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WO2025187217A1 - Tuyau en acier inoxydable et tuyau de puits de pétrole - Google Patents

Tuyau en acier inoxydable et tuyau de puits de pétrole

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Publication number
WO2025187217A1
WO2025187217A1 PCT/JP2025/001369 JP2025001369W WO2025187217A1 WO 2025187217 A1 WO2025187217 A1 WO 2025187217A1 JP 2025001369 W JP2025001369 W JP 2025001369W WO 2025187217 A1 WO2025187217 A1 WO 2025187217A1
Authority
WO
WIPO (PCT)
Prior art keywords
less
stainless steel
steel pipe
kam
average
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/JP2025/001369
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English (en)
Japanese (ja)
Other versions
WO2025187217A8 (fr
Inventor
晃英 松本
祐一 加茂
健一郎 江口
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JFE Steel Corp
Original Assignee
JFE Steel Corp
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Filing date
Publication date
Application filed by JFE Steel Corp filed Critical JFE Steel Corp
Publication of WO2025187217A1 publication Critical patent/WO2025187217A1/fr
Publication of WO2025187217A8 publication Critical patent/WO2025187217A8/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • 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
    • 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
    • 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
    • C22C38/60—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 stainless steel pipes suitable for use in oil country tubular goods, and to oil country tubular goods.
  • Patent Document 1 proposes a martensitic stainless steel seamless pipe with enhanced corrosion resistance by controlling the amount of added elements so that the amount of retained austenite, repassivation potential, and pitting potential fall within appropriate ranges.
  • Patent Document 2 proposes a duplex stainless steel pipe with improved corrosion resistance by controlling the distribution of austenite and ferrite.
  • Patent No. 6315159 Japanese Patent Application Laid-Open No. 2022-111733
  • Patent Documents 1 and 2 above may not provide sufficient hydrogen embrittlement resistance, leaving room for improvement in hydrogen embrittlement resistance.
  • the present invention was made in consideration of the above circumstances, and aims to provide a stainless steel pipe that has high strength and excellent resistance to hydrogen embrittlement.
  • excellent hydrogen embrittlement resistance means that in a tensile test under hydrogen charging, which will be described later, the fracture elongation is 9.0% or more, and in the tensile test, when the horizontal axis is true strain and the vertical axis is true stress and the true strain at the maximum load is ⁇ max , the rate of change d2 ⁇ / d ⁇ 2 of the work hardening rate d ⁇ /d ⁇ with respect to ⁇ is -200,000 MPa or more in the range of true strain 0.8 ⁇ max to ⁇ max .
  • ⁇ is the true stress (MPa)
  • ⁇ is the true strain (no unit).
  • high strength refers to a yield strength of 450 MPa or more.
  • the present invention has been completed based on the above findings and comprises the following gist.
  • the steel structure at the center of the wall thickness is The total volume fraction of ferrite and martensite is 30% or more and 99% or less, the volume fraction of the ⁇ phase is 0% or more and 3% or less, and the remainder is austenite, an average KAM (Kernel Average Misorientation) value, which is an average of the KAM values of the steel structure, is 2.0° or more and 4.0° or less; A stainless steel pipe in which the standard deviation of the KAM value distribution is 1.5° or less.
  • KAM Kernel Average Misorientation
  • the stainless steel pipe is a seamless steel pipe.
  • [4] An oil well tubular good using the stainless steel pipe according to any one of [1] to [3] above.
  • the present invention makes it possible to provide stainless steel pipes and oil country tubular goods that have high strength and excellent resistance to hydrogen embrittlement.
  • the stainless steel pipe of the present invention is described below.
  • the total volume fraction of ferrite and martensite is 30% to 99%, the volume fraction of ⁇ phase is 0% to 3%, and the remainder is austenite.
  • the average KAM (Kernel Average Misorientation) value which is the average of the KAM values, is 2.0° to 4.0°, and the standard deviation of the KAM value distribution is 1.5° or less.
  • volume ratio will also be referred to as "fraction.”
  • the total volume fraction of ferrite and martensite is 30% or more.
  • the total volume fraction of ferrite and martensite is more preferably 35% or more, even more preferably 37% or more, and most preferably 40% or more. If the total volume fraction of ferrite and martensite is more than 99%, the amount of austenite will decrease and corrosion resistance will decrease. Therefore, it is preferable that the total volume fraction of ferrite and martensite is 99% or less.
  • the total volume fraction of ferrite and martensite is more preferably 95% or less, even more preferably 93% or less, and most preferably 90% or less.
  • the ⁇ phase is an intermetallic compound that reduces the corrosion resistance and toughness of stainless steel, and because it reduces the fracture elongation and d2 ⁇ / d ⁇ 2 under hydrogen charging, a small amount is preferable.
  • the volume fraction of the ⁇ phase is 0% or more and 3% or less.
  • the volume fraction of the ⁇ phase is 3% or less, preferably 2% or less, more preferably 1% or less, and even more preferably 0%.
  • the volume fractions of austenite and ⁇ phase are determined using the SEM/EBSD method.
  • the measurement surface is a cross section parallel to both the wall thickness direction and the axial direction of the tube.
  • the measurement area (one field of view) is 400 ⁇ m x 400 ⁇ m, the measurement step size is 0.1 ⁇ m, and the measured values for five fields of view are averaged.
  • a phase distribution diagram is obtained using crystal orientation analysis software OIM Analysis (trademark).
  • OIM Analysis trademark
  • the area fraction of ferrite is determined by subtracting the area fractions of austenite and ⁇ phase determined by SEM/EBSD from the total area fraction of ferrite, austenite, and ⁇ phase.
  • the area fractions of ferrite and martensite determined in this manner are taken as their respective volume fractions.
  • the average KAM value is preferably 2.1° or more, more preferably 2.2° or more, even more preferably 2.3° or more, and most preferably 2.4° or more.
  • the average KAM value exceeds 4.0°, the amount of hard martensite with a high dislocation density and work-hardened structures increases, and the fracture elongation and d2 ⁇ / d ⁇ 2 under hydrogen charging decrease. Therefore, the average KAM value is 4.0° or less.
