WO2024071356A1 - Matériau d'acier pour tuyau de canalisation excellent en termes de caractéristiques de résistance à la fragilisation à l'hydrogène ainsi que procédé de fabrication de celui-ci, et tube d'acier pour tuyau de canalisation excellent en termes de caractéristiques de résistance à la fragilisation à l'hydrogène ainsi que procédé de fabrication de celui-ci - Google Patents

Matériau d'acier pour tuyau de canalisation excellent en termes de caractéristiques de résistance à la fragilisation à l'hydrogène ainsi que procédé de fabrication de celui-ci, et tube d'acier pour tuyau de canalisation excellent en termes de caractéristiques de résistance à la fragilisation à l'hydrogène ainsi que procédé de fabrication de celui-ci Download PDF

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Publication number
WO2024071356A1
WO2024071356A1 PCT/JP2023/035558 JP2023035558W WO2024071356A1 WO 2024071356 A1 WO2024071356 A1 WO 2024071356A1 JP 2023035558 W JP2023035558 W JP 2023035558W WO 2024071356 A1 WO2024071356 A1 WO 2024071356A1
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Prior art keywords
steel
temperature
less
hydrogen
content
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PCT/JP2023/035558
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English (en)
Japanese (ja)
Inventor
拓史 岡野
佳宏 西原
奈穂 井上
大地 泉
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Ｊｆｅスチール株式会社
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Publication of WO2024071356A1 publication Critical patent/WO2024071356A1/fr

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    • 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
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • 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
    • 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 a steel material for line pipes that has excellent hydrogen embrittlement resistance and is suitable for applications such as line pipes for transporting hydrogen gas, a manufacturing method thereof, a steel pipe for line pipes, and a manufacturing method thereof.
  • Line pipes for transporting natural gas exist as an existing energy infrastructure. These steel materials have been required to suppress the occurrence of hydrogen-induced cracking in sour environments. Meanwhile, in recent years, hydrogen has been attracting a great deal of attention worldwide as a clean energy source for building a decarbonized society. For this reason, in order to transport large amounts of hydrogen gas, the construction of a hydrogen gas transportation network that uses natural gas mixed with some hydrogen in natural gas line pipes and pressurized hydrogen gas as an alternative is being considered. The transportation pressure during operation of these pipelines is expected to be high pressure of 1 to 40 MPa, and the line pipes will be placed in a high-pressure hydrogen gas exposure environment.
  • Austenitic stainless steels such as SUS316L, which are less susceptible to hydrogen embrittlement than low-alloy steels, have traditionally been used for steel structures used in high-pressure hydrogen gas environments.
  • austenitic stainless steels such as SUS316L are expensive and have low strength, so when designed to withstand high hydrogen pressures, the wall thickness becomes thick, and the price of the hydrogen structure itself becomes expensive. For this reason, there has been a strong demand for low-cost low-alloy steels for hydrogen steel structures that can withstand high-pressure hydrogen gas environments.
  • the steel for high-pressure hydrogen environments described in Patent Document 1 is a steel used in high-pressure hydrogen environments, and by making the Ca/S ratio less than 1.5 or 11 or more, it is said that the diffusible hydrogen concentration ratio is reduced and embrittlement due to diffusible hydrogen is suppressed.
  • Patent Document 2 describes a technology that uses low-alloy high-strength steel adjusted to a specific composition, which has been found to have greater reduction in area and elongation values in a 45 MPa hydrogen atmosphere than JIS G3128SHY685NS in the air tensile strength range of 900 to 950 MPa, and is superior in resistance to embrittlement in a high-pressure hydrogen environment.
  • Patent Document 3 also describes a Cr-Mo high-strength low-alloy steel that is tempered at a relatively high temperature of 560-580°C, with a grain size of 8.4 or more after tempering, and tensile strength adjusted to an extremely narrow range of 900-950 MPa, which results in a low-alloy high-strength steel that exhibits excellent elongation and drawing characteristics even in a 45 MPa hydrogen atmosphere and has excellent resistance to embrittlement in a high-pressure hydrogen environment.
  • the low-alloy steel for high-pressure hydrogen gas environments proposed in Patent Document 4 adds V, increases the Mo content compared to existing steels, raises the tempering temperature, and utilizes V-Mo carbides, improving the carbide morphology at the grain boundaries and significantly improving resistance to embrittlement in hydrogen environments.
  • Patent Document 5 also proposes a steel for high-pressure hydrogen gas storage containers with excellent hydrogen resistance. According to the technology described in Patent Document 5, when manufacturing steel plates, long-term stress relief annealing is performed after normalizing treatment, which causes fine, dense dispersion precipitation of MC-based carbides (Mo, V)C, improving the hydrogen resistance of the steel, including its resistance to hydrogen embrittlement.
  • MC-based carbides Mo, V
  • Patent Document 6 also proposes a steel material in which the metal structure is mainly composed of bainite with an area fraction of 90% or more, and in which cementite with an average grain size of 50 nm or less and an average aspect ratio of 3 or less is dispersed and precipitated in the bainite.
  • Non-Patent Document 1 lists the fatigue strength values of low alloy steels.
  • Non-Patent Document 1 it is known that the fatigue life of materials decreases in a high-pressure hydrogen environment. In other words, if a line pipe material is designed based on a conventional line pipe for natural gas, the service life of the line pipe material will decrease.
  • the above-mentioned conventional technology can suppress the occurrence of hydrogen-induced cracking in a sour environment, it is unable to sufficiently increase the fatigue strength in hydrogen gas. In other words, there is a problem in that it is difficult to simultaneously suppress the occurrence of hydrogen-induced cracking in a sour environment and achieve high fatigue strength in hydrogen gas.
  • the present invention aims to provide a line pipe steel material that has high strength and excellent resistance to hydrogen embrittlement in a high-pressure hydrogen gas environment, suitable for steel structures used in a high-pressure hydrogen gas environment, such as line pipes for 100% hydrogen gas or natural gas containing hydrogen at a partial pressure of 1 MPa or more (natural gas is a gas whose main components are hydrocarbons such as methane and ethane), a manufacturing method thereof, and a line pipe steel pipe and a manufacturing method thereof.
  • ASTM E466, Fatigue Testing at a frequency of 1 Hz, a repetitive waveform of sine wave, a control method of load control, loading conditions of uniaxial tension and compression, and
  • the fatigue limit stress in hydrogen under the above environment is 200 MPa or more
  • the fatigue limit stress in hydrogen of the steel under the above environment/fatigue limit stress in an inert gas environment is 0.90 or more
  • steel materials here includes thin steel plates, thick steel plates, seamless steel pipes, electric resistance welded steel pipes, steel sections, steel bars, etc.
