WO2024070784A1 - Poudre d'acier inoxydable, élément en acier inoxydable et procédé de fabrication d'élément en acier inoxydable - Google Patents
Poudre d'acier inoxydable, élément en acier inoxydable et procédé de fabrication d'élément en acier inoxydable Download PDFInfo
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- WO2024070784A1 WO2024070784A1 PCT/JP2023/033803 JP2023033803W WO2024070784A1 WO 2024070784 A1 WO2024070784 A1 WO 2024070784A1 JP 2023033803 W JP2023033803 W JP 2023033803W WO 2024070784 A1 WO2024070784 A1 WO 2024070784A1
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- stainless steel
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- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 100
- 239000010935 stainless steel Substances 0.000 title claims abstract description 100
- 239000000843 powder Substances 0.000 title claims abstract description 59
- 238000004519 manufacturing process Methods 0.000 title claims description 33
- 239000002245 particle Substances 0.000 claims abstract description 34
- 239000000203 mixture Substances 0.000 claims abstract description 17
- 238000009826 distribution Methods 0.000 claims abstract description 6
- 230000001186 cumulative effect Effects 0.000 claims abstract description 5
- 238000012360 testing method Methods 0.000 claims description 69
- 238000000034 method Methods 0.000 claims description 38
- 229910000831 Steel Inorganic materials 0.000 claims description 28
- 238000001816 cooling Methods 0.000 claims description 28
- 239000010959 steel Substances 0.000 claims description 28
- 239000013078 crystal Substances 0.000 claims description 27
- 229910001566 austenite Inorganic materials 0.000 claims description 26
- 238000005496 tempering Methods 0.000 claims description 25
- 229910000734 martensite Inorganic materials 0.000 claims description 20
- 238000000465 moulding Methods 0.000 claims description 16
- 229910000859 α-Fe Inorganic materials 0.000 claims description 16
- 238000010438 heat treatment Methods 0.000 claims description 15
- 239000000654 additive Substances 0.000 claims description 14
- 230000000996 additive effect Effects 0.000 claims description 14
- 238000010791 quenching Methods 0.000 claims description 14
- 230000000171 quenching effect Effects 0.000 claims description 14
- 230000000717 retained effect Effects 0.000 claims description 12
- 238000009863 impact test Methods 0.000 claims description 9
- 239000012535 impurity Substances 0.000 claims description 5
- 230000007797 corrosion Effects 0.000 abstract description 101
- 238000005260 corrosion Methods 0.000 abstract description 101
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 abstract description 34
- 229910002092 carbon dioxide Inorganic materials 0.000 abstract description 17
- 239000001569 carbon dioxide Substances 0.000 abstract description 11
- 239000000460 chlorine Substances 0.000 abstract description 8
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 abstract description 6
- 229910052801 chlorine Inorganic materials 0.000 abstract description 3
- -1 chlorine ions Chemical class 0.000 abstract description 3
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 23
- 238000005336 cracking Methods 0.000 description 23
- 230000000694 effects Effects 0.000 description 18
- 230000007423 decrease Effects 0.000 description 17
- 238000011282 treatment Methods 0.000 description 17
- 239000007789 gas Substances 0.000 description 15
- 238000002844 melting Methods 0.000 description 14
- 230000008018 melting Effects 0.000 description 14
- 238000005259 measurement Methods 0.000 description 13
- 229910052761 rare earth metal Inorganic materials 0.000 description 13
- 150000002910 rare earth metals Chemical class 0.000 description 13
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 12
- 239000007788 liquid Substances 0.000 description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 9
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 8
- 229910045601 alloy Inorganic materials 0.000 description 8
- 239000000956 alloy Substances 0.000 description 8
- 239000000463 material Substances 0.000 description 7
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 6
- 239000003129 oil well Substances 0.000 description 6
- 238000003303 reheating Methods 0.000 description 6
- 239000011780 sodium chloride Substances 0.000 description 6
- 239000007864 aqueous solution Substances 0.000 description 5
- 239000002244 precipitate Substances 0.000 description 5
- 230000001681 protective effect Effects 0.000 description 5
- 229910052715 tantalum Inorganic materials 0.000 description 5
- 229910052726 zirconium Inorganic materials 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 238000011161 development Methods 0.000 description 4
- 239000006185 dispersion Substances 0.000 description 4
- 238000009689 gas atomisation Methods 0.000 description 4
- 239000003921 oil Substances 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 229910052718 tin Inorganic materials 0.000 description 4
- 239000011521 glass Substances 0.000 description 3
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 3
- 238000007654 immersion Methods 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 238000009864 tensile test Methods 0.000 description 3
- 238000010146 3D printing Methods 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000000889 atomisation Methods 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910001105 martensitic stainless steel Inorganic materials 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- OXNIZHLAWKMVMX-UHFFFAOYSA-N picric acid Chemical compound OC1=C([N+]([O-])=O)C=C([N+]([O-])=O)C=C1[N+]([O-])=O OXNIZHLAWKMVMX-UHFFFAOYSA-N 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 238000007493 shaping process Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000004580 weight loss Effects 0.000 description 2
- 238000005411 Van der Waals force Methods 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000010779 crude oil Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000001887 electron backscatter diffraction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 238000007500 overflow downdraw method Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 238000007712 rapid solidification Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000012085 test solution Substances 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 238000001132 ultrasonic dispersion Methods 0.000 description 1
- 238000009692 water atomization Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/05—Metallic powder characterised by the size or surface area of the particles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
- B22F10/30—Process control
- B22F10/34—Process control of powder characteristics, e.g. density, oxidation or flowability
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
- B22F10/60—Treatment of workpieces or articles after build-up
- B22F10/64—Treatment of workpieces or articles after build-up by thermal means
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/24—After-treatment of workpieces or articles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y10/00—Processes of additive manufacturing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y70/00—Materials specially adapted for additive manufacturing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/02—Making ferrous alloys by powder metallurgy
-
- 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
- C22C38/18—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
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
Definitions
- the present invention relates to a stainless steel powder suitable for manufacturing high-strength stainless steel couplings used in crude oil or natural gas oil wells and gas wells (hereinafter simply referred to as oil wells), as well as accessories such as parts and fittings.
