patent Document 1, and provided a flange having a 20 mm ⁇ hole with a flange. It was manufactured by punching with a clearance of 10%. As a result, none of the cracks due to punching occurred, but the outer peripheral dimension and / or the central hole dimension of the flange may exceed the allowable tolerance of the part, and it may not be sufficient to apply to thick flanges. It became clear.
- the present invention solves the above problems, has sufficient corrosion resistance, and can obtain a predetermined dimensional accuracy without cracking during punching into a thick flange, and a ferritic stainless steel with excellent punching workability.
- An object of the present invention is to provide annealed steel sheet and a manufacturing method thereof.
- the present inventors conducted a detailed study to solve the above problems.
- the steel sheet should have a ferrite single-phase structure and its average crystal grain size should be controlled within the range of 5 to 20 ⁇ m. I found out that.
- hot rolling is performed on a ferritic stainless steel having an appropriate component, and the obtained hot rolled steel sheet is subjected to appropriate conditions to be a ferrite single phase region, specifically, 600 ° C or higher and lower than 750 ° C. It has been found that by performing hot-rolled sheet annealing for 1 minute to 24 hours, the metal structure can be controlled to a ferrite single phase and the average crystal grain size can be controlled to the range of 5 to 20 ⁇ m.
- the present invention has been made based on the above findings, and has the following gist. [1]% by mass, C: 0.001 to 0.020%, Si: 0.05 to 1.00%, Mn: 0.05 to 1.00%, P: 0.04% or less, S: 0.01% or less, Al: 0.01 to 0.10%, Cr: 10.0 to 20.0%, Ni: 0.50 to 2.00%, Ti: 0.10 to 0.40%, N: 0.001 to 0.020%, a balance of Fe and unavoidable impurities in the balance, and a ferritic stainless steel with a metallic structure of a ferrite single-phase structure with an average crystal grain size of 5 to 20 ⁇ m. Annealed steel sheet.
- Sufficient corrosion resistance in the present invention means a salt water spray cycle test (salt water spray (5 mass% NaCl, 35% by mass, 35% by mass NaCl, 35% by weight) on a steel plate whose end surface is sealed after polishing the surface with # 600 emery paper.
- salt water spray 5 mass% NaCl, 35% by mass, 35% by mass NaCl, 35% by weight
- C., spray 2 hr ⁇ dry (60 ° C., 4 hr, relative humidity 40%) ⁇ wet (50 ° C., 2 hr, relative humidity ⁇ 95%)
- a 100 mm ⁇ 100 mm test piece was sampled from a hot-rolled annealed steel sheet, and a hole of ⁇ 20 mm (tolerance ⁇ 0.1 mm) was formed in the center of the test piece.
- a crank press equipped with an upper die (punch) having a 20 mm diameter columnar cutting blade and a lower die (die) having holes with a diameter of 20 mm or more, five test pieces are prepared by punching. .
- the punching process is performed by selecting the hole diameter on the lower mold side in accordance with the thickness of the test piece plate so that the clearance between the upper mold and the lower mold is 10%.
- the clearance (C) [%], the diameter of the hole of the die (the inner diameter of the die) (Dd) [mm] and the diameter of the punch (Dp) [mm] are also the plate thickness (t) [mm]. Including, it is expressed by the following equation (1).
- C (Dd ⁇ Dp) ⁇ (2 ⁇ t) ⁇ 100 ... Equation (1)
- the ferritic stainless steel hot rolled annealed steel sheet of the present invention in mass%, is C: 0.001 to 0.020%, Si: 0.05 to 1.00%, Mn: 0.05 to 1.00%, P : 0.04% or less, S: 0.01% or less, Al: 0.01 to 0.10%, Cr: 10.0 to 20.0%, Ni: 0.50 to 2.00%, Ti: 0.10 to 0.40%, N: 0.001 to 0.020%, with the balance being Fe and inevitable impurities, and having a metal structure of 5 to 20 ⁇ m in average crystal grain size. It is a ferritic stainless steel hot-rolled and annealed steel sheet having a ferrite single-phase structure.
- ASTM A240 / 240M-S40975 (the composition of components is% by mass, C ⁇ 0.03%, Si ⁇ 1.00%, Mn ⁇ 1.00%, P ⁇ 0.040%, S ⁇ 0.030%, Cr: 10.5 to 11.7%, Ni: 0.50 to 1.00%, N ⁇ 0.03%, Ti: 6 ⁇ (C + N) to 0.74% , The balance Fe and unavoidable impurities.)
- Using various ferritic stainless steel plates with a plate thickness of 10 mm a flange having a hole of 20 mm ⁇ was punched with a clearance of 10%. As a result, it was found that the cracks due to punching did not occur in either case, but the outer peripheral dimension of the flange and / or the central hole dimension may exceed the allowable tolerance of the component.
- the present inventors examined in detail the cause that the dimensional accuracy in punching greatly differs depending on the steel sheet.
- the average grain size of the steel sheet subjected to punching was less than 5 ⁇ m
- the dimension of the part after punching was smaller than the allowable tolerance
- the average grain size of the steel sheet was more than 20 ⁇ m. It was found that in the case of punching, the part size after punching tends to be larger than the allowable tolerance. From this, the present inventors can not stably obtain sufficient dimensional accuracy in the punching process, when the average crystal grain size is too small, the steel plate is too hard during the punching process. It was found that this is due to the fact that the shear surface ratio of No. 2 was small, and that when the average crystal grain size was excessively large, large sagging or burrs occurred during punching.
- the inventors of the present invention have a method of obtaining a ferritic stainless steel sheet having a ferrite single-phase structure having an average crystal grain size of 5 to 20 ⁇ m in terms of steel composition, hot rolling method and hot rolled sheet annealing method. Diligently studied. As a result, the steel components, especially Cr and Ni contents were controlled in an appropriate range to generate an austenite phase and a ferrite phase in the hot rolling step, and then hot rolling was performed, followed by the ferrite single phase temperature range. It was found that it is effective to carry out hot-rolled sheet annealing in the appropriate temperature range.
- the hot-rolled sheet annealing process is performed by holding the ferrite single-phase temperature range in an appropriate temperature range, specifically, 600 ° C or higher and lower than 750 ° C for 1 minute to 24 hours.
- an appropriate temperature range specifically, 600 ° C or higher and lower than 750 ° C for 1 minute to 24 hours.
- recrystallization of the ferrite phase existing in the metal structure after hot rolling and transformation of the martensite phase into the ferrite phase are caused to obtain a ferrite single phase structure.
- the hot-rolled sheet annealing temperature is less than 600 ° C., recrystallization of the ferrite phase and transformation of the martensite phase into the ferrite phase become insufficient, and punching cracks due to excessive hardening of the steel sheet occur. It tends to occur.
- the annealing temperature is 750 ° C. or higher
- the crystal grains become excessively coarse and the average crystal grain size exceeds 20 ⁇ m, and large sagging or burrs are likely to occur during the punching process, and the predetermined dimensional accuracy during the punching process is not achieved. I can't get it. If the holding time is less than 1 minute, recrystallization of the ferrite phase and transformation of the martensite phase to the ferrite phase become insufficient, and punching cracks due to excessive hardening of the steel sheet are likely to occur.
- the holding time exceeds 24 hours, the crystal grains become excessively coarse and the average crystal grain size exceeds 20 ⁇ m, and large sagging or burrs are likely to occur during punching, so that the prescribed dimensional accuracy can be obtained during punching. I can't. Therefore, in the present invention, it is necessary to perform hot rolled sheet annealing in the temperature range of 600 ° C. or higher and lower than 750 ° C. for 1 minute to 24 hours.
- the metal structure is a ferrite single-phase structure
- the average crystal grain size of the ferrite single-phase structure is 5 to 20 ⁇ m.
- the average crystal grain size is 7 ⁇ m or more, and more preferably 10 ⁇ m or more.
- the average crystal grain size is preferably 18 ⁇ m or less, more preferably 15 ⁇ m or less.
- a test piece for observing a structure is taken from the center of the plate width, the cross section in the rolling direction is mirror-polished, and then measured and analyzed in the visual field including the total thickness by using the SEM / EBSD method, A boundary having an orientation difference of 15 ° or more can be defined as a grain boundary and can be obtained based on the Area method.
- the plate thickness of the ferritic stainless steel hot-rolled annealed steel sheet of the present invention is not particularly limited, but is preferably a plate thickness applicable to a thick flange, and is preferably 5.0 mm or more, more preferably , 8.0 mm or more.
- the plate thickness is preferably 15.0 mm or less, more preferably 13.0 mm or less.
- C 0.001 to 0.020% If the content of C exceeds 0.020%, the workability and the corrosion resistance of the welded part are significantly reduced. The smaller the C content is, the more preferable it is from the viewpoint of corrosion resistance and workability. However, if the C content is less than 0.001%, refining takes time, which is not preferable in terms of production. Therefore, the C content is set to the range of 0.001 to 0.020%. Preferably, the C content is 0.003% or more, more preferably 0.004% or more. Further, the C content is preferably 0.015% or less, and more preferably 0.012% or less.
- Si 0.05-1.00%
- Si has the effect of concentrating in the oxide film formed during welding to improve the corrosion resistance of the welded portion, and is also a useful element as a deoxidizing element in the steelmaking process. These effects are obtained by containing 0.05% or more of Si, and the larger the content, the greater the effects.
- the Si content is set to 0.05 to 1.00%.
- the Si content is preferably 0.10% or more, more preferably 0.15% or more. Further, the Si content is preferably 0.60% or less, and more preferably 0.40% or less.
- Mn 0.05-1.00%
- Mn is an austenite forming element, and has an effect of increasing the amount of austenite generated during heating before rolling in the hot rolling step. It also acts as a deoxidizer. In order to obtain the effect, it is necessary to contain 0.05% or more of Mn. However, if the Mn content exceeds 1.00%, the precipitation of MnS, which is the starting point of corrosion, is promoted, and the corrosion resistance decreases. Therefore, the Mn content is set to 0.05 to 1.00%.
- the Mn content is 0.10% or more, more preferably 0.15% or more. Further, the Mn content is preferably 0.60% or less, and more preferably 0.30% or less.
- P 0.04% or less
- P is an element that is inevitably contained in steel, but it is an element harmful to corrosion resistance and workability, so it is preferable to reduce it as much as possible.
- the P content exceeds 0.04%, solid-solution strengthening significantly reduces the workability. Therefore, the P content is 0.04% or less.
- the P content is 0.03% or less.
- S 0.01% or less
- S is an element that is inevitably contained in steel similarly to P, but it is an element harmful to corrosion resistance and workability, so it is preferable to reduce it as much as possible.
- the S content exceeds 0.01%, the corrosion resistance is significantly reduced. Therefore, the S content is 0.01% or less.
- the S content is 0.008% or less. More preferably, the S content is 0.003% or less.
- Al 0.01 to 0.10%
- Al is an effective deoxidizer. Furthermore, since Al has a stronger affinity for nitrogen than Cr, when nitrogen penetrates into the welded portion, it has the effect of precipitating nitrogen as Al nitride instead of Cr nitride and suppressing sensitization. These effects are obtained by containing Al by 0.01% or more. However, if Al is contained in excess of 0.10%, the meltability during welding is deteriorated and the welding workability is deteriorated, which is not preferable. Therefore, the Al content is set to the range of 0.01 to 0.10%. The Al content is preferably 0.02% or more, more preferably 0.03% or more. Further, the Al content is preferably 0.06% or less, and more preferably 0.04% or less.
- Cr 10.0-20.0% Cr is the most important element for ensuring the corrosion resistance of stainless steel. If the content is less than 10.0%, sufficient corrosion resistance cannot be obtained in an automobile exhaust gas atmosphere. On the other hand, if Cr is contained in excess of 20.0%, even if a predetermined amount of Ni is contained, the amount of austenite phase generated in the hot rolling process is insufficient, and the metal structure is refined in the hot rolling process. The effect becomes insufficient, and the average crystal grain size after hot-rolled sheet annealing exceeds 20 ⁇ m, and a predetermined dimensional accuracy cannot be obtained during punching. Therefore, the Cr content is set in the range of 10.0 to 20.0%. Preferably, the Cr content is in the range of 10.0 to 17.0%. More preferably, the Cr content is 10.5% or more, and further preferably 11.2% or more. Further, the Cr content is more preferably 12.0% or less, and further preferably 11.7% or less.
- Ni is an austenite-forming element and has an effect of increasing the amount of austenite generated during heating before rolling in the hot rolling step.
- the austenite phase is generated at the time of heating in the hot rolling step by controlling the contents of Cr and Ni to predetermined amounts. Due to the formation of the austenite phase, the coarse metal structure formed during casting is refined, and the austenite phase undergoes dynamic and / or static recrystallization during hot rolling. The structure is further refined, and as a result, it contributes to the refinement of the metal structure after hot-rolled sheet annealing. These effects can be obtained by containing 0.50% or more of Ni.
- the Ni content is 0.50 to 2.00%.
- the Ni content is preferably 0.60% or more, more preferably 0.70% or more. More preferably, it is 0.75% or more. Further, the Ni content is more preferably 1.50% or less, and further preferably 1.00% or less.
- Ti 0.10 to 0.40% Ti binds preferentially to C and N, suppresses the precipitation of Cr carbonitrides, lowers the recrystallization temperature, and suppresses the deterioration of corrosion resistance due to sensitization due to the precipitation of Cr carbonitrides. There is. To obtain these effects, it is necessary to contain 0.10% or more of Ti. However, if the Ti content exceeds 0.40%, coarse Ti carbonitrides are generated in the casting process, the toughness of the steel sheet is significantly reduced, and surface defects are caused, which is not preferable in manufacturing. Therefore, the Ti content is set to 0.10 to 0.40%. Preferably, the Ti content is 0.15% or more, more preferably 0.20% or more.
- the Ti content is preferably 0.35% or less, and more preferably the Ti content is 0.30% or less. From the viewpoint of weld corrosion resistance, it is preferable to set the Ti content to satisfy the formula: Ti / (C + N) ⁇ 8 (Ti, C and N in the formula are the contents (mass%) of each element). .
- the N content is set in the range of 0.001 to 0.020%.
- the N content is 0.005% or more, more preferably 0.007% or more.
- the N content is preferably 0.015% or less, and more preferably the N content is 0.012% or less.
- the present invention is a ferritic stainless steel containing the above essential components and the balance being Fe and inevitable impurities. Furthermore, if necessary, one or more selected from Cu, Mo, W and Co, or / and further one selected from V, Nb, Zr, REM, B, Mg and Ca. Alternatively, two or more kinds may be contained within the following range. In addition, since the effects of the present invention are not impaired even if the following elements are contained below the lower limit in the range below, the effect of the present invention is not impaired when the following elements are contained below the lower limit.
- Cu 0.01-1.00%
- Cu is an element that is particularly effective in improving the corrosion resistance of the base material and the welded portion when an aqueous solution or weakly acidic water drops adhere. This effect is obtained when the content is 0.01% or more, and the higher the Cu content, the higher the effect.
- the Cu content is preferably in the range of 0.01 to 1.00%. More preferably, the Cu content is 0.10% or more, and further preferably 0.30% or more. Further, the Cu content is more preferably 0.60% or less, and further preferably 0.45% or less.
- Mo 0.01-2.00% Mo is an element that significantly improves the corrosion resistance of stainless steel. This effect is obtained when the content is 0.01% or more, and the effect is improved as the content is increased. However, if the Mo content exceeds 2.00%, the rolling load at the time of hot rolling increases, the productivity may decrease, and the steel sheet strength may excessively increase. Moreover, since Mo is an expensive element, the inclusion of a large amount increases the manufacturing cost. Therefore, when Mo is contained, the Mo content is preferably 0.01 to 2.00%. More preferably, the Mo content is 0.10% or more, and further preferably 0.30% or more. Further, the Mo content is more preferably 1.40% or less, and further preferably 0.90% or less.
- W 0.01 to 0.20% W has an effect of improving the corrosion resistance similarly to Mo. This effect is obtained by containing 0.01% or more of W. However, if W is contained in excess of 0.20%, the strength is increased and the productivity may be decreased due to an increase in rolling load. Therefore, when W is contained, the W content is preferably in the range of 0.01 to 0.20%. More preferably, the W content is 0.05% or more. Further, more preferably, the W content is 0.15% or less.
- Co 0.01 to 0.20%
- Co is an element that improves toughness. This effect is obtained by containing 0.01% or more of Co. On the other hand, if the Co content exceeds 0.20%, the workability may decrease. Therefore, when Co is contained, the Co content is preferably in the range of 0.01 to 0.20%.
- V 0.01 to 0.20%
- V forms carbonitrides with C and N, suppresses sensitization during welding, and improves the corrosion resistance of the welded portion. This effect is obtained when the V content is 0.01% or more.
- the V content is preferably 0.01 to 0.20%. More preferably, the V content is 0.02% or more. Further, more preferably, the V content is 0.050% or less.
- Nb 0.01 to 0.10%
- Nb has the effect of increasing the 0.2% proof stress by refining the crystal grains and precipitating as fine carbonitrides. These effects are obtained when the Nb content is 0.01% or more.
- Nb also has the effect of raising the recrystallization temperature, and if the Nb content exceeds 0.10%, the annealing temperature necessary for causing sufficient recrystallization in hot-rolled sheet annealing becomes excessively high. Therefore, it may not be possible to obtain a ferrite single-phase structure having an average crystal grain size of 5 to 20 ⁇ m, which is required by the present invention, after annealing a hot rolled sheet. Therefore, when Nb is contained, the Nb content is preferably in the range of 0.01 to 0.10%. More preferably, the Nb content is 0.01 to 0.05%.
- Zr 0.01 to 0.20%
- Zr has the effect of binding to C and N to suppress sensitization. This effect is obtained by containing 0.01% or more of Zr.
- the Zr content is preferably in the range of 0.01 to 0.20%. More preferably, the Zr content is in the range of 0.01 to 0.10%.
- REM 0.001 to 0.100% REM (Rare Earth Metals) has the effect of improving the oxidation resistance, and suppresses the formation of an oxide film (welding temper color) at the welded part to suppress the formation of a Cr-deficient region immediately below the oxide film. This effect is obtained by containing REM in an amount of 0.001% or more. On the other hand, if REM is contained in excess of 0.100%, the hot workability may be deteriorated. Therefore, when REM is contained, the REM content is preferably in the range of 0.001 to 0.100%. More preferably, the REM content is in the range of 0.001 to 0.050%.
- B 0.0002 to 0.0025%
- B is an element effective for improving the secondary working brittleness resistance after deep drawing. This effect is obtained when the B content is 0.0002% or more. On the other hand, if B is contained in excess of 0.0025%, the workability and toughness may decrease. Therefore, when B is contained, the B content is preferably in the range of 0.0002 to 0.0025%. More preferably, the B content is 0.0003% or more. Further, more preferably, the B content is 0.0006% or less.
- Mg 0.0005 to 0.0030%
- Mg is an element effective for improving the equiaxed crystal ratio of the slab and improving the workability and toughness. Further, in the steel containing Ti as in the present invention, when the Ti carbonitride coarsens, the toughness decreases, but Mg also has the effect of suppressing the coarsening of the Ti carbonitride. These effects are obtained by containing 0.0005% or more of Mg. On the other hand, if the Mg content exceeds 0.0030%, the surface properties of steel may be deteriorated. Therefore, when Mg is contained, the Mg content is preferably in the range of 0.0005 to 0.0030%. More preferably, the Mg content is 0.0010% or more. Further, more preferably, the Mg content is 0.0020% or less.
- Ca 0.0003 to 0.0030%
- Ca is an effective component for preventing clogging of the nozzle due to crystallization of Ti-based inclusions that are likely to occur during continuous casting. The effect is obtained by containing 0.0003% or more of Ca.
