WO2020003499A1 - Tuyau d'acier et tôle d'acier - Google Patents

Tuyau d'acier et tôle d'acier Download PDF

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Publication number
WO2020003499A1
WO2020003499A1 PCT/JP2018/024839 JP2018024839W WO2020003499A1 WO 2020003499 A1 WO2020003499 A1 WO 2020003499A1 JP 2018024839 W JP2018024839 W JP 2018024839W WO 2020003499 A1 WO2020003499 A1 WO 2020003499A1
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steel
steel sheet
metal structure
steel pipe
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PCT/JP2018/024839
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English (en)
Japanese (ja)
Inventor
篠原　康浩
原　卓也
潔 海老原
一輝 筒井
服部　豊
望 阿部
晃 橋本
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Nippon Steel Corp
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Nippon Steel Corp
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Priority to KR1020217001704A priority Critical patent/KR102457409B1/ko
Priority to CN201880094993.XA priority patent/CN112313357B/zh
Priority to PCT/JP2018/024839 priority patent/WO2020003499A1/fr
Priority to JP2018556509A priority patent/JP6460297B1/ja
Priority to EP18923989.0A priority patent/EP3816311B1/fr
Publication of WO2020003499A1 publication Critical patent/WO2020003499A1/fr
Anticipated expiration legal-status Critical
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    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/02—Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation
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    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
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    • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
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    • C21D8/0221—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
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    • C21D8/0247—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
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    • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
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    • C21D1/78—Combined heat-treatments not provided for above
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    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite
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    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
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    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
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Definitions

  • the present invention relates to a steel pipe and a steel sheet suitable as a material of the steel pipe.
  • Patent Documents 1 and 2 Steel pipes having excellent HIC resistance have hitherto been disclosed, for example, in Patent Documents 1 and 2, by purifying steel, reducing inclusions, controlling the form of sulfide-based inclusions by adding Ca, It has been manufactured using technologies such as reducing the center segregation by light pressure during casting and accelerated cooling.
  • Patent Document 3 discloses a method for producing a thin sour-resistant steel plate having a thickness of 15 mm or less.
  • the production method of Patent Document 3 defines the conditions of finish rolling from the viewpoint of improving low-temperature toughness.
  • Patent Documents 1 to 4 there is a problem that the steel sheet is subjected to accelerated cooling and the surface layer of the steel sheet is hardened. As a result of the investigation by the present inventors, it was found that SSC resistance may be reduced in such a steel sheet having a hardened surface layer.
  • the sheet when the sheet thickness is small, as described in Non-Patent Document 1, the sheet may be manufactured by air cooling after rolling without applying accelerated cooling. However, when manufactured by air cooling, ferrite (polygonal ferrite) is generated, and the SSC resistance may be reduced.
  • ferrite polygonal ferrite
  • the present invention does not use expensive, easily segregated elements such as V, Cu, Ni, and / or Mo as essential elements for securing strength,
  • a steel pipe having a strength of X60 grade, excellent DWTT characteristics at ⁇ 30 ° C., and excellent SSC resistance and HIC resistance, and having a base material steel plate thickness (wall thickness of steel pipe) of 15 mm or less. And a steel plate as a material of the steel pipe.
  • a hot-rolled steel sheet obtained by hot rolling a steel slab having a predetermined chemical composition at a finish rolling temperature of 830 to 1000 ° C. is accelerated and cooled in two stages, and then restored to a required temperature. It has been found that by heating, a steel pipe having a strength of X60 to X70 according to the API standard, excellent DWTT characteristics, SSC resistance and HIC resistance and a wall thickness of 15 mm or less can be manufactured.
  • the steel pipe according to the present embodiment has a predetermined strength by controlling the rolling and cooling conditions in the thick plate process after suppressing the Ceq low in a steel plate having a thickness of 15 mm or less used as a material of the base material portion. DWTT characteristics, SSC resistance and HIC resistance are obtained. This idea is greatly different from the technology of manufacturing a steel pipe by Asroll (as-rolled) or normalizing (normalizing) by adding a large amount of alloying elements.