- the present invention also relates to a stainless steel member formed using this stainless steel powder and a method for manufacturing a stainless steel member.
- Patent Documents 1 to 8 refer to 13Cr-stainless steel pipes.
- Patent Document 9 refers to a molding method involving a rapid melting and rapid solidification process.
- Patent Documents 1 to 9 may not be able to withstand the increasingly harsh development environments of oil and gas fields in recent years, such as by deteriorating corrosion resistance in high-temperature, severely corrosive environments containing carbon dioxide gas (CO 2 ) and chlorine ions ( Cl ⁇ ), or in environments containing hydrogen sulfide (H 2 S).
- CO 2 carbon dioxide gas
- Cl ⁇ chlorine ions
- H 2 S hydrogen sulfide
- an object of the present invention is to solve such problems of the conventional technology and to provide a stainless steel powder suitable for molding, capable of producing a stainless steel member having high strength, excellent low-temperature toughness, and excellent corrosion resistance, particularly in a high-temperature severe corrosive environment containing carbon dioxide gas (CO 2 ) and chlorine ions (Cl - ), an environment containing hydrogen sulfide (H 2 S), etc.
- Another object of the present invention is to provide a stainless steel member and a method for producing a stainless steel member having high strength, excellent low-temperature toughness, and excellent corrosion resistance in the above-mentioned environments.
- high strength refers to a yield strength of 655 MPa or more.
- excellent low-temperature toughness refers to a case where a Charpy impact test is performed on a V-notch test piece (10 mm thick) in accordance with the provisions of JIS Z 2242, with the test piece longitudinal direction perpendicular to the molding direction and the notch parallel to the molding direction, and the absorbed energy vE -10 at a test temperature of -10°C in the Charpy impact test is 40 J or more.
- excellent corrosion resistance refers to “excellent resistance to carbon dioxide corrosion” and “excellent resistance to sulfide stress corrosion cracking.”
- excellent carbon dioxide corrosion resistance refers to the case where, in the case where the Cr content in the steel is 14.0% or less, a test piece is immersed in a test liquid: a 20 mass % NaCl aqueous solution (liquid temperature: 150°C, CO2 gas atmosphere at 10 atmospheric pressure) held in an autoclave for an immersion time of 336 hours, the corrosion rate is 0.125 mm/y or less, and the test piece after the corrosion test is observed for the presence or absence of pitting corrosion on the surface of the test piece using a magnifying glass with a magnification of 10 times, and no pitting corrosion with a diameter of 0.2 mm or more is observed.
- a case where the Cr content in the steel exceeds 14.0% is defined as a case where a test piece is immersed in a test liquid: a 20 mass % NaCl aqueous solution (liquid temperature: 180°C, CO2 gas atmosphere at 10 atmospheric pressure) held in an autoclave for 336 hours, the corrosion rate is 0.125 mm/y or less, and the test piece surface after the corrosion test is observed for the presence or absence of pitting corrosion using a 10x magnifying glass, and no pitting corrosion with a diameter of 0.2 mm or more is found.
- excellent resistance to sulfide stress corrosion cracking refers to a case in which a test piece is immersed in a test liquid: a 5% by mass aqueous solution of NaCl (liquid temperature: 25°C, H2S : 0.1 atm, CO2 : 0.9 atm) adjusted to a pH of 3.5 by adding acetic acid and Na acetate, the immersion time is 720 hours, and a load stress of 90% of the yield stress is applied, and no cracks are generated in the test piece after the test.
- the inventors focused on additive manufacturing, a method of manufacturing three-dimensional objects using a 3D printer (3D printing).
- additive manufacturing the raw material stainless steel powder is rapidly heated and cooled during manufacturing, which significantly refines the structure and reduces or refines non-metallic inclusions (hereinafter referred to as inclusions), which are known to cause deterioration of corrosion resistance. Therefore, extensive research was conducted on the various factors that affect the strength, corrosion resistance, and low-temperature toughness of the component composition of stainless steel parts manufactured by additive manufacturing.
- an ingot produced by the melting-casting process was used as a master ingot, and then the master ingot was remelted and gas atomized to produce stainless steel powder, and the stainless steel powder was used to produce a shaped object by so-called 3D printing, and the above-mentioned various factors were examined.
- the components, particle size (median diameter of mass cumulative distribution (mass basis)) D50 , and apparent density of the stainless steel powder must be within the desired ranges.
- the present invention has been completed based on the above findings and further investigations.
- the gist of the present invention is as follows. [1] In mass%, C: 0.001 to 0.06%, Si: 0.01 to 1.0%, Mn: 0.01 to 2.0%, P: 0.05% or less, S: less than 0.005%, Cr: more than 11.0% and not more than 15.0%; Ni: 2.5 to 8.0%, V: 0.005 to 0.5%, Al: 0.1% or less, N: 0.100% or less, O: 0.3% or less, Mo: 3.5% or less, Contains The balance is Fe and unavoidable impurities, A particle diameter D50 , which is a median diameter at 50% of the cumulative mass distribution, is 10 to 200 ⁇ m; A stainless steel powder having an apparent density of 3.5 to 5.0 Mg/ m3 .
- the present invention provides stainless steel powder, a stainless steel member using the powder, and a method for manufacturing a stainless steel member.
- the stainless steel powder is suitable for use in manufacturing stainless steel members by additive manufacturing.
- the stainless steel member produced using the stainless steel powder of the present invention has high strength and excellent low-temperature toughness, and also has excellent corrosion resistance even at high temperatures of 150°C or higher, in severe corrosive environments containing CO 2 and Cl - , and in environments containing H 2 S, etc.
- the stainless steel powder of the present invention has a component composition described below, and has a particle size D50 and apparent density controlled within appropriate ranges.
