WO2018043565A1 - オーステナイト系ステンレス鋼 - Google Patents
オーステナイト系ステンレス鋼 Download PDFInfo
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- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
Definitions
- the present invention relates to stainless steel, and more particularly to austenitic stainless steel.
- Some are used in high temperature corrosive environments.
- air, moisture, and sulfide scale react to produce polythionic acid on the surface of the member.
- This polythionic acid induces stress corrosion cracking (hereinafter referred to as polythionic acid SCC) at grain boundaries. Therefore, the member used in the above-mentioned high temperature corrosive environment is required to have excellent polythionic acid SCC resistance.
- Patent Document 1 Japanese Patent Application Laid-Open No. 2003-166039
- Patent Document 2 International Publication No. 2009/044802
- the polythionic acid SCC is generated when Cr is precipitated as M 23 C 6 type carbide at the grain boundary and a Cr-deficient layer is formed in the vicinity of the grain boundary. Therefore, in Patent Document 1 and Patent Document 2, the amount of C is reduced to suppress the formation of M 23 C 6 type carbides, thereby improving the polythionic acid SCC resistance.
- the austenitic heat-resisting steel disclosed in Patent Document 1 is mass%, C: 0.005 to less than 0.03%, Si: 0.05 to 0.4%, Mn: 0.5 ⁇ 2%, P: 0.01 ⁇ 0.04%, S: 0.0005 ⁇ 0.005%, Cr: 18 ⁇ 20%, Ni: 7 ⁇ 11%, Nb: 0.2 ⁇ 0.5% V: 0.2 to 0.5%, Cu: 2 to 4%, N: 0.10 to 0.30%, B: 0.0005 to 0.0080%, the balance being Fe and inevitable Consists of impurities.
- the total content of Nb and V is 0.6% or more, and the amount of Nb solid solution in the steel is 0.15% or more.
- N / 14 ⁇ Nb / 93 + V / 51 and Cr-16C-0.5Nb-V ⁇ 17.5 are satisfied.
- the C content is reduced, and the relationship between Cr and C, Nb, and V is specified to improve the SCC resistance of polythionic acid.
- the austenitic stainless steel disclosed in Patent Document 2 is, by mass%, C: less than 0.04%, Si: 1.5% or less, Mn: 2% or less, Cr: 15 to 25%, Ni: 6 to 30%, N: 0.02 to 0.35%, Sol. Al: 0.03% or less, Nb: 0.5% or less, Ti: 0.4% or less, V: 0.4% or less, Ta: 0.2% or less, Hf: 0.2% One or more of Zr: 0.2% or less is contained below, and the balance consists of Fe and impurities.
- Patent Literature 1 and Patent Literature 2 although the purpose is to improve the SCC resistance of polythionic acid, it is not intended to improve the creep ductility.
- the C content is lowered in order to increase the SCC resistance of polythionic acid. In this case, high creep ductility may not be obtained.
- An object of the present invention is to provide an austenitic stainless steel having excellent polythionic acid SCC resistance and excellent creep ductility.
- the austenitic stainless steel according to the present invention is, in mass%, C: 0.030% or less, Si: 0.10 to 1.00%, Mn: 0.20 to 2.00%, P: 0.040% or less. S: 0.010% or less, Cr: 16.0 to 25.0%, Ni: 10.0 to 30.0%, Mo: 0.1 to 5.0%, Nb: 0.20 to 1. 00%, N: 0.050 to 0.300%, sol.
- the austenitic stainless steel according to the present invention has excellent polythionic acid SCC resistance and excellent creep ductility.
- the present inventors investigated and examined a steel excellent not only in polythionic acid SCC resistance but also in creep ductility.
- the present inventors further examined austenitic stainless steel that can achieve both excellent polythionic acid resistance SCC resistance and excellent creep ductility. It is considered that B (boron) segregates at the grain boundaries in the above-described high temperature corrosion environment of 600 to 700 ° C. and can increase the grain boundary strength.
- C 0.030% or less
- Si 0.10 to 1.00%
- Mn 0.20 to 2.00%
- P 0.040% or less
- S 0.010% or less
- Cr 16.0 to 25.0%
- Ni 10.0 to 30.0%
- Mo 0.1 to 5.0%
- Nb 0.20 to 1.00 %
- N 0.050 to 0.300%
- Al 0.0005 to 0.100%
- B 0.0010 to 0.0080%
- Cu 0 to 5.0%
- W 0 to 5.0%
- Co 0 to 1.0%
- V 0 to 1.00%
- Ta 0 to 0.2%
- Hf 0 to 0.20%
- Ca 0 to 0.010%
- Mg 0 to 0.010%
- rare earth elements 0
- An austenitic stainless steel containing ⁇ 0.10% and the balance being Fe and impurities was considered to be able to achieve both excellent polythionic acid SCC resistance and excellent creep ductility.
- the C content is 0.030% or less, but also C containing 0.20 to 1.00% Nb. Fix to Nb to reduce solute C.
- Nb is combined with C and precipitated as MX-type carbonitride by solution treatment or aging in a short time.
- MX type carbonitride is a metastable phase in the environment of using the steel material of the present embodiment (high temperature corrosion environment of 600 to 700 ° C.).
- the MX type carbonitride of Nb becomes a Z phase (CrNbN) and M 23 C 6 type carbide which are stable phases. Change.
- the B that segregates at the grain boundaries is replaced with a portion of the C of M 23 C 6 type carbide is absorbed by the M 23 C 6 type carbide. Therefore, the amount of B segregated at the grain boundary is reduced, and the grain boundary strength is lowered. As a result, it is considered that sufficient creep ductility cannot be obtained.
- Mo suppresses the formation itself of M 23 C 6 type carbide.
- Mo is further replaced with a part of M of M 23 C 6 type carbide, which may be dissolved in M 23 C 6 type carbide.
- the M 23 C 6 type carbide in which Mo is dissolved is defined as “Mo solid solution M 23 C 6 type carbide”.
- Mo solid solution M 23 C 6 type carbide is difficult to dissolve B. Therefore, even when the MX type carbonitride containing Nb is changed to the Z phase and M 23 C 6 type carbide during use in a high temperature corrosive environment, the M 23 C 6 type carbide is dissolved in Mo.
- the MX type carbonitride containing Nb changed to the Z phase and the M 23 C 6 type carbide during use in a high temperature corrosion environment of 600 to 700 ° C.
- the chemical composition capable of suppressing the reduction of the amount of segregation B at the grain boundaries was further examined by the formation of Mo solid solution M 23 C 6 type carbide.