  • the average KAM value is preferably 3.9° or less, more preferably 3.8° or less, even more preferably 3.7° or less, and most preferably 3.6° or less.
  • Standard deviation of KAM value distribution 1.5° or less If the variation in KAM values is large, soft and hard parts are mixed and the difference in hardness between them becomes large, so stress concentrates at the interface between them, becoming the starting point for cracks, and breaking elongation under hydrogen charging decreases. Therefore, the standard deviation of the KAM value distribution is 1.5° or less.
  • the standard deviation of the KAM value distribution is preferably 1.4° or less, more preferably 1.3° or less, even more preferably 1.2° or less, and most preferably 1.1° or less.
  • the average KAM value and standard deviation of the KAM value distribution are measured using the SEM/EBSD method.
  • the measurement area (one field of view) is 400 ⁇ m x 400 ⁇ m, the measurement step size is 0.1 ⁇ m, and the measured values for five fields of view are averaged.
  • a distribution image of KAM values (KAM map) is obtained using the crystal orientation analysis software OIM Analysis (trademark).
  • the KAM value is calculated using the following method. At each measurement point (a regular hexagonal pixel), the orientation difference between each pixel is calculated using the center and the three neighboring pixels (37 pixels in total), and the average of the calculated orientation differences is used as the KAM value of the central pixel. This operation is performed for all pixels in the field of view to obtain a KAM map. From the obtained KAM value distribution, the average KAM value and the standard deviation of the KAM value distribution are calculated using equations (1) and (2), respectively.
  • the composition of the stainless steel pipe of the present invention is, in mass%, C: 0.060% or less, Si: 1.00% or less, Mn: 6.00% or less, P: 0.050% or less, S: 0.0300% or less, Al: 0.005% or more and 0.100% or less, N: 0.400% or less, Cr: 11.00% or more and 30.00% or less, Mo: 5.00% or less, Ni: 15.00% or less, and optionally Cu: 4.00% or less, V: 0.300% or less, Nb: 0.300% or less, T It is preferable that the steel sheet contains one or more elements selected from the group consisting of i: 0.300% or less, B: 0.0050% or less, W: 3.00% or less, Ca: 0.0050% or less, Co: 0.500% or less, Sn: 0.100% or less, Mg: 0.020% or less, Zr: 0.020% or less, REM: 0.020% or less, Ta: 0.10% or less, and Sb: 0.100%
  • C 0.060% or less
  • C is an element that increases the strength of steel through solid solution strengthening. Furthermore, C refines crystal grains by lowering the transformation start temperature, thereby increasing the strength of steel. It also stabilizes austenite and increases the austenite and martensite fractions. To achieve these effects, it is preferable to contain 0.002% or more of C. More preferably, it is 0.003% or more, even more preferably 0.004% or more, and most preferably 0.005% or more. However, excessive C content forms Cr carbides at grain boundaries, increasing corrosion susceptibility at the grain boundaries and reducing hydrogen embrittlement resistance. Therefore, the C content is preferably 0.060% or less. The C content is more preferably 0.050% or less, even more preferably 0.040% or less, and most preferably 0.035% or less.
  • Si 1.00% or less
  • Si is an element that acts as a deoxidizer and also stabilizes ferrite, increasing the ferrite fraction. To achieve this effect, it is desirable to contain 0.01% or more of Si.
  • the Si content is more preferably 0.05% or more, even more preferably 0.07% or more, and most preferably 0.10% or more.
  • the Si content is preferably 1.00% or less.
  • the Si content is more preferably 0.90% or less, even more preferably 0.80% or less, and most preferably 0.70% or less.
  • Mn 6.00% or less
  • Mn is an element that increases the strength of steel through solid solution strengthening. Furthermore, Mn refines crystal grains by lowering the transformation start temperature, thereby increasing the strength of steel. It also stabilizes austenite and increases the austenite and martensite fractions. To achieve these effects, it is preferable to contain 0.05% or more of Mn.
  • the Mn content is more preferably 0.10% or more, even more preferably 0.15% or more, and most preferably 0.20% or more. However, excessive Mn content increases the strength of the steel too much, resulting in reduced hydrogen embrittlement resistance. Therefore, the Mn content is preferably 6.00% or less.
  • the Mn content is more preferably 5.00% or less, even more preferably 3.00% or less, and most preferably 2.50% or less.
  • P 0.050% or less Since P segregates at grain boundaries and reduces toughness, it is preferable to reduce P as an unavoidable impurity as much as possible, and the P content is preferably in the range of 0.050% or less.
  • the P content is more preferably 0.040% or less, even more preferably 0.030% or less, and most preferably 0.025% or less.
  • P is preferably 0.001% or more.
  • P is more preferably 0.002% or more, and even more preferably 0.003% or more.
  • S 0.0300% or less
  • S is an element that significantly deteriorates hot workability during the pipe manufacturing process, so it is desirable to keep the content as low as possible.
  • S is preferably set to 0.0300% or less.
  • the S content is more preferably 0.0100% or less, even more preferably 0.0050% or less, and most preferably 0.0030% or less.
  • S is preferably set to 0.0001% or more.
  • S is more preferably 0.0002% or more, and even more preferably 0.0003% or more.
  • Al 0.005% or more and 0.100% or less
  • Al is an element that acts as a powerful deoxidizer. It also stabilizes ferrite and increases the ferrite fraction. To achieve this effect, it is preferable to contain 0.005% or more of Al.
  • the Al content is more preferably 0.010% or more, even more preferably 0.015% or more, and most preferably 0.018% or more.
  • the Al content is preferably 0.100% or less.
  • the Al content is more preferably 0.080% or less, even more preferably 0.070% or less, and most preferably 0.065% or less.
  • N 0.400% or less
  • N has the effect of improving hydrogen embrittlement resistance. It is also an element that stabilizes austenite and increases the austenite fraction and martensite fraction. To achieve this effect, it is preferable to contain 0.002% or more of N.
  • the N content is more preferably 0.005% or more, even more preferably 0.010% or more, and most preferably 0.020% or more.
