WO2014148540A1 - Clad steel plate having as mating material duplex stainless steel having good linear heating performance, and method for manufacturing same - Google Patents
Clad steel plate having as mating material duplex stainless steel having good linear heating performance, and method for manufacturing same Download PDFInfo
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- WO2014148540A1 WO2014148540A1 PCT/JP2014/057501 JP2014057501W WO2014148540A1 WO 2014148540 A1 WO2014148540 A1 WO 2014148540A1 JP 2014057501 W JP2014057501 W JP 2014057501W WO 2014148540 A1 WO2014148540 A1 WO 2014148540A1
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- less
- stainless steel
- duplex stainless
- steel
- clad
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 129
- 239000010959 steel Substances 0.000 title claims abstract description 129
- 239000000463 material Substances 0.000 title claims abstract description 110
- 229910001039 duplex stainless steel Inorganic materials 0.000 title claims abstract description 87
- 238000010438 heat treatment Methods 0.000 title claims description 83
- 238000004519 manufacturing process Methods 0.000 title claims description 25
- 230000013011 mating Effects 0.000 title abstract description 5
- 238000000034 method Methods 0.000 title description 17
- 239000011651 chromium Substances 0.000 claims abstract description 57
- 238000001556 precipitation Methods 0.000 claims abstract description 53
- 150000004767 nitrides Chemical class 0.000 claims abstract description 41
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 26
- 239000002244 precipitate Substances 0.000 claims abstract description 24
- 229910001566 austenite Inorganic materials 0.000 claims abstract description 20
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 19
- 238000004458 analytical method Methods 0.000 claims abstract description 10
- 238000000605 extraction Methods 0.000 claims abstract description 7
- 238000005520 cutting process Methods 0.000 claims abstract description 4
- 239000002648 laminated material Substances 0.000 claims description 31
- 238000001816 cooling Methods 0.000 claims description 23
- 229910000851 Alloy steel Inorganic materials 0.000 claims description 14
- 229910000975 Carbon steel Inorganic materials 0.000 claims description 11
- 239000010962 carbon steel Substances 0.000 claims description 11
- 229910052759 nickel Inorganic materials 0.000 claims description 9
- 229910052757 nitrogen Inorganic materials 0.000 claims description 9
- 239000012535 impurity Substances 0.000 claims description 7
- 229910052717 sulfur Inorganic materials 0.000 claims description 7
- 229910052748 manganese Inorganic materials 0.000 claims description 6
- 229910052758 niobium Inorganic materials 0.000 claims description 6
- 229910052760 oxygen Inorganic materials 0.000 claims description 6
- 229910052698 phosphorus Inorganic materials 0.000 claims description 6
- 229910052782 aluminium Inorganic materials 0.000 claims description 5
- 229910052750 molybdenum Inorganic materials 0.000 claims description 4
- 229910052720 vanadium Inorganic materials 0.000 claims description 4
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 229910052719 titanium Inorganic materials 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 2
- 238000012545 processing Methods 0.000 abstract description 2
- 238000005260 corrosion Methods 0.000 description 77
- 230000007797 corrosion Effects 0.000 description 76
- 239000000243 solution Substances 0.000 description 33
- 238000005098 hot rolling Methods 0.000 description 28
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 20
- 230000007423 decrease Effects 0.000 description 18
- 230000000694 effects Effects 0.000 description 13
- 239000000126 substance Substances 0.000 description 13
- 229910045601 alloy Inorganic materials 0.000 description 11
- 239000000956 alloy Substances 0.000 description 11
- 230000006866 deterioration Effects 0.000 description 11
- 238000005096 rolling process Methods 0.000 description 11
- CXOWYMLTGOFURZ-UHFFFAOYSA-N azanylidynechromium Chemical compound [Cr]#N CXOWYMLTGOFURZ-UHFFFAOYSA-N 0.000 description 9
- 229910052761 rare earth metal Inorganic materials 0.000 description 9
- 229910001220 stainless steel Inorganic materials 0.000 description 9
- 239000010935 stainless steel Substances 0.000 description 9
- 230000001965 increasing effect Effects 0.000 description 8
- 239000011572 manganese Substances 0.000 description 8
- 229910000859 α-Fe Inorganic materials 0.000 description 8
- 239000000203 mixture Substances 0.000 description 6
- 230000002829 reductive effect Effects 0.000 description 6
- 206010070834 Sensitisation Diseases 0.000 description 5
- 230000008313 sensitization Effects 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 3
- 238000005452 bending Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 238000010191 image analysis Methods 0.000 description 3
- 229910000765 intermetallic Inorganic materials 0.000 description 3
- 238000007670 refining Methods 0.000 description 3
- 238000004781 supercooling Methods 0.000 description 3
- 229910000997 High-speed steel Inorganic materials 0.000 description 2
- 229910000617 Mangalloy Inorganic materials 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- VNTLIPZTSJSULJ-UHFFFAOYSA-N chromium molybdenum Chemical compound [Cr].[Mo] VNTLIPZTSJSULJ-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 238000000866 electrolytic etching Methods 0.000 description 2
- 230000002708 enhancing effect Effects 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- 229910052747 lanthanoid Inorganic materials 0.000 description 2
- 150000002602 lanthanoids Chemical class 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 238000003303 reheating Methods 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 239000002436 steel type Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 1
- OKIZCWYLBDKLSU-UHFFFAOYSA-M N,N,N-Trimethylmethanaminium chloride Chemical compound [Cl-].C[N+](C)(C)C OKIZCWYLBDKLSU-UHFFFAOYSA-M 0.000 description 1
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 1
- 239000011976 maleic acid Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000010408 sweeping Methods 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 1
- 238000009849 vacuum degassing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B3/02—Rolling special iron alloys, e.g. stainless steel
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B15/00—Layered products comprising a layer of metal
- B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
- B32B15/011—Layered products comprising a layer of metal all layers being exclusively metallic all layers being formed of iron alloys or steels
-
- 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
- C21D6/02—Hardening by precipitation
-
- 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
-
- 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
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
-
- 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
-
- 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
- C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
-
- 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
-
- 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
-
- 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
-
- 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
-
- 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
-
- 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
-
- 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
-
- 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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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/38—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling sheets of limited length, e.g. folded sheets, superimposed sheets, pack rolling
- B21B2001/383—Cladded or coated products
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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
- C21D2211/001—Austenite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/004—Dispersions; Precipitations
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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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
- C21D2251/00—Treating composite or clad material
- C21D2251/02—Clad material
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Definitions
- the present invention relates to a clad steel plate using a duplex stainless steel with good linear heatability as a laminated material and a method for producing the same.
- the present invention also relates to an inexpensive alloy element-saving duplex stainless steel clad steel sheet that does not require solution heat treatment and a method for producing the same. More specifically, the present invention relates to a clad steel plate made of a duplex stainless steel that can be used as a tank for a transport ship, etc., and is one of the important issues when applied to the application.
- the present invention relates to a clad steel plate using a duplex stainless steel as a laminated material and a method for producing the same, which suppresses a decrease in corrosion resistance due to state heating and thereby makes application to the application superior.
- Duplex stainless steel has both austenite and ferrite phases in the steel structure, and has been used for petrochemical equipment materials, pump materials, chemical tank materials, etc. as a high-strength, high-corrosion-resistant material. Yes. Furthermore, since duplex stainless steel is generally a low Ni component system, it has a lower alloy cost and less variation than the austenitic stainless steel, which is the mainstream of stainless steel, due to the recent rise in metal raw materials. Has attracted attention as.
- the alloy-saving type is a steel type in which the content of an alloy that is more expensive than the conventional duplex stainless steel is suppressed, and the merit that the alloy cost is lower than that of the austenitic steel is further increased.
- Steel types disclosed in Patent Document 1 and the like correspond to alloy-saving types.
- the steel of Patent Document 1 is standardized by ASTM-A240 as S32101 (representative component 22Cr-1.5Ni-5Mn-0.22N).
- the corrosion resistance is reduced to a level close to that of SUS316L or SUS304 as compared with the conventional duplex stainless steel, but Mo is almost 0 and Ni is substantially reduced to about 1%.
- Patent Document 2 discloses that C: 0.06% or less, Si: 0.1 to 1.5%, Mn: 2.0 to 4.0%, P: 0.05% or less S: 0.005% or less, Cr: 19.0 to 23.0%, Ni: 1.00 to 4.0%, Mo: 1.0% or less, Cu: 0.1 to 3.0%, V: 0.05 to 0.5%, Al: 0.003 to 0.050%, O: 0.007% or less, N: 0.10 to 0.25%, Ti: 0.05% or less
- the balance is Fe and inevitable impurities
- the Md 30 value is 80 or less
- the upper limit of the N content is Ni-bal.
- the austenite phase area ratio is 40 to 70% and 2 ⁇ Ni + Cu is 3.5 or more. Alloy-saving two-phase with good corrosion resistance and toughness of weld heat affected zone Stainless steel has been disclosed.
- the duplex stainless steel described in Patent Document 2 is a steel that can suppress a decrease in corrosion resistance caused by precipitation of chromium nitride in a weld heat affected zone, which is a problem in an alloy-saving duplex stainless steel.
- the point of Patent Document 2 is that Ni-bal. Is to define an upper limit of N according to.
- a clad steel sheet is a hot-rolled steel material that can provide composite properties economically by providing corrosion resistance to stainless steel used as a laminated material and providing the base material with strength, toughness and weldability. It is.
- Many chemical tankers which are one type of tanks for transport ships, have stainless steel tanks for loading and transporting various chemical products.
- the outside of the tank is a carbon steel outer shell, and a stainless clad steel plate is often used for the tank because of its weldability.
- austenitic stainless steel has often been used as a laminated material.
- austenitic stainless steel has often been used as a laminated material.
- Duplex stainless steel contains a large amount of Cr, Mo, Ni, and N, and intermetallic compounds and nitrides are likely to precipitate. Therefore, in a normal hot-rolled steel manufacturing method, precipitation occurs by solution heat treatment at 1000 ° C or higher. A step of dissolving the product is essential. However, if solution heat treatment is performed in the manufacturing process of the clad steel plate, the toughness of the base carbon steel is lowered, so that it is not preferable in terms of the use of the clad steel plate. Further, in addition to cost reduction as the original aim of using a clad steel plate, it is desired that solution heat treatment be omitted in the production process of the clad steel plate because of the recent demand for reduction of energy used.
- a carbon steel whose chemical composition is devised so that mechanical properties can be ensured by heat treatment at a high temperature of 1000 ° C. or higher on the premise of addition of heat treatment is used as a base material (eg, Patent Document 3).
- a base material eg, Patent Document 3
- heat treatment is omitted to manufacture a duplex stainless steel clad steel sheet (Patent Document 4, etc.), or reheating during hot rolling to suppress precipitation of carbides and the like in the laminated material. (Patent Document 5, etc.) and the like have been taken.
- Patent Document 4 duplex stainless steel clad steel sheet
- Patent Document 5 etc. reheating during hot rolling to suppress precipitation of carbides and the like in the laminated material.
- the inventors of the present invention disclosed in Patent Document 6 that the duplex stainless steel laminated material is, by mass%, C: 0.03% or less, Si: 0.05 to 1.0%, Mn: 0.5 to 7 0.0%, S: 0.010% or less, Ni: 0.1-5.0%, Cr: 18.0-25.0%, N: 0.05-0. 30%, Al: 0.001 to 0.05%, and having a chromium nitride precipitation temperature TN of 800 to 970 ° C. serving as an index for chromium nitride precipitation during hot rolling.
- a clad steel plate made of phase stainless steel.
- the inventors of the present invention have both the toughness of the base material and the corrosion resistance of the alloy element-saving duplex stainless steel combined material. A method for manufacturing a steel sheet was provided.
- a duplex stainless steel that is an alloy-saving type (hereinafter also simply referred to as an alloy-saving duplex stainless steel) is used as an alternative to a tank made of SUS304 that is used for a product of a relatively mild corrosive environment among chemical tankers.
- a problem in application is a reduction in corrosion resistance due to linear heating.
- the linear heating is a technique for performing bending by sweeping a burner and heating in a linear manner when processing a steel material for tanks, and is heated up to about 1000 ° C. depending on the place. When this linear heating is applied to S32101 or the like, the precipitation of nitrides occurs, so that the corrosion resistance of the heating part decreases.
- the present inventors have disclosed a duplex stainless steel having a good linear heating property.
- duplex stainless steel clad steel plate In order to apply the duplex stainless steel clad steel plate to the chemical tanker, it is required to omit the solution heat treatment during the production of the clad steel plate as described above and to improve the linear heatability. In order to achieve these, it was thought that the duplex stainless steel disclosed in Patent Document 7 and excellent in linear heatability may be the clad steel disclosed in Patent Document 6. However, when the present inventors tried, it was found that there was a case where sufficient duplex heating could not be provided by simply applying the duplex stainless steel of Patent Document 7 to the clad steel plate. This is because, as will be described later, when the clad steel sheet without the solution heat treatment is linearly heated, it passes through the corrosion resistance lowering temperature range twice, and the corrosion resistance lowers more easily.
- the present invention has been made in view of the above-mentioned facts, and its purpose is to suppress the alloy cost as much as possible and to omit the solution heat treatment and to suppress the corrosion resistance decrease during the linear heating. It is an object to provide a clad steel plate using a cheap inexpensive duplex stainless steel as a laminated material and a method for producing the same.
- the present inventors considered finding a solution by using, as a laminated material of clad steel plates, a component system in which a nitride is difficult to precipitate in an alloy-saving duplex stainless steel.
- the steel materials shown in Patent Document 2 and Patent Document 7 are steel materials that suppress nitride precipitation in order to suppress deterioration in characteristics of the weld heat affected zone. Therefore, the following experiment was conducted by applying such steel materials and steel materials of peripheral components.
- the heating temperature of the hot rolling is 1150 to 1250 ° C.
- the entry temperature of the final finishing rolling pass of the hot rolling and the subsequent cooling rate are changed, respectively.
- a hot-rolled clad steel material having a thickness in the range of 10 mm to 35 mm, of which the thickness of the laminated material was 3 mm was obtained.
- the present inventors performed a heat treatment corresponding to linear heating on the hot-rolled clad steel material, and then performed corrosion resistance evaluation and analysis of precipitates. As a result, it was found that the steel material having good corrosion resistance can be distinguished by the precipitate analysis.
- the inventors have found that in order to ensure the corrosion resistance equivalent to or higher than that of SUS304, the component system should be compensated for the decrease in corrosion resistance due to precipitation sensitization.
- the present invention has been completed, in which the condition of good linear heatability is clearly specified for a clad steel plate that uses alloy-saving duplex stainless steel as a laminated material and omits solution heat treatment.
- the gist of the present invention is as follows. [1] A clad steel plate using a duplex stainless steel as a base material, a carbon steel or an alloy steel as a base material, wherein the duplex stainless steel is C: 0.03% or less in terms of mass%, Si: 0 0.1 to 1.0%, Mn: 1.0 to 7.0%, P: 0.05% or less, S: 0.005% or less, Cr: 20.5 to 24.0%, Ni: 1.
- the calculated Cr nitride precipitation start temperature Npre shown by the formula is 920 ° C. or lower, and after isothermal heat treatment at 700 ° C. for 3 minutes, A duplex stainless steel with good linear heatability, characterized in that the amount of chromium in the precipitate obtained by cutting out only the laminated material from the steel plate and conducting an electrolytic extraction residue analysis is 0.05% or less.
- each element name represents its content (% by mass).
- 0 is substituted for elements not contained in the steel.
- Nb is 0.02 to 0.15% and Nb ⁇ N is 0.003 to 0.015 (where Nb and N are the respective contents)
- a clad steel sheet comprising a duplex stainless steel with good linear heatability, characterized in that it is contained so as to be a mass% of [3]
- Ca 0.0050% or less, Mg: 0.0050% or less, REM: 0.050% or less
- B 0.0040%
- a clad steel sheet comprising a duplex stainless steel with good linear heatability characterized by containing one or more of the following: [4]
- duplex stainless steel In the duplex stainless steel according to any one of the above [1] to [4], Ti: 0.05% or less in mass%. W: 1.0% or less, Sn: A clad steel plate comprising a duplex stainless steel with good linear heatability, characterized by containing one or more of 0.1% or less.
- a method for producing a clad steel plate made of a duplex stainless steel with good heatability A method for producing a clad steel plate made of a duplex stainless steel with good heatability.
- a clad steel plate using alloy-saving type duplex stainless steel as a combination material and carbon steel or alloy steel as a base material it is one of the major problems when applied to a tank for transportation and the like. It becomes possible to suppress a decrease in corrosion resistance during linear heating. As a result, application to, for example, a chemical tanker can be realized, and a clad steel plate made of a duplex stainless steel in which alloy elements are reduced compared to conventional steel can be manufactured at low cost with less energy. For this reason, the place which the clad steel plate of this invention and its manufacturing method contribute to an industrial surface and an environmental surface is very large.
- the clad steel plate according to the present embodiment will be described in detail below. In addition,% about a component means the mass% unless there is particular notice.
- the clad steel plate which uses the duplex stainless steel of this embodiment as a laminated material is demonstrated in detail.
- the clad steel plate comprising the duplex stainless steel according to the present embodiment is a clad steel plate comprising the duplex stainless steel as a laminate, carbon steel or alloy steel as a base material, and the duplex stainless steel has a mass.
- % C: 0.03% or less, Si: 0.1 to 1.0%, Mn: 1.0 to 7.0%, P: 0.05% or less, S: 0.005% or less, Cr: 20.5 to 24.0%, Ni: 1.5 to 5.0%, V: 0.05 to 0.5%, Al: 0.003 to 0.050%, O: 0.007%
- N 0.10 to 0.25%
- Mo 1.0% or less and / or Cu: 2.0% or less
- the phase area ratio is 40 to 70%
- the Cr nitride precipitation start temperature calculation value Npre represented by the following formula (1) is The temperature is 20 ° C. or less, and after the isothermal heat treatment at 700 ° C.
- each element name represents its content (%). For elements not contained in steel, 0 is substituted. Below, the reason for limitation of the component of the laminated material (duplex stainless steel) in the clad steel plate which uses the duplex stainless steel which concerns on this embodiment as a laminated material is demonstrated.
- ⁇ C 0.03% or less>
- the C content is limited to 0.03% or less in order to ensure the corrosion resistance of the duplex stainless steel.
- C exceeds 0.03%, Cr carbide is generated during hot rolling, so that corrosion resistance and toughness deteriorate.
- the preferable C content is 0.025% or less, and more preferably 0.022% or less.
- it is preferably 0.001% or more, and more preferably 0.010% or more.
- Si 0.1 to 1.0%> Si is added in an amount of 0.1% or more for deoxidation. However, when Si exceeds 1.0%, toughness deteriorates. Therefore, the upper limit is made 1.0%. From this viewpoint, the preferable range of the Si content is 0.2 to 0.5%.
- Mn increases the austenite phase in the duplex stainless steel, increases the solid solubility of nitrogen, and suppresses the precipitation of Cr nitride, so 1.0% or more is added. However, if Mn is added over 7.0%, the corrosion resistance of the rolled material deteriorates. Therefore, the upper limit is set to 7.0%.
- a preferred range is 2.0 to 4.0%, and a more preferred range is more than 2.0% to less than 3.0%.
- ⁇ P: 0.05% or less> ⁇ S: 0.005% or less> P is an element that is inevitably mixed from the raw material, and deteriorates hot workability and toughness. Therefore, the content is preferably as small as possible, and is limited to 0.05% or less. A preferable P content is 0.03% or less. In addition, since excessive reduction leads to the increase in refining cost, it is preferable to make a minimum into 0.005%. S is an element that is inevitably mixed from the raw material and degrades hot workability, toughness, and corrosion resistance. Therefore, the content is preferably as small as possible, and is limited to 0.005% or less. A preferable S content is 0.0020% or less. In addition, since excessive reduction leads to the increase in refining cost, it is preferable to make a minimum into 0.0002%.
- Cr is an element basically necessary for ensuring corrosion resistance, and is a relatively inexpensive alloy.
- Cr is a ferrite-forming element, and excessive addition promotes the formation of Cr nitride. Therefore, if the content exceeds 24.0%, it becomes difficult to secure austenite.
- the Cr content is set to 20.5% or more and 24.0% or less. From these viewpoints, the preferable range of the Cr content is 21.0 to less than 23.0%.
- Ni is an element effective for increasing the austenite phase in the duplex stainless steel, improving the toughness of the ferrite phase, and further improving the corrosion resistance against various acids, and is effective for reducing Npre described later. Element. From this point of view, Ni is added in an amount of 1.5% or more. However, since it is an expensive alloy, it is suppressed as much as possible to 5.0% or less in the present invention. A preferable range is 2.0 or more and less than 4.0%.
- Mo is a very effective element that greatly enhances the corrosion resistance of stainless steel, but since it is a very expensive element, its content is defined as 1.0% or less. In consideration of the balance between corrosion resistance and cost, the preferable range of the Mo content is 0.1 to less than 0.5%.
- Cu is an element effective for increasing the austenite phase in the duplex stainless steel and improving the toughness of the ferrite phase as well as Ni, and further improving the corrosion resistance against various acids, as compared to Ni. Since it is an inexpensive alloy, it is preferable to contain 0.5% or more. However, if the content exceeds 2.0%, nitride precipitation is promoted and Npre described later is increased, so the upper limit of the Cu content is set to 2.0%. A preferred upper limit is 1.2%.
- V is an element that can suppress the precipitation of Cr nitride by addition of a small amount. That is, since V has a higher affinity with nitrogen than Cr, if the V content is kept at a solid solution level, the activity of N can be lowered and the precipitation of Cr nitride can be delayed. For that purpose, addition of 0.05% or more is necessary. On the other hand, if added over 0.5%, the toughness decreases due to precipitation of V nitride, so the upper limit is made 0.5%. From these viewpoints, the preferable range of the V content is 0.06% to 0.30%.
- Al is an important element for deoxidation of steel, and it is necessary to contain 0.003% or more in order to reduce oxygen in the steel. In consideration of the refining cost, it is preferable to set it to 0.010% or more.
- Al is an element having a relatively large affinity with N, and if added excessively, AlN is generated and the toughness of the base material is inhibited. The degree depends on the N content, but if Al exceeds 0.050%, the toughness deteriorates remarkably, so the upper limit of the content is set to 0.050%. Preferably it is 0.030% or less.
- O is a harmful element constituting an oxide that is representative of nonmetallic inclusions, and excessive inclusion inhibits toughness.
- the upper limit of O is 0.007%. Preferably it is 0.005% or less.
- the lower limit is preferably set to 0.0005%.
- N is an effective element for increasing the austenite phase in the duplex stainless steel while increasing the strength and corrosion resistance by dissolving in the austenite phase. In particular, it is effective for enhancing the corrosion resistance of the austenite phase. For this reason, N is contained 0.10% or more. On the other hand, if the content exceeds 0.25%, precipitation of Cr nitride is promoted, so the upper limit of the content is made 0.25%. From the viewpoint of improving the corrosion resistance and suppressing the precipitation of Cr nitride, the preferable content of N is 0.13 to 0.20%.
- Nb is 0.02 to 0.15% and Nb ⁇ N is 0.003 to 0.015 (where Nb and N are the mass% of the respective contents) It is preferable to add so that it represents.
- Nb like V, is an element that is effective in reducing the N activity and suppressing nitride precipitation, so it is selectively added.
- the affinity with N is relatively high and Nb nitride precipitates even when added in a small amount, it must be handled with care. Therefore, in the case of adding Nb, the effect of suppressing the nitride of V is obtained by adding up to the upper limit determined by the relational expression with N (the following formula (2)) so that the addition is below the solid solubility limit.
- Nb is preferably added in an amount of 0.02% or more.
- the amount of Nb added is preferably 0.15% or less, and more preferably 0.08% or less.
- Nb is added so that a value according to the following equation (2) for obtaining a so-called solid solubility product is 0.003 to 0.015.
- Ca 0.0050% or less
- Mg 0.0050% or less
- REM 0.050% or less
- B One or more of 0.0040% or less may be selectively added as necessary.
- the upper limit of the content is determined as follows.
- the upper limit of Ca and Mg is 0.0050%
- the upper limit of B is 0.0040%
- the upper limit of REM is 0.050%.
- Preferred contents for B and Ca are 0.0005 to 0.0030%
- REM 0.005 to 0.050%.
- REM is the total content of lanthanoid rare earth elements such as La and Ce.
- Co is an element effective for enhancing the toughness and corrosion resistance of the duplex stainless steel, and is selectively added.
- the Co content is preferably 0.02% or more.
- Co is contained exceeding 1.0%, Co is an expensive element and an effect commensurate with the cost cannot be exhibited, so the upper limit is set to 1.0%.
- a preferable content when Co is added is 0.02 to 0.5%.
- Ti 0.05% or less
- W 1.0% or less
- Sn 0.1% or less
- Ti can suppress the adverse effect on corrosion resistance due to C and S by addition, but if added excessively, adverse effects such as a decrease in toughness occur. Therefore, the content when Ti is selectively added is preferably limited to 0.05% or less, more preferably 0.02% or less.