- the Ca content is preferably in the range of 0.0003 to 0.0030%. More preferably, the Ca content is 0.0005% or more. Further, the Ca content is more preferably 0.0015% or less, and further preferably 0.0010% or less.
- the ferritic stainless steel hot-rolled annealed steel sheet of the present invention uses a steel slab having the above-mentioned composition, and obtains a hot-rolled steel sheet by an ordinary hot rolling, and further 600 ° C or more and less than 750 ° C to the hot-rolled steel sheet. It is obtained by performing hot-rolled sheet annealing for 1 minute to 24 hours.
- molten steel composed of the above-mentioned composition is melted by a known method such as a converter, an electric furnace, a vacuum melting furnace, etc., and made into a steel material (slab) by the continuous casting method or the ingot-casting method.
- the slab is heated at 1050 to 1250 ° C for 1 to 24 hours, or directly subjected to hot rolling as cast before the slab after casting falls below the above temperature range.
- the winding treatment is preferably performed at 550 ° C. or higher.
- Hot-rolled sheet annealing Hold at 600 ° C. or higher and lower than 750 ° C. for 1 minute to 24 hours
- hot-rolled sheet annealing is performed after the hot rolling process is completed.
- the rolling structure formed in the hot rolling process is recrystallized and the martensite phase generated in the hot rolling process is transformed into a ferrite phase without excessively coarsening the metal structure. Let In order to obtain this effect, it is necessary to perform hot-rolled sheet annealing at 600 ° C. or higher and lower than 750 ° C.
- the annealing temperature is less than 600 ° C., recrystallization becomes insufficient, the hot rolled structure becomes fine recovery grains and the metal structure becomes excessively fine, and a predetermined dimensional accuracy cannot be obtained during punching. Further, in the metal structure after hot-rolled sheet annealing, the work structure and martensite phase remain, even if the average crystal grain size is within a predetermined range, punching cracks due to excessive hardening of the steel sheet May occur. On the other hand, when the annealing temperature is 750 ° C. or higher, the crystal grains become excessively coarse and exceed the average crystal grain size of 20 ⁇ m, and a predetermined dimensional accuracy cannot be obtained during punching.
- hot-rolled sheet annealing is performed by holding in the temperature range of 600 ° C or higher and lower than 750 ° C for 1 minute to 24 hours.
- the hot-rolled sheet annealing temperature is 600 ° C or higher, more preferably 640 ° C or higher.
- the hot rolled sheet annealing temperature is 700 ° C. or lower.
- the holding time is preferably 1 hour or longer, more preferably 6 hours or longer. Further, the preferable holding time is 20 hours or less, and more preferably 12 hours or less.
- the method of hot-rolled sheet annealing is not particularly limited, and may be box annealing (batch annealing) or continuous annealing.
- the obtained hot-rolled annealed steel sheet may be subjected to descaling treatment by shot blasting or pickling if necessary. Furthermore, in order to improve the surface texture, grinding or polishing may be performed. Further, the hot rolled annealed steel sheet provided by the present invention may be subjected to cold rolling and cold rolled sheet annealing thereafter.
- Molten stainless steel having the chemical composition shown in Table 1 was melted by a 100 kg vacuum melting furnace. These steel ingots are heated at 1100 ° C. for 1 hour, hot-rolled to the plate thickness shown in Table 2 (see the plate thickness after hot rolling in Table 2), and then held at 650 ° C. for 1 h and then cooled in a furnace. A hot-rolled steel sheet was obtained by performing a winding simulation process. Then, after holding for 8 hours at the temperature shown in Table 2 (refer to the hot-rolled sheet annealing temperature in Table 2), the hot-rolled sheet was annealed to obtain a hot-rolled annealed steel sheet. The plate thickness of each of the obtained hot-rolled annealed steel plates was the same as the hot-rolled finished plate thickness. The hot rolled annealed steel sheet thus obtained was evaluated as follows.
- a test piece for microstructure observation was sampled from the center of the plate width, the cross section in the rolling direction was mirror-polished, and then corroded for observation with an aqueous solution of picric acid-hydrochloric acid to reveal a metal structure, and the magnification was 500 times. It was determined whether the metal structure of each steel sheet was a ferrite single phase structure by distinguishing the ferrite phase and the martensite phase from the morphology of the metal structure by observing with an optical microscope of No. 2. Specifically, a region in which crystal grains are uniform and flat and a relatively bright contrast is exhibited was determined to be a ferrite phase.
- the surface morphology peculiar to the martensite phase such as sub-grain boundaries and block boundaries was observed in the crystal grains, and a region exhibiting a darker contrast than the ferrite phase was determined to be the martensite phase.
- F represents that the metal structure was a ferrite single phase structure.
- the surface of the test piece was photographed after 5 cycles of the salt spray cycle test, the rusted area on the surface of the test piece was measured by image analysis, and the rusted area ratio (( Rust area / total area of test piece) ⁇ 100 [%]) was calculated.
- a rusting area ratio of 10% or less was evaluated as excellent corrosion resistance ( ⁇ ), a value of more than 10% and 25% or less was evaluated as pass ( ⁇ ), and a value of more than 25% was evaluated as unacceptable ( ⁇ ).
- Table 2 shows the test results together with the hot rolled sheet annealing conditions.
- No. 1 in which the steel composition and hot-rolled sheet annealing conditions satisfy the scope of the present invention.
- Nos. 1 to 36 in addition to the formation of an austenite phase during heating in the hot rolling process, recrystallization occurred without causing excessive coarsening of crystal grains by the predetermined hot-rolled sheet annealing, and a predetermined average crystal grain size was obtained.
- a predetermined punching workability was obtained.
- the corrosion resistance of the obtained hot-rolled annealed sheet it was confirmed that the rusting area ratios were all 25% or less, and that they also had sufficient corrosion resistance.
- No. No. 44 is an example in which steel A14 having a predetermined steel composition was annealed at 806 ° C., which exceeds the range of the present invention, and the average grain size was coarsened to 34 ⁇ m, which exceeds the range of the present invention. Although it had a predetermined steel composition, the crystal grains were excessively coarse, so that significant sagging and burrs occurred during the punching process, and the predetermined punching workability was not obtained.
- the ferritic stainless steel hot-rolled and annealed steel sheet obtained in the present invention is particularly suitable for applications requiring high workability and corrosion resistance, for example, flanges having burring portions.
Abstract
The present invention provides: a ferrite stainless hot-rolled-and-annealed steel sheet that is excellent for punching, has substantial corrosion resistance, and makes it possible to achieve a prescribed dimensional precision without cracking when punched into a thick flange; and a production method for the ferrite stainless hot-rolled-and-annealed steel sheet. A ferrite stainless hot-rolled-and-annealed steel sheet that has a ferrite single phase structure that has a component composition that contains, by mass%, 0.001%–0.020% of C, 0.05%–1.00% of Si, 0.05%–1.00% of Mn, no more than 0.04% of P, no more than 0.01% of S, 0.01%–0.10% of Al, 10.0%–20.0% of Cr, 0.50%–2.00% of Ni, 0.10%–0.40% of Ti, and 0.001%–0.020% of N, the remainder being Fe and unavoidable impurities, the average crystal grain size of the metal structure of the ferrite single phase structure being 5–20 µm.
Description
本発明は、フランジ等への適用に好適な加工性に優れたフェライト系ステンレス熱延焼鈍鋼板およびその製造方法に関するものである。
The present invention relates to a hot rolled annealed ferritic stainless steel sheet having excellent workability suitable for application to flanges and the like, and a method for manufacturing the same.
近年、温室効果ガスであるＣＯ２排出量の削減のため、自動車における排気ガスに関する法規制の強化が進んでいる。自動車排気ガスにおけるＣＯ２排出量を削減するためには、燃費の向上が有効であるため、エンジンにおける燃焼温度の高温化に向けた検討が進んでいる。
In recent years, in order to reduce CO 2 emission which is a greenhouse gas, legal regulations concerning exhaust gas in automobiles have been strengthened. In order to reduce the amount of CO 2 emission in automobile exhaust gas, improvement of fuel efficiency is effective, and therefore studies for increasing combustion temperature in an engine are under way.
エンジンで発生した排気ガスは排気ガス再循環（Ｅｘｈａｕｓｔ Ｇａｓ Ｒｅｃｉｒｃｕｌａｔｉｏｎ、ＥＧＲ）システムやマフラー等の排気系部品を介して大気に放出される。このような自動車排気系の各部品は、ガスの漏洩を防ぐためにフランジを介して締結される。排気系部品に適用されるフランジは締結部品として十分な寸法精度を有する必要がある。
Exhaust gas generated by the engine is released to the atmosphere via exhaust gas recirculation (Exhaust Gas Recirculation, EGR) system and exhaust system parts such as muffler. Each component of such an automobile exhaust system is fastened via a flange in order to prevent gas leakage. The flange applied to the exhaust system component needs to have sufficient dimensional accuracy as a fastening component.
従来、このような厚肉のフランジには普通鋼が用いられてきた。しかし近年、自動車のさらなる燃費改善への要求から、エンジン燃焼温度およびエンジンからの排気ガスのさらなる高温化が進んでいる。それに伴ってフランジに従来以上の高温強度と耐食性が求められるようになってきた。このような背景から、近年では普通鋼より高温強度と耐食性に優れるステンレス鋼、特に熱膨張率が比較的小さく熱応力が発生しにくい高強度フェライト系ステンレス鋼板（例えば、ＡＳＴＭ Ａ２４０／２４０Ｍ－Ｓ４０９７５（１１ｍａｓｓ％Ｃｒ－Ｔｉ－Ｎｉ鋼）の板厚の厚いもの（例えば板厚で５ｍｍ以上）の適用が進んでいる。
Conventionally, ordinary steel has been used for such thick flanges. However, in recent years, the combustion temperature of the engine and the exhaust gas from the engine have been further increased due to the demand for further improvement in fuel consumption of automobiles. Along with that, flanges are required to have higher high-temperature strength and corrosion resistance than ever before. Against this background, in recent years, stainless steel is superior to ordinary steel in high-temperature strength and corrosion resistance, especially high-strength ferritic stainless steel sheet with a relatively small coefficient of thermal expansion and in which thermal stress is unlikely to occur (for example, ASTM A240 / 240M-S40975 ( 11 mass% Cr-Ti-Ni steel having a large plate thickness (for example, a plate thickness of 5 mm or more) is being applied.
しかし、排気系に使用されるフランジは板厚が厚いため（５ｍｍ以上が多い）、フランジを製造する際の打ち抜き加工時に割れが生じて、フランジ部品を適正に製造できない場合があるという課題があり、打ち抜き加工性に優れた厚肉のフェライト系ステンレス鋼板が強く求められている。
However, since the flange used for the exhaust system has a large plate thickness (often 5 mm or more), there is a problem that the flange part may not be manufactured properly due to cracking during punching during manufacturing the flange. There is a strong demand for thick-walled ferritic stainless steel sheets with excellent punching workability.
このような市場要求に対し、例えば、特許文献１には、質量％で、Ｃ：０．０１５％以下、Ｓｉ：０．０１～０．４％、Ｍｎ：０．０１～０．８％、Ｐ：０．０４％以下、Ｓ：０．０１％以下、Ｃｒ：１４．０～１８．０％未満、Ｎｉ：０．０５～１％、Ｎｂ：０．３～０．６％、Ｔｉ：０．０５％以下、Ｎ：０．０２０％以下、Ａｌ：０．１０％以下、Ｂ：０．０００２～０．００２０％を含有し、残部がＦｅ及び不可避的不純物であり、Ｎｂ、ＣおよびＮの含有量がＮｂ／（Ｃ＋Ｎ）≧１６を満たし、０℃におけるシャルピー衝撃値が１０Ｊ／ｃｍ２以上であり、板厚が５．０～９．０ｍｍであるフェライト系ステンレス熱延鋼板が開示されている。
In order to meet such market demand, for example, in Patent Document 1, in mass%, C: 0.015% or less, Si: 0.01 to 0.4%, Mn: 0.01 to 0.8%, P: 0.04% or less, S: 0.01% or less, Cr: 14.0 to less than 18.0%, Ni: 0.05 to 1%, Nb: 0.3 to 0.6%, Ti: 0.05% or less, N: 0.020% or less, Al: 0.10% or less, B: 0.0002 to 0.0020%, the balance being Fe and unavoidable impurities, and Nb, C and Disclosed is a ferritic stainless hot rolled steel sheet having a N content satisfying Nb / (C + N) ≧ 16, a Charpy impact value at 0 ° C. of 10 J / cm 2 or more, and a sheet thickness of 5.0 to 9.0 mm. Has been done.
本発明者らは特許文献１に開示された手法を用いて、ＡＳＴＭ Ａ２４０／２４０Ｍ－Ｓ４０９７５に準拠する鋼成分を有する板厚１０ｍｍのフェライト系ステンレス鋼板を試作し、２０ｍｍφの孔を有するフランジを、クリアランス１０％の打ち抜き加工により作製した。その結果、いずれも打ち抜きによる割れは生じなかったものの、フランジの外周寸法および／または中心の孔寸法が部品の許容公差を超える場合があり、厚肉のフランジに適用するには十分ではないことが明らかとなった。
The inventors of the present invention prototyped a ferritic stainless steel plate having a plate thickness of 10 mm having a steel component conforming to ASTM A240 / 240M-S40975 by using the method disclosed in Patent Document 1, and provided a flange having a 20 mmφ hole with a flange. It was manufactured by punching with a clearance of 10%. As a result, none of the cracks due to punching occurred, but the outer peripheral dimension and / or the central hole dimension of the flange may exceed the allowable tolerance of the part, and it may not be sufficient to apply to thick flanges. It became clear.
本発明は、かかる課題を解決し、十分な耐食性を有するとともに、厚肉のフランジへの打ち抜き加工時に割れが生じることなく所定の寸法精度を得られる、優れた打ち抜き加工性を有するフェライト系ステンレス熱延焼鈍鋼板およびその製造方法を提供することを目的とする。
The present invention solves the above problems, has sufficient corrosion resistance, and can obtain a predetermined dimensional accuracy without cracking during punching into a thick flange, and a ferritic stainless steel with excellent punching workability. An object of the present invention is to provide annealed steel sheet and a manufacturing method thereof.
本発明者らは、上記課題を解決するために詳細な検討を行った。その結果、打ち抜き加工において割れが発生することなく所定の寸法精度を得るためには、鋼板の金属組織をフェライト単相組織とし、かつその平均結晶粒径を５～２０μｍの範囲に制御すればよいことを知見した。
The present inventors conducted a detailed study to solve the above problems. As a result, in order to obtain a predetermined dimensional accuracy without cracking during punching, the steel sheet should have a ferrite single-phase structure and its average crystal grain size should be controlled within the range of 5 to 20 μm. I found out that.
そして、適切な成分のフェライト系ステンレス鋼に対して熱間圧延を行い、得られた熱延鋼板に対して、フェライト単相域となる適切な条件、具体的には６００℃以上７５０℃未満で１分～２４時間保持する熱延板焼鈍を行うことにより、金属組織をフェライト単相であり、かつ平均結晶粒径が５～２０μｍの範囲に制御できることを知見した。
Then, hot rolling is performed on a ferritic stainless steel having an appropriate component, and the obtained hot rolled steel sheet is subjected to appropriate conditions to be a ferrite single phase region, specifically, 600 ° C or higher and lower than 750 ° C. It has been found that by performing hot-rolled sheet annealing for 1 minute to 24 hours, the metal structure can be controlled to a ferrite single phase and the average crystal grain size can be controlled to the range of 5 to 20 μm.
本発明は以上の知見に基づいてなされたものであり、以下を要旨とするものである。
［１］質量％で、Ｃ：０．００１～０．０２０％、Ｓｉ：０．０５～１．００％、Ｍｎ：０．０５～１．００％、Ｐ：０．０４％以下、Ｓ：０．０１％以下、Ａｌ：０．０１～０．１０％、Ｃｒ：１０．０～２０．０％、Ｎｉ：０．５０～２．００％、Ｔｉ：０．１０～０．４０％、Ｎ：０．００１～０．０２０％を含有し、残部がＦｅおよび不可避的不純物からなる成分組成を有し、金属組織が平均結晶粒径５～２０μｍのフェライト単相組織であるフェライト系ステンレス熱延焼鈍鋼板。
［２］質量％で、さらに、Ｃｕ：０．０１～１．００％、Ｍｏ：０．０１～２．００％、Ｗ：０．０１～０．２０％、Ｃｏ：０．０１～０．２０％のうちから選ばれる１種または２種以上を含有する前記［１］に記載のフェライト系ステンレス熱延焼鈍鋼板。
［３］質量％で、さらに、Ｖ：０．０１～０．２０％、Ｎｂ：０．０１～０．１０％、Ｚｒ：０．０１～０．２０％、ＲＥＭ：０．００１～０．１００％、Ｂ：０．０００２～０．００２５％、Ｍｇ：０．０００５～０．００３０％、Ｃａ：０．０００３～０．００３０％のうちから選ばれる１種または２種以上を含有する前記［１］または［２］に記載のフェライト系ステンレス熱延焼鈍鋼板。
［４］前記［１］～［３］のいずれかに記載のフェライト系ステンレス熱延焼鈍鋼板の製造方法であって、熱間圧延工程で得られた熱延鋼板について６００℃以上７５０℃未満で１分～２４時間保持する熱延板焼鈍を行うフェライト系ステンレス熱延焼鈍鋼板の製造方法。 The present invention has been made based on the above findings, and has the following gist.
[1]% by mass, C: 0.001 to 0.020%, Si: 0.05 to 1.00%, Mn: 0.05 to 1.00%, P: 0.04% or less, S: 0.01% or less, Al: 0.01 to 0.10%, Cr: 10.0 to 20.0%, Ni: 0.50 to 2.00%, Ti: 0.10 to 0.40%, N: 0.001 to 0.020%, a balance of Fe and unavoidable impurities in the balance, and a ferritic stainless steel with a metallic structure of a ferrite single-phase structure with an average crystal grain size of 5 to 20 μm. Annealed steel sheet.
[2] In% by mass, further, Cu: 0.01 to 1.00%, Mo: 0.01 to 2.00%, W: 0.01 to 0.20%, Co: 0.01 to 0. The ferritic stainless steel hot rolled annealed steel sheet according to the above [1], containing one or more selected from 20%.
[3]% by mass, V: 0.01 to 0.20%, Nb: 0.01 to 0.10%, Zr: 0.01 to 0.20%, REM: 0.001 to 0. 100%, B: 0.0002 to 0.0025%, Mg: 0.0005 to 0.0030%, Ca: 0.0003 to 0.0030%, and one or more selected from the above. The ferritic stainless steel hot rolled annealed steel sheet according to [1] or [2].
[4] The method for producing a ferritic stainless steel hot rolled annealed steel sheet according to any one of [1] to [3] above, wherein the hot rolled steel sheet obtained in the hot rolling step is at 600 ° C or higher and lower than 750 ° C. A method for producing a ferritic stainless steel hot-rolled annealed steel sheet, which comprises performing hot-rolled sheet annealing for 1 minute to 24 hours.