  • the present invention has been made based on the above findings, and the gist is as follows.
  • a steel pipe includes a base material portion formed of a cylindrical steel plate, and a welded portion provided at a butt portion of the steel plate and extending in a longitudinal direction of the steel plate.
  • the steel sheet has a chemical composition of 0.030 to 0.070% by mass, Si: 0.05 to 0.50%, Mn: 1.05 to 1.65%, and Al: 0.010% by mass.
  • Ti 0.005 to 0.020%, Nb: 0.005 to 0.045%, Ca: 0.0010 to 0.0050%, N: 0.0010 to 0.0050%, Ni: 0 to 0.50%, Mo: 0 to 0.50%, Cr: 0 to 0.50%, Cu: 0 to 0.50%, V: 0 to 0.100%, Mg: 0 to 0 0.0100%, REM: 0 to 0.0100%, P: 0.015% or less, S: 0.0015% or less, O: 0.0040% or less
  • the balance is composed of Fe and impurities, and the steel sheet has a Ceq defined by the following formula (I) of 0.250 to 0.350, and the steel sheet has a Ceq of 1.50 in the depth direction from the surface of the base material portion.
  • the internal metal structure which is a metal structure in the range from more than 0 mm to the center of the plate thickness, contains 85% or more of granular bainite and / or bainite in total area ratio, and contains 1.0% or less of MA in area ratio.
  • the maximum hardness is 248 Hv or less and the average hardness is 170 to 220 Hv
  • the base material portion is parallel to the plate surface at a position of 1/4 of the plate thickness in the plate thickness direction from the surface.
  • Metal structure is granular Wherein one or both of bainite and tempered bainite in a total area of 95% or more, the maximum hardness of the surface layer portion metallographic structure is not more than 250 Hv, a plate thickness of the steel sheet is 15mm or less.
  • Ceq [C] + [Mn] / 6 + ([Ni] + [Cu]) / 15 + ([Cr] + [Mo] + [V]) / 15 (I)
  • [C], [Mn], [Ni], [Cu], [Cr], [Mo] and [V] in the formula (I) represent C, Mn, Ni, Cu, Cr and Mo in the steel sheet. , V in mass%.
  • the chemical composition is Ni: 0.05 to 0.50%, Mo: 0.05 to 0.50%, Cr: 0.05 to 0 in mass%. .50%, Cu: 0.05 to 0.50%, V: 0.010 to 0.100%, Mg: 0.0001 to 0.0100%, REM: 0.0001 to 0.0100% It may include one or more selected from the group.
  • the remainder of the internal metal structure may be made of ferrite.
  • a steel sheet according to another aspect of the present invention is used for the base material portion of the steel pipe according to any one of the above (1) to (3).
  • an additional element such as V, Cu, Ni, and / or Mo
  • it has a strength of X60 to X70 (tensile strength of 520 MPa to 760 MPa) according to API standards, and has a DWTT characteristic.
  • a high-strength steel sheet for line pipes excellent in DWTT characteristics, sulfide stress cracking resistance, and hydrogen-induced cracking resistance which is suitable as a line pipe for transporting oil, natural gas, and the like, and this steel sheet as a base metal
  • a steel pipe for a line pipe excellent in DWTT characteristics, sulfide stress cracking resistance and hydrogen-induced cracking resistance which is suitable as a line pipe for transporting oil, natural gas, and the like, and this steel sheet as a base metal
  • a steel pipe for a line pipe excellent in DWTT characteristics, sulfide stress cracking resistance and hydrogen-induced cracking resistance which is suitable as a line pipe for transporting oil, natural gas, and the like
  • tissue photograph observed by the scanning electron microscope which shows the internal metallographic structure which is a metal structure in the range from more than 1.0 mm in the depth direction to the center of the thickness from the surface of the base material portion of the steel pipe according to the present embodiment.