  • the N content exceeds 0.400%, hot workability deteriorates.
  • nitrides are formed at grain boundaries, which deteriorates hydrogen embrittlement resistance. For this reason, the N content is preferably 0.400% or less.
  • the N content is more preferably 0.380% or less, even more preferably 0.360% or less, and most preferably 0.340% or less.
  • Cr 11.00% or more and 30.00% or less Cr forms a protective film on the surface of the steel, suppressing hydrogen penetration into the steel and improving hydrogen embrittlement resistance. It also stabilizes ferrite and increases the ferrite fraction. If the Cr content is less than 11.00%, corrosion resistance will be insufficient, and the hydrogen embrittlement resistance desired by the present invention will not be ensured. Therefore, the Cr content is set to 11.00% or more.
  • the Cr content is preferably 11.20% or more, more preferably 11.50% or more, even more preferably 11.70% or more, and most preferably 11.90% or more.
  • the Cr content is set to 30.00% or less.
  • the Cr content is preferably 28.00% or less, more preferably 26.00% or less, and even more preferably 24.00% or less. The most preferable content is 20.00% or less.
  • Mo 5.00% or less
  • Mo has the effect of stabilizing the protective film on the steel surface, suppressing hydrogen penetration into the steel, and improving hydrogen embrittlement resistance. It is also an element that stabilizes ferrite and increases the ferrite fraction. To achieve this effect, it is preferable to contain 0.01% or more of Mo.
  • the Mo content is more preferably 0.05% or more, even more preferably 0.10% or more, and most preferably 0.15% or more.
  • the Mo content is preferably 5.00% or less.
  • the Mo content is more preferably 4.50% or less, even more preferably 4.30% or less, and most preferably 4.00% or less.
  • Ni 15.00% or less
  • Ni has the effect of stabilizing the protective film on the steel surface, suppressing hydrogen penetration into the steel, and improving hydrogen embrittlement resistance. It is also an element that stabilizes austenite and increases the austenite fraction and martensite fraction. To achieve this effect, a Ni content of 0.01% or more is preferable.
  • the Ni content is more preferably 1.00% or more, even more preferably 3.00% or more, and most preferably 3.50% or more.
  • the Ni content is preferably 15.00% or less.
  • the Ni content is more preferably 10.00% or less, even more preferably 9.00% or less, and most preferably 8.50% or less.
  • one or more elements selected from Cu, V, Nb, Ti, B, W, Ca, Co, Sn, Mg, Zr, REM, Ta, and Sb can be optionally selected.
  • Cu stabilizes the protective coating on the steel surface, inhibits hydrogen penetration into the steel, and enhances hydrogen embrittlement resistance. It also stabilizes austenite, increasing the austenite and martensite fractions. To achieve this effect, a Cu content of 0.01% or more is desirable.
  • the Cu content is more preferably 0.05% or more, even more preferably 0.10% or more, most preferably 0.20% or more, and most preferably 0.30% or more.
  • a Cu content exceeding 4.00% leads to grain boundary precipitation of CuS, degrading hot workability. Therefore, when Cu is contained, the Cu content is set to 4.00% or less.
  • the Cu content is preferably 3.50% or less, more preferably 3.00% or less, even more preferably 2.80% or less, and most preferably 2.50% or less.
  • V 0.300% or less
  • Nb 0.300% or less
  • Ti 0.300% or less.
  • V, Nb, and Ti are elements that contribute to improving the strength of steel by forming fine carbides and nitrides in the steel. They also have the effect of improving hydrogen embrittlement resistance by trapping hydrogen atoms when hydrogen generated by corrosion penetrates the steel. V and Ti also stabilize ferrite and increase the ferrite fraction. To achieve the above effects, it is preferable to contain V: 0.002% or more, Nb: 0.002% or more, and Ti: 0.002% or more, respectively. More preferably, V: 0.005% or more, Nb: 0.005% or more, and Ti: 0.005% or more.
  • V 0.010% or more
  • Nb 0.010% or more
  • Ti 0.010% or more
  • V is 0.015% or more
  • Nb is 0.015% or more
  • Ti is 0.015% or more.
  • the V content is set to 0.300% or less
  • Nb is 0.300% or less
  • Ti is 0.300% or less.
  • V is 0.200% or less
  • Nb is 0.200% or less
  • Ti is 0.200% or less.
  • V is 0.150% or less
  • Nb is 0.150% or less
  • Ti is 0.150% or less.
  • V is 0.140% or less
  • Nb is 0.140% or less
  • Ti is 0.140% or less
  • V is 0.120% or less
  • Nb is 0.120% or less
  • Ti is 0.120% or less.
  • B 0.0050% or less
  • B is an element that contributes to refining the structure by lowering the transformation start temperature and increases the strength of the steel. It also has the effect of suppressing grain boundary segregation of S and improving hot workability.
  • it is preferable to contain 0.0002% or more of B. More preferably, it is 0.0005% or more, even more preferably, it is 0.0008% or more, and most preferably, it is 0.0010% or more.
  • excessive B content forms nitrides at grain boundaries, which reduces hydrogen embrittlement resistance. Therefore, when B is contained, the B content is set to 0.0050% or less. It is preferably 0.0045% or less, preferably 0.0040% or less, more preferably, it is 0.0035% or less, even more preferably, it is 0.0030% or less, and most preferably, it is 0.0025% or less.
  • W 3.00% or less
  • W is an element that contributes to improving the strength of steel through solid solution strengthening and stabilizes the protective film on the steel surface, thereby enhancing hydrogen embrittlement resistance. It also stabilizes ferrite and increases the ferrite fraction.
  • excessive W content reduces toughness by forming intermetallic compounds. Therefore, when W is contained, the W content is set to 3.00% or less. It is preferably 2.50% or less, more preferably, it is 2.40% or less, even more preferably, it is 2.20% or less, and most preferably, it is 2.00% or less.