- W is an element that is selectively added to additionally enhance the corrosion resistance of the duplex stainless steel, but is an expensive element and excessive addition causes an increase in cost. Therefore, the W content is preferably limited to 1.0% or less, more preferably 0.8% or less.
- Sn is a selective element that additionally improves acid resistance, and Sn can be added up to 0.1% from the viewpoint of hot workability.
- the upper limit is more preferably 0.08% or less.
- preferable content which exhibits the said effect of Ti, W, and Sn stably is 0.001% or more, 0.05% or more, and 0.05% or more, respectively.
- the austenite phase area ratio needs to be in the range of 40 to 70%. If it is less than 40%, the problem of poor toughness occurs. On the other hand, if it exceeds 70%, problems of hot workability and stress corrosion cracking appear. In addition, when the austenite phase is too small or too large, the corrosion resistance becomes poor. In consideration of the balance of the above-mentioned characteristics, the austenite phase area ratio is preferably 45 to 65%.
- the Cr nitride precipitation start temperature calculation value Npre shown in the following formula (1) is set to 920 ° C. or less.
- Npre 12Cr + 50Si + 36Mo-20Ni-15Mn + 28Cu + 470N-290C + 620
- the magnitude of the precipitation driving force is considered to correspond to the magnitude of the degree of supercooling indicated by the difference between the precipitation start temperature and the actual temperature.
- the present inventors obtain the precipitation start temperature by simulation calculation, formulate the magnitude of contribution of each component to Cr nitride precipitation, and use this to define the component range where Cr nitride is difficult to precipitate. Tried to do. Specifically, the influence of the additive element was calculated by simulation calculation using thermodynamic data, and the influence of the additive element was confirmed by experiment, and the above formula (1) was created. Furthermore, from the correspondence between the value calculated by this formula (1) and the experimental results of corrosion resistance, when Npre is 920 ° C. or less, it is confirmed that the corrosion resistance decrease due to heat treatment at 700 ° C. ⁇ 3 minutes can be substantially suppressed, This provision was adopted.
- the clad steel plate according to the present embodiment is a clad steel plate using the above-described duplex stainless steel as a combination material and carbon steel or alloy steel as a base material.
- the base material of the clad steel plate has a higher C content than the duplex stainless steel used as a laminated material.
- ordinary steel (carbon steel) or alloy steel is used, but also in this embodiment, the material of the base material can be appropriately selected and used according to the intended use, and is not particularly limited.
- the alloy steel is preferably one excluding stainless steel, and includes one or more selected from the group consisting of low alloy steel, nickel steel, manganese steel, chromium molybdenum steel, and high speed steel. However, it is not limited to these.
- the duplex stainless steel according to this embodiment is a laminated material (duplex stainless steel) after being subjected to an isothermal heat treatment at 700 ° C. for 3 minutes as a characteristic index capable of suppressing a decrease in corrosion resistance during linear heating. It is characterized by the fact that the chromium content in the precipitate obtained by cutting out only this and conducting the electrolytic extraction residue analysis is 0.05% or less.
- the vicinity of 700 ° C. is a temperature range in which chromium nitride is precipitated in the largest amount, and 3 minutes is defined as the maximum level of time that is exposed to the temperature range by linear heating.
- the present inventors determined the amount of chromium in the precipitate by the following procedure (electrolytic extraction residue analysis method), but the measurement of the amount of chromium is not limited to this procedure, and a similar method may be used.
- (1) Take out only the laminated material from the specimen after the isothermal heat treatment at 700 ° C. for 3 minutes, and polish the surface with # 500.
- (2) A 3 g sample is taken and electrolyzed (100 mV vs SCE constant potential electrolysis) in a non-aqueous solution (3% maleic acid + 1% tetramethylammonium chloride + remaining methanol) to dissolve the matrix.
- the manufacturing method of the clad steel plate according to the present embodiment uses the duplex stainless steel of the present embodiment described above as a combined material, and a rolled material obtained by combining the combined material and a base material made of ordinary steel or alloy steel. , Hot-rolled at 900 ° C. or higher, and at the time of subsequent cooling, the passing time from 900 to 600 ° C. is 60 seconds or longer and within 15 minutes. Clad steel plate).
- Hot-rolled at 900 ° C. or higher, and at the time of subsequent cooling, the passing time from 900 to 600 ° C. is 60 seconds or longer and within 15 minutes. Clad steel plate).
- the clad steel plate of this embodiment is manufactured by the following processes. First, a base material having a predetermined thickness and a laminated material made of the duplex stainless steel according to the above-described embodiment are prepared, and the respective joint surfaces are cleaned and overlapped, and four rounds (the outer circumference of the superposed surface). Are joined by welding to slab (rolled material). At this time, vacuum degassing or the like may be performed as appropriate in order to increase the bonding strength of the overlapping surfaces.
- the base material ordinary steel (carbon steel) or alloy steel is used, but as described above, the material of the base material can be appropriately selected and used according to the intended use, and is not particularly limited.
- the alloy steel preferably excludes stainless steel, and includes one or more selected from the group consisting of low alloy steel, nickel steel, manganese steel, chromium molybdenum steel, and high speed steel.
- the material heating step is a step of reheating the slab in order to perform hot rolling, and the heating temperature is not particularly limited, but should be 1000 to 1200 ° C. from the viewpoint of securing the rolling temperature and cost. Is preferred.
- the temperature history of this hot rolling is an important factor with respect to the regulation of the manufacturing conditions of the clad steel sheet in the present invention.
- the hot rolling temperature that is, the hot rolling finishing temperature is set to 900 ° C. or higher. Thereby, precipitation of the nitride at the time of hot rolling can be suppressed in the duplex stainless steel which is the laminated material of the present embodiment.
- the passing time in the range of 900 to 600 ° C. is set to 60 seconds or more and 15 minutes or less.
- This temperature range of 900 ° C. to 600 ° C. is the temperature range where the precipitation rate of nitride is the fastest.
- the corrosion resistance decrease due to the precipitation and sensitization of nitrides at the time of the cooling becomes a level that cannot be ignored.
- rapid cooling with a passage time of less than 60 seconds no precipitation occurred at that time, but it was found that precipitation was promoted by heat treatment at 700 ° C. for 3 minutes.
- Nitride may be precipitated by heating to about 0 ° C. It is presumed that this is because many dislocations generated during rolling remain due to rapid cooling after hot rolling, and these become precipitation nuclei during heat treatment at 700 ° C. for 3 minutes corresponding to linear heating. That is, in the manufacturing method according to the present embodiment, during cooling after hot rolling, nitrides are most likely to precipitate (the precipitation rate is fast), and the passing time in the temperature range of 900 to 600 ° C. is within 60 seconds to 15 minutes.
- the corrosion resistance can be improved as the passage time is shorter than 60 seconds, it is preferably 5 minutes or less, more preferably 3 minutes or less.
- the clad steel plate according to this embodiment can be manufactured.
- the clad steel sheet laminated material (duplex stainless steel) obtained by the method according to the present embodiment generates precipitates during linear heating, steel component control, precipitation driving force control, and cooling. This is prevented by suppressing precipitates at the stage. For this reason, the solution treatment applied to a normal hot rolled steel material can be omitted. As a result, it is possible to reduce manufacturing costs and energy used during manufacturing.
- Table 1 shows the chemical composition (mass%) of the laminated material.
- REM means a lanthanoid rare earth element, and the content indicates the total of these elements.
- P, S, and O are inevitable impurities, but in the present example, they were limited to the numerical range shown in Table 1.
- the clad steel plate is made of a duplex stainless steel having the chemical composition shown in Table 1, with C: 0.16%, Si: 0.21%, Mn: 0.63%, P: 0.018%, S : SS6 steel having a composition consisting of 0.006%, Ni: 0.01%, Cr: 0.04%, Cu: 0.02%, the balance Fe and unavoidable impurities, with a predetermined thickness
- a material to be rolled was used.
- As the material to be rolled a base material and a mating material were assembled by welding to form a slab having a total thickness of 130 mm after assembling the mating material and the base material. This slab was used as a material for hot rolling (a material to be rolled).
- a clad steel plate was prepared by a two-stage rolling mill after heating to a predetermined temperature of 1150 to 1220 ° C. with the laminated material side of the material to be rolled as the lower surface.
- the rolling is repeated 10 to 15 times and finished in the range of 865 to 956 ° C as shown in Table 2 so that the final thickness of the material to be rolled is 10 to 35 mm.
- Rolling was performed.
- the temperature immediately before the final pass was defined as the hot rolling finishing temperature. While being transferred to a cooling bed and measuring the surface temperature of the steel sheet, it was allowed to cool or water-cooled at various water flow rates while controlling the elapsed time from 900 ° C. to 600 ° C. as shown in Table 2.
- a rolled clad steel sheet having a thickness of 3 mm was obtained.
- the obtained clad steel plate No. In each of 1 to 17 and 19 to 29, samples for solution heat treatment (solution heat treatment material) were collected, and solution heat treatment was performed at 1000 ° C. for 10 minutes. Further, the obtained clad steel plate (as-rolled), the clad steel plate (as-rolled) heat-treated at 700 ° C. for 3 minutes (also referred to as 700 ° C. ⁇ 3-minute heat-treated material or simply 700 ° C. heat-treated material), and the above.
- the laminated material was taken out from each of the solution heat treatment materials and evaluated as follows.
- the pitting potential was measured according to JIS G0577 with respect to the surface of 1 mm of the subepidermal surface of the clad steel plate (as-rolled), clad steel plate (as-rolled) heat-treated at 700 ° C. for 3 minutes, and the solution heat-treated material.
- the corrosion resistance deterioration of the material itself can be suppressed as it is rolled, there is a possibility that the corrosion resistance may vary due to the subsequent linear heat treatment (the heat treatment at 700 ° C. for 3 minutes). From this, the pitting corrosion potential after heat treatment at 700 ° C. for 3 minutes including those with as-rolled materials having a small decrease in pitting potential was measured, and the difference from the solution heat treated material was determined. If it is less than 10 V, it was determined that the deterioration of the corrosion resistance could be suppressed even in the linear heat treatment (the heat treatment at 700 ° C. for 3 minutes). Moreover, if said difference was 0.05 V or less, it evaluated as a thing with especially high corrosion-resistant deterioration inhibitory effect.
- Extraction residue analysis determined the amount of chromium in the precipitate by the method described above.
- the area ratio of the austenite phase the cross section parallel to the rolling direction is embedded and mirror-polished, and after electrolytic etching in an aqueous KOH solution, the ferrite phase area ratio is measured by performing image analysis with an optical microscope, and the rest This portion was defined as the austenite phase area ratio.
- the ferrite phase area ratio was measured by embedding a cross section parallel to the rolling direction, mirror polishing, performing electrolytic etching in a KOH aqueous solution, and then performing image analysis by observation with an optical microscope. The observation magnification was 400 times and the observation area was 3.75 mm 2 .
- the ferrite phase area was measured by a method based on ASTM E1245-03 “Standard Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis”.
- ASTM E1245-03 Standard Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis.
- three No. 4 V-notch Charpy test pieces defined in JIS Z 2242: 2005 were cut out from each direction perpendicular to the rolling direction and fractured.
- V notch was processed so as to propagate in the rolling direction, and the impact value at ⁇ 20 ° C. was measured with a tester with a maximum energy of 500 J specifications.
- the impact value was 150 J / cm 2 or less, it was evaluated that the toughness did not satisfy the standard required for practical use (poor toughness).
- No. 1 to 11, 15 and 27 to 29 are the results of the examples of the present invention.
- the amount of chromium in the precipitates remains at 0.05% or less.
- the pitting corrosion potential difference of the as-rolled material was only reduced by less than 0.10 V compared to the solution heat-treated material (solution-treated material).
- the clad steel plate as an example of the present invention has little deterioration in corrosion resistance even when subjected to linear heating. Further, No. No.
- Nos. 1, 4, 6, 8 to 11, 28, 29 have a pitting corrosion potential difference with the solution material during linear heating (pitting corrosion potential difference between the 700 ° C. heat treatment material and the solution agent) of 0.05 V or less. It can be seen that the effect of suppressing deterioration of corrosion resistance is particularly high. On the other hand, the elapsed time from 900 to 600 ° C. exceeds 3 min. 2, No. 27, no. 15 and No. When comparing 30 with each other, the effect of suppressing deterioration of corrosion resistance during linear heating (pitting corrosion potential difference between the heat-treated material at 700 ° C.
- the solution agent may be 0.05 V or less, or may be more than 0.05 V. I understand that. From the above, it has been found that when the elapsed time from 900 to 600 ° C. is 3 min or less, the effect of inhibiting the deterioration of corrosion resistance during linear heating becomes stable and good.
- no. Nos. 12 to 14, 16, 17, and 19 to 21 are comparative examples using steels having components outside the range of the present invention or having a high Npre value.
- No. 12 to 14, 16, 17, and 19 to 21 are comparative examples using steels having components outside the range of the present invention or having a high Npre value.
- No. 12 to 14, 16, 17, and 19 to 21 are comparative examples using steels having components outside the range of the present invention or having a high Npre value.
- No. 12 in No. 12 since C was high, Cr carbide was generated, and the corrosion resistance of the material was greatly reduced as it was hot rolled.
- No. No. 13 is high in Si. Since No. 16 had low Ni, toughness fell.
- No. No. 14 cannot satisfy the upper limit of Npre.
- Npre was higher than 920 ° C., the amount of chromium in the precipitate exceeded 0.05% by heating at 700 ° C. for 3 minutes, and the corrosion resistance was greatly reduced.
- no. 22 to 26 are comparative examples produced by the production method outside the scope of the present invention.
- the present invention makes it possible to obtain an inexpensive clad steel sheet having good linear heatability even when the alloy heat treatment type duplex stainless steel is used as a combined material and the solution heat treatment is omitted. It was.
- the clad steel plate and the method for producing the same it is possible to suppress a decrease in corrosion resistance during linear heating, and it is possible to produce a clad steel plate with low cost and little energy. Therefore, according to the present invention, it is possible to provide a clad steel plate suitable for a transport tank including a chemical tanker and a method for producing the same.
Abstract
In this clad steel plate, with regard to a duplex stainless steel used as the mating material for the clad steel plate, the austenite phase area ratio is 40% to 70%, the calculated value (Npre) of the precipitation starting temperature for a Cr nitride represented by formula (1) is no greater than 920ºC, and the chromium content in the precipitate obtained by performing isothermal heat processing for 3 minutes at 700ºC, and then cutting out only the mating material from the clad steel plate and performing electrolytic extraction residue analysis, is no greater than 0.05%. Npre = 12Cr + 50Si + 36Mo-20Ni-15Mn + 28Cu + 470N-290C + 620...(1)
Description
本発明は、線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板およびその製造方法に関する。また本発明は、溶体化熱処理を省略した安価な合金元素節減型二相ステンレスクラッド鋼板およびその製造方法に関する。より詳細には、本発明は、輸送船のタンク類等として使用可能な二相ステンレス鋼を合わせ材としたクラッド鋼板において、当該用途への適用の際、重要な課題の一つである、線状加熱による耐食性の低下を抑制し、それにより当該用途への適用を優位にする、二相ステンレス鋼を合わせ材とするクラッド鋼板およびその製造方法に関する。
本願は、２０１３年３月１９日に、日本に出願された特願２０１３－０５７０９２号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to a clad steel plate using a duplex stainless steel with good linear heatability as a laminated material and a method for producing the same. The present invention also relates to an inexpensive alloy element-saving duplex stainless steel clad steel sheet that does not require solution heat treatment and a method for producing the same. More specifically, the present invention relates to a clad steel plate made of a duplex stainless steel that can be used as a tank for a transport ship, etc., and is one of the important issues when applied to the application. The present invention relates to a clad steel plate using a duplex stainless steel as a laminated material and a method for producing the same, which suppresses a decrease in corrosion resistance due to state heating and thereby makes application to the application superior.
This application claims priority based on Japanese Patent Application No. 2013-057092 filed in Japan on March 19, 2013, the contents of which are incorporated herein by reference.
本願は、２０１３年３月１９日に、日本に出願された特願２０１３－０５７０９２号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to a clad steel plate using a duplex stainless steel with good linear heatability as a laminated material and a method for producing the same. The present invention also relates to an inexpensive alloy element-saving duplex stainless steel clad steel sheet that does not require solution heat treatment and a method for producing the same. More specifically, the present invention relates to a clad steel plate made of a duplex stainless steel that can be used as a tank for a transport ship, etc., and is one of the important issues when applied to the application. The present invention relates to a clad steel plate using a duplex stainless steel as a laminated material and a method for producing the same, which suppresses a decrease in corrosion resistance due to state heating and thereby makes application to the application superior.
This application claims priority based on Japanese Patent Application No. 2013-057092 filed in Japan on March 19, 2013, the contents of which are incorporated herein by reference.
二相ステンレス鋼は、鋼の組織にオーステナイト相とフェライト相の両相を持つものであり、高強度高耐食性の材料として以前から石油化学装置材料、ポンプ材料、ケミカルタンク用材料等に使用されている。更に、二相ステンレス鋼は、一般に低Ｎｉの成分系であることから、直近の金属原料高騰状況に伴い、ステンレス鋼の主流であるオーステナイト系ステンレス鋼よりも合金コストが低くかつその変動が少ない材料として注目を浴びている。
Duplex stainless steel has both austenite and ferrite phases in the steel structure, and has been used for petrochemical equipment materials, pump materials, chemical tank materials, etc. as a high-strength, high-corrosion-resistant material. Yes. Furthermore, since duplex stainless steel is generally a low Ni component system, it has a lower alloy cost and less variation than the austenitic stainless steel, which is the mainstream of stainless steel, due to the recent rise in metal raw materials. Has attracted attention as.
二相ステンレス鋼の直近のトピックとして、省合金タイプの開発とその使用量増加がある。省合金タイプとは、従来の二相ステンレス鋼より高価な合金の含有量を抑え、オーステナイト系より合金コストが低いメリットを更に増大させた鋼種である。特許文献１等に開示されている鋼種等が省合金タイプに該当する。特許文献１の鋼はＡＳＴＭ－Ａ２４０でＳ３２１０１（代表成分２２Ｃｒ－１．５Ｎｉ－５Ｍｎ－０．２２Ｎ）として規格化されている。省合金タイプの二相ステンレス鋼では、従来の二相ステンレス鋼より耐食性を下げＳＵＳ３１６ＬもしくはＳＵＳ３０４に近いレベルとした代わりに、Ｍｏをほぼ０とし、Ｎｉを約１％と大幅に低減している。
The most recent topic of duplex stainless steel is the development of an alloy-saving type and an increase in its usage. The alloy-saving type is a steel type in which the content of an alloy that is more expensive than the conventional duplex stainless steel is suppressed, and the merit that the alloy cost is lower than that of the austenitic steel is further increased. Steel types disclosed in Patent Document 1 and the like correspond to alloy-saving types. The steel of Patent Document 1 is standardized by ASTM-A240 as S32101 (representative component 22Cr-1.5Ni-5Mn-0.22N). In the alloy-saving type duplex stainless steel, the corrosion resistance is reduced to a level close to that of SUS316L or SUS304 as compared with the conventional duplex stainless steel, but Mo is almost 0 and Ni is substantially reduced to about 1%.
これに対し本発明者らは特許文献２において、Ｃ：０．０６％以下、Ｓｉ：０．１～１．５％、Ｍｎ：２．０～４．０％、Ｐ：０．０５％以下、Ｓ：０．００５％以下、Ｃｒ：１９．０～２３．０％、Ｎｉ：１．００～４．０％、Ｍｏ：１．０％以下、Ｃｕ：０．１～３．０％、Ｖ：０．０５～０．５％、Ａｌ：０．００３～０．０５０％、Ｏ：０．００７％以下、Ｎ：０．１０～０．２５％、Ｔｉ：０．０５％以下を含有し、残部がＦｅおよび不可避的不純物からなり、Ｍｄ３０値が８０以下、Ｎｉ－ｂａｌ．が－８以上－４以下であり、かつＮ含有量の上限がＮｉ－ｂａｌ．との関係式で表され、オーステナイト相面積率が４０～７０％であり、２×Ｎｉ＋Ｃｕが３．５以上であることを特徴とする溶接熱影響部の耐食性と靭性が良好な省合金二相ステンレス鋼を開示した。
On the other hand, the inventors of the present invention disclosed in Patent Document 2 that C: 0.06% or less, Si: 0.1 to 1.5%, Mn: 2.0 to 4.0%, P: 0.05% or less S: 0.005% or less, Cr: 19.0 to 23.0%, Ni: 1.00 to 4.0%, Mo: 1.0% or less, Cu: 0.1 to 3.0%, V: 0.05 to 0.5%, Al: 0.003 to 0.050%, O: 0.007% or less, N: 0.10 to 0.25%, Ti: 0.05% or less The balance is Fe and inevitable impurities, the Md 30 value is 80 or less, Ni-bal. Is -8 or more and -4 or less, and the upper limit of the N content is Ni-bal. The austenite phase area ratio is 40 to 70% and 2 × Ni + Cu is 3.5 or more. Alloy-saving two-phase with good corrosion resistance and toughness of weld heat affected zone Stainless steel has been disclosed.
特許文献２に記載の二相ステンレス鋼は、省合金タイプの二相ステンレス鋼において課題となる、溶接熱影響部にクロム窒化物が析出することにより生じる耐食性低下を抑制しうる鋼である。特許文献２のポイントは固溶レベルの微量のＶ添加に加え、オーステナイト量推定式であるＮｉ－ｂａｌ．に応じたＮの上限を規定することである。
The duplex stainless steel described in Patent Document 2 is a steel that can suppress a decrease in corrosion resistance caused by precipitation of chromium nitride in a weld heat affected zone, which is a problem in an alloy-saving duplex stainless steel. The point of Patent Document 2 is that Ni-bal. Is to define an upper limit of N according to.
一方、クラッド鋼板は、合わせ材として用いられるステンレス鋼に耐食性を持たせるとともに、母材に強度・靱性と溶接性を持たせることにより、複合的な特性を経済的に得ることができる熱延鋼材である。輸送船のタンクの１つであるケミカルタンカーは、種々の化学製品を積載して運搬するために、タンクをステンレス製としているものが多くある。
タンクの外側は炭素鋼製の外殻であり、それとの溶接性の関係からタンクにはステンレスクラッド鋼板が使用されることが多い。 On the other hand, a clad steel sheet is a hot-rolled steel material that can provide composite properties economically by providing corrosion resistance to stainless steel used as a laminated material and providing the base material with strength, toughness and weldability. It is. Many chemical tankers, which are one type of tanks for transport ships, have stainless steel tanks for loading and transporting various chemical products.
The outside of the tank is a carbon steel outer shell, and a stainless clad steel plate is often used for the tank because of its weldability.
タンクの外側は炭素鋼製の外殻であり、それとの溶接性の関係からタンクにはステンレスクラッド鋼板が使用されることが多い。 On the other hand, a clad steel sheet is a hot-rolled steel material that can provide composite properties economically by providing corrosion resistance to stainless steel used as a laminated material and providing the base material with strength, toughness and weldability. It is. Many chemical tankers, which are one type of tanks for transport ships, have stainless steel tanks for loading and transporting various chemical products.
The outside of the tank is a carbon steel outer shell, and a stainless clad steel plate is often used for the tank because of its weldability.
従来、合わせ材としてはオーステナイト系ステンレス鋼が多く用いられてきた。しかし、オーステナイト系ステンレス鋼が安価な二相ステンレス鋼に変更される趨勢が進みつつある現状に伴い、クラッド鋼板の合わせ材についても二相ステンレス鋼への置き換えの要求が高まっている。
Conventionally, austenitic stainless steel has often been used as a laminated material. However, with the current trend of changing austenitic stainless steel to cheap duplex stainless steel, there is an increasing demand for replacement of clad steel sheets with duplex stainless steel.
二相ステンレス鋼はＣｒ，Ｍｏ，Ｎｉ，Ｎを多量に含有し、金属間化合物、窒化物が析出しやすいことから、通常の熱間圧延鋼材の製造方法では１０００℃以上の溶体化熱処理によって析出物を固溶させる工程が必須である。しかしながら、クラッド鋼板の製造工程において溶体化熱処理を施すと、母材炭素鋼の靱性が低下してしまうため、上記クラッド鋼板の用途から言えば好ましくない。また、クラッド鋼板を用いる元来の狙いがコスト低減であることに加え、近年の使用エネルギー削減の要求からも、クラッド鋼板の製造工程において溶体化熱処理を省略することが望まれている。
Duplex stainless steel contains a large amount of Cr, Mo, Ni, and N, and intermetallic compounds and nitrides are likely to precipitate. Therefore, in a normal hot-rolled steel manufacturing method, precipitation occurs by solution heat treatment at 1000 ° C or higher. A step of dissolving the product is essential. However, if solution heat treatment is performed in the manufacturing process of the clad steel plate, the toughness of the base carbon steel is lowered, so that it is not preferable in terms of the use of the clad steel plate. Further, in addition to cost reduction as the original aim of using a clad steel plate, it is desired that solution heat treatment be omitted in the production process of the clad steel plate because of the recent demand for reduction of energy used.
