WO2014112445A1 - 二相ステンレス鋼材および二相ステンレス鋼管 - Google Patents
二相ステンレス鋼材および二相ステンレス鋼管 Download PDFInfo
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- WO2014112445A1 WO2014112445A1 PCT/JP2014/050363 JP2014050363W WO2014112445A1 WO 2014112445 A1 WO2014112445 A1 WO 2014112445A1 JP 2014050363 W JP2014050363 W JP 2014050363W WO 2014112445 A1 WO2014112445 A1 WO 2014112445A1
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- 239000000463 material Substances 0.000 title claims abstract description 106
- 229910001039 duplex stainless steel Inorganic materials 0.000 title claims abstract description 83
- 229910001566 austenite Inorganic materials 0.000 claims abstract description 27
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 26
- 239000000203 mixture Substances 0.000 claims abstract description 24
- 239000012535 impurity Substances 0.000 claims abstract description 14
- 229910052717 sulfur Inorganic materials 0.000 claims description 32
- 238000012545 processing Methods 0.000 claims description 30
- 239000002131 composite material Substances 0.000 claims description 28
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 23
- 239000011593 sulfur Substances 0.000 claims description 23
- 238000005260 corrosion Methods 0.000 description 141
- 230000007797 corrosion Effects 0.000 description 141
- 229910000831 Steel Inorganic materials 0.000 description 90
- 239000010959 steel Substances 0.000 description 90
- 239000000523 sample Substances 0.000 description 30
- 238000000034 method Methods 0.000 description 25
- 230000000694 effects Effects 0.000 description 24
- 229910001220 stainless steel Inorganic materials 0.000 description 17
- 229910052804 chromium Inorganic materials 0.000 description 16
- 238000004519 manufacturing process Methods 0.000 description 16
- 239000010935 stainless steel Substances 0.000 description 15
- 229910052750 molybdenum Inorganic materials 0.000 description 14
- 229910052757 nitrogen Inorganic materials 0.000 description 14
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 12
- 238000012360 testing method Methods 0.000 description 12
- 229910052791 calcium Inorganic materials 0.000 description 11
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 10
- 230000007547 defect Effects 0.000 description 10
- 230000001965 increasing effect Effects 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 8
- 238000005242 forging Methods 0.000 description 8
- 229910052758 niobium Inorganic materials 0.000 description 8
- 150000004767 nitrides Chemical class 0.000 description 8
- 239000003129 oil well Substances 0.000 description 8
- 238000001556 precipitation Methods 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 239000013535 sea water Substances 0.000 description 8
- 229910052719 titanium Inorganic materials 0.000 description 8
- 230000015572 biosynthetic process Effects 0.000 description 7
- 239000003518 caustics Substances 0.000 description 7
- 238000011156 evaluation Methods 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 7
- 238000005259 measurement Methods 0.000 description 7
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 6
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 6
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 6
- 229910002092 carbon dioxide Inorganic materials 0.000 description 6
- 239000001569 carbon dioxide Substances 0.000 description 6
- 229910052802 copper Inorganic materials 0.000 description 6
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 6
- 230000006872 improvement Effects 0.000 description 6
- 238000002844 melting Methods 0.000 description 6
- 230000008018 melting Effects 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- 229910052710 silicon Inorganic materials 0.000 description 6
- 230000000087 stabilizing effect Effects 0.000 description 6
- 229910052720 vanadium Inorganic materials 0.000 description 6
- 230000002411 adverse Effects 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 5
- 229910052748 manganese Inorganic materials 0.000 description 5
- 229910052759 nickel Inorganic materials 0.000 description 5
- FAPWRFPIFSIZLT-UHFFFAOYSA-M sodium chloride Inorganic materials [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 229910052721 tungsten Inorganic materials 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 238000010612 desalination reaction Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 229910052715 tantalum Inorganic materials 0.000 description 4
- 230000002378 acidificating effect Effects 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 238000005266 casting Methods 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- TXKMVPPZCYKFAC-UHFFFAOYSA-N disulfur monoxide Inorganic materials O=S=S TXKMVPPZCYKFAC-UHFFFAOYSA-N 0.000 description 3
- 229910000765 intermetallic Inorganic materials 0.000 description 3
- 150000001247 metal acetylides Chemical class 0.000 description 3
- 229910052698 phosphorus Inorganic materials 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 230000002829 reductive effect Effects 0.000 description 3
- 238000007670 refining Methods 0.000 description 3
- 239000011780 sodium chloride Substances 0.000 description 3
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical compound S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 238000009749 continuous casting Methods 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 230000002950 deficient Effects 0.000 description 2
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical class Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 2
- 238000004453 electron probe microanalysis Methods 0.000 description 2
- 230000002708 enhancing effect Effects 0.000 description 2
- 239000003822 epoxy resin Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 235000006408 oxalic acid Nutrition 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 238000002161 passivation Methods 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 239000002893 slag Substances 0.000 description 2
- 230000006641 stabilisation Effects 0.000 description 2
- 238000011105 stabilization Methods 0.000 description 2
- 238000004506 ultrasonic cleaning Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- 229910004261 CaF 2 Inorganic materials 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 238000000866 electrolytic etching Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 230000002147 killing effect Effects 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- VLAPMBHFAWRUQP-UHFFFAOYSA-L molybdic acid Chemical compound O[Mo](O)(=O)=O VLAPMBHFAWRUQP-UHFFFAOYSA-L 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 150000004763 sulfides Chemical class 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 238000009849 vacuum degassing Methods 0.000 description 1
- 239000006200 vaporizer Substances 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
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- 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
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- 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
- C22C38/02—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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- 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
-
- 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
- C22C38/46—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
-
- 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
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/13—Modifying the physical properties of iron or steel by deformation by hot working
Definitions
- the present invention relates to a duplex stainless steel material and a duplex stainless steel pipe used in an environment containing a corrosive substance such as chloride, hydrogen sulfide, carbon dioxide gas (hereinafter sometimes referred to as a corrosive environment).
- a corrosive substance such as chloride, hydrogen sulfide, carbon dioxide gas
- Stainless steel is a material that naturally forms a stable surface film mainly composed of Cr oxide called a passive film in a corrosive environment and exhibits corrosion resistance.
- a duplex stainless steel material composed of a ferrite phase and an austenite phase is superior in strength characteristics to austenitic stainless steel and ferritic stainless steel, and has good pitting corrosion resistance and stress corrosion cracking resistance. Due to these characteristics, duplex stainless steel materials are used for structural materials in corrosive environments such as oil well pipes and various chemical plants, including structural materials for seawater environments such as umbilicals, seawater desalination plants, and LNG vaporizers. It is used as
- the duplex stainless steel material starts from inclusions in the duplex stainless steel material and defects in the passive film. In some cases, so-called pitting corrosion may occur.
- corrosive substances such as chloride ions are concentrated inside the gap, resulting in a more severe corrosive environment, and an oxygen concentration cell is formed between the outside and inside of the gap, Local corrosion inside the crevice is further promoted, and so-called crevice corrosion may occur.
- local corrosion such as pitting corrosion and crevice corrosion often becomes the starting point of stress corrosion cracking (SCC), and further improvement in corrosion resistance, particularly local corrosion resistance, is required from the viewpoint of safety.
- SCC stress corrosion cracking
- the pitting corrosion resistance of stainless steel is as follows: Cr amount (% by mass) is [Cr], Mo amount (% by mass) is [Mo], W amount (% by mass) is [W], and N amount (% by mass) is [N]. ],
- the pitting corrosion index PRE Pultting Resistance Equivalent calculated by [Cr] +3.3 [Mo] +16 [N], or [C] +3.3 ([Mo] +0. 5 [W]) + 16 [N]. It is known that if the content of Cr, Mo, N is increased, excellent pitting corrosion resistance can be obtained.