  • Ca is an element that can improve hydrogen embrittlement resistance by spheroidizing sulfides such as MnS. To achieve the above-mentioned effects, it is preferable to contain 0.0005% or more of Ca. More preferably, it is 0.0008% or more, even more preferably, it is 0.0010% or more, and most preferably, it is 0.0012% or more. However, if it is contained in excess, Ca oxide clusters are formed in the steel, which deteriorates toughness. Therefore, when Ca is contained, the Ca content is set to 0.0050% or less. It is preferably 0.0040% or less, more preferably, it is 0.0035% or less, even more preferably, it is 0.0030% or less, and most preferably, it is 0.0025% or less.
  • Co 0.500% or less Co stabilizes the protective coating on the steel surface, inhibits hydrogen penetration into the steel, and enhances hydrogen embrittlement resistance. It also stabilizes austenite, increasing the austenite and martensite fractions. To achieve the above-mentioned effects, it is preferable to contain 0.002% or more of Co. More preferably, it is 0.005% or more, even more preferably 0.010% or more, and most preferably 0.015% or more. However, if the content exceeds 0.500%, the obtained effects saturate and only increase manufacturing costs. Therefore, if Co is contained, the Co content is set to 0.500% or less. It is preferably 0.450% or less, more preferably 0.400% or less, even more preferably 0.0300% or less, and most preferably 0.200% or less.
  • Sn 0.100% or less Sn stabilizes the protective film on the steel surface, inhibits hydrogen penetration into the steel, and enhances hydrogen embrittlement resistance. To achieve the above-mentioned effects, it is preferable to contain 0.001% or more of Sn. More preferably, it is 0.002% or more, and even more preferably, it is 0.005% or more. However, if it contains more than 0.100%, hot workability deteriorates. Therefore, when Sn is contained, the Sn content is set to 0.100% or less. It is preferably 0.070% or less, more preferably 0.050% or less, even more preferably 0.040% or less, and most preferably 0.030% or less.
  • Mg 0.020% or less Mg has the effect of improving hydrogen embrittlement resistance through morphology control of inclusions. To obtain the above effect, it is preferable to contain 0.001% or more of Mg. More preferably, it is 0.002% or more, and even more preferably, it is 0.005% or more. However, if it contains more than 0.020%, hot workability decreases. Therefore, when Mg is contained, the Mg content is set to 0.020% or less. It is preferably 0.015% or less, more preferably 0.010% or less, even more preferably 0.009% or less, and most preferably 0.008% or less.
  • Zr 0.020% or less
  • Zr is an element that contributes to improving the strength of steel by forming fine carbides and nitrides in the steel.
  • the Zr content is set to 0.020% or less. It is preferably 0.015% or less, more preferably 0.010% or less, even more preferably 0.009% or less, and most preferably 0.008% or less.
  • REM 0.020% or less REM has the effect of improving hydrogen embrittlement resistance through morphology control of inclusions. To achieve the above effect, it is preferable to contain 0.001% or more of REM. More preferably, it is 0.002% or more, even more preferably, it is 0.005% or more, and most preferably, it is 0.006% or more. However, if it contains more than 0.020%, hot workability decreases. Therefore, when REM is contained, the REM content is set to 0.020% or less. It is preferably 0.015% or less, more preferably, it is 0.010% or less, even more preferably, it is 0.009% or less, and most preferably, it is 0.008% or less.
  • REM is a general term for Sc, Y, and lanthanoid elements, a total of 17 elements, and the REM content means the total content of these elements.
  • Ta 0.10% or less
  • Ta is an element that contributes to improving the strength of steel by forming fine carbides and nitrides in the steel.
  • the Ta content is set to 0.10% or less. It is preferably 0.08% or less, more preferably 0.07% or less, even more preferably 0.06% or less, and most preferably 0.05% or less.
  • Sb 0.100% or less Sb stabilizes the protective film on the steel surface, inhibits hydrogen penetration into the steel, and enhances hydrogen embrittlement resistance. To achieve the above-mentioned effects, it is preferable to contain 0.001% or more of Sb. More preferably, it is 0.002% or more, even more preferably, it is 0.005% or more, and most preferably, it is 0.008% or more. However, if it is contained in excess of 0.100%, hot workability deteriorates. Therefore, when Sb is contained, the Sb content is set to 0.100% or less. It is preferably 0.070% or less, more preferably, it is 0.050% or less, even more preferably, it is 0.040% or less, and most preferably, it is 0.030% or less.
  • the balance is Fe and unavoidable impurities.
  • unavoidable impurities in the balance include As, Bi, Pb, Zn, O, Te, Hf, Ge, Sr, and Cs. However, this does not exclude the inclusion of 0.10% or less of As, Te, Hf, Ge, Sr, and Cs, and 0.005% or less of Bi, Pb, Zn, and O, as long as the effects of this invention are not impaired.
  • the stainless steel pipe of the present invention has a fracture elongation of 9.0% or more when subjected to a tensile test under cathodic hydrogen charging, and when the true strain at the maximum load is ⁇ max , the rate of change of the work hardening rate d ⁇ /d ⁇ relative to ⁇ , d 2 ⁇ /d ⁇ 2 , is -200,000 MPa or more in the range of true strain from 0.8 ⁇ max to ⁇ max , where ⁇ is true stress (MPa) and ⁇ is true strain (unitless).
  • Figure 1 shows a schematic diagram of a curve plotting true strain ⁇ on the horizontal axis and true stress ⁇ on the vertical axis when a tensile test was conducted under cathodic hydrogen charging.
  • true strain 0.8 ⁇ max or more and ⁇ max or less
  • the mode changes from elastic deformation (elastic region) to plastic deformation (plastic region), and this is the stage generally referred to as uniform elongation.
  • the range of 0.8 ⁇ max or more and ⁇ max or less is focused on and limited to the above.
  • the above-mentioned range is basically focused on, but it may also be 0.9 ⁇ max or more.
  • Stainless steel pipes that have the above properties have excellent resistance to hydrogen embrittlement.
  • the hydrogen charging is carried out by cathodic hydrogen charging at a current density of 0.05 mA/ cm2 for 24 hours in a solution at room temperature (21 to 27°C) in which 3.0 g of ammonium thiocyanate is added per 1 L of a 3.0 mass% aqueous sodium chloride solution. Thereafter, a tensile test is carried out while continuing cathodic hydrogen charging under the same conditions.