  • the inventors have conducted extensive research into the conditions that must be satisfied by steel materials to obtain steel plates and steel pipes for line pipes that have excellent resistance to hydrogen embrittlement, and have come up with the invention of new high-strength steel plates and steel pipes for line pipes. Furthermore, the steel materials and steel pipes of the present invention have high strength, and in the present invention, high strength refers to a tensile strength of 520 MPa or more.
  • the gist of the present invention is as follows. [1] In mass%, C: 0.02 to 0.15%, Si: 0.01 to 2.0%, Mn: 0.5 to 1.5%, P: 0.0001 to 0.015%, S: 0.0002 to 0.0015%, Al: 0.005 to 0.15%, O: 0.01% or less, N: 0.010% or less, H: 0.0010% or less; Or even more so: Nb: 0 to 0.10%, Ca: 0 to 0.005%, Ti: 0 to 0.1%, Ni: 0 to 2.0%, Cu: 0 to 1.0%, Cr: 0 to 1.0%, Mo: 0 to 0.60%, W: 0 to 1.0%, V: 0 to 0.10%, Zr: 0 to 0.050%, REM: 0 to 0.050%, Mg: 0 to 0.050%, B: 0 to 0.0020%, Hf: 0 to 0.2%, Ta: 0 to 0.2%, Re: 0 to 0.005%, Sn: 0
  • the chemical composition, in mass%, is Nb: 0.001 to 0.10%, Ca: 0.0001 to 0.005%, Ti: 0.005 to 0.1%, Ni: 0.01 to 2.0%, Cu: 0.01 to 1.0%, Cr: 0.01 to 1.0%, Mo: 0.01 to 0.60%, W: 0.01 to 1.0%, V: 0.01 to 0.10%, Zr: 0.0001 to 0.050%, REM: 0.0001 to 0.050%, Mg: 0.0001 to 0.050%, B: 0.0001 to 0.0020%, Hf: 0.0001 to 0.2%, Ta: 0.0001 to 0.2%, Re: 0.0001 to 0.005%, Sn: 0.0001 to 0.3%,
  • the method for producing a steel material for line pipes comprising the steps of: [4] In a steel pipe for line pipe, In mass percent, C: 0.02 to 0.15%, Si: 0.01 to 2.0%, Mn: 0.5 to 1.5%, P: 0.0001 to 0.015%, S: 0.0002 to 0.0015%, Al: 0.005 to 0.15%, O: 0.01% or less, N: 0.010% or less, H: 0.0010% or less; Or even more so: Nb: 0 to 0.10%, Ca: 0 to 0.005%, Ti: 0 to 0.1%, Ni: 0 to 2.0%, Cu: 0 to 1.0%, Cr: 0 to 1.0%, Mo: 0 to 0.60%, W: 0 to
  • the chemical composition, in mass%, is Nb: 0.001 to 0.10%, Ca: 0.0001 to 0.005%, Ti: 0.005 to 0.1%, Ni: 0.01 to 2.0%, Cu: 0.01 to 1.0%, Cr: 0.01 to 1.0%, Mo: 0.01 to 0.60%, W: 0.01 to 1.0%, V: 0.01 to 0.10%, Zr: 0.0001 to 0.050%, REM: 0.0001 to 0.050%, Mg: 0.0001 to 0.050%, B: 0.0001 to 0.0020%, Hf: 0.0001 to 0.2%, Ta: 0.0001 to 0.2%, Re: 0.0001 to 0.005%, Sn: 0.0001 to 0.3%, A steel pipe for line pipe having excellent hydrogen embrittlement resistance according to [4], wherein Sb is 0.0001 to 0.3%.
  • the present invention makes it possible to easily and simply manufacture steel materials with extremely improved resistance to hydrogen embrittlement in a high-pressure hydrogen gas environment, which is of great industrial benefit.
  • the present invention also has the effect of significantly improving the hydrogen embrittlement resistance of steel structures such as line pipes for high-pressure hydrogen gas, improving fatigue resistance, and greatly contributing to extending the life of steel structures.
  • the C content 0.02 to 0.15%
  • the C content is set to 0.02% or more.
  • the C content is 0.03% or more.
  • the weldability decreases. Therefore, the C content is limited to 0.15% or less.
  • the C content is 0.13% or less.
  • the C content is 0.08% or less. More preferably, the C content is 0.05% or less.
  • Si 0.01 to 2.0% Si is added for deoxidation, but if the content is less than 0.01%, the deoxidation effect is insufficient. Therefore, the Si content is 0.01% or more.
  • the Si content is preferably 0.08% or more, and more preferably 0.1% or more.
  • the Si content exceeds 2.0%, the effect is saturated, so the Si content is 2.0% or less.
  • the Si content is preferably 1.8% or less, and more preferably 1.0% or less.
  • the Si content exceeds 0.5%, the toughness and weldability are deteriorated, so the Si content is even more preferably 0.5% or less.
  • Mn 0.5 to 1.5% Mn effectively contributes to improving strength and toughness, but if the content is less than 0.5%, the effect of adding it is poor. Therefore, the Mn content is set to 0.5% or more.
  • the Mn content is preferably 0.6% or more, more preferably 0.7% or more, and even more preferably 0.8% or more.
  • the Mn content is limited to 1.5% or less.
  • the Mn content is preferably 1.4% or less, and even more preferably 1.3% or less.
  • P 0.0001 to 0.015%
  • P is an inevitable impurity element that deteriorates weldability and increases the hardness of the central segregation, thereby deteriorating HIC resistance. This tendency becomes significant when the content exceeds 0.015%, so the upper limit of the P content is set at 0.015%.
  • the P content is preferably 0.010% or less, and more preferably, the P content is 0.008% or less. The lower the content, the better, but from the viewpoint of refining costs, the P content is set to 0.0001% or more.
  • S 0.0002 to 0.0015%
  • S is an inevitable impurity element, and since it becomes MnS inclusions in steel and deteriorates HIC resistance, the less the better, but up to 0.0015% is permissible. For this reason, the S content is set to 0.0015% or less.
  • the S content is preferably 0.0010% or less, and more preferably 0.0008% or less. The lower the content, the better, but from the viewpoint of refining costs, the S content is set to 0.0002% or more.
  • Al 0.005 to 0.15%
  • Al is added as a deoxidizer, but if it is less than 0.005%, it has no effect. Therefore, the Al content is set to 0.005% or more.
