WO2022224640A1 - Tuyau en acier inoxydable et son procédé de fabrication - Google Patents

Tuyau en acier inoxydable et son procédé de fabrication Download PDF

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Publication number
WO2022224640A1
WO2022224640A1 PCT/JP2022/011814 JP2022011814W WO2022224640A1 WO 2022224640 A1 WO2022224640 A1 WO 2022224640A1 JP 2022011814 W JP2022011814 W JP 2022011814W WO 2022224640 A1 WO2022224640 A1 WO 2022224640A1
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steel pipe
stainless steel
content
temperature
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PCT/JP2022/011814
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English (en)
Japanese (ja)
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健一郎 江口
正雄 柚賀
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Ｊｆｅスチール株式会社
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Priority to BR112023021507A priority Critical patent/BR112023021507A2/pt
Priority to JP2022536963A priority patent/JP7279863B2/ja
Priority to EP22791420.7A priority patent/EP4293133A1/fr
Priority to CN202280028088.0A priority patent/CN117120653A/zh
Publication of WO2022224640A1 publication Critical patent/WO2022224640A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
    • C21D8/105—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
    • C21D9/085—Cooling or quenching
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
    • 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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/001—Austenite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite

Definitions

  • the present invention relates to a stainless steel pipe suitable for use in oil and gas wells for crude oil or natural gas (hereinafter simply referred to as oil wells) and geothermal wells, and a method for manufacturing the same.
  • 13Cr martensitic stainless steel pipes have generally been used as oil country tubular goods for mining in oil and gas fields in environments containing carbon dioxide gas (CO 2 ), chloride ions (Cl ⁇ ), and the like. Recently, however, the development of oil wells in corrosive environments at even higher temperatures (up to 200°C) has progressed, and in such environments, 13Cr martensitic stainless steel pipes sometimes lack corrosion resistance. rice field. Therefore, there has been a demand for oil well steel pipes having excellent corrosion resistance that can be used in such environments.
  • CO 2 carbon dioxide gas
  • Cl ⁇ chloride ions
  • geothermal wells that collect steam for geothermal power generation are also being developed in deeper layers than before.
  • Patent Document 1 describes a high-strength stainless steel pipe for oil wells with improved corrosion resistance.
  • C 0.005 to 0.05%
  • Si 0.05 to 0.5%
  • Mn 0.2 to 1.8%
  • P 0 .03% or less
  • S 0.005% or less
  • Cr 15.5-18%
  • Ni 1.5-5%
  • Mo 1-3.5%
  • V 0.02-0.2%
  • N 0.01 to 0.15%
  • O 0.006% or less
  • Cr, Ni, Mo, Cu and C satisfy a specific relational expression
  • Cr, Mo, Si, C It has a composition containing Mn, Ni, Cu and N so as to satisfy a specific relational expression, and further has a martensite phase as a base phase, a ferrite phase at a volume fraction of 10 to 60%, or an austenite phase at a volume fraction.
  • Patent Document 2 describes a high-strength stainless steel pipe for oil wells with improved toughness and corrosion resistance.
  • C 0.04% or less
  • Si 0.50% or less
  • Mn 0.20 to 1.80%
  • P 0.03% or less
  • S 0.005% or less
  • Cr 15.5 to 17.5%
  • Ni 2.5 to 5.5%
  • V 0.20% or less
  • Mo 1.5 to 3.5%
  • W 0.50 to 3.0%
  • Al 0.05% or less
  • N 0.15% or less
  • Cr, Mo, W and C have a specific relationship, and , Cr, Mo, W, Si, C, Mn, Cu, Ni and N satisfy specific relationships, and Mo and W satisfy specific relationships, respectively; and a steel pipe having a structure containing 10 to 50% by volume of ferrite phase.
  • Patent Document 3 describes a high-strength stainless steel pipe with improved sulfide stress cracking resistance and high-temperature carbon dioxide corrosion resistance.
  • C 0.05% or less
  • Si 1.0% or less
  • P 0.05% or less
  • S less than 0.002%
  • Cr 16% More than 18% or less
  • Mo more than 2% and 3% or less
  • Cu 1-3.5%
  • Ni 3% or more and less than 5%
  • Al 0.001-0.1%
  • Mn 1%
  • the composition contains Mn and N so as to satisfy a specific relationship, so that the martensite phase is the main component and the ferrite phase is 10 to 40% by volume.
  • Patent Document 4 describes a stainless steel pipe for oil wells.
  • C 0.05% or less
  • Si 0.5% or less
  • Mn 0.01 to 0.5%
  • P 0.04% or less
  • S 0.01% or less
  • Cr more than 16.0 to 18.0%
  • Ni more than 4.0 to 5.6%
  • Mo 1.6 to 4.0%
  • Cu 1.5 to 3.0%
  • Al 0.001 to 0.10%
  • N 0.050% or less
  • Cr, Cu, Ni and Mo satisfy a specific relationship
  • C + N Mn, Ni
  • Stainless steel for oil wells having a plurality of imaginary line segments arranged in a row within a range of 200 ⁇ m, a structure in which the ratio of fer
  • Patent Document 5 describes a high-strength stainless steel pipe for oil wells with high toughness and improved corrosion resistance.