  • tissue photograph observed with the scanning electron microscope which shows the surface layer part metal structure which is a metal structure in the range from the surface of the base material part of the steel pipe which concerns on this embodiment to depth direction 1.0mm.
  • a steel pipe according to an embodiment of the present invention (hereinafter referred to as a steel pipe according to the present embodiment) is provided in a base material portion formed of a tubular steel plate and a butt portion of the steel plate, and is a weld extending in a longitudinal direction of the steel plate.
  • the steel sheet has a chemical composition of C: 0.030 to 0.070%, Si: 0.05 to 0.50%, Mn: 1.05 to 1.65 by mass%. %, Al: 0.010 to 0.070%, Ti: 0.005 to 0.020%, Nb: 0.005 to 0.045%, Ca: 0.0010 to 0.0050%, N: 0.
  • Ni 0.50% or less
  • Mo 0.50% or less
  • Cr 0.50% or less
  • Cu 0.50% or less
  • V 1 selected from the group consisting of 0.100% or less, Mg: 0.0100% or less, and REM: 0.0100% or less Or two or more kinds, P: 0.015% or less, S: 0.0015% or less, O: 0.0040% or less, and the balance: Fe and impurities.
  • Ceq defined in 1) is 0.250 to 0.350
  • An internal metal structure that is a metal structure in a range from more than 1.0 mm to a plate thickness center in a depth direction from the surface of the base material portion includes one or both of granular bainite and bainite in a total area ratio of 85% or more,
  • MA may contain 1.0% or less in area ratio and may contain ferrite as the balance
  • the maximum hardness is 248 Hv or less
  • the average hardness is 170 to 220 Hv
  • the base material portion has a texture in which the degree of integration of ⁇ 100 ⁇ ⁇ 110> is 1.5 or more in a plane parallel to the plate surface at a position 1 / of the plate thickness in the plate thickness direction from the surface.
  • a surface layer metal structure that is a metal structure in a range from the surface of the base material portion to 1.0 mm in the depth direction includes one or both of granular bainite and tempered bainite in a total area ratio of 95% or more,
  • the maximum hardness of the surface layer metal structure is 250 Hv or less,
  • the plate thickness of the steel plate is 15 mm or less.
  • the steel sheet according to the present embodiment is used for the base material of the steel pipe according to the present embodiment.
  • C 0.030-0.070%
  • C is an element that improves the strength of steel. If the C content is less than 0.030%, the effect of improving strength cannot be sufficiently obtained. Therefore, the C content is set to 0.030% or more. Preferably it is 0.040% or more. On the other hand, when the C content exceeds 0.070%, the strength is excessively increased, and the HIC resistance is reduced. Therefore, the C content is set to 0.070% or less.
  • the C content is preferably 0.060% or less from the viewpoint of suppressing a decrease in weldability and toughness.
  • Si 0.05 to 0.50% Si is an element that functions as a deoxidizer during steelmaking. If the Si content is less than 0.05%, this effect cannot be sufficiently obtained. Therefore, the Si content is set to 0.05% or more. On the other hand, if the Si content exceeds 0.50%, the toughness of the heat affected zone (HAZ) decreases. Therefore, the Si content is set to 0.50% or less. Preferably it is 0.35% or less.
  • Mn 1.05 to 1.65%
  • Mn is an element that contributes to improving the strength and toughness of steel. If the Mn content is less than 1.05%, the effect of improving strength and toughness cannot be sufficiently obtained. Therefore, the Mn content is set to 1.05% or more. It is preferably at least 1.15%.
  • Mn is also an element that forms MnS and reduces the HIC resistance. If the Mn content exceeds 1.65%, the HIC resistance decreases, so the Mn content is set to 1.65% or less. Preferably it is 1.50% or less.
  • Al 0.010 to 0.070%
  • Al is an element that functions as a deoxidizing agent. If the Al content is less than 0.010%, this effect cannot be sufficiently obtained. Therefore, the Al content is set to 0.010% or more. Preferably it is 0.020% or more. On the other hand, if the Al content exceeds 0.070%, Al oxides accumulate to form clusters, and the HIC resistance decreases. Therefore, the Al content is set to 0.070% or less. Preferably it is 0.040% or less, more preferably 0.030% or less.