  • the Al content is preferably 0.01% or more, and more preferably 0.03% or more.
  • the Al content is limited to 0.15% or less.
  • the Al content is preferably 0.10% or less, more preferably 0.08% or less, and even more preferably 0.05% or less.
  • O 0.01% or less
  • O is a cause of oxide inclusions, so the less the better, but there is no problem if the O content is 0.01% or less. For this reason, the O content is set to 0.01% or less.
  • the O content is preferably 0.005% or less. More preferably, the O content is less than 0.003%. There is no particular lower limit, but since making oxygen 0% increases costs, the O content is preferably 0.001% or more.
  • N 0.010% or less
  • the effect of N on the fatigue properties of steel is small, and if the N content is 0.010% or less, the effect of the present invention is not impaired from the viewpoint of toughness. Therefore, the N content is set to 0.010% or less.
  • the N content is preferably set to 0.008% or less, and more preferably set to 0.006% or less.
  • the N content is further preferably set to 0.004% or less.
  • the N content is preferably set to 0.00001% or more.
  • the N content is preferably set to 0.001% or more.
  • H 0.0010% or less H may be introduced into steel materials in various processes during manufacturing, and if the amount of H introduced is large, the risk of cracking after solidification increases and fatigue crack propagation accelerates. In addition, when the amount of H introduced is large, the fatigue stress limit decreases, so it is important to reduce the amount of hydrogen in the steel material. These effects do not become a problem if the H content is 0.0010% or less, so the H content is set to 0.0010% or less.
  • the H content is preferably 0.0005% or less, more preferably 0.0003% or less, and even more preferably 0.0001% or less. On the other hand, if the H content is less than 0.00001%, it will be a factor of cost increase, so the H content is preferably 0.00001% or more.
  • the amount of hydrogen is the amount of hydrogen remaining after forming of steel materials, steel pipes, UOE, etc.
  • composition of the disclosed steel sheet may contain one or more elements selected from Nb, Ca, Ti, Ni, Cu, Cr, Mo, W, V, Zr, REM, Mg, B, Hf, Ta, Re, Sn, and Sb in the ranges below to further improve the strength and toughness of the steel sheet.
  • Nb 0 to 0.10%
  • Nb is an element effective for increasing the strength and toughness of steel, but if it exceeds 0.10%, the toughness of the weld deteriorates, so if it is contained, the Nb content is 0.10% or less.
  • the Nb content is preferably 0.08% or less. It is more preferable that the Nb content is 0.06% or less.
  • the Nb content may be 0% or more, but if the Nb content is less than 0.001%, it is difficult to obtain the effect of containing Nb, so if it is contained, it is preferably 0.001% or more. It is more preferable that the Nb content is 0.01% or more.
  • Ca 0 to 0.005% Ca is an element effective in improving HIC resistance by controlling the morphology of sulfide-based inclusions, but not only does the effect saturate, but it also deteriorates HIC resistance by reducing the cleanliness of the steel, so if Ca is contained, the amount is limited to 0.005% or less.
  • the Ca content is preferably 0.003% or less.
  • the Ca content is more preferably 0.002% or less.
  • the Ca content may be 0% or more, but if it is less than 0.0001%, the effect of adding it is difficult to obtain, so if it is contained, it is preferably 0.0001% or more.
  • the Ca content is more preferably 0.001% or more.
  • Ti 0 to 0.1%
  • Ti is an element effective for increasing the strength and toughness of steel material, but if it exceeds 0.1%, the toughness of the welded part deteriorates, so if Ti is contained, the Ti content is 0.1% or less.
  • the Ti content is preferably 0.05% or less.
  • the Ti content is more preferably 0.03% or less, and further preferably 0.02% or less.
  • the Ti content may be 0% or more, but if the Ti content is less than 0.005%, the effect of containing Ti is difficult to obtain, so if Ti is contained, it is preferably 0.005% or more.
  • the Ti content is more preferably 0.008% or more.
  • Ni 0 to 2.0%
  • Ni is an element effective in improving toughness and increasing strength, but in order to suppress costs, the Ni content is set to 2.0% or less.
  • the Ni content is preferably 1.5% or less.
  • the Ni content is more preferably 1.2% or less, and even more preferably 1.0% or less.
  • the Ni content may be 0% or more, but in order to obtain the above effects, it is preferable to contain Ni at 0.01% or more.
  • Cu 0 to 1.0%
  • Cu is an element effective in improving toughness and increasing strength, but if the content is too high, weldability deteriorates, so when Cu is contained, it is set to 1.0% or less.
  • the Cu content is preferably 0.5% or less.
  • the Cu content is more preferably 0.3% or less, and further preferably 0.2% or less.
  • the Cu content may be 0% or more, but it is preferable to contain 0.01% or more to obtain the above effect.
  • Cr 0 to 1.0%
  • Cr is an effective element for obtaining sufficient strength even with low C content, but if the content is too high, the hardenability becomes excessive, and the SSCC resistance deteriorates. In addition, weldability also deteriorates.
  • the Cr content is set to 1.0% or less.
  • the Cr content is preferably 0.8% or less.
  • the Cr content is more preferably 0.5% or less, and further preferably 0.1% or less.
  • the Cr amount may be 0% or more, but to obtain this effect, it is preferable to contain Cr at 0.01% or more.
  • the Cr content is more preferably 0.02% or more.
  • Mo 0 to 0.60%
  • Mo is an element effective in improving toughness and increasing strength, and is an element effective in improving SSCC resistance regardless of hydrogen sulfide partial pressure, but if the content is too high, the hardenability becomes excessive, and the SSCC resistance deteriorates. In addition, weldability also deteriorates.
  • the Mo content is 0.60% or less. More preferably, it is 0.50% or less, and further preferably, it is 0.40% or less. Most preferably, the Mo content is 0.03% or less.
  • the Mo content may be 0% or more, but in order to obtain the above effect, it is preferable to contain Mo at 0.005% or more. It is more preferable to contain Mo at 0.01% or more.
  • W 0 to 1.0% W contributes to increasing the strength of steel pipes, but if the W content exceeds 1.0%, the effect saturates and becomes a factor in increasing costs, so if W is contained, the W content is set to 1.0% or less.
  • the W content is preferably set to 0.8% or less. To further reduce costs, the W content is more preferably set to 0.5% or less.
  • the W content is further preferably set to 0.03% or less.
  • the W content may be 0% or more, but in order to obtain the above-mentioned effects, the content is preferably set to 0.01% or more.