［１］質量％で、Ｃ：０．００１～０．０２０％、Ｓｉ：０．０５～１．００％、Ｍｎ：０．０５～１．００％、Ｐ：０．０４％以下、Ｓ：０．０１％以下、Ａｌ：０．０１～０．１０％、Ｃｒ：１０．０～２０．０％、Ｎｉ：０．５０～２．００％、Ｔｉ：０．１０～０．４０％、Ｎ：０．００１～０．０２０％を含有し、残部がＦｅおよび不可避的不純物からなる成分組成を有し、金属組織が平均結晶粒径５～２０μｍのフェライト単相組織であるフェライト系ステンレス熱延焼鈍鋼板。
［２］質量％で、さらに、Ｃｕ：０．０１～１．００％、Ｍｏ：０．０１～２．００％、Ｗ：０．０１～０．２０％、Ｃｏ：０．０１～０．２０％のうちから選ばれる１種または２種以上を含有する前記［１］に記載のフェライト系ステンレス熱延焼鈍鋼板。
［３］質量％で、さらに、Ｖ：０．０１～０．２０％、Ｎｂ：０．０１～０．１０％、Ｚｒ：０．０１～０．２０％、ＲＥＭ：０．００１～０．１００％、Ｂ：０．０００２～０．００２５％、Ｍｇ：０．０００５～０．００３０％、Ｃａ：０．０００３～０．００３０％のうちから選ばれる１種または２種以上を含有する前記［１］または［２］に記載のフェライト系ステンレス熱延焼鈍鋼板。
［４］前記［１］～［３］のいずれかに記載のフェライト系ステンレス熱延焼鈍鋼板の製造方法であって、熱間圧延工程で得られた熱延鋼板について６００℃以上７５０℃未満で１分～２４時間保持する熱延板焼鈍を行うフェライト系ステンレス熱延焼鈍鋼板の製造方法。 The present invention has been made based on the above findings, and has the following gist.
[1]% by mass, C: 0.001 to 0.020%, Si: 0.05 to 1.00%, Mn: 0.05 to 1.00%, P: 0.04% or less, S: 0.01% or less, Al: 0.01 to 0.10%, Cr: 10.0 to 20.0%, Ni: 0.50 to 2.00%, Ti: 0.10 to 0.40%, N: 0.001 to 0.020%, a balance of Fe and unavoidable impurities in the balance, and a ferritic stainless steel with a metallic structure of a ferrite single-phase structure with an average crystal grain size of 5 to 20 μm. Annealed steel sheet.
[2] In% by mass, further, Cu: 0.01 to 1.00%, Mo: 0.01 to 2.00%, W: 0.01 to 0.20%, Co: 0.01 to 0. The ferritic stainless steel hot rolled annealed steel sheet according to the above [1], containing one or more selected from 20%.
[3]% by mass, V: 0.01 to 0.20%, Nb: 0.01 to 0.10%, Zr: 0.01 to 0.20%, REM: 0.001 to 0. 100%, B: 0.0002 to 0.0025%, Mg: 0.0005 to 0.0030%, Ca: 0.0003 to 0.0030%, and one or more selected from the above. The ferritic stainless steel hot rolled annealed steel sheet according to [1] or [2].
[4] The method for producing a ferritic stainless steel hot rolled annealed steel sheet according to any one of [1] to [3] above, wherein the hot rolled steel sheet obtained in the hot rolling step is at 600 ° C or higher and lower than 750 ° C. A method for producing a ferritic stainless steel hot-rolled annealed steel sheet, which comprises performing hot-rolled sheet annealing for 1 minute to 24 hours.
本発明によれば、十分な耐食性を有するとともに、優れた打ち抜き加工性を有するフェライト系ステンレス熱延焼鈍鋼板が得られる。
According to the present invention, it is possible to obtain a ferritic stainless steel hot-rolled annealed steel sheet having sufficient corrosion resistance and excellent punching workability.
なお、本発明における十分な耐食性とは、表面を＃６００エメリーペーパーにより研磨仕上げした後に端面部をシールした鋼板にＪＩＳ Ｈ ８５０２に規定された塩水噴霧サイクル試験（塩水噴霧（５質量％ＮａＣｌ、３５℃、噴霧２ｈｒ）→乾燥（６０℃、４ｈｒ、相対湿度４０％）→湿潤（５０℃、２ｈｒ、相対湿度≧９５％））を１サイクルとする試験）を５サイクル行った場合の鋼板表面における発錆面積率（＝発錆面積／鋼板全面積×１００［％］）が２５％以下であることを意味する。
Sufficient corrosion resistance in the present invention means a salt water spray cycle test (salt water spray (5 mass% NaCl, 35% by mass, 35% by mass NaCl, 35% by weight) on a steel plate whose end surface is sealed after polishing the surface with # 600 emery paper. C., spray 2 hr) → dry (60 ° C., 4 hr, relative humidity 40%) → wet (50 ° C., 2 hr, relative humidity ≧ 95%)) This means that the rusted area ratio (= rusted area / total steel plate area × 100 [%]) is 25% or less.
また、打ち抜き加工性の評価としては、まず、熱延焼鈍鋼板から１００ｍｍ×１００ｍｍの試験片を採取した後、該試験片中央部にφ２０ｍｍ（公差±０．１ｍｍ）の孔が形成されるように、直径２０ｍｍの肉抜き用円柱刃を有する上金型（ポンチ）と直径２０ｍｍ以上の孔を有する下金型（ダイス）を設置したクランクプレス機によって、打ち抜き加工により５枚の試験片を作製する。なお、打ち抜き加工は上金型と下金型のクリアランスが１０％となるように、下金型側の孔直径を試験片板厚に合せて選定することにより行う。ここで、上記のクリアランス（Ｃ）［％］、ダイスの孔の直径（ダイスの内径）（Ｄｄ）［ｍｍ］及びポンチの直径（Ｄｐ）［ｍｍ］は、板厚（ｔ）［ｍｍ］も含め、以下の式（１）の関係で表される。
Ｃ＝（Ｄｄ－Ｄｐ）÷（２×ｔ）×１００・・・式（１）
本発明における優れた打ち抜き加工性とは、このようにして得られた試験片について、試験片外観の目視観察と試験片中央部の孔径をデジタルノギスにより測定した場合、割れがなく、打ち抜き加工後の孔径が５枚の試験片すべてで１９．９～２０．１ｍｍの範囲となることを意味する。 In order to evaluate the punching workability, first, a 100 mm × 100 mm test piece was sampled from a hot-rolled annealed steel sheet, and a hole of φ20 mm (tolerance ± 0.1 mm) was formed in the center of the test piece. By a crank press equipped with an upper die (punch) having a 20 mm diameter columnar cutting blade and a lower die (die) having holes with a diameter of 20 mm or more, five test pieces are prepared by punching. . The punching process is performed by selecting the hole diameter on the lower mold side in accordance with the thickness of the test piece plate so that the clearance between the upper mold and the lower mold is 10%. Here, the clearance (C) [%], the diameter of the hole of the die (the inner diameter of the die) (Dd) [mm] and the diameter of the punch (Dp) [mm] are also the plate thickness (t) [mm]. Including, it is expressed by the following equation (1).
C = (Dd−Dp) ÷ (2 × t) × 100 ... Equation (1)
The excellent punching workability in the present invention, for the test piece thus obtained, when visually observing the appearance of the test piece and measuring the hole diameter of the center part of the test piece with a digital caliper, there is no crack, and after punching work It means that the pore size of all the five test pieces is in the range of 19.9 to 20.1 mm.
Ｃ＝（Ｄｄ－Ｄｐ）÷（２×ｔ）×１００・・・式（１）
本発明における優れた打ち抜き加工性とは、このようにして得られた試験片について、試験片外観の目視観察と試験片中央部の孔径をデジタルノギスにより測定した場合、割れがなく、打ち抜き加工後の孔径が５枚の試験片すべてで１９．９～２０．１ｍｍの範囲となることを意味する。 In order to evaluate the punching workability, first, a 100 mm × 100 mm test piece was sampled from a hot-rolled annealed steel sheet, and a hole of φ20 mm (tolerance ± 0.1 mm) was formed in the center of the test piece. By a crank press equipped with an upper die (punch) having a 20 mm diameter columnar cutting blade and a lower die (die) having holes with a diameter of 20 mm or more, five test pieces are prepared by punching. . The punching process is performed by selecting the hole diameter on the lower mold side in accordance with the thickness of the test piece plate so that the clearance between the upper mold and the lower mold is 10%. Here, the clearance (C) [%], the diameter of the hole of the die (the inner diameter of the die) (Dd) [mm] and the diameter of the punch (Dp) [mm] are also the plate thickness (t) [mm]. Including, it is expressed by the following equation (1).
C = (Dd−Dp) ÷ (2 × t) × 100 ... Equation (1)
The excellent punching workability in the present invention, for the test piece thus obtained, when visually observing the appearance of the test piece and measuring the hole diameter of the center part of the test piece with a digital caliper, there is no crack, and after punching work It means that the pore size of all the five test pieces is in the range of 19.9 to 20.1 mm.
以下、本発明の実施形態について説明する。
An embodiment of the present invention will be described below.
本発明のフェライト系ステンレス熱延焼鈍鋼板は、質量％で、Ｃ：０．００１～０．０２０％、Ｓｉ：０．０５～１．００％、Ｍｎ：０．０５～１．００％、Ｐ：０．０４％以下、Ｓ：０．０１％以下、Ａｌ：０．０１～０．１０％、Ｃｒ：１０．０～２０．０％、Ｎｉ：０．５０～２．００％、Ｔｉ：０．１０～０．４０％、Ｎ：０．００１～０．０２０％を含有し、残部がＦｅおよび不可避的不純物からなる成分組成を有し、金属組織が平均結晶粒径で５～２０μｍのフェライト単相組織であるフェライト系ステンレス熱延焼鈍鋼板である。
The ferritic stainless steel hot rolled annealed steel sheet of the present invention, in mass%, is C: 0.001 to 0.020%, Si: 0.05 to 1.00%, Mn: 0.05 to 1.00%, P : 0.04% or less, S: 0.01% or less, Al: 0.01 to 0.10%, Cr: 10.0 to 20.0%, Ni: 0.50 to 2.00%, Ti: 0.10 to 0.40%, N: 0.001 to 0.020%, with the balance being Fe and inevitable impurities, and having a metal structure of 5 to 20 μm in average crystal grain size. It is a ferritic stainless steel hot-rolled and annealed steel sheet having a ferrite single-phase structure.
以下、本発明を詳細に説明する。
The present invention will be described in detail below.
本発明者らは、ＡＳＴＭ Ａ２４０／２４０Ｍ－Ｓ４０９７５（成分組成は、質量％で、Ｃ≦０．０３％、Ｓｉ≦１．００％、Ｍｎ≦１．００％、Ｐ≦０．０４０％、Ｓ≦０．０３０％、Ｃｒ：１０．５～１１．７％、Ｎｉ：０．５０～１．００％、Ｎ≦０．０３％、Ｔｉ：６×（Ｃ＋Ｎ）～０．７４％を含有し、残部Ｆｅおよび不可避的不純物からなる。）に準拠する板厚１０ｍｍの各種フェライト系ステンレス鋼板を用いて２０ｍｍφの孔を有するフランジを、クリアランス１０％の打ち抜き加工により作製した。その結果、いずれも打ち抜きによる割れは生じなかったものの、フランジの外周寸法および／または中心の孔寸法が部品の許容公差を超える場合があることを知見した。
The present inventors have found that ASTM A240 / 240M-S40975 (the composition of components is% by mass, C ≦ 0.03%, Si ≦ 1.00%, Mn ≦ 1.00%, P ≦ 0.040%, S ≦ 0.030%, Cr: 10.5 to 11.7%, Ni: 0.50 to 1.00%, N ≦ 0.03%, Ti: 6 × (C + N) to 0.74% , The balance Fe and unavoidable impurities.) Using various ferritic stainless steel plates with a plate thickness of 10 mm, a flange having a hole of 20 mmφ was punched with a clearance of 10%. As a result, it was found that the cracks due to punching did not occur in either case, but the outer peripheral dimension of the flange and / or the central hole dimension may exceed the allowable tolerance of the component.
さらに本発明者らは、打ち抜き加工における寸法精度が鋼板によって大きく異なった原因について詳細に検討した。その結果、打ち抜き加工に供した鋼板の平均結晶粒径が５μｍ未満であった場合には打ち抜き加工後の部品寸法が許容公差よりも小さくなること、および鋼板の平均結晶粒径が２０μｍ超であった場合には打ち抜き加工後の部品寸法が許容公差よりも大きくなる傾向にあることを知見した。このことから、本発明者らは打ち抜き加工において十分な寸法精度が安定して得られない原因は、平均結晶粒径が過度に小さい場合には、鋼板が過度に硬質であるために打ち抜き加工時のせん断面比率が小さくなること、および平均結晶粒径が過度に大きい場合には打ち抜き加工時に大きなダレあるいはバリが生じることに起因することを突き止めた。
Furthermore, the present inventors examined in detail the cause that the dimensional accuracy in punching greatly differs depending on the steel sheet. As a result, when the average grain size of the steel sheet subjected to punching was less than 5 μm, the dimension of the part after punching was smaller than the allowable tolerance, and the average grain size of the steel sheet was more than 20 μm. It was found that in the case of punching, the part size after punching tends to be larger than the allowable tolerance. From this, the present inventors can not stably obtain sufficient dimensional accuracy in the punching process, when the average crystal grain size is too small, the steel plate is too hard during the punching process. It was found that this is due to the fact that the shear surface ratio of No. 2 was small, and that when the average crystal grain size was excessively large, large sagging or burrs occurred during punching.
そこで本発明者らは、金属組織が平均結晶粒径で５～２０μｍのフェライト単相組織となるフェライト系ステンレス鋼板を得る手法について、鋼成分、熱間圧延手法ならびに熱延板焼鈍手法の観点で鋭意検討した。その結果、鋼成分、特にＣｒとＮｉの含有量を適切な範囲に制御して熱間圧延工程においてオーステナイト相とフェライト相を生成させた上で熱間圧延を行った後、フェライト単相温度域の適正な温度範囲で熱延板焼鈍を行うことが有効であることを知見した。
Therefore, the inventors of the present invention have a method of obtaining a ferritic stainless steel sheet having a ferrite single-phase structure having an average crystal grain size of 5 to 20 μm in terms of steel composition, hot rolling method and hot rolled sheet annealing method. Diligently studied. As a result, the steel components, especially Cr and Ni contents were controlled in an appropriate range to generate an austenite phase and a ferrite phase in the hot rolling step, and then hot rolling was performed, followed by the ferrite single phase temperature range. It was found that it is effective to carry out hot-rolled sheet annealing in the appropriate temperature range.
次いで、熱延板焼鈍工程をフェライト単相温度域の適正な温度範囲、具体的には６００℃以上７５０℃未満で１分～２４時間保持することにより行う。これにより、熱間圧延後の金属組織に存在していた、フェライト相の再結晶と、マルテンサイト相のフェライト相への変態を生じさせて、フェライト単相組織を得る。この時、熱延板焼鈍温度を６００℃未満とした場合には、フェライト相の再結晶ならびにマルテンサイト相のフェライト相への変態が不十分となり、鋼板の過度な硬質化に起因した打ち抜き割れが生じやすくなる。一方、焼鈍温度が７５０℃以上になると、結晶粒が過度に粗大化して平均結晶粒径が２０μｍを上回って、打ち抜き加工時に大きなダレやバリが発生しやすくなり、打ち抜き加工時に所定の寸法精度が得られない。保持時間を１分未満とした場合、フェライト相の再結晶ならびにマルテンサイト相のフェライト相への変態が不十分となり、鋼板の過度な硬質化に起因した打ち抜き割れが生じやすくなる。保持時間が２４時間を超えると、結晶粒が過度に粗大化して平均結晶粒径が２０μｍを上回り、打ち抜き加工時に大きなダレやバリが発生しやすくなることにより、打ち抜き加工時に所定の寸法精度が得られない。そのため、本発明では６００℃以上７５０℃未満の温度範囲で１分～２４時間保持する熱延板焼鈍を行う必要がある。
Next, the hot-rolled sheet annealing process is performed by holding the ferrite single-phase temperature range in an appropriate temperature range, specifically, 600 ° C or higher and lower than 750 ° C for 1 minute to 24 hours. As a result, recrystallization of the ferrite phase existing in the metal structure after hot rolling and transformation of the martensite phase into the ferrite phase are caused to obtain a ferrite single phase structure. At this time, when the hot-rolled sheet annealing temperature is less than 600 ° C., recrystallization of the ferrite phase and transformation of the martensite phase into the ferrite phase become insufficient, and punching cracks due to excessive hardening of the steel sheet occur. It tends to occur. On the other hand, when the annealing temperature is 750 ° C. or higher, the crystal grains become excessively coarse and the average crystal grain size exceeds 20 μm, and large sagging or burrs are likely to occur during the punching process, and the predetermined dimensional accuracy during the punching process is not achieved. I can't get it. If the holding time is less than 1 minute, recrystallization of the ferrite phase and transformation of the martensite phase to the ferrite phase become insufficient, and punching cracks due to excessive hardening of the steel sheet are likely to occur. If the holding time exceeds 24 hours, the crystal grains become excessively coarse and the average crystal grain size exceeds 20 μm, and large sagging or burrs are likely to occur during punching, so that the prescribed dimensional accuracy can be obtained during punching. I can't. Therefore, in the present invention, it is necessary to perform hot rolled sheet annealing in the temperature range of 600 ° C. or higher and lower than 750 ° C. for 1 minute to 24 hours.
このように、本発明では、金属組織がフェライト単相組織であり、該フェライト単相組織の平均結晶粒径を５～２０μｍとする。好ましくは、この平均結晶粒径は７μｍ以上であり、より好ましくは、１０μｍ以上であえる。また、好ましくは、この平均結晶粒径は１８μｍ以下であり、より好ましくは、１５μｍ以下である。
As described above, in the present invention, the metal structure is a ferrite single-phase structure, and the average crystal grain size of the ferrite single-phase structure is 5 to 20 μm. Preferably, the average crystal grain size is 7 μm or more, and more preferably 10 μm or more. The average crystal grain size is preferably 18 μm or less, more preferably 15 μm or less.
また、平均結晶粒径については、板幅中央部から組織観察用試験片を採取し、圧延方向断面を鏡面研磨後、ＳＥＭ／ＥＢＳＤ法を用いて全厚を含む視野で測定および解析を行い、方位差１５°以上の境界を粒界と定義しＡｒｅａ法に基づいて求めることができる。
Regarding the average crystal grain size, a test piece for observing a structure is taken from the center of the plate width, the cross section in the rolling direction is mirror-polished, and then measured and analyzed in the visual field including the total thickness by using the SEM / EBSD method, A boundary having an orientation difference of 15 ° or more can be defined as a grain boundary and can be obtained based on the Area method.
なお、本発明のフェライト系ステンレス熱延焼鈍鋼板の板厚は特に限定されないが、厚肉のフランジに適用できる板厚であることが望ましいため、５．０ｍｍ以上とすることが好ましく、より好ましくは、８．０ｍｍ以上である。また、板厚は１５．０ｍｍ以下とすることが好ましく、より好ましくは、１３．０ｍｍ以下である。
The plate thickness of the ferritic stainless steel hot-rolled annealed steel sheet of the present invention is not particularly limited, but is preferably a plate thickness applicable to a thick flange, and is preferably 5.0 mm or more, more preferably , 8.0 mm or more. The plate thickness is preferably 15.0 mm or less, more preferably 13.0 mm or less.
次に、本発明のフェライト系ステンレス熱延焼鈍鋼板の成分組成について説明する。
以下、特に断らない限り、成分の含有量の単位である「％」は「質量％」を意味する。 Next, the composition of the ferritic stainless steel hot rolled annealed steel sheet of the present invention will be described.
Hereinafter, unless otherwise specified, “%”, which is a unit of the content of components, means “mass%”.
以下、特に断らない限り、成分の含有量の単位である「％」は「質量％」を意味する。 Next, the composition of the ferritic stainless steel hot rolled annealed steel sheet of the present invention will be described.
Hereinafter, unless otherwise specified, “%”, which is a unit of the content of components, means “mass%”.