  • Ti 0.005 to 0.020%
  • Ti is an element that forms a nitride and contributes to refinement of crystal grains. If the Ti content is less than 0.005%, the above effects cannot be sufficiently obtained. Therefore, the Ti content is set to 0.005% or more. Preferably it is 0.008% or more. On the other hand, if the Ti content exceeds 0.020%, coarse nitrides are generated, and the HIC resistance decreases. Therefore, the Ti content is set to 0.020% or less. Preferably it is 0.015% or less.
  • Nb 0.005 to 0.045%
  • Nb is an element that expands the non-recrystallization temperature range to make crystal grains fine and forms carbides and nitrides, thereby contributing to improvement in the strength of steel. If the Nb content is less than 0.005%, the above effects cannot be sufficiently obtained. Therefore, the Nb content is set to 0.005% or more. Preferably it is 0.010% or more. On the other hand, when the Nb content exceeds 0.045%, coarse carbides and nitrides are generated, and the HIC resistance decreases. In addition, elongation and toughness are also reduced. Therefore, the Nb content is set to 0.045% or less. Preferably it is 0.035% or less.
  • Ca 0.0010 to 0.0050%
  • Ca is an element that generates CaS and suppresses the generation of MnS extending in the rolling direction, thereby contributing to an improvement in HIC resistance. If the Ca content is less than 0.0010%, the above effects cannot be sufficiently obtained. Therefore, the Ca content is set to 0.0010% or more. Preferably it is 0.0020% or more. On the other hand, when the Ca content exceeds 0.0050%, Ca oxide accumulates, and the HIC resistance decreases. Therefore, the Ca content is set to 0.0050% or less. Preferably it is 0.0040% or less.
  • N 0.0010 to 0.0050%
  • N is an element that contributes to the refinement of the structure by forming a nitride that suppresses coarsening of austenite grains during heating. If the N content is less than 0.0010%, the effect of refining the structure cannot be sufficiently obtained. Therefore, the N content is set to 0.0010% or more. Preferably it is 0.0020% or more. On the other hand, when the N content exceeds 0.0050%, coarse nitrides are generated, and the HIC resistance is reduced. Therefore, the N content is set to 0.0050% or less. Preferably it is 0.0040% or less.
  • Ni, Mo, Cr if necessary, in order to improve strength, toughness, and other properties.
  • Cu, V, Mg, and REM may be contained in the following range. However, each of these elements is an arbitrary element that is not an essential element, and thus the lower limit is 0%.
  • Ni is an element that contributes to improving the toughness, strength, and corrosion resistance of steel. If the Ni content is less than 0.05%, the above effects cannot be sufficiently obtained. Therefore, to obtain these effects, the Ni content is preferably set to 0.05% or more. More preferably, it is 0.10% or more. On the other hand, when the Ni content exceeds 0.50%, the hardness of the base material portion exceeds 248 Hv, and the HIC resistance deteriorates. Therefore, even when Ni is contained, the Ni content is set to 0.50% or less. Preferably it is 0.35% or less.
  • Mo 0 to 0.50%
  • Mo is an element that contributes to improving the hardenability of steel. If the Mo content is less than 0.05%, the above effects cannot be sufficiently obtained. Therefore, when obtaining the above effects, the Mo content is preferably set to 0.05% or more. More preferably, it is 0.10% or more. On the other hand, when the Mo content exceeds 0.50%, the hardness of the base material portion exceeds 248 Hv, and the HIC resistance deteriorates. Therefore, even when Mo is contained, the Mo content is set to 0.50% or less. Preferably it is 0.35% or less.