  • C 0.04% or less
  • Si 0.50% or less
  • Mn 0.20 to 1.80%
  • P 0.03% or less
  • S 0.005% or less
  • Cr 15.5 to 17.5%
  • Ni 2.5 to 5.5%
  • V 0.20% or less
  • Mo 1.5 to 3.5%
  • W 0.50 to 3.0%
  • Al 0.05% or less
  • N 0.15% or less
  • Cr, Mo, W and C satisfy a specific relationship , Cr, Mo, W, Si, C, Mn, Cu, Ni and N satisfying the specified relationship, and Mo and W satisfying the specified relationship, and the largest crystal
  • a steel pipe having a grain structure in which the distance between any two points within a grain is 200 ⁇ m or less.
  • This steel pipe has a high yield strength exceeding 654 MPa (95 ksi), has sufficient toughness, and has sufficient corrosion resistance in a high-temperature corrosion environment of 170°C or higher containing CO 2 , Cl ⁇ , and H 2 S. is intended to indicate
  • Patent Document 6 describes a high-strength martensitic stainless steel seamless steel pipe for oil wells.
  • C 0.01% or less
  • Si 0.5% or less
  • Mn 0.1 to 2.0%
  • P 0.03% or less
  • S 0.005% or less
  • Cr more than 15.5 and 17.5% or less
  • Ni 2.5 to 5.5%
  • Mo 1.8 to 3.5%
  • Cu 0.3 to 3.5 %
  • V 0.20% or less
  • Al 0.05% or less
  • N 0.06% or less
  • the seamless steel pipe has a structure containing an austenite phase and a tempered martensite phase as the remainder.
  • the composition in addition to the above composition, may contain W: 0.25 to 2.0% and/or Nb: 0.20% or less. As a result, it has a high strength with a yield strength of 655 MPa or more and 862 MPa or less, a tensile property with a yield ratio of 0.90 or more , and a high temperature of 170 ° C. It is possible to stably manufacture high-strength martensitic stainless steel seamless steel pipes for oil wells that have sufficient corrosion resistance (carbon dioxide corrosion resistance and sulfide stress cracking resistance) even in severe corrosive environments.
  • Patent Document 7 describes a stainless steel pipe for oil wells.
  • C 0.05% or less
  • Si 1.0% or less
  • Mn 0.01 to 1.0%
  • P 0.05% or less
  • S less than 0.002%
  • Cr 16-18%
  • Mo 1.8-3%
  • Cu 1.0-3.5%
  • Co 0.01 ⁇ 1.0%
  • Al 0.001 to 0.1%
  • O 0.05% or less
  • N 0.05% or less
  • Cr, Ni, Mo and Cu satisfy a specific relationship
  • the stainless steel pipe has a structure containing 10% or more and less than 60% by volume of ferrite phase, 10% or less of retained austenite phase, and 40% or more of martensite phase.
  • Patent Document 8 describes a stainless steel material.
  • C 0.040% or less
  • Si 0.05 to 1.0%
  • Mn 0.010 to 0.30%
  • Cr 18.0%
  • Cu 1.5 to 4.0%
  • sol.Al 0.001 to 0.100%
  • Mo 0 to 0.60%
  • W 0-2.0%
  • Co 0-0.30%
  • Ti 0-0.10%
  • V 0-0.15%
  • Zr 0-0.10%
  • Nb 0-0.10%
  • Ca 0-0.010%
  • Mg 0-0.010%
  • REM 0-0.05%
  • B 0-0.005%
  • the balance consists of Fe and impurities , among the impurities, P, S, O, and N are respectively P: 0.050% or less, S: less than 0.0020%, O: 0.020% or less, N: 0.020% or less
  • C N, Si, Mn, Ni, Cr, Cu
  • Patent Document 1 8 cannot maintain the desired corrosion resistance (carbon dioxide gas corrosion resistance, sulfide stress cracking resistance). In addition, considering the use in cold regions, it is also required to have both high strength and low temperature toughness.
  • An object of the present invention is to solve the problems of the prior art and to provide a stainless steel pipe having a yield strength of 758 MPa or more, excellent low-temperature toughness, and excellent corrosion resistance, and a method for producing the same.
  • excellent corrosion resistance in the present invention means excellent carbon dioxide corrosion resistance and sulfide stress cracking resistance.
  • Excellent carbon dioxide corrosion resistance in the present invention means that a test piece is placed in a test liquid: 25 mass% NaCl aqueous solution (liquid temperature: 250 ° C., 30 atm CO2 gas atmosphere) held in an autoclave.
  • a test liquid 25 mass% NaCl aqueous solution (liquid temperature: 250 ° C., 30 atm CO2 gas atmosphere) held in an autoclave.
  • the corrosion rate is 0.125 mm/y or less when the test piece is immersed and the immersion period is 336 hours, and no pitting corrosion occurs in the test piece after the corrosion test, and the test solution is 0.01 mol/L H 2 SO 4 aqueous solution (liquid temperature: 250° C., 30 atm CO 2 gas atmosphere)
  • the test piece was immersed for 336 hours, and the corrosion rate was 0.125 mm/y or less and the corrosion test was performed. It refers to the case where no pitting corrosion occurred in the later test piece.
  • the "excellent sulfide stress cracking resistance" in the present invention refers to a sulfide stress cracking test (SSC test) that evaluates the cracking susceptibility of a test piece to which stress is applied in a corrosive environment containing H2S . , refers to low sulfide stress cracking susceptibility.