- the stainless steel member of the present invention is manufactured from this stainless steel powder, and has the same component composition as the stainless steel powder described below, and a steel structure controlled within appropriate ranges.
- C 0.001 to 0.06% C is an important element that increases the strength of martensitic stainless steel.
- the C content is set to 0.001% or more.
- the C content is set to 0.005% or more. More preferably, the C content is set to 0.015% or more.
- the C content is set to 0.06% or less.
- the C content is set to 0.04% or less, and more preferably, the C content is set to 0.03% or less.
- Si 0.01 to 1.0% Si is an element that acts as a deoxidizer, and in order to obtain such an effect, it is necessary to contain 0.01% or more of Si. Therefore, the Si content is set to 0.01% or more. Preferably, the Si content is set to 0.1% or more. More preferably, the Si content is set to 0.15% or more. On the other hand, if the Si content exceeds 1.0%, the low-temperature toughness decreases. Therefore, the Si content is set to 1.0% or less. Preferably, the Si content is set to 0.8% or less. More preferably, the Si content is set to 0.6% or less. Further preferably, the Si content is set to 0.4% or less.
- Mn 0.01 to 2.0%
- Mn is an element that increases the strength of martensitic stainless steel, and in order to ensure the desired strength, it is necessary to contain 0.01% or more of Mn. Therefore, the Mn content is set to 0.01% or more.
- the Mn content is set to 0.1% or more. More preferably, the Mn content is set to 0.15% or more, and even more preferably, the Mn content is set to 0.25% or more.
- the Mn content is set to 2.0% or less.
- the Mn content is set to 1.0% or less. More preferably, the Mn content is set to 0.8% or less. Even more preferably, the Mn content is set to 0.6% or less.
- P 0.05% or less
- P is an element that reduces corrosion resistance such as carbon dioxide corrosion resistance and sulfide stress corrosion cracking resistance, and is preferably reduced as much as possible in the present invention, but 0.05% or less is acceptable. For this reason, the P content is set to 0.05% or less. Preferably, the P content is 0.03% or less. More preferably, the P content is 0.02% or less. There is no particular restriction on the lower limit, but preferably the P content is 0.005% or more.
- S less than 0.005%
- S is an element that reduces corrosion resistance, and it is preferable to reduce it as much as possible, but it is acceptable if it is less than 0.005%. For this reason, the S content is less than 0.005%.
- the S content is 0.003% or less. More preferably, the S content is 0.002% or less. There is no particular limit to the lower limit, but preferably, the S content is 0.0004% or more.
- Cr more than 11.0% and not more than 15.0% Cr is an element that forms a protective film on the steel pipe surface and contributes to improving corrosion resistance. If the Cr content is 11.0% or less, the desired corrosion resistance cannot be ensured. For this reason, the Cr content is set to more than 11.0%. Preferably, the Cr content is 11.5% or more. More preferably, the Cr content is 12.0% or more. Even more preferably, the Cr content is 12.5% or more. On the other hand, a Cr content of more than 15.0% is excessive for the purpose of obtaining the desired corrosion resistance and increases the cost. Furthermore, it is disadvantageous in terms of low temperature toughness. For this reason, the Cr content is set to 15.0% or less. Preferably, the Cr content is 14.5% or less. More preferably, the Cr content is 14.0% or less. Even more preferably, the Cr content is 13.5% or less.
- Ni 2.5 to 8.0%
- Ni is an element that strengthens the protective film on the steel pipe surface and contributes to improving corrosion resistance. Such an effect becomes prominent when the Ni content is 2.5% or more. For this reason, the Ni content is set to 2.5% or more.
- the Ni content is 3.0% or more. More preferably, the Ni content is 3.5% or more. Even more preferably, the Ni content is 5.0% or more.
- the Ni content is set to 8.0% or less.
- the Ni content is 7.5% or less. More preferably, the Ni content is 7.0% or less. Even more preferably, the Ni content is 6.5% or less.
- V 0.005 to 0.5%
- V is an element that contributes to improving strength by forming a solid solution, and also contributes to improving yield strength by combining with C and N and precipitating as V carbonitrides (V precipitates).
- the V content is set to 0.005% or more.
- the V content is set to 0.01% or more. More preferably, the V content is set to 0.02% or more. Even more preferably, the V content is set to 0.03% or more.
- a V content exceeding 0.5% leads to a decrease in low-temperature toughness and resistance to sulfide stress corrosion cracking. Therefore, the V content is set to 0.5% or less.
- the V content is set to 0.3% or less. More preferably, the V content is set to 0.2% or less. Even more preferably, the V content is set to 0.1% or less.
- Al 0.1% or less
- Al is an element that acts as a deoxidizer.
- the Al content is set to 0.1% or less.
- the Al content is 0.07% or less. More preferably, the Al content is 0.05% or less.
- the Al content is desirably 0% or more.
- the Al content is 0.01% or more. More preferably, the Al content is 0.02% or more.
- N 0.100% or less
- N is an element that improves pitting corrosion resistance.
- the N content exceeds 0.100%, nitrides are formed, which reduces low-temperature toughness and corrosion resistance. For this reason, the N content is set to 0.100% or less.
- the N content is 0.080% or less. More preferably, the N content is 0.070% or less. Even more preferably, the N content is 0.060% or less.
- the N content is desirably 0% or more.
- the N content is 0.005% or more.
- O 0.3% or less
- O oxygen
- the O content be 0.01% or more.
- the O content is 0.2% or less. More preferably, the O content is 0.1% or less.
- Mo 3.5% or less
- Mo is an element that stabilizes the protective film on the steel pipe surface, increases resistance to pitting corrosion caused by Cl- or low pH, and thereby enhances sulfide stress corrosion cracking resistance.
- the Mo content is preferably 0% or more.
- the Mo content is more preferably 0.4% or more, and even more preferably 1.0% or more. Most preferably, the Mo content is 1.8% or more.
- the Mo content of more than 3.5% increases the ferrite fraction and decreases the tempered martensite fraction, thereby causing a decrease in sulfide stress corrosion cracking resistance.