- the addition amounts of Cr, Mo, N, and W are adjusted so that PRE (or PREW) is 35 or more in normal duplex stainless steel, and 40 or more in super duplex stainless steel. Further, it is known that an increase in the content of Cr, Mo, and N contributes to an improvement in crevice corrosion resistance.
- Patent Document 1 discloses a duplex stainless steel excellent in corrosion resistance having a PREW of 40 or more by controlling the contents of Cr, Mo, N, and W.
- Patent Document 2 discloses a duplex stainless steel that controls the contents of B and Ta in addition to controlling the contents of Cr, Mo, W, and N, and is excellent in corrosion resistance and hot workability.
- Patent Document 3 in addition to controlling the contents of Cr, Mo, W, and N, the contents of Ti, V, Nb, Ta, Zr, and B are controlled, and two phases that are excellent in corrosion resistance and hot workability Stainless steel is disclosed.
- Patent Document 4 assuming that Cr and N are particularly effective in improving crevice corrosion resistance, a duplex stainless steel excellent in crevice corrosion resistance and overhang formability is obtained while saving Ni which increases the cost. Disclosure. Patent Document 5 discloses a duplex stainless steel in which Cu and Al are added and the amounts of O, S, and Ca are controlled to improve crevice corrosion resistance.
- Patent Document 6 in order to reduce sulfide inclusions in steel that adversely affect hot workability and corrosion resistance, a CaO crucible and a CaO—CaF 2 —Al 2 O 3 slag are used in a vacuum melting furnace. The amount of S is reduced to 3 ppm or less.
- Patent Document 7 as a technique for controlling oxide inclusions as a starting point of pitting corrosion, the total content of Ca and Mg in the oxide inclusions, the S content is controlled, and the inclusion form And duplex stainless steels with adjusted density are disclosed. And in Patent Document 7, since insoluble Al oxide containing Ca, Mg, S more than a certain amount becomes a local corrosion starting point, slag basicity at the time of reduction treatment, killing temperature and time in the ladle, A duplex stainless steel is disclosed in which the size and number of the inclusions are controlled by optimally combining the total processing ratio after casting and the occurrence of local corrosion is suppressed.
- Patent Document 1 the corrosion resistance (pitting corrosion resistance) of a steel material is evaluated by a pitting potential in 80 ° C., 20% -NaCl.
- Patent Document 2 B is added to the steel, but B combines with N in the steel to produce BN, which may reduce the N concentration contributing to corrosion resistance. Further, in Patent Document 2, the added amount of W is as high as 5 to 10% by mass, which causes an increase in cost and is economically disadvantageous.
- Nb, Ti, and Zr are added to the steel, but these elements combine with N in the steel to form nitrides, thereby reducing the N concentration that contributes to corrosion resistance. There is a risk of letting you. Moreover, when the produced
- the duplex stainless steel disclosed in Patent Document 4 assumes the use of automobile materials, and is insufficient in crevice corrosion resistance in severe corrosive environments such as oil wells.
- the duplex stainless steel disclosed in Patent Document 5 has been evaluated for crevice corrosion resistance in artificial seawater at 30 ° C., and crevice corrosion resistance is insufficient in severe corrosive environments such as oil wells.
- Patent Document 6 it is evaluated that S is 3 ppm or less because the industrial load is large and the cost is high, and that the critical pitting corrosion temperature is 35 ° C. or more is excellent in corrosion resistance. This is considered insufficient for use in severe corrosive environments.
- Patent Document 7 even if Ca and Mg are added and inclusions are controlled, there is a concern that these may aggregate to cause local corrosion and crack initiation, and the present invention basically uses conventional pores. It is a direction to reduce the inclusions that serve as the starting point of the erosion, and excessively reducing O and S that are the source of formation is industrially expensive and expensive.
- duplex stainless steel materials are excellent in strength characteristics, but are often more difficult to process such as rolling and drawing than ordinary stainless steel materials. Furthermore, since sigma phase precipitation is promoted by an increase in Cr and Mo added for the purpose of improving corrosion resistance, there is a concern that hot workability may be insufficient depending on the application.
- the present invention has been made in view of such a situation, and the problem is that a duplex stainless steel material that exhibits good corrosion resistance in an environment containing corrosive substances such as chloride, hydrogen sulfide, and carbon dioxide gas.
- a duplex stainless steel material that also exhibits good hot workability, and to provide a duplex stainless steel tube that exhibits good corrosion resistance by using such a duplex stainless steel material There is to do.
- the stainless steel material is a material that exhibits corrosion resistance by a passive film mainly composed of Cr oxide. Since duplex stainless steel is generally composed of a ferrite phase and an austenite phase, there is discontinuity at the interface between these different phases, and the passive film becomes unstable at the interface between the ferrite phase and the austenite phase. Therefore, it is easy to receive a passive film destruction action of chloride ions, and local corrosion is likely to occur. In order to solve the above-mentioned problems, the present inventors pay attention to enhancing the stability and protective property of the passive film of the duplex stainless steel material within a range that does not impair the manufacturing surface and various characteristics, and improve the corrosion resistance. Technical study was conducted.
- the stainless steel material is a material that exhibits corrosion resistance by the passive film mainly composed of Cr oxide
- the present inventors have studied from the viewpoint of improving the effective Cr concentration in the steel.
- the formation of unnecessary Cr inclusions in the steel results in a decrease in the effective Cr concentration in the steel, and it has been found that a method for suppressing the precipitation of unnecessary Cr inclusions is effective. .
- the pitting corrosion resistance of the stainless steel material is expressed by the pitting corrosion index PRE (W) including the N amount ([N]), and therefore the effective N concentration in the steel also affects the improvement of the corrosion resistance. Therefore, examination was also performed from the viewpoint of suppressing the precipitation of unnecessary N-based inclusions.
- the effective concentration of Cr and N in steel is increased by moderately adding Ta as an element that has a high ability to fix unnecessary C in steel and that is difficult to fix N necessary for ensuring corrosion resistance.
- Ta as an element that has a high ability to fix unnecessary C in steel and that is difficult to fix N necessary for ensuring corrosion resistance.
- Mo is known as an additive element for improving corrosion resistance.
- Mo is known as an additive element for improving corrosion resistance.
- Mo becomes an acidic environment in the pit, it elutes as ions and repairs the passive film (repassivation). Effect). Therefore, the inventors focused on this effect and extracted an element that elutes ions similar to Mo in an acidic environment.
- Ge has an electrochemical property in the acidic region close to Mo, and has a function of enhancing the re-passivation ability of stainless steel and improving local corrosion resistance by adding moderately. .
- the duplex stainless steel material according to the present invention is a duplex stainless steel material composed of a ferrite phase and an austenite phase.
- the component composition of the duplex stainless steel material is C: 0.100% by mass or less, Si: 0.10 To 2.00% by mass, Mn: 0.10 to 2.00% by mass, P: 0.050% by mass or less, S: 0.0100% by mass or less, Al: 0.001 to 0.050% by mass, Ni : 1.0 to 10.0% by mass, Cr: 22.0 to 28.0% by mass, Mo: 2.0 to 6.0% by mass, N: 0.20 to 0.50% by mass, Furthermore, it contains at least one selected from Ta: 0.01 to 0.50 mass% and Ge: 0.1 to 1.0 mass%, with the balance being Fe and inevitable impurities. And
- the duplex stainless steel material includes a predetermined amount of C, Si, Mn, P, S, Al, Ni, Cr, Mo, N, and Ta and / or Ge, thereby improving the corrosion resistance. . Moreover, when Ta is selected as the contained element, a decrease in hot workability is also suppressed.
- the duplex stainless steel material according to the present invention contains the Ta, limits the impurity O to 0.01% by mass or less, and, among the inclusions of the duplex stainless steel material, has a long diameter.