このため、クラッド鋼板に関しては、熱処理付加前提で１０００℃以上の高い温度の熱処理によって機械特性を確保することができるように化学組成を工夫した炭素鋼を母材とする（特許文献３など）、熱間圧延条件を制御することにより熱処理を省略して二相ステンレスクラッド鋼板を製造する（特許文献４など）、あるいは熱間圧延中に再加熱して合わせ材中への炭化物等の析出を抑える（特許文献５など）等の措置が行われていた。
このように、従来知見は母材組成やクラッド鋼板製造条件による熱処理省略がほとんどであり、合わせ材である二相ステンレス鋼の改善による解決策は見出されていなかった。 For this reason, with respect to the clad steel plate, a carbon steel whose chemical composition is devised so that mechanical properties can be ensured by heat treatment at a high temperature of 1000 ° C. or higher on the premise of addition of heat treatment is used as a base material (eg, Patent Document 3). By controlling the hot rolling conditions, heat treatment is omitted to manufacture a duplex stainless steel clad steel sheet (Patent Document 4, etc.), or reheating during hot rolling to suppress precipitation of carbides and the like in the laminated material. (Patent Document 5, etc.) and the like have been taken.
As described above, most of the conventional knowledge omits the heat treatment depending on the base material composition and the clad steel plate manufacturing conditions, and no solution has been found by improving the duplex stainless steel as a laminated material.
このように、従来知見は母材組成やクラッド鋼板製造条件による熱処理省略がほとんどであり、合わせ材である二相ステンレス鋼の改善による解決策は見出されていなかった。 For this reason, with respect to the clad steel plate, a carbon steel whose chemical composition is devised so that mechanical properties can be ensured by heat treatment at a high temperature of 1000 ° C. or higher on the premise of addition of heat treatment is used as a base material (eg, Patent Document 3). By controlling the hot rolling conditions, heat treatment is omitted to manufacture a duplex stainless steel clad steel sheet (Patent Document 4, etc.), or reheating during hot rolling to suppress precipitation of carbides and the like in the laminated material. (Patent Document 5, etc.) and the like have been taken.
As described above, most of the conventional knowledge omits the heat treatment depending on the base material composition and the clad steel plate manufacturing conditions, and no solution has been found by improving the duplex stainless steel as a laminated material.
それに対し本発明者らは特許文献６において、二相ステンレス鋼合わせ材が、質量％で、Ｃ：０．０３％以下、Ｓｉ：０．０５～１．０％、Ｍｎ：０．５～７．０％、Ｐ：０．０５％以下、Ｓ：０．０１０％以下、Ｎｉ：０．１～５．０％、Ｃｒ：１８．０～２５．０％、Ｎ：０．０５～０．３０％、Ａｌ：０．００１～０．０５％を含有し、熱間圧延中におけるクロム窒化物の析出に関する指標となるクロム窒化物析出温度ＴＮが８００～９７０℃であることを特徴とする二相ステンレス鋼を合わせ材とするクラッド鋼板を開示した。また本発明者らは特許文献において、母材の靭性と合金元素節減型二相ステンレス鋼合わせ材の耐食性を併せ持ち、溶体化熱処理を省略して使用エネルギーが少なく、環境面でも優れた安価なクラッド鋼板の製造方法を提供した。
On the other hand, the inventors of the present invention disclosed in Patent Document 6 that the duplex stainless steel laminated material is, by mass%, C: 0.03% or less, Si: 0.05 to 1.0%, Mn: 0.5 to 7 0.0%, S: 0.010% or less, Ni: 0.1-5.0%, Cr: 18.0-25.0%, N: 0.05-0. 30%, Al: 0.001 to 0.05%, and having a chromium nitride precipitation temperature TN of 800 to 970 ° C. serving as an index for chromium nitride precipitation during hot rolling. Disclosed is a clad steel plate made of phase stainless steel. In addition, in the patent literature, the inventors of the present invention have both the toughness of the base material and the corrosion resistance of the alloy element-saving duplex stainless steel combined material. A method for manufacturing a steel sheet was provided.
ところで、ケミカルタンカーのうち比較的マイルドな腐食環境の製品向けに使用されているＳＵＳ３０４製タンクの代替として省合金タイプである二相ステンレス鋼（以下、単に省合金二相ステンレス鋼ともいう。）を適用する場合に問題となるのが、線状加熱による耐食性の低下である。
線状加熱は、タンク用鋼材を加工する際、バーナーを掃引し線状に加熱する事によって曲げ加工を行う手法であり、場所によっては最大で１０００℃程度まで加熱される。Ｓ３２１０１等にこの線状加熱を適用すると、窒化物の析出が生じることにより加熱部の耐食性が低下する。本発明者らは特許文献７で、この線状加熱性が良好な二相ステンレス鋼を開示している。 By the way, a duplex stainless steel that is an alloy-saving type (hereinafter also simply referred to as an alloy-saving duplex stainless steel) is used as an alternative to a tank made of SUS304 that is used for a product of a relatively mild corrosive environment among chemical tankers. A problem in application is a reduction in corrosion resistance due to linear heating.
The linear heating is a technique for performing bending by sweeping a burner and heating in a linear manner when processing a steel material for tanks, and is heated up to about 1000 ° C. depending on the place. When this linear heating is applied to S32101 or the like, the precipitation of nitrides occurs, so that the corrosion resistance of the heating part decreases. In the patent document 7, the present inventors have disclosed a duplex stainless steel having a good linear heating property.
線状加熱は、タンク用鋼材を加工する際、バーナーを掃引し線状に加熱する事によって曲げ加工を行う手法であり、場所によっては最大で１０００℃程度まで加熱される。Ｓ３２１０１等にこの線状加熱を適用すると、窒化物の析出が生じることにより加熱部の耐食性が低下する。本発明者らは特許文献７で、この線状加熱性が良好な二相ステンレス鋼を開示している。 By the way, a duplex stainless steel that is an alloy-saving type (hereinafter also simply referred to as an alloy-saving duplex stainless steel) is used as an alternative to a tank made of SUS304 that is used for a product of a relatively mild corrosive environment among chemical tankers. A problem in application is a reduction in corrosion resistance due to linear heating.
The linear heating is a technique for performing bending by sweeping a burner and heating in a linear manner when processing a steel material for tanks, and is heated up to about 1000 ° C. depending on the place. When this linear heating is applied to S32101 or the like, the precipitation of nitrides occurs, so that the corrosion resistance of the heating part decreases. In the patent document 7, the present inventors have disclosed a duplex stainless steel having a good linear heating property.
ケミカルタンカーに二相ステンレス鋼クラッド鋼板を適用するためには、上述したようなクラッド鋼板製造時の溶体化熱処理の省略や、線状加熱性を向上させることが求められる。これらを達成するためには、特許文献７で開示された線状加熱性に優れた二相ステンレス鋼を、特許文献６で開示されたクラッド鋼とすれば良いと考えられた。しかしながら、本発明者らが、試行したところ、単に特許文献７の二相ステンレス鋼をクラッド鋼板に適用しただけでは、十分な線状加熱性を備えることが出来ない場合があることを知見した。なぜなら、後述のように、溶体化熱処理を省略したクラッド鋼板を線状加熱すると、耐食性低下温度域を二度通過することとなり、より耐食性低下が起こりやすくなるためである。即ち、合わせ材として二相ステンレス鋼を用いた線状加熱性に優れたクラッド鋼板を製造するには、従来の知見だけでは足りないことが分かった。
本発明は、上記事実に鑑みてなされたものであって、その目的は、合金コストを極力抑えた上で、溶体化熱処理の省略を可能とするとともに、線状加熱時の耐食性低下を抑制しうる安価な二相ステンレス鋼を合わせ材とするクラッド鋼板およびその製造方法を提供することである。 In order to apply the duplex stainless steel clad steel plate to the chemical tanker, it is required to omit the solution heat treatment during the production of the clad steel plate as described above and to improve the linear heatability. In order to achieve these, it was thought that the duplex stainless steel disclosed in Patent Document 7 and excellent in linear heatability may be the clad steel disclosed in Patent Document 6. However, when the present inventors tried, it was found that there was a case where sufficient duplex heating could not be provided by simply applying the duplex stainless steel of Patent Document 7 to the clad steel plate. This is because, as will be described later, when the clad steel sheet without the solution heat treatment is linearly heated, it passes through the corrosion resistance lowering temperature range twice, and the corrosion resistance lowers more easily. That is, it has been found that conventional knowledge alone is not sufficient to produce a clad steel plate excellent in linear heatability using a duplex stainless steel as a laminated material.
The present invention has been made in view of the above-mentioned facts, and its purpose is to suppress the alloy cost as much as possible and to omit the solution heat treatment and to suppress the corrosion resistance decrease during the linear heating. It is an object to provide a clad steel plate using a cheap inexpensive duplex stainless steel as a laminated material and a method for producing the same.
本発明は、上記事実に鑑みてなされたものであって、その目的は、合金コストを極力抑えた上で、溶体化熱処理の省略を可能とするとともに、線状加熱時の耐食性低下を抑制しうる安価な二相ステンレス鋼を合わせ材とするクラッド鋼板およびその製造方法を提供することである。 In order to apply the duplex stainless steel clad steel plate to the chemical tanker, it is required to omit the solution heat treatment during the production of the clad steel plate as described above and to improve the linear heatability. In order to achieve these, it was thought that the duplex stainless steel disclosed in Patent Document 7 and excellent in linear heatability may be the clad steel disclosed in Patent Document 6. However, when the present inventors tried, it was found that there was a case where sufficient duplex heating could not be provided by simply applying the duplex stainless steel of Patent Document 7 to the clad steel plate. This is because, as will be described later, when the clad steel sheet without the solution heat treatment is linearly heated, it passes through the corrosion resistance lowering temperature range twice, and the corrosion resistance lowers more easily. That is, it has been found that conventional knowledge alone is not sufficient to produce a clad steel plate excellent in linear heatability using a duplex stainless steel as a laminated material.
The present invention has been made in view of the above-mentioned facts, and its purpose is to suppress the alloy cost as much as possible and to omit the solution heat treatment and to suppress the corrosion resistance decrease during the linear heating. It is an object to provide a clad steel plate using a cheap inexpensive duplex stainless steel as a laminated material and a method for producing the same.
線状加熱において、Ｍｏを多く含有する従来型の二相ステンレス鋼の場合は、シグマ相のような金属間化合物の生成を生じる。これに対して、本発明のような省合金二相ステンレス鋼の場合はＭｏの含有量を抑制させたものであるため、金属間化合物の生成はほぼ無いが、一方で、クロム窒化物の析出が生じる。このクロム窒化物は九百数十℃以下で析出し、析出速度は７００℃付近が最も速い。そしてこれらの温度域は熱間圧延後の冷却時および線状加熱の温度域に合致する。このため、通常、熱間圧延を終了した状態のクラッド材では、耐食性を低下させるクロム窒化物が合わせ材中に析出し、線状加熱によりクロム窒化物の析出が更に助長される形となる。
In linear heating, in the case of a conventional duplex stainless steel containing a large amount of Mo, an intermetallic compound such as a sigma phase is generated. On the other hand, in the case of the alloy-saving duplex stainless steel as in the present invention, since the content of Mo is suppressed, there is almost no formation of intermetallic compounds, but on the other hand, precipitation of chromium nitride Occurs. The chromium nitride precipitates at a temperature of not less than tens of tens of degrees Celsius, and the deposition rate is fastest around 700 ° C. And these temperature ranges correspond with the temperature range of the time of cooling after a hot rolling, and linear heating. For this reason, normally, in the clad material after hot rolling is finished, chromium nitride that lowers corrosion resistance is precipitated in the laminated material, and the precipitation of chromium nitride is further promoted by linear heating.
本発明者らは、クラッド鋼板の合わせ材として、省合金二相ステンレス鋼の中で窒化物が析出し難い成分系のものを使用することで、解決策を見出すことを考えた。特許文献２や特許文献７にて示された鋼材は溶接熱影響部の特性低下を抑制するために窒化物析出を抑制している鋼材である。そこで、このような鋼材およびその周辺成分の鋼材を適用し、以下の実験をおこなった。
The present inventors considered finding a solution by using, as a laminated material of clad steel plates, a component system in which a nitride is difficult to precipitate in an alloy-saving duplex stainless steel. The steel materials shown in Patent Document 2 and Patent Document 7 are steel materials that suppress nitride precipitation in order to suppress deterioration in characteristics of the weld heat affected zone. Therefore, the following experiment was conducted by applying such steel materials and steel materials of peripheral components.
上記鋼材を合わせ材として炭素鋼と合わせた素材を用い、熱間圧延の加熱温度を１１５０～１２５０℃、熱間圧延の最終仕上圧延パスの入側温度およびその後の冷却速度をそれぞれ変更し、鋼材厚さを１０ｍｍから３５ｍｍの範囲とし、そのうち合わせ材の厚さを３ｍｍとした熱間圧延クラッド鋼材を得た。
更に本発明者らは、当該熱間圧延クラッド鋼材に関して線状加熱に対応する熱処理を行った後、耐食性評価と析出物の分析を行った。その結果、析出物分析で耐食性良好な鋼材を判別できることが分かった。更に、線状加熱実施後において耐食性が良好なクラッド鋼材を得るためには、特定の成分系の鋼材を用い、適正な熱延及び冷却の履歴を確保することが有効であることを本発明者らは見出した。 Using a steel material combined with carbon steel as a combination material, the heating temperature of the hot rolling is 1150 to 1250 ° C., the entry temperature of the final finishing rolling pass of the hot rolling and the subsequent cooling rate are changed, respectively. A hot-rolled clad steel material having a thickness in the range of 10 mm to 35 mm, of which the thickness of the laminated material was 3 mm was obtained.
Furthermore, the present inventors performed a heat treatment corresponding to linear heating on the hot-rolled clad steel material, and then performed corrosion resistance evaluation and analysis of precipitates. As a result, it was found that the steel material having good corrosion resistance can be distinguished by the precipitate analysis. Furthermore, in order to obtain a clad steel material having good corrosion resistance after the linear heating, it is effective to use a steel material of a specific component system and ensure an appropriate hot rolling and cooling history. Found.
更に本発明者らは、当該熱間圧延クラッド鋼材に関して線状加熱に対応する熱処理を行った後、耐食性評価と析出物の分析を行った。その結果、析出物分析で耐食性良好な鋼材を判別できることが分かった。更に、線状加熱実施後において耐食性が良好なクラッド鋼材を得るためには、特定の成分系の鋼材を用い、適正な熱延及び冷却の履歴を確保することが有効であることを本発明者らは見出した。 Using a steel material combined with carbon steel as a combination material, the heating temperature of the hot rolling is 1150 to 1250 ° C., the entry temperature of the final finishing rolling pass of the hot rolling and the subsequent cooling rate are changed, respectively. A hot-rolled clad steel material having a thickness in the range of 10 mm to 35 mm, of which the thickness of the laminated material was 3 mm was obtained.
Furthermore, the present inventors performed a heat treatment corresponding to linear heating on the hot-rolled clad steel material, and then performed corrosion resistance evaluation and analysis of precipitates. As a result, it was found that the steel material having good corrosion resistance can be distinguished by the precipitate analysis. Furthermore, in order to obtain a clad steel material having good corrosion resistance after the linear heating, it is effective to use a steel material of a specific component system and ensure an appropriate hot rolling and cooling history. Found.
まず、このクロム窒化物は７００℃付近で最も析出速度が速いため、この温度での熱処理材を評価することとした。供試材の耐食性と鋼材の組織を種々の方法で観察した結果、当該鋼材においてフェライト相粒界へのＣｒ窒化物析出による鋭敏化が耐食性低下をもたらすので、このＣｒ窒化物の析出量を抽出残渣分析にて測定することにより、耐食性劣化が抑制された鋼材を判別できることを見出した。そして、本発明者らは、熱間圧延クラッド鋼材において、析出物中のクロム量を０．０５％以下に抑制することにより、線状加熱処理後の耐食性（以下、単に線状加熱性ともいう）を良好に確保できることを見出した。
また、このように窒化物の析出を抑制する手法について、各鋼材について熱延温度およびその後の冷却条件を種々変更し鋭意検討した結果、特許文献２や特許文献７の鋼よりも熱延および冷却時の窒化物の析出を抑制した特定の鋼においてのみ、前述の７００℃熱処理条件で窒化物の析出抑制が可能であることが見出された。更に当該鋼材において熱延の温度およびその後の冷却条件を規定することにより、線状加熱を行った後も窒化物の析出量を抑制し耐食性が確保できることが見出された。
さらにその上で、ＳＵＳ３０４と同等もしくはそれ以上の耐食性を確保するためには析出鋭敏化による耐食性低下をも補償した成分系にすべきであることを発明者らは見出した。以上の実験を通じて、省合金二相ステンレス鋼を合わせ材として用いて溶体化熱処理を省略したクラッド鋼板について、線状加熱性が良好な条件を明示した本発明の完成に至った。 First, since this chromium nitride has the fastest precipitation rate around 700 ° C., the heat treatment material at this temperature was evaluated. As a result of observing the corrosion resistance of the test material and the structure of the steel by various methods, the sensitization by Cr nitride precipitation at the ferrite phase grain boundary in the steel material brings about a decrease in corrosion resistance. It has been found that the steel material in which the corrosion resistance deterioration is suppressed can be determined by measuring by residue analysis. And in the hot-rolled clad steel material, the present inventors suppress the chromium content in the precipitates to 0.05% or less, whereby the corrosion resistance after the linear heat treatment (hereinafter also simply referred to as linear heatability). ) Was successfully secured.
Moreover, about the method which suppresses precipitation of nitride in this way, as a result of changing variously the hot rolling temperature and subsequent cooling conditions about each steel material, and earnestly examining it, hot rolling and cooling were compared with the steel of patent document 2 and patent document 7. It has been found that only in a specific steel that suppresses precipitation of nitride at the time, the precipitation of nitride can be suppressed under the above-mentioned 700 ° C. heat treatment conditions. Furthermore, it has been found that by defining the hot rolling temperature and the subsequent cooling conditions in the steel material, the amount of nitride precipitation can be suppressed and corrosion resistance can be ensured even after linear heating.
Furthermore, the inventors have found that in order to ensure the corrosion resistance equivalent to or higher than that of SUS304, the component system should be compensated for the decrease in corrosion resistance due to precipitation sensitization. Through the above experiments, the present invention has been completed, in which the condition of good linear heatability is clearly specified for a clad steel plate that uses alloy-saving duplex stainless steel as a laminated material and omits solution heat treatment.
また、このように窒化物の析出を抑制する手法について、各鋼材について熱延温度およびその後の冷却条件を種々変更し鋭意検討した結果、特許文献２や特許文献７の鋼よりも熱延および冷却時の窒化物の析出を抑制した特定の鋼においてのみ、前述の７００℃熱処理条件で窒化物の析出抑制が可能であることが見出された。更に当該鋼材において熱延の温度およびその後の冷却条件を規定することにより、線状加熱を行った後も窒化物の析出量を抑制し耐食性が確保できることが見出された。
さらにその上で、ＳＵＳ３０４と同等もしくはそれ以上の耐食性を確保するためには析出鋭敏化による耐食性低下をも補償した成分系にすべきであることを発明者らは見出した。以上の実験を通じて、省合金二相ステンレス鋼を合わせ材として用いて溶体化熱処理を省略したクラッド鋼板について、線状加熱性が良好な条件を明示した本発明の完成に至った。 First, since this chromium nitride has the fastest precipitation rate around 700 ° C., the heat treatment material at this temperature was evaluated. As a result of observing the corrosion resistance of the test material and the structure of the steel by various methods, the sensitization by Cr nitride precipitation at the ferrite phase grain boundary in the steel material brings about a decrease in corrosion resistance. It has been found that the steel material in which the corrosion resistance deterioration is suppressed can be determined by measuring by residue analysis. And in the hot-rolled clad steel material, the present inventors suppress the chromium content in the precipitates to 0.05% or less, whereby the corrosion resistance after the linear heat treatment (hereinafter also simply referred to as linear heatability). ) Was successfully secured.
Moreover, about the method which suppresses precipitation of nitride in this way, as a result of changing variously the hot rolling temperature and subsequent cooling conditions about each steel material, and earnestly examining it, hot rolling and cooling were compared with the steel of patent document 2 and patent document 7. It has been found that only in a specific steel that suppresses precipitation of nitride at the time, the precipitation of nitride can be suppressed under the above-mentioned 700 ° C. heat treatment conditions. Furthermore, it has been found that by defining the hot rolling temperature and the subsequent cooling conditions in the steel material, the amount of nitride precipitation can be suppressed and corrosion resistance can be ensured even after linear heating.
Furthermore, the inventors have found that in order to ensure the corrosion resistance equivalent to or higher than that of SUS304, the component system should be compensated for the decrease in corrosion resistance due to precipitation sensitization. Through the above experiments, the present invention has been completed, in which the condition of good linear heatability is clearly specified for a clad steel plate that uses alloy-saving duplex stainless steel as a laminated material and omits solution heat treatment.
以上の知見より、本発明の要旨とするところは以下の通りである。
［１］ 二相ステンレス鋼を合わせ材、炭素鋼もしくは合金鋼を母材とするクラッド鋼板であって、該二相ステンレス鋼が、質量％にて、Ｃ：０．０３％以下、Ｓｉ：０．１～１．０％、Ｍｎ：１．０～７．０％、Ｐ：０．０５％以下、Ｓ：０．００５％以下、Ｃｒ：２０．５～２４．０％、Ｎｉ：１．５～５．０％、Ｖ：０．０５～０．５％、Ａｌ：０．００３～０．０５０％、Ｏ：０．００７％以下、Ｎ：０．１０～０．２５％を含有し、さらに、Ｍｏ：１．０％以下及び／またはＣｕ：２．０％以下を含有し、残部がＦｅおよび不可避的不純物からなり、オーステナイト相面積率が４０～７０％であり、下記（１）式で示されるＣｒ窒化物の析出開始温度計算値Ｎpreが９２０℃以下であり、７００℃で３分間等温熱処理した後、前記クラッド鋼板から前記合わせ材のみを切り出し電解抽出残渣分析を行って求めた析出物中のクロム量が０．０５％以下であることを特徴とする、線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板。
Ｎｐｒｅ＝１２Ｃｒ＋５０Ｓｉ＋３６Ｍｏ－２０Ｎｉ－１５Ｍｎ＋２８Ｃｕ
＋４７０Ｎ－２９０Ｃ＋６２０・・・・・・（１）
上記の式において各元素名は何れもその含有量（質量％）を表す。また、上記の式において鋼中に含有されない元素については、０を代入することとする。
［２］ 上記［１］に記載の二相ステンレス鋼において、Ｎｂを０．０２～０．１５％かつＮｂ×Ｎが０．００３～０．０１５（ここで、Ｎｂ、Ｎは夫々の含有量の質量％を表す）となるように含有することを特徴とする線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板。
［３］ 上記［１］または［２］に記載の二相ステンレス鋼において、Ｃａ：０．００５０％以下、Ｍｇ：０．００５０％以下、ＲＥＭ：０．０５０％以下、Ｂ：０．００４０％以下の１種または２種以上を含有することを特徴とする線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板。
［４］ 上記［１］ないし［３］のいずれか一項に記載の二相ステンレス鋼において、Ｃｏを０．０２～１．００％含有することを特徴とする線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板。
［５］ 上記［１］ないし［４］のいずれか一項に記載の二相ステンレス鋼において、更に質量％にて
Ｔｉ：０．０５％以下、
Ｗ：１．０％以下、
Ｓｎ：０．１％以下の１種または２種以上を含有することを特徴とする線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板。
［６］ 上記［１］～［５］のいずれかに記載の二相ステンレス鋼を合わせ材とし、前記合わせ材と、普通鋼もしくは合金鋼からなる母材とを組み合わせた被圧延素材を、９００℃以上で熱間圧延し、その後の冷却時において９００～６００℃までの通過時間を６０秒以上１５分以内とし、前記冷却後はそのまま熱処理せずにクラッド鋼板とすることを特徴とする線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板の製造方法。 From the above findings, the gist of the present invention is as follows.
[1] A clad steel plate using a duplex stainless steel as a base material, a carbon steel or an alloy steel as a base material, wherein the duplex stainless steel is C: 0.03% or less in terms of mass%, Si: 0 0.1 to 1.0%, Mn: 1.0 to 7.0%, P: 0.05% or less, S: 0.005% or less, Cr: 20.5 to 24.0%, Ni: 1. 5 to 5.0%, V: 0.05 to 0.5%, Al: 0.003 to 0.050%, O: 0.007% or less, N: 0.10 to 0.25% Further, it contains Mo: 1.0% or less and / or Cu: 2.0% or less, the balance is made of Fe and inevitable impurities, the austenite phase area ratio is 40 to 70%, and the following (1) The calculated Cr nitride precipitation start temperature Npre shown by the formula is 920 ° C. or lower, and after isothermal heat treatment at 700 ° C. for 3 minutes, A duplex stainless steel with good linear heatability, characterized in that the amount of chromium in the precipitate obtained by cutting out only the laminated material from the steel plate and conducting an electrolytic extraction residue analysis is 0.05% or less. Clad steel sheet used as a laminated material.