  • the hydrogen charging method is not limited to the above method, and any condition that results in the hydrogen content in the steel at the time of fracture in the tensile test being 1.5 mass ppm or more is sufficient. Conditions that result in a hydrogen content of 1.6 mass ppm or more are more preferable, and conditions that result in a hydrogen content of 1.7 mass ppm or more are even more preferable. There is no particular upper limit, but it is preferable that the hydrogen content be 10.0 mass ppm or less.
  • the hydrogen content in the steel is measured, for example, by thermal desorption, with a heating rate of 100°C/s, the temperature raised to 600°C, and a gas chromatograph used as the analyzer.
  • the strain rate in the tensile test is, for example, 1.7 ⁇ 10 ⁇ 5 s ⁇ 1 .
  • the strain rate in the tensile test is not particularly limited, but is preferably 1.0 ⁇ 10 ⁇ 5 s ⁇ 1 or more, more preferably 1.5 ⁇ 10 ⁇ 5 s ⁇ 1 or more, even more preferably 1.8 ⁇ 10 ⁇ 5 s ⁇ 1 or more, and most preferably 1.9 ⁇ 10 ⁇ 5 s ⁇ 1 or more.
  • the strain rate is preferably 9.0 ⁇ 10 ⁇ 5 s ⁇ 1 or less, and more preferably 6.0 ⁇ 10 ⁇ 5 s ⁇ 1 or less.
  • round bar test specimens with a parallel section diameter of 3.8 mm and a parallel section length of 15 mm are used.
  • the test specimens are taken from the center of the wall thickness so that the tensile direction is parallel to the tube axis.
  • Breaking elongation 9.0% or more If the breaking elongation in the tensile test under hydrogen charging described above is small, the ductility in a hydrogen environment will be insufficient. Therefore, in the present invention, the breaking elongation is set to 9.0% or more. It is preferably 9.5% or more, more preferably 10.0% or more, even more preferably 10.2% or more, and most preferably 10.4% or more. The greater the breaking elongation, the better, but an excessive increase in breaking elongation will lead to increased manufacturing costs and manufacturing load, so the breaking elongation is preferably 30.0% or less. More preferably, it is 28.0% or less. Even more preferably, it is 25.0% or less, and most preferably, it is 24.0% or less. The breaking elongation (%) is calculated by ((total length when the test pieces are butted together after the test) - (total length of the test piece before the test))/(total length of the test piece before the test) x 100.
  • d 2 ⁇ /d ⁇ 2 When the true strain is in the range of 0.8 ⁇ max to ⁇ max , d 2 ⁇ /d ⁇ 2 is ⁇ 200,000 MPa or more. While work hardening progresses in the plastic region, the work hardening rate d ⁇ /d ⁇ decreases with an increase in ⁇ . That is, d 2 ⁇ /d ⁇ 2 takes a negative value. The smaller d 2 ⁇ /d ⁇ 2 is, the more rapidly d ⁇ /d ⁇ decreases, causing necking to occur earlier, reducing the maximum load and lowering ductility. In particular, it is important to control the true strain within a range of 0.8 ⁇ max or more and ⁇ max or less.
  • d 2 ⁇ /d ⁇ 2 in the tensile test under hydrogen charging is set to -200,000 MPa or more. It is preferably -180,000 MPa or more, more preferably -160,000 MPa or more, even more preferably -150,000 MPa or more, and most preferably -140,000 MPa or more.
  • d 2 ⁇ /d ⁇ 2 is preferably less than 0 MPa, more preferably ⁇ 10,000 MPa or less, and even more preferably ⁇ 15,000 MPa or less.
  • d ⁇ /d ⁇ and d 2 ⁇ /d ⁇ 2 are determined from the time history data of the load and crosshead displacement in the tensile test.
  • ⁇ and ⁇ at each time are determined from the load and crosshead displacement.
  • ⁇ at a certain time t(s) is determined as the average value of ⁇ from time (t - 30) (s) to time (t + 30) (s). This is performed for all times.
  • d ⁇ /d ⁇ is determined at each time.
  • d ⁇ /d ⁇ at a certain time t(s) is determined as the average rate of change from time (t - 60) (s) to time t(s). This is performed for all times.
  • d 2 ⁇ /d ⁇ 2 is determined at each time. Specifically, (d/d ⁇ ) (d ⁇ /d ⁇ ) at a certain time t(s) is calculated as the average rate of change from time (t-60)(s) to time t(s). This is done for all times.
  • ⁇ is calculated from the crosshead displacement.
  • the value of ⁇ includes an error due to the elastic deformation of the testing machine.
  • d ⁇ /d ⁇ and d 2 ⁇ /d ⁇ 2 are calculated from the change in ⁇ , the error in the present invention is small enough to be ignored.
  • the stainless steel pipe of the present invention has a yield strength of 450 MPa or more.
  • it is 550 MPa or more, more preferably 580 MPa or more, and even more preferably 600 MPa or more.
  • the yield strength is preferably 1100 MPa or less. More preferably, it is 1000 MPa or less, even more preferably 990 MPa or less, and most preferably 980 MPa or less.
  • Yield strength is measured in air at room temperature (10-38°C) using a tensile test.
  • Test specimens are taken in accordance with ASTM E8/E8M (2021), with round bar test specimens taken from the center of the wall thickness so that the tensile direction is parallel to the pipe axis.
  • the size of the round bar test specimen is, for example, 8.9 mm in diameter at the parallel part and 35.6 mm gauge length. If round bar test specimens cannot be taken from the steel pipe, arc test specimens are taken.
  • the size of the arc test specimen is, for example, the full wall thickness, 25.4 mm in width, and 50.8 mm gauge length.
  • a tensile test is performed using the taken tensile test specimen in accordance with ASTM E8/E8M (2021). The obtained 0.2% offset yield strength (MPa) is taken as the yield strength (MPa).
  • the aforementioned stainless steel pipes are seamless steel pipes.