  • test liquid 5% by mass NaCl aqueous solution (liquid temperature: 25°C, 0.95 atm CO2 gas, 0.05 atm H2S atmosphere) to obtain a pH:
  • the test piece is immersed in an aqueous solution adjusted to 3.5, the immersion time is 720 hours, and the test is performed with a load stress of 90% of the yield stress, and no cracks occur in the test piece after the test. shall mean the case.
  • excellent low temperature toughness (high toughness) in the present invention refers to the absorbed energy vE -10 at a test temperature of -10 ° C in a Charpy impact test conducted in accordance with the provisions of JIS Z 2242 (2016). is 40J or more.
  • the above absorbed energy vE -10 is preferably 250J or less.
  • the present inventors used, as a stainless steel pipe, a seamless steel pipe having a stainless steel composition that has a yield strength of 758 MPa or more and high toughness, and has corrosion resistance (carbon dioxide corrosion resistance and corrosion resistance).
  • corrosion resistance carbon dioxide corrosion resistance and corrosion resistance.
  • Various factors that affect the sulfide stress cracking resistance have been extensively studied.
  • the gist of the present invention is as follows. [1] in % by mass, C: 0.05% or less, Si: 1.0% or less, Mn: 0.10-2.0%, P: 0.05% or less, S: less than 0.005%, Cr: more than 16.0% and 20.0% or less, Mo: more than 0.6% and less than 1.4%, Ni: 3.0% or more and less than 5.0%, Al: 0.001 to 0.10%, N: 0.010 to 0.100%, O: 0.01% or less, Cu: 0.3-3.5% and satisfies the formulas (1) and (2), with the balance being Fe and unavoidable impurities, Having a structure consisting of a tempered martensite phase of 45% or more, a ferrite phase of 20 to 40%, and a retained austenite phase of 5% or more and 25% or less, in volume fraction, Yield strength is 758 MPa or more, A stainless steel pipe having an absorbed energy v
  • Group A One or more selected from Ti: 0.3% or less, Nb: 0.5% or less, V: 0.5% or less, Ta: 0.5% or less
  • Group C Mg: 0.010% or less and Zr: 0.2 1 or 2 selected from % or less
  • Group D 1 or 2 selected from Sn: 0.20% or less and Sb: 0.20% or less
  • Group E Co: 1.0 % or less and W: 3.0% or less, one or two selected from [3] [1] or [2], A steel pipe material is heated at a temperature in the range of 1100 to 1350° C.
  • the seamless steel pipe is reheated to a temperature in the range of 850 to 1150°C, and subjected to a quenching treatment in which the surface temperature is cooled to a cooling stop temperature of 50°C or less and over 0°C at a cooling rate faster than air cooling.
  • a method for manufacturing a stainless steel pipe which is then subjected to a tempering treatment of heating to a tempering temperature in the range of 500 to 650°C.
  • the yield strength (YS) is high strength of 758 MPa or more, low temperature toughness at -10 ° C., high temperature of 250 ° C. or more, and excellent even in severe corrosive environments containing CO 2 and Cl - It is possible to provide a stainless steel pipe having excellent corrosion resistance and a method for manufacturing the same. Moreover, the stainless steel pipe of the present invention can be suitably used as a seamless stainless steel pipe for oil wells.
  • C 0.05% or less C is an important element that increases the strength of martensitic stainless steel. In the present invention, it is desirable to contain 0.003% or more of C in order to ensure the desired high strength. On the other hand, when the C content exceeds 0.05%, the sulfide stress cracking resistance is lowered. Therefore, the C content should be 0.05% or less.
  • the C content is preferably 0.005% or more.
  • the C content is preferably 0.040% or less, more preferably 0.035% or less.
  • Si 1.0% or less
  • Si is an element that acts as a deoxidizing agent, and in order to obtain such an effect, it is desirable to contain 0.005% or more of Si.
  • the Si content is set to 1.0% or less.
  • the Si content is more preferably 0.1% or more, more preferably 0.25% or more.
  • the Si content is preferably 0.6% or less.
  • Mn 0.10-2.0%
  • Mn is an element that increases the strength of martensitic stainless steel, and in order to ensure the strength targeted in the present invention, the content of Mn is required to be 0.10% or more. On the other hand, when the Mn content exceeds 2.0%, the low temperature toughness is lowered. Therefore, the Mn content should be 0.10 to 2.0%.
  • the Mn content is preferably 0.15% or more, more preferably 0.20% or more.
  • the Mn content is preferably 0.5% or less.
  • P 0.05% or less
  • P is an element that lowers corrosion resistance such as carbon dioxide corrosion resistance and sulfide stress cracking resistance, and is preferably reduced as much as possible in the present invention.
  • P content of 0.05% or less is permissible. Therefore, the P content should be 0.05% or less.
  • the P content is preferably 0.02% or less.
  • the lower limit of the P content is not particularly limited. However, excessive reduction causes an increase in manufacturing costs, so the P content is preferably 0.005% or more.
  • S less than 0.005%
  • S is an element that significantly lowers hot workability and hinders stable operation of the hot pipe-making process, and is preferably reduced as much as possible in the present invention. If the S content is less than 0.005%, the pipe can be manufactured by the process described later. For this reason, the S content is set to less than 0.005%.