- B, C, and Mo in the chemical composition are closely related to the suppression of the reduction in the amount of segregated B due to the generation of Mo solid solution M 23 C 6 type carbide.
- the creep ductility is further increased.
- the reason for this is not clear, but the following can be considered.
- Mo is further segregated at the grain boundary during use in a high temperature corrosion environment of 600 to 700 ° C. Or produce intermetallic compounds. This grain boundary segregation or intermetallic compound further increases the grain boundary strength.
- creep ductility is further increased. Therefore, the preferable lower limit of the Mo content is 0.5%.
- the lower limit of the preferable Mo content for further increasing the creep ductility is 0.8%, more preferably 1.0%, and further preferably 2.0%.
- the austenitic stainless steel according to the present invention completed based on the above knowledge is, in mass%, C: 0.030% or less, Si: 0.10 to 1.00%, Mn: 0.20 to 2.00%. P: 0.040% or less, S: 0.010% or less, Cr: 16.0-25.0%, Ni: 10.0-30.0%, Mo: 0.1-5.0% Nb: 0.20 to 1.00%, N: 0.050 to 0.300%, sol.
- Al 0.0005 to 0.1000%
- B 0.0010 to 0.0080%
- Cu 0 to 5.0%
- W 0 to 5.0%
- Co 0 to 1.0%
- V 0 to 1.00%
- Ta 0 to 0.2%
- Hf 0 to 0.20%
- Ca 0 to 0.010%
- Mg 0 to 0.010%
- rare earth elements 0 It contains ⁇ 0.10%, the balance is Fe and impurities, and has a chemical composition satisfying the formula (1).
- the content (mass%) of the corresponding element is substituted for each element symbol of the formula (1).
- the chemical composition is selected from the group consisting of Cu: 0.1 to 5.0%, W: 0.1 to 5.0%, and Co: 0.1 to 1.0% by mass%. You may contain a seed or two or more sorts.
- the chemical composition is selected from the group consisting of V: 0.1 to 1.00%, Ta: 0.01 to 0.2%, and Hf: 0.01 to 0.20% by mass%. You may contain a seed or two or more sorts.
- the chemical composition is selected from the group consisting of Ca: 0.0005 to 0.010%, Mg: 0.0005 to 0.010%, and rare earth elements: 0.001 to 0.10% by mass. 1 type (s) or 2 or more types may be contained.
- the above chemical composition may contain Cu: 0 to 1.9% by mass.
- the above chemical composition may contain Mo: 0.5 to 5.0% by mass.
- the chemical composition of the austenitic stainless steel of this embodiment contains the following elements.
- C 0.030% or less Carbon (C) is unavoidably contained.
- C produces M 23 C 6 type carbides at the grain boundaries while using the austenitic stainless steel of the present embodiment in a high temperature corrosive environment of 600 to 700 ° C., and lowers the polythionic acid SCC resistance. Therefore, the C content is 0.030% or less.
- the upper limit with preferable C content is 0.020%, More preferably, it is 0.015%.
- the C content is preferably as low as possible. However, as described above, since C is inevitably contained, at least 0.0001% of C can be contained in industrial production. Therefore, the preferable lower limit of the C content is 0.0001%.
- Si 0.10 to 1.00% Silicon (Si) deoxidizes steel. Si further increases the oxidation resistance and steam oxidation resistance of the steel. If the Si content is too low, the above effect cannot be obtained. On the other hand, if the Si content is too high, a sigma phase ( ⁇ phase) is precipitated in the steel, and the toughness of the steel is reduced. Therefore, the Si content is 0.10 to 1.00%.
- the upper limit with preferable Si content is 0.75%, More preferably, it is 0.50%.
- Mn 0.20 to 2.00%
- Manganese (Mn) deoxidizes steel. Mn further stabilizes austenite and increases creep strength. If the Mn content is too low, the above effect cannot be obtained. On the other hand, if the Mn content is too high, the creep strength of the steel decreases. Therefore, the Mn content is 0.20 to 2.00%.
- the minimum with preferable Mn content is 0.40%, More preferably, it is 0.50%.
- the upper limit with preferable Mn content is 1.70%, More preferably, it is 1.50%.
- Phosphorus (P) is an impurity. P decreases the hot workability and toughness of the steel. Therefore, the P content is 0.040% or less.
- the upper limit with preferable P content is 0.035%, More preferably, it is 0.032%.
- the P content is preferably as low as possible. However, P is unavoidably contained, and P may be contained at least 0.0001% in industrial production. Therefore, the preferable lower limit of the P content is 0.0001%.
- S 0.010% or less Sulfur (S) is an impurity. S decreases the hot workability and creep ductility of the steel. Therefore, the S content is 0.010% or less.
- the upper limit with preferable S content is 0.005%.
- the S content is preferably as low as possible. However, S is unavoidably contained, and at least 0.0001% of S can be contained in industrial production. Therefore, the preferable lower limit of the S content is 0.0001%.
- Chromium (Cr) improves the SCC resistance of the steel. Cr further enhances oxidation resistance, steam oxidation resistance, high temperature corrosion resistance, and the like. If the Cr content is too low, the above effect cannot be obtained. On the other hand, if the Cr content is too high, the creep strength and toughness of the steel decrease. Therefore, the Cr content is 16.0 to 25.0%. The minimum with preferable Cr content is 16.5%, More preferably, it is 17.0%. The upper limit with preferable Cr content is 24.0%, More preferably, it is 23.0%.
- Ni 10.0-30.0%
- Nickel (Ni) stabilizes austenite and increases creep strength. If the Ni content is too low, the above effect cannot be obtained. On the other hand, if the Ni content is too high, the above effects are saturated and the manufacturing cost is increased. Therefore, the Ni content is 10.0 to 30.0%.
- the minimum with preferable Ni content is 11.0%, More preferably, it is 13.0%.
- the upper limit with preferable Ni content is 25.0%, More preferably, it is 22.0%.
- Mo 0.1-5.0% Molybdenum (Mo) suppresses the formation of M 23 C 6 type carbides at grain boundaries during use in a high temperature corrosion environment of 600 to 700 ° C. Mo is further during use under high temperature corrosive environment at 600 ⁇ 700 ° C., when the MX type carbonitrides of Nb is changed to M 23 C 6 type carbide, B is a solid solution in the M 23 C 6 type carbide To suppress the reduction of the amount of segregation B at the grain boundary in a high temperature corrosive environment. Thereby, sufficient creep ductility is obtained in a high temperature corrosive environment. If the Mo content is too low, the above effect cannot be obtained. On the other hand, if the Mo content is too high, the stability of austenite decreases. Therefore, the Mo content is 0.1 to 5.0%. The minimum with preferable Mo content is 0.2%, More preferably, it is 0.3%.