  • V 0 to 0.10%
  • V is an element that can be optionally contained to increase the strength and toughness of the steel material, but if the V content exceeds 0.10%, the toughness of the weld deteriorates, so if it is contained, it is set to 0.10% or less.
  • the V content is preferably set to 0.08% or less.
  • the V content is more preferably set to 0.06% or less, and even more preferably set to 0.03% or less.
  • the V content may be 0% or more, but if the content is less than 0.01%, the effect of the content is difficult to obtain, so it is preferably set to 0.01% or more.
  • Zr 0 to 0.050%
  • REM 0 to 0.050%
  • Mg 0 to 0.050%
  • Zr, REM, and Mg are elements that can be optionally contained in order to increase toughness through grain refinement or to increase crack resistance through control of inclusion properties.
  • the content exceeds 0.050%, the effect is saturated, so if any of them is contained, it is set to 0.050% or less. That is, if contained, the Zr content is set to 0.050% or less. It is preferable that the Zr content is set to 0.040% or less. It is more preferable that the Zr content is set to 0.030% or less.
  • the Zr content is set to 0.010% or less, and it is most preferable that the Zr content is set to 0.005% or less.
  • the REM content is set to 0.050% or less. It is preferable that the REM content is set to 0.040% or less. It is more preferable that the REM content is set to 0.030% or less.
  • the Mg content is set to 0.050% or less. It is preferable that the Mg content is set to 0.040% or less. It is more preferable that the Mg content is set to 0.030% or less.
  • the contents of these elements may be 0% or more, but since the effect of the inclusion is difficult to obtain when the contents are less than 0.0001%, it is preferable to set the contents to 0.0001% or more. That is, the Zr content is preferably 0.0001% or more. The Zr content is more preferably 0.0005% or more. The REM content is preferably 0.0001% or more. The REM content is more preferably 0.0005% or more. The Mg content is preferably 0.0001% or more. The Mg content is more preferably 0.0005% or more.
  • B 0 to 0.0020%
  • B is an element that improves hardenability, contributes to increasing the strength of the steel pipe, inhibits the coarsening of prior austenite grains, and improves various properties of the material.
  • the B content is set to 0.0020% or less.
  • the B content is preferably set to 0.0015% or less.
  • the B content is more preferably set to 0.0012% or less. In order to suppress costs, it is even more preferable to set the B content to 0.0010% or less.
  • the B content may be 0% or more, but in order to obtain the above effect, the content is preferably set to 0.0001% or more. More preferably, the B content is 0.0005% or more.
  • Hf 0 to 0.2%
  • Ta 0 to 0.2%
  • the Hf and Ta contents may be 0% or more, but in order to obtain the above-mentioned effect, it is preferable that the contents are 0.0001% or more. That is, the Hf content is preferably 0.0001% or more. More preferably, the Hf content is 0.0010% or more. Also, the Ta content is preferably 0.0001% or more. More preferably, the Ta content is 0.0010% or more.
  • Re 0 to 0.005% Re contributes to increasing the strength of steel materials, but if the content exceeds 0.005%, the effect is saturated and becomes a factor of increasing costs, so if Re is contained, it is set to 0.005% or less.
  • the Re content is preferably set to 0.003% or less.
  • the Re content is more preferably set to 0.002% or less.
  • the Re content may be 0% or more, but in order to obtain the above effect, the content is preferably set to 0.0001% or more. More preferably, it is set to 0.001% or more.
  • Sn 0 to 0.3%
  • Sb 0 to 0.3%
  • the Sb content is set to 0.1% or less. In order to suppress costs, it is even more preferable that the Sb content is set to 0.01% or less.
  • the contents of Sn and Sb may be 0% or more, but in order to obtain the above effects, it is preferable that the contents are 0.0001% or more. That is, it is preferable that the Sn content is set to 0.0001% or more. More preferably, the Sn content is 0.0010% or more.
  • the Sb content is preferably 0.0001% or more, and more preferably 0.0010% or more.
  • the remainder other than the above-mentioned components consists of Fe and unavoidable impurity elements.
  • the metal structure of the steel material of the present invention is described below.
  • the fatigue crack growth rate is reduced by making the retained austenite 3% or less. Reducing the retained ⁇ suppresses the occurrence of fatigue cracks in a hydrogen environment, thereby suppressing the decrease in the fatigue limit stress in hydrogen. For this reason, the retained austenite is set to 3% or less.
  • the retained austenite is preferably 2% or less.
  • the retained austenite is more preferably 1% or less.
  • the retained austenite may be 0%.
  • Bainite has an area fraction of 90% or more at the 1/4 position of the plate thickness
  • the steel structure needs to be a bainite structure.
  • the bainite structure includes bainitic ferrite or granular bainite that transforms during or after controlled cooling, which contributes to transformation strengthening, and also includes tempered bainite. If heterogeneous structures such as ferrite, martensite, pearlite, island martensite, and retained austenite are mixed in the bainite structure, a decrease in strength and a deterioration in toughness will occur, so the smaller the volume fraction of structures other than the bainite phase, the better.
  • the area fraction of bainite is set to 90% or more. It is preferable that the area fraction of bainite is 92% or more. It is more preferable that the area fraction of bainite is 95% or more, and even more preferable that it is 98% or more.
  • the area fraction of bainite may be 100%. Furthermore, since fatigue cracks occur from the inner surface of the steel pipe, the uniformity of the inner surface structure of the steel pipe is important. Therefore, the metal structure is specified at 1/4 of the wall thickness from the inner surface of the steel pipe, and for steel materials, the metal structure is specified at 1/4 of the wall thickness in order to obtain the above effect regardless of which surface is on the inner surface of the steel pipe.
  • the fatigue limit stress in hydrogen of 1 MPa or more is 200 MPa or more, and the fatigue limit stress in hydrogen of 1 MPa or more/inert gas environment is 0.90 or more. If the fatigue limit stress in hydrogen of 1 MPa or more is less than 200 MPa, and the fatigue limit stress in hydrogen of 1 MPa or more/inert gas environment is less than 0.90, it is significantly different from the design conditions of conventional pipelines, and it becomes necessary to increase the steel thickness (steel pipe thickness in the case of steel pipes). For this reason, the fatigue limit stress in hydrogen of 1 MPa or more is 200 MPa or more, and the fatigue limit stress in hydrogen of 1 MPa or more/inert gas environment is 0.90 or more.