  • the S content is preferably 0.0015% or less, more preferably 0.0010% or less.
  • the lower limit of the S content is not particularly limited. However, excessive reduction causes an increase in manufacturing costs, so the S content is preferably 0.0003% or more.
  • Cr more than 16.0% and not more than 20.0% Cr is an element that forms a protective film on the steel pipe surface and contributes to the improvement of corrosion resistance. If the Cr content is 16.0% or less, the corrosion resistance intended in the present invention cannot be ensured. Therefore, the content of Cr exceeding 16.0% is required. On the other hand, if the Cr content exceeds 20.0%, the ferrite phase fraction becomes too high, and the strength aimed at in the present invention cannot be secured. Therefore, the Cr content should be more than 16.0% and 20.0% or less. The Cr content is preferably 17.0% or more. The Cr content is preferably 19.0% or less.
  • Mo more than 0.6% and less than 1.4% Mo stabilizes the protective film on the steel pipe surface and increases the resistance to pitting corrosion caused by Cl ⁇ and low pH, thereby improving sulfide stress cracking resistance. It is an element that enhances. In order to obtain such an effect, it is necessary to contain Mo over 0.6%.
  • the Cr content exceeds 16.0%, the content of Mo of 1.4% or more increases the fraction of ferrite phase and causes a decrease in low temperature toughness. Therefore, the Mo content should be more than 0.6% and less than 1.4%.
  • the Mo content is preferably 0.7% or more.
  • the Mo content is preferably 1.2% or less, more preferably 1.1% or less.
  • Ni 3.0% or more and less than 5.0%
  • Ni is an element that strengthens the protective film on the steel pipe surface and contributes to the improvement of corrosion resistance. Such an effect becomes remarkable when the Ni content is 3.0% or more.
  • the Ni content should be 3.0% or more and less than 5.0%.
  • the Ni content is preferably 3.5% or more.
  • the Ni content is preferably 4.5% or less.
  • Al 0.001-0.10%
  • Al is an element that acts as a deoxidizing agent. In order to obtain such effects, the content of Al must be 0.001% or more. On the other hand, if the Al content exceeds 0.10%, the amount of oxides increases and the cleanliness decreases, thereby lowering the low temperature toughness. Therefore, the Al content is set to 0.001 to 0.10%.
  • the Al content is preferably 0.01% or more, more preferably 0.02% or more.
  • the Al content is preferably 0.07% or less, more preferably 0.040% or less.
  • N 0.010 to 0.100%
  • N is an element that improves pitting corrosion resistance. In order to obtain such effects, 0.010% or more of N is contained. On the other hand, if the N content exceeds 0.100%, nitrides are formed to lower the low temperature toughness. Therefore, the N content should be 0.010 to 0.100%.
  • the N content is preferably 0.02% or more.
  • the N content is preferably 0.06% or less.
  • O 0.01% or less O (oxygen) exists as an oxide in steel, and thus has an adverse effect on various properties. Therefore, in the present invention, it is desirable to reduce it as much as possible. In particular, when O exceeds 0.01%, the hot workability, corrosion resistance and low temperature toughness deteriorate. Therefore, the O content is set to 0.01% or less.
  • the O content is preferably 0.0050% or less.
  • the O content is preferably 0.0010% or more, more preferably 0.0025% or more.
  • Cu 0.3-3.5%
  • Cu has the effect of strengthening the protective film on the surface of the steel pipe, suppressing the penetration of hydrogen into the steel, and increasing the resistance to sulfide stress cracking. In order to obtain such an effect, 0.3% or more of Cu is required.
  • the Cu content should be 0.3 to 3.5%.
  • the Cu content is preferably 0.5% or more, more preferably 1.0% or more, and still more preferably 1.5% or more.
  • the Cu content is preferably 3.0% or less.
  • Cr, Ni, Mo, W, Cu and C are contained within the above-described content range and adjusted so as to satisfy the formula (1).
  • Cr, Ni, Mo, W, Cu and C in the formula (1) are the contents (% by mass) of the respective elements, and the contents of the elements not contained are zero.
  • the left-side value of formula (1) is 21.7 or more.
  • the left side value of formula (1) shall be calculated with the element concerned being zero (zero).
  • the left-side value of formula (1) is preferably 22.0 or more. Note that there is no particular upper limit for the left-side value of expression (1). From the viewpoint of suppressing an increase in cost and a decrease in strength due to excessive alloying, the left-side value of the formula (1) is preferably 26.0 or less, more preferably 24.0 or less.
  • Cr, Mo, W and C are contained within the above-described content range and adjusted so as to satisfy the formula (2).
  • Cr, Mo, W and C in the formula (2) are the content (% by mass) of each element, and the content of the element not contained is zero.
  • the left-side value of formula (2) is 21.0 or more.
  • the left-side value of formula (2) is preferably 21.5 or more. Note that there is no particular upper limit for the left-side value of expression (2). Since the effect saturates, the left-side value of formula (2) is preferably 28.0 or less, more preferably 25.0 or less.
  • the balance other than the above components consists of iron (Fe) and unavoidable impurities.
  • the basic components of the present invention are the components described above. By having these basic components and satisfying all of the above-described formulas (1) and (2), the stainless steel pipe of the present invention can obtain the desired properties.