- Mo Mo further segregates at the grain boundary or generates an intermetallic compound to further increase the grain boundary strength. In this case, even better creep strength can be obtained in a high temperature corrosive environment. Therefore, a more preferable lower limit of the Mo content is 0.5%, more preferably 0.8%, further preferably 1.0%, further preferably 1.5%, and more preferably 2.0%. If the Mo content is 1.5% or more, the creep strength is also increased. The upper limit with preferable Mo content is 4.5%, More preferably, it is 4.0%. If the Mo content is 1.5% or more, the creep strength is also increased.
- Niobium (Nb) combines with C to form MX-type carbonitride during use in a hot corrosive environment of 600 to 700 ° C., and reduces the amount of solute C in the steel. Thereby, the polythionic acid SCC resistance of steel increases.
- the produced Nb MX carbonitride also increases the creep strength. If the Nb content is too low, the above effect cannot be obtained. On the other hand, if the Nb content is too high, ⁇ ferrite is generated and the long-time creep strength, toughness, and weldability of the steel are reduced. Therefore, the Nb content is 0.20 to 1.00%.
- the minimum with preferable Nb content is 0.25%.
- the upper limit with preferable Nb content is 0.90%, More preferably, it is 0.80%.
- N 0.050 to 0.300% Nitrogen (N) is dissolved in the matrix (matrix) to stabilize austenite and increase the creep strength. N further forms fine carbonitrides in the grains and increases the creep strength of the steel. That is, N contributes to the creep strength in both solid solution strengthening and precipitation strengthening. If the N content is too low, the above effect cannot be obtained. On the other hand, if the N content is too high, Cr nitride is formed at the grain boundaries, and the polythionic acid SCC resistance at the weld heat affected zone (HAZ) is lowered. If the N content is too high, the workability of the steel further decreases. Therefore, the N content is 0.050 to 0.300%. The minimum with preferable N content is 0.070%. The upper limit with preferable N content is 0.250%, More preferably, it is 0.200%.
- Al 0.0005 to 0.100%
- Aluminum (Al) deoxidizes steel. If the Al content is too low, the above effect cannot be obtained. On the other hand, if the Al content is too high, the cleanliness of the steel is lowered, and the workability and ductility of the steel are lowered. Therefore, the Al content is 0.0005 to 0.100%.
- the minimum with preferable Al content is 0.001%, More preferably, it is 0.002%.
- the upper limit with preferable Al content is 0.050%, More preferably, it is 0.030%.
- Al content means content of acid-soluble Al (sol.Al).
- B 0.0010 to 0.0080% Boron (B) segregates at the grain boundary during use in a high temperature corrosive environment at 600 to 700 ° C., and increases the grain boundary strength. As a result, the creep ductility is increased. If the B content is too low, the above effect cannot be obtained. On the other hand, if the B content is too high, weldability and hot workability at high temperatures are reduced. Therefore, the B content is 0.0010 to 0.0080%.
- the minimum with preferable B content is 0.0015%, More preferably, it is 0.0020%.
- the upper limit with preferable B content is less than 0.0060%, More preferably, it is 0.0050%.
- the balance of the chemical composition of the austenitic stainless steel according to the present embodiment is composed of Fe and impurities.
- the impurities are mixed from ore, scrap, or production environment as raw materials when industrially producing austenitic stainless steel, and adversely affect the austenitic stainless steel of the present embodiment. It means that it is allowed in the range that does not give.
- the austenitic stainless steel according to the present embodiment may further contain one or more selected from the group consisting of Cu, W and Co instead of a part of Fe. All of these elements increase the creep strength of the steel.
- Cu 0 to 5.0% Copper (Cu) is an optional element and may not be contained. When contained, Cu precipitates as a Cu phase in the grains during use in a high temperature corrosive environment of 600 to 700 ° C., and increases the creep strength of the steel by precipitation strengthening. However, if the Cu content is too high, the hot workability and weldability of the steel deteriorate. Therefore, the Cu content is 0 to 5.0%.
- a preferable lower limit of the Cu content for further effectively increasing the creep strength is 0.1%, more preferably 2.0%, and further preferably 2.5%.
- the upper limit with preferable Cu content is 4.5%, More preferably, it is 4.0%.
- the preferable Cu content for maintaining better creep ductility is 0 to 1.9%, and the more preferable upper limit of Cu content is 1.8%.
- W 0-5.0% Tungsten (W) is an optional element and may not be contained. When contained, W dissolves in the matrix (matrix) and increases the creep strength of the steel. However, if the W content is too high, the stability of austenite decreases, and the creep strength and toughness of the steel decrease. Therefore, the W content is 0 to 5.0%.
- the minimum with preferable W content is 0.1%, More preferably, it is 0.2%.
- the upper limit with preferable W content is 4.5%, More preferably, it is 4.0%.
- Co 0 to 1.0%
- Cobalt (Co) is an optional element and may not be contained. When contained, Co stabilizes austenite and increases creep strength. However, if the Co content is too high, the raw material cost increases. Therefore, the Co content is 0 to 1.0%.
- the minimum with preferable Co content is 0.1%, More preferably, it is 0.2%.
- the austenitic stainless steel according to the present embodiment may further contain one or more selected from the group consisting of V, Ta, and Hf instead of part of Fe. All of these elements increase the SCC resistance and creep strength of the steel.
- V 0 to 1.00%
- Vanadium (V) is an optional element and may not be contained. When contained, V combines with C to form carbonitride during use in a hot corrosive environment of 600 to 700 ° C., thereby reducing solid solution C, and resistance to polythionate SCC of steel. To increase. The produced V carbonitride also increases the creep strength. However, if the V content is too high, ⁇ ferrite is generated, and the creep strength, toughness, and weldability of the steel are reduced. Therefore, the V content is 0 to 1.00%.
- the preferable lower limit of the V content for further effectively increasing the polythionic acid SCC resistance and the creep strength is 0.10%.
- the upper limit with preferable V content is 0.90%, More preferably, it is 0.80%.