Npre = 12Cr + 50Si + 36Mo-20Ni-15Mn + 28Cu
+ 470N-290C + 620 (1)
In the above formula, each element name represents its content (% by mass). In the above formula, 0 is substituted for elements not contained in the steel.
[2] In the duplex stainless steel according to the above [1], Nb is 0.02 to 0.15% and Nb × N is 0.003 to 0.015 (where Nb and N are the respective contents) A clad steel sheet comprising a duplex stainless steel with good linear heatability, characterized in that it is contained so as to be a mass% of
[3] In the duplex stainless steel according to the above [1] or [2], Ca: 0.0050% or less, Mg: 0.0050% or less, REM: 0.050% or less, B: 0.0040% A clad steel sheet comprising a duplex stainless steel with good linear heatability, characterized by containing one or more of the following:
[4] The duplex stainless steel according to any one of [1] to [3] above, characterized in that it contains 0.02 to 1.00% of Co and has a good linear heating property A clad steel plate made of stainless steel.
[5] In the duplex stainless steel according to any one of the above [1] to [4], Ti: 0.05% or less in mass%.
W: 1.0% or less,
Sn: A clad steel plate comprising a duplex stainless steel with good linear heatability, characterized by containing one or more of 0.1% or less.
[6] A rolled material obtained by combining the duplex stainless steel according to any one of the above [1] to [5] with a combination material and a base material made of ordinary steel or alloy steel, 900 A linear shape characterized in that it is hot-rolled at a temperature of not lower than ℃ and the passing time from 900 to 600 ℃ is set to 60 seconds or longer and within 15 minutes at the time of subsequent cooling. A method for producing a clad steel plate made of a duplex stainless steel with good heatability.
［１］ 二相ステンレス鋼を合わせ材、炭素鋼もしくは合金鋼を母材とするクラッド鋼板であって、該二相ステンレス鋼が、質量％にて、Ｃ：０．０３％以下、Ｓｉ：０．１～１．０％、Ｍｎ：１．０～７．０％、Ｐ：０．０５％以下、Ｓ：０．００５％以下、Ｃｒ：２０．５～２４．０％、Ｎｉ：１．５～５．０％、Ｖ：０．０５～０．５％、Ａｌ：０．００３～０．０５０％、Ｏ：０．００７％以下、Ｎ：０．１０～０．２５％を含有し、さらに、Ｍｏ：１．０％以下及び／またはＣｕ：２．０％以下を含有し、残部がＦｅおよび不可避的不純物からなり、オーステナイト相面積率が４０～７０％であり、下記（１）式で示されるＣｒ窒化物の析出開始温度計算値Ｎpreが９２０℃以下であり、７００℃で３分間等温熱処理した後、前記クラッド鋼板から前記合わせ材のみを切り出し電解抽出残渣分析を行って求めた析出物中のクロム量が０．０５％以下であることを特徴とする、線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板。
Ｎｐｒｅ＝１２Ｃｒ＋５０Ｓｉ＋３６Ｍｏ－２０Ｎｉ－１５Ｍｎ＋２８Ｃｕ
＋４７０Ｎ－２９０Ｃ＋６２０・・・・・・（１）
上記の式において各元素名は何れもその含有量（質量％）を表す。また、上記の式において鋼中に含有されない元素については、０を代入することとする。
［２］ 上記［１］に記載の二相ステンレス鋼において、Ｎｂを０．０２～０．１５％かつＮｂ×Ｎが０．００３～０．０１５（ここで、Ｎｂ、Ｎは夫々の含有量の質量％を表す）となるように含有することを特徴とする線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板。
［３］ 上記［１］または［２］に記載の二相ステンレス鋼において、Ｃａ：０．００５０％以下、Ｍｇ：０．００５０％以下、ＲＥＭ：０．０５０％以下、Ｂ：０．００４０％以下の１種または２種以上を含有することを特徴とする線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板。
［４］ 上記［１］ないし［３］のいずれか一項に記載の二相ステンレス鋼において、Ｃｏを０．０２～１．００％含有することを特徴とする線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板。
［５］ 上記［１］ないし［４］のいずれか一項に記載の二相ステンレス鋼において、更に質量％にて
Ｔｉ：０．０５％以下、
Ｗ：１．０％以下、
Ｓｎ：０．１％以下の１種または２種以上を含有することを特徴とする線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板。
［６］ 上記［１］～［５］のいずれかに記載の二相ステンレス鋼を合わせ材とし、前記合わせ材と、普通鋼もしくは合金鋼からなる母材とを組み合わせた被圧延素材を、９００℃以上で熱間圧延し、その後の冷却時において９００～６００℃までの通過時間を６０秒以上１５分以内とし、前記冷却後はそのまま熱処理せずにクラッド鋼板とすることを特徴とする線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板の製造方法。 From the above findings, the gist of the present invention is as follows.
[1] A clad steel plate using a duplex stainless steel as a base material, a carbon steel or an alloy steel as a base material, wherein the duplex stainless steel is C: 0.03% or less in terms of mass%, Si: 0 0.1 to 1.0%, Mn: 1.0 to 7.0%, P: 0.05% or less, S: 0.005% or less, Cr: 20.5 to 24.0%, Ni: 1. 5 to 5.0%, V: 0.05 to 0.5%, Al: 0.003 to 0.050%, O: 0.007% or less, N: 0.10 to 0.25% Further, it contains Mo: 1.0% or less and / or Cu: 2.0% or less, the balance is made of Fe and inevitable impurities, the austenite phase area ratio is 40 to 70%, and the following (1) The calculated Cr nitride precipitation start temperature Npre shown by the formula is 920 ° C. or lower, and after isothermal heat treatment at 700 ° C. for 3 minutes, A duplex stainless steel with good linear heatability, characterized in that the amount of chromium in the precipitate obtained by cutting out only the laminated material from the steel plate and conducting an electrolytic extraction residue analysis is 0.05% or less. Clad steel sheet used as a laminated material.
Npre = 12Cr + 50Si + 36Mo-20Ni-15Mn + 28Cu
+ 470N-290C + 620 (1)
In the above formula, each element name represents its content (% by mass). In the above formula, 0 is substituted for elements not contained in the steel.
[2] In the duplex stainless steel according to the above [1], Nb is 0.02 to 0.15% and Nb × N is 0.003 to 0.015 (where Nb and N are the respective contents) A clad steel sheet comprising a duplex stainless steel with good linear heatability, characterized in that it is contained so as to be a mass% of
[3] In the duplex stainless steel according to the above [1] or [2], Ca: 0.0050% or less, Mg: 0.0050% or less, REM: 0.050% or less, B: 0.0040% A clad steel sheet comprising a duplex stainless steel with good linear heatability, characterized by containing one or more of the following:
[4] The duplex stainless steel according to any one of [1] to [3] above, characterized in that it contains 0.02 to 1.00% of Co and has a good linear heating property A clad steel plate made of stainless steel.
[5] In the duplex stainless steel according to any one of the above [1] to [4], Ti: 0.05% or less in mass%.
W: 1.0% or less,
Sn: A clad steel plate comprising a duplex stainless steel with good linear heatability, characterized by containing one or more of 0.1% or less.
[6] A rolled material obtained by combining the duplex stainless steel according to any one of the above [1] to [5] with a combination material and a base material made of ordinary steel or alloy steel, 900 A linear shape characterized in that it is hot-rolled at a temperature of not lower than ℃ and the passing time from 900 to 600 ℃ is set to 60 seconds or longer and within 15 minutes at the time of subsequent cooling. A method for producing a clad steel plate made of a duplex stainless steel with good heatability.
本発明によれば、省合金タイプ二相ステンレス鋼を合わせ材とし、炭素鋼もしくは合金鋼を母材とするクラッド鋼板において、輸送用のタンク等に適用される際の大きな課題の一つである線状加熱時の耐食性低下を抑制することが可能となる。その結果、例えばケミカルタンカーへの適用が実現し、従来鋼より合金元素を節減した二相ステンレス鋼を合わせ材とするクラッド鋼板を、安価で少ないエネルギーで製造できる。このため、本発明のクラッド鋼板およびその製造方法が産業面、環境面に寄与するところは極めて大である。
According to the present invention, in a clad steel plate using alloy-saving type duplex stainless steel as a combination material and carbon steel or alloy steel as a base material, it is one of the major problems when applied to a tank for transportation and the like. It becomes possible to suppress a decrease in corrosion resistance during linear heating. As a result, application to, for example, a chemical tanker can be realized, and a clad steel plate made of a duplex stainless steel in which alloy elements are reduced compared to conventional steel can be manufactured at low cost with less energy. For this reason, the place which the clad steel plate of this invention and its manufacturing method contribute to an industrial surface and an environmental surface is very large.
（二相ステンレス鋼を合わせ材とするクラッド鋼板）
以下に本実施形態に係るクラッド鋼板を詳細に説明する。なお、成分についての％は、特に断りがない場合は質量％を意味する。
先ず、本実施形態の二相ステンレス鋼を合わせ材とするクラッド鋼板について詳細に説明する。
本実施形態に係る二相ステンレス鋼を合わせ材とするクラッド鋼板は、二相ステンレス鋼を合わせ材、炭素鋼もしくは合金鋼を母材とするクラッド鋼板であって、該二相ステンレス鋼が、質量％にて、Ｃ：０．０３％以下、Ｓｉ：０．１～１．０％、Ｍｎ：１．０～７．０％、Ｐ：０．０５％以下、Ｓ：０．００５％以下、Ｃｒ：２０．５～２４．０％、Ｎｉ：１．５～５．０％、Ｖ：０．０５～０．５％、Ａｌ：０．００３～０．０５０％、Ｏ：０．００７％以下、Ｎ：０．１０～０．２５％を含有し、さらに、Ｍｏ：１．０％以下及び／またはＣｕ：２．０％以下を含有し、残部がＦｅおよび不可避的不純物からなり、オーステナイト相面積率が４０～７０％であり、下記（１）式で示されるＣｒ窒化物の析出開始温度計算値Ｎｐｒｅが９２０℃以下であり、７００℃で３分間等温熱処理した後、合わせ材のみを切り出し電解抽出残渣分析を行って求めた析出物中のクロム量が０．０５％以下であることを特徴とする。
Ｎｐｒｅ＝１２Ｃｒ＋５０Ｓｉ＋３６Ｍｏ－２０Ｎｉ－１５Ｍｎ
＋２８Ｃｕ＋４７０Ｎ－２９０Ｃ＋６２０・・・・・・（１）
上記の式において各元素名は何れもその含有量（％）を表す。
また、鋼中に含有されない元素については、０を代入することとする。
以下に、本実施形態に係る二相ステンレス鋼を合わせ材とするクラッド鋼板における合わせ材（二相ステンレス鋼）の成分の限定理由について説明する。 (Clad steel plate made of duplex stainless steel)
The clad steel plate according to the present embodiment will be described in detail below. In addition,% about a component means the mass% unless there is particular notice.
First, the clad steel plate which uses the duplex stainless steel of this embodiment as a laminated material is demonstrated in detail.
The clad steel plate comprising the duplex stainless steel according to the present embodiment is a clad steel plate comprising the duplex stainless steel as a laminate, carbon steel or alloy steel as a base material, and the duplex stainless steel has a mass. %: C: 0.03% or less, Si: 0.1 to 1.0%, Mn: 1.0 to 7.0%, P: 0.05% or less, S: 0.005% or less, Cr: 20.5 to 24.0%, Ni: 1.5 to 5.0%, V: 0.05 to 0.5%, Al: 0.003 to 0.050%, O: 0.007% In the following, N: 0.10 to 0.25%, Mo: 1.0% or less and / or Cu: 2.0% or less, the balance consisting of Fe and inevitable impurities, austenite The phase area ratio is 40 to 70%, and the Cr nitride precipitation start temperature calculation value Npre represented by the following formula (1) is The temperature is 20 ° C. or less, and after the isothermal heat treatment at 700 ° C. for 3 minutes, only the combined material is cut out and the amount of chromium in the precipitate obtained by performing electrolytic extraction residue analysis is 0.05% or less. .
Npre = 12Cr + 50Si + 36Mo-20Ni-15Mn
+ 28Cu + 470N-290C + 620 (1)
In the above formula, each element name represents its content (%).
For elements not contained in steel, 0 is substituted.
Below, the reason for limitation of the component of the laminated material (duplex stainless steel) in the clad steel plate which uses the duplex stainless steel which concerns on this embodiment as a laminated material is demonstrated.
以下に本実施形態に係るクラッド鋼板を詳細に説明する。なお、成分についての％は、特に断りがない場合は質量％を意味する。
先ず、本実施形態の二相ステンレス鋼を合わせ材とするクラッド鋼板について詳細に説明する。
本実施形態に係る二相ステンレス鋼を合わせ材とするクラッド鋼板は、二相ステンレス鋼を合わせ材、炭素鋼もしくは合金鋼を母材とするクラッド鋼板であって、該二相ステンレス鋼が、質量％にて、Ｃ：０．０３％以下、Ｓｉ：０．１～１．０％、Ｍｎ：１．０～７．０％、Ｐ：０．０５％以下、Ｓ：０．００５％以下、Ｃｒ：２０．５～２４．０％、Ｎｉ：１．５～５．０％、Ｖ：０．０５～０．５％、Ａｌ：０．００３～０．０５０％、Ｏ：０．００７％以下、Ｎ：０．１０～０．２５％を含有し、さらに、Ｍｏ：１．０％以下及び／またはＣｕ：２．０％以下を含有し、残部がＦｅおよび不可避的不純物からなり、オーステナイト相面積率が４０～７０％であり、下記（１）式で示されるＣｒ窒化物の析出開始温度計算値Ｎｐｒｅが９２０℃以下であり、７００℃で３分間等温熱処理した後、合わせ材のみを切り出し電解抽出残渣分析を行って求めた析出物中のクロム量が０．０５％以下であることを特徴とする。
Ｎｐｒｅ＝１２Ｃｒ＋５０Ｓｉ＋３６Ｍｏ－２０Ｎｉ－１５Ｍｎ
＋２８Ｃｕ＋４７０Ｎ－２９０Ｃ＋６２０・・・・・・（１）
上記の式において各元素名は何れもその含有量（％）を表す。
また、鋼中に含有されない元素については、０を代入することとする。
以下に、本実施形態に係る二相ステンレス鋼を合わせ材とするクラッド鋼板における合わせ材（二相ステンレス鋼）の成分の限定理由について説明する。 (Clad steel plate made of duplex stainless steel)
The clad steel plate according to the present embodiment will be described in detail below. In addition,% about a component means the mass% unless there is particular notice.
First, the clad steel plate which uses the duplex stainless steel of this embodiment as a laminated material is demonstrated in detail.
The clad steel plate comprising the duplex stainless steel according to the present embodiment is a clad steel plate comprising the duplex stainless steel as a laminate, carbon steel or alloy steel as a base material, and the duplex stainless steel has a mass. %: C: 0.03% or less, Si: 0.1 to 1.0%, Mn: 1.0 to 7.0%, P: 0.05% or less, S: 0.005% or less, Cr: 20.5 to 24.0%, Ni: 1.5 to 5.0%, V: 0.05 to 0.5%, Al: 0.003 to 0.050%, O: 0.007% In the following, N: 0.10 to 0.25%, Mo: 1.0% or less and / or Cu: 2.0% or less, the balance consisting of Fe and inevitable impurities, austenite The phase area ratio is 40 to 70%, and the Cr nitride precipitation start temperature calculation value Npre represented by the following formula (1) is The temperature is 20 ° C. or less, and after the isothermal heat treatment at 700 ° C. for 3 minutes, only the combined material is cut out and the amount of chromium in the precipitate obtained by performing electrolytic extraction residue analysis is 0.05% or less. .
Npre = 12Cr + 50Si + 36Mo-20Ni-15Mn
+ 28Cu + 470N-290C + 620 (1)
In the above formula, each element name represents its content (%).
For elements not contained in steel, 0 is substituted.
Below, the reason for limitation of the component of the laminated material (duplex stainless steel) in the clad steel plate which uses the duplex stainless steel which concerns on this embodiment as a laminated material is demonstrated.
＜Ｃ：０．０３％以下＞
Ｃの含有量は、二相ステンレス鋼の耐食性を確保するために０．０３％以下に制限される。Ｃが０．０３％を越えて含有されると熱間圧延時にＣｒ炭化物が生成するので、耐食性、靱性が劣化する。このような観点から、好ましいＣ含有量は０．０２５％以下であり、より好ましくは０．０２２％以下である。一方、Ｃ含有量を極端に低減することは大幅なコストアップになるため、０．００１％以上であることが好ましく、より好ましくは０．０１０％以上である。 <C: 0.03% or less>
The C content is limited to 0.03% or less in order to ensure the corrosion resistance of the duplex stainless steel. When C exceeds 0.03%, Cr carbide is generated during hot rolling, so that corrosion resistance and toughness deteriorate. From such a viewpoint, the preferable C content is 0.025% or less, and more preferably 0.022% or less. On the other hand, since extremely reducing the C content significantly increases the cost, it is preferably 0.001% or more, and more preferably 0.010% or more.
Ｃの含有量は、二相ステンレス鋼の耐食性を確保するために０．０３％以下に制限される。Ｃが０．０３％を越えて含有されると熱間圧延時にＣｒ炭化物が生成するので、耐食性、靱性が劣化する。このような観点から、好ましいＣ含有量は０．０２５％以下であり、より好ましくは０．０２２％以下である。一方、Ｃ含有量を極端に低減することは大幅なコストアップになるため、０．００１％以上であることが好ましく、より好ましくは０．０１０％以上である。 <C: 0.03% or less>
The C content is limited to 0.03% or less in order to ensure the corrosion resistance of the duplex stainless steel. When C exceeds 0.03%, Cr carbide is generated during hot rolling, so that corrosion resistance and toughness deteriorate. From such a viewpoint, the preferable C content is 0.025% or less, and more preferably 0.022% or less. On the other hand, since extremely reducing the C content significantly increases the cost, it is preferably 0.001% or more, and more preferably 0.010% or more.
＜Ｓｉ：０．１～１．０％＞
Ｓｉは、脱酸のため０．１％以上添加される。しかしながら１．０％を超えてＳｉが添加されると靱性が劣化する。そのため、上限を１．０％とする。当該観点から、Ｓｉ含有量の好ましい範囲は０．２～０．５％である。 <Si: 0.1 to 1.0%>
Si is added in an amount of 0.1% or more for deoxidation. However, when Si exceeds 1.0%, toughness deteriorates. Therefore, the upper limit is made 1.0%. From this viewpoint, the preferable range of the Si content is 0.2 to 0.5%.
Ｓｉは、脱酸のため０．１％以上添加される。しかしながら１．０％を超えてＳｉが添加されると靱性が劣化する。そのため、上限を１．０％とする。当該観点から、Ｓｉ含有量の好ましい範囲は０．２～０．５％である。 <Si: 0.1 to 1.0%>
Si is added in an amount of 0.1% or more for deoxidation. However, when Si exceeds 1.0%, toughness deteriorates. Therefore, the upper limit is made 1.0%. From this viewpoint, the preferable range of the Si content is 0.2 to 0.5%.
＜Ｍｎ：１．０～７．０％＞
Ｍｎは、二相ステンレス鋼中のオーステナイト相を増加させ、また窒素の固溶度を上げＣｒ窒化物の析出を抑制するので、１．０％以上添加される。しかしながら、７．０％を超えてＭｎが添加されると圧延まま材の耐食性が劣化する。そのため、上限を７．０％とする。好ましい範囲は２．０～４．０％であり、更に好ましい範囲は２．０％超～３．０％未満である。 <Mn: 1.0 to 7.0%>
Mn increases the austenite phase in the duplex stainless steel, increases the solid solubility of nitrogen, and suppresses the precipitation of Cr nitride, so 1.0% or more is added. However, if Mn is added over 7.0%, the corrosion resistance of the rolled material deteriorates. Therefore, the upper limit is set to 7.0%. A preferred range is 2.0 to 4.0%, and a more preferred range is more than 2.0% to less than 3.0%.
Ｍｎは、二相ステンレス鋼中のオーステナイト相を増加させ、また窒素の固溶度を上げＣｒ窒化物の析出を抑制するので、１．０％以上添加される。しかしながら、７．０％を超えてＭｎが添加されると圧延まま材の耐食性が劣化する。そのため、上限を７．０％とする。好ましい範囲は２．０～４．０％であり、更に好ましい範囲は２．０％超～３．０％未満である。 <Mn: 1.0 to 7.0%>
Mn increases the austenite phase in the duplex stainless steel, increases the solid solubility of nitrogen, and suppresses the precipitation of Cr nitride, so 1.0% or more is added. However, if Mn is added over 7.0%, the corrosion resistance of the rolled material deteriorates. Therefore, the upper limit is set to 7.0%. A preferred range is 2.0 to 4.0%, and a more preferred range is more than 2.0% to less than 3.0%.
＜Ｐ：０．０５％以下＞＜Ｓ：０．００５％以下＞
Ｐは、原料から不可避に混入する元素であり、熱間加工性および靱性を劣化させるため、材質上その含有量は少ないほど良く、０．０５％以下に制限される。好ましいＰ含有量は０．０３％以下である。なお、過度の低減は精錬コストの増加に繋がるため、下限を０．００５％とすることが好ましい。
Ｓは、原料から不可避に混入する元素であり、熱間加工性、靱性および耐食性を劣化させるため、材質上その含有量は少ないほど良く、０．００５％以下に制限される。好ましいＳ含有量は０．００２０％以下である。なお、過度の低減は精錬コストの増加に繋がるため、下限を０．０００２％とすることが好ましい。 <P: 0.05% or less><S: 0.005% or less>
P is an element that is inevitably mixed from the raw material, and deteriorates hot workability and toughness. Therefore, the content is preferably as small as possible, and is limited to 0.05% or less. A preferable P content is 0.03% or less. In addition, since excessive reduction leads to the increase in refining cost, it is preferable to make a minimum into 0.005%.
S is an element that is inevitably mixed from the raw material and degrades hot workability, toughness, and corrosion resistance. Therefore, the content is preferably as small as possible, and is limited to 0.005% or less. A preferable S content is 0.0020% or less. In addition, since excessive reduction leads to the increase in refining cost, it is preferable to make a minimum into 0.0002%.
Ｐは、原料から不可避に混入する元素であり、熱間加工性および靱性を劣化させるため、材質上その含有量は少ないほど良く、０．０５％以下に制限される。好ましいＰ含有量は０．０３％以下である。なお、過度の低減は精錬コストの増加に繋がるため、下限を０．００５％とすることが好ましい。
Ｓは、原料から不可避に混入する元素であり、熱間加工性、靱性および耐食性を劣化させるため、材質上その含有量は少ないほど良く、０．００５％以下に制限される。好ましいＳ含有量は０．００２０％以下である。なお、過度の低減は精錬コストの増加に繋がるため、下限を０．０００２％とすることが好ましい。 <P: 0.05% or less><S: 0.005% or less>
P is an element that is inevitably mixed from the raw material, and deteriorates hot workability and toughness. Therefore, the content is preferably as small as possible, and is limited to 0.05% or less. A preferable P content is 0.03% or less. In addition, since excessive reduction leads to the increase in refining cost, it is preferable to make a minimum into 0.005%.
S is an element that is inevitably mixed from the raw material and degrades hot workability, toughness, and corrosion resistance. Therefore, the content is preferably as small as possible, and is limited to 0.005% or less. A preferable S content is 0.0020% or less. In addition, since excessive reduction leads to the increase in refining cost, it is preferable to make a minimum into 0.0002%.
＜Ｃｒ：２０．５～２４．０％＞
Ｃｒは、耐食性を確保するために基本的に必要な元素であり、比較的安価な合金である。特に本実施形態ではＳＵＳ３０４と同等またはそれ以上の耐食性を確保するためには、析出による鋭敏化により生じる耐食性低下をも補償した成分系にすべきとの観点から、Ｃｒ含有量を高めることが有効である。本実施形態では２０．５％以上Ｃｒを含有させる。一方、Ｃｒはフェライト生成元素である上、過度の添加はＣｒ窒化物の生成を促す。そのため、２４．０％を超えて含有させるとオーステナイトの確保が困難となる。さらに、過度の添加により後述するＮｐｒｅを低減するためにＮｉ等を多く投入する必要が出てくることから、Ｃｒの含有量を２０．５％以上２４．０％以下とする。これらの観点から、Ｃｒ含有量の好ましい範囲は２１．０～２３．０％未満である。 <Cr: 20.5 to 24.0%>
Cr is an element basically necessary for ensuring corrosion resistance, and is a relatively inexpensive alloy. In particular, in this embodiment, in order to ensure the corrosion resistance equivalent to or higher than that of SUS304, it is effective to increase the Cr content from the viewpoint that the component system should also compensate for the corrosion resistance degradation caused by sensitization due to precipitation. It is. In this embodiment, 20.5% or more of Cr is contained. On the other hand, Cr is a ferrite-forming element, and excessive addition promotes the formation of Cr nitride. Therefore, if the content exceeds 24.0%, it becomes difficult to secure austenite. Furthermore, since it is necessary to add a large amount of Ni or the like in order to reduce Npre, which will be described later, due to excessive addition, the Cr content is set to 20.5% or more and 24.0% or less. From these viewpoints, the preferable range of the Cr content is 21.0 to less than 23.0%.