  • the following selective elements can be contained as necessary.
  • each component of Ti, Nb, V, Ta, B, Ca, REM, Mg, Zr, Sn, Sb, Co, and W below can be contained as necessary, these components are 0%. There may be.
  • Ti, Nb, V and Ta are elements that increase the strength, and if necessary, one or more of Ti, Nb, V and Ta can be selected and contained.
  • Ti, Nb, V and Ta also have the effect of improving sulfide stress cracking resistance by trapping hydrogen atoms when hydrogen generated by corrosion penetrates into the steel.
  • Ta is an element that provides the same effect as Nb, and part of Nb can be replaced with Ta. In order to obtain such effects, it is desirable to contain Ti: 0.01% or more, Nb: 0.01% or more, V: 0.01% or more, and Ta: 0.01% or more.
  • Ti: 0.3%, Nb: 0.5%, V: 0.5%, and Ta: 0.5% are contained, respectively, the low temperature toughness decreases. Therefore, when Ti, Nb, V and Ta are contained, Ti: 0.3% or less, Nb: 0.5% or less, V: 0.5% or less and Ta: 0.5% or less is preferred. More preferably, Ti: 0.02% or more, Nb: 0.02% or more, V: 0.03% or more, and Ta: 0.03% or more. More preferably, Ti: 0.2% or less, Nb: 0.3% or less, V: 0.2% or less, and Ta: 0.2% or less.
  • B 0.0050% or less, Ca: 0.0050% or less, and REM: 0.010% or less
  • B 0.0050% or less B improves grain boundary strength It is an element that improves hot workability by reducing the In order to obtain such an effect, it is desirable to contain 0.0010% or more of B.
  • B is preferably 0.0050% or less.
  • the B content is more preferably 0.0020% or more.
  • the B content is more preferably 0.0040% or less.
  • Both Ca and REM are elements that contribute to improving sulfide stress cracking resistance through morphology control of sulfides, and are necessary. may contain one or both of Ca and REM depending on the In order to obtain such effects, it is desirable to contain Ca: 0.0001% or more and REM: 0.001% or more.
  • Ca: 0.0050% or less and REM: 0.010% or less it is preferable that Ca: 0.0050% or less and REM: 0.010% or less, respectively. More preferably, Ca: 0.0005% or more and REM: 0.005% or more. More preferably, Ca: 0.0040% or less and REM: 0.008% or less.
  • Mg: 0.010% or less, Zr: 0.2% or less Both Mg and Zr are inclusions is an element that improves corrosion resistance by controlling the morphology of Mg and Zr.
  • Mg: 0.010% or less and Zr: 0.2% or less it is preferable that Mg: 0.010% or less and Zr: 0.2% or less, respectively. More preferably, Mg: 0.003% or more and Zr: 0.02% or more. More preferably, Mg: 0.005% or less and Zr: 0.1% or less.
  • Sn 0.20% or less and Sb: 0.20% or less Sn: 0.20% or less, Sb: 0.20% or less It is an element that improves corrosion resistance by suppressing and promoting passivation, and one or both of Sn and Sb can be selected and contained as necessary. In order to obtain such effects, it is desirable to contain Sn: 0.01% or more and Sb: 0.01% or more. On the other hand, even if the Sn content exceeds 0.20% and the Sb content exceeds 0.20%, the effect is saturated, and the effect commensurate with the content cannot be expected. Therefore, when Sn and Sb are contained, it is preferable that Sn: 0.20% or less and Sb: 0.20% or less, respectively. More preferably, Sn: 0.02% or more and Sb: 0.02% or more. More preferably, Sn: 0.15% or less and Sb: 0.15% or less.
  • Co raises the Ms point to increase the fraction of the retained austenite phase. It is an element that reduces S and improves strength and resistance to sulfide stress cracking, and can be selected and contained. In order to obtain such effects, it is desirable to contain 0.01% or more of Co. On the other hand, even if the Co content exceeds 1.0%, the effect is saturated. Therefore, when Co is contained, the Co content is set to 1.0% or less.
  • the Co content is preferably 0.01% or more, more preferably 0.05% or more, and still more preferably 0.07% or more.
  • the Co content is preferably 0.15% or less, more preferably 0.09% or less.
  • W 3.0% or less W is an element that contributes to the improvement of the strength of steel, stabilizes the protective film on the surface of the steel pipe, and increases the resistance to sulfide stress cracking. can do.
  • W is contained in combination with Mo, the resistance to sulfide stress cracking is remarkably improved.
  • the content of W exceeding 3.0% lowers the low temperature toughness due to the formation of intermetallic compounds. Therefore, when W is contained, the W content should be 3.0% or less.
  • the W content is preferably 0.1% or more, more preferably 0.5% or more, and still more preferably 0.8% or more.
  • the W content is preferably 2.0% or less.
  • the stainless steel pipe of the present invention has the chemical composition described above, and has a tempered martensite phase of 45% or more, a ferrite phase of 20 to 40%, and a retained austenite of 5% or more and 25% or less in volume fraction. It has a structure consisting of phases.
  • the tempered martensite phase is the main phase in order to ensure the desired strength.
  • the "main phase” refers to a structure that occupies 45% or more of the volume of the entire steel pipe.