- the number of sulfur / oxide composite inclusions containing Ta that is 1 ⁇ m or more is 500 or less per 1 mm 2 in cross section perpendicular to the processing direction, and the Ta content of the sulfur / oxide composite inclusions is 5 atomic%. It is preferable to make it as described above. By doing so, the corrosion resistance is further improved.
- the component composition is further Co: 0.10 to 2.00% by mass, Cu: 0.10 to 2.00% by mass, V: 0.01 to 0.50% by mass. %, Ti: 0.01 to 0.50 mass%, and Nb: 0.01 to 0.50 mass%.
- the duplex stainless steel material further improves the corrosion resistance by further containing at least one selected from the group consisting of Co, Cu, V, Ti, and Nb.
- Co and Cu contribute to stabilization of the austenite phase
- V, Ti and Nb contribute to improvement of strength characteristics and hot workability.
- duplex stainless steel material according to the present invention further includes one or two of the above-mentioned component compositions of Mg: 0.0005 to 0.0200 mass% and Ca: 0.0005 to 0.0200 mass%. It is preferable to do.
- the duplex stainless steel material further contains a predetermined amount of Mg, Ca, or two kinds of coarse MnS or the like which becomes a passive film deficient portion that tends to start local corrosion. Formation of inclusions is suppressed and local corrosion resistance is improved. Moreover, hot workability improves by the production
- duplex stainless steel pipe according to the present invention is characterized by comprising the duplex stainless steel material described above.
- the duplex stainless steel pipe is made of a duplex stainless steel material, which increases the stability of the passive film formed on the surface of the steel pipe, so that local corrosion can be greatly suppressed and corrosion resistance is improved. To do.
- duplex stainless steel material of the present invention exhibits good corrosion resistance in an environment containing corrosive substances such as chloride, hydrogen sulfide and carbon dioxide. Moreover, when it contains Ta, favorable hot workability is also expressed. Furthermore, the duplex stainless steel pipe of the present invention exhibits good corrosion resistance in an environment containing corrosive substances such as chloride, hydrogen sulfide and carbon dioxide. As a result, duplex stainless steel pipes can be used not only for structural materials in seawater environments such as umbilicals, seawater desalination plants, and LNG vaporizers, but also for structural materials in highly corrosive environments such as oil well pipes and various chemical plants. It becomes possible.
- the duplex stainless steel material of the present invention is a duplex stainless steel material composed of a ferrite phase and an austenite phase, and the component composition of the duplex stainless steel material is C, Si, Mn, P, S, Al, Ni, Cr , Mo and N are contained in a predetermined amount, and Ta and / or Ge are contained in a predetermined amount, with the balance being Fe and inevitable impurities.
- the component composition of the duplex stainless steel material is C, Si, Mn, P, S, Al, Ni, Cr , Mo and N are contained in a predetermined amount, and Ta and / or Ge are contained in a predetermined amount, with the balance being Fe and inevitable impurities.
- the duplex stainless steel material of the present invention is composed of two phases of a ferrite phase and an austenite phase.
- ferrite phase stabilizing elements such as Cr and Mo tend to concentrate in the ferrite phase
- austenite phase stabilizing elements such as Ni and N tend to concentrate in the austenite phase.
- the area ratio of the ferrite phase to the austenite phase is less than 30% or more than 70%, the concentration difference between the ferrite phase and the austenite phase of elements contributing to the corrosion resistance such as Cr, Mo, Ni, and N becomes large.
- the area ratio of the ferrite phase and the austenite phase is also optimized, and the area ratio of the ferrite phase is preferably 30 to 70% and more preferably 40 to 60% from the viewpoint of corrosion resistance.
- Such an area ratio between the ferrite phase and the austenite phase can be optimized by adjusting the contents of the ferrite phase stabilizing element and the austenite phase stabilizing element.
- duplex stainless steel material of the present invention other phases such as ⁇ phase and Cr carbonitride as well as ferrite phase and austenite phase can be tolerated to such an extent that various properties such as corrosion resistance and mechanical properties are not harmed.
- the total area of the ferrite phase and the austenite phase is preferably 95% or more, and more preferably 97% or more.
- C 0.100 mass% or less
- C is a harmful element because it forms a carbide with Cr or the like in the steel material to lower the corrosion resistance and hot workability. Therefore, the C content is 0.100% by mass or less.
- the C content is preferably 0.080% by mass or less, more preferably 0.060% by mass or less. Note that C may not be contained in the steel material, that is, 0% by mass.
- Si 0.10 to 2.00% by mass
- Si content shall be 0.10 mass% or more.
- the preferable lower limit of the Si content is 0.15% by mass, and more preferably 0.20% by mass.
- the upper limit with preferable Si content is 1.50 mass%, and a more preferable upper limit is 1.00 mass%.
- Mn has a deoxidizing effect like Si, and is an element necessary for ensuring strength. In order to acquire such an effect, Mn content shall be 0.10 mass% or more. However, if Mn is excessively contained, coarse MnS is formed and the corrosion resistance and hot workability deteriorate, so the Mn content is 2.00% by mass or less.
- the lower limit with preferable Mn content is 0.15 mass%, More preferably, it is 0.20 mass%.
- the upper limit with preferable Mn content is 1.50 mass%, More preferably, it is 1.00 mass%.
- P 0.050 mass% or less
- P is an impurity mixed during melting, an element harmful to corrosion resistance, and an element that deteriorates weldability and workability. Therefore, the P content is 0.050 mass% or less.
- the P content is preferably 0.040% by mass or less, and more preferably 0.030% by mass or less.
- P may not be contained in the steel material, that is, it may be 0% by mass. However, excessive reduction of the P content causes an increase in production cost, so the lower limit of P content in actual operation. The value is 0.010% by mass.
- S 0.0100 mass% or less
- S is an impurity mixed during melting, and is an element that combines with Mn or the like to form sulfide inclusions and degrades corrosion resistance and hot workability. Therefore, the S content is 0.0100% by mass or less. Since the S content is preferably as small as possible, it is preferably 0.0030% by mass or less. Further, S is not contained in the steel material, that is, it may be 0% by mass. However, excessive reduction of the S content causes an increase in manufacturing cost, so the lower limit value in actual operation of the S content. Is 0.0001 mass%.
- Al 0.001 to 0.050 mass%
- Al has an effect of deoxidation, and is an element necessary for reducing the amount of oxygen during melting.
- Al content shall be 0.001 mass% or more.
- the Al content is set to 0.050% by mass or less.
- a preferred range for the Al content is 0.010 to 0.020 mass%.
- Ni is an element necessary for improving corrosion resistance, and is particularly effective for suppressing local corrosion in a chloride environment. Ni is also an element that is effective for improving low-temperature toughness and is also necessary for stabilizing the austenite phase. In order to acquire such an effect, Ni content shall be 1.0 mass% or more. However, if Ni is excessively contained, the austenite phase is excessively increased and the strength is lowered, and an intermetallic compound ( ⁇ phase) is easily generated and hot workability is deteriorated. 0.0 mass% or less.
- the lower limit with preferable Ni content is 2.0 mass%, More preferably, it is 3.0 mass%.
- the upper limit with preferable Ni content is 9.5 mass%, More preferably, it is 9.0 mass%.
- Cr is a main component of the passive film, and is a basic element for developing the corrosion resistance of the stainless steel material. Cr is also an element that stabilizes the ferrite phase. In order to maintain the two-phase structure of the ferrite phase and the austenite phase to achieve both corrosion resistance and strength, the Cr content is set to 22.0% by mass or more. However, when Cr is excessively contained, an intermetallic compound ( ⁇ phase) is easily generated and hot workability is deteriorated, so the Cr content is set to 28.0% by mass or less.
- the lower limit with preferable Cr content is 23.0 mass%, More preferably, it is 24.0 mass%.
- the upper limit with preferable Cr content is 27.5 mass%, More preferably, it is 27.0 mass%.