Ｃｒは、耐食性を確保するために基本的に必要な元素であり、比較的安価な合金である。特に本実施形態ではＳＵＳ３０４と同等またはそれ以上の耐食性を確保するためには、析出による鋭敏化により生じる耐食性低下をも補償した成分系にすべきとの観点から、Ｃｒ含有量を高めることが有効である。本実施形態では２０．５％以上Ｃｒを含有させる。一方、Ｃｒはフェライト生成元素である上、過度の添加はＣｒ窒化物の生成を促す。そのため、２４．０％を超えて含有させるとオーステナイトの確保が困難となる。さらに、過度の添加により後述するＮｐｒｅを低減するためにＮｉ等を多く投入する必要が出てくることから、Ｃｒの含有量を２０．５％以上２４．０％以下とする。これらの観点から、Ｃｒ含有量の好ましい範囲は２１．０～２３．０％未満である。 <Cr: 20.5 to 24.0%>
Cr is an element basically necessary for ensuring corrosion resistance, and is a relatively inexpensive alloy. In particular, in this embodiment, in order to ensure the corrosion resistance equivalent to or higher than that of SUS304, it is effective to increase the Cr content from the viewpoint that the component system should also compensate for the corrosion resistance degradation caused by sensitization due to precipitation. It is. In this embodiment, 20.5% or more of Cr is contained. On the other hand, Cr is a ferrite-forming element, and excessive addition promotes the formation of Cr nitride. Therefore, if the content exceeds 24.0%, it becomes difficult to secure austenite. Furthermore, since it is necessary to add a large amount of Ni or the like in order to reduce Npre, which will be described later, due to excessive addition, the Cr content is set to 20.5% or more and 24.0% or less. From these viewpoints, the preferable range of the Cr content is 21.0 to less than 23.0%.
＜Ｎｉ：１．５～５．０％＞
Ｎｉは、二相ステンレス鋼中のオーステナイト相を増加させること、フェライト相の靱性を向上させること、更に各種酸に対する耐食性を改善するのに有効な元素である上、後述するＮｐｒｅ低減のために有効な元素である。このような観点からＮｉは１．５％以上添加させるが、高価な合金であるため本発明では可能な限り抑制し５．０％以下とする。
好ましい範囲は２．０以上、４．０％未満である。 <Ni: 1.5-5.0%>
Ni is an element effective for increasing the austenite phase in the duplex stainless steel, improving the toughness of the ferrite phase, and further improving the corrosion resistance against various acids, and is effective for reducing Npre described later. Element. From this point of view, Ni is added in an amount of 1.5% or more. However, since it is an expensive alloy, it is suppressed as much as possible to 5.0% or less in the present invention.
A preferable range is 2.0 or more and less than 4.0%.
Ｎｉは、二相ステンレス鋼中のオーステナイト相を増加させること、フェライト相の靱性を向上させること、更に各種酸に対する耐食性を改善するのに有効な元素である上、後述するＮｐｒｅ低減のために有効な元素である。このような観点からＮｉは１．５％以上添加させるが、高価な合金であるため本発明では可能な限り抑制し５．０％以下とする。
好ましい範囲は２．０以上、４．０％未満である。 <Ni: 1.5-5.0%>
Ni is an element effective for increasing the austenite phase in the duplex stainless steel, improving the toughness of the ferrite phase, and further improving the corrosion resistance against various acids, and is effective for reducing Npre described later. Element. From this point of view, Ni is added in an amount of 1.5% or more. However, since it is an expensive alloy, it is suppressed as much as possible to 5.0% or less in the present invention.
A preferable range is 2.0 or more and less than 4.0%.
＜Ｍｏ：１．０％以下＞
Ｍｏは、ステンレス鋼の耐食性を大きく高める非常に有効な元素であるが、非常に高価な元素であるため、その含有量を１．０％以下と規定する。なお、耐食性とコストのバランスを考慮すると、Ｍｏ含有量の好ましい範囲は０．１～０．５％未満である。 <Mo: 1.0% or less>
Mo is a very effective element that greatly enhances the corrosion resistance of stainless steel, but since it is a very expensive element, its content is defined as 1.0% or less. In consideration of the balance between corrosion resistance and cost, the preferable range of the Mo content is 0.1 to less than 0.5%.
Ｍｏは、ステンレス鋼の耐食性を大きく高める非常に有効な元素であるが、非常に高価な元素であるため、その含有量を１．０％以下と規定する。なお、耐食性とコストのバランスを考慮すると、Ｍｏ含有量の好ましい範囲は０．１～０．５％未満である。 <Mo: 1.0% or less>
Mo is a very effective element that greatly enhances the corrosion resistance of stainless steel, but since it is a very expensive element, its content is defined as 1.0% or less. In consideration of the balance between corrosion resistance and cost, the preferable range of the Mo content is 0.1 to less than 0.5%.
＜Ｃｕ：２．０％以下＞
Ｃｕは、Ｎｉと同様二相ステンレス鋼中のオーステナイト相を増加させること、およびフェライト相の靱性を向上させること、更に各種酸に対する耐食性を改善するのに有効な元素であり、かつＮｉと比べて安価な合金であるため、０．５％以上含有させることが好ましい。しかし、２．０％を越えて含有させると窒化物析出が促進されて後述するＮｐｒｅを高めるため、Ｃｕ含有量の上限を２．０％とする。なお、好ましい上限は１．２％である。 <Cu: 2.0% or less>
Cu is an element effective for increasing the austenite phase in the duplex stainless steel and improving the toughness of the ferrite phase as well as Ni, and further improving the corrosion resistance against various acids, as compared to Ni. Since it is an inexpensive alloy, it is preferable to contain 0.5% or more. However, if the content exceeds 2.0%, nitride precipitation is promoted and Npre described later is increased, so the upper limit of the Cu content is set to 2.0%. A preferred upper limit is 1.2%.
Ｃｕは、Ｎｉと同様二相ステンレス鋼中のオーステナイト相を増加させること、およびフェライト相の靱性を向上させること、更に各種酸に対する耐食性を改善するのに有効な元素であり、かつＮｉと比べて安価な合金であるため、０．５％以上含有させることが好ましい。しかし、２．０％を越えて含有させると窒化物析出が促進されて後述するＮｐｒｅを高めるため、Ｃｕ含有量の上限を２．０％とする。なお、好ましい上限は１．２％である。 <Cu: 2.0% or less>
Cu is an element effective for increasing the austenite phase in the duplex stainless steel and improving the toughness of the ferrite phase as well as Ni, and further improving the corrosion resistance against various acids, as compared to Ni. Since it is an inexpensive alloy, it is preferable to contain 0.5% or more. However, if the content exceeds 2.0%, nitride precipitation is promoted and Npre described later is increased, so the upper limit of the Cu content is set to 2.0%. A preferred upper limit is 1.2%.
＜Ｖ：０．０５～０．５％＞
Ｖは、微量添加によりＣｒ窒化物の析出を抑制することが出来る元素である。即ち、ＶはＣｒより窒素との親和力が高いため、Ｖ含有量を固溶レベルに留めれば、Ｎの活量を下げＣｒの窒化物の析出を遅延させることが出来る。そのためには０．０５％以上の添加が必要である。一方、０．５％を越えて添加させるとＶ窒化物の析出により靭性が低下するため、上限は０．５％とする。なお、これらの観点からＶ含有量の好ましい範囲は０．０６％～０．３０％である。 <V: 0.05 to 0.5%>
V is an element that can suppress the precipitation of Cr nitride by addition of a small amount. That is, since V has a higher affinity with nitrogen than Cr, if the V content is kept at a solid solution level, the activity of N can be lowered and the precipitation of Cr nitride can be delayed. For that purpose, addition of 0.05% or more is necessary. On the other hand, if added over 0.5%, the toughness decreases due to precipitation of V nitride, so the upper limit is made 0.5%. From these viewpoints, the preferable range of the V content is 0.06% to 0.30%.
Ｖは、微量添加によりＣｒ窒化物の析出を抑制することが出来る元素である。即ち、ＶはＣｒより窒素との親和力が高いため、Ｖ含有量を固溶レベルに留めれば、Ｎの活量を下げＣｒの窒化物の析出を遅延させることが出来る。そのためには０．０５％以上の添加が必要である。一方、０．５％を越えて添加させるとＶ窒化物の析出により靭性が低下するため、上限は０．５％とする。なお、これらの観点からＶ含有量の好ましい範囲は０．０６％～０．３０％である。 <V: 0.05 to 0.5%>
V is an element that can suppress the precipitation of Cr nitride by addition of a small amount. That is, since V has a higher affinity with nitrogen than Cr, if the V content is kept at a solid solution level, the activity of N can be lowered and the precipitation of Cr nitride can be delayed. For that purpose, addition of 0.05% or more is necessary. On the other hand, if added over 0.5%, the toughness decreases due to precipitation of V nitride, so the upper limit is made 0.5%. From these viewpoints, the preferable range of the V content is 0.06% to 0.30%.
＜Ａｌ：０．００３～０．０５０％＞
Ａｌは、鋼の脱酸のための重要な元素であり、鋼中の酸素を低減するために０．００３％以上の含有が必要である。なお、精錬コストを考慮すると０．０１０％以上とすることが好ましい。一方でＡｌはＮとの親和力が比較的大きな元素であり、過剰に添加するとＡｌＮを生じて母材の靭性を阻害する。その程度はＮ含有量にも依存するが、Ａｌが０．０５０％を越えると靭性低下が著しくなるため、その含有量の上限を０．０５０％と定める。好ましくは０．０３０％以下である。 <Al: 0.003 to 0.050%>
Al is an important element for deoxidation of steel, and it is necessary to contain 0.003% or more in order to reduce oxygen in the steel. In consideration of the refining cost, it is preferable to set it to 0.010% or more. On the other hand, Al is an element having a relatively large affinity with N, and if added excessively, AlN is generated and the toughness of the base material is inhibited. The degree depends on the N content, but if Al exceeds 0.050%, the toughness deteriorates remarkably, so the upper limit of the content is set to 0.050%. Preferably it is 0.030% or less.
Ａｌは、鋼の脱酸のための重要な元素であり、鋼中の酸素を低減するために０．００３％以上の含有が必要である。なお、精錬コストを考慮すると０．０１０％以上とすることが好ましい。一方でＡｌはＮとの親和力が比較的大きな元素であり、過剰に添加するとＡｌＮを生じて母材の靭性を阻害する。その程度はＮ含有量にも依存するが、Ａｌが０．０５０％を越えると靭性低下が著しくなるため、その含有量の上限を０．０５０％と定める。好ましくは０．０３０％以下である。 <Al: 0.003 to 0.050%>
Al is an important element for deoxidation of steel, and it is necessary to contain 0.003% or more in order to reduce oxygen in the steel. In consideration of the refining cost, it is preferable to set it to 0.010% or more. On the other hand, Al is an element having a relatively large affinity with N, and if added excessively, AlN is generated and the toughness of the base material is inhibited. The degree depends on the N content, but if Al exceeds 0.050%, the toughness deteriorates remarkably, so the upper limit of the content is set to 0.050%. Preferably it is 0.030% or less.
＜Ｏ：０．００７％以下＞
Ｏは、非金属介在物の代表である酸化物を構成する有害な元素であり、過剰な含有は靭性を阻害する。また粗大なクラスター状酸化物が生成すると表面疵の原因となる。このため、材質上その含有量は少ないほど良く、Ｏの上限を０．００７％とする。好ましくは０．００５％以下である。一方、含有量を極端に低減することは大幅なコストアップになるため、下限を０．０００５％とするのが好ましい。 <O: 0.007% or less>
O is a harmful element constituting an oxide that is representative of nonmetallic inclusions, and excessive inclusion inhibits toughness. In addition, the formation of coarse clustered oxides causes surface defects. For this reason, the lower the content, the better. The upper limit of O is 0.007%. Preferably it is 0.005% or less. On the other hand, since extremely reducing the content significantly increases the cost, the lower limit is preferably set to 0.0005%.
Ｏは、非金属介在物の代表である酸化物を構成する有害な元素であり、過剰な含有は靭性を阻害する。また粗大なクラスター状酸化物が生成すると表面疵の原因となる。このため、材質上その含有量は少ないほど良く、Ｏの上限を０．００７％とする。好ましくは０．００５％以下である。一方、含有量を極端に低減することは大幅なコストアップになるため、下限を０．０００５％とするのが好ましい。 <O: 0.007% or less>
O is a harmful element constituting an oxide that is representative of nonmetallic inclusions, and excessive inclusion inhibits toughness. In addition, the formation of coarse clustered oxides causes surface defects. For this reason, the lower the content, the better. The upper limit of O is 0.007%. Preferably it is 0.005% or less. On the other hand, since extremely reducing the content significantly increases the cost, the lower limit is preferably set to 0.0005%.
＜Ｎ：０．１０～０．２５％＞
Ｎは、オーステナイト相に固溶して強度、耐食性を高めると共に、二相ステンレス鋼中のオーステナイト相を増加させる有効な元素である。特にオーステナイト相の耐食性を高めるのに有効である。このため、Ｎは０．１０％以上含有される。一方、０．２５％を越えて含有させるとＣｒ窒化物の析出を促進するため、含有量の上限を０．２５％とする。なお、耐食性の向上ならびにＣｒ窒化物の析出の抑制の観点から、Ｎの好ましい含有量は０．１３～０．２０％である。 <N: 0.10 to 0.25%>
N is an effective element for increasing the austenite phase in the duplex stainless steel while increasing the strength and corrosion resistance by dissolving in the austenite phase. In particular, it is effective for enhancing the corrosion resistance of the austenite phase. For this reason, N is contained 0.10% or more. On the other hand, if the content exceeds 0.25%, precipitation of Cr nitride is promoted, so the upper limit of the content is made 0.25%. From the viewpoint of improving the corrosion resistance and suppressing the precipitation of Cr nitride, the preferable content of N is 0.13 to 0.20%.
Ｎは、オーステナイト相に固溶して強度、耐食性を高めると共に、二相ステンレス鋼中のオーステナイト相を増加させる有効な元素である。特にオーステナイト相の耐食性を高めるのに有効である。このため、Ｎは０．１０％以上含有される。一方、０．２５％を越えて含有させるとＣｒ窒化物の析出を促進するため、含有量の上限を０．２５％とする。なお、耐食性の向上ならびにＣｒ窒化物の析出の抑制の観点から、Ｎの好ましい含有量は０．１３～０．２０％である。 <N: 0.10 to 0.25%>
N is an effective element for increasing the austenite phase in the duplex stainless steel while increasing the strength and corrosion resistance by dissolving in the austenite phase. In particular, it is effective for enhancing the corrosion resistance of the austenite phase. For this reason, N is contained 0.10% or more. On the other hand, if the content exceeds 0.25%, precipitation of Cr nitride is promoted, so the upper limit of the content is made 0.25%. From the viewpoint of improving the corrosion resistance and suppressing the precipitation of Cr nitride, the preferable content of N is 0.13 to 0.20%.
また、本実施形態では、上記元素に加えて、Ｎｂを０．０２～０．１５％かつＮｂ×Ｎが０．００３～０．０１５（ここで、Ｎｂ、Ｎは夫々の含有量の質量％を表す）となるように添加することが好ましい。
ＮｂはＶと同様、Ｎの活量を下げ窒化物析出を抑制するのに有効な元素であるので、選択的に添加される。但し、Ｎとの親和力が比較的高く、少量の添加でもＮｂ窒化物を析出してしまうので取り扱いには注意する必要がある。そこで、Ｎｂを添加する場合には、固溶限以下の添加となるようＮとの関係式（下記（２）式）によって求められる上限までの添加とすることで、Ｖの窒化物抑制効果を更に補填することが出来る。この効果を得るためにはＮｂは０．０２％以上添加させることが好ましい。しかしながら過剰添加するとＮｂ窒化物が析出し、母材を含めた靱性を損ねるので、Ｎｂの添加量は０．１５％以下であることが好ましく、０．０８％以下であることがより好ましい。
更に、Ｎｂを添加する場合には、前述の添加範囲に加え、いわゆる固溶度積を求める下記（２）式による値が０．００３～０．０１５となるＮｂ添加とする。これにより、上記に示す効果を得、かつ靱性への悪影響を防ぐことができる。なお、下記（２）式において各元素名はその含有量の質量％を表す。
Ｎｂ×Ｎ ・・・ （２） In the present embodiment, in addition to the above elements, Nb is 0.02 to 0.15% and Nb × N is 0.003 to 0.015 (where Nb and N are the mass% of the respective contents) It is preferable to add so that it represents.
Nb, like V, is an element that is effective in reducing the N activity and suppressing nitride precipitation, so it is selectively added. However, since the affinity with N is relatively high and Nb nitride precipitates even when added in a small amount, it must be handled with care. Therefore, in the case of adding Nb, the effect of suppressing the nitride of V is obtained by adding up to the upper limit determined by the relational expression with N (the following formula (2)) so that the addition is below the solid solubility limit. Further compensation can be made. In order to obtain this effect, Nb is preferably added in an amount of 0.02% or more. However, if Nb nitride is added excessively, Nb nitride precipitates and the toughness including the base material is impaired. Therefore, the amount of Nb added is preferably 0.15% or less, and more preferably 0.08% or less.
Further, when Nb is added, in addition to the above-described addition range, Nb is added so that a value according to the following equation (2) for obtaining a so-called solid solubility product is 0.003 to 0.015. Thereby, the effect shown above can be acquired and the bad influence on toughness can be prevented. In addition, in the following (2) Formula, each element name represents the mass% of the content.
Nb × N (2)
ＮｂはＶと同様、Ｎの活量を下げ窒化物析出を抑制するのに有効な元素であるので、選択的に添加される。但し、Ｎとの親和力が比較的高く、少量の添加でもＮｂ窒化物を析出してしまうので取り扱いには注意する必要がある。そこで、Ｎｂを添加する場合には、固溶限以下の添加となるようＮとの関係式（下記（２）式）によって求められる上限までの添加とすることで、Ｖの窒化物抑制効果を更に補填することが出来る。この効果を得るためにはＮｂは０．０２％以上添加させることが好ましい。しかしながら過剰添加するとＮｂ窒化物が析出し、母材を含めた靱性を損ねるので、Ｎｂの添加量は０．１５％以下であることが好ましく、０．０８％以下であることがより好ましい。
更に、Ｎｂを添加する場合には、前述の添加範囲に加え、いわゆる固溶度積を求める下記（２）式による値が０．００３～０．０１５となるＮｂ添加とする。これにより、上記に示す効果を得、かつ靱性への悪影響を防ぐことができる。なお、下記（２）式において各元素名はその含有量の質量％を表す。
Ｎｂ×Ｎ ・・・ （２） In the present embodiment, in addition to the above elements, Nb is 0.02 to 0.15% and Nb × N is 0.003 to 0.015 (where Nb and N are the mass% of the respective contents) It is preferable to add so that it represents.
Nb, like V, is an element that is effective in reducing the N activity and suppressing nitride precipitation, so it is selectively added. However, since the affinity with N is relatively high and Nb nitride precipitates even when added in a small amount, it must be handled with care. Therefore, in the case of adding Nb, the effect of suppressing the nitride of V is obtained by adding up to the upper limit determined by the relational expression with N (the following formula (2)) so that the addition is below the solid solubility limit. Further compensation can be made. In order to obtain this effect, Nb is preferably added in an amount of 0.02% or more. However, if Nb nitride is added excessively, Nb nitride precipitates and the toughness including the base material is impaired. Therefore, the amount of Nb added is preferably 0.15% or less, and more preferably 0.08% or less.
Further, when Nb is added, in addition to the above-described addition range, Nb is added so that a value according to the following equation (2) for obtaining a so-called solid solubility product is 0.003 to 0.015. Thereby, the effect shown above can be acquired and the bad influence on toughness can be prevented. In addition, in the following (2) Formula, each element name represents the mass% of the content.
Nb × N (2)
さらに、本実施形態では熱間加工性の向上を図ることを目的とし、上記元素に加えて、Ｃａ：０．００５０％以下、Ｍｇ：０．００５０％以下、ＲＥＭ：０．０５０％以下、Ｂ：０．００４０％以下の１種または２種以上を必要に応じて選択的に添加してもよい。
Furthermore, in the present embodiment, for the purpose of improving hot workability, in addition to the above elements, Ca: 0.0050% or less, Mg: 0.0050% or less, REM: 0.050% or less, B : One or more of 0.0040% or less may be selectively added as necessary.
Ｂ，Ｃａ，Ｍｇ，ＲＥＭいずれも過剰に添加されることにより熱間加工性および靭性が低下するため、その含有量の上限を次のように定める。
ＣａとＭｇの上限は０．００５０％、Ｂの上限は０．００４０％、ＲＥＭの上限は０．０５０％である。好ましい含有量は、ＢとＣａについては０．０００５～０．００３０％、Ｍｇ：０．０００１～０．００２０％、ＲＥＭ：０．００５～０．０５０％である。ここでＲＥＭはＬａやＣｅ等のランタノイド系希土類元素の含有量の総和とする。 When B, Ca, Mg, and REM are all added excessively, the hot workability and toughness are lowered. Therefore, the upper limit of the content is determined as follows.
The upper limit of Ca and Mg is 0.0050%, the upper limit of B is 0.0040%, and the upper limit of REM is 0.050%. Preferred contents for B and Ca are 0.0005 to 0.0030%, Mg: 0.0001 to 0.0020%, and REM: 0.005 to 0.050%. Here, REM is the total content of lanthanoid rare earth elements such as La and Ce.
ＣａとＭｇの上限は０．００５０％、Ｂの上限は０．００４０％、ＲＥＭの上限は０．０５０％である。好ましい含有量は、ＢとＣａについては０．０００５～０．００３０％、Ｍｇ：０．０００１～０．００２０％、ＲＥＭ：０．００５～０．０５０％である。ここでＲＥＭはＬａやＣｅ等のランタノイド系希土類元素の含有量の総和とする。 When B, Ca, Mg, and REM are all added excessively, the hot workability and toughness are lowered. Therefore, the upper limit of the content is determined as follows.
The upper limit of Ca and Mg is 0.0050%, the upper limit of B is 0.0040%, and the upper limit of REM is 0.050%. Preferred contents for B and Ca are 0.0005 to 0.0030%, Mg: 0.0001 to 0.0020%, and REM: 0.005 to 0.050%. Here, REM is the total content of lanthanoid rare earth elements such as La and Ce.
さらに、本実施形態では、上記元素に加えて、Ｃｏを０．０２～１．００％添加してもよい。
Ｃｏは、二相ステンレス鋼の靭性と耐食性を高めるために有効な元素であり、選択的に添加される。Ｃｏの含有量は０．０２％以上が好ましい。一方、１．０％を越えてＣｏを含有させると、Ｃｏが高価な元素であるためにコストに見合った効果が発揮されないため、上限を１．０％と定める。Ｃｏを添加する場合の好ましい含有量は、０．０２～０．５％である。 Further, in the present embodiment, 0.02 to 1.00% of Co may be added in addition to the above elements.
Co is an element effective for enhancing the toughness and corrosion resistance of the duplex stainless steel, and is selectively added. The Co content is preferably 0.02% or more. On the other hand, if Co is contained exceeding 1.0%, Co is an expensive element and an effect commensurate with the cost cannot be exhibited, so the upper limit is set to 1.0%. A preferable content when Co is added is 0.02 to 0.5%.
Ｃｏは、二相ステンレス鋼の靭性と耐食性を高めるために有効な元素であり、選択的に添加される。Ｃｏの含有量は０．０２％以上が好ましい。一方、１．０％を越えてＣｏを含有させると、Ｃｏが高価な元素であるためにコストに見合った効果が発揮されないため、上限を１．０％と定める。Ｃｏを添加する場合の好ましい含有量は、０．０２～０．５％である。 Further, in the present embodiment, 0.02 to 1.00% of Co may be added in addition to the above elements.
Co is an element effective for enhancing the toughness and corrosion resistance of the duplex stainless steel, and is selectively added. The Co content is preferably 0.02% or more. On the other hand, if Co is contained exceeding 1.0%, Co is an expensive element and an effect commensurate with the cost cannot be exhibited, so the upper limit is set to 1.0%. A preferable content when Co is added is 0.02 to 0.5%.