  • the volume fraction of the tempered martensite phase is preferably 50% or more, more preferably 55% or more.
  • the volume fraction of the tempered martensite phase is preferably 75% or less, more preferably 70% or less.
  • Ferrite phase 20 to 40% by volume
  • at least a ferrite phase is precipitated as a second phase in a volume ratio of 20% or more with respect to the entire steel pipe.
  • the ferrite phase becomes resistant to the progress of cracking, so the progress of sulfide stress cracking can be suppressed, and the corrosion resistance aimed at in the present invention can be secured. be able to.
  • the desired strength may not be ensured.
  • the ferrite phase should be 20 to 40% by volume.
  • the volume ratio of the ferrite phase is preferably 23% or more, more preferably 26% or more.
  • the volume fraction of the ferrite phase is preferably 37% or less, more preferably 34% or less.
  • the austenite phase (retained austenite phase) is precipitated as the second phase.
  • the presence of the retained austenite phase which has excellent ductility and low-temperature toughness, improves the ductility and low-temperature toughness of the steel as a whole.
  • the retained austenite phase is precipitated at a volume ratio of 5% or more in the entire steel pipe.
  • precipitation of a large amount of austenite phase exceeding 25% in volume fraction cannot ensure desired strength because austenite has lower strength than martensite phase and ferrite phase. Therefore, the volume fraction of the retained austenite phase is set to 5% or more and 25% or less.
  • the volume fraction of the retained austenite phase is preferably over 10%, preferably 20% or less, and more preferably 15% or less.
  • Each tissue of the present invention described above can be measured by the following method.
  • a test piece for tissue observation was taken from the central portion of the wall thickness of a cross section perpendicular to the tube axis direction, and corroded with a Villella reagent (picric acid, hydrochloric acid, and ethanol mixed in proportions of 2 g, 10 ml, and 100 ml, respectively).
  • the structure is imaged with a scanning electron microscope (magnification: 1000 times), the structure fraction (area %) of the ferrite phase is calculated using an image analyzer, and this area ratio is treated as the volume ratio %.
  • the X-ray diffraction test piece is ground and polished so that the cross section (C cross section) perpendicular to the tube axis direction becomes the measurement surface, and the amount of retained austenite ( ⁇ ) is measured using the X-ray diffraction method. .
  • the amount of retained austenite is obtained by measuring the diffraction X-ray integrated intensity of the (220) plane of ⁇ and the (211) plane of ⁇ (ferrite) and converting it using the following formula.
  • ⁇ (volume ratio) 100/(1 + (I ⁇ R ⁇ /I ⁇ R ⁇ ))
  • I ⁇ integrated intensity of ⁇
  • R ⁇ theoretical crystallographically calculated value of ⁇
  • I ⁇ integrated intensity of ⁇
  • R ⁇ theoretically calculated crystallographic value of ⁇
  • the fraction (volume ratio) of the tempered martensite phase is the remainder other than the ferrite phase and the residual ⁇ phase.
  • the above structure of the present invention can be adjusted by heat treatment (quenching treatment and tempering treatment) under specific conditions, which will be described later.
  • the content range of the above-described components, the specific component composition satisfying the formulas (1) and (2), and the volume fraction of tempered marten of 45% or more By adjusting the structure to consist of a site phase, 20 to 40% ferrite phase, and 5% to 25% retained austenite phase, the above-mentioned properties aimed at in the present invention can be obtained.
  • a steel pipe material having the chemical composition described above is used as a starting material.
  • the method of manufacturing the steel pipe material, which is the starting material is not particularly limited.
  • the molten steel having the above composition is melted by a melting method such as a converter, and cast into a billet (steel pipe material) by a casting method such as a continuous casting method or an ingot-slabbing-rolling method. is preferred.
  • the manufacturing method of a steel pipe material is not limited to this method.
  • the slab may be further subjected to hot rolling to obtain a steel slab having desired dimensions and shape, and the resulting slab may be used as a steel pipe material.
  • the steel pipe material for example, billet
  • the heating temperature in the heating step is set to a temperature in the range of 1100 to 1350.degree.
  • the heating temperature is preferably 1150° C. or higher and preferably 1300° C. or lower.
  • the term "decreased hot workability" in the present invention means that a round bar test piece having a parallel part diameter of 10 mm was taken from a billet and tested with a Gleeble tester. After heating to 1250 ° C., holding for 100 seconds, cooling at 1 ° C./sec to 1000 ° C., holding for 10 seconds, pulling until it breaks, and evaluating by measuring the cross-sectional reduction rate (%) The cross-sectional reduction rate is less than 70%.
  • the heated steel pipe material is then subjected to hot working in a hot pipe making process to form a seamless steel pipe of a predetermined shape.
  • the hot tube-making process is preferably a Mannesmann-plug mill system or Mannesmann-mandrel mill system hot tube-making process.
  • a seamless steel pipe may be produced by hot extrusion using a press method. In the hot pipe-making process, it is sufficient that a seamless steel pipe having a predetermined shape can be produced, and no particular conditions are defined.
  • the obtained seamless steel pipe may be subjected to a cooling treatment (cooling process).
  • the cooling step need not be particularly limited.
  • the steel pipe is cooled to room temperature at a cooling rate similar to that of air cooling, so that the structure of the steel pipe has a martensite phase as the main phase. can be done.