  • Cr 0 to 0.50% Cr is an element that contributes to improving the strength of steel. If the Cr content is less than 0.05%, the above effects cannot be sufficiently obtained. Therefore, when obtaining the above effects, the Cr content is preferably set to 0.05% or more. More preferably, it is 0.10% or more. On the other hand, if the Cr content exceeds 0.50%, the strength is excessively increased, and the toughness is reduced. Therefore, even when it is contained, the Cr content is set to 0.50% or less. Preferably it is 0.35% or less.
  • Cu 0 to 0.50%
  • Cu is an element that contributes to increasing the strength of steel and improving corrosion resistance. If the Cu content is less than 0.05%, the above effects cannot be sufficiently obtained. Therefore, when the above effects are obtained, the Cu content is preferably set to 0.05% or more. More preferably, it is 0.10% or more. On the other hand, when the Cu content exceeds 0.50%, the maximum hardness of the base material portion exceeds 248 Hv, and the HIC resistance deteriorates. Therefore, the Cu content is set to 0.50% or less even when it is contained. Preferably it is 0.35% or less.
  • V 0 to 0.100%
  • V is an element that forms carbides and nitrides and contributes to improving the strength of steel. If the V content is less than 0.010%, the above effects cannot be sufficiently obtained. Therefore, when obtaining the above effects, the V content is preferably set to 0.010% or more. It is more preferably at least 0.030%. On the other hand, if the V content exceeds 0.100%, the toughness of the steel decreases. Therefore, the V content is set to 0.100% or less. Preferably it is 0.080% or less.
  • Mg 0 to 0.0100%
  • Mg is an element that forms a fine oxide that contributes to improvement in toughness by suppressing coarsening of crystal grains. If the Mg content is less than 0.0001%, the above effects cannot be sufficiently obtained. Therefore, when obtaining the above effects, the Mg content is preferably set to 0.0001% or more. More preferably, it is 0.0010% or more. On the other hand, when the Mg content exceeds 0.0100%, the oxides are agglomerated and coarsened, and the HIC resistance and toughness are reduced. Therefore, even if it is contained, the Mg content is set to 0.0100% or less. Preferably it is 0.0050% or less.
  • REM 0-0.0100% REM is an element that controls the form of sulfide-based inclusions and contributes to improvement in toughness. If the REM content is less than 0.0001%, the above effects cannot be sufficiently obtained. Therefore, in order to obtain the above effects, the REM content is preferably set to 0.0001% or more. More preferably, it is 0.0010% or more. On the other hand, if the REM content exceeds 0.0100%, oxides are generated, and the cleanliness of the steel is reduced, and as a result, the toughness is reduced. Therefore, even when it is contained, the REM content is set to 0.0100% or less. Preferably it is 0.0060% or less. In this embodiment, REM means a rare earth element and is a general term for 17 elements of Sc, Y and lanthanoid, and the REM content indicates the total content of these 17 elements.
  • the base material portion (steel plate according to the present embodiment) of the steel pipe according to the present embodiment basically includes the above essential elements, optionally includes the above optional elements, and the balance is composed of Fe and impurities.
  • impurities are components that are mixed from raw materials such as ore or scrap or the like from various environments in the manufacturing process when steel products are manufactured industrially, and do not adversely affect the properties of the steel. Means acceptable.
  • P, S, O, Sb, Sn, Co, As, Pb, Bi, and H are preferably controlled in a range described later.
  • P 0.015% or less
  • P is an impurity element. If the P content exceeds 0.015%, the HIC resistance is significantly reduced. Therefore, the P content is set to 0.015% or less. Preferably it is 0.010% or less. Since the smaller the content, the better, the lower limit includes 0%. However, reducing the P content to less than 0.003% significantly increases manufacturing costs. Therefore, 0.003% is a substantial lower limit of the P content.
  • S 0.0015% or less
  • S is an element that generates MnS that elongates in the rolling direction during hot rolling and reduces the HIC resistance. If the S content exceeds 0.0015%, the HIC resistance is significantly reduced. Therefore, the S content is set to 0.0015% or less. Preferably it is 0.0010% or less. The lower the S content, the better, so the lower limit contains 0%. However, reducing the S content to less than 0.0001% significantly increases manufacturing costs. Therefore, 0.0001% is a substantial lower limit of the S content.