- Mo is an element that generates molybdic acid at the time of dissolution and exhibits an effect of improving local corrosion resistance by an inhibitor action, thereby improving the corrosion resistance.
- Mo is also an element that stabilizes the ferrite phase and is an element that improves the pitting corrosion resistance and crack resistance of the steel material.
- Mo content shall be 2.0 mass% or more.
- the Mo content is set to 6.0% by mass or less.
- the lower limit with preferable Mo content is 2.2 mass%, More preferably, it is 2.5 mass%.
- the upper limit with preferable Mo content is 5.5 mass%, More preferably, it is 5.0 mass%.
- N is an element that stabilizes a strong austenite phase, has an effect of improving corrosion resistance without increasing the formation sensitivity of the ⁇ phase, and is also an element effective for increasing the strength of a steel material.
- N content shall be 0.20 mass% or more.
- the N content is 0. .50% by mass or less.
- the lower limit with preferable N content is 0.22 mass%, More preferably, it is 0.25 mass%.
- the upper limit with preferable N content is 0.45 mass%, More preferably, it is 0.40 mass%.
- Ta 0.01 to 0.50 mass%
- Ta content shall be 0.01 mass% or more.
- Ta content shall be 0.01 mass% or more.
- Ta content is 0.50% by mass or less.
- a preferable lower limit of the Ta content is 0.02% by mass, and more preferably 0.03% by mass.
- the upper limit with preferable Ta content is 0.30 mass%, More preferably, it is 0.25 mass%.
- Ge 0.1 to 1.0% by mass
- Ge has the effect of improving local corrosion resistance by increasing and stabilizing the Cr concentration in the passive film.
- 0.1 mass% or more Preferably 0.2 mass% or more is added.
- the upper limit is made 1.0% by mass or less, preferably 0.9% by mass or less.
- either Ta or Ge may be contained. However, when it is desired to improve the hot workability, it is preferable to select Ta.
- Inevitable impurities can be contained to the extent that they do not harm the properties of the duplex stainless steel material. For example, if it is O, the content is 0.1 mass% or less, preferably 0.05 mass% or less. Moreover, although mentioned later for details, when it contains Ta, it is more preferable to make O amount into 0.01 mass% or less. Thereby, the corrosion resistance manifesting effect of the present invention can be maximized.
- the duplex stainless steel material of the present invention may further contain other elements as long as the effects of the present invention are not adversely affected.
- the component composition preferably further contains one or more kinds from a group consisting of a predetermined amount of Co, Cu, V, Ti, and Nb.
- Co and Cu are elements that improve the corrosion resistance and stabilize the austenite phase.
- the content of these elements is 0.10% by mass or more.
- a preferable lower limit of the content of these elements is 0.20% by mass.
- the preferable upper limit of content of these elements is 1.50 mass%.
- V, Ti and Nb are elements that improve the corrosion resistance and improve the strength characteristics and hot workability.
- the content of these elements is 0.01% by mass or more.
- V, Ti, and Nb are excessively contained, coarse carbides and nitrides are formed and the toughness is deteriorated. Therefore, the content of these elements is set to 0.50% by mass or less.
- a preferable lower limit of the content of these elements is 0.05% by mass.
- the preferable upper limit of content of these elements is 0.40 mass%.
- the component composition preferably further contains one or two kinds of Mg and Ca in predetermined amounts.
- Mg and Ca are combined with S or O contained in the steel as impurities, and suppress the formation of inclusions such as MnS and Al 2 O 3 , thereby improving the hot workability.
- the content of these elements is 0.0005% by mass or more.
- excessive inclusion of Mg and Ca leads to an increase in oxide inclusions, and these inclusions serve as starting points for pitting corrosion and cracking, so that corrosion resistance and hot workability deteriorate.
- the element content is 0.020% by mass or less.
- a preferable content of these elements is 0.002 to 0.020 mass%.
- the duplex stainless steel material according to the present invention has a composition of [Cr] +3.3 [Mo] when the Cr content is [Cr], the Mo content is [Mo], and the N content is [N]. ] +16 [N] ⁇ 40 is preferable.
- [Cr] +3.3 [Mo] +16 [N] is a pitting corrosion resistance index (PRE: Pitting Resistance Equivalent) which is conventionally known as an index representing the corrosion resistance of steel materials.
- PRE Pitting Resistance Equivalent
- sulfide inclusions (MnS) contained in normal stainless steel are modified into sulfur / oxide composite inclusions containing Ta. Then, the local corrosion resistance is improved by the sulfur / oxide composite inclusions containing Ta.
- the Ta content of the sulfur-oxide composite inclusions containing Ta is 5 atomic% or more, preferably 7 atomic% or more, more preferably 10 atomic% or more.
- the upper limit of Ta content is not specifically defined, it is about 50 atomic%.
- the number of oxide-based composite oxides is 500 or less, preferably 450 or less, more preferably 400 or less per 1 mm 2 in cross section perpendicular to the processing direction.
- the lower limit of the number density of the sulfur / oxide composite inclusions containing Ta is not particularly defined, but is about 20 per 1 mm 2 . Fine inclusions whose major axis is less than 1 ⁇ m are excluded from the target because they have a low degree of adverse effect on local corrosion resistance.
- the Ta content and number density of such sulfur / oxide composite inclusions control the Ta content and O content of the duplex stainless steel, and also control the thermal processing conditions during steel production. Is achieved by doing
- the duplex stainless steel material according to the present invention is manufactured by a manufacturing facility and a manufacturing method used for mass production of a normal stainless steel material. can do.
- the molten steel melted in a converter or electric furnace is refined by an AOD method, a VOD method, or the like to adjust the components, and then formed into a steel ingot by a casting method such as a continuous casting method or an ingot-making method.
- the obtained steel ingot can be hot-worked in a temperature range of about 1000 ° C. to 1200 ° C., and then cold-worked to obtain a desired dimensional shape.
- the solution heat treatment temperature is preferably 1000 to 1100 ° C.
- the holding time is preferably 10 to 30 minutes
- the rapid cooling is preferably performed at a cooling rate of 10 ° C./second or more.
- the pickling for surface adjustments, such as scale removal can be performed as needed.
- duplex stainless steel material of the present invention when the above-described control of the sulfur / oxide composite inclusion is performed, it is manufactured as follows.
- deoxidation is performed by adding a large amount of elements having a high affinity with O, such as Si and Al, and further, vacuum degassing, argon gas stirring, etc. Oxide inclusions are removed by increasing the time of secondary refining or by performing it multiple times.
- the steel ingot is obtained by a casting method such as a continuous casting method or an ingot forming method. To do.
- the obtained steel ingot can be hot-worked in a temperature range of about 1000 to 1200 ° C. and then cold-worked to obtain a desired size and shape.
- the total working ratio during hot working (the cross-sectional area of the original steel ingot / the cross-sectional area after working) is about 10 to 50 as usual, but a sulfur / oxide-based composite containing a desired Ta
- the processing ratio cross-sectional area before processing / cross-sectional area after processing
- the temperature range of 1100 to 1200 ° C. during hot processing is 50% of the total processing ratio. It is preferable to perform hot working so that the working ratio exceeds.
- the steel ingot is hot-worked in a temperature range of about 1000 to 1200 ° C. Due to the influence of the temperature drop at the time, the processing ratio in the temperature range of 1000 to 1100 ° C. is higher than the processing ratio in the temperature range of 1100 to 1200 ° C. As a result, in the conventional manufacturing, the processing ratio in the temperature range of 1100 to 1200 ° C. is 50% or less of the total processing ratio.
- a desired ratio of sulfur / oxide composite containing Ta is obtained by deliberately increasing the processing ratio in the temperature range of 1100 to 1200 ° C. The presence of inclusions is obtained.
- the duplex stainless steel pipe of the present invention is made of the duplex stainless steel material, and can be produced by a production facility and a production method used for mass production of ordinary stainless steel pipes.