  • the fatigue limit stress in hydrogen of 1 MPa or more is 220 MPa or more. It is more preferable that the fatigue limit stress in hydrogen of 1 MPa or more is 250 MPa or more, and even more preferable that it is 270 MPa or more. Although there is no particular upper limit, it is preferable that the fatigue limit stress in hydrogen of 1 MPa or more is 500 MPa or less. In addition, the fatigue limit stress in hydrogen of 1 MPa or more/fatigue limit stress in an inert gas environment is preferably 0.92 or more. The fatigue limit stress in hydrogen of 1 MPa or more/fatigue limit stress in an inert gas environment is more preferably 0.94 or more, and even more preferably 0.96 or more.
  • the inert gas referred to here includes the six elements in Group 0 of the periodic table, helium, neon, argon, krypton, xenon, and radon, as well as air, and an inert gas environment refers to an environment that includes any of the above.
  • the present invention has the above-mentioned chemical components and metal structure, which improves the fatigue limit stress in a high-pressure hydrogen atmosphere and suppresses the decrease in the fatigue limit stress in hydrogen/inert gas, while achieving a tensile strength of 520 MPa or more, making it applicable to hydrogen line pipes.
  • tensile strength There is no particular upper limit for the tensile strength, but it is preferably 950 MPa or less.
  • the thickness of the steel plate is not particularly limited, but is preferably 5 mm or more. It is preferable that the thickness be 30 mm or less.
  • the steel material of the present invention can be produced by sequentially carrying out a heating step, a hot rolling step, a controlled cooling step, and a dehydrogenation step of a steel material (slab).
  • the temperature is the temperature at the center of the thickness of the steel material or the steel pipe.
  • the average cooling rate means the temperature at 1/4 of the thickness from the inner surface of the steel pipe.
  • the temperature at the center of the thickness and the temperature at 1/4 of the thickness from the inner surface of the steel pipe are temperatures estimated from the steel pipe surface temperature measured with a radiation thermometer using heat transfer calculations that take into account the heat transfer coefficient of the steel material.
  • Heating process Heating temperature of steel material 1000-1250°C If the heating temperature of steel material such as billets or slabs is less than 1000°C, the diffusion of micro-segregated impurity elements such as C, P, and S is insufficient, and a homogeneous material cannot be obtained. For this reason, the heating temperature of the steel material is set to 1000°C or higher. On the other hand, if the heating temperature exceeds 1250°C, the crystal grains become too coarse and the toughness deteriorates. Therefore, the heating temperature of the steel material is set to 1250°C or lower. The heating temperature is preferably set to 1200°C or lower. The heating temperature is more preferably set to 1180°C or lower.
  • Hot rolling process Hot rolling end temperature Ar 3 point or more After reheating the steel material, hot rolling is performed to the desired tube thickness or plate thickness, but the end temperature of hot rolling is Ar 3 point or more, which is the ferrite formation temperature. If the temperature is less than Ar 3 point, in the case of a process in which cooling is performed immediately after hot rolling, the strength will decrease due to the formation of a soft ferrite phase.
  • the end temperature of hot rolling is preferably Ar 3 + 30 ° C or more. It is more preferable that the end temperature of hot rolling is Ar 3 + 50 ° C or more. In addition, if the temperature exceeds 1250 ° C, the crystal grains become too coarse and the toughness deteriorates, so the upper limit is preferably 1250 ° C or less. It is more preferable that the end temperature of hot rolling is 1200 ° C or less, and even more preferable that it is 1150 ° C or less.
  • Ar3 point varies depending on the alloying components of the steel, it may be determined by measuring the transformation temperature through experiments for each steel, but it may also be determined from the component composition using the following formula.
  • Ar3 (°C) 910 - 310C (%) - 80Mn (%) - 20Cu (%) - 15Cr (%) - 55Ni (%) - 80Mo (%)
  • the content of each alloying element is expressed as mass %.
  • Cooling start temperature of controlled cooling steel plate surface temperature is Ar 3 point or more If the steel plate surface temperature at the start of cooling is less than Ar 3 point, ferrite is generated before controlled cooling, and strength reduction increases. Therefore, the steel plate surface temperature at the start of cooling is Ar 3 point or more.
  • the steel plate surface temperature at the start of cooling is preferably Ar 3 + 30°C or more. It is more preferable to set it to Ar 3 + 50°C or more. If the cooling start temperature is too high, the crystal grain size becomes too large and the toughness decreases, so the steel plate surface temperature at the start of cooling is preferably less than 1250°C.
  • the steel plate surface temperature at the start of cooling is more preferably 1200°C or less, and even more preferably 1150°C or less.
  • the steel plate surface temperature at the start of cooling is the temperature of the tail end of the steel plate where the cooling start temperature is the lowest.
  • Cooling start time difference between the front end and the tail end of the steel plate in the controlled cooling within 50 seconds If the time difference between the front end and the tail end in the rolling direction of the steel plate at the start of cooling exceeds 50 seconds, the temperature difference between the front end and the tail end at the start of cooling becomes large, so the temperature variation at the time of stopping cooling becomes large, and the variation in Vickers hardness at 0.25 mm below the surface of the steel plate becomes large and the HISC resistance deteriorates. For this reason, the cooling start time difference between the front end and the tail end of the steel plate is within 50 seconds, preferably within 45 seconds. More preferably, it is within 40 seconds.
  • the lower limit is not particularly limited and may be more than 0 seconds.
  • Average cooling rate from 750 ° C to 550 ° C at the center of plate thickness 15 to 50 ° C / s If the average cooling rate from 750°C to 550°C at the center of the plate thickness is less than 15°C/s, the bainite structure is not obtained, and strength is reduced. Therefore, the average cooling rate at the center of the plate thickness is set to 15°C/s or more. From the viewpoint of suppressing the variation in the structure, the average cooling rate at the center of the plate thickness is preferably set to 17°C/s or more. The average cooling rate at the center of the plate thickness is more preferably set to 20°C/s or more, and even more preferably set to 25°C/s or more.
  • the average cooling rate at the center of the plate thickness is set to 50°C/s or less.
  • the average cooling rate at the center of the plate thickness is preferably set to 45°C/s or less.
  • the average cooling rate at the center of the plate thickness is more preferably set to 40°C/s or less.
  • the cooling at the steel plate temperature at the center of the plate thickness of 550°C or less is not particularly limited, but from the viewpoint of suppressing the variation in the structure and grain size, for example, the average cooling rate from 550°C to 300°C is preferably set to 15°C/s or more.
  • the average cooling rate from 550° C. to 300° C. is preferably 50° C./s or less.