さらに、本実施形態では、上記元素に加えて、Ｔｉ：０．０５％以下、Ｗ：１．０％以下、Ｓｎ：０．１％以下の１種または２種以上を必要に応じて選択的に添加してもよい。
Ｔｉは、添加によりＣやＳによる耐食性への悪影響を抑制することができるが、過剰に添加すると靱性低下を生じる等の悪影響が発生する。このため、選択的にＴｉを添加する場合の含有量は、０．０５％以下に制限することが好ましく、より好ましくは０．０２％以下である。
Ｗは、二相ステンレス鋼の耐食性を付加的に高めるために選択的に添加される元素であるが、高価な元素であり過剰添加はコスト増を招く。このためＷの含有量を１．０％以下に制限することが好ましく、より好ましくは０．８％以下である。
Ｓｎは耐酸性を付加的に向上させる選択的元素であり、熱間加工性の観点から０．１％を上限としてＳｎを添加することが出来る。なお、上限はより好ましくは０．０８％以下である。
なお、Ｔｉ、Ｗ、Ｓｎの上記効果を安定して発揮する好ましい含有量は、それぞれ０．００１％以上、０．０５％以上、０．０５％以上である。 Furthermore, in this embodiment, in addition to the above elements, one or more of Ti: 0.05% or less, W: 1.0% or less, and Sn: 0.1% or less are selectively selected as necessary. You may add to.
Ti can suppress the adverse effect on corrosion resistance due to C and S by addition, but if added excessively, adverse effects such as a decrease in toughness occur. Therefore, the content when Ti is selectively added is preferably limited to 0.05% or less, more preferably 0.02% or less.
W is an element that is selectively added to additionally enhance the corrosion resistance of the duplex stainless steel, but is an expensive element and excessive addition causes an increase in cost. Therefore, the W content is preferably limited to 1.0% or less, more preferably 0.8% or less.
Sn is a selective element that additionally improves acid resistance, and Sn can be added up to 0.1% from the viewpoint of hot workability. The upper limit is more preferably 0.08% or less.
In addition, preferable content which exhibits the said effect of Ti, W, and Sn stably is 0.001% or more, 0.05% or more, and 0.05% or more, respectively.
Ｔｉは、添加によりＣやＳによる耐食性への悪影響を抑制することができるが、過剰に添加すると靱性低下を生じる等の悪影響が発生する。このため、選択的にＴｉを添加する場合の含有量は、０．０５％以下に制限することが好ましく、より好ましくは０．０２％以下である。
Ｗは、二相ステンレス鋼の耐食性を付加的に高めるために選択的に添加される元素であるが、高価な元素であり過剰添加はコスト増を招く。このためＷの含有量を１．０％以下に制限することが好ましく、より好ましくは０．８％以下である。
Ｓｎは耐酸性を付加的に向上させる選択的元素であり、熱間加工性の観点から０．１％を上限としてＳｎを添加することが出来る。なお、上限はより好ましくは０．０８％以下である。
なお、Ｔｉ、Ｗ、Ｓｎの上記効果を安定して発揮する好ましい含有量は、それぞれ０．００１％以上、０．０５％以上、０．０５％以上である。 Furthermore, in this embodiment, in addition to the above elements, one or more of Ti: 0.05% or less, W: 1.0% or less, and Sn: 0.1% or less are selectively selected as necessary. You may add to.
Ti can suppress the adverse effect on corrosion resistance due to C and S by addition, but if added excessively, adverse effects such as a decrease in toughness occur. Therefore, the content when Ti is selectively added is preferably limited to 0.05% or less, more preferably 0.02% or less.
W is an element that is selectively added to additionally enhance the corrosion resistance of the duplex stainless steel, but is an expensive element and excessive addition causes an increase in cost. Therefore, the W content is preferably limited to 1.0% or less, more preferably 0.8% or less.
Sn is a selective element that additionally improves acid resistance, and Sn can be added up to 0.1% from the viewpoint of hot workability. The upper limit is more preferably 0.08% or less.
In addition, preferable content which exhibits the said effect of Ti, W, and Sn stably is 0.001% or more, 0.05% or more, and 0.05% or more, respectively.
次に、本実施形態に係る二相ステンレス鋼の組織について説明する。
本実施形態に係る二相ステンレス鋼において、良好な特性を得るためには、オーステナイト相面積率を４０～７０％の範囲にすることが必要である。４０％未満では靱性不良の問題が生じる。一方、７０％超では熱間加工性、応力腐食割れの問題が出てくる。また、オーステナイト相が過度に少なすぎる場合、また多すぎる場合ともに、耐食性が不良となる。なお、前述の各特性のバランスを考慮すると、オーステナイト相面積率を４５～６５％とすることが好ましい。 Next, the structure of the duplex stainless steel according to this embodiment will be described.
In the duplex stainless steel according to this embodiment, in order to obtain good characteristics, the austenite phase area ratio needs to be in the range of 40 to 70%. If it is less than 40%, the problem of poor toughness occurs. On the other hand, if it exceeds 70%, problems of hot workability and stress corrosion cracking appear. In addition, when the austenite phase is too small or too large, the corrosion resistance becomes poor. In consideration of the balance of the above-mentioned characteristics, the austenite phase area ratio is preferably 45 to 65%.
本実施形態に係る二相ステンレス鋼において、良好な特性を得るためには、オーステナイト相面積率を４０～７０％の範囲にすることが必要である。４０％未満では靱性不良の問題が生じる。一方、７０％超では熱間加工性、応力腐食割れの問題が出てくる。また、オーステナイト相が過度に少なすぎる場合、また多すぎる場合ともに、耐食性が不良となる。なお、前述の各特性のバランスを考慮すると、オーステナイト相面積率を４５～６５％とすることが好ましい。 Next, the structure of the duplex stainless steel according to this embodiment will be described.
In the duplex stainless steel according to this embodiment, in order to obtain good characteristics, the austenite phase area ratio needs to be in the range of 40 to 70%. If it is less than 40%, the problem of poor toughness occurs. On the other hand, if it exceeds 70%, problems of hot workability and stress corrosion cracking appear. In addition, when the austenite phase is too small or too large, the corrosion resistance becomes poor. In consideration of the balance of the above-mentioned characteristics, the austenite phase area ratio is preferably 45 to 65%.
次に、熱延ままで溶体化熱処理（固溶化熱処理）をせずに、７００℃で３分間等温熱処理した場合でもＣｒ窒化物析出による鋭敏化を極力抑制しうる鋼の規定として、本実施形態に係る二相ステンレス鋼においては、下記式（１）に示すＣｒ窒化物の析出開始温度計算値Ｎｐｒｅを９２０℃以下とする。
Ｎｐｒｅ＝１２Ｃｒ＋５０Ｓｉ＋３６Ｍｏ－２０Ｎｉ－１５Ｍｎ
＋２８Ｃｕ＋４７０Ｎ－２９０Ｃ＋６２０ ・・・・ （１）
Ｃｒ窒化物の析出を抑制するためには、Ｎを単に低減するだけではなく、Ｎ固溶限が大きいオーステナイト相を増加させることによりフェライト相中の固溶Ｎ量を減少させること、更にはＣｒ窒化物析出の駆動力を低減させる元素制御を行うことが重要である。
析出駆動力の大きさは析出開始温度と実際の温度との差で示される過冷度の大きさと対応していると考えられる。そこで、本発明者らは、析出開始温度をシミュレーション計算により求め、各成分のＣｒ窒化物の析出への寄与の大きさを定式化し、これを用いてＣｒ窒化物が析出し難い成分範囲を規定することを試みた。具体的には、熱力学データを用いたシミュレーション計算により添加元素の影響を算出し、更にこの添加元素の影響を実験にて確認し、上記（１）式を作成した。更に、この式（１）により算出された値と耐食性の実験結果との対応より、Ｎｐｒｅが９２０℃以下の場合、７００℃×３分間の熱処理による耐食性低下をほぼ抑制しうることを確認し、当該規定とした。つまり、化学ポテンシャル（エネルギー）の差（△Ｇ）である過冷度が大きいほど核生成が容易になることから、本実施形態では、式（１）の値（析出開始温度）を抑えることで化学ポテンシャルの差（△Ｇ）、つまり過冷度を低減させ、その結果、析出駆動力を低減させて耐食性の低下を抑制することが重要である。 Next, as a provision of steel that can suppress sensitization due to Cr nitride precipitation as much as possible even when isothermal heat treatment is performed at 700 ° C. for 3 minutes without performing solution heat treatment (solution heat treatment) with hot rolling, In the duplex stainless steel according to the embodiment, the Cr nitride precipitation start temperature calculation value Npre shown in the following formula (1) is set to 920 ° C. or less.
Npre = 12Cr + 50Si + 36Mo-20Ni-15Mn
+ 28Cu + 470N-290C + 620 (1)
In order to suppress the precipitation of Cr nitride, not only simply reducing N, but also reducing the amount of dissolved N in the ferrite phase by increasing the austenite phase having a large N solid solubility limit, and further Cr It is important to perform element control to reduce the driving force of nitride precipitation.
The magnitude of the precipitation driving force is considered to correspond to the magnitude of the degree of supercooling indicated by the difference between the precipitation start temperature and the actual temperature. Therefore, the present inventors obtain the precipitation start temperature by simulation calculation, formulate the magnitude of contribution of each component to Cr nitride precipitation, and use this to define the component range where Cr nitride is difficult to precipitate. Tried to do. Specifically, the influence of the additive element was calculated by simulation calculation using thermodynamic data, and the influence of the additive element was confirmed by experiment, and the above formula (1) was created. Furthermore, from the correspondence between the value calculated by this formula (1) and the experimental results of corrosion resistance, when Npre is 920 ° C. or less, it is confirmed that the corrosion resistance decrease due to heat treatment at 700 ° C. × 3 minutes can be substantially suppressed, This provision was adopted. That is, since the nucleation becomes easier as the degree of supercooling, which is the difference (ΔG) in chemical potential (energy), becomes larger, in this embodiment, by suppressing the value (precipitation start temperature) of Equation (1) It is important to reduce the difference in chemical potential (ΔG), that is, the degree of supercooling, and as a result, reduce the precipitation driving force to suppress the deterioration of corrosion resistance.
Ｎｐｒｅ＝１２Ｃｒ＋５０Ｓｉ＋３６Ｍｏ－２０Ｎｉ－１５Ｍｎ
＋２８Ｃｕ＋４７０Ｎ－２９０Ｃ＋６２０ ・・・・ （１）
Ｃｒ窒化物の析出を抑制するためには、Ｎを単に低減するだけではなく、Ｎ固溶限が大きいオーステナイト相を増加させることによりフェライト相中の固溶Ｎ量を減少させること、更にはＣｒ窒化物析出の駆動力を低減させる元素制御を行うことが重要である。
析出駆動力の大きさは析出開始温度と実際の温度との差で示される過冷度の大きさと対応していると考えられる。そこで、本発明者らは、析出開始温度をシミュレーション計算により求め、各成分のＣｒ窒化物の析出への寄与の大きさを定式化し、これを用いてＣｒ窒化物が析出し難い成分範囲を規定することを試みた。具体的には、熱力学データを用いたシミュレーション計算により添加元素の影響を算出し、更にこの添加元素の影響を実験にて確認し、上記（１）式を作成した。更に、この式（１）により算出された値と耐食性の実験結果との対応より、Ｎｐｒｅが９２０℃以下の場合、７００℃×３分間の熱処理による耐食性低下をほぼ抑制しうることを確認し、当該規定とした。つまり、化学ポテンシャル（エネルギー）の差（△Ｇ）である過冷度が大きいほど核生成が容易になることから、本実施形態では、式（１）の値（析出開始温度）を抑えることで化学ポテンシャルの差（△Ｇ）、つまり過冷度を低減させ、その結果、析出駆動力を低減させて耐食性の低下を抑制することが重要である。 Next, as a provision of steel that can suppress sensitization due to Cr nitride precipitation as much as possible even when isothermal heat treatment is performed at 700 ° C. for 3 minutes without performing solution heat treatment (solution heat treatment) with hot rolling, In the duplex stainless steel according to the embodiment, the Cr nitride precipitation start temperature calculation value Npre shown in the following formula (1) is set to 920 ° C. or less.
Npre = 12Cr + 50Si + 36Mo-20Ni-15Mn
+ 28Cu + 470N-290C + 620 (1)
In order to suppress the precipitation of Cr nitride, not only simply reducing N, but also reducing the amount of dissolved N in the ferrite phase by increasing the austenite phase having a large N solid solubility limit, and further Cr It is important to perform element control to reduce the driving force of nitride precipitation.
The magnitude of the precipitation driving force is considered to correspond to the magnitude of the degree of supercooling indicated by the difference between the precipitation start temperature and the actual temperature. Therefore, the present inventors obtain the precipitation start temperature by simulation calculation, formulate the magnitude of contribution of each component to Cr nitride precipitation, and use this to define the component range where Cr nitride is difficult to precipitate. Tried to do. Specifically, the influence of the additive element was calculated by simulation calculation using thermodynamic data, and the influence of the additive element was confirmed by experiment, and the above formula (1) was created. Furthermore, from the correspondence between the value calculated by this formula (1) and the experimental results of corrosion resistance, when Npre is 920 ° C. or less, it is confirmed that the corrosion resistance decrease due to heat treatment at 700 ° C. × 3 minutes can be substantially suppressed, This provision was adopted. That is, since the nucleation becomes easier as the degree of supercooling, which is the difference (ΔG) in chemical potential (energy), becomes larger, in this embodiment, by suppressing the value (precipitation start temperature) of Equation (1) It is important to reduce the difference in chemical potential (ΔG), that is, the degree of supercooling, and as a result, reduce the precipitation driving force to suppress the deterioration of corrosion resistance.
本実施形態に係るクラッド鋼板は、上述してきた二相ステンレス鋼を合わせ材とし、炭素鋼または合金鋼を母材とするクラッド鋼板である。
クラッド鋼板の母材は、合わせ材として用いられる二相ステンレス鋼よりもＣ含有量が多いものである。母材としては、普通鋼（炭素鋼）もしくは合金鋼が用いられるが、本実施形態においても、母材の材料は目的用途に応じて適宜選択して使用でき、特に限定されるものではない。また、合金鋼としては、ステンレス鋼を除くものであることが好ましく、低合金鋼、ニッケル鋼、マンガン鋼、クロムモリブデン鋼、高速度鋼からなる群より選択される１種以上などが挙げられるが、これらに限定されるものではない。 The clad steel plate according to the present embodiment is a clad steel plate using the above-described duplex stainless steel as a combination material and carbon steel or alloy steel as a base material.
The base material of the clad steel plate has a higher C content than the duplex stainless steel used as a laminated material. As the base material, ordinary steel (carbon steel) or alloy steel is used, but also in this embodiment, the material of the base material can be appropriately selected and used according to the intended use, and is not particularly limited. The alloy steel is preferably one excluding stainless steel, and includes one or more selected from the group consisting of low alloy steel, nickel steel, manganese steel, chromium molybdenum steel, and high speed steel. However, it is not limited to these.
クラッド鋼板の母材は、合わせ材として用いられる二相ステンレス鋼よりもＣ含有量が多いものである。母材としては、普通鋼（炭素鋼）もしくは合金鋼が用いられるが、本実施形態においても、母材の材料は目的用途に応じて適宜選択して使用でき、特に限定されるものではない。また、合金鋼としては、ステンレス鋼を除くものであることが好ましく、低合金鋼、ニッケル鋼、マンガン鋼、クロムモリブデン鋼、高速度鋼からなる群より選択される１種以上などが挙げられるが、これらに限定されるものではない。 The clad steel plate according to the present embodiment is a clad steel plate using the above-described duplex stainless steel as a combination material and carbon steel or alloy steel as a base material.
The base material of the clad steel plate has a higher C content than the duplex stainless steel used as a laminated material. As the base material, ordinary steel (carbon steel) or alloy steel is used, but also in this embodiment, the material of the base material can be appropriately selected and used according to the intended use, and is not particularly limited. The alloy steel is preferably one excluding stainless steel, and includes one or more selected from the group consisting of low alloy steel, nickel steel, manganese steel, chromium molybdenum steel, and high speed steel. However, it is not limited to these.
次に、本実施形態に係る二相ステンレス鋼は、線状加熱時の耐食性低下を抑制しうる特性指標として、７００℃で３分間の等温熱処理した後の、合わせ材（二相ステンレス鋼）のみを切り出し電解抽出残渣分析を行って求めた析出物中のクロム量が０．０５％以下であることを特徴とする。
７００℃付近はクロム窒化物が最も大量に析出する温度域であり、線状加熱によって当該温度域に晒される最大レベルの時間として３分を規定した。この熱処理を行った後の耐食性の低下を評価して熱処理後でも耐食性低下を生じていないことを確認することによって、耐食性の課題を回避したことを確認できる。
以下、クロム量の測定について本発明者らが採用した具体的手段を説明する。 Next, the duplex stainless steel according to this embodiment is a laminated material (duplex stainless steel) after being subjected to an isothermal heat treatment at 700 ° C. for 3 minutes as a characteristic index capable of suppressing a decrease in corrosion resistance during linear heating. It is characterized by the fact that the chromium content in the precipitate obtained by cutting out only this and conducting the electrolytic extraction residue analysis is 0.05% or less.
The vicinity of 700 ° C. is a temperature range in which chromium nitride is precipitated in the largest amount, and 3 minutes is defined as the maximum level of time that is exposed to the temperature range by linear heating. By evaluating the decrease in corrosion resistance after this heat treatment and confirming that no deterioration in corrosion resistance has occurred even after the heat treatment, it can be confirmed that the problem of corrosion resistance has been avoided.
Hereinafter, specific means adopted by the present inventors for the measurement of the chromium content will be described.
７００℃付近はクロム窒化物が最も大量に析出する温度域であり、線状加熱によって当該温度域に晒される最大レベルの時間として３分を規定した。この熱処理を行った後の耐食性の低下を評価して熱処理後でも耐食性低下を生じていないことを確認することによって、耐食性の課題を回避したことを確認できる。
以下、クロム量の測定について本発明者らが採用した具体的手段を説明する。 Next, the duplex stainless steel according to this embodiment is a laminated material (duplex stainless steel) after being subjected to an isothermal heat treatment at 700 ° C. for 3 minutes as a characteristic index capable of suppressing a decrease in corrosion resistance during linear heating. It is characterized by the fact that the chromium content in the precipitate obtained by cutting out only this and conducting the electrolytic extraction residue analysis is 0.05% or less.
The vicinity of 700 ° C. is a temperature range in which chromium nitride is precipitated in the largest amount, and 3 minutes is defined as the maximum level of time that is exposed to the temperature range by linear heating. By evaluating the decrease in corrosion resistance after this heat treatment and confirming that no deterioration in corrosion resistance has occurred even after the heat treatment, it can be confirmed that the problem of corrosion resistance has been avoided.
Hereinafter, specific means adopted by the present inventors for the measurement of the chromium content will be described.
析出物中のクロム量は、本発明者らは以下の手順（電解抽出残渣分析法）で求めたが、クロム量の測定は当該手順に限らず、同様の手法を用いれば良い。
（１）７００℃で３分間の等温熱処理後の供試材から合わせ材のみを取り出し、表面を＃５００で研磨する。
（２）３ｇ試料を分取し、非水溶液中（３％マレイン酸＋１％テトラメチルアンモニウムクロライド＋残部メタノール）で電解（１００ｍＶ ｖｓ ＳＣＥ定電位電解）してマトリックスを溶解する。
（３）０．２μｍ穴径のフィルターで残渣（＝析出物）を濾過し、析出物を抽出する。
（４）残渣の化学組成を分析し、そのクロム含有量を求める。この残渣中のクロム含有量を元の鋼材量（３ｇ）で除し、％表示したものを析出物中のクロム量とする。
そして、この析出物中のクロム量が０．０５％以下の場合は耐食性の低下がほとんど無いことが分かった。 The present inventors determined the amount of chromium in the precipitate by the following procedure (electrolytic extraction residue analysis method), but the measurement of the amount of chromium is not limited to this procedure, and a similar method may be used.
(1) Take out only the laminated material from the specimen after the isothermal heat treatment at 700 ° C. for 3 minutes, and polish the surface with # 500.
(2) A 3 g sample is taken and electrolyzed (100 mV vs SCE constant potential electrolysis) in a non-aqueous solution (3% maleic acid + 1% tetramethylammonium chloride + remaining methanol) to dissolve the matrix.
(3) The residue (= precipitate) is filtered with a 0.2 μm hole diameter filter, and the precipitate is extracted.
(4) Analyze the chemical composition of the residue and determine its chromium content. The chromium content in the residue is divided by the original steel material amount (3 g), and the amount expressed in% is defined as the chromium content in the precipitate.
And when the chromium amount in this deposit was 0.05% or less, it turned out that there is almost no fall of corrosion resistance.
（１）７００℃で３分間の等温熱処理後の供試材から合わせ材のみを取り出し、表面を＃５００で研磨する。
（２）３ｇ試料を分取し、非水溶液中（３％マレイン酸＋１％テトラメチルアンモニウムクロライド＋残部メタノール）で電解（１００ｍＶ ｖｓ ＳＣＥ定電位電解）してマトリックスを溶解する。
（３）０．２μｍ穴径のフィルターで残渣（＝析出物）を濾過し、析出物を抽出する。
（４）残渣の化学組成を分析し、そのクロム含有量を求める。この残渣中のクロム含有量を元の鋼材量（３ｇ）で除し、％表示したものを析出物中のクロム量とする。
そして、この析出物中のクロム量が０．０５％以下の場合は耐食性の低下がほとんど無いことが分かった。 The present inventors determined the amount of chromium in the precipitate by the following procedure (electrolytic extraction residue analysis method), but the measurement of the amount of chromium is not limited to this procedure, and a similar method may be used.
(1) Take out only the laminated material from the specimen after the isothermal heat treatment at 700 ° C. for 3 minutes, and polish the surface with # 500.
(2) A 3 g sample is taken and electrolyzed (100 mV vs SCE constant potential electrolysis) in a non-aqueous solution (3% maleic acid + 1% tetramethylammonium chloride + remaining methanol) to dissolve the matrix.
(3) The residue (= precipitate) is filtered with a 0.2 μm hole diameter filter, and the precipitate is extracted.
(4) Analyze the chemical composition of the residue and determine its chromium content. The chromium content in the residue is divided by the original steel material amount (3 g), and the amount expressed in% is defined as the chromium content in the precipitate.
And when the chromium amount in this deposit was 0.05% or less, it turned out that there is almost no fall of corrosion resistance.
次いで本実施形態に係るクラッド鋼板の製造方法について説明する。
本実施形態に係るクラッド鋼板の製造方法は、上述してきた本実施形態の二相ステンレス鋼を合わせ材とし、当該合わせ材と、普通鋼もしくは合金鋼からなる母材とを組み合わせた被圧延素材を、９００℃以上で熱間圧延し、その後の冷却時において９００～６００℃までの通過時間を６０秒以上１５分以内とし、前記冷却後はそのまま熱処理せずに、つまり熱延まま材として製品（クラッド鋼板）とすることを特徴とする。
以下、製造条件の限定理由について詳細に説明する。 Next, a method for manufacturing a clad steel plate according to this embodiment will be described.
The manufacturing method of the clad steel plate according to the present embodiment uses the duplex stainless steel of the present embodiment described above as a combined material, and a rolled material obtained by combining the combined material and a base material made of ordinary steel or alloy steel. , Hot-rolled at 900 ° C. or higher, and at the time of subsequent cooling, the passing time from 900 to 600 ° C. is 60 seconds or longer and within 15 minutes. Clad steel plate).
Hereinafter, the reasons for limiting the manufacturing conditions will be described in detail.
本実施形態に係るクラッド鋼板の製造方法は、上述してきた本実施形態の二相ステンレス鋼を合わせ材とし、当該合わせ材と、普通鋼もしくは合金鋼からなる母材とを組み合わせた被圧延素材を、９００℃以上で熱間圧延し、その後の冷却時において９００～６００℃までの通過時間を６０秒以上１５分以内とし、前記冷却後はそのまま熱処理せずに、つまり熱延まま材として製品（クラッド鋼板）とすることを特徴とする。
以下、製造条件の限定理由について詳細に説明する。 Next, a method for manufacturing a clad steel plate according to this embodiment will be described.
The manufacturing method of the clad steel plate according to the present embodiment uses the duplex stainless steel of the present embodiment described above as a combined material, and a rolled material obtained by combining the combined material and a base material made of ordinary steel or alloy steel. , Hot-rolled at 900 ° C. or higher, and at the time of subsequent cooling, the passing time from 900 to 600 ° C. is 60 seconds or longer and within 15 minutes. Clad steel plate).
Hereinafter, the reasons for limiting the manufacturing conditions will be described in detail.
本実施形態のクラッド鋼板は、以下のような工程で製造される。
まず、所定の厚さの母材と上述した本実施形態に係る二相ステンレス鋼からなる合わせ材とを用意し、それぞれ接合面を清浄にした上で重ね合わせ、四周（重ね合わせ面の外周）を溶接により接合し、スラブ（被圧延素材）を組み立てる。なお、この際、重ね合わせ面の接合強度を高めるために真空脱ガスなどが適宜実施されてもよい。
なお、母材としては、普通鋼（炭素鋼）もしくは合金鋼が用いられるが、上述したように母材の材料は目的用途に応じて適宜選択して使用でき、特に限定されるものではない。
合金鋼としては、ステンレス鋼を除くものであることが好ましく、低合金鋼、ニッケル鋼、マンガン鋼、クロムモリブデン鋼、高速度鋼からなる群より選択される１種以上などが挙げられる。 The clad steel plate of this embodiment is manufactured by the following processes.