- Mo is an expensive element, which leads to an increase in material costs. For this reason, the Mo content is 3.5% or less.
- the Mo content is 3.2% or less. More preferably, the Mo content is less than 3.0%. Even more preferably, the Mo content is 2.7% or less. Most preferably, the Mo content is 2.5% or less.
- the remainder other than the above components is Fe and unavoidable impurities.
- the above-mentioned components are the basic component composition.
- the above-mentioned basic component composition provides the properties that the present invention aims to achieve.
- the following components may be added as optional elements as necessary to further improve strength, corrosion resistance, etc.
- Cu 3.5% or less
- the Cu content is preferably 0% or more. More preferably, the Cu content is 0.3% or more. Even more preferably, the Cu content is 0.5% or more. Most preferably, the Cu content is 1.0% or more.
- a Cu content of more than 3.5% leads to coarse Cu precipitation, which deteriorates the sulfide stress corrosion cracking resistance. Therefore, when Cu is contained, the Cu content is 3.5% or less.
- the Cu content is 3.0% or less. More preferably, the Cu content is 2.0% or less. Even more preferably, the Cu content is 1.5% or less.
- W 3.0% or less W is an important element that contributes to improving the strength of steel and stabilizes the protective film on the steel pipe surface to improve the resistance to sulfide stress corrosion cracking.
- W when contained in combination with Mo, significantly improves the resistance to sulfide stress corrosion cracking.
- the W content is preferably more than 0%. More preferably, the W content is 0.3% or more. Even more preferably, the W content is 0.5% or more. Most preferably, the W content is 0.8% or more.
- a W content of more than 3.0% promotes the precipitation of intermetallic compounds and reduces corrosion resistance. Therefore, when W is contained, the W content is 3.0% or less.
- the W content is 2.5% or less. More preferably, the W content is 2.0% or less. Even more preferably, the W content is 1.0% or less.
- Nb 0.5% or less Nb combines with C and N to precipitate as Nb carbonitride (Nb precipitate), which contributes to improving yield strength.
- the Nb content is preferably 0% or more. More preferably, the Nb content is 0.01% or more. Even more preferably, the Nb content is 0.05% or more.
- the Nb content exceeding 0.5% leads to a decrease in low temperature toughness and sulfide stress corrosion cracking resistance. Therefore, when Nb is contained, the Nb content is 0.5% or less.
- the Nb content is 0.3% or less. More preferably, the Nb content is 0.2% or less. Even more preferably, the Nb content is 0.1% or less.
- Ti, B, Zr, Co and Ta are all elements that increase strength, and one or more of these elements may be selected and contained as necessary. In addition to the above effects, Ti, B, Zr, Co and Ta also have the effect of improving sulfide stress corrosion cracking resistance.
- Ta is an element that brings about the same effect as Nb, and part of Nb can be replaced with Ta.
- Ti, B, Zr, Co and Ta are optional elements and do not need to be contained, and each content is preferably 0% or more. In other words, when Ti is contained, the Ti content is preferably 0% or more, and more preferably 0.01% or more. When B is contained, the B content is preferably 0% or more, and more preferably 0.0001% or more.
- the Zr content is preferably 0% or more, and more preferably 0.01% or more.
- Co is contained
- Ta is contained
- the Ta content is preferably 0% or more, more preferably 0.01% or more.
- the content exceeds Ti: 0.30%, B: 0.0050%, Zr: 0.2%, Co: 1.0%, and Ta: 0.1%, respectively, the low-temperature toughness decreases. Therefore, when Ti is contained, the Ti content is 0.30% or less, preferably 0.10% or less.
- B the B content is 0.0050% or less, preferably 0.0030% or less.
- the Zr content is 0.2% or less, preferably 0.05% or less.
- Co is contained
- the Co content is 1.0% or less, preferably 0.4% or less.
- Ta is contained, the Ta content is 0.1% or less, preferably 0.03% or less.
- Ca and REM are both elements that contribute to improving resistance to sulfide stress corrosion cracking through controlling the morphology of sulfides.
- Ca and REM are optional elements and do not need to be contained, and their respective contents are preferably 0% or more. However, when they are contained to obtain the effects described above, it is preferable to contain 0.0001% or more of Ca. It is more preferable to make the Ca content 0.001% or more. When REM is contained, it is preferable to contain 0.001% or more of REM. It is more preferable to make the REM content 0.003% or more.
- the Ca content is 0.050% or less. It is preferable to make the Ca content 0.005% or less.
- the REM content is 0.1% or less. It is preferable to make the REM content 0.01% or less.
- Mg, Sn and Sb are all elements that improve corrosion resistance. Note that Mg, Sn and Sb are optional elements and do not have to be contained, and the content of each is preferably 0% or more. However, when they are contained to obtain the above-mentioned effects, it is preferable to contain Mg: 0.002% or more, Sn: 0.01% or more and Sb: 0.01% or more, respectively. In other words, when Mg is contained, the Mg content is preferably 0% or more, and more preferably 0.002% or more. When Sn is contained, the Sn content is preferably 0% or more, and more preferably 0.01% or more. When Sb is contained, the Sb content is preferably 0% or more, and more preferably 0.01% or more.
- the Mg content is 0.01% or less. If Sn is included, the Sn content should be 0.5% or less. The Sn content should preferably be 0.2% or less. If Sb is included, the Sb content should be 0.5% or less. The Sb content should more preferably be 0.2% or less.
- the stainless steel powder of the present invention has a particle size defined by D 50 of 10 to 200 ⁇ m. If the particle size D 50 is too fine, the powder will have uneven filling due to a decrease in the fluidity of the powder, which will cause defects such as voids to be generated during additive manufacturing. As a result, low-temperature toughness and corrosion resistance (pitting corrosion resistance, SSCC resistance) will be significantly reduced. Since the above phenomenon occurs when the particle size D 50 is less than 10 ⁇ m, the particle size D 50 is set to 10 ⁇ m or more.