  • Cooling stop temperature 250 to 650°C If the cooling stop temperature after hot rolling exceeds 650°C, the bainite transformation becomes incomplete, and the material strength is greatly reduced. For this reason, the cooling stop temperature is set to 650°C or less.
  • the cooling stop temperature is preferably set to 625°C or less.
  • the cooling stop temperature is more preferably set to 600°C or less.
  • the cooling stop temperature is set to 250°C or more. In order to suppress the amount of hydrogen in the steel, the cooling stop temperature needs to be set to a predetermined temperature or more.
  • the cooling stop temperature needs to be set to 250°C or more in order to reduce the amount of hydrogen in the steel.
  • the cooling stop temperature is preferably set to 270°C or more.
  • Dehydrogenation process When hydrogen is present in steel, the acceleration of fatigue crack growth is increased, and the fatigue life and fatigue stress limit in hydrogen are reduced. Therefore, dehydrogenation may be used to release the hydrogen remaining after manufacturing. Dehydrogenation can reduce the amount of hydrogen in the steel by holding the product at high temperature for a certain period of time before use, and it is possible to obtain a steel plate with excellent hydrogen embrittlement resistance in a high-pressure hydrogen gas environment.
  • the holding time R (sec) is preferably determined by the following formula (A) based on the plate thickness and pipe thickness t (mm) of the steel pipe, and the hydrogen diffusion coefficient D (mm ⁇ sec ⁇ 1 ) in steel at room temperature.
  • the hydrogen diffusion coefficient varies depending on the contained components and metal structure, but may be, for example, 1 ⁇ 10 ⁇ 5 to 5 ⁇ 10 ⁇ 3 mm 2 /s, and more preferably 5 ⁇ 10 ⁇ 4 mm 2 /s or less.
  • the dehydrogenation process is carried out before pipe making or welding to connect steel pipes. It is preferable to perform dehydrogenation at a high temperature because the hydrogen diffusion coefficient D at high temperatures becomes small and hydrogen escapes quickly. In the case of high temperatures, the diffusion coefficient D' (diffusion coefficient at each temperature) at which the value of D in the above formula (A) is maintained may be used for calculation. On the other hand, if the temperature T of the dehydrogenation process is too high, the material strength decreases significantly, so the dehydrogenation temperature T is set to 550°C or less. It is preferable that the dehydrogenation temperature T is set to 500°C or less.
  • the dehydrogenation temperature T is set to 400°C or less, and even more preferable that it is set to 300°C or less.
  • the dehydrogenation temperature T is set to room temperature or higher. It is preferable that the dehydrogenation temperature T is set to 50°C or higher. It is more preferable that the dehydrogenation temperature T is set to 100°C or higher, and even more preferable that it is set to 150°C or higher. It is noted that room temperature means 20 ⁇ 10°C.
  • the time and temperature of the dehydrogenation process may include the temperature and time applied when heating in the pipe-making process for electric resistance welded pipes, UOE, etc., as described below.
  • scale on the steel surface inhibits dehydrogenation, it is preferable to remove the scale before carrying out the dehydrogenation process.
  • the removal method There are no limitations on the removal method, but it may be physical cleaning using a high-pressure cleaner, or a chemical method using a scale remover. The effect of scale removal can be obtained if a thickness of about 100 ⁇ m is removed.
  • a UOE steel pipe which is an example of a high-strength steel pipe for line pipe, can be obtained by limiting the manufacturing conditions shown below, and the manufacturing method and conditions will be specifically described.
  • the component composition, metal structure, fatigue limit stress in hydrogen of 1 MPa or more, and fatigue limit stress in hydrogen of 1 MPa or more/fatigue limit stress in an inert gas environment of the UOE steel pipe are the same as those described for the steel material of the first embodiment, and as for the manufacturing method, the heating process, hot rolling process, controlled cooling process after hot rolling, and dehydrogenation process are performed in the same manner as those described for the steel material.
  • the pipe-making process after rolling will be specifically described below.
  • UOE steel pipes are manufactured by bending hot-rolled steel sheets, specifically by groove-cutting the ends of the hot-rolled steel sheets and forming them into a steel pipe shape using a C press, U press, or O press, then seam-welding the butt joints by internal and external welding, and, if necessary, by a pipe expansion process.
  • Any welding method may be used as long as it provides sufficient joint strength and joint toughness, but submerged arc welding is preferred from the viewpoint of excellent welding quality and manufacturing efficiency.
  • Pipe expansion can also be performed on steel pipes that have been formed into a pipe shape by press bending and then have their butt joints seam-welded.
  • an example of the high-strength steel pipe for line pipe according to the present invention is an electric resistance welded steel pipe, which can be obtained by limiting the manufacturing conditions shown below, and the manufacturing method and conditions will be specifically described below.
  • the steel material's component composition, metal structure, fatigue limit stress in hydrogen of 1 MPa or more, and fatigue limit stress in hydrogen of 1 MPa or more/fatigue limit stress in an inert gas environment are the same as those described for the steel material of the first embodiment, and as for the manufacturing method, the steps other than the cooling step after rolling and the pipe making step (heating step, hot rolling step, dehydrogenation treatment step) are carried out in the same manner as those described for the steel material.
  • Cooling process after rolling (controlled cooling process)
  • the cooling start temperature and the average cooling rate of the controlled cooling are the same as those described in the first embodiment.
  • Cooling stop temperature 250 to 650°C If the cooling stop temperature after hot rolling exceeds 650°C, the bainite transformation becomes incomplete, and the material strength is greatly reduced. For this reason, the cooling stop temperature is set to 650°C or less.
  • the cooling stop temperature is preferably set to 620°C or less. It is more preferable that the cooling stop temperature is set to 580°C or less.
  • the cooling stop temperature is set to 250°C or more. In order to suppress the amount of hydrogen in the steel, the cooling stop temperature needs to be set to a predetermined temperature or more.
  • the cooling stop temperature needs to be set to 250°C or more in order to reduce the amount of hydrogen in the steel.
  • the cooling stop temperature is preferably 390°C or more. More preferably, the cooling stop temperature is 450°C or more.
  • the cooling stop temperature is more preferably 480° C. or higher.
  • the material may be allowed to cool naturally, but in order to promote the formation of bainite, it is more preferable to slowly cool the material until the temperature drops by about 50° C. from the cooling stop temperature.
  • the cooling stop temperature here refers to the temperature at the center of the plate thickness.
  • the winding temperature is preferably 650°C or less. Also, the winding temperature is preferably 250°C or more.