  • O 0.0040% or less
  • O is an element inevitably remaining in steel after deoxidation. If the O content exceeds 0.0040%, an oxide is generated, and the HIC resistance is reduced. Therefore, the O content is set to 0.0040% or less. Preferably it is 0.0030% or less. The lower the O content, the better, so the lower limit contains 0%. However, when the O content is reduced to less than 0.0010%, the production cost is significantly increased. Therefore, 0.0010% is a practical lower limit of the O content in practical steel sheets.
  • Ceq 0.250-0.350 Ceq (carbon equivalent) is an index indicating the hardenability of a steel sheet.
  • Ceq defined by the following equation (1) is set to 0.250 to 0.350.
  • Ceq [C] + [Mn] / 6 + ([Ni] + [Cu]) / 15 + ([Cr] + [Mo] + [V]) / 5 (1)
  • [C], [Mn], [Ni], [Cu], [Cr], [Mo], and [V] in the formula (1) are C, Mn, Ni, Cu, This is the content of Cr, Mo, and V in mass%.
  • Ceq is set to 0.250 or more. Preferably it is 0.260 or more.
  • Ceq exceeds 0.350, the hardenability becomes too high, and the maximum hardness in the internal metal structure exceeds 248 Hv and / or the maximum hardness in the surface layer metal structure exceeds 250 Hv. As a result, the HIC resistance and / or SSC resistance decreases. Therefore, Ceq is set to 0.350 or less. Preferably it is 0.340 or less, more preferably 0.330 or less.
  • Metal structure ranging from more than 1.0 mm to the center of the thickness in the depth direction (thickness direction) from the surface of the steel sheet of the base material portion: one of granular bainite and bainite having a total area ratio of 85% or more. Or both, and the area ratio of MA is 1.0% or less.
  • the metal structure in the range from more than 1.0 mm to the center of the sheet thickness in the depth direction from the steel sheet surface. (Hereinafter, it may be simply referred to as “internal metal structure.”) Is a metal structure containing one or both of granular bainite and bainite in a total area ratio of 85% or more.
  • the total area ratio of granular bainite and / or bainite is less than 85%, it becomes difficult to secure required mechanical properties and HIC resistance. Therefore, the total area ratio of one or both of granular bainite and bainite is 85% or more. Preferably it is 90% or more. Since the area ratio depends on the type of steel and the cooling rate, the upper limit may be 100%, but 95% is a substantial upper limit.
  • the area ratio of MA (Martensite-Austenite Constituent) exceeds 1.0%, the DWTT characteristics deteriorate. Therefore, in the internal metal structure, the area ratio of MA is set to 1.0% or less. MA may be 0%.
  • the remainder of the internal metal structure may be made of ferrite.
  • Metal structure up to 1.0 mm in the depth direction from the surface of the steel sheet: One or both of granular bainite and tempered bainite in an area ratio of 95% or more. It is preferable that the surface layer metal structure contains granular bainite and tempered bainite in a total area ratio of 95% or more, because the SSC resistance is improved.
  • the measurement of the area ratio in the metal structure can be obtained by observing the metal structure with a scanning electron microscope at, for example, 1000 times magnification. Since the structure at a position (t / 4) of the plate thickness from the surface of the steel plate indicates a representative structure of the internal metallographic structure, in this embodiment, the t / 4 of the base material (steel plate) of the steel pipe is used. Is observed, and if the structure at t / 4 is the above-described structure, it is determined that the internal metallographic structure is within the above-described range.
  • the structure of the surface layer portion is obtained by measuring positions of 0.1 mm, 0.2 mm, and 0.5 mm from the surface of the steel sheet and averaging the area ratio at each position.
  • bainite is a structure in which the former austenite grain boundaries are clear, fine lath structures are developed in the grains, and fine carbides and MA are scattered in the laths and between the laths.