- the particle size D 50 is preferably 15 ⁇ m or more, more preferably 20 ⁇ m or more, and even more preferably 30 ⁇ m or more.
- the particle size D 50 is set to 200 ⁇ m or less.
- the particle size D50 is preferably 175 ⁇ m or less, more preferably 150 ⁇ m or less, even more preferably 125 ⁇ m or less, and most preferably 100 ⁇ m or less.
- the D50 particle size of the stainless steel powder refers to the median diameter, which is the value at the 50% position of the cumulative mass distribution of the powder.
- a laser diffraction particle size measuring device can be used to measure the median diameter.
- the particle size D50 of the stainless steel powder is measured by the method described below.
- Laser diffraction particle size measuring devices include the LA-950V2 manufactured by Horiba, Ltd. Of course, other devices can be used, but it is preferable to use a device with a lower limit of 0.1 ⁇ m or less and an upper limit of 45 ⁇ m or more for accurate measurement. In other words, it is preferable to use a device that can measure the range of 0.1 to 45 ⁇ m.
- a laser beam is irradiated onto the solvent in which the iron powder is dispersed, and the particle size distribution and average particle size of the iron powder are measured from the diffraction and scattering intensity of the laser beam.
- ethanol which has good particle dispersibility and is easy to handle.
- the dispersion treatment time is varied between 0 and 60 minutes at seven stages at 10 minute intervals, and the average particle size of the iron powder is measured after each dispersion treatment. During each measurement, the solvent is stirred to prevent particle aggregation. The smallest particle size value among the seven measurements obtained by changing the dispersion treatment time at 10 minute intervals is used as the particle size (particle size D50 ) of the iron powder.
- the apparent density is set to 3.5 Mg/ m3 or more.
- the apparent density is set to 3.7 Mg/ m3 or more, and more preferably, the apparent density is set to 4.0 Mg/ m3 or more.
- the apparent density is set to 5.0 Mg/ m3 or less.
- the apparent density is set to 4.8 Mg/ m3 or less, and more preferably, the apparent density is set to 4.6 Mg/ m3 or less.
- the apparent density shall be the value measured using the test method specified in JIS Z 2504.
- the alloy powder can be used as stainless steel powder for molding, for example, for cladding, 3D printers, sintering, etc. It is particularly suitable as an alloy powder for 3D printers.
- the stainless steel member of the present invention is formed from the stainless steel powder described above, has the above-mentioned composition, and has a steel structure consisting of, by volume, 45% or more of tempered martensite phase, 0-40% of ferrite phase, and 25% or less of retained austenite phase.
- the stainless steel member of the present invention has a tempered martensite phase as the main phase in order to ensure the strength (yield strength) targeted by the present invention.
- main phase refers to a structure that occupies 45% or more by volume of the steel member. If the tempered martensite phase is less than 45%, the desired strength cannot be obtained. For this reason, the tempered martensite phase is set to 45% or more.
- the tempered martensite phase is preferably set to 55% or more.
- the tempered martensite phase is more preferably set to 60% or more, and even more preferably set to 70% or more.
- the upper limit of the tempered martensite phase may be 100%.
- the remainder other than the main phase is ferrite phase, or retained austenite phase, or ferrite phase and retained austenite phase.
- the volume fraction of the ferrite phase is 40% or less.
- the volume fraction of the ferrite phase is preferably 20% or less, more preferably 10% or less, even more preferably 5% or less, and most preferably 3% or less.
- the stainless steel member of the present invention can have 0% ferrite phase, since the above-mentioned effects can be obtained even if it is a single phase of tempered martensite.
- the stainless steel member of the present invention can obtain the above-mentioned effects even if it is a single phase of tempered martensite, so the austenite phase (residual austenite phase) may be 0%.
- the austenite phase may be precipitated at a volume fraction of more than 10%. More preferably, the residual austenite is 13% or more, and even more preferably, 15% or more.
- the residual austenite phase is set to a volume fraction of 25% or less.
- the residual austenite is 23% or less by volume. Even more preferably, the residual austenite is 20% or less by volume.
- the above-mentioned steel structure of the stainless steel member of the present invention can be measured by the following method.
- a test piece for microstructure observation is taken from a cross section perpendicular to the direction of the material (steel member) manufactured by additive manufacturing or the like.
- the test piece for microstructure observation is corroded with Villela's reagent (a mixture of picric acid, hydrochloric acid, and ethanol in proportions of 2 g, 10 ml, and 100 ml, respectively), and the structure is imaged with a scanning electron microscope (accelerating voltage: 15 kV, magnification: 1000 times).
- the structure fraction (area fraction %) of the ferrite phase is calculated using an image analyzer, and this area fraction is regarded as the volume fraction (%) of the ferrite phase.
- the X-ray diffraction specimen is then ground and polished so that the cross section perpendicular to the shaping direction becomes the measurement surface, and the amount of retained austenite ( ⁇ ) is measured using an X-ray diffraction method.
- the amount of retained austenite is measured by measuring the integrated intensity of the diffracted X-rays from the (220) plane of ⁇ and the (211) plane of ⁇ , and converting it into a volume fraction using the following formula.
- ⁇ (volume ratio) 100 / (1 + (I ⁇ R ⁇ / I ⁇ R ⁇ ))
- I ⁇ is the integrated intensity of ⁇
- R ⁇ is the theoretically calculated value of ⁇
- I ⁇ is the integrated intensity of ⁇
- R ⁇ is the theoretically calculated value of ⁇ .
- the structural fraction (volume percentage) of tempered martensite phase is the remainder other than the ferrite phase and the retained austenite phase.
- the steel structure of the stainless steel member of the present invention can be adjusted to fall within the ranges of each of the above phases by appropriately controlling the heat treatment processes (quenching and tempering) described below.
- the stainless steel member of the present invention has the specific component composition described above, and the steel structure is adjusted to consist of, by volume, 45% or more tempered martensite phase, 0-40% ferrite phase, and 25% or less retained austenite phase, thereby achieving the strength and properties (corrosion resistance, low-temperature toughness) targeted by the present invention.