- Tantalum (Ta) is an optional element and may not be contained. When contained, Ta combines with C to form carbonitride during use in a hot corrosive environment of 600 to 700 ° C., thereby reducing solid solution C, and resistance to polythionate SCC of steel. To increase. The produced Ta carbonitride also increases the creep strength. However, if the Ta content is too high, ⁇ ferrite is generated, and the creep strength, toughness, and weldability of the steel are reduced. Therefore, the Ta content is 0 to 0.2%. A preferable lower limit of the Ta content for further effectively increasing the SCC resistance and creep strength of the polythionic acid is 0.01%, and more preferably 0.02%.
- Hf 0 to 0.20%
- Hafnium (Hf) is an optional element and may not be contained. When contained, Hf combines with C to form carbonitride during use in a hot corrosive environment of 600 to 700 ° C., thereby reducing solid solution C and reducing the resistance of the steel to polythionate SCC. To increase. The produced Hf carbonitride also increases creep strength. However, if the Hf content is too high, ⁇ ferrite is generated, and the creep strength, toughness, and weldability of the steel are reduced. Therefore, the Hf content is 0 to 0.20%. The minimum with preferable Hf content is 0.01%, More preferably, it is 0.02%.
- the austenitic stainless steel according to the present embodiment may further contain one or more selected from the group consisting of Ca, Mg and rare earth elements instead of a part of Fe. All of these elements enhance the hot workability and creep ductility of the steel.
- Ca 0 to 0.010%
- Calcium (Ca) is an optional element and may not be contained. When contained, Ca fixes O (oxygen) and S (sulfur) as inclusions, and improves the hot workability and creep ductility of the steel. However, if the Ca content is too high, the hot workability and creep ductility of the steel are reduced. Therefore, the Ca content is 0 to 0.010%.
- the minimum with preferable Ca content is 0.0005%, More preferably, it is 0.001%.
- the upper limit with preferable Ca content is 0.008%, More preferably, it is 0.006%.
- Mg 0 to 0.010%
- Magnesium (Mg) is an optional element and may not be contained. When contained, Mg fixes O (oxygen) and S (sulfur) as inclusions, and improves the hot workability and creep ductility of the steel. However, if the Mg content is too high, the hot workability and long-term creep ductility of the steel are reduced. Therefore, the Mg content is 0 to 0.010%.
- the minimum with preferable Mg content is 0.0005%, More preferably, it is 0.001%.
- the upper limit with preferable Mg content is 0.008%, More preferably, it is 0.006%.
- the rare earth element is an optional element and may not be contained. When contained, REM fixes O (oxygen) and S (sulfur) as inclusions, and improves the hot workability and creep ductility of the steel. However, if the REM content is too high, the hot workability and long-term creep ductility of the steel are reduced. Therefore, the REM content is 0 to 0.01%.
- the minimum with preferable REM content is 0.001%, More preferably, it is 0.002%.
- the upper limit with preferable REM content is 0.08%, More preferably, it is 0.06%.
- REM in the present specification contains at least one of Sc, Y, and lanthanoid (La of atomic number 57 to Lu of 71), and the REM content means the total content of these elements To do.
- Nb MX-type carbonitride in order to increase the SCC resistance of polythionic acid, not only the C content is 0.030% or less, but also 0.20 to 1.00% Nb is contained, and 600 Nb MX-type carbonitride is produced during use in a high-temperature corrosive environment of ⁇ 700 ° C., and the amount of dissolved C is reduced.
- Nb MX type carbonitride since Nb MX type carbonitride is a metastable phase, it changes to Z phase and M 23 C 6 type carbide during use in the high temperature use environment. At this time, B segregated at the grain boundaries is dissolved in the M 23 C 6 type carbide and the amount of B segregation at the grain boundaries is reduced. As a result, creep ductility is reduced.
- Mo is generating a "Mo solid solution M 23 C 6 type carbides" a solid solution in the M 23 type C 6 type carbide, the Mo solid solution M 23 C 6 type carbides B is hardly dissolved. Therefore, the amount of B segregation at the grain boundary is maintained, and not only excellent polythionic acid SCC resistance is obtained, but also excellent creep ductility is obtained.
- F1 B + 0.004-0.9C + 0.017Mo 2 .
- F1 is an index indicating a ratio of Mo solid solution M 23 C 6 type carbide among a plurality of M 23 C 6 type carbide generated in steel in use in a high temperature corrosive environment. If F1 is 0 or more, even if a plurality of M 23 C 6 type carbides are produced in steel during use in a high temperature corrosive environment, the ratio of Mo solid solution M 23 C 6 type carbides is high. Therefore, B segregated at the grain boundary is hardly dissolved in the M 23 C 6 type carbide, and the amount of segregated B at the grain boundary is maintained.
- F1 is 0 (0.00000) or more.
- F1 is 0.00100 or more, more preferably 0.00200 or more, further preferably 0.00400 or more, more preferably 0.00500, and further preferably 0.00800 or more. And most preferably 0.01000.
- the upper limit of the Cu content is 1.9% or less. That is, considering the fact that the creep strength is increased while obtaining excellent creep ductility, the preferable Cu content is 0% to 1.9%. When the Cu content is 1.9% or less, excellent creep ductility can be maintained while obtaining excellent creep strength by precipitation strengthening of the Cu phase.
- the lower limit of the Mo content is preferably 0.5%.
- Mo further segregates at the grain boundary or generates an intermetallic compound. This grain boundary segregation or intermetallic compound further increases the grain boundary strength. As a result, creep ductility is further increased. Therefore, the preferable lower limit of the Mo content is 1.0%.
- preferable F1 value is 0.00500 or more, More preferably, it is 0.00800 or more, More preferably, it is 0.01000 or more.
- This manufacturing method includes a preparation process for preparing a raw material, a hot working process for manufacturing a steel material by performing hot working on the raw material, and cold-working the steel material after the hot working process as necessary.
- a cold working process and the solution treatment process which performs a solution treatment with respect to steel materials as needed are provided.
- the manufacturing method will be described.
- a molten steel having the above-described chemical composition and satisfying the formula (1) is manufactured.
- the molten steel is produced by using an electric furnace, an AOD (Argon Oxygen Decarburization) furnace, or a VOD (Vacuum Oxygen Decarburization) furnace.
- a well-known degassing process is implemented with respect to the manufactured molten steel as needed.
- the material is manufactured from the molten steel that has been degassed.
- the material manufacturing method is, for example, a continuous casting method.
- a continuous casting material (material) is manufactured by a continuous casting method.
- the continuous cast material is, for example, a slab, bloom, billet and the like.
- Molten steel may be made into an ingot by the ingot-making method.
- the prepared material (continuous cast material or ingot) is hot-worked to produce an austenitic stainless steel material.