  • Tempered bainite is a structure having a lath shape in which carbides are dispersed in the lath and at the lath boundary.
  • Granular bainite is formed at an intermediate transformation temperature between acicular ferrite and bainite and has an intermediate texture.
  • FIG. 3A shows an example of a metal structure imaged by a scanning electron microscope at a position of t / 4 of a steel plate as a base material of the steel pipe according to the present embodiment
  • FIG. 3B shows a base metal part of the steel pipe according to the present embodiment.
  • 1 shows an example of a metal structure imaged by a scanning electron microscope at a surface of a steel sheet of 0.5 mm.
  • Hardness of internal metal structure Maximum hardness: 248 Hv or less Average hardness: 170 to 220 Hv In the steel pipe according to the present embodiment, in order to secure excellent strength, SSC resistance and HIC resistance, the maximum hardness is 248 Hv or less and the average hardness is 170 to 220 Hv in the internal metal structure of the base metal part.
  • the maximum hardness exceeds 248 Hv, the HIC resistance decreases, so the maximum hardness is set to 248 Hv or less. Preferably it is 230 Hv. If the average hardness is less than 170 Hv, required strength cannot be secured, so the average hardness is 170 Hv or more. Preferably it is 180 Hv or more. On the other hand, if the average hardness exceeds 220 Hv, HIC resistance and toughness decrease. Therefore, the average hardness is set to 220 Hv or less. Preferably it is 210 Hv or less.
  • the maximum hardness of the surface layer metal structure 250 Hv or less If the maximum hardness of the surface layer metal structure is more than 250 Hv, the SSC resistance decreases. Therefore, the maximum hardness of the surface layer metal structure is set to 250 Hv or less. Preferably, it is 240 Hv or less.
  • the maximum hardness and the average hardness in the internal metal structure can be measured by the following methods. Using a Vickers hardness tester (load: 100 g), starting at a depth of 1.1 mm from the surface of the steel sheet and extending to the center of the thickness at intervals of 0.1 mm in the thickness direction and 1.0 mm in the width direction for the same depth. Measure hardness at 20 points at intervals. As a result of the above measurement, if two or more measurement points exceeding 248 Hv do not appear continuously in the thickness direction, it is determined that the maximum hardness of the internal metal structure is Hv 248 or less. In the base material of the steel pipe according to the present embodiment, a high hardness value (abnormal value) may appear locally due to inclusions or the like.
  • HIC resistance and SSC resistance can be ensured even if such abnormal values appear.
  • the HIC resistance and / or the SSC resistance are not due to inclusions but are unacceptable. Therefore, in the present embodiment, even if there is one measurement point exceeding 248Hv, if two or more points do not appear continuously in the sheet thickness direction, the point is not adopted as an abnormal point, and is not adopted as an abnormal point. Is the maximum hardness.
  • the highest value is adopted as the maximum hardness. The average hardness is calculated by averaging the hardness of all the measurement points.
  • the measurement of the maximum hardness of the surface layer metal structure from the surface of the steel sheet to a depth of 1.0 mm is performed as follows. First, from the end in the width direction of the steel sheet (corresponding to a butt portion in the case of a steel pipe), a position of 4, ⁇ ⁇ , and ⁇ in the width direction of the steel sheet (in the case of a steel pipe, the welded portion is 0 mm) In the case where it is time, a 300 mm square (300 mm ⁇ 300 mm) steel plate is cut out from the 3 o'clock, 6 o'clock and 9 o'clock positions by gas cutting, and a block test of 20 mm in length and 20 mm in width is performed from the center of the cut out steel plate.
  • Pieces are collected by mechanical cutting and polished by mechanical polishing. Using a Vickers hardness tester (load: 100 g), one block test piece was measured at a point of 0.1 mm from the surface as a starting point, at 10 points at intervals of 0.1 mm in the thickness direction, and at the same depth at intervals of 1.0 mm in the width direction. Points, a total of 100 points are measured. That is, a total of 300 points are measured with three block test pieces. As a result of the above measurement, when two or more measurement points exceeding 250 Hv do not appear continuously in the thickness direction, it is determined that the maximum hardness of the surface layer portion is 250 Hv or less.