- a desired size can be obtained by an extruded pipe made of a round bar, a Mannesmann pipe, a welded pipe made by welding a seam after forming a plate material.
- the dimensions of the duplex stainless steel pipe can be appropriately set according to the umbilical, the seawater desalination plant, the LNG vaporizer, the oil well pipe, various chemical plants, etc. in which the steel pipe is used.
- duplex stainless steel material according to the present invention examples of the duplex stainless steel material according to the present invention will be described below.
- Example 1 Example of Ta-containing steel
- Sample preparation Steels (steel symbols A to Z) having the composition shown in Table 1 were melted by a molten steel processing facility having an electrode arc heating function, and cast using a 50 kg round mold (main body: about ⁇ 140 ⁇ 320 mm). The solidified steel ingot is heated to 1200 ° C., hot forged at the same temperature, then cut, subjected to a solution heat treatment held at 1100 ° C. for 30 minutes, water cooled, and a forged steel product of 600 ⁇ 120 ⁇ 60 mm (sample No. .1 to 26).
- each forged steel product was embedded in a cross section parallel to the processing direction, mirror-polished, electrolytically etched in an oxalic acid aqueous solution, and then observed with an optical microscope at a magnification of 100 times to confirm the structure of each forged steel product. .
- each forged steel product was composed of two phases of a ferrite phase and an austenite phase.
- the sample surface was wet-polished with SiC # 600 abrasive paper, subjected to ultrasonic cleaning, and then immersed in 30% nitric acid at 50 ° C. for 1 hour for passivation treatment.
- a lead wire was attached to the sample by spot welding, and the test part (test area: 10 mm ⁇ 10 mm) was left and covered with an epoxy resin.
- the sample was immersed in a 20% NaCl aqueous solution maintained at 80 ° C. for 10 minutes, then held at +600 mV (vs. SCE: saturated calomel electrode) for 1 minute, and the maximum pitting depth of the test part was measured with a laser microscope. did.
- Sample No. In No. 19 since Ta was excessive, a large amount of coarse nitride was formed, and the hot workability was poor. Also, a ⁇ phase was formed, and the pitting corrosion resistance was poor. Sample No. In No. 20, Ta was not added, so many ⁇ phases were formed, and the pitting corrosion resistance and hot workability were inferior. Sample No. In No. 21, since Mn was excessive, a large number of inclusions (MnS) were precipitated, resulting in poor pitting corrosion resistance and hot workability. Sample No. In No. 22, since S was excessive, a large amount of coarse sulfide was formed, and pitting corrosion resistance and hot workability were inferior. Sample No. No. 23 was inferior in pitting corrosion resistance and hot workability due to lack of Cr. Sample No.
- Example 2 Example of Ge-containing steel
- Stainless steel with the component composition shown in Table 3 (the remainder is Fe and inevitable impurities) are melted by molten steel processing equipment equipped with an electrode arc heating function, and a 50 kg square mold (main body: about ⁇ 120 x 450 mm) is used. And cast.
- Table 3 also shows the result of calculating the PRE value for each steel structure. In Table 3, a blank indicates that the corresponding component is not contained.
- the solidified steel ingot was heated to 1200 ° C. and hot forged at the same temperature to finish a forged steel product of 600 ⁇ 120 ⁇ 60 mm. Then, it cut
- crevice corrosion resistance was evaluated by the following procedure using a sample (20 mm ⁇ 30 mm ⁇ 2 mmt) collected from the forged steel product in parallel with the processing direction.
- crevice corrosion resistance The evaluation of crevice corrosion resistance was performed by immersing a test piece provided with a gap in 6% FeCl 3 + 0.05N HCl for 24 hours in accordance with ASTM G48 Method F, and measuring the maximum crevice corrosion depth after the test. evaluated. The test temperature was 60 ° C.
- the maximum crevice corrosion depth was judged to be excellent when it was less than 200 ⁇ m, then good when it was 200 ⁇ m or more and less than 400 ⁇ m, and poor when it was 400 ⁇ m or more. The results are shown in Table 3.
- Component composition The component composition was measured by the following method. C, S; infrared absorption method, Si, Mn, P, Ni, Cr; fluorescent X-ray analysis method; Mo, Sn, Ge, Ta; ICP analysis method, S, N; inert gas melting method.
- C S
- infrared absorption method Si, Mn, P, Ni, Cr
- fluorescent X-ray analysis method Mo, Sn, Ge, Ta
- ICP analysis method S, N
- inert gas melting method The measurement site
- compositions that do not satisfy the provisions of the present invention are indicated by underlining the numerical values.
- composition symbols B1 to B5 (test materials No. 13 to 17) have the following problems.
- B1 a large amount of Ge was added, the ⁇ phase increased, and the crevice corrosion resistance deteriorated.
- B2 since no Ge was added, the passive film was unstable, and the crevice corrosion resistance was deteriorated.
- B3 and B4 each contain a large amount of S and Mn, a large number of Mn sulfides were precipitated, and the crevice corrosion resistance was deteriorated.
- B5 had a small amount of N, and the crevice corrosion resistance was deteriorated.
- Example 3 Example in which Ta-containing steel is subjected to control of sulfur-oxide composite inclusions
- Steel with the composition shown in Table 4 (steel symbols: A1 to A16, B1 to B9) is melted by molten steel processing equipment equipped with an electrode arc heating function, and a 50 kg round mold (main body: about ⁇ 140 ⁇ 320 mm) is prepared. Used to cast.
- a blank indicates that the corresponding component is not contained, and the balance is Fe and inevitable impurities.
- the solidified steel ingot was heated to 1200 ° C., subjected to hot forging (forging temperature: 1000 to 1200 ° C.) at the same temperature, and then cut. Next, cold rolling and a solution heat treatment at 1100 ° C. for 30 minutes were performed, and after cooling with water at a cooling rate of 12 ° C./second, the steel was cut into 300 ⁇ 120 ⁇ 10 mm steel materials (No. 1 to 25).
- hot forging at 1100 to 1200 ° C. was performed at a processing ratio exceeding 50% of the total processing ratio of hot forging.
- hot forging at 1100 to 1200 ° C. was performed at a processing ratio of 50% or less of the total processing ratio of hot forging.
- Example collection Next, using a sample (20 mm ⁇ 30 mm ⁇ 2 mmt) taken from the steel material in parallel with the processing direction, the number density and Ta content of the sulfur / oxide composite inclusions are measured by the following procedure. The pitting corrosion resistance and hot workability were evaluated. The results are shown in Table 5.
- the sample was embedded in a cross section perpendicular to the processing direction, mirror-polished, subjected to electrolytic etching in an aqueous oxalic acid solution, and then observed with an optical microscope at a magnification of 100 to observe the structure of each sample.
- all samples consisted of two phases of a ferrite phase and an austenite phase.
- the major axis (equivalent circle diameter), number density and Ta content of inclusions can be measured by the following procedure. That is, with respect to the sample used for the tissue observation, the surface of the sample was subjected to SEM-EPMA (scanning electron microscope-electron probe microanalyzer, “JXA-8900RL”, “XM-Z0043T”, “XM-Z0043T”, “ XM-87562 "), and the composition of the observed inclusions is analyzed by EDX (energy dispersive X-ray detector).
- SEM-EPMA scanning electron microscope-electron probe microanalyzer, “JXA-8900RL”, “XM-Z0043T”, “XM-Z0043T”, “ XM-87562 "
- the component composition analysis by EDX may be performed for inclusions having a major axis of 1 ⁇ m or more, and the center of gravity of the inclusions may be automatically analyzed in about 10 seconds per point. Inclusions whose major axis is less than 1 ⁇ m have a low adverse effect on local corrosion resistance. Therefore, in the present invention, in order to improve the measurement efficiency, inclusions whose major axis is less than 1 ⁇ m are excluded from the measurement target.