- a raw material is hot-rolled to produce a steel plate, a steel bar, or a wire.
- an austenitic stainless steel pipe is manufactured by hot extrusion, hot piercing and rolling.
- a specific method of hot working is not particularly limited, and hot working corresponding to the shape of the final product may be performed.
- the processing end temperature of the hot processing is, for example, 1050 ° C. or higher.
- the processing end temperature here means the temperature of the steel material immediately after the final hot processing is completed.
- cold working may be performed on the austenitic stainless steel material after hot working.
- the austenitic stainless steel material is a steel bar, a wire, or a steel pipe
- the cold working is, for example, cold drawing or cold rolling.
- the austenitic stainless steel material is a steel plate, cold rolling or the like is performed.
- solution treatment process After hot working or after cold working, solution treatment may be performed as necessary.
- the structure is homogenized and the carbonitride is solid-dissolved.
- the preferred solution treatment temperature is as follows.
- Preferred solution treatment temperature 1000 to 1250 ° C. If the solution treatment temperature is 1000 ° C. or higher, the Nb carbonitride is sufficiently dissolved, and the creep strength is further increased. If heat processing temperature is 1250 degrees C or less, the excessive solid solution of C can be suppressed and polythionic acid SCC resistance will further improve.
- the holding time at the solution treatment temperature at the time of the solution treatment is not particularly limited, but is, for example, 2 to 60 minutes.
- the processing end temperature of the hot processing is 1000 ° C. or higher.
- the hot working finish temperature is 1000 ° C. or higher, the Nb carbonitride is sufficiently dissolved, and has excellent polythionic acid SCC resistance and excellent creep when used in a high temperature corrosive environment of 600 to 700 ° C. It is possible to achieve both ductility, and sufficient creep strength can be obtained by the formation of Nb carbonitride during use in a high temperature environment.
- the austenitic stainless steel of this embodiment is not specifically limited.
- the austenitic stainless steel of the present embodiment may be a steel plate, a steel pipe, a bar or wire, or a shape steel.
- the thickness of the manufactured austenitic stainless steel sheet is defined as t (mm), and a well-known component analysis method (combustion-infrared for C and S is used for samples at an arbitrary position at a depth of t / 4 from the surface.
- the absorption method, the high temperature desorption gas analysis method for N, and the ICP analysis method for other alloy elements were performed.
- the chemical composition of the austenitic stainless steel sheet of each test number was consistent with Table 1.
- a U-bend type test piece was immersed in a Wackerroder solution (a solution in which a large amount of H 2 S gas was blown into a saturated aqueous solution of H 2 SO 3 prepared by blowing SO 2 gas into distilled water) at room temperature for 100 hours. With respect to the test piece after immersion, the presence or absence of cracks was observed with a microscope at a magnification of 500 times to confirm the presence or absence of cracks.
- Wackerroder solution a solution in which a large amount of H 2 S gas was blown into a saturated aqueous solution of H 2 SO 3 prepared by blowing SO 2 gas into distilled water
- a creep rupture test piece in accordance with JIS Z2271 (2010) was produced from the steel plate of each test number.