  • the oil well tubular goods are made of the above-mentioned stainless steel pipes.
  • the stainless steel pipe of the present invention is manufactured, for example, by heating and hot-working a steel material having the above-described chemical composition into a cylindrical shape, cooling it, and then subjecting it to heat treatment.
  • temperatures indicated in “°C” refer to surface temperatures unless otherwise specified. These surface temperatures can be measured using a radiation thermometer or similar. The temperature at the center of the wall thickness can be determined by calculating the temperature distribution in the wall thickness direction using heat transfer analysis and correcting the results for the surface temperature.
  • the method for melting steel material there are no particular restrictions on the method for melting steel material, and any known melting method such as a converter, electric furnace, or vacuum melting furnace is suitable.
  • the casting method is also not particularly limited, and steel can be produced to the desired dimensions using a known casting method such as continuous casting. Note that there is no problem with using an ingot-blooming rolling method instead of continuous casting.
  • the molten steel may also be subjected to secondary refining such as ladle refining. It is preferable to cast the steel material into a round bar shape such as a billet, which is then used as steel pipe material, but the cast slab may also be further hot-rolled to the desired dimensions and shape, and used as steel pipe material.
  • the resulting steel pipe material is then heated and hot-worked to produce a stainless steel pipe of the desired shape.
  • the hot pipe-making process is preferably a Mannesmann plug mill or Mannesmann mandrel mill hot pipe-making process.
  • stainless steel pipe may also be produced by hot extrusion using a press method. There are no particular requirements for the hot pipe-making process, as long as it can produce a stainless steel pipe of the desired shape.
  • the heating temperature of the steel pipe material is preferably in the range of 1100 to 1350°C.
  • a heating temperature below 1100°C reduces the hot workability of the billet, making it more susceptible to defects during pipe making. It also places an excessive load on the equipment. Therefore, the heating temperature is preferably 1100°C or higher.
  • the heating temperature is more preferably 1150°C or higher, even more preferably 1160°C or higher, and most preferably 1170°C or higher.
  • the heating temperature in the heating process is preferably 1350°C or lower.
  • the heating temperature is more preferably 1300°C or lower, even more preferably 1290°C or lower, and most preferably 1280°C or lower.
  • the area reduction rate (%) of the cross section perpendicular to the pipe axis direction be 25% or more.
  • the area reduction rate (%) is calculated by ((cross-sectional area of steel pipe material) - (cross-sectional area after hot pipe-making)) / (cross-sectional area of steel pipe material) x 100. If the area reduction rate is small, the crystal grains will coarsen, the variation in KAM values within the crystal grains will increase, and the standard deviation of the KAM value distribution will increase.
  • the area reduction rate is more preferably 30% or more, even more preferably 35% or more, and most preferably 40% or more.
  • the area reduction rate be 75% or less. More preferably, it is 70% or less, even more preferably 65% or less, and most preferably 60% or less.
  • the resulting stainless steel pipe is subjected to a cooling treatment.
  • the average cooling rate at the center of the wall thickness in the range of 650 to 300°C is 10°C/s or more, and the minimum cooling rate is 3°C/s or more.
  • the minimum cooling rate is calculated by dividing the time in the range of 650 to 300°C into 3-second intervals, calculating the average cooling rate in each interval, and then taking the minimum value of these.
  • the average cooling rate in each interval can be calculated by subtracting the cooling end temperature from the cooling start temperature in a given interval and dividing the result by the time required for cooling in that given interval.
  • the average cooling rate in the range of 650 to 300°C can be calculated by (650 - 300) / (time required for cooling in the range of 650 to 300°C) (°C/s). If the average cooling rate and minimum cooling rate are low, the crystal grains will coarsen, the variation in KAM values within the crystal grains will increase, and the standard deviation of the KAM value distribution will increase. Furthermore, the ⁇ phase, which is an embrittlement phase, will form, and the fracture elongation and d 2 ⁇ /d ⁇ 2 under hydrogen charging will decrease. Therefore, the average cooling rate in the range of 650 to 300°C is preferably 10°C/s or more. More preferably, it is 15°C/s or more.
  • the average cooling rate is preferably 100°C/s or less. More preferably, it is 70°C/s or less. Even more preferably, it is 60°C/s or less, and most preferably, it is 50°C/s or less.
  • the minimum cooling rate is preferably 3°C/s or more. The minimum cooling rate is more preferably 4°C/s or more, even more preferably, 5°C/s or more, and most preferably, 6°C/s or more.
  • the minimum cooling rate exceeds 15°C/s, the load on the cooling device becomes excessive, so the minimum cooling rate is preferably 15°C/s or less.
  • the minimum cooling rate is more preferably 12°C/s or less, even more preferably 11°C/s or less, and most preferably 10°C/s or less. Water cooling is preferred as the cooling method in order to ensure the required cooling rate.
  • the seamless steel pipe it is preferable to subject the seamless steel pipe to a heat treatment consisting of quenching and tempering.
  • a heat treatment consisting of quenching and tempering.
  • the Cr content is 20.00% or more, austenite is stable at room temperature and the martensite fraction is low, so tempering can be omitted.
  • the stainless steel pipe is reheated to a temperature (heating temperature) in the range of 850 to 1150°C and held at that temperature for at least 300 seconds.
  • the average cooling rate in the range of 650 to 300°C at the center of the wall thickness is set to 10°C/s or more, and the minimum cooling rate is set to 3°C/s or more.
  • the minimum cooling rate is determined by dividing the time in the range of 650 to 300°C into 3-second intervals, calculating the average cooling rate in each interval, and taking the minimum of these values.
  • the average cooling rate in each interval can be calculated by subtracting the cooling start temperature from the cooling end temperature for that interval and dividing the result by the time required for cooling in that interval.
  • the average cooling rate in the range of 650 to 300°C can be calculated by (650 - 300) / (time required for cooling in the range of 650 to 300°C) (°C/s).