  • the seamless steel pipe is subjected to heat treatment including quenching treatment and tempering treatment.
  • the seamless steel pipe is reheated to a temperature (heating temperature) in the range of 850 to 1150°C, held for a predetermined time, and then cooled at a cooling rate higher than air cooling so that the surface temperature of the seamless steel pipe is 50°C or lower and exceeds 0°C. (cooling stop temperature).
  • the heating temperature of the quenching treatment is less than 850° C., the Ac 3 point or less is achieved, so reverse transformation from martensite to austenite does not occur. Also, transformation from austenite to martensite does not occur during cooling in the quenching process. As a result, it is not possible to ensure the desired strength in the present invention.
  • the heating temperature of the quenching treatment exceeds 1150° C. and becomes high, the crystal grains become coarse. As a result, the low temperature toughness value decreases. Therefore, the heating temperature for the quenching treatment is set to a temperature in the range of 850 to 1150.degree.
  • the heating temperature is preferably 900° C. or higher.
  • the heating temperature is preferably 1000° C. or lower.
  • the seamless steel pipe is heated to the above heating temperature and then held for a predetermined time.
  • the soaking time is preferably 5 to 40 minutes (min) in order to uniformize the temperature in the wall thickness direction of the seamless steel pipe and prevent fluctuations in the material quality.
  • the soaking time is more preferably 10 minutes or more.
  • the cooling stop temperature in cooling in the quenching treatment is set at 50°C or lower and higher than 0°C.
  • the cooling stop temperature is preferably 10° C. or higher.
  • the cooling stop temperature is preferably 40° C. or lower.
  • cooling rate equal to or higher than air cooling means an average cooling rate of 0.01°C/sec or higher.
  • the tempering process is a process in which the seamless steel pipe is heated to a temperature (tempering temperature) in the range of 500 to 650° C., held for a predetermined time, and allowed to cool.
  • Air cooling is air cooling.
  • the tempering temperature should be in the range of 500 to 650°C.
  • the tempering temperature is preferably 520°C or higher, more preferably 550°C or higher.
  • the tempering temperature is preferably 630°C or lower, more preferably 600°C or lower.
  • the seamless steel pipe is heated at the tempering temperature and then held for a predetermined time.
  • the soaking time (holding time) is preferably 5 to 90 minutes (min) in order to uniformize the temperature in the wall thickness direction of the seamless steel pipe and to prevent the material from fluctuating.
  • the soaking time (holding time) is more preferably 15 minutes or longer.
  • the soaking time (holding time) is more preferably 60 minutes or less.
  • the structure of the steel pipe obtained has a tempered martensite phase as the main phase as described above, and a structure composed of a ferrite phase and a retained austenite phase. becomes.
  • the high-strength seamless stainless steel pipe for oil wells having high strength, high toughness and excellent corrosion resistance which is the object of the present invention, can be obtained.
  • the stainless steel pipe obtained by the present invention has a yield strength (YS) of 758 MPa or more, excellent low-temperature toughness, and excellent corrosion resistance.
  • Yield strength is preferably 800 MPa or more.
  • the yield strength is preferably 1034 MPa or less.
  • a heating process was performed in which molten steel having the chemical composition shown in Table 1 was melted by vacuum melting, and the obtained steel pipe material (slab) was heated at the heating temperature shown in Table 2.
  • test material was cut out from the obtained seamless steel pipe, and the test material was subjected to heat treatment (quenching treatment and tempering treatment) under the conditions shown in Table 2.
  • the test material was sampled so that the longitudinal direction of the test piece was aligned with the tube axis direction.
  • the average cooling rate in water cooling during quenching treatment was 11° C./sec
  • the average cooling rate in air cooling (air cooling) during tempering treatment was 0.04° C./sec.
  • “-" in "Component composition” in Table 1 indicates that it is not intentionally added, and includes not only the case of not containing (0%) but also the case of unavoidably containing.
  • test piece was taken from the obtained heat-treated test material, and a structure observation, tensile test, impact test, and corrosion resistance test were performed using the test piece.
  • the methods for each test were as follows.
  • an X-ray diffraction test piece is taken from the obtained heat-treated test material, ground and polished so that the cross section (C section) perpendicular to the tube axis direction becomes the measurement surface, and the X-ray diffraction method is performed. was used to measure the amount of retained austenite ( ⁇ ).
  • the amount of retained austenite was obtained by measuring the diffraction X-ray integrated intensity of the (220) plane of ⁇ and the (211) plane of ⁇ (ferrite) and converting it using the following formula.
  • ⁇ (volume ratio) 100/(1 + (I ⁇ R ⁇ /I ⁇ R ⁇ ))
  • I ⁇ integrated intensity of ⁇
  • R ⁇ theoretical crystallographically calculated value of ⁇
  • I ⁇ integrated intensity of ⁇
  • R ⁇ theoretically calculated crystallographic value of ⁇
  • the fraction (volume ratio) of the tempered martensite phase was the remainder other than the ferrite phase and the residual ⁇ phase.
  • Corrosion resistance test A corrosion test was performed using a corrosion test piece as follows to evaluate carbon dioxide corrosion resistance and sulfide stress cracking resistance.
  • a corrosion test piece having a thickness of 3 mm, a width of 30 mm, and a length of 40 mm was machined from the obtained heat-treated test material.