- the sulfide inclusions having a major axis of 1 ⁇ m or more observed in an automatic EPMA according to the above procedure and a measurement area of 3 mm 2 and for the oxide inclusions, the number density and the Ta content of each inclusion were measured and determined as the average value.
- the component composition satisfies the requirements of the present invention, but the processing ratio of hot forging at 1100 to 1200 ° C. is 50% or less of the total processing ratio.
- the Ta content of the oxide-based composite inclusion is less than the lower limit, and is superior in pitting corrosion resistance as compared with conventional steels that do not contain Ta. Compared with 1 to 16, the properties were slightly inferior because no sulfur / oxide composite inclusions were formed.
- the comparative example (steel material No. 18) was inferior in pitting corrosion resistance because Ta was not contained, and the sulfur / oxide composite inclusions were not modified.
- the comparative example (steel material No. 19) since the Ta content exceeded the upper limit, the sulfur / oxide composite inclusion was modified, but the number density exceeded the upper limit, and at the same time coarse nitrides were precipitated. The pitting corrosion resistance and hot workability were inferior.
- the Ta content of the sulfur / oxide composite inclusion is less than the lower limit, and the number density also exceeds the upper limit.
- a large number of Cr-based oxides were deposited, so that the pitting corrosion resistance is superior to conventional steels not containing Ta. Compared with 1 to 16, the properties were slightly inferior because no sulfur / oxide composite inclusions were formed.
- Comparative Example (steel material No. 21) was inferior in pitting corrosion resistance because the Cr content was less than the lower limit.
- Comparative Example (steel material No. 24) was inferior in pitting corrosion resistance because the Mo content was less than the lower limit.
- the comparative example (steel material No. 25) was inferior in pitting corrosion resistance because the N content was less than the lower limit.
- duplex stainless steel material and duplex stainless steel pipe of the present invention have been described.
- the present invention is not limited by the embodiments and examples, and is appropriately within a range that can meet the spirit of the present invention. It is also possible to carry out with modification, and they are all included in the technical scope of the present invention.
- duplex stainless steel material of the present invention is useful as a structural material for highly corrosive environments such as oil well pipes and various chemical plants, including structural materials for seawater environments such as umbilicals, seawater desalination plants, and LNG vaporizers. .
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Abstract
Description
PRE=[Cr]+3.3[Mo]+16[N]
本発明に係る二相ステンレス鋼材の実施形態について詳細に説明する。
本発明の二相ステンレス鋼材は、フェライト相とオーステナイト相の二相からなるものである。フェライト相とオーステナイト相からなる二相ステンレス鋼材においては、CrやMo等のフェライト相安定化元素はフェライト相に濃縮し、NiやN等のオーステナイト相安定化元素はオーステナイト相に濃縮する傾向にある。このとき、フェライト相のオーステナイト相に対する面積比が30%未満または70%を超える場合には、Cr、Mo、Ni、N等の耐食性に寄与する元素のフェライト相とオーステナイト相における濃度差異が大きくなりすぎて、フェライト相とオーステナイト相のいずれか耐食性に劣る側が選択腐食されて耐食性が劣化する傾向が大きくなる。したがって、フェライト相とオーステナイト相との面積比も最適化することが推奨され、フェライト相の面積比は、耐食性の観点から30~70%が好ましく、40~60%がさらに好ましい。このようなフェライト相とオーステナイト相の面積比は、フェライト相安定化元素とオーステナイト相安定化元素の含有量を調整することによって適正化することが可能である。
(C:0.100質量%以下)
Cは、鋼材中でCr等との炭化物を形成して耐食性および熱間加工性を低下させるため、有害な元素である。そのため、C含有量は0.100質量%以下とする。なお、C含有量はできる限り少ない方が良いため、好ましくは0.080質量%以下、より好ましくは0.060質量%以下である。なお、Cは、鋼材中に含有されていない、すなわち、0質量%であっても良い。
Siは、脱酸とフェライト相の安定化のために必要な元素である。このような効果を得るため、Si含有量は0.10質量%以上とする。しかし、過剰にSiを含有させると熱間加工性が劣化することから、Si含有量は2.00質量%以下とする。Si含有量の好ましい下限値は0.15質量%であり、さらに好ましくは0.20質量%である。また、Si含有量の好ましい上限値は1.50質量%であり、さらに好ましい上限値は1.00質量%である。
Mnは、Siと同様に脱酸効果があり、さらに強度確保のために必要な元素である。このような効果を得るため、Mn含有量は0.10質量%以上とする。しかし、過剰にMnを含有させると粗大なMnSを形成して耐食性および熱間加工性が劣化することから、Mn含有量は2.00質量%以下とする。Mn含有量の好ましい下限値は0.15質量%であり、さらに好ましくは0.20質量%である。また、Mn含有量の好ましい上限値は1.50質量%であり、さらに好ましくは1.00質量%である。
Pは、溶製時に混入する不純物であり、耐食性に有害な元素であり、また溶接性や加工性も劣化させる元素である。そのため、P含有量は0.050質量%以下とする。なお、P含有量はできる限り少ない方が良いため、好ましくは0.040質量%以下であり、さらに好ましくは0.030質量%以下である。また、Pは、鋼材中に含有されていない、すなわち、0質量%であって良いが、P含有量の過度の低減は、製造コストの上昇をもたらすので、P含有量の実操業上の下限値は0.010質量%である。