  • the electric resistance welded steel pipe given as an example of the present invention is manufactured by forming the steel pipe into a cylindrical shape by cold roll forming, and then butting and welding both circumferential ends of the cylindrical shape together. Furthermore, the electric resistance welded steel pipe may be manufactured by forming the steel pipe into an electric resistance welded steel pipe material (electric resistance welded steel pipe) using a sizing roll that satisfies the following formula (1) (sizing process), and applying an internal pressure p (MPa) that satisfies the following formula (2) to the inner surface of the electric resistance welded steel pipe material (internal pressure application process).
  • the cylindrical shape means that the circumferential cross section of the tube is in a "C" shape.
  • the plate thickness of the hot-rolled steel plate means the plate thickness of the hot-rolled steel plate before the sizing process is performed.
  • X thickness of electric welded steel pipe material (mm) / radius of electric welded steel pipe material (mm)) ⁇ yield strength of electric welded steel pipe material (MPa)
  • MPa yield strength of electric welded steel pipe material
  • the wall thickness of the electric welded steel pipe material given as an example of the steel pipe of the present invention is preferably 5 mm or more, and preferably 30 mm or less.
  • the radius of the electric welded steel pipe material is preferably 400 mm or less.
  • the radius of the electric welded pipe material is preferably 200 mm or more.
  • the yield strength of the electric welded steel pipe material is preferably 480 MPa or more in order to withstand the gas pressure of pipeline operation, and 500 MPa or more is more preferable.
  • the yield strength is preferably 560 MPa or less.
  • the diameter of the sizing roll is set to satisfy the above formula (1) in order to reduce the absolute value of the residual stress in the axial direction of the tube. If the diameter of the sizing roll is less than the right side of the formula (1), the intended residual shear stress of the present invention cannot be obtained.
  • the diameter of the sizing roll is preferably 2000 mm or less.
  • the electric resistance welded steel pipe material is expanded to generate tensile stress in the circumferential direction of the pipe, thereby reducing the absolute value of the residual stress in the circumferential direction of the pipe.
  • the greater the internal pressure p (MPa) in the internal pressure loading step the smaller the absolute value of the residual stress in the circumferential direction of the pipe.
  • the tensile stress generated in the circumferential direction of the pipe becomes higher as the radius of the steel pipe becomes larger and the wall thickness of the steel pipe becomes smaller.
  • the left side (X) of the above equation (2) corresponds to the internal pressure p when the tensile stress generated in the circumferential direction of the pipe is equal to the yield stress of the electric resistance welded steel pipe material.
  • the internal pressure p is set to a value greater than the left side (X) of equation (2) and the electric resistance welded steel pipe material is expanded to the plastic region.
  • the steel material disclosed in the present invention is formed into a tube by press bending, roll forming, UOE forming, etc., and then the butt joint is welded to produce high-strength steel pipe for sour-resistant line pipe (UOE steel pipe, electric resistance welded steel pipe, spiral steel pipe, etc.) with excellent material uniformity within the steel plate, suitable for transporting crude oil and natural gas.
  • UOE steel pipe electric resistance welded steel pipe
  • spiral steel pipe etc.
  • the steel plate disclosed in the present invention for steel pipe it is possible to produce a steel pipe with excellent HISC resistance, even if there is a high hardness region in the weld.
  • billets were produced with the component compositions shown in Tables 1-1, 1-2, and 1-3.
  • the casting speed was 0.05 to 0.2 m/min.
  • the billets were heated to 1000 to 1100°C.
  • hot rolling was performed at 1000°C ⁇ 50°C.
  • the time difference between the head and tail of hot rolling was 30 to 45 seconds, and the steel plate was manufactured with a target thickness of 20 mmt. Controlled cooling was started when the surface temperature reached Ar 3 + 50°C.
  • steel materials were manufactured under the conditions shown in Tables 2-1, 2-2, and 2-3. For some steel materials (steel materials Nos.
  • the hot-rolled steel sheet was bent and the two ends were butted together and welded to form a pipe.
  • the hot-rolled steel sheet was formed into a cylindrical shape by cold roll forming, and the two circumferential ends of the cylindrical shape were butted together and welded to form a pipe.
  • Steel pipes Nos. 1 to 14, 16 to 30, and 92, and Nos. 15, 31 to 55, and 93 to 98 were obtained.
  • the dehydrogenation treatment was performed in the range of room temperature to 550°C.
  • the dehydrogenation treatment temperature Y shown in Table 2 was performed in the range of room temperature to 550°C, and N was performed at a dehydrogenation treatment temperature of over 550°C. After it was confirmed that the center temperature Tc reached room temperature, which was the target temperature, the temperature was maintained for R (sec) so as to satisfy the above formula (A).
  • billets having the composition shown in Steel No. 15 in Table 1-1 and Steel No. 56 in Table 1-2 were produced at various casting speeds shown in Table 3, and the billets were heated to 1000 to 1100°C. Then, hot rolling was performed at 1000 ⁇ 50°C. The time difference between the head and tail of hot rolling was 30 to 45 seconds, and the steel plate was produced with a target thickness of 20 mmt. The cooling start temperature was controlled cooling when the surface temperature reached Ar 3 +50°C. Then, steel materials and steel pipes were produced under the conditions shown in Table 3. Steel Nos. 15-1 to 3 and 56-1 to 3 were as-is steel materials, and steel pipes Nos.
  • 15-11, 15-12, 56-11, and 56-12 were produced by a pipe-making process in which hot-rolled steel plates were bent and both ends were butt-welded, and steel pipes Nos. Nos. 15-13 and 56-13 were obtained by a controlled cooling process, followed by a pipe-making process in which the hot-rolled steel sheet was formed into a cylindrical shape by cold rolling, and both circumferential ends of the cylindrical shape were butted together and electric resistance welded.
  • the metal structure and mechanical properties were evaluated using the following methods: The tempering temperature was adjusted so that the tensile strength of the material was in the range of 520 MPa to 700 MPa.
  • the metal structure and properties of the obtained steel material and steel pipe were evaluated, and the results are shown in Tables 2-1, 2-2, 2-3, and 3.
  • the evaluation methods were as follows.
  • Temperature-programmed hydrogen analysis The amount of hydrogen remaining in the steel was measured using a temperature-programmed desorption analysis method, using a low-temperature temperature-programmed hydrogen analyzer (gas chromatograph type) (JTF-20AL). Temperature-programmed desorption analysis was performed in the temperature range from room temperature to 400°C at a heating rate of 200°C/h, and the sum of the results was taken as the amount of hydrogen.