- the cross section perpendicular to the axial direction of the creep rupture test piece was circular, the outer diameter of the creep rupture test piece was 6 mm, and the parallel part was 30 mm.
- the parallel part was parallel to the rolling direction of the steel sheet.
- a creep rupture test based on JIS Z2271 (2010) was performed using the prepared creep rupture test piece. Specifically, the creep rupture test was performed after heating the creep rupture test piece at 750 ° C. The test stress was 45 MPa, and the creep rupture time (hours) and the creep rupture drawing (%) were determined.
- test numbers 3 and 4 which contain Cu content 1.9% or less and contain Mo 0.5% or more, and the test number which contains Mo 1.0% or more even if it does not contain Cu In Nos. 5 to 7, 11, and 12, sufficient creep strength was obtained, and excellent creep ductility was also obtained.
- test number 19 the C content was too high. As a result, the SCC resistance of polythionic acid was low.
- Test No. 21 contained no Mo. Furthermore, F1 was less than the lower limit of formula (1). As a result, the fracture drawing was less than 20.0%, and the creep ductility of the steel was low. The creep strength was also low.
- test number 22 the B content was low. As a result, the creep rupture drawing was less than 20.0%, and the creep ductility of the steel was low. The creep strength was also low.
- Test No. 23 did not contain Nb. As a result, the SCC resistance of polythionic acid was low. Furthermore, the rupture time was less than 5000 hours, and the creep strength of the steel was low.
Abstract
Description
B+0.004-0.9C+0.017Mo2≧0 (1)
ここで、式(1)の各元素記号には、対応する元素の含有量(質量%)が代入される。
B+0.004-0.9C+0.017Mo2≧0 (1)
ここで、式(1)の各元素記号には、対応する元素の含有量(質量%)が代入される。
B+0.004-0.9C+0.017Mo2≧0 (1)
ここで、式(1)の各元素記号には、対応する元素の含有量(質量%)が代入される。
本実施形態のオーステナイト系ステンレス鋼の化学組成は、次の元素を含有する。
炭素(C)は不可避に含有される。Cは、600~700℃の高温腐食環境下で本実施形態のオーステナイト系ステンレス鋼を使用中において、粒界にM23C6型炭化物を生成し、耐ポリチオン酸SCC性を低下する。したがって、C含有量は0.030%以下である。C含有量の好ましい上限は0.020%であり、さらに好ましくは0.015%である。C含有量はなるべく低い方が好ましい。しかしながら、上述のとおり、Cは不可避に含有されるため、工業生産上、Cは少なくとも、0.0001%は含有され得る。そのため、C含有量の好ましい下限値は0.0001%である。
シリコン(Si)は、鋼を脱酸する。Siはさらに、鋼の耐酸化性及び耐水蒸気酸化性を高める。Si含有量が低すぎれば、上記効果が得られない。一方、Si含有量が高すぎれば、鋼中にシグマ相(σ相)が析出し、鋼の靭性が低下する。したがって、Si含有量は0.10~1.00%である。Si含有量の好ましい上限は0.75%であり、さらに好ましくは0.50%である。
マンガン(Mn)は鋼を脱酸する。Mnはさらに、オーステナイトを安定化して、クリープ強度を高める。Mn含有量が低すぎれば、上記効果が得られない。一方、Mn含有量が高すぎれば、鋼のクリープ強度が低下する。したがって、Mn含有量は0.20~2.00%である。Mn含有量の好ましい下限は0.40%であり、さらに好ましくは0.50%である。Mn含有量の好ましい上限は1.70%であり、さらに好ましくは1.50%である。
燐(P)は不純物である。Pは鋼の熱間加工性及び靭性を低下する。したがって、P含有量は0.040%以下である。P含有量の好ましい上限は0.035%であり、さらに好ましくは0.032%である。P含有量はなるべく低い方が好ましい。しかしながら、Pは不可避に含有され、工業生産上、Pは少なくとも、0.0001%は含有され得る。そのため、P含有量の好ましい下限値は0.0001%である。
硫黄(S)は不純物である。Sは鋼の熱間加工性及びクリープ延性を低下する。したがって、S含有量は0.010%以下である。S含有量の好ましい上限は0.005%である。S含有量はなるべく低い方が好ましい。しかしながら、Sは不可避に含有され、工業生産上、Sは少なくとも、0.0001%は含有され得る。そのため、S含有量の好ましい下限値は0.0001%である。
クロム(Cr)は鋼の耐ポリチオン酸SCC性を高める。Crはさらに、耐酸化性、耐水蒸気酸化性、耐高温腐食性等を高める。Cr含有量が低すぎれば、上記効果が得られない。一方、Cr含有量が高すぎれば、鋼のクリープ強度及び靭性が低下する。したがって、Cr含有量は16.0~25.0%である。Cr含有量の好ましい下限は16.5%であり、さらに好ましくは17.0%である。Cr含有量の好ましい上限は24.0%であり、さらに好ましくは23.0%である。
ニッケル(Ni)はオーステナイトを安定化して、クリープ強度を高める。Ni含有量が低すぎれば、上記効果が得られない。一方、Ni含有量が高すぎれば、上記効果が飽和し、さらに、製造コストが高くなる。したがって、Ni含有量は10.0~30.0%である。Ni含有量の好ましい下限は11.0%であり、さらに好ましくは13.0%である。Ni含有量の好ましい上限は25.0%であり、さらに好ましくは22.0%である。
モリブデン(Mo)は、600~700℃の高温腐食環境下での使用中において、粒界にM23C6型炭化物が生成するのを抑制する。Moはさらに、600~700℃での高温腐食環境下での使用中において、NbのMX型炭窒化物がM23C6型炭化物に変化するとき、M23C6型炭化物にBが固溶するのを抑制して、高温腐食環境下での粒界の偏析B量が低減するのを抑制する。これにより、高温腐食環境下において、十分なクリープ延性が得られる。Mo含有量が低すぎれば、上記効果が得られない。一方、Mo含有量が高すぎれば、オーステナイトの安定性が低下する。したがって、Mo含有量は0.1~5.0%である。Mo含有量の好ましい下限は0.2%であり、さらに好ましくは0.3%である。