  • the heating temperature for quenching is preferably 850°C or higher, more preferably 880°C or higher, even more preferably 900°C or higher, and most preferably 920°C or higher. If the heating temperature for quenching is high, the crystal grains will coarsen, increasing the variation in KAM values within the crystal grains and the standard deviation of the KAM value distribution. Therefore, the heating temperature for quenching is preferably 1150°C or lower, more preferably 1130°C or lower, even more preferably 1100°C or lower, and most preferably 1080°C or lower.
  • the average cooling rate in the range of 650 to 300°C is preferably 10°C/s or more. More preferably, it is 15°C/s or more. Even more preferably, it is 18°C/s or more, and most preferably, it is 20°C/s or more. If the average cooling rate exceeds 100°C/s, the load on the cooling device becomes excessive, so the average cooling rate is preferably 100°C/s or less.
  • the minimum cooling rate is preferably 3°C/s or more.
  • the minimum cooling rate is more preferably 4°C/s or more, even more preferably, 5°C/s or more, and most preferably, it is 6°C/s or more. If the minimum cooling rate exceeds 15°C/s, the load on the cooling device becomes excessive, so the minimum cooling rate is preferably 15°C/s or less.
  • the cooling rate is more preferably 12° C./s or less, even more preferably 11° C./s or less, and most preferably 10° C./s or less.
  • the cooling method is preferably water cooling in order to ensure the necessary cooling rate.
  • stainless steel pipes that have been quenched be subsequently tempered.
  • the material is heated to 500°C or higher and 750°C or lower, preferably held for 30 minutes or longer, and then cooled, preferably to room temperature, at a cooling rate faster than air cooling. If the heating temperature in the tempering treatment is low, dislocation recovery does not proceed sufficiently, resulting in increased variation in the KAM values within the crystal grains and a larger standard deviation in the KAM value distribution. Therefore, the heating temperature in the tempering treatment is preferably 500°C or higher, more preferably 550°C or higher, even more preferably 560°C or higher, and most preferably 570°C or higher.
  • the heating temperature in the tempering treatment is preferably 750°C or lower, more preferably 720°C or lower.
  • the temperature is more preferably 700°C or lower, and most preferably 680°C or lower.
  • cold working may be performed following tempering to correct defects in the steel pipe shape or to adjust the yield strength through work hardening.
  • cold working methods include cold drawing. If the area reduction rate (%) of the cross section perpendicular to the pipe axis direction during cold working exceeds 40%, work hardening will increase, resulting in a high average KAM value. Therefore, the area reduction rate (%) during cold working is preferably 40% or less. More preferably, it is 35% or less. Even more preferably, it is 30% or less, and most preferably, it is 25% or less. Furthermore, although there is no particular lower limit, it is preferable that the area reduction rate (%) during cold working be 5% or more.
  • the area reduction rate (%) during cold working is calculated by ((cross-sectional area before working) - (cross-sectional area after working)) / (cross-sectional area before working) x 100.
  • Molten steel having the chemical composition shown in Table 1 was melted and made into billets (steel pipe materials). The resulting billets were heated and hot worked under the conditions shown in Table 2, and then cooled to obtain stainless steel pipes having the outer diameters (mm) and wall thicknesses (mm) shown in Table 2.
  • Test pieces were taken from the obtained stainless steel pipe and the following KAM value measurements, tensile tests, and tensile tests under cathodic hydrogen charging were carried out. Note that the microstructural evaluation was carried out based on the details explained in the embodiment.
  • KAM value measurement The average KAM value and the standard deviation of the KAM value distribution were measured using the SEM/EBSD method.
  • the acceleration voltage was 15 kV.
  • the measurement area (one field of view) was 400 ⁇ m ⁇ 400 ⁇ m, the measurement step size was 0.1 ⁇ m, and the measured values of five fields of view were averaged.
  • a distribution image of KAM values (KAM map) was obtained using crystal orientation analysis software OIM Analysis (trademark).
  • the KAM value was calculated using the following method. At each measurement point (a regular hexagonal pixel), the orientation difference between each pixel was calculated using the center and the three neighboring pixels (37 pixels in total), and the average of the calculated orientation differences was used as the KAM value of the central pixel. This operation was performed for all pixels in the field of view to obtain a KAM map. From the obtained KAM value distribution, the average KAM value and the standard deviation of the KAM value distribution were calculated using equations (1) and (2), respectively.
  • Test specimens were prepared in accordance with ASTM E8/E8M (2021), with arc-shaped specimens prepared so that the tensile direction was parallel to the pipe axis.
  • the arc-shaped specimens had a thickness equal to the full wall thickness, a width of 25.4 mm, and a gauge length of 50.8 mm.
  • Tensile tests were performed using the prepared tensile test specimens in accordance with ASTM E8/E8M (2021). The obtained 0.2% offset yield strength (MPa) was taken as the yield strength (MPa).
  • d ⁇ /d ⁇ and d 2 ⁇ /d ⁇ 2 were determined from the time history data of the load and crosshead displacement in the tensile test.
  • ⁇ and ⁇ at each time were determined from the load and crosshead displacement.
  • ⁇ at a certain time t (s) was determined as the average value of ⁇ from time (t - 30) (s) to time (t + 30) (s). This was performed for all times.
  • d ⁇ /d ⁇ was determined at each time.
  • d ⁇ /d ⁇ at a certain time t (s) was determined as the average rate of change from time (t - 60) (s) to time t (s). This was performed for all times.
  • d 2 ⁇ /d ⁇ 2 was determined at each time. Specifically, (d/d ⁇ ) (d ⁇ /d ⁇ ) at a certain time t(s) was calculated as the average rate of change from time (t-60)(s) to time t(s). This was done for all times.
  • stainless steel pipes No. 1, 3, 5, 8, 10, 12, 15, 16, 17, 20, 26, and 27 are examples of the present invention, and stainless steel pipes No. 2, 4, 6, 7, 9, 11, 13, 14, 18, 19, and 21 to 25 are comparative examples.