  • a corrosion test was carried out as follows using the corrosion test piece. (Corrosion test A) In the corrosion test, the corrosion test piece was immersed in a test liquid: 25 mass% NaCl aqueous solution (liquid temperature: 250 ° C., 30 atm CO 2 gas atmosphere) held in an autoclave, and the immersion period was 14 days ( 336 hours). The weight of the test piece after the corrosion test was measured, and the corrosion rate calculated from the weight loss before and after the corrosion test was obtained. Here, a corrosion rate of 0.125 mm/y or less was evaluated as acceptable, and a corrosion rate exceeding 0.125 mm/y was evaluated as unacceptable.
  • pitting corrosion present refers to the case where pitting corrosion having a diameter of 0.2 mm or more occurs.
  • No pitting corrosion means the case where no pitting corrosion occurs and the case where the pitting corrosion is less than 0.2 mm in diameter.
  • Corrosion test B The corrosion test was carried out by immersing the corrosion test piece in a test liquid: 0.01 mol/L H 2 SO 4 aqueous solution (liquid temperature: 250°C, 30 atm CO 2 gas atmosphere) held in an autoclave. A period of 14 days (336 hours) was performed. The weight of the test piece after the corrosion test was measured, and the corrosion rate calculated from the weight loss before and after the corrosion test was obtained. Here, a corrosion rate of 0.125 mm/y or less was evaluated as acceptable, and a corrosion rate exceeding 0.125 mm/y was evaluated as unacceptable.
  • pitting corrosion present refers to the case where pitting corrosion having a diameter of 0.2 mm or more occurs.
  • No pitting corrosion means the case where no pitting corrosion occurs and the case where the pitting corrosion is less than 0.2 mm in diameter.
  • the corrosion rate in corrosion test A was 0.125 mm / y or less and the pitting corrosion did not occur
  • the corrosion rate in corrosion test B was 0.125 mm / y or less and the pitting corrosion was evaluated as having excellent carbon dioxide gas corrosion resistance.
  • a round-bar-shaped test piece (diameter: 6.4 mm ⁇ ) was produced from the obtained heat-treated test material by machining according to NACE (National Association of Corrosion and Engineers) TM0177 Method A.
  • a sulfide stress cracking resistance test (SSC (Sulfide Stress Cracking) resistance test) was carried out as follows using the round bar-shaped test piece.
  • the SSC resistance test was carried out by adding acetic acid + Na acetate to a test liquid: 5 mass% NaCl aqueous solution (liquid temperature: 25 ° C., CO 2 : atmosphere of 0.95 atm, H 2 S: 0.05 atm), pH: 3
  • the test piece was immersed in an aqueous solution adjusted to 0.5, the immersion period was set to 720 hours, and 90% of the yield stress was applied as the load stress.
  • the presence or absence of cracks was observed for the test piece after the SSC resistance test. Here, those without cracks were evaluated as acceptable, and those with cracks were evaluated as unacceptable.
  • All of the examples of the present invention have high strength with a yield strength (YS) of 758 MPa or more, excellent low temperature toughness, and are excellent at high temperatures of 250 ° C. or more and in severe corrosive environments containing CO 2 and Cl - . It had corrosion resistance (excellent carbon dioxide corrosion resistance and excellent sulfide stress cracking resistance).

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Abstract

L'invention concerne un tuyau en acier inoxydable et son procédé de fabrication. Le tuyau en acier inoxydable selon la présente invention présente : une composition de composant contenant, en % en masse, 0,05 % ou moins de C, 1,0 % ou moins de Si, 0,10 à 2,0 % de Mn, 0,05 % ou moins de P, moins de 0,005 % de S, plus de 16,0 % mais pas plus de 20,0 % de Cr, plus de 0,6 % mais moins de 1,4 % de Mo, 3,0 % ou plus mais moins de 5,0 % de Ni, 0,001 à 0,10 % d'Al, 0,010 à 0,100 % de N, 0,01 % ou moins de O, 0,3 à 3,5 % de Cu, et le reste étant du Fe et des impuretés inévitables, Cr, Ni, Mo, W, Cu et C satisfaisant une expression relationnelle prescrite ; une structure comprenant, en fraction volumique, 45 % ou plus de phase de martensite revenue, 20 à 40 % de phase ferrite et 5 % à 25 % de phase d'austénite maintenue ; une limite d'élasticité de 758 MPa ou plus ; et une énergie absorbée vE-10 de 40 J ou plus à -10 °C.
PCT/JP2022/011814 2021-04-21 2022-03-16 Tuyau en acier inoxydable et son procédé de fabrication WO2022224640A1 (fr)

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WO2010050519A1 (fr) 2008-10-30 2010-05-06 住友金属工業株式会社 Tuyau en acier inoxydable à haute limite élastique présentant une résistance élevée à la corrosion fissurante en présence d'hydrogène sulfuré et une résistance à la corrosion en présence de dioxyde de carbone à haute température
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JP2017039998A (ja) * 2015-08-18 2017-02-23 Ｊｆｅスチール株式会社 油井用継目無ステンレス鋼管およびその製造方法
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JP2019073789A (ja) 2017-10-19 2019-05-16 新日鐵住金株式会社 ステンレス鋼材及びステンレス鋼管

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