Sは、Pと同様に溶製時に混入する不純物であり、Mn等と結合して硫化物系介在物を形成して、耐食性や熱間加工性を劣化させる元素である。そのため、S含有量は0.0100質量%以下とする。なお、S含有量はできる限り少ない方が良いため、好ましくは0.0030質量%以下である。また、Sも鋼材中に含有されていない、すなわち、0質量%であってもよいが、S含有量の過度の低減は製造コストの上昇をもたらすので、S含有量の実操業上の下限値は0.0001質量%である。
Alは、Si、Mnと同様に脱酸の効果があり、溶製時の酸素量低減に必要な元素である。このような効果を得るため、Al含有量は0.001質量%以上とする。しかし、過剰にAlを含有させると酸化物系介在物を生成し耐孔食性に悪影響を及ぼすことから、Al含有量は0.050質量%以下とする。Al含有量の好ましい範囲は0.010~0.020質量%である。
Niは、耐食性向上に必要な元素であり、特に、塩化物環境における局部腐食抑制に効果が大きい。また、Niは、低温靱性を向上させるのにも有効であり、さらにオーステナイト相を安定化させるためにも必要な元素である。こうした効果を得るため、Ni含有量は1.0質量%以上とする。しかし、過剰にNiを含有させると、オーステナイト相が多くなりすぎて強度が低下すること、金属間化合物(σ相)が生成しやすくなり熱間加工性を劣化させることから、Ni含有量は10.0質量%以下とする。Ni含有量の好ましい下限値は2.0質量%であり、さらに好ましくは3.0質量%である。また、Ni含有量の好ましい上限値は9.5質量%であり、さらに好ましくは9.0質量%である。
Crは、不動態皮膜の主要成分であり、ステンレス鋼材の耐食性発現の基本元素である。また、Crは、フェライト相を安定化させる元素でもある。フェライト相とオーステナイト相の二相組織を維持して耐食性、強度を両立させるため、Cr含有量は22.0質量%以上とする。しかし、過剰にCrを含有させると金属間化合物(σ相)が生成しやすくなり熱間加工性を劣化させることから、Cr含有量は28.0質量%以下とする。Cr含有量の好ましい下限値は23.0質量%であり、さらに好ましくは24.0質量%である。また、Cr含有量の好ましい上限値は27.5質量%であり、さらに好ましくは27.0質量%である。
Moは、溶解時にモリブデン酸を生成して、インヒビター作用により耐局部腐食性を向上させる効果を発揮し、耐食性を向上させる元素である。また、Moは、フェライト相を安定化させる元素でもあり、鋼材の耐孔食性・耐割れ性を改善させる元素でもある。このような効果を得るため、Mo含有量は2.0質量%以上とする。しかし、過剰にMoを含有させるとσ相等の金属間化合物の生成を助長し、耐食性および熱間加工性を劣化させることから、Mo含有量は6.0質量%以下とする。Mo含有量の好ましい下限値は2.2質量%であり、さらに好ましくは2.5質量%である。また、Mo含有量の好ましい上限値は5.5質量%であり、さらに好ましくは5.0質量%である。
Nは、強力なオーステナイト相を安定化させる元素であり、σ相の生成感受性を増加させずに耐食性を向上させる効果があり、さらに鋼材の高強度化にも有効な元素でもある。このような効果を得るため、N含有量は0.20質量%以上とする。しかし、過剰にNを含有させると窒化物が形成され靭性や耐食性が低下すると共に、熱間加工性を劣化させ、鍛造・圧延時に耳割れや表面欠陥を生じさせることから、N含有量は0.50質量%以下とする。N含有量の好ましい下限値は0.22質量%であり、さらに好ましくは0.25質量%である。また、N含有量の好ましい上限値は0.45質量%であり、さらに好ましくは0.40質量%である。
Taは、Cと結合することでCr系炭化物の生成抑制、および靱性や耐食性の低下に影響を及ぼすσ相の析出抑制効果を有する元素であり、鋼材の実質的なCr濃度向上に寄与する効果がある。このような効果を得るため、Ta含有量は0.01質量%以上とする。しかし、過剰なTa添加は鋼中のNと結合することで窒化物として析出してしまい、靱性、熱間加工性を低下させてしまう。また、窒化物の析出によりNの実効濃度が低減し、σ相の析出により耐食性を低下させてしまう。そのため、Ta含有量は0.50質量%以下とする。Ta含有量の好ましい下限値は0.02質量%であり、さらに好ましくは0.03質量%である。また、Ta含有量の好ましい上限値は0.30質量%であり、さらに好ましくは0.25質量%である。
Geは、不動態皮膜内のCr濃度を増加させ安定化させることで、耐局部腐食性を向上させる効果を有する。このような効果を得るためには0.1質量%以上、好ましくは0.2質量%以上添加する。一方、過剰な添加は熱間加工性を劣化させ、またコストの上昇ももたらすので、その上限を1.0%質量%以下、好ましくは0.9質量%以下とする。
不可避的不純物は、二相ステンレス鋼材の諸特性を害さない程度に含有することができる。例えば、Oであれば、その含有量は0.1質量%以下であり、好ましくは0.05質量%以下である。また、詳細は後述するが、Taを含有する場合には、O量を0.01質量%以下とすることが一層好ましい。それによって、本発明の耐食性発現効果を極大化することができる。
CoおよびCuは、耐食性を向上、および、オーステナイト相を安定化させる元素である。このような効果を得るため、これらの元素の含有量は各々0.10質量%以上とする。しかし、過剰にCoおよびCuを含有させると熱間加工性が劣化することから、これらの元素の含有量は各々2.00質量%以下とする。これらの元素の含有量の好ましい下限値は、0.20質量%である。また、これらの元素の含有量の好ましい上限値は1.50質量%である。
MgおよびCaは、鋼中に不純物として含有されるSあるいはOと結合して、MnSやAl2O3等の介在物の形成を抑制して、熱間加工性を向上させる効果がある。このような効果を得るため、これらの元素の含有量は各々0.0005質量%以上とする。しかし、過剰にMgおよびCaを含有させると、酸化物系介在物の増加を招き、これら介在物が孔食や割れの起点となるために耐食性および熱間加工性が劣化することから、これらの元素の含有量は各々0.020質量%以下とする。これらの元素の好ましい含有量は、0.002~0.020質量%である。
本発明に係る二相ステンレス鋼材において、Taを含有させると共にO量を所定量(0.01質量%以下)に制御することによって、鋼中の硫・酸化物系複合介在物を改質し、耐食性を一層向上させることが可能となる。
本発明の二相ステンレス鋼材を製造する際、前記した硫・酸化物系複合介在物の制御までは行なわない場合には、通常のステンレス鋼材の量産に用いられている製造設備および製造方法によって製造することができる。例えば、転炉あるいは電気炉にて溶解した溶鋼に対して、AOD法やVOD法等による精錬を行って成分調整した後、連続鋳造法や造塊法等の鋳造方法で鋼塊とする。得られた鋼塊を1000℃~1200℃程度の温度域にて熱間加工を行い、次いで冷間加工を行って所望の寸法形状にすることができる。
本発明に係る二相ステンレス鋼管の実施形態について説明する。
(試料の作製)
電極アーク加熱機能を備える溶鋼処理設備によって、表1に示す成分組成の鋼(鋼記号A~Z)をそれぞれ溶製し、50kgの丸鋳型(本体:約φ140×320mm)を用いて鋳造した。凝固した鋼塊を1200℃まで加熱し同温度で熱間鍛造を施し、その後切断し、1100℃で30分保持の固溶化熱処理を施し、水冷して600×120×60mmの鍛鋼品(試料No.1~26)に仕上げた。
次に、鍛鋼品から加工方向に平行に採取した試料(20mm×30mm×2mm)を用いて、以下に示す手順で耐孔食性および熱間加工性を評価した。
試料表面をSiC#600研磨紙で湿式研磨し、超音波洗浄した後50℃の30%硝酸に1時間浸漬し不動態化処理をした。次に、試料にスポット溶接で導線を取り付け、試験部(試験面積:10mm×10mm)を残してエポキシ樹脂で被覆した。その試料を80℃に保持した20%NaCl水溶液中に10分間浸漬した後、+600mV(vs.SCE:飽和カロメル電極)で1分間保持し、レーザー顕微鏡にて試験部の最大孔食深さを測定した。そして、最大孔食深さが40μmを超えるものを耐孔食性が不良(×)、最大孔食深さが40μm以下で20μmを超えるものを耐孔食性が良好(〇)、最大孔食深さが20μm以下のものを耐孔食性が優れている(◎)と評価した。その結果を表2に示す。
鍛鋼品の表面を目視にて観察し、表面欠陥の有無を観察した。そして、割れが発生しているものを熱間加工性が不良(×)、表面欠陥が多発しているものを熱間加工性がやや不良(△)、表面欠陥がわずかなものを熱間加工性が良好(〇)、表面欠陥がないものを熱間加工性が優れている(◎)と評価した。その結果を表2に示す。
(試験材No.1~17の作製)
電極アーク加熱機能を備える溶鋼処理設備によって、表3に示す成分組成のステンレス鋼(残部はFeおよび不可避的不純物)をそれぞれ溶製し、50kgの角鋳型(本体:約□120×450mm)を用いて鋳造した。また、各鋼の組織についてPRE値を算出した結果も表3に示す。なお、表3において、空欄は該当成分が含有されていないことを示す。凝固した鋼塊を1200℃まで加熱し、同温度で熱間鍛造を施し、600×120×60mmの鍛鋼品に仕上げた。その後、切断し、熱処理として1100℃で30分間保持して、水冷した。
次に、前記鍛鋼品から加工方向に平行に採取した試料(20mm×30mm×2mmt)を用いて、以下に示す手順で耐すきま腐食性を評価した。