  • the test specimens were cylindrical, 30 mm long in the longitudinal direction of the steel pipe, at a 1/4 position of the plate thickness of the steel plate and a 1/4 position from the inner surface of the steel pipe, and had a diameter of 7 ⁇ . This amount of hydrogen was measured before the steel was subjected to the high-pressure hydrogen fatigue test described in the aging section below, and is the amount of H shown in Tables 1-1, 1-2, and 1-3.
  • the stress at which the specimen did not break after 2 million repetitions was defined as the fatigue limit stress in hydrogen. It was determined that the specimen passed the test if the fatigue limit stress in hydrogen obtained in this test was 200 MPa or more and the ratio of the fatigue limit strength in hydrogen to the fatigue limit stress in inert gas environment was 0.90 or more.
  • All of the examples of the present invention had excellent hydrogen embrittlement resistance, with a fatigue limit stress in hydrogen of 200 MPa or more, and a ratio of the fatigue limit strength in an inert gas atmosphere to the fatigue limit stress in hydrogen/fatigue limit stress in an inert gas environment of 0.90 or more. Furthermore, the tensile strength was 520 MPa or more.
  • steel pipes were manufactured under the following manufacturing conditions, and their characteristics were evaluated. Using steel types No. 1, 15, and 56 shown in Tables 1-1 and 1-2, they were manufactured under the same conditions as steel materials No. 1, 15, 56, 15-12, and 56-12 shown in Tables 2-1, 2-2, and 3 up until the controlled cooling process, and characteristics were evaluated when the dehydrogenation treatment conditions were changed. Steel pipe forming was performed in the same manner as in Example 1. The results are shown in Table 4.
  • the dehydrogenation temperature T (atmosphere temperature) of steel pipe and steel material No. 1A, 15A, 56A, 15-12A, and 56-12A was set to 50°C, and the holding time tc after the plate thickness center temperature Tc reached 50°C was set to satisfy the formula (A).
  • the dehydrogenation temperature T (atmosphere temperature) of steel pipe and steel material No. 1B, 15B, 56B, 15-12B, and 56-12B was set to 50°C, and the holding time tc after the plate thickness center temperature Tc reached 50°C was set to satisfy the formula (A) described above, but the holding time tc after the plate thickness center temperature Tc reached 50°C did not satisfy the formula (A) described above.
  • the dehydrogenation temperature T (atmosphere temperature) is 50° C., but neither the atmospheric temperature holding time t nor the holding time tc after the plate thickness center temperature Tc reaches 50° C. satisfies the above-mentioned formula (A).
  • dehydrogenation holding time t is Y
  • dehydrogenation treatment temperature T ambient temperature
  • holding time t satisfies formula (A)
  • dehydrogenation holding time t is N
  • dehydrogenation treatment temperature T ambient temperature
  • holding time tc at steel center temperature Tc is Y means that the holding time tc after the plate thickness center temperature Tc reaches 50°C satisfies formula (A), while “holding time tc at steel center temperature Tc is N” means that the plate thickness center temperature Tc reaches 50°C, but the holding time tc after Tc reaches 50°C does not satisfy formula (A).
  • All of the inventive examples of the present invention had a fatigue limit stress in hydrogen of 200 MPa or more, and the ratio of the fatigue limit strength in an inert gas atmosphere to the fatigue limit stress in hydrogen/fatigue limit stress in an inert gas environment was 0.90 or more. Furthermore, the tensile strength was 520 MPa or more. Among these, the fatigue properties were superior when the dehydrogenation treatment was performed under more favorable conditions.

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Abstract

L'invention a pour objet de fournir un matériau d'acier pour tuyau de canalisation ainsi qu'un procédé de fabrication de celui-ci, et un tube d'acier pour tuyau de canalisation ainsi qu'un procédé de fabrication de celui-ci. Le matériau d'acier pour tuyau de canalisation de l'invention est adapté à une structure d'acier mise en œuvre sous un environnement d'hydrogène gazeux haute pression tel qu'un tuyau de canalisation pour un gaz 100% hydrogène ou un gaz naturel (le gaz naturel consistant en un gaz principalement composé d'un hydrocarbure tel qu'un méthane, un éthane, ou similaire) contenant un hydrogène de pression partielle supérieure ou égale à １ＭＰａ, et se révèle hautement résistant et excellent en termes de caractéristiques de résistance à la fragilisation à l'hydrogène sous un environnement d'hydrogène gazeux haute pression.　Plus précisément, l'invention concerne un matériau d'acier pour tuyau de canalisation excellent en termes de caractéristiques de résistance à la fragilisation à l'hydrogène qui présente une composition chimique et une structure spécifiques, présente une contrainte de limite de fatigue dans l'hydrogène à 1MPa ou plus supérieure ou égale à ２００ＭＰａ, et présente un rapport contrainte de limite de fatigue dans l'hydrogène à 1MPa ou plus / contrainte de limite de fatigue sous un environnement de gaz inerte, supérieur ou égal à ０,９０.
PCT/JP2023/035558 2022-09-29 2023-09-28 Matériau d'acier pour tuyau de canalisation excellent en termes de caractéristiques de résistance à la fragilisation à l'hydrogène ainsi que procédé de fabrication de celui-ci, et tube d'acier pour tuyau de canalisation excellent en termes de caractéristiques de résistance à la fragilisation à l'hydrogène ainsi que procédé de fabrication de celui-ci WO2024071356A1 (fr)

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JP2012122103A (ja) * 2010-12-09 2012-06-28 Sumitomo Metal Ind Ltd 耐水素誘起割れ性、脆性亀裂伝播停止特性および耐食性に優れた厚鋼板
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WO2020137812A1 (fr) * 2018-12-26 2020-07-02 Ｊｆｅスチール株式会社 Acier pour environnements à hydrogène gazeux à haute pression, structure en acier pour environnements à hydrogène gazeux à haute pression et procédé de production d'acier pour environnements à hydrogène gazeux à haute pression
WO2022030818A1 (fr) * 2020-08-07 2022-02-10 주식회사 포스코 Plaque d'acier présentant une excellente résistance à la fragilisation par l'hydrogène et une excellente ténacité et son procédé de fabrication
JP2022068942A (ja) * 2020-10-23 2022-05-11 Ｊｆｅスチール株式会社 高圧水素ガス環境用鋼材およびその製造方法
WO2022209896A1 (fr) * 2021-03-30 2022-10-06 Ｊｆｅスチール株式会社 Tuyau en acier pour de l'hydrogène haute pression, récipient pour de l'hydrogène haute pression, et procédé permettant de fabriquer ledit tuyau en acier

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