Ｃ：０．００１～０．０２０％
Ｃを０．０２０％超えて含有すると、加工性の低下および溶接部の耐食性低下が顕著になる。Ｃ含有量が少ないほど耐食性および加工性の観点では好ましいが、Ｃ含有量を０．００１％未満にするためには精錬に時間がかかり製造上好ましくない。そのため、Ｃ含有量は０．００１～０．０２０％の範囲とする。好ましくは、Ｃ含有量は０．００３％以上であり、さらに好ましくは０．００４％以上である。また、好ましくは、Ｃ含有量は０．０１５％以下であり、さらに好ましくは、０．０１２％以下である。 C: 0.001 to 0.020%
If the content of C exceeds 0.020%, the workability and the corrosion resistance of the welded part are significantly reduced. The smaller the C content is, the more preferable it is from the viewpoint of corrosion resistance and workability. However, if the C content is less than 0.001%, refining takes time, which is not preferable in terms of production. Therefore, the C content is set to the range of 0.001 to 0.020%. Preferably, the C content is 0.003% or more, more preferably 0.004% or more. Further, the C content is preferably 0.015% or less, and more preferably 0.012% or less.
Ｃを０．０２０％超えて含有すると、加工性の低下および溶接部の耐食性低下が顕著になる。Ｃ含有量が少ないほど耐食性および加工性の観点では好ましいが、Ｃ含有量を０．００１％未満にするためには精錬に時間がかかり製造上好ましくない。そのため、Ｃ含有量は０．００１～０．０２０％の範囲とする。好ましくは、Ｃ含有量は０．００３％以上であり、さらに好ましくは０．００４％以上である。また、好ましくは、Ｃ含有量は０．０１５％以下であり、さらに好ましくは、０．０１２％以下である。 C: 0.001 to 0.020%
If the content of C exceeds 0.020%, the workability and the corrosion resistance of the welded part are significantly reduced. The smaller the C content is, the more preferable it is from the viewpoint of corrosion resistance and workability. However, if the C content is less than 0.001%, refining takes time, which is not preferable in terms of production. Therefore, the C content is set to the range of 0.001 to 0.020%. Preferably, the C content is 0.003% or more, more preferably 0.004% or more. Further, the C content is preferably 0.015% or less, and more preferably 0.012% or less.
Ｓｉ：０．０５～１．００％
Ｓｉは、溶接時に形成される酸化皮膜に濃縮して溶接部の耐食性を向上させる効果があるとともに、製鋼工程における脱酸元素としても有用な元素である。これらの効果は０．０５％以上のＳｉの含有により得られ、含有量が多いほどその効果は大きくなる。しかし、１．００％を超えてＳｉを含有すると、熱間圧延工程における圧延荷重の増大や顕著なスケールの生成が生じて、表面欠陥の増加や製造コストの上昇を誘引するため好ましくない。そのため、Ｓｉ含有量は０．０５～１．００％とする。好ましくは、Ｓｉ含有量は０．１０％以上であり、さらに好ましくは０．１５％以上である。また、好ましくは、Ｓｉ含有量は０．６０％以下であり、さらに好ましくは、０．４０％以下である。 Si: 0.05-1.00%
Si has the effect of concentrating in the oxide film formed during welding to improve the corrosion resistance of the welded portion, and is also a useful element as a deoxidizing element in the steelmaking process. These effects are obtained by containing 0.05% or more of Si, and the larger the content, the greater the effects. However, if Si is contained in excess of 1.00%, the rolling load in the hot rolling step increases and a remarkable scale is generated, which causes an increase in surface defects and an increase in manufacturing cost, which is not preferable. Therefore, the Si content is set to 0.05 to 1.00%. The Si content is preferably 0.10% or more, more preferably 0.15% or more. Further, the Si content is preferably 0.60% or less, and more preferably 0.40% or less.
Ｓｉは、溶接時に形成される酸化皮膜に濃縮して溶接部の耐食性を向上させる効果があるとともに、製鋼工程における脱酸元素としても有用な元素である。これらの効果は０．０５％以上のＳｉの含有により得られ、含有量が多いほどその効果は大きくなる。しかし、１．００％を超えてＳｉを含有すると、熱間圧延工程における圧延荷重の増大や顕著なスケールの生成が生じて、表面欠陥の増加や製造コストの上昇を誘引するため好ましくない。そのため、Ｓｉ含有量は０．０５～１．００％とする。好ましくは、Ｓｉ含有量は０．１０％以上であり、さらに好ましくは０．１５％以上である。また、好ましくは、Ｓｉ含有量は０．６０％以下であり、さらに好ましくは、０．４０％以下である。 Si: 0.05-1.00%
Si has the effect of concentrating in the oxide film formed during welding to improve the corrosion resistance of the welded portion, and is also a useful element as a deoxidizing element in the steelmaking process. These effects are obtained by containing 0.05% or more of Si, and the larger the content, the greater the effects. However, if Si is contained in excess of 1.00%, the rolling load in the hot rolling step increases and a remarkable scale is generated, which causes an increase in surface defects and an increase in manufacturing cost, which is not preferable. Therefore, the Si content is set to 0.05 to 1.00%. The Si content is preferably 0.10% or more, more preferably 0.15% or more. Further, the Si content is preferably 0.60% or less, and more preferably 0.40% or less.
Ｍｎ：０．０５～１．００％
Ｍｎはオーステナイト生成元素であり、熱間圧延工程における圧延加工前の加熱時に生成するオーステナイト量を増加させる効果がある。また、脱酸剤としての作用もある。その効果を得るためには０．０５％以上のＭｎの含有が必要である。しかし、Ｍｎ含有量が１．００％を超えると、腐食の起点となるＭｎＳの析出が促進され、耐食性が低下する。そのため、Ｍｎ含有量は０．０５～１．００％とする。好ましくは、Ｍｎ含有量は０．１０％以上であり、さらに好ましくは０．１５％以上である。また、好ましくは、Ｍｎ含有量は０．６０％以下であり、さらに好ましくは、０．３０％以下である。 Mn: 0.05-1.00%
Mn is an austenite forming element, and has an effect of increasing the amount of austenite generated during heating before rolling in the hot rolling step. It also acts as a deoxidizer. In order to obtain the effect, it is necessary to contain 0.05% or more of Mn. However, if the Mn content exceeds 1.00%, the precipitation of MnS, which is the starting point of corrosion, is promoted, and the corrosion resistance decreases. Therefore, the Mn content is set to 0.05 to 1.00%. Preferably, the Mn content is 0.10% or more, more preferably 0.15% or more. Further, the Mn content is preferably 0.60% or less, and more preferably 0.30% or less.
Ｍｎはオーステナイト生成元素であり、熱間圧延工程における圧延加工前の加熱時に生成するオーステナイト量を増加させる効果がある。また、脱酸剤としての作用もある。その効果を得るためには０．０５％以上のＭｎの含有が必要である。しかし、Ｍｎ含有量が１．００％を超えると、腐食の起点となるＭｎＳの析出が促進され、耐食性が低下する。そのため、Ｍｎ含有量は０．０５～１．００％とする。好ましくは、Ｍｎ含有量は０．１０％以上であり、さらに好ましくは０．１５％以上である。また、好ましくは、Ｍｎ含有量は０．６０％以下であり、さらに好ましくは、０．３０％以下である。 Mn: 0.05-1.00%
Mn is an austenite forming element, and has an effect of increasing the amount of austenite generated during heating before rolling in the hot rolling step. It also acts as a deoxidizer. In order to obtain the effect, it is necessary to contain 0.05% or more of Mn. However, if the Mn content exceeds 1.00%, the precipitation of MnS, which is the starting point of corrosion, is promoted, and the corrosion resistance decreases. Therefore, the Mn content is set to 0.05 to 1.00%. Preferably, the Mn content is 0.10% or more, more preferably 0.15% or more. Further, the Mn content is preferably 0.60% or less, and more preferably 0.30% or less.
Ｐ：０．０４％以下
Ｐは鋼に不可避的に含まれる元素であるが、耐食性および加工性に対して有害な元素であるので可能な限り低減することが好ましい。特に、Ｐ含有量が０．０４％を超えると固溶強化により加工性が顕著に低下する。よって、Ｐ含有量は０．０４％以下とする。好ましくは、Ｐ含有量は０．０３％以下である。 P: 0.04% or less P is an element that is inevitably contained in steel, but it is an element harmful to corrosion resistance and workability, so it is preferable to reduce it as much as possible. In particular, if the P content exceeds 0.04%, solid-solution strengthening significantly reduces the workability. Therefore, the P content is 0.04% or less. Preferably, the P content is 0.03% or less.
Ｐは鋼に不可避的に含まれる元素であるが、耐食性および加工性に対して有害な元素であるので可能な限り低減することが好ましい。特に、Ｐ含有量が０．０４％を超えると固溶強化により加工性が顕著に低下する。よって、Ｐ含有量は０．０４％以下とする。好ましくは、Ｐ含有量は０．０３％以下である。 P: 0.04% or less P is an element that is inevitably contained in steel, but it is an element harmful to corrosion resistance and workability, so it is preferable to reduce it as much as possible. In particular, if the P content exceeds 0.04%, solid-solution strengthening significantly reduces the workability. Therefore, the P content is 0.04% or less. Preferably, the P content is 0.03% or less.
Ｓ：０．０１％以下
ＳもＰと同様に鋼に不可避的に含まれる元素であるが、耐食性および加工性に対して有害な元素であるので可能な限り低減するのが好ましい。特に、Ｓ含有量が０．０１％を超えると耐食性が顕著に低下する。よって、Ｓ含有量は０．０１％以下とする。好ましくは、Ｓ含有量は０．００８％以下である。さらに好ましくは、Ｓ含有量は０．００３％以下である。 S: 0.01% or less S is an element that is inevitably contained in steel similarly to P, but it is an element harmful to corrosion resistance and workability, so it is preferable to reduce it as much as possible. In particular, when the S content exceeds 0.01%, the corrosion resistance is significantly reduced. Therefore, the S content is 0.01% or less. Preferably, the S content is 0.008% or less. More preferably, the S content is 0.003% or less.
ＳもＰと同様に鋼に不可避的に含まれる元素であるが、耐食性および加工性に対して有害な元素であるので可能な限り低減するのが好ましい。特に、Ｓ含有量が０．０１％を超えると耐食性が顕著に低下する。よって、Ｓ含有量は０．０１％以下とする。好ましくは、Ｓ含有量は０．００８％以下である。さらに好ましくは、Ｓ含有量は０．００３％以下である。 S: 0.01% or less S is an element that is inevitably contained in steel similarly to P, but it is an element harmful to corrosion resistance and workability, so it is preferable to reduce it as much as possible. In particular, when the S content exceeds 0.01%, the corrosion resistance is significantly reduced. Therefore, the S content is 0.01% or less. Preferably, the S content is 0.008% or less. More preferably, the S content is 0.003% or less.
Ａｌ：０．０１～０．１０％
Ａｌは有効な脱酸剤である。さらに、Ａｌは窒素との親和力がＣｒよりも強いため、溶接部に窒素が侵入した場合に、窒素をＣｒ窒化物ではなくＡｌ窒化物として析出させて、鋭敏化を抑制する効果がある。これらの効果は、Ａｌを０．０１％以上含有することで得られる。しかし、０．１０％を超えるＡｌを含有すると、溶接時の溶け込み性が低下して溶接作業性が低下するので好ましくない。そのため、Ａｌ含有量は０．０１～０．１０％の範囲とする。好ましくは、Ａｌ含有量は０．０２％以上であり、さらに好ましくは０．０３％以上である。また、好ましくは、Ａｌ含有量は０．０６％以下であり、さらに好ましくは、０．０４％以下である。 Al: 0.01 to 0.10%
Al is an effective deoxidizer. Furthermore, since Al has a stronger affinity for nitrogen than Cr, when nitrogen penetrates into the welded portion, it has the effect of precipitating nitrogen as Al nitride instead of Cr nitride and suppressing sensitization. These effects are obtained by containing Al by 0.01% or more. However, if Al is contained in excess of 0.10%, the meltability during welding is deteriorated and the welding workability is deteriorated, which is not preferable. Therefore, the Al content is set to the range of 0.01 to 0.10%. The Al content is preferably 0.02% or more, more preferably 0.03% or more. Further, the Al content is preferably 0.06% or less, and more preferably 0.04% or less.
Ａｌは有効な脱酸剤である。さらに、Ａｌは窒素との親和力がＣｒよりも強いため、溶接部に窒素が侵入した場合に、窒素をＣｒ窒化物ではなくＡｌ窒化物として析出させて、鋭敏化を抑制する効果がある。これらの効果は、Ａｌを０．０１％以上含有することで得られる。しかし、０．１０％を超えるＡｌを含有すると、溶接時の溶け込み性が低下して溶接作業性が低下するので好ましくない。そのため、Ａｌ含有量は０．０１～０．１０％の範囲とする。好ましくは、Ａｌ含有量は０．０２％以上であり、さらに好ましくは０．０３％以上である。また、好ましくは、Ａｌ含有量は０．０６％以下であり、さらに好ましくは、０．０４％以下である。 Al: 0.01 to 0.10%
Al is an effective deoxidizer. Furthermore, since Al has a stronger affinity for nitrogen than Cr, when nitrogen penetrates into the welded portion, it has the effect of precipitating nitrogen as Al nitride instead of Cr nitride and suppressing sensitization. These effects are obtained by containing Al by 0.01% or more. However, if Al is contained in excess of 0.10%, the meltability during welding is deteriorated and the welding workability is deteriorated, which is not preferable. Therefore, the Al content is set to the range of 0.01 to 0.10%. The Al content is preferably 0.02% or more, more preferably 0.03% or more. Further, the Al content is preferably 0.06% or less, and more preferably 0.04% or less.
Ｃｒ：１０．０～２０．０％
Ｃｒは、ステンレス鋼の耐食性を確保するために最も重要な元素である。その含有量が１０．０％未満では、自動車排気ガス雰囲気において十分な耐食性が得られない。一方、２０．０％を超えてＣｒを含有すると、所定量のＮｉを含有させたとしても、熱間圧延工程におけるオーステナイト相の生成量が不足して、熱間圧延工程における金属組織の微細化効果が不十分となって熱延板焼鈍後の平均結晶粒径が２０μｍを上回り、打ち抜き加工時に所定の寸法精度が得られない。そのため、Ｃｒ含有量は１０．０～２０．０％の範囲とする。好ましくは、Ｃｒ含有量は１０．０～１７．０％の範囲である。より好ましくは、Ｃｒ含有量は１０．５％以上であり、さらに好ましくは１１．２％以上である。また、より好ましくは、Ｃｒ含有量は１２．０％以下であり、さらに好ましくは、１１．７％以下である。 Cr: 10.0-20.0%
Cr is the most important element for ensuring the corrosion resistance of stainless steel. If the content is less than 10.0%, sufficient corrosion resistance cannot be obtained in an automobile exhaust gas atmosphere. On the other hand, if Cr is contained in excess of 20.0%, even if a predetermined amount of Ni is contained, the amount of austenite phase generated in the hot rolling process is insufficient, and the metal structure is refined in the hot rolling process. The effect becomes insufficient, and the average crystal grain size after hot-rolled sheet annealing exceeds 20 μm, and a predetermined dimensional accuracy cannot be obtained during punching. Therefore, the Cr content is set in the range of 10.0 to 20.0%. Preferably, the Cr content is in the range of 10.0 to 17.0%. More preferably, the Cr content is 10.5% or more, and further preferably 11.2% or more. Further, the Cr content is more preferably 12.0% or less, and further preferably 11.7% or less.
Ｃｒは、ステンレス鋼の耐食性を確保するために最も重要な元素である。その含有量が１０．０％未満では、自動車排気ガス雰囲気において十分な耐食性が得られない。一方、２０．０％を超えてＣｒを含有すると、所定量のＮｉを含有させたとしても、熱間圧延工程におけるオーステナイト相の生成量が不足して、熱間圧延工程における金属組織の微細化効果が不十分となって熱延板焼鈍後の平均結晶粒径が２０μｍを上回り、打ち抜き加工時に所定の寸法精度が得られない。そのため、Ｃｒ含有量は１０．０～２０．０％の範囲とする。好ましくは、Ｃｒ含有量は１０．０～１７．０％の範囲である。より好ましくは、Ｃｒ含有量は１０．５％以上であり、さらに好ましくは１１．２％以上である。また、より好ましくは、Ｃｒ含有量は１２．０％以下であり、さらに好ましくは、１１．７％以下である。 Cr: 10.0-20.0%
Cr is the most important element for ensuring the corrosion resistance of stainless steel. If the content is less than 10.0%, sufficient corrosion resistance cannot be obtained in an automobile exhaust gas atmosphere. On the other hand, if Cr is contained in excess of 20.0%, even if a predetermined amount of Ni is contained, the amount of austenite phase generated in the hot rolling process is insufficient, and the metal structure is refined in the hot rolling process. The effect becomes insufficient, and the average crystal grain size after hot-rolled sheet annealing exceeds 20 μm, and a predetermined dimensional accuracy cannot be obtained during punching. Therefore, the Cr content is set in the range of 10.0 to 20.0%. Preferably, the Cr content is in the range of 10.0 to 17.0%. More preferably, the Cr content is 10.5% or more, and further preferably 11.2% or more. Further, the Cr content is more preferably 12.0% or less, and further preferably 11.7% or less.
Ｎｉ：０．５０～２．００％
Ｎｉはオーステナイト生成元素であり、熱間圧延工程における圧延加工前の加熱時に生成するオーステナイト量を増加させる効果がある。本発明においては、ＣｒおよびＮｉの含有量を所定量に制御することによって、熱間圧延工程における加熱時にオーステナイト相を生成させる。このオーステナイト相の生成によって、鋳造時に形成された粗大な金属組織が微細化するとともに、オーステナイト相には熱間圧延中に動的および／または静的再結晶が生じるために熱間圧延後の金属組織は一層微細化し、結果として熱延板焼鈍後の金属組織の微細化に寄与する。これらの効果は、Ｎｉを０．５０％以上含有することで得られる。一方、Ｎｉ含有量が２．００％を超えると、過剰な固溶Ｎｉによる熱延焼鈍後の鋼板の過度な硬質化に起因した打ち抜き割れが生じやすくなる。そのため、Ｎｉ含有量は０．５０～２．００％とする。好ましくは、Ｎｉ含有量は０．６０％以上であり、さらに好ましくは０．７０％以上である。さらに好ましくは０．７５％以上である。また、より好ましくは、Ｎｉ含有量は１．５０％以下であり、さらに好ましくは、１．００％以下である。 Ni: 0.50-2.00%
Ni is an austenite-forming element and has an effect of increasing the amount of austenite generated during heating before rolling in the hot rolling step. In the present invention, the austenite phase is generated at the time of heating in the hot rolling step by controlling the contents of Cr and Ni to predetermined amounts. Due to the formation of the austenite phase, the coarse metal structure formed during casting is refined, and the austenite phase undergoes dynamic and / or static recrystallization during hot rolling. The structure is further refined, and as a result, it contributes to the refinement of the metal structure after hot-rolled sheet annealing. These effects can be obtained by containing 0.50% or more of Ni. On the other hand, if the Ni content exceeds 2.00%, punching cracks due to excessive hardening of the steel sheet after hot rolling annealing due to excessive solid solution Ni are likely to occur. Therefore, the Ni content is 0.50 to 2.00%. The Ni content is preferably 0.60% or more, more preferably 0.70% or more. More preferably, it is 0.75% or more. Further, the Ni content is more preferably 1.50% or less, and further preferably 1.00% or less.