  • the stainless steel pipes of the present invention all had a steel structure at the center of the wall thickness in which the total volume fraction of ferrite and martensite was 30% to 99%, the volume fraction of the ⁇ phase was 0% to 3%, and the remainder was austenite, and the average KAM value was 2.0° to 4.0°, and the standard deviation of the KAM value distribution was 1.5° or less. Furthermore, the yield strength was 450 MPa or more, the fracture elongation was 9.0% or more, and the rate of change of the work hardening rate d ⁇ /d ⁇ with respect to ⁇ , d 2 ⁇ /d ⁇ 2, was ⁇ 200,000 MPa or more within the true strain range of 0.8 ⁇ max to ⁇ max .
  • the stainless steel pipe of Comparative Example No. 2 had a large standard deviation in the KAM value distribution, and as a result, the breaking elongation required in the present invention was not obtained.
  • the stainless steel pipe of Comparative Example No. 4 had a large standard deviation in the KAM value distribution, and as a result, was unable to obtain the breaking elongation required in the present invention.
  • the stainless steel pipe No. 6 of the comparative example had a large standard deviation in the KAM value distribution, and as a result, the breaking elongation required in the present invention was not obtained.
  • the comparative stainless steel pipe No. 9 had a low average KAM value, and as a result, did not achieve the fracture elongation and d2 ⁇ / d ⁇ 2 required in the present invention. The yield strength also tended to be low.
  • the stainless steel pipe No. 11 of the comparative example had a large standard deviation in the KAM value distribution, and as a result, the breaking elongation required in the present invention was not obtained.
  • the stainless steel pipe of Comparative Example No. 14 had a high average KAM value, and as a result, was unable to obtain the breaking elongation and d 2 ⁇ /d ⁇ 2 required in the present invention.
  • the comparative stainless steel pipe No. 18 had a large standard deviation in the KAM value distribution, and as a result, was unable to obtain the breaking elongation required in the present invention.
  • the stainless steel pipe No. 21 of the comparative example had a large standard deviation in the KAM value distribution, and as a result, the breaking elongation required in the present invention was not obtained.
  • the comparative stainless steel pipe No. 22 had a high average KAM value, and as a result, was unable to obtain the breaking elongation and d 2 ⁇ /d ⁇ 2 required in the present invention.
  • the comparative stainless steel pipe No. 21 of the comparative example had a large standard deviation in the KAM value distribution, and as a result, the breaking elongation required in the present invention was not obtained.
  • the comparative stainless steel pipe No. 22 had a high average KAM value, and as a result, was unable to obtain the breaking elongation and d 2 ⁇ /d ⁇ 2 required in the present invention.
  • the stainless steel pipe No. 24 of the comparative example had a tendency to have a low yield strength as a result of the low total volume fraction of ferrite and martensite.
  • the stainless steel pipe No. 25 of the comparative example had a high volume fraction of the ⁇ phase, and as a result, the d 2 ⁇ /d ⁇ 2 required in the present invention was not obtained.

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Abstract

L'objectif de la présente invention est de fournir un tuyau en acier inoxydable présentant une résistance élevée et une excellente résistance à la fragilisation par l'hydrogène. Par « présentant une excellente résistance à la fragilisation par l'hydrogène », on entend que, lors d'un essai de traction sous chargement en hydrogène, l'allongement à la rupture est supérieur ou égal à 9,0 % et que, lorsqu'un allongement réel est tracé sur l'axe horizontal et une contrainte réelle est tracée sur l'axe vertical dans l'essai de traction, et que l'allongement réel à la charge maximale est désigné par εmax, le taux de variation de la vitesse d'écrouissage dσ/dε par rapport à ε, c'est-à-dire d2σ/dε2, est supérieur ou égal à 200 000 MPa dans la plage où l'allongement réel est compris entre 0,8 εmax et εmax, tous deux inclus. σ désigne la contrainte réelle (MPa), et ε désigne l'allongement réel (pas d'unité). Par « présentant une résistance élevée », on entend que la limite d'élasticité est supérieure ou égale à 450 MPa.　Ce tuyau en acier inoxydable a une structure spécifique, dans laquelle une valeur moyenne de désorientation moyenne de noyau (KAM), qui est une moyenne de valeurs de KAM de la structure en acier, est comprise entre 2,0° et 4,0°, tous deux inclus, et un écart type de la distribution de valeurs de KAM est inférieur ou égal à 1,5°.
PCT/JP2025/001369 2024-03-05 2025-01-17 Tuyau en acier inoxydable et tuyau de puits de pétrole Pending WO2025187217A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004238662A (ja) * 2003-02-04 2004-08-26 Sumitomo Metal Ind Ltd マルテンサイト系ステンレス鋼管及びその製造方法
WO2019065116A1 (fr) * 2017-09-29 2019-04-04 Ｊｆｅスチール株式会社 Tuyau sans soudure en acier inoxydable à base de martensite pour tubage de puits de pétrole, et procédé de fabrication de celui-ci
JP2021167445A (ja) * 2020-04-10 2021-10-21 日本製鉄株式会社 二相ステンレス鋼材
WO2021225103A1 (fr) * 2020-05-07 2021-11-11 日本製鉄株式会社 Tuyau sans soudure en acier inoxydable duplex
WO2024009564A1 (fr) * 2022-07-05 2024-01-11 Ｊｆｅスチール株式会社 Tuyau d'acier inoxydable sans soudure et procede de fabrication de celui-ci

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004238662A (ja) * 2003-02-04 2004-08-26 Sumitomo Metal Ind Ltd マルテンサイト系ステンレス鋼管及びその製造方法
WO2019065116A1 (fr) * 2017-09-29 2019-04-04 Ｊｆｅスチール株式会社 Tuyau sans soudure en acier inoxydable à base de martensite pour tubage de puits de pétrole, et procédé de fabrication de celui-ci
JP2021167445A (ja) * 2020-04-10 2021-10-21 日本製鉄株式会社 二相ステンレス鋼材
WO2021225103A1 (fr) * 2020-05-07 2021-11-11 日本製鉄株式会社 Tuyau sans soudure en acier inoxydable duplex
WO2024009564A1 (fr) * 2022-07-05 2024-01-11 Ｊｆｅスチール株式会社 Tuyau d'acier inoxydable sans soudure et procede de fabrication de celui-ci

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