- the number of inclusions having a major axis of 2 ⁇ m or more is preferably 10/mm2 or less. Inclusions having a major axis of 2 ⁇ m or more become the starting point of pitting corrosion when a sulfide stress corrosion cracking resistance test is performed. Pitting corrosion is accompanied by stress concentration and hydrogen generation, which causes sulfide stress cracking. Therefore, in order to improve the sulfide stress corrosion cracking resistance, it is preferable to reduce the number of inclusions having a major axis of 2 ⁇ m or more. This effect can be obtained if the number of inclusions having a major axis of 2 ⁇ m or more is 10/ mm2 or less.
- the number of inclusions having a major axis of 2 ⁇ m or more it is preferable to set the number of inclusions having a major axis of 2 ⁇ m or more to 10/mm2 or less . It is more preferable to set the number of inclusions having a major axis of 2 ⁇ m or more to 7/ mm2 or less, and even more preferable to set it to 4/ mm2 or less. There is no particular limit to the lower limit of the number of inclusions having a major axis of 2 ⁇ m or more, and it is preferable that the number of inclusions having a major axis of 2 ⁇ m or more is 0/mm2 or more .
- the number of crystal grains having a grain size of 5 ⁇ m or more among the crystal grains having an orientation difference of 5° or more with adjacent grains is 10% or less of the total crystal grains.
- Crystal grains having a grain size of 5 ⁇ m or more deteriorate low-temperature toughness and resistance to sulfide stress corrosion cracking. Therefore, in order to improve low-temperature toughness and resistance to sulfide stress corrosion cracking, it is preferable to make the crystal grain size small. This effect can be obtained by making the number of crystal grains having a grain size of 5 ⁇ m or more among the crystal grains having an orientation difference of 5° or more with adjacent grains 10% or less of the total crystal grains.
- the number of crystal grains having a grain size of 5 ⁇ m or more among the crystal grains having an orientation difference of 5° or more with adjacent grains 10% or less of the total number of crystal grains. It is more preferable that the number of crystal grains having a grain size of 5 ⁇ m or more be 9% or less of the total number of crystal grains, and even more preferable that it be 8% or less. There is no particular limit to the lower limit of the number of crystal grains having a grain size of 5 ⁇ m or more among the crystal grains having an orientation difference of 5° or more with adjacent grains, and 0% or more is preferable.
- the stainless steel member of the present invention has a yield strength of 655 MPa or more. Although there is no particular upper limit, it is preferably 900 MPa or less in order to prevent a decrease in low-temperature toughness. In a Charpy impact test, the absorbed energy vE -10 at a test temperature of -10°C is 40 J or more. Although there is no particular upper limit, it is preferably 300 J or less. Furthermore, the stainless steel member of the present invention is also excellent in toughness at a test temperature of -60°C in a Charpy impact test, and the absorbed energy vE -60 is preferably 40 J or more. Also, the absorbed energy vE -60 is preferably 200 J or less.
- the stainless steel powder of the present invention is provided in the final material form through the following series of manufacturing processes.
- the stainless steel powder of the present invention is manufactured through the steps of melting, forming an ingot, remelting the master ingot, and producing powder through an atomization process.
- a predetermined amount of the above-mentioned elements is melted as materials in a high-frequency vacuum melting furnace, alloyed, and cast to produce an ingot (master ingot).
- the reason for setting these conditions is as follows. If the melting temperature is too low, the molten steel will solidify and clog the nozzle when it is dropped from the nozzle. There is no particular limit to the upper limit of the melting temperature, but it is preferable that the melting temperature be 1700°C or lower.
- the melting furnace used in this process is not limited to a high-frequency vacuum melting furnace, and other melting furnaces (for example, a direct current heating type melting furnace) can also be used in the present invention.
- the cast master ingot is used as the material, remelted in a melting furnace such as a high-frequency or induction furnace, and a powder with a low oxygen content is obtained by gas atomization using inert gases such as Ar or He.
- These powders are then classified into particles of 10 to 200 ⁇ m and used as the stainless steel powder of the present invention.
- Classification may be performed using a sieve or other methods such as air flow classification.
- water atomization may be used instead of gas atomization.
- the apparent density is controlled by appropriately adjusting the gas pressure, gas flow rate, gas temperature, and focusing angle during gas atomization.
- the manufacturing method of the stainless steel component of the present invention includes a molding process and a heat treatment process.
- the stainless steel powder described above is used to create a stainless steel additive model (three-dimensional structure) by, for example, additive manufacturing (metal powder additive manufacturing).
- a 3D printer method can be used.
- a laser-type powder bed fusion 3D printer is used.
- No particular setting conditions for the 3D printer are specified. From the viewpoint of preventing overmelting or undermelting, for example, it is preferable that the laser output is 150 to 300 W and the scan speed is 700 to 1100 mm/s.
- the 3D structure after molding is subjected to quenching and tempering under predetermined conditions to obtain the stainless steel member of the present invention.
- an average cooling rate faster than air cooling is 0.01°C/s or more.
- an average cooling rate faster than water cooling is 0.2°C/s or more.
- the heating temperature in the quenching treatment is set to 850° C. or higher, preferably 880° C. or higher, and more preferably 900° C. or higher.
- the heating temperature in the quenching treatment is set to 1150° C. or lower, preferably 1050° C. or lower, and more preferably 1000° C. or lower.
- the reheating temperature for 10 minutes or more. It is more preferable to hold the reheating temperature for 15 minutes or more. It is preferable to hold the reheating temperature for 60 minutes or less. It is more preferable to hold the reheating temperature for 30 minutes or less.
- the cooling rate of the quenching treatment is air-cooled or faster in order to ensure the desired low-temperature toughness. It is preferable that the average cooling rate is 0.01°C/s or more. It is more preferable that the average cooling rate of the quenching treatment is 0.1°C/s or more. It is preferable that the average cooling rate of the quenching treatment is 200°C/s or less. It is more preferable that the average cooling rate of the quenching treatment is 100°C/s or less.