Ｎｉはオーステナイト生成元素であり、熱間圧延工程における圧延加工前の加熱時に生成するオーステナイト量を増加させる効果がある。本発明においては、ＣｒおよびＮｉの含有量を所定量に制御することによって、熱間圧延工程における加熱時にオーステナイト相を生成させる。このオーステナイト相の生成によって、鋳造時に形成された粗大な金属組織が微細化するとともに、オーステナイト相には熱間圧延中に動的および／または静的再結晶が生じるために熱間圧延後の金属組織は一層微細化し、結果として熱延板焼鈍後の金属組織の微細化に寄与する。これらの効果は、Ｎｉを０．５０％以上含有することで得られる。一方、Ｎｉ含有量が２．００％を超えると、過剰な固溶Ｎｉによる熱延焼鈍後の鋼板の過度な硬質化に起因した打ち抜き割れが生じやすくなる。そのため、Ｎｉ含有量は０．５０～２．００％とする。好ましくは、Ｎｉ含有量は０．６０％以上であり、さらに好ましくは０．７０％以上である。さらに好ましくは０．７５％以上である。また、より好ましくは、Ｎｉ含有量は１．５０％以下であり、さらに好ましくは、１．００％以下である。 Ni: 0.50-2.00%
Ni is an austenite-forming element and has an effect of increasing the amount of austenite generated during heating before rolling in the hot rolling step. In the present invention, the austenite phase is generated at the time of heating in the hot rolling step by controlling the contents of Cr and Ni to predetermined amounts. Due to the formation of the austenite phase, the coarse metal structure formed during casting is refined, and the austenite phase undergoes dynamic and / or static recrystallization during hot rolling. The structure is further refined, and as a result, it contributes to the refinement of the metal structure after hot-rolled sheet annealing. These effects can be obtained by containing 0.50% or more of Ni. On the other hand, if the Ni content exceeds 2.00%, punching cracks due to excessive hardening of the steel sheet after hot rolling annealing due to excessive solid solution Ni are likely to occur. Therefore, the Ni content is 0.50 to 2.00%. The Ni content is preferably 0.60% or more, more preferably 0.70% or more. More preferably, it is 0.75% or more. Further, the Ni content is more preferably 1.50% or less, and further preferably 1.00% or less.
Ｔｉ：０．１０～０．４０％
ＴｉはＣ、Ｎと優先的に結合して、Ｃｒ炭窒化物の析出を抑制し、再結晶温度を低下させるとともに、Ｃｒ炭窒化物の析出による鋭敏化に起因した耐食性の低下を抑制する効果がある。これらの効果を得るためには０．１０％以上のＴｉの含有が必要である。しかし、Ｔｉ含有量が０．４０％を超えると、鋳造工程において粗大なＴｉ炭窒化物が生成して鋼板の靭性が著しく低下することに加え、表面欠陥を引き起こすため製造上好ましくない。そのため、Ｔｉ含有量は０．１０～０．４０％とする。好ましくは、Ｔｉ含有量は０．１５％以上であり、さらに好ましくは０．２０％以上である。また、好ましくは、Ｔｉ含有量は０．３５％以下であり、さらに好ましくは、Ｔｉ含有量は０．３０％以下である。なお、溶接部耐食性の観点では式：Ｔｉ／（Ｃ＋Ｎ）≧８（該式中のＴｉ、ＣおよびＮは各元素の含有量（質量％）である）を満たすＴｉ含有量とすることが好ましい。 Ti: 0.10 to 0.40%
Ti binds preferentially to C and N, suppresses the precipitation of Cr carbonitrides, lowers the recrystallization temperature, and suppresses the deterioration of corrosion resistance due to sensitization due to the precipitation of Cr carbonitrides. There is. To obtain these effects, it is necessary to contain 0.10% or more of Ti. However, if the Ti content exceeds 0.40%, coarse Ti carbonitrides are generated in the casting process, the toughness of the steel sheet is significantly reduced, and surface defects are caused, which is not preferable in manufacturing. Therefore, the Ti content is set to 0.10 to 0.40%. Preferably, the Ti content is 0.15% or more, more preferably 0.20% or more. Further, the Ti content is preferably 0.35% or less, and more preferably the Ti content is 0.30% or less. From the viewpoint of weld corrosion resistance, it is preferable to set the Ti content to satisfy the formula: Ti / (C + N) ≧ 8 (Ti, C and N in the formula are the contents (mass%) of each element). .
ＴｉはＣ、Ｎと優先的に結合して、Ｃｒ炭窒化物の析出を抑制し、再結晶温度を低下させるとともに、Ｃｒ炭窒化物の析出による鋭敏化に起因した耐食性の低下を抑制する効果がある。これらの効果を得るためには０．１０％以上のＴｉの含有が必要である。しかし、Ｔｉ含有量が０．４０％を超えると、鋳造工程において粗大なＴｉ炭窒化物が生成して鋼板の靭性が著しく低下することに加え、表面欠陥を引き起こすため製造上好ましくない。そのため、Ｔｉ含有量は０．１０～０．４０％とする。好ましくは、Ｔｉ含有量は０．１５％以上であり、さらに好ましくは０．２０％以上である。また、好ましくは、Ｔｉ含有量は０．３５％以下であり、さらに好ましくは、Ｔｉ含有量は０．３０％以下である。なお、溶接部耐食性の観点では式：Ｔｉ／（Ｃ＋Ｎ）≧８（該式中のＴｉ、ＣおよびＮは各元素の含有量（質量％）である）を満たすＴｉ含有量とすることが好ましい。 Ti: 0.10 to 0.40%
Ti binds preferentially to C and N, suppresses the precipitation of Cr carbonitrides, lowers the recrystallization temperature, and suppresses the deterioration of corrosion resistance due to sensitization due to the precipitation of Cr carbonitrides. There is. To obtain these effects, it is necessary to contain 0.10% or more of Ti. However, if the Ti content exceeds 0.40%, coarse Ti carbonitrides are generated in the casting process, the toughness of the steel sheet is significantly reduced, and surface defects are caused, which is not preferable in manufacturing. Therefore, the Ti content is set to 0.10 to 0.40%. Preferably, the Ti content is 0.15% or more, more preferably 0.20% or more. Further, the Ti content is preferably 0.35% or less, and more preferably the Ti content is 0.30% or less. From the viewpoint of weld corrosion resistance, it is preferable to set the Ti content to satisfy the formula: Ti / (C + N) ≧ 8 (Ti, C and N in the formula are the contents (mass%) of each element). .
Ｎ：０．００１～０．０２０％
Ｎ含有量が０．０２０％を超えると、加工性の低下および溶接部の耐食性の低下が顕著になる。耐食性の観点からＮ含有量は低いほど好ましいが、Ｎ含有量を０．００１％未満にまで低減するには長時間の精錬が必要となり、製造コストの上昇および生産性の低下を招くため好ましくない。よって、Ｎ含有量は０．００１～０．０２０％の範囲とする。好ましくは、Ｎ含有量は０．００５％以上であり、さらに好ましくは０．００７％以上である。また、好ましくは、Ｎ含有量は０．０１５％以下であり、さらに好ましくは、Ｎ含有量は０．０１２％以下である。 N: 0.001 to 0.020%
When the N content exceeds 0.020%, the workability and the corrosion resistance of the welded part are significantly reduced. From the viewpoint of corrosion resistance, the lower the N content is, the better, but it is not preferable because it requires refining for a long time to reduce the N content to less than 0.001%, which leads to an increase in manufacturing cost and a decrease in productivity. . Therefore, the N content is set in the range of 0.001 to 0.020%. Preferably, the N content is 0.005% or more, more preferably 0.007% or more. In addition, the N content is preferably 0.015% or less, and more preferably the N content is 0.012% or less.
Ｎ含有量が０．０２０％を超えると、加工性の低下および溶接部の耐食性の低下が顕著になる。耐食性の観点からＮ含有量は低いほど好ましいが、Ｎ含有量を０．００１％未満にまで低減するには長時間の精錬が必要となり、製造コストの上昇および生産性の低下を招くため好ましくない。よって、Ｎ含有量は０．００１～０．０２０％の範囲とする。好ましくは、Ｎ含有量は０．００５％以上であり、さらに好ましくは０．００７％以上である。また、好ましくは、Ｎ含有量は０．０１５％以下であり、さらに好ましくは、Ｎ含有量は０．０１２％以下である。 N: 0.001 to 0.020%
When the N content exceeds 0.020%, the workability and the corrosion resistance of the welded part are significantly reduced. From the viewpoint of corrosion resistance, the lower the N content is, the better, but it is not preferable because it requires refining for a long time to reduce the N content to less than 0.001%, which leads to an increase in manufacturing cost and a decrease in productivity. . Therefore, the N content is set in the range of 0.001 to 0.020%. Preferably, the N content is 0.005% or more, more preferably 0.007% or more. In addition, the N content is preferably 0.015% or less, and more preferably the N content is 0.012% or less.
本発明は、上記必須成分を含有し残部がＦｅおよび不可避的不純物からなることを特徴とするフェライト系ステンレス鋼である。さらに、必要に応じて、Ｃｕ、Ｍｏ、ＷおよびＣｏのうちから選ばれる１種または２種以上、あるいは／さらに、Ｖ、Ｎｂ、Ｚｒ、ＲＥＭ、Ｂ、ＭｇおよびＣａのうちから選ばれる１種または２種以上を、下記の範囲で含有することができる。なお、下記の範囲において下限値未満で下記の元素を含有しても本発明の効果は害されないことから、下記の元素を下限値未満で含む場合、その元素は不可避的不純物とする。
The present invention is a ferritic stainless steel containing the above essential components and the balance being Fe and inevitable impurities. Furthermore, if necessary, one or more selected from Cu, Mo, W and Co, or / and further one selected from V, Nb, Zr, REM, B, Mg and Ca. Alternatively, two or more kinds may be contained within the following range. In addition, since the effects of the present invention are not impaired even if the following elements are contained below the lower limit in the range below, the effect of the present invention is not impaired when the following elements are contained below the lower limit.
Ｃｕ：０．０１～１．００％
Ｃｕは、水溶液中や弱酸性の水滴が付着した場合の母材および溶接部の耐食性を向上させるのに特に有効な元素である。この効果は０．０１％以上の含有により得られ、その効果はＣｕ含有量が多いほど高くなる。しかし、１．００％を超えてＣｕを含有すると、熱間加工性が低下して表面欠陥を誘引する場合がある。さらには焼鈍後の脱スケールが困難となる場合もある。そのため、Ｃｕを含有する場合は、Ｃｕ含有量は０．０１～１．００％の範囲とすることが好ましい。より好ましくは、Ｃｕ含有量は０．１０％以上であり、さらに好ましくは０．３０％以上である。また、より好ましくは、Ｃｕ含有量は０．６０％以下であり、さらに好ましくは、０．４５％以下である。 Cu: 0.01-1.00%
Cu is an element that is particularly effective in improving the corrosion resistance of the base material and the welded portion when an aqueous solution or weakly acidic water drops adhere. This effect is obtained when the content is 0.01% or more, and the higher the Cu content, the higher the effect. However, if Cu is contained in excess of 1.00%, the hot workability may be deteriorated and surface defects may be induced. Furthermore, descaling after annealing may be difficult in some cases. Therefore, when Cu is contained, the Cu content is preferably in the range of 0.01 to 1.00%. More preferably, the Cu content is 0.10% or more, and further preferably 0.30% or more. Further, the Cu content is more preferably 0.60% or less, and further preferably 0.45% or less.
Ｃｕは、水溶液中や弱酸性の水滴が付着した場合の母材および溶接部の耐食性を向上させるのに特に有効な元素である。この効果は０．０１％以上の含有により得られ、その効果はＣｕ含有量が多いほど高くなる。しかし、１．００％を超えてＣｕを含有すると、熱間加工性が低下して表面欠陥を誘引する場合がある。さらには焼鈍後の脱スケールが困難となる場合もある。そのため、Ｃｕを含有する場合は、Ｃｕ含有量は０．０１～１．００％の範囲とすることが好ましい。より好ましくは、Ｃｕ含有量は０．１０％以上であり、さらに好ましくは０．３０％以上である。また、より好ましくは、Ｃｕ含有量は０．６０％以下であり、さらに好ましくは、０．４５％以下である。 Cu: 0.01-1.00%
Cu is an element that is particularly effective in improving the corrosion resistance of the base material and the welded portion when an aqueous solution or weakly acidic water drops adhere. This effect is obtained when the content is 0.01% or more, and the higher the Cu content, the higher the effect. However, if Cu is contained in excess of 1.00%, the hot workability may be deteriorated and surface defects may be induced. Furthermore, descaling after annealing may be difficult in some cases. Therefore, when Cu is contained, the Cu content is preferably in the range of 0.01 to 1.00%. More preferably, the Cu content is 0.10% or more, and further preferably 0.30% or more. Further, the Cu content is more preferably 0.60% or less, and further preferably 0.45% or less.
Ｍｏ：０．０１～２．００％
Ｍｏは、ステンレス鋼の耐食性を顕著に向上させる元素である。この効果は０．０１％以上の含有によって得られ、その効果は含有量が多いほど向上する。しかし、Ｍｏ含有量が２．００％を超えると、熱間圧延時の圧延負荷が大きくなり製造性が低下したり、鋼板強度の過度な上昇が生じたりする場合がある。また、Ｍｏは高価な元素であることから、多量の含有は製造コストを増大させる。そのため、Ｍｏを含有する場合は、Ｍｏ含有量は０．０１～２．００％とすることが好ましい。より好ましくは、Ｍｏ含有量は０．１０％以上であり、さらに好ましくは０．３０％以上である。また、より好ましくは、Ｍｏ含有量は１．４０％以下であり、さらに好ましくは、０．９０％以下である。 Mo: 0.01-2.00%
Mo is an element that significantly improves the corrosion resistance of stainless steel. This effect is obtained when the content is 0.01% or more, and the effect is improved as the content is increased. However, if the Mo content exceeds 2.00%, the rolling load at the time of hot rolling increases, the productivity may decrease, and the steel sheet strength may excessively increase. Moreover, since Mo is an expensive element, the inclusion of a large amount increases the manufacturing cost. Therefore, when Mo is contained, the Mo content is preferably 0.01 to 2.00%. More preferably, the Mo content is 0.10% or more, and further preferably 0.30% or more. Further, the Mo content is more preferably 1.40% or less, and further preferably 0.90% or less.
Ｍｏは、ステンレス鋼の耐食性を顕著に向上させる元素である。この効果は０．０１％以上の含有によって得られ、その効果は含有量が多いほど向上する。しかし、Ｍｏ含有量が２．００％を超えると、熱間圧延時の圧延負荷が大きくなり製造性が低下したり、鋼板強度の過度な上昇が生じたりする場合がある。また、Ｍｏは高価な元素であることから、多量の含有は製造コストを増大させる。そのため、Ｍｏを含有する場合は、Ｍｏ含有量は０．０１～２．００％とすることが好ましい。より好ましくは、Ｍｏ含有量は０．１０％以上であり、さらに好ましくは０．３０％以上である。また、より好ましくは、Ｍｏ含有量は１．４０％以下であり、さらに好ましくは、０．９０％以下である。 Mo: 0.01-2.00%
Mo is an element that significantly improves the corrosion resistance of stainless steel. This effect is obtained when the content is 0.01% or more, and the effect is improved as the content is increased. However, if the Mo content exceeds 2.00%, the rolling load at the time of hot rolling increases, the productivity may decrease, and the steel sheet strength may excessively increase. Moreover, since Mo is an expensive element, the inclusion of a large amount increases the manufacturing cost. Therefore, when Mo is contained, the Mo content is preferably 0.01 to 2.00%. More preferably, the Mo content is 0.10% or more, and further preferably 0.30% or more. Further, the Mo content is more preferably 1.40% or less, and further preferably 0.90% or less.
Ｗ：０．０１～０．２０％
Ｗは、Ｍｏと同様に耐食性を向上させる効果がある。この効果は０．０１％以上のＷの含有により得られる。しかし、０．２０％を超えてＷを含有すると強度が上昇し、圧延荷重の増大等による製造性の低下を招く場合がある。そのため、Ｗを含有する場合は、Ｗ含有量は０．０１～０．２０％の範囲とすることが好ましい。さらに好ましくは、Ｗ含有量は０．０５％以上である。また、さらに好ましくは、Ｗ含有量は０．１５％以下である。 W: 0.01 to 0.20%
W has an effect of improving the corrosion resistance similarly to Mo. This effect is obtained by containing 0.01% or more of W. However, if W is contained in excess of 0.20%, the strength is increased and the productivity may be decreased due to an increase in rolling load. Therefore, when W is contained, the W content is preferably in the range of 0.01 to 0.20%. More preferably, the W content is 0.05% or more. Further, more preferably, the W content is 0.15% or less.
Ｗは、Ｍｏと同様に耐食性を向上させる効果がある。この効果は０．０１％以上のＷの含有により得られる。しかし、０．２０％を超えてＷを含有すると強度が上昇し、圧延荷重の増大等による製造性の低下を招く場合がある。そのため、Ｗを含有する場合は、Ｗ含有量は０．０１～０．２０％の範囲とすることが好ましい。さらに好ましくは、Ｗ含有量は０．０５％以上である。また、さらに好ましくは、Ｗ含有量は０．１５％以下である。 W: 0.01 to 0.20%
W has an effect of improving the corrosion resistance similarly to Mo. This effect is obtained by containing 0.01% or more of W. However, if W is contained in excess of 0.20%, the strength is increased and the productivity may be decreased due to an increase in rolling load. Therefore, when W is contained, the W content is preferably in the range of 0.01 to 0.20%. More preferably, the W content is 0.05% or more. Further, more preferably, the W content is 0.15% or less.
Ｃｏ：０．０１～０．２０％
Ｃｏは、靭性を向上させる元素である。この効果は０．０１％以上のＣｏの含有によって得られる。一方、Ｃｏ含有量が０．２０％を超えると加工性が低下する場合がある。そのため、Ｃｏを含有する場合は、Ｃｏ含有量は０．０１～０．２０％の範囲とすることが好ましい。 Co: 0.01 to 0.20%
Co is an element that improves toughness. This effect is obtained by containing 0.01% or more of Co. On the other hand, if the Co content exceeds 0.20%, the workability may decrease. Therefore, when Co is contained, the Co content is preferably in the range of 0.01 to 0.20%.
Ｃｏは、靭性を向上させる元素である。この効果は０．０１％以上のＣｏの含有によって得られる。一方、Ｃｏ含有量が０．２０％を超えると加工性が低下する場合がある。そのため、Ｃｏを含有する場合は、Ｃｏ含有量は０．０１～０．２０％の範囲とすることが好ましい。 Co: 0.01 to 0.20%
Co is an element that improves toughness. This effect is obtained by containing 0.01% or more of Co. On the other hand, if the Co content exceeds 0.20%, the workability may decrease. Therefore, when Co is contained, the Co content is preferably in the range of 0.01 to 0.20%.
Ｖ：０．０１～０．２０％
Ｖは、Ｃ、Ｎと炭窒化物を形成し、溶接時の鋭敏化を抑制して溶接部の耐食性を向上させる。この効果はＶ含有量が０．０１％以上で得られる。一方、Ｖ含有量が０．２０％を超えると加工性および靭性が顕著に低下する場合がある。そのため、Ｖ含有量は０．０１～０．２０％とすることが好ましい。さらに好ましくは、Ｖ含有量は０．０２％以上である。また、さらに好ましくは、Ｖ含有量は０．０５０％以下である。 V: 0.01 to 0.20%
V forms carbonitrides with C and N, suppresses sensitization during welding, and improves the corrosion resistance of the welded portion. This effect is obtained when the V content is 0.01% or more. On the other hand, if the V content exceeds 0.20%, the workability and toughness may be significantly reduced. Therefore, the V content is preferably 0.01 to 0.20%. More preferably, the V content is 0.02% or more. Further, more preferably, the V content is 0.050% or less.