ニオブ(Nb)は、600~700℃の高温腐食環境下での使用中において、Cと結合してMX型炭窒化物を生成し、鋼中の固溶C量を低減する。これにより、鋼の耐ポリチオン酸SCC性が高まる。生成したNbのMX型炭窒化物はまた、クリープ強度を高める。Nb含有量が低すぎれば、上記効果が得られない。一方、Nb含有量が高すぎれば、δフェライトが生成し、鋼の長時間クリープ強度、靭性、及び、溶接性を低下する。したがって、Nb含有量は0.20~1.00%である。Nb含有量の好ましい下限は0.25%である。Nb含有量の好ましい上限は0.90%であり、さらに好ましくは0.80%である。
窒素(N)はマトリクス(母相)に固溶してオーステナイトを安定化して、クリープ強度を高める。Nはさらに、粒内に微細な炭窒化物を形成し、鋼のクリープ強度を高める。つまり、Nは、固溶強化及び析出強化の両方でクリープ強度に寄与する。N含有量が低すぎれば、上記効果が得られない。一方、N含有量が高すぎれば、粒界でCr窒化物が形成され、溶接熱影響部(HAZ)での耐ポリチオン酸SCC性が低下する。N含有量が高すぎればさらに、鋼の加工性が低下する。したがって、N含有量は0.050~0.300%である。N含有量の好ましい下限は0.070%である。N含有量の好ましい上限は0.250%であり、さらに好ましくは0.200%である。
アルミニウム(Al)は鋼を脱酸する。Al含有量が低すぎれば、上記効果が得られない。一方、Al含有量が高すぎれば、鋼の清浄度が低下し、鋼の加工性及び延性が低下する。したがって、Al含有量は0.0005~0.100%である。Al含有量の好ましい下限は0.001%であり、さらに好ましくは0.002%である。Al含有量の好ましい上限は0.050%であり、さらに好ましくは0.030%である。本実施形態においてAl含有量は、酸可溶Al(sol.Al)の含有量を意味する。
ボロン(B)は、600~700℃での高温腐食環境下での使用中において、粒界に偏析し、粒界強度を高める。その結果、クリープ延性を高める。B含有量が低すぎれば、上記効果が得られない。一方、B含有量が高すぎれば、溶接性及び高温での熱間加工性が低下する。したがって、B含有量は0.0010~0.0080%である。B含有量の好ましい下限は、0.0015%であり、さらに好ましくは0.0020%である。B含有量の好ましい上限は0.0060%未満であり、さらに好ましくは0.0050%である。
本実施形態によるオーステナイト系ステンレス鋼はさらに、Feの一部に代えて、Cu、W及びCoからなる群から選択される1種又は2種以上を含有してもよい。これらの元素はいずれも、鋼のクリープ強度を高める。
銅(Cu)は任意元素であり、含有されなくてもよい。含有される場合、Cuは600~700℃の高温腐食環境での使用中において、粒内にCu相として析出して、析出強化により鋼のクリープ強度を高める。しかしながら、Cu含有量が高すぎれば、鋼の熱間加工性及び溶接性が低下する。したがって、Cu含有量は0~5.0%である。クリープ強度をさらに有効に高めるためのCu含有量の好ましい下限は0.1%であり、さらに好ましくは2.0%であり、さらに好ましくは2.5%である。Cu含有量の好ましい上限は4.5%であり、さらに好ましくは4.0%である。一方、より優れたクリープ延性を維持するための好ましいCu含有量は0~1.9%であり、さらに好ましくいCu含有量の上限は、1.8%である。
タングステン(W)は任意元素であり、含有されなくてもよい。含有される場合、Wはマトリクス(母相)に固溶して、鋼のクリープ強度を高める。しかしながら、W含有量が高すぎれば、オーステナイトの安定性が低下し、鋼のクリープ強度や靭性が低下する。したがって、W含有量は0~5.0%である。W含有量の好ましい下限は0.1%であり、さらに好ましくは0.2%である。W含有量の好ましい上限は4.5%であり、さらに好ましくは4.0%である。
コバルト(Co)は任意元素であり、含有されなくてもよい。含有される場合、Coはオーステナイトを安定化して、クリープ強度を高める。しかしながら、Co含有量が高すぎれば、原料コストが高まる。したがって、Co含有量は0~1.0%である。Co含有量の好ましい下限は0.1%であり、さらに好ましくは0.2%である。
バナジウム(V)は任意元素であり、含有されなくてもよい。含有される場合、Vは、600~700℃の高温腐食環境下での使用中において、Cと結合して炭窒化物を生成して、固溶Cを低減し、鋼の耐ポリチオン酸SCC性を高める。生成したV炭窒化物はまた、クリープ強度を高める。しかしながら、V含有量が高すぎれば、δフェライトが生成し、鋼のクリープ強度、靭性、及び溶接性が低下する。したがって、V含有量は0~1.00%である。耐ポリチオン酸SCC性及びクリープ強度をさらに有効に高めるためのV含有量の好ましい下限は0.10%である。V含有量の好ましい上限は0.90%であり、さらに好ましくは0.80%である。
タンタル(Ta)は任意元素であり、含有されなくてもよい。含有される場合、Taは、600~700℃の高温腐食環境下での使用中において、Cと結合して炭窒化物を生成して、固溶Cを低減し、鋼の耐ポリチオン酸SCC性を高める。生成したTa炭窒化物はまた、クリープ強度を高める。しかしながら、Ta含有量が高すぎれば、δフェライトが生成し、鋼のクリープ強度、靭性、及び溶接性が低下する。したがって、Ta含有量は0~0.2%である。耐ポリチオン酸SCC性及びクリープ強度をさらに有効に高めるためのTa含有量の好ましい下限は0.01%であり、さらに好ましくは0.02%である。
ハフニウム(Hf)は任意元素であり、含有されなくてもよい。含有される場合、Hfは、600~700℃の高温腐食環境下での使用中において、Cと結合して炭窒化物を生成して、固溶Cを低減し、鋼の耐ポリチオン酸SCC性を高める。生成したHf炭窒化物はまた、クリープ強度を高める。しかしながら、Hf含有量が高すぎれば、δフェライトが生成し、鋼のクリープ強度、靭性、及び溶接性が低下する。したがって、Hf含有量は0~0.20%である。Hf含有量の好ましい下限は0.01%であり、さらに好ましくは0.02%である。
カルシウム(Ca)は任意元素であり、含有されなくてもよい。含有される場合、Caは、O(酸素)及びS(硫黄)を介在物として固定し、鋼の熱間加工性及びクリープ延性を高める。しかしながら、Ca含有量が高すぎれば、鋼の熱間加工性及びクリープ延性を低下する。したがって、Ca含有量は0~0.010%である。Ca含有量の好ましい下限は0.0005%であり、さらに好ましくは0.001%である。Ca含有量の好ましい上限は0.008%であり、さらに好ましくは0.006%である。
マグネシウム(Mg)は任意元素であり、含有されなくてもよい。含有される場合、Mgは、O(酸素)及びS(硫黄)を介在物として固定し、鋼の熱間加工性及びクリープ延性を高める。しかしながら、Mg含有量が高すぎれば、鋼の熱間加工性及び長時間クリープ延性を低下する。したがって、Mg含有量は0~0.010%である。Mg含有量の好ましい下限は0.0005%であり、さらに好ましくは0.001%である。Mg含有量の好ましい上限は0.008%であり、さらに好ましくは0.006%である。
希土類元素(REM)は任意元素であり、含有されなくてもよい。含有される場合、REMは、O(酸素)及びS(硫黄)を介在物として固定し、鋼の熱間加工性及びクリープ延性を高める。しかしながら、REM含有量が高すぎれば、鋼の熱間加工性及び長時間クリープ延性を低下する。したがって、REM含有量は0~0.01%である。REM含有量の好ましい下限は0.001%であり、さらに好ましくは0.002%である。REM含有量の好ましい上限は0.08%であり、さらに好ましくは0.06%である。
上記化学組成はさらに、式(1)を満たす。
B+0.004-0.9C+0.017Mo2≧0 (1)
式(1)中の各元素記号には、対応する元素の含有量(質量%)が代入される。
本発明のオーステナイト系ステンレス鋼の製造方法の一例を説明する。本製造方法は、素材を準備する準備工程と、素材に対して熱間加工を実施して鋼材を製造する熱間加工工程と、必要に応じて熱間加工工程後の鋼材を冷間加工する冷間加工工程と、必要に応じて鋼材に対して溶体化処理を実施する溶体化処理工程とを備える。以下、製造方法について説明する。
上述の化学組成であって、式(1)を満たす溶鋼を製造する。たとえば、電気炉やAOD(Argon Oxygen Decarburization)炉、VOD(Vacuum Oxygen Decarburization)炉を用いて、上記溶鋼を製造する。製造された溶鋼に対して、必要に応じて周知の脱ガス処理を実施する。脱ガス処理を実施した溶鋼から、素材を製造する。素材の製造方法はたとえば、連続鋳造法である。連続鋳造法により、連続鋳造材(素材)を製造する。連続鋳造材はたとえば、スラブ、ブルーム及びビレット等である。溶鋼を造塊法によりインゴットにしてもよい。