First, a base material having a predetermined thickness and a laminated material made of the duplex stainless steel according to the above-described embodiment are prepared, and the respective joint surfaces are cleaned and overlapped, and four rounds (the outer circumference of the superposed surface). Are joined by welding to slab (rolled material). At this time, vacuum degassing or the like may be performed as appropriate in order to increase the bonding strength of the overlapping surfaces.
As the base material, ordinary steel (carbon steel) or alloy steel is used, but as described above, the material of the base material can be appropriately selected and used according to the intended use, and is not particularly limited.
The alloy steel preferably excludes stainless steel, and includes one or more selected from the group consisting of low alloy steel, nickel steel, manganese steel, chromium molybdenum steel, and high speed steel.
まず、所定の厚さの母材と上述した本実施形態に係る二相ステンレス鋼からなる合わせ材とを用意し、それぞれ接合面を清浄にした上で重ね合わせ、四周（重ね合わせ面の外周）を溶接により接合し、スラブ（被圧延素材）を組み立てる。なお、この際、重ね合わせ面の接合強度を高めるために真空脱ガスなどが適宜実施されてもよい。
なお、母材としては、普通鋼（炭素鋼）もしくは合金鋼が用いられるが、上述したように母材の材料は目的用途に応じて適宜選択して使用でき、特に限定されるものではない。
合金鋼としては、ステンレス鋼を除くものであることが好ましく、低合金鋼、ニッケル鋼、マンガン鋼、クロムモリブデン鋼、高速度鋼からなる群より選択される１種以上などが挙げられる。 The clad steel plate of this embodiment is manufactured by the following processes.
First, a base material having a predetermined thickness and a laminated material made of the duplex stainless steel according to the above-described embodiment are prepared, and the respective joint surfaces are cleaned and overlapped, and four rounds (the outer circumference of the superposed surface). Are joined by welding to slab (rolled material). At this time, vacuum degassing or the like may be performed as appropriate in order to increase the bonding strength of the overlapping surfaces.
As the base material, ordinary steel (carbon steel) or alloy steel is used, but as described above, the material of the base material can be appropriately selected and used according to the intended use, and is not particularly limited.
The alloy steel preferably excludes stainless steel, and includes one or more selected from the group consisting of low alloy steel, nickel steel, manganese steel, chromium molybdenum steel, and high speed steel.
次に、このスラブに素材加熱工程を行った後、熱間圧延を施してクラッド鋼板が製造される。なお、素材加熱工程とは、熱間圧延を施すためにスラブを再加熱する工程であって、その加熱温度は特に限定しないが、圧延温度の確保とコストの観点から１０００～１２００℃とすることが好ましい。
また、この熱間圧延の温度履歴は本発明におけるクラッド鋼板の製造条件の規定に関して重要因子である。まず、熱間圧延温度、つまり熱間圧延の仕上げ温度は９００℃以上とする。これにより、本実施形態の合わせ材である二相ステンレス鋼において熱間圧延時における窒化物の析出を抑制することができる。次に、熱間圧延後の冷却時において、９００～６００℃の範囲の通過時間を６０秒以上１５分以内とする。この９００℃～６００℃の温度域は窒化物の析出速度が最も速い温度域である。冷却過程において当該温度域を１５分以上掛けて通過させた場合は当該冷却時に窒化物の析出、鋭敏化による耐食性低下が無視できないレベルになる。一方、通過時間が６０秒未満の急冷の場合は、その時点で析出は生じないが、７００℃×３分の熱処理によって析出が促進されることが判明した。つまり、通過時間を非常に短くして急冷の形態としてしまうと、熱間圧延後の冷却段階では窒化物の析出は防げるものの、クラッド鋼板に曲げ加工を施す際に行う線状加熱（通常、１０００℃程度まで加熱）によって窒化物が析出してしまうおそれがある。これは、熱間圧延後の急冷によって、圧延時に生じた転位が多く残存し、それが線状加熱に相当する７００℃×３分間の熱処理時に析出核となるためと推定される。
すなわち、本実施形態に係る製造方法では、熱間圧延後の冷却時において、窒化物が最も析出しやすい（析出速度が速い）９００～６００℃の温度域の通過時間を６０秒以上１５分以内とすることによって、冷却時の窒化物の析出を抑制するとともに、その後工程である線状加熱による曲げ加工を施す際においても窒化物の析出を抑制することができる。
なお、通過時間は６０秒以上ならば短いほど耐食性を改善出来るので、好ましくは５分以下、更に好ましくは３分以下とする。 Next, after carrying out a raw material heating process to this slab, it hot-rolls and a clad steel plate is manufactured. The material heating step is a step of reheating the slab in order to perform hot rolling, and the heating temperature is not particularly limited, but should be 1000 to 1200 ° C. from the viewpoint of securing the rolling temperature and cost. Is preferred.
Moreover, the temperature history of this hot rolling is an important factor with respect to the regulation of the manufacturing conditions of the clad steel sheet in the present invention. First, the hot rolling temperature, that is, the hot rolling finishing temperature is set to 900 ° C. or higher. Thereby, precipitation of the nitride at the time of hot rolling can be suppressed in the duplex stainless steel which is the laminated material of the present embodiment. Next, during cooling after hot rolling, the passing time in the range of 900 to 600 ° C. is set to 60 seconds or more and 15 minutes or less. This temperature range of 900 ° C. to 600 ° C. is the temperature range where the precipitation rate of nitride is the fastest. When passing through the temperature range for 15 minutes or more in the cooling process, the corrosion resistance decrease due to the precipitation and sensitization of nitrides at the time of the cooling becomes a level that cannot be ignored. On the other hand, in the case of rapid cooling with a passage time of less than 60 seconds, no precipitation occurred at that time, but it was found that precipitation was promoted by heat treatment at 700 ° C. for 3 minutes. In other words, if the transit time is very short to form a rapid cooling, the precipitation of nitrides can be prevented in the cooling stage after hot rolling, but linear heating (usually 1000%) performed when bending the clad steel plate is performed. Nitride may be precipitated by heating to about 0 ° C. It is presumed that this is because many dislocations generated during rolling remain due to rapid cooling after hot rolling, and these become precipitation nuclei during heat treatment at 700 ° C. for 3 minutes corresponding to linear heating.
That is, in the manufacturing method according to the present embodiment, during cooling after hot rolling, nitrides are most likely to precipitate (the precipitation rate is fast), and the passing time in the temperature range of 900 to 600 ° C. is within 60 seconds to 15 minutes. As a result, the precipitation of nitride during cooling can be suppressed, and the precipitation of nitride can also be suppressed when bending is performed by linear heating, which is a subsequent process.
In addition, since the corrosion resistance can be improved as the passage time is shorter than 60 seconds, it is preferably 5 minutes or less, more preferably 3 minutes or less.
また、この熱間圧延の温度履歴は本発明におけるクラッド鋼板の製造条件の規定に関して重要因子である。まず、熱間圧延温度、つまり熱間圧延の仕上げ温度は９００℃以上とする。これにより、本実施形態の合わせ材である二相ステンレス鋼において熱間圧延時における窒化物の析出を抑制することができる。次に、熱間圧延後の冷却時において、９００～６００℃の範囲の通過時間を６０秒以上１５分以内とする。この９００℃～６００℃の温度域は窒化物の析出速度が最も速い温度域である。冷却過程において当該温度域を１５分以上掛けて通過させた場合は当該冷却時に窒化物の析出、鋭敏化による耐食性低下が無視できないレベルになる。一方、通過時間が６０秒未満の急冷の場合は、その時点で析出は生じないが、７００℃×３分の熱処理によって析出が促進されることが判明した。つまり、通過時間を非常に短くして急冷の形態としてしまうと、熱間圧延後の冷却段階では窒化物の析出は防げるものの、クラッド鋼板に曲げ加工を施す際に行う線状加熱（通常、１０００℃程度まで加熱）によって窒化物が析出してしまうおそれがある。これは、熱間圧延後の急冷によって、圧延時に生じた転位が多く残存し、それが線状加熱に相当する７００℃×３分間の熱処理時に析出核となるためと推定される。
すなわち、本実施形態に係る製造方法では、熱間圧延後の冷却時において、窒化物が最も析出しやすい（析出速度が速い）９００～６００℃の温度域の通過時間を６０秒以上１５分以内とすることによって、冷却時の窒化物の析出を抑制するとともに、その後工程である線状加熱による曲げ加工を施す際においても窒化物の析出を抑制することができる。
なお、通過時間は６０秒以上ならば短いほど耐食性を改善出来るので、好ましくは５分以下、更に好ましくは３分以下とする。 Next, after carrying out a raw material heating process to this slab, it hot-rolls and a clad steel plate is manufactured. The material heating step is a step of reheating the slab in order to perform hot rolling, and the heating temperature is not particularly limited, but should be 1000 to 1200 ° C. from the viewpoint of securing the rolling temperature and cost. Is preferred.
Moreover, the temperature history of this hot rolling is an important factor with respect to the regulation of the manufacturing conditions of the clad steel sheet in the present invention. First, the hot rolling temperature, that is, the hot rolling finishing temperature is set to 900 ° C. or higher. Thereby, precipitation of the nitride at the time of hot rolling can be suppressed in the duplex stainless steel which is the laminated material of the present embodiment. Next, during cooling after hot rolling, the passing time in the range of 900 to 600 ° C. is set to 60 seconds or more and 15 minutes or less. This temperature range of 900 ° C. to 600 ° C. is the temperature range where the precipitation rate of nitride is the fastest. When passing through the temperature range for 15 minutes or more in the cooling process, the corrosion resistance decrease due to the precipitation and sensitization of nitrides at the time of the cooling becomes a level that cannot be ignored. On the other hand, in the case of rapid cooling with a passage time of less than 60 seconds, no precipitation occurred at that time, but it was found that precipitation was promoted by heat treatment at 700 ° C. for 3 minutes. In other words, if the transit time is very short to form a rapid cooling, the precipitation of nitrides can be prevented in the cooling stage after hot rolling, but linear heating (usually 1000%) performed when bending the clad steel plate is performed. Nitride may be precipitated by heating to about 0 ° C. It is presumed that this is because many dislocations generated during rolling remain due to rapid cooling after hot rolling, and these become precipitation nuclei during heat treatment at 700 ° C. for 3 minutes corresponding to linear heating.
That is, in the manufacturing method according to the present embodiment, during cooling after hot rolling, nitrides are most likely to precipitate (the precipitation rate is fast), and the passing time in the temperature range of 900 to 600 ° C. is within 60 seconds to 15 minutes. As a result, the precipitation of nitride during cooling can be suppressed, and the precipitation of nitride can also be suppressed when bending is performed by linear heating, which is a subsequent process.
In addition, since the corrosion resistance can be improved as the passage time is shorter than 60 seconds, it is preferably 5 minutes or less, more preferably 3 minutes or less.
以上のようにして本実施形態に係るクラッド鋼板を製造することができる。本実施形態に係る方法で得られるクラッド鋼板の合わせ材（二相ステンレス鋼）は、上記の通り、線状加熱時の析出物の生成を、鋼成分の制御、析出駆動力の制御、ならびに冷却段階での析出物の抑制によって防いでいる。このため、通常の熱間圧延鋼材に施される溶体化処理を省略することができる。この結果、製造コストの削減、製造時の使用エネルギーの低減を図ることができる。
As described above, the clad steel plate according to this embodiment can be manufactured. As described above, the clad steel sheet laminated material (duplex stainless steel) obtained by the method according to the present embodiment generates precipitates during linear heating, steel component control, precipitation driving force control, and cooling. This is prevented by suppressing precipitates at the stage. For this reason, the solution treatment applied to a normal hot rolled steel material can be omitted. As a result, it is possible to reduce manufacturing costs and energy used during manufacturing.
以下、実施例により本発明の効果を説明するが、本発明は、以下の実施例で用いた条件に限定されるものではない。
Hereinafter, the effects of the present invention will be described with reference to examples, but the present invention is not limited to the conditions used in the following examples.
表１に合わせ材の化学組成（質量％）を示す。
なお、表１に示した成分について含有量が記載されていない部分は意図的に添加していないこと、もしくはその含有量が不純物レベルであることを示している。また、ＲＥＭはランタノイド系希土類元素を意味し、含有量はそれら元素の合計を示している。また、Ｐ、Ｓ、Ｏは不可避的不純物であるが、本実施例においては表１に示す数値範囲となるよう制限した。 Table 1 shows the chemical composition (mass%) of the laminated material.
In addition, it has shown that the part which content is not described about the component shown in Table 1 is not added intentionally, or the content is an impurity level. REM means a lanthanoid rare earth element, and the content indicates the total of these elements. Further, P, S, and O are inevitable impurities, but in the present example, they were limited to the numerical range shown in Table 1.
なお、表１に示した成分について含有量が記載されていない部分は意図的に添加していないこと、もしくはその含有量が不純物レベルであることを示している。また、ＲＥＭはランタノイド系希土類元素を意味し、含有量はそれら元素の合計を示している。また、Ｐ、Ｓ、Ｏは不可避的不純物であるが、本実施例においては表１に示す数値範囲となるよう制限した。 Table 1 shows the chemical composition (mass%) of the laminated material.
In addition, it has shown that the part which content is not described about the component shown in Table 1 is not added intentionally, or the content is an impurity level. REM means a lanthanoid rare earth element, and the content indicates the total of these elements. Further, P, S, and O are inevitable impurities, but in the present example, they were limited to the numerical range shown in Table 1.
クラッド鋼板は、表１に示した化学組成の二相ステンレス鋼を合わせ材とし、Ｃ：０．１６％、Ｓｉ：０．２１％、Ｍｎ：０．６３％、Ｐ：０．０１８％、Ｓ：０．００６％、Ｎｉ：０．０１％、Ｃｒ：０．０４％、Ｃｕ：０．０２％、残部Ｆｅおよび不可避的不純物からなる組成を有するＳＳ４００鋼を母材として、所定の厚さの被圧延素材とした。被圧延素材は、母材と合わせ材とを溶接により組み立てて、前記合わせ材と母材とを合わせた組み立て後の総厚さを１３０ｍｍとしたスラブを形成した。このスラブを熱間圧延用の素材（被圧延素材）として用いた。
The clad steel plate is made of a duplex stainless steel having the chemical composition shown in Table 1, with C: 0.16%, Si: 0.21%, Mn: 0.63%, P: 0.018%, S : SS6 steel having a composition consisting of 0.006%, Ni: 0.01%, Cr: 0.04%, Cu: 0.02%, the balance Fe and unavoidable impurities, with a predetermined thickness A material to be rolled was used. As the material to be rolled, a base material and a mating material were assembled by welding to form a slab having a total thickness of 130 mm after assembling the mating material and the base material. This slab was used as a material for hot rolling (a material to be rolled).
熱間圧延は、被圧延素材のうち合わせ材側を下面として１１５０～１２２０℃の所定の温度に加熱した後、２段圧延機によりクラッド鋼板を作成した。熱間圧延条件としては、１０～１５回の圧下を繰り返し、被圧延素材の最終板厚が１０～３５ｍｍとなるように、表２に示すような熱延仕上げ温度８６５～９５６℃の範囲で仕上げ圧延を実施した。なお、最終パス直前の温度を熱延仕上げ温度とした。冷却床に移送して鋼板の表面温度を測定しつつ、表２に示す９００℃～６００℃までの経過時間となるよう制御しながら、放冷、又は種々の水流量にて水冷した。このようにして合わせ材の厚さが３ｍｍの圧延クラッド鋼板を得た。
次に、得られたクラッド鋼板Ｎｏ．１～１７、１９～２９それぞれにおいて、溶体化熱処理用のサンプル（溶体化熱処理材）を採取して、１０００℃×１０分で溶体化熱処理を実施した。
さらに、得られたクラッド鋼板（圧延まま）と、クラッド鋼板（圧延まま）を７００℃×３分熱処理したもの（７００℃×３分熱処理材、または単に７００℃熱処理材ともいう。）と、上記溶体化熱処理材とについてそれぞれから、合わせ材を取り出し、以下の評価を行った。 In the hot rolling, a clad steel plate was prepared by a two-stage rolling mill after heating to a predetermined temperature of 1150 to 1220 ° C. with the laminated material side of the material to be rolled as the lower surface. As hot rolling conditions, the rolling is repeated 10 to 15 times and finished in the range of 865 to 956 ° C as shown in Table 2 so that the final thickness of the material to be rolled is 10 to 35 mm. Rolling was performed. The temperature immediately before the final pass was defined as the hot rolling finishing temperature. While being transferred to a cooling bed and measuring the surface temperature of the steel sheet, it was allowed to cool or water-cooled at various water flow rates while controlling the elapsed time from 900 ° C. to 600 ° C. as shown in Table 2. In this way, a rolled clad steel sheet having a thickness of 3 mm was obtained.
Next, the obtained clad steel plate No. In each of 1 to 17 and 19 to 29, samples for solution heat treatment (solution heat treatment material) were collected, and solution heat treatment was performed at 1000 ° C. for 10 minutes.
Further, the obtained clad steel plate (as-rolled), the clad steel plate (as-rolled) heat-treated at 700 ° C. for 3 minutes (also referred to as 700 ° C. × 3-minute heat-treated material or simply 700 ° C. heat-treated material), and the above. The laminated material was taken out from each of the solution heat treatment materials and evaluated as follows.
次に、得られたクラッド鋼板Ｎｏ．１～１７、１９～２９それぞれにおいて、溶体化熱処理用のサンプル（溶体化熱処理材）を採取して、１０００℃×１０分で溶体化熱処理を実施した。
さらに、得られたクラッド鋼板（圧延まま）と、クラッド鋼板（圧延まま）を７００℃×３分熱処理したもの（７００℃×３分熱処理材、または単に７００℃熱処理材ともいう。）と、上記溶体化熱処理材とについてそれぞれから、合わせ材を取り出し、以下の評価を行った。 In the hot rolling, a clad steel plate was prepared by a two-stage rolling mill after heating to a predetermined temperature of 1150 to 1220 ° C. with the laminated material side of the material to be rolled as the lower surface. As hot rolling conditions, the rolling is repeated 10 to 15 times and finished in the range of 865 to 956 ° C as shown in Table 2 so that the final thickness of the material to be rolled is 10 to 35 mm. Rolling was performed. The temperature immediately before the final pass was defined as the hot rolling finishing temperature. While being transferred to a cooling bed and measuring the surface temperature of the steel sheet, it was allowed to cool or water-cooled at various water flow rates while controlling the elapsed time from 900 ° C. to 600 ° C. as shown in Table 2. In this way, a rolled clad steel sheet having a thickness of 3 mm was obtained.
Next, the obtained clad steel plate No. In each of 1 to 17 and 19 to 29, samples for solution heat treatment (solution heat treatment material) were collected, and solution heat treatment was performed at 1000 ° C. for 10 minutes.
Further, the obtained clad steel plate (as-rolled), the clad steel plate (as-rolled) heat-treated at 700 ° C. for 3 minutes (also referred to as 700 ° C. × 3-minute heat-treated material or simply 700 ° C. heat-treated material), and the above. The laminated material was taken out from each of the solution heat treatment materials and evaluated as follows.
孔食電位は、クラッド鋼板（圧延まま）、クラッド鋼板（圧延まま）を７００℃×３分熱処理したもの、及び上記溶体化熱処理材について、それぞれの鋼材の表皮下１ｍｍの面に対してＪＩＳ Ｇ０５７７：２００５に定められた方法にて電流密度１００μＡ／ｃｍ２に対応する電位（ＶＣ’１００）を測定した。そして、溶体化熱処理を施す前後（つまり、圧延まま材と溶体化熱処理材）および７００℃熱処理後の鋼材についてそれぞれサンプル数ｎ＝４で測定し、平均値を求めた。その後、圧延まま材及び７００℃熱処理材それぞれと溶体化熱処理材（表２中では溶体化材と表記）との平均値の差を求めた。なお、溶体化熱処理を行うことで、熱間圧延やその後の冷却工程において析出したＣｒ炭窒化物等の析出物を固溶させることができ、優れた耐食性を確保できる。つまり、溶体化熱処理材との孔食電位の差が小さければ、その鋼材（圧延まま材、７００℃熱処理材）は優れた耐食性を維持できている、つまりＣｒ炭窒化物等の析出を抑制できたと評価できる。
従って、本実施例では、圧延まま材と溶体化熱処理材との孔食電位の差が０．１０Ｖ未満であれば、圧延まま材そのものの耐食性の低下を抑制できたものとして評価することとした。そして圧延まま材そのものの耐食性劣化を抑制できていたとしても、その後の線状加熱処理（前記７００℃×３分熱処理）によって耐食性が変動するおそれがある。このことから、圧延まま材のうち孔食電位の低下が小さかったものも含めて７００℃×３分熱処理後の孔食電位を測定し、溶体化熱処理材との差を求め、その差が０．１０Ｖ未満であれば、線状加熱処理（前記７００℃×３分熱処理）においても耐食性の劣化を抑制できたものとして評価することとした。また、上記の差が０．０５Ｖ以下であれば、特に耐食性の劣化抑制効果が高いものとして評価した。
抽出残渣分析は前述の方法で析出物中のクロム量を求めた。
オーステナイト相の面積率については、圧延方向と平行な断面を埋込み鏡面研磨し、ＫＯＨ水溶液中で電解エッチングを行った後、光学顕微鏡観察により画像解析を行うことによってフェライト相面積率を測定し、残りの部分をオーステナイト相面積率とした。フェライト相面積率は、圧延方向と平行な断面を埋込み鏡面研磨し、ＫＯＨ水溶液中で電解エッチングを行った後、光学顕微鏡観察により画像解析を行うことによって測定した。観察倍率は４００倍、観察面積は3.75mm2とした。フェライト相面積の測定は、ＡＳＴＭ Ｅ１２４５－０３「Standard Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis」に準拠した方法で行った。
母材の衝撃特性（靱性）については、ＪＩＳ Ｚ ２２４２：２００５（ＩＳＯ／ＤＩＳ １４９－１：２００３に対応）に規定される４号Ｖノッチシャルピー試験片を圧延直角方向より各３本切り出し、破壊が圧延方向に伝播するようにＶノッチを加工して、最大エネルギー５００Ｊ仕様の試験機にて－２０℃での衝撃値を測定した。衝撃値が１５０Ｊ／ｃｍ２以下であれば、靱性が実用に要する基準を満たさない（靱性不良）と評価した。 The pitting potential was measured according to JIS G0577 with respect to the surface of 1 mm of the subepidermal surface of the clad steel plate (as-rolled), clad steel plate (as-rolled) heat-treated at 700 ° C. for 3 minutes, and the solution heat-treated material. : A potential (VC′100) corresponding to a current density of 100 μA / cm 2 was measured by the method defined in 2005. Then, before and after the solution heat treatment (that is, as-rolled material and solution heat treated material) and the steel material after 700 ° C. heat treatment were measured with the number of samples n = 4, and the average value was obtained. Thereafter, the difference between the average values of the as-rolled material and the 700 ° C. heat treated material and the solution heat treated material (denoted as the solution treated material in Table 2) was determined. In addition, by performing solution heat treatment, precipitates such as Cr carbonitride precipitated in hot rolling and the subsequent cooling step can be dissolved, and excellent corrosion resistance can be secured. In other words, if the difference in pitting potential with the solution heat treated material is small, the steel material (as-rolled material, 700 ° C. heat treated material) can maintain excellent corrosion resistance, that is, it can suppress the precipitation of Cr carbonitride and the like. Can be evaluated.
Therefore, in this example, if the difference in pitting potential between the as-rolled material and the solution heat-treated material is less than 0.10 V, it was evaluated that the reduction in the corrosion resistance of the as-rolled material itself could be suppressed. . And even if the corrosion resistance deterioration of the material itself can be suppressed as it is rolled, there is a possibility that the corrosion resistance may vary due to the subsequent linear heat treatment (the heat treatment at 700 ° C. for 3 minutes). From this, the pitting corrosion potential after heat treatment at 700 ° C. for 3 minutes including those with as-rolled materials having a small decrease in pitting potential was measured, and the difference from the solution heat treated material was determined. If it is less than 10 V, it was determined that the deterioration of the corrosion resistance could be suppressed even in the linear heat treatment (the heat treatment at 700 ° C. for 3 minutes). Moreover, if said difference was 0.05 V or less, it evaluated as a thing with especially high corrosion-resistant deterioration inhibitory effect.
Extraction residue analysis determined the amount of chromium in the precipitate by the method described above.