Ｖは、Ｃ、Ｎと炭窒化物を形成し、溶接時の鋭敏化を抑制して溶接部の耐食性を向上させる。この効果はＶ含有量が０．０１％以上で得られる。一方、Ｖ含有量が０．２０％を超えると加工性および靭性が顕著に低下する場合がある。そのため、Ｖ含有量は０．０１～０．２０％とすることが好ましい。さらに好ましくは、Ｖ含有量は０．０２％以上である。また、さらに好ましくは、Ｖ含有量は０．０５０％以下である。 V: 0.01 to 0.20%
V forms carbonitrides with C and N, suppresses sensitization during welding, and improves the corrosion resistance of the welded portion. This effect is obtained when the V content is 0.01% or more. On the other hand, if the V content exceeds 0.20%, the workability and toughness may be significantly reduced. Therefore, the V content is preferably 0.01 to 0.20%. More preferably, the V content is 0.02% or more. Further, more preferably, the V content is 0.050% or less.
Ｎｂ：０．０１～０．１０％
Ｎｂは、結晶粒を微細化させるとともに、微細な炭窒化物として析出することで０．２％耐力を上昇させる効果がある。これらの効果は０．０１％以上のＮｂの含有で得られる。一方、Ｎｂは再結晶温度を上昇させる効果もあり、Ｎｂ含有量が０．１０％を超えると熱延板焼鈍にて十分な再結晶を生じさせるために必要な焼鈍温度が過度に高温となるため、熱延板焼鈍後に本発明が必要とする平均結晶粒径が５～２０μｍであるフェライト単相組織が得られなくなる場合がある。そのため、Ｎｂを含有させる場合には、Ｎｂ含有量は０．０１～０．１０％の範囲とすることが好ましい。さらに好ましくは、Ｎｂ含有量は０．０１～０．０５％である。 Nb: 0.01 to 0.10%
Nb has the effect of increasing the 0.2% proof stress by refining the crystal grains and precipitating as fine carbonitrides. These effects are obtained when the Nb content is 0.01% or more. On the other hand, Nb also has the effect of raising the recrystallization temperature, and if the Nb content exceeds 0.10%, the annealing temperature necessary for causing sufficient recrystallization in hot-rolled sheet annealing becomes excessively high. Therefore, it may not be possible to obtain a ferrite single-phase structure having an average crystal grain size of 5 to 20 μm, which is required by the present invention, after annealing a hot rolled sheet. Therefore, when Nb is contained, the Nb content is preferably in the range of 0.01 to 0.10%. More preferably, the Nb content is 0.01 to 0.05%.
Ｎｂは、結晶粒を微細化させるとともに、微細な炭窒化物として析出することで０．２％耐力を上昇させる効果がある。これらの効果は０．０１％以上のＮｂの含有で得られる。一方、Ｎｂは再結晶温度を上昇させる効果もあり、Ｎｂ含有量が０．１０％を超えると熱延板焼鈍にて十分な再結晶を生じさせるために必要な焼鈍温度が過度に高温となるため、熱延板焼鈍後に本発明が必要とする平均結晶粒径が５～２０μｍであるフェライト単相組織が得られなくなる場合がある。そのため、Ｎｂを含有させる場合には、Ｎｂ含有量は０．０１～０．１０％の範囲とすることが好ましい。さらに好ましくは、Ｎｂ含有量は０．０１～０．０５％である。 Nb: 0.01 to 0.10%
Nb has the effect of increasing the 0.2% proof stress by refining the crystal grains and precipitating as fine carbonitrides. These effects are obtained when the Nb content is 0.01% or more. On the other hand, Nb also has the effect of raising the recrystallization temperature, and if the Nb content exceeds 0.10%, the annealing temperature necessary for causing sufficient recrystallization in hot-rolled sheet annealing becomes excessively high. Therefore, it may not be possible to obtain a ferrite single-phase structure having an average crystal grain size of 5 to 20 μm, which is required by the present invention, after annealing a hot rolled sheet. Therefore, when Nb is contained, the Nb content is preferably in the range of 0.01 to 0.10%. More preferably, the Nb content is 0.01 to 0.05%.
Ｚｒ：０．０１～０．２０％
Ｚｒは、Ｃ、Ｎと結合して鋭敏化を抑制する効果がある。この効果は０．０１％以上のＺｒの含有により得られる。一方、０．２０％を超えてＺｒを含有すると加工性が顕著に低下する場合がある。そのため、Ｚｒを含有する場合、Ｚｒ含有量は０．０１～０．２０％の範囲とすることが好ましい。さらに好ましくは、Ｚｒ含有量は０．０１～０．１０％の範囲とする。 Zr: 0.01 to 0.20%
Zr has the effect of binding to C and N to suppress sensitization. This effect is obtained by containing 0.01% or more of Zr. On the other hand, if Zr is contained in excess of 0.20%, workability may be significantly reduced. Therefore, when Zr is contained, the Zr content is preferably in the range of 0.01 to 0.20%. More preferably, the Zr content is in the range of 0.01 to 0.10%.
Ｚｒは、Ｃ、Ｎと結合して鋭敏化を抑制する効果がある。この効果は０．０１％以上のＺｒの含有により得られる。一方、０．２０％を超えてＺｒを含有すると加工性が顕著に低下する場合がある。そのため、Ｚｒを含有する場合、Ｚｒ含有量は０．０１～０．２０％の範囲とすることが好ましい。さらに好ましくは、Ｚｒ含有量は０．０１～０．１０％の範囲とする。 Zr: 0.01 to 0.20%
Zr has the effect of binding to C and N to suppress sensitization. This effect is obtained by containing 0.01% or more of Zr. On the other hand, if Zr is contained in excess of 0.20%, workability may be significantly reduced. Therefore, when Zr is contained, the Zr content is preferably in the range of 0.01 to 0.20%. More preferably, the Zr content is in the range of 0.01 to 0.10%.
ＲＥＭ：０．００１～０．１００％
ＲＥＭ（Ｒａｒｅ Ｅａｒｔｈ Ｍｅｔａｌｓ：希土類金属）は、耐酸化性を向上させる効果があり、溶接部の酸化皮膜（溶接テンパーカラー）形成を抑制して酸化皮膜直下におけるＣｒ欠乏領域の形成を抑制する。この効果は、ＲＥＭを０．００１％以上含有することで得られる。一方、０．１００％を超えてＲＥＭを含有すると熱間加工性を低下させる場合がある。そのため、ＲＥＭを含有する場合、ＲＥＭ含有量は０．００１～０．１００％の範囲とすることが好ましい。より好ましくは、ＲＥＭ含有量は０．００１～０．０５０％の範囲である。 REM: 0.001 to 0.100%
REM (Rare Earth Metals) has the effect of improving the oxidation resistance, and suppresses the formation of an oxide film (welding temper color) at the welded part to suppress the formation of a Cr-deficient region immediately below the oxide film. This effect is obtained by containing REM in an amount of 0.001% or more. On the other hand, if REM is contained in excess of 0.100%, the hot workability may be deteriorated. Therefore, when REM is contained, the REM content is preferably in the range of 0.001 to 0.100%. More preferably, the REM content is in the range of 0.001 to 0.050%.
ＲＥＭ（Ｒａｒｅ Ｅａｒｔｈ Ｍｅｔａｌｓ：希土類金属）は、耐酸化性を向上させる効果があり、溶接部の酸化皮膜（溶接テンパーカラー）形成を抑制して酸化皮膜直下におけるＣｒ欠乏領域の形成を抑制する。この効果は、ＲＥＭを０．００１％以上含有することで得られる。一方、０．１００％を超えてＲＥＭを含有すると熱間加工性を低下させる場合がある。そのため、ＲＥＭを含有する場合、ＲＥＭ含有量は０．００１～０．１００％の範囲とすることが好ましい。より好ましくは、ＲＥＭ含有量は０．００１～０．０５０％の範囲である。 REM: 0.001 to 0.100%
REM (Rare Earth Metals) has the effect of improving the oxidation resistance, and suppresses the formation of an oxide film (welding temper color) at the welded part to suppress the formation of a Cr-deficient region immediately below the oxide film. This effect is obtained by containing REM in an amount of 0.001% or more. On the other hand, if REM is contained in excess of 0.100%, the hot workability may be deteriorated. Therefore, when REM is contained, the REM content is preferably in the range of 0.001 to 0.100%. More preferably, the REM content is in the range of 0.001 to 0.050%.
Ｂ：０．０００２～０．００２５％
Ｂは、深絞り成形後の耐二次加工脆性を改善するために有効な元素である。この効果はＢの含有量を０．０００２％以上にすることで得られる。一方、０．００２５％を超えてＢを含有すると加工性と靭性が低下する場合がある。そのため、Ｂを含有する場合、Ｂ含有量は０．０００２～０．００２５％の範囲とすることが好ましい。さらに好ましくは、Ｂ含有量は０．０００３％以上である。また、さらに好ましくは、Ｂ含有量は０．０００６％以下である。 B: 0.0002 to 0.0025%
B is an element effective for improving the secondary working brittleness resistance after deep drawing. This effect is obtained when the B content is 0.0002% or more. On the other hand, if B is contained in excess of 0.0025%, the workability and toughness may decrease. Therefore, when B is contained, the B content is preferably in the range of 0.0002 to 0.0025%. More preferably, the B content is 0.0003% or more. Further, more preferably, the B content is 0.0006% or less.
Ｂは、深絞り成形後の耐二次加工脆性を改善するために有効な元素である。この効果はＢの含有量を０．０００２％以上にすることで得られる。一方、０．００２５％を超えてＢを含有すると加工性と靭性が低下する場合がある。そのため、Ｂを含有する場合、Ｂ含有量は０．０００２～０．００２５％の範囲とすることが好ましい。さらに好ましくは、Ｂ含有量は０．０００３％以上である。また、さらに好ましくは、Ｂ含有量は０．０００６％以下である。 B: 0.0002 to 0.0025%
B is an element effective for improving the secondary working brittleness resistance after deep drawing. This effect is obtained when the B content is 0.0002% or more. On the other hand, if B is contained in excess of 0.0025%, the workability and toughness may decrease. Therefore, when B is contained, the B content is preferably in the range of 0.0002 to 0.0025%. More preferably, the B content is 0.0003% or more. Further, more preferably, the B content is 0.0006% or less.
Ｍｇ：０．０００５～０．００３０％
Ｍｇは、スラブの等軸晶率を向上させ、加工性や靭性の向上に有効な元素である。さらに、本発明のようにＴｉを含有する鋼においては、Ｔｉ炭窒化物が粗大化すると靭性が低下するが、ＭｇはＴｉ炭窒化物の粗大化を抑制する効果も有する。これらの効果は、０．０００５％以上のＭｇを含有することで得られる。一方で、Ｍｇ含有量が０．００３０％を超えると、鋼の表面性状を悪化させてしまう場合がある。したがって、Ｍｇを含有する場合、Ｍｇ含有量は０．０００５～０．００３０％の範囲とすることが好ましい。さらに好ましくは、Ｍｇ含有量は０．００１０％以上である。また、さらに好ましくは、Ｍｇ含有量は０．００２０％以下である。 Mg: 0.0005 to 0.0030%
Mg is an element effective for improving the equiaxed crystal ratio of the slab and improving the workability and toughness. Further, in the steel containing Ti as in the present invention, when the Ti carbonitride coarsens, the toughness decreases, but Mg also has the effect of suppressing the coarsening of the Ti carbonitride. These effects are obtained by containing 0.0005% or more of Mg. On the other hand, if the Mg content exceeds 0.0030%, the surface properties of steel may be deteriorated. Therefore, when Mg is contained, the Mg content is preferably in the range of 0.0005 to 0.0030%. More preferably, the Mg content is 0.0010% or more. Further, more preferably, the Mg content is 0.0020% or less.
Ｍｇは、スラブの等軸晶率を向上させ、加工性や靭性の向上に有効な元素である。さらに、本発明のようにＴｉを含有する鋼においては、Ｔｉ炭窒化物が粗大化すると靭性が低下するが、ＭｇはＴｉ炭窒化物の粗大化を抑制する効果も有する。これらの効果は、０．０００５％以上のＭｇを含有することで得られる。一方で、Ｍｇ含有量が０．００３０％を超えると、鋼の表面性状を悪化させてしまう場合がある。したがって、Ｍｇを含有する場合、Ｍｇ含有量は０．０００５～０．００３０％の範囲とすることが好ましい。さらに好ましくは、Ｍｇ含有量は０．００１０％以上である。また、さらに好ましくは、Ｍｇ含有量は０．００２０％以下である。 Mg: 0.0005 to 0.0030%
Mg is an element effective for improving the equiaxed crystal ratio of the slab and improving the workability and toughness. Further, in the steel containing Ti as in the present invention, when the Ti carbonitride coarsens, the toughness decreases, but Mg also has the effect of suppressing the coarsening of the Ti carbonitride. These effects are obtained by containing 0.0005% or more of Mg. On the other hand, if the Mg content exceeds 0.0030%, the surface properties of steel may be deteriorated. Therefore, when Mg is contained, the Mg content is preferably in the range of 0.0005 to 0.0030%. More preferably, the Mg content is 0.0010% or more. Further, more preferably, the Mg content is 0.0020% or less.
Ｃａ：０．０００３～０．００３０％
Ｃａは、連続鋳造の際に発生しやすいＴｉ系介在物の晶出によるノズルの閉塞を防止するのに有効な成分である。その効果は０．０００３％以上のＣａを含有することで得られる。しかし、０．００３０％を超えてＣａを含有すると、ＣａＳの生成により耐食性が低下する場合がある。従って、Ｃａを含有する場合、Ｃａ含有量は０．０００３～０．００３０％の範囲とすることが好ましい。より好ましくは、Ｃａ含有量は０．０００５％以上である。また、より好ましくは、Ｃａ含有量は０．００１５％以下であり、さらに好ましくは、０．００１０％以下である。 Ca: 0.0003 to 0.0030%
Ca is an effective component for preventing clogging of the nozzle due to crystallization of Ti-based inclusions that are likely to occur during continuous casting. The effect is obtained by containing 0.0003% or more of Ca. However, if Ca is contained in excess of 0.0030%, the corrosion resistance may decrease due to the formation of CaS. Therefore, when Ca is contained, the Ca content is preferably in the range of 0.0003 to 0.0030%. More preferably, the Ca content is 0.0005% or more. Further, the Ca content is more preferably 0.0015% or less, and further preferably 0.0010% or less.
Ｃａは、連続鋳造の際に発生しやすいＴｉ系介在物の晶出によるノズルの閉塞を防止するのに有効な成分である。その効果は０．０００３％以上のＣａを含有することで得られる。しかし、０．００３０％を超えてＣａを含有すると、ＣａＳの生成により耐食性が低下する場合がある。従って、Ｃａを含有する場合、Ｃａ含有量は０．０００３～０．００３０％の範囲とすることが好ましい。より好ましくは、Ｃａ含有量は０．０００５％以上である。また、より好ましくは、Ｃａ含有量は０．００１５％以下であり、さらに好ましくは、０．００１０％以下である。 Ca: 0.0003 to 0.0030%
Ca is an effective component for preventing clogging of the nozzle due to crystallization of Ti-based inclusions that are likely to occur during continuous casting. The effect is obtained by containing 0.0003% or more of Ca. However, if Ca is contained in excess of 0.0030%, the corrosion resistance may decrease due to the formation of CaS. Therefore, when Ca is contained, the Ca content is preferably in the range of 0.0003 to 0.0030%. More preferably, the Ca content is 0.0005% or more. Further, the Ca content is more preferably 0.0015% or less, and further preferably 0.0010% or less.
次に、本発明のフェライト系ステンレス熱延焼鈍鋼板の製造方法について説明する。
Next, a method for manufacturing the ferritic stainless steel hot rolled annealed steel sheet of the present invention will be described.
本発明のフェライト系ステンレス熱延焼鈍鋼板は、上記成分組成を有する鋼スラブを用い、常法の熱間圧延により熱延鋼板を得て、該熱延鋼板に対してさらに６００℃以上７５０℃未満で１分～２４時間保持する熱延板焼鈍を行うことによって得られる。
The ferritic stainless steel hot-rolled annealed steel sheet of the present invention uses a steel slab having the above-mentioned composition, and obtains a hot-rolled steel sheet by an ordinary hot rolling, and further 600 ° C or more and less than 750 ° C to the hot-rolled steel sheet. It is obtained by performing hot-rolled sheet annealing for 1 minute to 24 hours.
まずは、上記した成分組成からなる溶鋼を、転炉、電気炉、真空溶解炉等の公知の方法で溶製し、連続鋳造法あるいは造塊－分塊法により鋼素材（スラブ）とする。
First, molten steel composed of the above-mentioned composition is melted by a known method such as a converter, an electric furnace, a vacuum melting furnace, etc., and made into a steel material (slab) by the continuous casting method or the ingot-casting method.
このスラブを、１０５０～１２５０℃で１～２４時間加熱するか、あるいは鋳造後のスラブが上記温度範囲を下回る前に鋳造まま直接、熱間圧延に供する。本発明では熱間圧延の手法ならびに条件について特に限定すべき点はないが、巻取処理を過度に低温で行った場合、熱間圧延後の鋼板が著しく硬質化して次工程の操業が困難となる場合があるため、巻取処理は５５０℃以上で行うことが好ましい。
-This slab is heated at 1050 to 1250 ° C for 1 to 24 hours, or directly subjected to hot rolling as cast before the slab after casting falls below the above temperature range. There is no particular limitation on the method and conditions of hot rolling in the present invention, but when the winding treatment is performed at an excessively low temperature, the steel sheet after hot rolling is significantly hardened and the operation of the next step is difficult. Therefore, the winding treatment is preferably performed at 550 ° C. or higher.
熱延板焼鈍：６００℃以上７５０℃未満で１分～２４時間保持
本発明では上記熱間圧延工程終了後に熱延板焼鈍を行う。熱延板焼鈍において、金属組織を過度に粗大化させることなく、熱間圧延工程で形成させた圧延加工組織を再結晶させるとともに、熱間圧延工程で生成したマルテンサイト相をフェライト相へと変態させる。この効果を得るためには熱延板焼鈍を６００℃以上７５０℃未満で行う必要がある。焼鈍温度が６００℃未満では再結晶が不十分となり、熱延加工組織が微細な回復粒となって金属組織が過度に微細化し、打ち抜き加工時に所定の寸法精度が得られない。また、熱延板焼鈍後の金属組織中に、加工組織やマルテンサイト相が残存して、平均結晶粒径が所定の範囲内であっても、鋼板の過度な硬質化に起因した打ち抜き割れが生じる場合がある。一方、焼鈍温度が７５０℃以上の場合、結晶粒が過度に粗大化して平均結晶粒径２０μｍを上回り、打ち抜き加工時に所定の寸法精度が得られない。保持時間を１分未満とした場合、熱延板焼鈍後の金属組織中に、加工組織やマルテンサイト相が残存して、平均結晶粒径が所定の範囲内であっても、鋼板の過度な硬質化に起因した打ち抜き割れが生じやすくなる。保持時間が２４時間を超えると、結晶粒が過度に粗大化して平均結晶粒径が２０μｍを上回り、打ち抜き加工時に所定の寸法精度が得られない。そのため、熱延板焼鈍は６００℃以上７５０℃未満の温度範囲で１分～２４時間保持することにより行う。好ましくは、熱延板焼鈍温度は６００℃以上であり、さらに好ましくは６４０℃以上である。また、好ましくは、熱延板焼鈍温度は７００℃以下である。好ましい保持時間は１時間以上であり、さらに好ましくは６時間以上である。また、好ましい保持時間は２０時間以下であり、さらに好ましくは、１２時間以下である。なお、熱延板焼鈍の手法に特に限定はなく、箱焼鈍（バッチ焼鈍）、連続焼鈍のいずれで実施してもかまわない。 Hot-rolled sheet annealing: Hold at 600 ° C. or higher and lower than 750 ° C. for 1 minute to 24 hours In the present invention, hot-rolled sheet annealing is performed after the hot rolling process is completed. In hot-rolled sheet annealing, the rolling structure formed in the hot rolling process is recrystallized and the martensite phase generated in the hot rolling process is transformed into a ferrite phase without excessively coarsening the metal structure. Let In order to obtain this effect, it is necessary to perform hot-rolled sheet annealing at 600 ° C. or higher and lower than 750 ° C. If the annealing temperature is less than 600 ° C., recrystallization becomes insufficient, the hot rolled structure becomes fine recovery grains and the metal structure becomes excessively fine, and a predetermined dimensional accuracy cannot be obtained during punching. Further, in the metal structure after hot-rolled sheet annealing, the work structure and martensite phase remain, even if the average crystal grain size is within a predetermined range, punching cracks due to excessive hardening of the steel sheet May occur. On the other hand, when the annealing temperature is 750 ° C. or higher, the crystal grains become excessively coarse and exceed the average crystal grain size of 20 μm, and a predetermined dimensional accuracy cannot be obtained during punching. When the holding time is less than 1 minute, the work structure and the martensite phase remain in the metal structure after hot-rolled sheet annealing, and even if the average crystal grain size is within a predetermined range, the steel plate is excessively excessive. Punching cracks due to hardening tend to occur. If the holding time exceeds 24 hours, the crystal grains become excessively coarse and the average crystal grain size exceeds 20 μm, and a predetermined dimensional accuracy cannot be obtained during punching. Therefore, hot-rolled sheet annealing is performed by holding in the temperature range of 600 ° C or higher and lower than 750 ° C for 1 minute to 24 hours. Preferably, the hot-rolled sheet annealing temperature is 600 ° C or higher, more preferably 640 ° C or higher. Further, preferably, the hot rolled sheet annealing temperature is 700 ° C. or lower. The holding time is preferably 1 hour or longer, more preferably 6 hours or longer. Further, the preferable holding time is 20 hours or less, and more preferably 12 hours or less. The method of hot-rolled sheet annealing is not particularly limited, and may be box annealing (batch annealing) or continuous annealing.