- the average cooling rate is the average of the cooling rates from the start of cooling to the end of cooling.
- the cooling end temperature is a temperature at which the surface temperature of the three-dimensional structure is 50°C or less. It is preferably 40°C or less, and more preferably 30°C or less. If the temperature exceeds 50°C, residual austenite will precipitate excessively, and the desired high strength cannot be obtained. Although there is no particular lower limit, it is preferable that the cooling end temperature is 5°C or more.
- tempering temperature is set to 650°C or lower. It is preferable that the tempering temperature (tempering temperature) is set to 630°C or lower. On the other hand, if the tempering temperature is less than 500°C, the strength will be excessively high, and the desired low-temperature toughness will not be obtained. Therefore, the tempering temperature is set to 500°C or higher. It is preferable that the tempering temperature is set to 525°C or higher.
- the tempering temperature for 10 minutes or more. It is more preferable to hold the tempering temperature for 20 minutes or more. It is preferable that the holding time at the tempering temperature is 60 minutes or less. It is more preferable that the holding time at the tempering temperature is 40 minutes or less.
- the cooling rate in the tempering treatment is preferably equal to or faster than air cooling. More preferably, the average cooling rate is equal to or faster than 0.01°C/s. Even more preferably, the average cooling rate is equal to or faster than 0.1°C/s.
- the cooling rate in the tempering treatment is preferably equal to or slower than 200°C/s. More preferably, the cooling rate in the tempering treatment is equal to or slower than 100°C/s.
- the three-dimensional structure may be further machined before or after the above-mentioned heat treatment process in order to obtain the desired shape.
- the stainless steel parts of the present invention made from the stainless steel powder of the present invention have high strength, excellent corrosion resistance and low-temperature toughness, and therefore can be suitably used as constituent materials (e.g., sliding parts) for equipment such as compressors and pumps used in highly corrosive environments such as oil wells. They can also be used as couplings and accessories for oil wells. Furthermore, according to the present invention, it is possible to reduce the manufacturing costs of special parts in various shapes and also to improve dimensional accuracy.
- the manufacturing method of the stainless steel powder (powder alloy) shown in Table 1 will be described in detail.
- the predetermined amounts of the component compositions shown in Table 1 were melted in a high-frequency vacuum melting furnace (Ar atmosphere under reduced pressure, melting temperature 1600°C or higher) and cast to produce master ingots of these alloys.
- the master ingots of the alloys were remelted in an Ar atmosphere and powdered by a gas atomization method to obtain powder alloys.
- each alloy powder (stainless steel powder) with a different particle size D50 was obtained by classification.
- the particle size D50 and apparent density of the stainless steel powder were measured by the above-mentioned methods, and the values are shown in Table 2.
- Test pieces were taken from each of the obtained stainless steel components using the methods described below, and microstructural observation, measurement of the number of inclusions, measurement of grain size, tensile testing, Charpy impact testing, and corrosion resistance testing were carried out.
- the test methods were as follows:
- a test piece for structure observation was taken from the obtained stainless steel member so that the cross section perpendicular to the molding direction (perpendicular to the lamination surface) was the observation surface.
- the obtained test piece for structure observation was corroded with Villela's reagent (a mixture of picric acid, hydrochloric acid, and ethanol in proportions of 2 g, 10 ml, and 100 ml, respectively), and the structure was imaged with a scanning electron microscope (accelerating voltage: 15 kv, magnification: 1000 times).
- the structure fraction (area fraction) of the ferrite phase was calculated using an image analyzer, and this was taken as the volume fraction (%) of the ferrite phase.
- a test piece for X-ray diffraction was taken from the obtained stainless steel member, and ground and polished so that the cross section perpendicular to the molding direction became the measurement surface.
- the amount of retained austenite ( ⁇ ) was measured using an X-ray diffraction method.
- the amount of retained austenite was measured by measuring the integrated intensity of the diffracted X-rays of the (220) plane of ⁇ and the (211) plane of ⁇ , and converting it into a volume fraction using the following formula.
- ⁇ (volume ratio) 100 / (1 + (I ⁇ R ⁇ / I ⁇ R ⁇ ))
- I ⁇ is the integrated intensity of ⁇
- R ⁇ is the theoretically calculated value of ⁇
- I ⁇ is the integrated intensity of ⁇
- R ⁇ is the theoretically calculated value of ⁇
- the structural fraction (volume %) of tempered martensite phase was calculated as the remainder other than the ferrite phase and the retained austenite phase.
- the number of inclusions was measured by taking a 500 mm2 region from 1/2 the thickness as a scanning electron microscope (SEM) sample of a cross section perpendicular to the molding direction. For each sample, the inclusions were identified by SEM observation, and the number of inclusions per unit area was calculated. Inclusions with a major axis of 2 ⁇ m or more were identified by binarizing the contrast of the backscattered electron image of the scanning electron microscope to define the outer periphery of the inclusion, and measuring the major axis from the outer periphery of the inclusion.
- SEM scanning electron microscope
- the grain size measurement sample was taken from a position of 1/2 the thickness of the cross section perpendicular to the molding direction. After EBSD observation (acceleration voltage: 15 kv, step size: 0.5 ⁇ m) was performed on the taken sample in an area of 300 ⁇ m in the width direction and 500 ⁇ m in the thickness direction, a crystal with an orientation difference of 5° or more was defined as one crystal, and the proportion of crystal grains with a grain size of 5 ⁇ m or more was measured by the intercept method.
- Corrosion Resistance Test As the corrosion resistance test, a corrosion test and a sulfide stress corrosion cracking resistance test (SSCC resistance test) were carried out.