耐すきま腐食性の評価は、ASTM G48のMethod Fに従い、すきまを付与した試験片を6%FeCl3+0.05N HCl中で24時間浸漬し、試験後の最大すきま腐食深さを測定して、評価した。試験温度は60℃とした。耐すきま腐食性の評価としては、最大すきま腐食深さが、200μm未満のとき優良、次いで200μm以上で400μm未満のとき良、400μm以上のとき劣、として判定を行った。その結果を表3に示した。
成分組成は、以下の方法で測定した。C、S;赤外線吸収法、Si、Mn、P、Ni、Cr;蛍光X線分析法;Mo、Sn、Ge、Ta;ICP分析法、S、N;不活性ガス融解法。試験材の測定部位は、測定が可能であれば特に限定されない。表3中、本発明の規定を満足しない組成は、数値に下線を引いて示した。
(鋼材の作製)
電極アーク加熱機能を備える溶鋼処理設備によって、表4に示す成分組成の鋼(鋼記号:A1~A16、B1~B9)をそれぞれ溶製し、50kgの丸鋳型(本体:約φ140×320mm)を用いて鋳造した。また、各鋼について、PRE=[Cr]+3.3[Mo]+16[N]の算出結果についても表4に示す。なお、表4の成分組成欄において、空欄は該当成分が含有されていないことを示し、残部はFeおよび不可避的不純物である。
次に、前記鋼材から加工方向に平行に採取した試料(20mm×30mm×2mmt)を用いて、以下に示す手順で、硫・酸化物系複合介在物の個数密度およびTa含有量を測定すると共に、耐孔食性および熱間加工性を評価した。その結果を表5に示す。
介在物の長径(円相当直径)、個数密度およびTa含有量は、次の手順で測定できる。即ち、上記組織観察に用いた試料に対し、試料の表面について、SEM-EPMA(走査型電子顕微鏡-電子線プローブマイクロアナライザー、日本電子株式会社製「JXA-8900RL」、「XM-Z0043T」、「XM-87562」)による画像解析を行い、観察される介在物の成分組成をEDX(エネルギー分散型X線検出器)で分析する。EDXによる成分組成の分析は、長径が1μm以上の介在物を対象として行い、介在物の重心位置を1点につき10秒程度で自動分析すればよい。長径が1μm未満の介在物は、耐局部腐食性に悪影響を及ぼす度合いが低い。したがって、本発明では、測定効率を向上させるために、長径が1μm未満の介在物は測定対象から除外する。
耐孔食性の評価は、JIS G0577に記載の方法を参考にして評価した。試料表面をSiC#600研磨紙で湿式研磨し、超音波洗浄した後、スポット溶接で試料に導線の取り付けを行い、試料表面の試験面(10mm×10mm)の部分以外をエポキシ樹脂で被覆した。その試料を80℃に保持した20%NaCl水溶液中に10分間浸漬した後、20mV/minの掃引速度でアノード分極を行い、電流密度が0.1mA/cm2を超えた時点の電位を孔食電位(VC‘100)とした。耐孔食性の評価は孔食電位が500mV(vs.SCE(飽和カロメル電極))を超えるものを良好(〇)、100~500mV(vs.SCE)までのものをやや不良(△)、100mV(vs.SCE)未満のものを不良(×)として評価した。
前記試料の表面を目視にて観察し、表面欠陥の有無(◎:欠陥なし、〇:わずかに欠陥あり、△:欠陥多発、×:割れ発生)を観察した。その結果を表5に示す。
本出願は、2013年1月15日出願の日本特許出願(特願2013-004891)、2013年3月5日出願の日本特許出願(特願2013-043250)、2013年11月5日出願の日本特許出願(特願2013-229754)に基づくものであり、その内容はここに参照として取り込まれる。
Claims (5)
- フェライト相とオーステナイト相とからなる二相ステンレス鋼材であって、前記二相ステンレス鋼材の成分組成は、
C :0.100%質量以下、
Si:0.10~2.00質量%、
Mn:0.10~2.00質量%、
P :0.050質量%以下、
S :0.0100質量%以下、
Al:0.001~0.050質量%、
Ni:1.0~10.0質量%、
Cr:22.0~28.0質量%、
Mo:2.0~6.0質量%、
N :0.20~0.50質量%、を含有し、
更に、Ta:0.01~0.50質量%、及び、Ge:0.1~1.0質量%から選択される1種以上を含有し、残部がFeおよび不可避的不純物からなることを特徴とする二相ステンレス鋼材。 - Cr含有量(質量%)を[Cr]、Mo含有量(質量%)を[Mo]、N含有量(質量%)を[N]とした際に、下記式で表わされるPRE値が、40以上である請求項1に記載の二相ステンレス鋼材。
PRE=[Cr]+3.3[Mo]+16[N] - 前記Taを含有すると共に、不純物であるOを0.01質量%以下に制限し、且つ、前記二相ステンレス鋼材の介在物のうち、長径が1μm以上であるTaを含有する硫・酸化物系複合介在物が、加工方向に垂直な断面1mm2あたり500個以下であり、前記硫・酸化物系複合介在物のTa含有量が5原子%以上である請求項1に記載の二相ステンレス鋼材。
- 前記成分組成が、さらにCo:0.10~2.00質量%、Cu:0.10~2.00質量%、V:0.01~0.50質量%、Ti:0.01~0.50質量%、Nb:0.01~0.50質量%、Mg:0.0005~0.020質量%、Ca:0.0005~0.020質量%よりなる群から選ばれる1種以上を含有することを特徴とする請求項1~3のいずれか一項に記載の二相ステンレス鋼材。
- 請求項1~3のいずれか一項に記載の二相ステンレス鋼材からなることを特徴とする二相ステンレス鋼管。
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JP2013043250A JP5890342B2 (ja) | 2013-03-05 | 2013-03-05 | 二相系ステンレス鋼材および二相系ステンレス鋼管 |
JP2013-043250 | 2013-03-05 | ||
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US (1) | US20150354038A1 (ja) |
EP (1) | EP2947169A4 (ja) |
KR (1) | KR101702252B1 (ja) |
CN (1) | CN104919072B (ja) |
WO (1) | WO2014112445A1 (ja) |
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JP2016089263A (ja) * | 2014-11-11 | 2016-05-23 | 株式会社神戸製鋼所 | 二相ステンレス鋼材および二相ステンレス鋼管 |
CN106191693A (zh) * | 2015-02-17 | 2016-12-07 | 陈瑞凯 | 含锗肥粒铁不锈钢 |
EP3354762A4 (en) * | 2015-11-17 | 2019-04-24 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | DUPLEX STEEL MATERIAL AND DUPLEX STEEL TUBE |
CN116377321A (zh) * | 2023-03-24 | 2023-07-04 | 鞍钢股份有限公司 | 一种无铁素体的超纯净尿素级奥氏体不锈钢板及制备方法 |
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2016084523A (ja) * | 2014-10-29 | 2016-05-19 | 株式会社神戸製鋼所 | 二相ステンレス鋼材および二相ステンレス鋼管 |
JP2016089263A (ja) * | 2014-11-11 | 2016-05-23 | 株式会社神戸製鋼所 | 二相ステンレス鋼材および二相ステンレス鋼管 |
CN106191693A (zh) * | 2015-02-17 | 2016-12-07 | 陈瑞凯 | 含锗肥粒铁不锈钢 |
CN106191693B (zh) * | 2015-02-17 | 2018-09-04 | 陈瑞凯 | 含锗肥粒铁不锈钢 |
EP3354762A4 (en) * | 2015-11-17 | 2019-04-24 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | DUPLEX STEEL MATERIAL AND DUPLEX STEEL TUBE |
CN116377321A (zh) * | 2023-03-24 | 2023-07-04 | 鞍钢股份有限公司 | 一种无铁素体的超纯净尿素级奥氏体不锈钢板及制备方法 |
Also Published As
Publication number | Publication date |
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EP2947169A1 (en) | 2015-11-25 |
CN104919072A (zh) | 2015-09-16 |
CN104919072B (zh) | 2017-07-14 |
KR20150087430A (ko) | 2015-07-29 |
US20150354038A1 (en) | 2015-12-10 |
KR101702252B1 (ko) | 2017-02-03 |
EP2947169A4 (en) | 2016-12-21 |
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