準備された素材(連続鋳造材又はインゴット)を熱間加工して、オーステナイト系ステンレス鋼材を製造する。たとえば、素材を熱間圧延して鋼板や棒鋼、線材を製造する。また、熱間押出や熱間穿孔圧延等によりオーステナイト系ステンレス鋼管を製造する。熱間加工の具体的な方法は特に限定されず、最終製品の形状に応じた熱間加工を実施すればよい。熱間加工の加工終了温度はたとえば、1050℃以上である。ここでいう加工終了温度とは、最終の熱間加工が完了した直後の鋼材の温度を意味する。
熱間加工後のオーステナイト系ステンレス鋼材に対して、必要に応じて、冷間加工を実施してもよい。オーステナイト系ステンレス鋼材が棒鋼、線材、鋼管である場合、冷間加工はたとえば、冷間引抜や冷間圧延である。オーステナイト系ステンレス鋼材が鋼板である場合、冷間圧延等である。
熱間加工後、又は冷間加工後、必要に応じて、溶体化処理を実施してもよい。溶体化処理工程では、組織の均一化、及び炭窒化物の固溶を行う。好ましい溶体化処理温度は次のとおりである。
溶体化処理温度が1000℃以上であれば、Nbの炭窒化物が十分に固溶し、クリープ強度がさらに高まる。熱処理温度が1250℃以下であれば、Cの過剰な固溶を抑制でき、耐ポリチオン酸SCC性がさらに高まる。
各試験番号の鋼板に対して、高温環境下での使用を想定して、600℃で5000時間の時効処理を実施した。この時効処理材から、厚み2mm、幅10mm、長さ75mmの板状試験片を採取した。JIS G 0576(2001)「ステンレス鋼の応力腐食割れ試験方法」に準じて、耐ポリチオン酸SCC性評価試験を実施した。具体的には、試験片を、内側半径5mmのポンチ周りに曲げてUベンド形とした。Uベンド形の試験片を、Wackenroder溶液(蒸留水中にSO2ガスを吹き込んで作成したH2SO3飽和水溶液に多量のH2Sガスを吹き込んだ溶液)中に常温で100時間浸漬した。浸漬後の試験片に対して、割れ発生の有無を倍率500倍で顕微鏡観察して、割れの有無を確認した。
各試験番号の鋼板から、JIS Z2271(2010)に準拠したクリープ破断試験片を作製した。クリープ破断試験片の軸方向に垂直な断面は円形であり、クリープ破断試験片の外径は6mmであり、平行部は30mmであった。平行部は鋼板の圧延方向と平行であった。作製されたクリープ破断試験片を用いて、JIS Z2271(2010)に準拠したクリープ破断試験を実施した。具体的には、クリープ破断試験片を750℃で加熱した後、クリープ破断試験を実施した。試験応力は45MPaとし、クリープ破断時間(時間)及びクリープ破断絞り(%)を求めた。
表2に試験結果を示す。
Claims (5)
- 質量%で、
C:0.030%以下、
Si:0.10~1.00%、
Mn:0.20~2.00%、
P:0.040%以下、
S:0.010%以下、
Cr:16.0~25.0%、
Ni:10.0~30.0%、
Mo:0.1~5.0%、
Nb:0.20~1.00%、
N:0.050~0.300%、
sol.Al:0.0005~0.100%、
B:0.0010~0.0080%、
Cu:0~5.0%、
W:0~5.0%、
Co:0~1.0%、
V:0~1.00%、
Ta:0~0.2%、
Hf:0~0.20%、
Ca:0~0.010%、
Mg:0~0.010%、及び、
希土類元素:0~0.10%を含有し、残部がFe及び不純物からなり、
式(1)を満たす化学組成を有する、オーステナイト系ステンレス鋼。
B+0.004-0.9C+0.017Mo2≧0 (1)
ここで、式(1)の各元素記号には、対応する元素の含有量(質量%)が代入される。 - 請求項1に記載のオーステナイト系ステンレス鋼であって、
前記化学組成は、
Cu:0.1~5.0%、
W:0.1~5.0%、及び
Co:0.1~1.0%からなる群から選択される1種又は2種以上を含有する、オーステナイト系ステンレス鋼。 - 請求項1又は請求項2に記載のオーステナイト系ステンレス鋼であって、
前記化学組成は、
V:0.1~1.00%、
Ta:0.01~0.2%、及び
Hf:0.01~0.20%からなる群から選択される1種又は2種以上を含有する、オーステナイト系ステンレス鋼。 - 請求項1~請求項3のいずれか1項に記載のオーステナイト系ステンレス鋼であって、
前記化学組成は、
Ca:0.0005~0.010%、
Mg:0.0005~0.010%、及び、
希土類元素:0.001~0.10%からなる群から選択される1種又は2種以上を含有する、オーステナイト系ステンレス鋼。 - 請求項1に記載のオーステナイト系ステンレス鋼であって、
前記化学組成は、
Cu:0~1.9%を含有する、オーステナイト系ステンレス鋼。
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JPWO2021015283A1 (ja) * | 2019-07-25 | 2021-01-28 | ||
WO2021015283A1 (ja) * | 2019-07-25 | 2021-01-28 | 日本製鉄株式会社 | オーステナイト系ステンレス鋼材及び溶接継手 |
JP7277752B2 (ja) | 2019-07-25 | 2023-05-19 | 日本製鉄株式会社 | オーステナイト系ステンレス鋼材 |
CN115341144A (zh) * | 2019-07-25 | 2022-11-15 | 日本制铁株式会社 | 奥氏体系不锈钢钢材和焊接接头 |
JP2021066928A (ja) * | 2019-10-24 | 2021-04-30 | 日本製鉄株式会社 | オーステナイト系ステンレス鋼材 |
JP7339526B2 (ja) | 2019-10-24 | 2023-09-06 | 日本製鉄株式会社 | オーステナイト系ステンレス鋼材 |
JPWO2021141107A1 (ja) * | 2020-01-10 | 2021-07-15 | ||
KR20220124238A (ko) | 2020-01-10 | 2022-09-13 | 닛폰세이테츠 가부시키가이샤 | 오스테나이트계 스테인리스 강재 |
JP7307372B2 (ja) | 2020-01-10 | 2023-07-12 | 日本製鉄株式会社 | オーステナイト系ステンレス鋼材 |
WO2021141107A1 (ja) | 2020-01-10 | 2021-07-15 | 日本製鉄株式会社 | オーステナイト系ステンレス鋼材 |
JP2021113354A (ja) * | 2020-01-21 | 2021-08-05 | 日本製鉄株式会社 | オーステナイト系ステンレス鋼 |
JP7464817B2 (ja) | 2020-01-21 | 2024-04-10 | 日本製鉄株式会社 | オーステナイト系ステンレス鋼 |
WO2022255223A1 (ja) * | 2021-05-31 | 2022-12-08 | 日本製鉄株式会社 | オーステナイト系ステンレス鋼および鋼管 |
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EP3508602A1 (en) | 2019-07-10 |
US20190194787A1 (en) | 2019-06-27 |
EP3508602A4 (en) | 2020-04-01 |
CN109642291B (zh) | 2021-07-06 |
SG11201901278XA (en) | 2019-03-28 |
KR20190042675A (ko) | 2019-04-24 |
CA3035162A1 (en) | 2018-03-08 |
CN109642291A (zh) | 2019-04-16 |
KR102223549B1 (ko) | 2021-03-05 |
JP6904359B2 (ja) | 2021-07-14 |
CA3035162C (en) | 2021-12-14 |
JPWO2018043565A1 (ja) | 2019-06-24 |
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