- condition B When the Cr content was more than 14% (condition B), the above corrosion test piece was immersed in a test liquid: 20 mass% NaCl aqueous solution (liquid temperature: 180°C, 10 atm CO2 gas atmosphere) held in an autoclave, and the immersion period was set to 14 days (336 hours). The weight of the test piece after the corrosion test was measured, and the corrosion rate was calculated from the weight loss before and after the corrosion test. A corrosion rate of 0.125 mm/y or less was considered to be acceptable, and a corrosion rate of more than 0.125 mm/y was considered to be unacceptable.
- the test pieces were examined using a 10x magnifying glass to check for the presence or absence of pitting corrosion on the surface of the test piece.
- the presence of pitting corrosion refers to the presence of pitting corrosion with a diameter of 0.2 mm or more.
- specimens without pitting corrosion were rated as passing, and specimens with pitting corrosion were rated as failing.
- a material with a corrosion rate of 0.125 mm/y or less and no occurrence of pitting corrosion is evaluated as having excellent carbon dioxide corrosion resistance.
- SSCC resistance test From the obtained stainless steel member, a round bar-shaped test piece (diameter: 6.4 mm ⁇ ) was machined so that the longitudinal direction of the test piece was perpendicular to the molding direction, and a sulfide stress corrosion cracking test (SSCC (Sulfide Stress Corrosion Cracking) test) was performed in accordance with NACE (National Association of Corrosion and Engineering) TM0177 Method A.
- NACE National Association of Corrosion and Engineering
- the SSCC resistance test was carried out by immersing the test specimens in a test solution of 5 mass% NaCl solution (liquid temperature: 25°C, H2S : 0.1 atm, CO2 : 0.9 atm) adjusted to pH 3.5 by adding acetic acid + Na acetate, for 720 hours, and applying 100% of the yield stress as a load stress. After the test, the test specimens were observed for the presence or absence of cracks. Here, specimens without cracks were judged as passing, and specimens with cracks were judged as failing.
- the examples of the present invention were all stainless steel powders in which the above-mentioned component composition, particle size D50 and apparent density were controlled within appropriate ranges.
- the stainless steel members fabricated from these steel powders had high strength and excellent low-temperature toughness in low-temperature environments, as well as excellent corrosion resistance in high-temperature severe corrosive environments containing CO 2 and Cl - and in environments containing H 2 S.
- the stainless steel powder was not controlled within the appropriate range, and the stainless steel parts manufactured from the steel powder did not have at least one of the properties of yield strength, corrosion resistance, and low temperature toughness that are the objective of the present invention.
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Abstract
L'objectif de la présente invention est de fournir une poudre d'acier inoxydable qui peut être utilisée pour produire un élément en acier inoxydable ayant une robustesse élevée, une excellente ténacité à basse température, et une excellente résistance à la corrosion dans un environnement corrosif agressif à haute température comprenant du dioxyde de carbone (CO2) et des ions chlore (Cl-) ou dans un environnement comprenant du sulfure d'hydrogène (H2S). La poudre d'acier inoxydable possède une composition spécifique, un diamètre particulaire D50, qui est le diamètre médian situé au 50ème percentile de la distribution massique cumulée, de 10 à 200 µm, et une densité apparente de 3,5 à 5,0 mg/m3.
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WO2019225281A1 (fr) * | 2018-05-25 | 2019-11-28 | Jfeスチール株式会社 | Tuyau sans soudure en acier inoxydable martensitique pour tuyaux de puits de pétrole et son procédé de production |
WO2020071348A1 (fr) * | 2018-10-02 | 2020-04-09 | 日本製鉄株式会社 | Tuyau sans soudure en acier inoxydable à base de martensite |
WO2021218932A1 (fr) * | 2020-04-30 | 2021-11-04 | 宝山钢铁股份有限公司 | Acier inoxydable martensitique résistant à la corrosion à haute température et à haute résistance et procédé de fabrication associé |
JP2022006584A (ja) * | 2020-06-24 | 2022-01-13 | Jfeスチール株式会社 | ステンレス鋼粉末、ステンレス鋼部材およびステンレス鋼部材の製造方法 |
WO2022181164A1 (fr) * | 2021-02-26 | 2022-09-01 | Jfeスチール株式会社 | Tube sans soudure en acier inoxydable à haute résistance pour puits de pétrole et son procédé de production |
-
2023
- 2023-09-15 JP JP2023576337A patent/JPWO2024070784A1/ja active Pending
- 2023-09-15 WO PCT/JP2023/033803 patent/WO2024070784A1/fr unknown
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JPH07150287A (ja) * | 1993-12-01 | 1995-06-13 | Kawasaki Steel Corp | 鋼管継手カップリング素管の製造方法及びそれに用いる鉄粉 |
JPH10130787A (ja) * | 1996-10-29 | 1998-05-19 | Kawasaki Steel Corp | 耐応力腐食割れ性および高温引張り特性に優れた油井管用高強度マルテンサイト系ステンレス鋼 |
JP2014025145A (ja) * | 2012-06-21 | 2014-02-06 | Jfe Steel Corp | 耐食性に優れた油井用高強度ステンレス鋼継目無管およびその製造方法 |
WO2019225281A1 (fr) * | 2018-05-25 | 2019-11-28 | Jfeスチール株式会社 | Tuyau sans soudure en acier inoxydable martensitique pour tuyaux de puits de pétrole et son procédé de production |
WO2020071348A1 (fr) * | 2018-10-02 | 2020-04-09 | 日本製鉄株式会社 | Tuyau sans soudure en acier inoxydable à base de martensite |
WO2021218932A1 (fr) * | 2020-04-30 | 2021-11-04 | 宝山钢铁股份有限公司 | Acier inoxydable martensitique résistant à la corrosion à haute température et à haute résistance et procédé de fabrication associé |
JP2022006584A (ja) * | 2020-06-24 | 2022-01-13 | Jfeスチール株式会社 | ステンレス鋼粉末、ステンレス鋼部材およびステンレス鋼部材の製造方法 |
WO2022181164A1 (fr) * | 2021-02-26 | 2022-09-01 | Jfeスチール株式会社 | Tube sans soudure en acier inoxydable à haute résistance pour puits de pétrole et son procédé de production |
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