本発明では上記熱間圧延工程終了後に熱延板焼鈍を行う。熱延板焼鈍において、金属組織を過度に粗大化させることなく、熱間圧延工程で形成させた圧延加工組織を再結晶させるとともに、熱間圧延工程で生成したマルテンサイト相をフェライト相へと変態させる。この効果を得るためには熱延板焼鈍を６００℃以上７５０℃未満で行う必要がある。焼鈍温度が６００℃未満では再結晶が不十分となり、熱延加工組織が微細な回復粒となって金属組織が過度に微細化し、打ち抜き加工時に所定の寸法精度が得られない。また、熱延板焼鈍後の金属組織中に、加工組織やマルテンサイト相が残存して、平均結晶粒径が所定の範囲内であっても、鋼板の過度な硬質化に起因した打ち抜き割れが生じる場合がある。一方、焼鈍温度が７５０℃以上の場合、結晶粒が過度に粗大化して平均結晶粒径２０μｍを上回り、打ち抜き加工時に所定の寸法精度が得られない。保持時間を１分未満とした場合、熱延板焼鈍後の金属組織中に、加工組織やマルテンサイト相が残存して、平均結晶粒径が所定の範囲内であっても、鋼板の過度な硬質化に起因した打ち抜き割れが生じやすくなる。保持時間が２４時間を超えると、結晶粒が過度に粗大化して平均結晶粒径が２０μｍを上回り、打ち抜き加工時に所定の寸法精度が得られない。そのため、熱延板焼鈍は６００℃以上７５０℃未満の温度範囲で１分～２４時間保持することにより行う。好ましくは、熱延板焼鈍温度は６００℃以上であり、さらに好ましくは６４０℃以上である。また、好ましくは、熱延板焼鈍温度は７００℃以下である。好ましい保持時間は１時間以上であり、さらに好ましくは６時間以上である。また、好ましい保持時間は２０時間以下であり、さらに好ましくは、１２時間以下である。なお、熱延板焼鈍の手法に特に限定はなく、箱焼鈍（バッチ焼鈍）、連続焼鈍のいずれで実施してもかまわない。 Hot-rolled sheet annealing: Hold at 600 ° C. or higher and lower than 750 ° C. for 1 minute to 24 hours In the present invention, hot-rolled sheet annealing is performed after the hot rolling process is completed. In hot-rolled sheet annealing, the rolling structure formed in the hot rolling process is recrystallized and the martensite phase generated in the hot rolling process is transformed into a ferrite phase without excessively coarsening the metal structure. Let In order to obtain this effect, it is necessary to perform hot-rolled sheet annealing at 600 ° C. or higher and lower than 750 ° C. If the annealing temperature is less than 600 ° C., recrystallization becomes insufficient, the hot rolled structure becomes fine recovery grains and the metal structure becomes excessively fine, and a predetermined dimensional accuracy cannot be obtained during punching. Further, in the metal structure after hot-rolled sheet annealing, the work structure and martensite phase remain, even if the average crystal grain size is within a predetermined range, punching cracks due to excessive hardening of the steel sheet May occur. On the other hand, when the annealing temperature is 750 ° C. or higher, the crystal grains become excessively coarse and exceed the average crystal grain size of 20 μm, and a predetermined dimensional accuracy cannot be obtained during punching. When the holding time is less than 1 minute, the work structure and the martensite phase remain in the metal structure after hot-rolled sheet annealing, and even if the average crystal grain size is within a predetermined range, the steel plate is excessively excessive. Punching cracks due to hardening tend to occur. If the holding time exceeds 24 hours, the crystal grains become excessively coarse and the average crystal grain size exceeds 20 μm, and a predetermined dimensional accuracy cannot be obtained during punching. Therefore, hot-rolled sheet annealing is performed by holding in the temperature range of 600 ° C or higher and lower than 750 ° C for 1 minute to 24 hours. Preferably, the hot-rolled sheet annealing temperature is 600 ° C or higher, more preferably 640 ° C or higher. Further, preferably, the hot rolled sheet annealing temperature is 700 ° C. or lower. The holding time is preferably 1 hour or longer, more preferably 6 hours or longer. Further, the preferable holding time is 20 hours or less, and more preferably 12 hours or less. The method of hot-rolled sheet annealing is not particularly limited, and may be box annealing (batch annealing) or continuous annealing.
得られた熱延焼鈍鋼板には、必要に応じてショットブラストや酸洗による脱スケール処理を行ってもよい。さらに、表面性状を向上させるために、研削や研磨等を施してもよい。また、本発明が提供する熱延焼鈍鋼板はその後、冷間圧延および冷延板焼鈍を行ってもよい。
The obtained hot-rolled annealed steel sheet may be subjected to descaling treatment by shot blasting or pickling if necessary. Furthermore, in order to improve the surface texture, grinding or polishing may be performed. Further, the hot rolled annealed steel sheet provided by the present invention may be subjected to cold rolling and cold rolled sheet annealing thereafter.
以下、本発明を実施例により詳細に説明する。
Hereinafter, the present invention will be described in detail with reference to Examples.
表１に示す化学組成を有するステンレス溶鋼を１００ｋｇ真空溶解炉により溶製した。これらの鋼塊を１１００℃で１時間加熱後、表２に記載の板厚（表２中、熱間圧延終了板厚参照）まで熱間圧延を行った後に６５０℃で１ｈ保持後に炉冷する巻取模擬処理を行って熱延鋼板とした。ついで、表２に記載の温度（表２中、熱延板焼鈍温度参照）で８時間保持後、徐冷する熱延板焼鈍を行い熱延焼鈍鋼板を得た。
なお、得られた各熱延焼鈍鋼板の板厚は、夫々の熱間圧延終了板厚と同じであった。
かくして得られた熱延焼鈍鋼板について、以下の評価を行った。 Molten stainless steel having the chemical composition shown in Table 1 was melted by a 100 kg vacuum melting furnace. These steel ingots are heated at 1100 ° C. for 1 hour, hot-rolled to the plate thickness shown in Table 2 (see the plate thickness after hot rolling in Table 2), and then held at 650 ° C. for 1 h and then cooled in a furnace. A hot-rolled steel sheet was obtained by performing a winding simulation process. Then, after holding for 8 hours at the temperature shown in Table 2 (refer to the hot-rolled sheet annealing temperature in Table 2), the hot-rolled sheet was annealed to obtain a hot-rolled annealed steel sheet.
The plate thickness of each of the obtained hot-rolled annealed steel plates was the same as the hot-rolled finished plate thickness.
The hot rolled annealed steel sheet thus obtained was evaluated as follows.
なお、得られた各熱延焼鈍鋼板の板厚は、夫々の熱間圧延終了板厚と同じであった。
かくして得られた熱延焼鈍鋼板について、以下の評価を行った。 Molten stainless steel having the chemical composition shown in Table 1 was melted by a 100 kg vacuum melting furnace. These steel ingots are heated at 1100 ° C. for 1 hour, hot-rolled to the plate thickness shown in Table 2 (see the plate thickness after hot rolling in Table 2), and then held at 650 ° C. for 1 h and then cooled in a furnace. A hot-rolled steel sheet was obtained by performing a winding simulation process. Then, after holding for 8 hours at the temperature shown in Table 2 (refer to the hot-rolled sheet annealing temperature in Table 2), the hot-rolled sheet was annealed to obtain a hot-rolled annealed steel sheet.
The plate thickness of each of the obtained hot-rolled annealed steel plates was the same as the hot-rolled finished plate thickness.
The hot rolled annealed steel sheet thus obtained was evaluated as follows.
（１）金属組織の評価
板幅中央部から組織観察用試験片を採取し、圧延方向断面を鏡面研磨後、ＳＥＭ／ＥＢＳＤ法を用いて全厚を含む視野で測定および解析を行い、方位差１５°以上の境界を粒界と定義しＡｒｅａ法に基づいて平均結晶粒径を求めた。平均結晶粒径５μｍ以上２０μｍ以下の場合を本発明の範囲内とし、５μｍの未満あるいは２０μｍ超の場合を本発明の範囲外とし、表２中下線を付した。 (1) Evaluation of metal structure A test piece for structure observation was sampled from the center of the plate width, the cross section in the rolling direction was mirror-polished, and then the SEM / EBSD method was used to measure and analyze the field of view including the total thickness to obtain the orientation difference. The boundary of 15 ° or more was defined as a grain boundary, and the average crystal grain size was determined based on the Area method. The case where the average crystal grain size is 5 μm or more and 20 μm or less is within the range of the present invention, and the case where the average grain size is less than 5 μm or over 20 μm is outside the range of the present invention, and underlined in Table 2.
板幅中央部から組織観察用試験片を採取し、圧延方向断面を鏡面研磨後、ＳＥＭ／ＥＢＳＤ法を用いて全厚を含む視野で測定および解析を行い、方位差１５°以上の境界を粒界と定義しＡｒｅａ法に基づいて平均結晶粒径を求めた。平均結晶粒径５μｍ以上２０μｍ以下の場合を本発明の範囲内とし、５μｍの未満あるいは２０μｍ超の場合を本発明の範囲外とし、表２中下線を付した。 (1) Evaluation of metal structure A test piece for structure observation was sampled from the center of the plate width, the cross section in the rolling direction was mirror-polished, and then the SEM / EBSD method was used to measure and analyze the field of view including the total thickness to obtain the orientation difference. The boundary of 15 ° or more was defined as a grain boundary, and the average crystal grain size was determined based on the Area method. The case where the average crystal grain size is 5 μm or more and 20 μm or less is within the range of the present invention, and the case where the average grain size is less than 5 μm or over 20 μm is outside the range of the present invention, and underlined in Table 2.
また、同じく板幅中央部から組織観察用試験片を採取し、圧延方向断面を鏡面研磨後、ピクリン酸－塩酸水溶液により観察用の腐食を行って金属組織を現出させた後、倍率５００倍の光学顕微鏡を用いて観察を行い、金属組織の形態からフェライト相とマルテンサイト相とを区別することにより、各鋼板の金属組織がフェライト単相組織であるか否かを判定した。具体的には、結晶粒内が一様で平坦な形態が観察され、比較的明るいコントラストを呈する領域をフェライト相と判定した。また、結晶粒内に亜粒界やブロック境界等のマルテンサイト相特有の表面形態が観察され、フェライト相に比べて暗いコントラストを呈する領域をマルテンサイト相と判定した。表中、Ｆは金属組織がフェライト単相組織であったことを表している。
Similarly, a test piece for microstructure observation was sampled from the center of the plate width, the cross section in the rolling direction was mirror-polished, and then corroded for observation with an aqueous solution of picric acid-hydrochloric acid to reveal a metal structure, and the magnification was 500 times. It was determined whether the metal structure of each steel sheet was a ferrite single phase structure by distinguishing the ferrite phase and the martensite phase from the morphology of the metal structure by observing with an optical microscope of No. 2. Specifically, a region in which crystal grains are uniform and flat and a relatively bright contrast is exhibited was determined to be a ferrite phase. In addition, the surface morphology peculiar to the martensite phase such as sub-grain boundaries and block boundaries was observed in the crystal grains, and a region exhibiting a darker contrast than the ferrite phase was determined to be the martensite phase. In the table, F represents that the metal structure was a ferrite single phase structure.
（２）耐食性の評価
熱延焼鈍鋼板から、６０×１００ｍｍの試験片を採取し、表面を＃６００エメリーペーパーにより研磨仕上げした後に端面部をシールした試験片を作製し、ＪＩＳ Ｈ ８５０２に規定された塩水噴霧サイクル試験に供した。塩水噴霧サイクル試験は、塩水噴霧（５質量％ＮａＣｌ、３５℃、噴霧２ｈr）→乾燥（６０℃、４ｈr、相対湿度４０％）→湿潤（５０℃、２ｈr、相対湿度≧９５％）を１サイクルとして、５サイクル行った。塩水噴霧サイクル試験を５サイクル実施後の試験片表面を写真撮影し、画像解析により試験片表面の発錆面積を測定し、試験片全面積との比率から発錆面積率（（試験片中の発錆面積／試験片全面積）×１００［％］）を算出した。発錆面積率１０％以下を特に優れた耐食性で合格（◎）、１０％超２５％以下を合格（○）、２５％超を不合格（×）とした。 (2) Evaluation of Corrosion Resistance A test piece of 60 × 100 mm was taken from a hot rolled annealed steel sheet, the surface was polished and finished with # 600 emery paper, and then a test piece whose end face was sealed was prepared and specified in JIS H8502. And subjected to a salt spray cycle test. In the salt spray cycle test, salt spray (5% by mass NaCl, 35 ° C., spray 2 hr) → dry (60 ° C., 4 hr, relative humidity 40%) → wet (50 ° C., 2 hr, relative humidity ≧ 95%) for one cycle As a result, 5 cycles were performed. The surface of the test piece was photographed after 5 cycles of the salt spray cycle test, the rusted area on the surface of the test piece was measured by image analysis, and the rusted area ratio (( Rust area / total area of test piece) × 100 [%]) was calculated. A rusting area ratio of 10% or less was evaluated as excellent corrosion resistance (⊚), a value of more than 10% and 25% or less was evaluated as pass (∘), and a value of more than 25% was evaluated as unacceptable (×).
熱延焼鈍鋼板から、６０×１００ｍｍの試験片を採取し、表面を＃６００エメリーペーパーにより研磨仕上げした後に端面部をシールした試験片を作製し、ＪＩＳ Ｈ ８５０２に規定された塩水噴霧サイクル試験に供した。塩水噴霧サイクル試験は、塩水噴霧（５質量％ＮａＣｌ、３５℃、噴霧２ｈr）→乾燥（６０℃、４ｈr、相対湿度４０％）→湿潤（５０℃、２ｈr、相対湿度≧９５％）を１サイクルとして、５サイクル行った。塩水噴霧サイクル試験を５サイクル実施後の試験片表面を写真撮影し、画像解析により試験片表面の発錆面積を測定し、試験片全面積との比率から発錆面積率（（試験片中の発錆面積／試験片全面積）×１００［％］）を算出した。発錆面積率１０％以下を特に優れた耐食性で合格（◎）、１０％超２５％以下を合格（○）、２５％超を不合格（×）とした。 (2) Evaluation of Corrosion Resistance A test piece of 60 × 100 mm was taken from a hot rolled annealed steel sheet, the surface was polished and finished with # 600 emery paper, and then a test piece whose end face was sealed was prepared and specified in JIS H8502. And subjected to a salt spray cycle test. In the salt spray cycle test, salt spray (5% by mass NaCl, 35 ° C., spray 2 hr) → dry (60 ° C., 4 hr, relative humidity 40%) → wet (50 ° C., 2 hr, relative humidity ≧ 95%) for one cycle As a result, 5 cycles were performed. The surface of the test piece was photographed after 5 cycles of the salt spray cycle test, the rusted area on the surface of the test piece was measured by image analysis, and the rusted area ratio (( Rust area / total area of test piece) × 100 [%]) was calculated. A rusting area ratio of 10% or less was evaluated as excellent corrosion resistance (⊚), a value of more than 10% and 25% or less was evaluated as pass (∘), and a value of more than 25% was evaluated as unacceptable (×).
（３）打ち抜き加工性の評価
熱延焼鈍鋼板から１００ｍｍ×１００ｍｍの試験片を採取した後、該試験片中央部にφ２０ｍｍ（公差±０．１ｍｍ）の孔が形成されるように、直径２０ｍｍの肉抜き用円柱刃を有する上金型（ポンチ）と上金型とのクリアランスが１０％となるように適切に選定された孔を有する下金型（ダイス）を設置したクランクプレス機によって、打ち抜き加工により５枚の試験片を作製した。上記のクリアランス（Ｃ）［％］、ダイスの孔の直径（ダイスの内径）（Ｄｄ）［ｍｍ］及びポンチの直径（Ｄｐ）［ｍｍ］は、板厚（ｔ）［ｍｍ］も含め、以下の式（１）の関係で表される。
Ｃ＝（Ｄｄ－Ｄｐ）÷（２×ｔ）×１００・・・式（１）
このようにして得られた試験片について、試験片外観の目視観察と試験片中央部の孔径をデジタルノギスにより測定した。割れがなく打ち抜き加工後の孔径が５枚の試験片すべてで１９．９～２０．１ｍｍの範囲となっていた場合を合格（○）とした。いずれか１枚でも割れがあるか、孔径が１９．９ｍｍ未満あるいは２０．１ｍｍ超となっていた場合を不合格（×）とした。 (3) Evaluation of punching workability After taking a 100 mm x 100 mm test piece from a hot rolled annealed steel sheet, a diameter of 20 mm is formed so that a hole of φ20 mm (tolerance ± 0.1 mm) is formed in the center of the test piece. Punching with a crank press machine equipped with a lower die (die) having holes appropriately selected so that the clearance between the upper die (punch) having a lightening cylinder blade and the upper die is 10%. Five test pieces were produced by processing. The clearance (C) [%], the diameter of the hole of the die (the inner diameter of the die) (Dd) [mm], and the diameter of the punch (Dp) [mm], including the plate thickness (t) [mm], are as follows. It is expressed by the relationship of the expression (1).
C = (Dd−Dp) ÷ (2 × t) × 100 ... Equation (1)
For the test piece thus obtained, the appearance of the test piece was visually observed and the hole diameter at the center of the test piece was measured with a digital caliper. The case where there was no crack and the hole diameter after punching was within the range of 19.9 to 20.1 mm in all of the five test pieces was regarded as a pass (◯). If any one of them had cracks or the hole diameter was less than 19.9 mm or more than 20.1 mm, it was determined as a failure (x).