Regarding the area ratio of the austenite phase, the cross section parallel to the rolling direction is embedded and mirror-polished, and after electrolytic etching in an aqueous KOH solution, the ferrite phase area ratio is measured by performing image analysis with an optical microscope, and the rest This portion was defined as the austenite phase area ratio. The ferrite phase area ratio was measured by embedding a cross section parallel to the rolling direction, mirror polishing, performing electrolytic etching in a KOH aqueous solution, and then performing image analysis by observation with an optical microscope. The observation magnification was 400 times and the observation area was 3.75 mm 2 . The ferrite phase area was measured by a method based on ASTM E1245-03 “Standard Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis”.
For the impact properties (toughness) of the base metal, three No. 4 V-notch Charpy test pieces defined in JIS Z 2242: 2005 (corresponding to ISO / DIS 149-1: 2003) were cut out from each direction perpendicular to the rolling direction and fractured. V notch was processed so as to propagate in the rolling direction, and the impact value at −20 ° C. was measured with a tester with a maximum energy of 500 J specifications. When the impact value was 150 J / cm 2 or less, it was evaluated that the toughness did not satisfy the standard required for practical use (poor toughness).
従って、本実施例では、圧延まま材と溶体化熱処理材との孔食電位の差が０．１０Ｖ未満であれば、圧延まま材そのものの耐食性の低下を抑制できたものとして評価することとした。そして圧延まま材そのものの耐食性劣化を抑制できていたとしても、その後の線状加熱処理（前記７００℃×３分熱処理）によって耐食性が変動するおそれがある。このことから、圧延まま材のうち孔食電位の低下が小さかったものも含めて７００℃×３分熱処理後の孔食電位を測定し、溶体化熱処理材との差を求め、その差が０．１０Ｖ未満であれば、線状加熱処理（前記７００℃×３分熱処理）においても耐食性の劣化を抑制できたものとして評価することとした。また、上記の差が０．０５Ｖ以下であれば、特に耐食性の劣化抑制効果が高いものとして評価した。
抽出残渣分析は前述の方法で析出物中のクロム量を求めた。
オーステナイト相の面積率については、圧延方向と平行な断面を埋込み鏡面研磨し、ＫＯＨ水溶液中で電解エッチングを行った後、光学顕微鏡観察により画像解析を行うことによってフェライト相面積率を測定し、残りの部分をオーステナイト相面積率とした。フェライト相面積率は、圧延方向と平行な断面を埋込み鏡面研磨し、ＫＯＨ水溶液中で電解エッチングを行った後、光学顕微鏡観察により画像解析を行うことによって測定した。観察倍率は４００倍、観察面積は3.75mm2とした。フェライト相面積の測定は、ＡＳＴＭ Ｅ１２４５－０３「Standard Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis」に準拠した方法で行った。
母材の衝撃特性（靱性）については、ＪＩＳ Ｚ ２２４２：２００５（ＩＳＯ／ＤＩＳ １４９－１：２００３に対応）に規定される４号Ｖノッチシャルピー試験片を圧延直角方向より各３本切り出し、破壊が圧延方向に伝播するようにＶノッチを加工して、最大エネルギー５００Ｊ仕様の試験機にて－２０℃での衝撃値を測定した。衝撃値が１５０Ｊ／ｃｍ２以下であれば、靱性が実用に要する基準を満たさない（靱性不良）と評価した。 The pitting potential was measured according to JIS G0577 with respect to the surface of 1 mm of the subepidermal surface of the clad steel plate (as-rolled), clad steel plate (as-rolled) heat-treated at 700 ° C. for 3 minutes, and the solution heat-treated material. : A potential (VC′100) corresponding to a current density of 100 μA / cm 2 was measured by the method defined in 2005. Then, before and after the solution heat treatment (that is, as-rolled material and solution heat treated material) and the steel material after 700 ° C. heat treatment were measured with the number of samples n = 4, and the average value was obtained. Thereafter, the difference between the average values of the as-rolled material and the 700 ° C. heat treated material and the solution heat treated material (denoted as the solution treated material in Table 2) was determined. In addition, by performing solution heat treatment, precipitates such as Cr carbonitride precipitated in hot rolling and the subsequent cooling step can be dissolved, and excellent corrosion resistance can be secured. In other words, if the difference in pitting potential with the solution heat treated material is small, the steel material (as-rolled material, 700 ° C. heat treated material) can maintain excellent corrosion resistance, that is, it can suppress the precipitation of Cr carbonitride and the like. Can be evaluated.
Therefore, in this example, if the difference in pitting potential between the as-rolled material and the solution heat-treated material is less than 0.10 V, it was evaluated that the reduction in the corrosion resistance of the as-rolled material itself could be suppressed. . And even if the corrosion resistance deterioration of the material itself can be suppressed as it is rolled, there is a possibility that the corrosion resistance may vary due to the subsequent linear heat treatment (the heat treatment at 700 ° C. for 3 minutes). From this, the pitting corrosion potential after heat treatment at 700 ° C. for 3 minutes including those with as-rolled materials having a small decrease in pitting potential was measured, and the difference from the solution heat treated material was determined. If it is less than 10 V, it was determined that the deterioration of the corrosion resistance could be suppressed even in the linear heat treatment (the heat treatment at 700 ° C. for 3 minutes). Moreover, if said difference was 0.05 V or less, it evaluated as a thing with especially high corrosion-resistant deterioration inhibitory effect.
Extraction residue analysis determined the amount of chromium in the precipitate by the method described above.
Regarding the area ratio of the austenite phase, the cross section parallel to the rolling direction is embedded and mirror-polished, and after electrolytic etching in an aqueous KOH solution, the ferrite phase area ratio is measured by performing image analysis with an optical microscope, and the rest This portion was defined as the austenite phase area ratio. The ferrite phase area ratio was measured by embedding a cross section parallel to the rolling direction, mirror polishing, performing electrolytic etching in a KOH aqueous solution, and then performing image analysis by observation with an optical microscope. The observation magnification was 400 times and the observation area was 3.75 mm 2 . The ferrite phase area was measured by a method based on ASTM E1245-03 “Standard Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic Image Analysis”.
For the impact properties (toughness) of the base metal, three No. 4 V-notch Charpy test pieces defined in JIS Z 2242: 2005 (corresponding to ISO / DIS 149-1: 2003) were cut out from each direction perpendicular to the rolling direction and fractured. V notch was processed so as to propagate in the rolling direction, and the impact value at −20 ° C. was measured with a tester with a maximum energy of 500 J specifications. When the impact value was 150 J / cm 2 or less, it was evaluated that the toughness did not satisfy the standard required for practical use (poor toughness).
Ｎｏ．１～１１、１５、２７～２９は本発明例の結果である。本発明例の結果では、７００℃熱処理材において析出物中のクロム量が何れも０．０５％以下にとどまっている。また、圧延まま材の孔食電位差については、溶体化熱処理材（溶体化材）と比べ０．１０Ｖ未満の低下量にとどまっていた。これにより、熱間圧延後の冷却過程におけるＣｒ炭窒化物の析出を抑制できていることが分かる。また、７００℃熱処理材の結果から明らかなように、本発明例であるクラッド鋼板は、線状加熱を施しても耐食性の劣化が少ないことが明らかである。また、９００～６００℃までの経過時間が３ｍｉｎ以下であるＮｏ．１、４、６、８～１１、２８、２９は、線状加熱時における溶体化材との孔食電位差（７００℃熱処理材と溶体化剤との孔食電位差）が０．０５Ｖ以下となっており、特に耐食性の劣化抑制効果が高いことが分かる。一方、９００～６００℃までの経過時間が３ｍｉｎを超えるＮｏ．２、Ｎｏ．２７、Ｎｏ．１５とＮｏ．３０をそれぞれ比較すると、線状加熱時における耐食性の劣化抑制効果（７００℃熱処理材と溶体化剤との孔食電位差）が０．０５Ｖ以下のこともあれば、０．０５Ｖ超のこともあることが分かる。以上のことから、９００～６００℃までの経過時間が３ｍｉｎ以下である場合、線状加熱時における耐食性の劣化抑制効果が安定して良好になることが判明した。
No. 1 to 11, 15 and 27 to 29 are the results of the examples of the present invention. As a result of the example of the present invention, in the heat treated material at 700 ° C., the amount of chromium in the precipitates remains at 0.05% or less. Further, the pitting corrosion potential difference of the as-rolled material was only reduced by less than 0.10 V compared to the solution heat-treated material (solution-treated material). Thereby, it turns out that precipitation of Cr carbonitride in the cooling process after hot rolling can be suppressed. Further, as is apparent from the results of the heat treated material at 700 ° C., it is clear that the clad steel plate as an example of the present invention has little deterioration in corrosion resistance even when subjected to linear heating. Further, No. No. whose elapsed time from 900 to 600 ° C. is 3 min or less. Nos. 1, 4, 6, 8 to 11, 28, 29 have a pitting corrosion potential difference with the solution material during linear heating (pitting corrosion potential difference between the 700 ° C. heat treatment material and the solution agent) of 0.05 V or less. It can be seen that the effect of suppressing deterioration of corrosion resistance is particularly high. On the other hand, the elapsed time from 900 to 600 ° C. exceeds 3 min. 2, No. 27, no. 15 and No. When comparing 30 with each other, the effect of suppressing deterioration of corrosion resistance during linear heating (pitting corrosion potential difference between the heat-treated material at 700 ° C. and the solution agent) may be 0.05 V or less, or may be more than 0.05 V. I understand that. From the above, it has been found that when the elapsed time from 900 to 600 ° C. is 3 min or less, the effect of inhibiting the deterioration of corrosion resistance during linear heating becomes stable and good.
一方、Ｎｏ．１２～１４、１６、１７、１９～２１は、成分が本発明範囲外もしくはＮｐｒｅ値の高い鋼を使用した比較例である。
Ｎｏ．１２はＣが高いためＣｒ炭化物が生成してしまい、熱延まま材の耐食性が大きく低下した。
Ｎｏ．１３はＳｉが高いため、Ｎｏ．１６はＮｉが低いため、靭性が低下した。
Ｎｏ．１４はＮｐｒｅの上限を満たすことが出来ず、また、Ｎｏ．２０は同様にＮｐｒｅが９２０℃を上回ったため、７００℃×３分の加熱にて析出物中のクロム量が何れも０．０５％を超え耐食性が大幅に低下した。
Ｎｏ．１９はＶが低いため、Ｎｐｒｅは９２０℃を下回っているものの、析出物中のクロム量が０．０５％を超え耐食性低下が見られた。
Ｎｏ．１７はＣｒが低いため、Ｎｐｒｅは９２０℃を下回っており、析出物中のクロム量が０．０５％以下にとどまっているものの耐食性低下が見られた。
Ｎｏ．２１はオーステナイト量が少なく、その結果Ｎｐｒｅは９２０℃を下回っているものの、析出物中のクロム量が０．０５％を超え耐食性低下が見られた。 On the other hand, no. Nos. 12 to 14, 16, 17, and 19 to 21 are comparative examples using steels having components outside the range of the present invention or having a high Npre value.
No. In No. 12, since C was high, Cr carbide was generated, and the corrosion resistance of the material was greatly reduced as it was hot rolled.
No. No. 13 is high in Si. Since No. 16 had low Ni, toughness fell.
No. No. 14 cannot satisfy the upper limit of Npre. Similarly, since Npre was higher than 920 ° C., the amount of chromium in the precipitate exceeded 0.05% by heating at 700 ° C. for 3 minutes, and the corrosion resistance was greatly reduced.
No. No. 19 had a low V, so Npre was below 920 ° C., but the chromium content in the precipitate exceeded 0.05%, and a decrease in corrosion resistance was observed.
No. Since No. 17 had a low Cr, Npre was below 920 ° C., and although the amount of chromium in the precipitate remained at 0.05% or less, a decrease in corrosion resistance was observed.
No. No. 21 had a small amount of austenite and, as a result, Npre was lower than 920 ° C., but the chromium content in the precipitate exceeded 0.05%, and a decrease in corrosion resistance was observed.
Ｎｏ．１２はＣが高いためＣｒ炭化物が生成してしまい、熱延まま材の耐食性が大きく低下した。
Ｎｏ．１３はＳｉが高いため、Ｎｏ．１６はＮｉが低いため、靭性が低下した。
Ｎｏ．１４はＮｐｒｅの上限を満たすことが出来ず、また、Ｎｏ．２０は同様にＮｐｒｅが９２０℃を上回ったため、７００℃×３分の加熱にて析出物中のクロム量が何れも０．０５％を超え耐食性が大幅に低下した。
Ｎｏ．１９はＶが低いため、Ｎｐｒｅは９２０℃を下回っているものの、析出物中のクロム量が０．０５％を超え耐食性低下が見られた。
Ｎｏ．１７はＣｒが低いため、Ｎｐｒｅは９２０℃を下回っており、析出物中のクロム量が０．０５％以下にとどまっているものの耐食性低下が見られた。
Ｎｏ．２１はオーステナイト量が少なく、その結果Ｎｐｒｅは９２０℃を下回っているものの、析出物中のクロム量が０．０５％を超え耐食性低下が見られた。 On the other hand, no. Nos. 12 to 14, 16, 17, and 19 to 21 are comparative examples using steels having components outside the range of the present invention or having a high Npre value.
No. In No. 12, since C was high, Cr carbide was generated, and the corrosion resistance of the material was greatly reduced as it was hot rolled.
No. No. 13 is high in Si. Since No. 16 had low Ni, toughness fell.
No. No. 14 cannot satisfy the upper limit of Npre. Similarly, since Npre was higher than 920 ° C., the amount of chromium in the precipitate exceeded 0.05% by heating at 700 ° C. for 3 minutes, and the corrosion resistance was greatly reduced.
No. No. 19 had a low V, so Npre was below 920 ° C., but the chromium content in the precipitate exceeded 0.05%, and a decrease in corrosion resistance was observed.
No. Since No. 17 had a low Cr, Npre was below 920 ° C., and although the amount of chromium in the precipitate remained at 0.05% or less, a decrease in corrosion resistance was observed.
No. No. 21 had a small amount of austenite and, as a result, Npre was lower than 920 ° C., but the chromium content in the precipitate exceeded 0.05%, and a decrease in corrosion resistance was observed.
更に、Ｎｏ．２２～２６は、本発明範囲外の製造方法による比較例である。
番号Ｎｏ．２２，２５は急冷過ぎる（９００～６００℃までの経過時間が短過ぎる）ため、７００℃×３分熱処理で析出が多く生じ耐食性が低下した。
番号Ｎｏ．２３，２４、２６は圧延温度が低すぎもしくは徐冷過ぎる（９００～６００℃までの経過時間が長過ぎる）ため、圧延まま材で窒化物の析出が多く耐食性が低下した。 Furthermore, no. 22 to 26 are comparative examples produced by the production method outside the scope of the present invention.
No. Since Nos. 22 and 25 were too rapidly cooled (the elapsed time from 900 to 600 ° C. was too short), a large amount of precipitation was caused by heat treatment at 700 ° C. for 3 minutes, and the corrosion resistance was lowered.
No. In Nos. 23, 24, and 26, the rolling temperature was too low or gradually cooled (the elapsed time from 900 to 600 ° C. was too long), and as a result, the nitride was precipitated in the as-rolled material and the corrosion resistance was lowered.
番号Ｎｏ．２２，２５は急冷過ぎる（９００～６００℃までの経過時間が短過ぎる）ため、７００℃×３分熱処理で析出が多く生じ耐食性が低下した。
番号Ｎｏ．２３，２４、２６は圧延温度が低すぎもしくは徐冷過ぎる（９００～６００℃までの経過時間が長過ぎる）ため、圧延まま材で窒化物の析出が多く耐食性が低下した。 Furthermore, no. 22 to 26 are comparative examples produced by the production method outside the scope of the present invention.
No. Since Nos. 22 and 25 were too rapidly cooled (the elapsed time from 900 to 600 ° C. was too short), a large amount of precipitation was caused by heat treatment at 700 ° C. for 3 minutes, and the corrosion resistance was lowered.
No. In Nos. 23, 24, and 26, the rolling temperature was too low or gradually cooled (the elapsed time from 900 to 600 ° C. was too long), and as a result, the nitride was precipitated in the as-rolled material and the corrosion resistance was lowered.
以上の実施例からわかるように本発明により省合金タイプ二相ステンレス鋼を合わせ材とし、溶体化熱処理を省略しても線状加熱性が良好な安価なクラッド鋼板が得られることが明確となった。
As can be seen from the above examples, the present invention makes it possible to obtain an inexpensive clad steel sheet having good linear heatability even when the alloy heat treatment type duplex stainless steel is used as a combined material and the solution heat treatment is omitted. It was.
本発明のクラッド鋼板およびその製造方法によれば、線状加熱時の耐食性低下を抑制することができると共に、安価で少ないエネルギーでクラッド鋼板を製造できる。このため、本発明によれば、ケミカルタンカーをはじめとする輸送用のタンク等に好適なクラッド鋼板およびその製造方法を提供できる。
According to the clad steel plate and the method for producing the same according to the present invention, it is possible to suppress a decrease in corrosion resistance during linear heating, and it is possible to produce a clad steel plate with low cost and little energy. Therefore, according to the present invention, it is possible to provide a clad steel plate suitable for a transport tank including a chemical tanker and a method for producing the same.
Claims (6)
- 二相ステンレス鋼を合わせ材、炭素鋼もしくは合金鋼を母材とするクラッド鋼板であって、該二相ステンレス鋼が、
質量％にて、Ｃ：０．０３％以下、Ｓｉ：０．１～１．０％、Ｍｎ：１．０～７．０％、Ｐ：０．０５％以下、Ｓ：０．００５％以下、Ｃｒ：２０．５～２４．０％、Ｎｉ：１．５～５．０％、Ｖ：０．０５～０．５％、Ａｌ：０．００３～０．０５０％、Ｏ：０．００７％以下、Ｎ：０．１０～０．２５％を含有し、さらに、Ｍｏ：１．０％以下及び／またはＣｕ：２．０％以下を含有し、残部がＦｅおよび不可避的不純物からなり、オーステナイト相面積率が４０～７０％であり、（１）式で示されるＣｒ窒化物の析出開始温度計算値Ｎpreが９２０℃以下であり、
７００℃で３分間等温熱処理した後、前記クラッド鋼板から前記合わせ材のみを切り出し電解抽出残渣分析を行って求めた析出物中のクロム量が０．０５％以下であることを特徴とする、線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板。
Ｎｐｒｅ＝１２Ｃｒ＋５０Ｓｉ＋３６Ｍｏ－２０Ｎｉ－１５Ｍｎ
＋２８Ｃｕ＋４７０Ｎ－２９０Ｃ＋６２０・・・・・・（１）
上記の式において各元素名は何れもその含有量（質量％）を表す。また、上記の式において鋼中に含有されない元素については、０を代入することとする。 A clad steel plate having a duplex stainless steel as a base material, carbon steel or alloy steel as a base material, wherein the duplex stainless steel is
In mass%, C: 0.03% or less, Si: 0.1 to 1.0%, Mn: 1.0 to 7.0%, P: 0.05% or less, S: 0.005% or less Cr: 20.5 to 24.0%, Ni: 1.5 to 5.0%, V: 0.05 to 0.5%, Al: 0.003 to 0.050%, O: 0.007 %: N: 0.10 to 0.25%, Mo: 1.0% or less and / or Cu: 2.0% or less, the balance consisting of Fe and inevitable impurities, The area ratio of the austenite phase is 40 to 70%, and the calculated precipitation start temperature Npre of Cr nitride represented by the formula (1) is 920 ° C. or less,
After the isothermal heat treatment at 700 ° C. for 3 minutes, the amount of chromium in the precipitate obtained by cutting out only the laminated material from the clad steel plate and conducting an electrolytic extraction residue analysis is 0.05% or less, Clad steel plate made of duplex stainless steel with good linear heatability.
Npre = 12Cr + 50Si + 36Mo-20Ni-15Mn
+ 28Cu + 470N-290C + 620 (1)
In the above formula, each element name represents its content (% by mass). In the above formula, 0 is substituted for elements not contained in the steel. - 請求項１に記載の二相ステンレス鋼において、Ｎｂを０．０２～０．１５％かつＮｂ×Ｎが０．００３～０．０１５（ここで、Ｎｂ、Ｎは夫々の含有量の質量％を表す）となるように含有することを特徴とする線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板。 2. The duplex stainless steel according to claim 1, wherein Nb is 0.02 to 0.15% and Nb × N is 0.003 to 0.015 (where Nb and N are the mass% of the respective contents). A clad steel sheet comprising a duplex stainless steel with good linear heatability, characterized in that it is contained so that
- 請求項１または２に記載の二相ステンレス鋼において、
Ｃａ：０．００５０％以下、
Ｍｇ：０．００５０％以下、
ＲＥＭ：０．０５０％以下、
Ｂ：０．００４０％以下の１種または２種以上を含有することを特徴とする線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板。 In the duplex stainless steel according to claim 1 or 2,
Ca: 0.0050% or less,
Mg: 0.0050% or less,
REM: 0.050% or less,
B: A clad steel sheet comprising a duplex stainless steel with good linear heatability, characterized by containing one or more of 0.0040% or less. - 請求項１ないし３のいずれか一項に記載の二相ステンレス鋼において、Ｃｏを０．０２～１．００％含有することを特徴とする線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板。 The duplex stainless steel according to any one of claims 1 to 3, wherein 0.02 to 1.00% of Co is contained, and the duplex stainless steel with good linear heatability is combined with the laminated material. Clad steel sheet.
- 請求項１ないし４のいずれか一項に記載の二相ステンレス鋼において、更に質量％にて
Ｔｉ：０．０５％以下、
Ｗ：１．０％以下、
Ｓｎ：０．１％以下の１種または２種以上を含有することを特徴とする線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板。 In the duplex stainless steel according to any one of claims 1 to 4, further in mass%, Ti: 0.05% or less,
W: 1.0% or less,
Sn: A clad steel plate comprising a duplex stainless steel with good linear heatability, characterized by containing one or more of 0.1% or less. - 請求項１～５のいずれか一項に記載の二相ステンレス鋼を合わせ材とし、前記合わせ材と、普通鋼もしくは合金鋼からなる母材とを組み合わせた被圧延素材を、９００℃以上で熱間圧延し、その後の冷却時において９００～６００℃までの通過時間を６０秒以上１５分以内とし、前記冷却後はそのまま熱処理せずにクラッド鋼板とすることを特徴とする線状加熱性良好な二相ステンレス鋼を合わせ材とするクラッド鋼板の製造方法。 A material to be rolled comprising the duplex stainless steel according to any one of claims 1 to 5 as a laminated material, and a combination of the laminated material and a base material made of ordinary steel or alloy steel is heated at 900 ° C or higher. It has good linear heating characteristics, characterized in that it is cold-rolled and the passage time from 900 ° C. to 600 ° C. during the subsequent cooling is 60 seconds or more and 15 minutes or less, and the clad steel sheet is not subjected to heat treatment after the cooling. A method for producing a clad steel plate made of duplex stainless steel.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2018181990A1 (en) * | 2017-03-30 | 2018-10-04 | 新日鐵住金ステンレス株式会社 | Two-phase stainless steel and manufacturing method therefor |
| CN109778181A (en) * | 2019-03-08 | 2019-05-21 | 中国长江电力股份有限公司 | Substitute the material and construction technology of the operating oil line chromium plating of power station oil head |
| JP2019157218A (en) * | 2018-03-14 | 2019-09-19 | 日鉄ステンレス株式会社 | Ferritic/austenitic duplex stainless steel sheet for automobile fastening component |
| WO2020108317A1 (en) * | 2018-11-29 | 2020-06-04 | 宝山钢铁股份有限公司 | Super duplex stainless steel clad steel plate and manufacturing method therefor |
| WO2020203938A1 (en) * | 2019-03-29 | 2020-10-08 | 日鉄ステンレス株式会社 | Cladded steel plate and method for manufacturing same |
| CN111902559A (en) * | 2018-03-30 | 2020-11-06 | 杰富意钢铁株式会社 | Duplex stainless steel clad steel sheet and method for manufacturing same |
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| CN112002457A (en) * | 2020-08-20 | 2020-11-27 | 湖南科技学院 | High-conductivity copper-clad rare earth aluminum alloy clad wire and preparation process thereof |
| WO2021021010A1 (en) * | 2019-07-31 | 2021-02-04 | Ferritico Ab | Duplex stainless steel with improved embrittlement properties and method of producing such |
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| EP3778960A4 (en) * | 2018-03-30 | 2021-09-08 | NIPPON STEEL Stainless Steel Corporation | Two-phase stainless-clad steel sheet and production method thereof |
| WO2023138595A1 (en) * | 2022-01-21 | 2023-07-27 | 宝山钢铁股份有限公司 | High-strength pipeline resistant to sodium hydroxide corrosion and manufacturing method therefor |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012102330A1 (en) * | 2011-01-27 | 2012-08-02 | 新日鐵住金ステンレス株式会社 | Alloying element-saving hot rolled duplex stainless steel material, clad steel sheet having duplex stainless steel as mating material therefor, and production method for same |
-
2014
- 2014-03-19 WO PCT/JP2014/057501 patent/WO2014148540A1/en active Application Filing
- 2014-03-19 JP JP2015506825A patent/JP6149102B2/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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