熱延焼鈍鋼板から１００ｍｍ×１００ｍｍの試験片を採取した後、該試験片中央部にφ２０ｍｍ（公差±０．１ｍｍ）の孔が形成されるように、直径２０ｍｍの肉抜き用円柱刃を有する上金型（ポンチ）と上金型とのクリアランスが１０％となるように適切に選定された孔を有する下金型（ダイス）を設置したクランクプレス機によって、打ち抜き加工により５枚の試験片を作製した。上記のクリアランス（Ｃ）［％］、ダイスの孔の直径（ダイスの内径）（Ｄｄ）［ｍｍ］及びポンチの直径（Ｄｐ）［ｍｍ］は、板厚（ｔ）［ｍｍ］も含め、以下の式（１）の関係で表される。
Ｃ＝（Ｄｄ－Ｄｐ）÷（２×ｔ）×１００・・・式（１）
このようにして得られた試験片について、試験片外観の目視観察と試験片中央部の孔径をデジタルノギスにより測定した。割れがなく打ち抜き加工後の孔径が５枚の試験片すべてで１９．９～２０．１ｍｍの範囲となっていた場合を合格（○）とした。いずれか１枚でも割れがあるか、孔径が１９．９ｍｍ未満あるいは２０．１ｍｍ超となっていた場合を不合格（×）とした。 (3) Evaluation of punching workability After taking a 100 mm x 100 mm test piece from a hot rolled annealed steel sheet, a diameter of 20 mm is formed so that a hole of φ20 mm (tolerance ± 0.1 mm) is formed in the center of the test piece. Punching with a crank press machine equipped with a lower die (die) having holes appropriately selected so that the clearance between the upper die (punch) having a lightening cylinder blade and the upper die is 10%. Five test pieces were produced by processing. The clearance (C) [%], the diameter of the hole of the die (the inner diameter of the die) (Dd) [mm], and the diameter of the punch (Dp) [mm], including the plate thickness (t) [mm], are as follows. It is expressed by the relationship of the expression (1).
C = (Dd−Dp) ÷ (2 × t) × 100 ... Equation (1)
For the test piece thus obtained, the appearance of the test piece was visually observed and the hole diameter at the center of the test piece was measured with a digital caliper. The case where there was no crack and the hole diameter after punching was within the range of 19.9 to 20.1 mm in all of the five test pieces was regarded as a pass (◯). If any one of them had cracks or the hole diameter was less than 19.9 mm or more than 20.1 mm, it was determined as a failure (x).
試験結果を熱延板焼鈍条件と併せて表２に示す。
Table 2 shows the test results together with the hot rolled sheet annealing conditions.
鋼成分および熱延板焼鈍条件が本発明の範囲を満たすＮｏ．１～３６は、熱間圧延工程における加熱時にオーステナイト相が生成したことに加え、所定の熱延板焼鈍によって結晶粒の過度の粗大化を生じさせることなく再結晶が生じて所定の平均結晶粒径が得られた結果、所定の打ち抜き加工性が得られた。さらに得られた熱延焼鈍板の耐食性を評価した結果、発錆面積率はいずれも２５％以下であり十分な耐食性も有していることが確認された。
No. 1 in which the steel composition and hot-rolled sheet annealing conditions satisfy the scope of the present invention. In Nos. 1 to 36, in addition to the formation of an austenite phase during heating in the hot rolling process, recrystallization occurred without causing excessive coarsening of crystal grains by the predetermined hot-rolled sheet annealing, and a predetermined average crystal grain size was obtained. As a result of obtaining the diameter, a predetermined punching workability was obtained. Further, as a result of evaluating the corrosion resistance of the obtained hot-rolled annealed sheet, it was confirmed that the rusting area ratios were all 25% or less, and that they also had sufficient corrosion resistance.
特に、Ｃｕを含有させた鋼Ａ１９を用いたＮｏ．１９、Ｃｕを含有させた鋼Ａ２１を用いたＮｏ．２１、Ｍｏを含有させた鋼Ａ２０を用いたＮｏ.２０、およびＭｏを含有させた鋼Ａ２２を用いたＮｏ．２２では発錆面積率が１０％以下と一層優れた耐食性が得られた。
In particular, No. 1 using steel A19 containing Cu. No. 19, using steel A21 containing Cu. 21, No. 20 using the steel A20 containing Mo, and No. 21 using the steel A22 containing Mo. In No. 22, more excellent corrosion resistance was obtained with a rusted area ratio of 10% or less.
また、Ｃｒ含有量が１９．７％と高い鋼Ａ３を用いたＮｏ．３およびＣｒ含有量が１９．６％と高い鋼Ａ１８を用いたＮｏ．１８では鋼板表面に形成される不動態皮膜が強固になった結果、発錆面積率が１０％以下と一層優れた耐食性が得られた。
Also, No. 1 using steel A3 with a high Cr content of 19.7%. No. 3 using steel A18 having a high Cr content of 3 and 19.6%. In No. 18, as a result of the passivation film formed on the surface of the steel sheet becoming strong, a more excellent corrosion resistance with a rusting area ratio of 10% or less was obtained.
Ｎｉ含有量が本発明の範囲を下回る鋼Ｂ１を用いたＮｏ．３７では、熱間圧延工程の加熱時にオーステナイト相がほとんど生成しなかった結果、金属組織の微細化効果が得られなかった結果、平均結晶粒径が本発明の範囲を上回り、所定の打ち抜き加工性が得られなかった。
No. using steel B1 whose Ni content is below the range of the present invention. In No. 37, the austenite phase was scarcely generated during heating in the hot rolling process, and the effect of refining the metal structure was not obtained. As a result, the average crystal grain size exceeded the range of the present invention and the predetermined punching workability was obtained. Was not obtained.
Ｎｉ含有量が本発明の範囲を上回る鋼Ｂ２を用いたＮｏ．３８では、所定の平均結晶粒径は得られたものの、固溶Ｎｉ量が過剰であったために鋼板が過度に硬質化した結果、打ち抜き加工時に割れが発生して所定の形状へ加工することができなかった。
No. using steel B2 whose Ni content exceeds the range of the present invention. In No. 38, although a predetermined average crystal grain size was obtained, the steel plate was excessively hardened due to the excessive amount of solid solution Ni, and as a result, cracking occurred during punching, and it was possible to process into a predetermined shape. could not.
Ｃｒ含有量が本発明の範囲を下回る鋼Ｂ３を用いたＮｏ．３９では、Ｃｒ含有量が不足した結果、所定の耐食性が得られなかった。
No. using steel B3 having a Cr content below the range of the present invention. In No. 39, as a result of insufficient Cr content, the predetermined corrosion resistance was not obtained.
Ｃｒ含有量が本発明の範囲を上回る鋼Ｂ４を用いたＮｏ．４０では、所定量のＮｉを含有させたにも関わらず、過剰なＣｒの含有によって熱間圧延工程の加熱時に生成するオーステナイト相が減少した。これにより、熱間圧延工程においてオーステナイト相の生成による微細化効果が十分には得られなかった。その結果、所定の平均結晶粒径が得られず、所定の打ち抜き加工性が得られなかった。
No. using steel B4 having a Cr content exceeding the range of the present invention. In No. 40, the austenite phase generated during heating in the hot rolling step was reduced due to the excessive Cr content, despite the inclusion of a predetermined amount of Ni. As a result, the effect of refining due to the formation of the austenite phase was not sufficiently obtained in the hot rolling process. As a result, a predetermined average crystal grain size was not obtained, and a predetermined punching workability was not obtained.
Ｔｉ含有量が本発明の範囲を下回る鋼Ｂ５を用いたＮｏ．４１では、熱延板焼鈍時にＣｒ炭窒化物が多量に析出したことによる鋭敏化が生じ、所定の耐食性を得ることができなかった。
No. using steel B5 whose Ti content is below the range of the present invention. In No. 41, since a large amount of Cr carbonitride was deposited during annealing of the hot rolled sheet, sensitization occurred, and a predetermined corrosion resistance could not be obtained.
熱延板焼鈍温度が本発明の範囲を上回るＮｏ．４３では、生成した再結晶粒の著しい粗大化が生じた結果、所定の平均結晶粒径が得られず、所定の打ち抜き加工性が得られなかった。
No. whose hot-rolled sheet annealing temperature exceeds the range of the present invention. In No. 43, the recrystallized grains produced were remarkably coarsened, and as a result, a prescribed average crystal grain size could not be obtained and a prescribed punching workability was not obtained.
Ｎｏ．４４は所定の鋼成分を有する鋼Ａ１４を本発明の範囲を上回る８０６℃で焼鈍し、平均結晶粒径を本発明の範囲を上回る３４μｍまで粗大化させた例である。所定の鋼成分を有していたものの、結晶粒が過度に粗大であったために、打ち抜き加工時に著しいダレおよびバリが生じ、所定の打ち抜き加工性が得られなかった。
No. No. 44 is an example in which steel A14 having a predetermined steel composition was annealed at 806 ° C., which exceeds the range of the present invention, and the average grain size was coarsened to 34 μm, which exceeds the range of the present invention. Although it had a predetermined steel composition, the crystal grains were excessively coarse, so that significant sagging and burrs occurred during the punching process, and the predetermined punching workability was not obtained.
本発明で得られるフェライト系ステンレス熱延焼鈍鋼板は、高い加工性と耐食性が要求される用途、例えばバーリング加工部を有するフランジ等への適用に特に好適である。
The ferritic stainless steel hot-rolled and annealed steel sheet obtained in the present invention is particularly suitable for applications requiring high workability and corrosion resistance, for example, flanges having burring portions.
The ferritic stainless steel hot-rolled and annealed steel sheet obtained in the present invention is particularly suitable for applications requiring high workability and corrosion resistance, for example, flanges having burring portions.
Claims (4)
- 質量％で、
Ｃ：０．００１～０．０２０％、
Ｓｉ：０．０５～１．００％、
Ｍｎ：０．０５～１．００％、
Ｐ：０．０４％以下、
Ｓ：０．０１％以下、
Ａｌ：０．０１～０．１０％、
Ｃｒ：１０．０～２０．０％、
Ｎｉ：０．５０～２．００％、
Ｔｉ：０．１０～０．４０％、
Ｎ：０．００１～０．０２０％を含有し、残部がＦｅおよび不可避的不純物からなる成分組成を有し、
金属組織が平均結晶粒径５～２０μｍのフェライト単相組織であるフェライト系ステンレス熱延焼鈍鋼板。 In mass%,
C: 0.001 to 0.020%,
Si: 0.05 to 1.00%,
Mn: 0.05 to 1.00%,
P: 0.04% or less,
S: 0.01% or less,
Al: 0.01 to 0.10%,
Cr: 10.0-20.0%,
Ni: 0.50 to 2.00%,
Ti: 0.10 to 0.40%,
N: 0.001 to 0.020% is contained, with the balance being Fe and inevitable impurities.
A ferritic stainless steel hot-rolled annealed steel sheet whose metal structure is a ferrite single-phase structure having an average crystal grain size of 5 to 20 μm. - 質量％で、さらに、
Ｃｕ：０．０１～１．００％、
Ｍｏ：０．０１～２．００％、
Ｗ：０．０１～０．２０％、
Ｃｏ：０．０１～０．２０％のうちから選ばれる１種または２種以上を含有する請求項１に記載のフェライト系ステンレス熱延焼鈍鋼板。 % By mass,
Cu: 0.01-1.00%,
Mo: 0.01 to 2.00%,
W: 0.01 to 0.20%,
The ferritic stainless steel hot rolled annealed steel sheet according to claim 1, containing one or more selected from the group consisting of Co: 0.01 to 0.20%. - 質量％で、さらに、
Ｖ：０．０１～０．２０％、
Ｎｂ：０．０１～０．１０％、
Ｚｒ：０．０１～０．２０％、
ＲＥＭ：０．００１～０．１００％、
Ｂ：０．０００２～０．００２５％、
Ｍｇ：０．０００５～０．００３０％、
Ｃａ：０．０００３～０．００３０％のうちから選ばれる１種または２種以上を含有する請求項１または２に記載のフェライト系ステンレス熱延焼鈍鋼板。 % By mass,
V: 0.01 to 0.20%,
Nb: 0.01 to 0.10%,
Zr: 0.01 to 0.20%,
REM: 0.001 to 0.100%,
B: 0.0002 to 0.0025%,
Mg: 0.0005 to 0.0030%,
The ferritic stainless steel hot rolled annealed steel sheet according to claim 1 or 2, which contains one or more selected from the group consisting of Ca: 0.0003 to 0.0030%. - 請求項１～３のいずれかに記載のフェライト系ステンレス熱延焼鈍鋼板の製造方法であって、
熱間圧延工程で得られた熱延鋼板について６００℃以上７５０℃未満で１分～２４時間保持する熱延板焼鈍を行うフェライト系ステンレス熱延焼鈍鋼板の製造方法。 A method for manufacturing a hot rolled annealed ferritic stainless steel sheet according to any one of claims 1 to 3,
A method for producing a ferritic stainless hot-rolled annealed steel sheet, which comprises annealing the hot-rolled steel sheet obtained in the hot rolling step at 600 ° C or higher and lower than 750 ° C for 1 minute to 24 hours.
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| CN201980069792.9A CN112888802A (en) | 2018-10-25 | 2019-09-25 | Ferritic stainless steel hot-rolled annealed steel sheet and method for producing same |
| US17/286,657 US20210363604A1 (en) | 2018-10-25 | 2019-09-25 | Hot-rolled and annealed ferritic stainless steel sheet and method for producing the same |
| CA3114743A CA3114743C (en) | 2018-10-25 | 2019-09-25 | Hot-rolled and annealed ferritic stainless steel sheet and method for producing the same |
| JP2020506852A JP7038799B2 (en) | 2018-10-25 | 2019-09-25 | Ferritic stainless hot-rolled annealed steel sheet and its manufacturing method |
| KR1020217011576A KR20210064281A (en) | 2018-10-25 | 2019-09-25 | Ferritic stainless steel hot-rolled annealing steel sheet and manufacturing method thereof |
| MX2021004713A MX2021004713A (en) | 2018-10-25 | 2019-09-25 | Ferrite stainless hot-rolled-and-annealed steel sheet and production method for same. |
| KR1020237031897A KR20230142630A (en) | 2018-10-25 | 2019-09-25 | Ferrite stainless hot-rolled-and-annealed steel sheet and production method for same |
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| JP2018200479 | 2018-10-25 | ||
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| PCT/JP2019/037430 WO2020084987A1 (en) | 2018-10-25 | 2019-09-25 | Ferrite stainless hot-rolled-and-annealed steel sheet and production method for same |
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| US (1) | US20210363604A1 (en) |
| JP (1) | JP7038799B2 (en) |
| KR (2) | KR20230142630A (en) |
| CN (1) | CN112888802A (en) |
| CA (1) | CA3114743C (en) |
| MX (1) | MX2021004713A (en) |
| TW (1) | TWI718712B (en) |
| WO (1) | WO2020084987A1 (en) |
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| WO2014157576A1 (en) * | 2013-03-27 | 2014-10-02 | 新日鐵住金ステンレス株式会社 | Hot-rolled ferritic stainless-steel plate, process for producing same, and steel strip |
| JP2016191150A (en) * | 2015-03-30 | 2016-11-10 | 新日鐵住金ステンレス株式会社 | Stainless steel sheet excellent in toughness and production method thereof |
| WO2018074164A1 (en) * | 2016-10-17 | 2018-04-26 | Ｊｆｅスチール株式会社 | Hot-rolled and annealed ferritic stainless steel sheet and method for producing same |
| WO2018199062A1 (en) * | 2017-04-27 | 2018-11-01 | Ｊｆｅスチール株式会社 | Hot-rolled and annealed ferritic stainless steel sheet, and method for manufacturing same |
| WO2019087761A1 (en) * | 2017-10-30 | 2019-05-09 | Ｊｆｅスチール株式会社 | Ferritic stainless-steel sheet and method for manufacturing same |
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| JP3231174B2 (en) * | 1993-10-18 | 2001-11-19 | 新日本製鐵株式会社 | Hot-rolled high-strength steel sheet with good drawability and method for producing the same |
| JP2003213376A (en) * | 2002-01-15 | 2003-07-30 | Nisshin Steel Co Ltd | Ferritic stainless steel sheet having excellent secondary hole enlargementability and production method therefor |
| JP3886933B2 (en) * | 2003-06-04 | 2007-02-28 | 日新製鋼株式会社 | Ferritic stainless steel sheet excellent in press formability and secondary workability and manufacturing method thereof |
| JP4749888B2 (en) * | 2006-02-22 | 2011-08-17 | 新日鐵住金ステンレス株式会社 | Ferritic stainless steel sheet excellent in formability with less rough processing and manufacturing method thereof |
| JP5225620B2 (en) * | 2006-07-04 | 2013-07-03 | 新日鐵住金ステンレス株式会社 | Low chromium-containing stainless steel excellent in corrosion resistance of heat-affected zone multiple times and its manufacturing method |
| JP5045050B2 (en) * | 2006-10-05 | 2012-10-10 | Ｊｆｅスチール株式会社 | Ferritic stainless hot rolled steel sheet for cold rolling and method for producing the same |
| JP5196807B2 (en) * | 2007-02-26 | 2013-05-15 | 新日鐵住金ステンレス株式会社 | Ferritic stainless steel sheet excellent in formability with low roughness of processing surface and method for producing the same |
| CN102041452A (en) * | 2009-10-23 | 2011-05-04 | 宝山钢铁股份有限公司 | Medium chromium ferrite stainless steel and making method thereof |
| JP6765287B2 (en) * | 2016-11-17 | 2020-10-07 | 日鉄ステンレス株式会社 | Ferritic stainless steel, its manufacturing method, and fuel cell components |
-
2019
- 2019-09-25 MX MX2021004713A patent/MX2021004713A/en unknown
- 2019-09-25 JP JP2020506852A patent/JP7038799B2/en active Active
- 2019-09-25 CA CA3114743A patent/CA3114743C/en active Active
- 2019-09-25 US US17/286,657 patent/US20210363604A1/en active Pending
- 2019-09-25 KR KR1020237031897A patent/KR20230142630A/en active Application Filing
- 2019-09-25 KR KR1020217011576A patent/KR20210064281A/en not_active IP Right Cessation
- 2019-09-25 WO PCT/JP2019/037430 patent/WO2020084987A1/en active Application Filing
- 2019-09-25 CN CN201980069792.9A patent/CN112888802A/en active Pending
- 2019-10-17 TW TW108137507A patent/TWI718712B/en active
Patent Citations (5)
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| WO2014157576A1 (en) * | 2013-03-27 | 2014-10-02 | 新日鐵住金ステンレス株式会社 | Hot-rolled ferritic stainless-steel plate, process for producing same, and steel strip |
| JP2016191150A (en) * | 2015-03-30 | 2016-11-10 | 新日鐵住金ステンレス株式会社 | Stainless steel sheet excellent in toughness and production method thereof |
| WO2018074164A1 (en) * | 2016-10-17 | 2018-04-26 | Ｊｆｅスチール株式会社 | Hot-rolled and annealed ferritic stainless steel sheet and method for producing same |
| WO2018199062A1 (en) * | 2017-04-27 | 2018-11-01 | Ｊｆｅスチール株式会社 | Hot-rolled and annealed ferritic stainless steel sheet, and method for manufacturing same |
| WO2019087761A1 (en) * | 2017-10-30 | 2019-05-09 | Ｊｆｅスチール株式会社 | Ferritic stainless-steel sheet and method for manufacturing same |
Also Published As
| Publication number | Publication date |
|---|---|
| TWI718712B (en) | 2021-02-11 |
| US20210363604A1 (en) | 2021-11-25 |
| CA3114743C (en) | 2023-03-07 |
| CA3114743A1 (en) | 2020-04-30 |
| JP7038799B2 (en) | 2022-03-18 |
| TW202020182A (en) | 2020-06-01 |
| MX2021004713A (en) | 2021-06-04 |
| KR20230142630A (en) | 2023-10-11 |
| KR20210064281A (en) | 2021-06-02 |
| CN112888802A (en) | 2021-06-01 |
| JPWO2020084987A1 (en) | 2021-02-15 |
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