  • the degree of integration of ⁇ 100 ⁇ ⁇ 110> is 1.5 or more. Without hot rolling, cooling and reheating. Therefore, the internal metal structure has the above-described texture. Having a texture improves the DWTT characteristics of the steel sheet. Such a texture cannot be obtained when a steel sheet is manufactured by quenching and tempering or when a steel sheet is manufactured by normalizing.
  • the texture can be obtained by the following method. Assuming that the thickness of the steel sheet of the base metal part is t, a 2.0 mm ⁇ 2.0 mm area is defined as 0 mm by using EBSP with respect to a plane parallel to the plate surface at a depth of t / 4 from the surface. The crystal orientation analysis is performed at 1 mm intervals to determine the degree of integration of the (100) ⁇ 110> texture.
  • the thickness of the steel sheet of the base metal part (wall thickness of the steel pipe): 15 mm or less
  • the steel pipe according to the present embodiment is hardened so as to have DWTT characteristics, SSC resistance, and HIC resistance, which have been difficult to satisfy at the same time.
  • This is a steel pipe manufactured without performing a tempering process (rolled and cooled) and using a steel plate having a thickness of 15 mm or less as a base material.
  • the steel pipe according to the present embodiment has excellent SSC resistance and HIC resistance even when the thickness of the steel plate is 12 mm or less.
  • the strength of the base material portion (steel plate according to the present embodiment) of the steel pipe according to the present embodiment is a strength equivalent to 5L-X60 to X70 in the API standard (tensile strength 520 MPa to) in order to ensure the strength as a steel pipe. 760 MPa).
  • the upper limit of the tensile strength is preferably 650 MPa or less in order to secure an overmatch of the welded portion during on-site welding.
  • the steel pipe according to the present embodiment is obtained by processing the steel plate according to the present embodiment into a tubular shape, butting and welding both ends of the tubular steel plate. Therefore, it has the welding part provided in the butting part of a steel plate and extending in the longitudinal direction of a steel plate.
  • the welded portion is constructed so as to be thicker than the base material portion.
  • the weld metal is a higher alloy than the base metal and has high corrosion resistance. Therefore, the weld is rarely the starting point of the destruction. Therefore, the welded portion of the steel pipe according to the present embodiment is not particularly limited as long as it is obtained under normal conditions by SAW welding or the like.
  • the steel pipe according to the present embodiment has the above-described configuration, and the effect can be obtained.
  • the following manufacturing method it is preferable because it can be obtained stably.
  • the steel sheet according to the present embodiment is: (I) A slab satisfying a predetermined chemical composition and Ceq is heated to 1050 to 1250 ° C. and subjected to hot rolling, and finish rolling at 830 to 1000 ° C. to obtain a steel sheet having a thickness of 15 mm or less.
  • Process hot rolling process
  • Ii-1) a step of cooling the steel sheet after rolling from above 750 to 950 ° C. to a temperature range of 660 to 750 ° C. at an average cooling rate of 25 to 100 ° C./sec (first cooling step);
  • the steel pipe according to the present embodiment is: (Iv) a step of forming the steel sheet obtained through the steps (i) to (iii) into a cylindrical shape (forming step); (V) a process of welding both ends of the tubular steel plate by butt welding (welding process); Is obtained by a manufacturing method including: The above temperature is managed by the surface temperature.
  • preferable conditions of each step will be described.
  • the billet heating temperature be 1050 ° C. or higher. More preferably, the temperature is 1100 ° C. or higher.
  • the slab heating temperature exceeds 1250 ° C., the crystal grains become coarse and the low-temperature toughness decreases. Therefore, it is preferable that the billet heating temperature be 1250 ° C. or less. More preferably, it is 1200 ° C or lower. Casting of molten steel and production of billets prior to the hot rolling step may be performed according to a conventional method.
  • Finish rolling temperature 830 to 1000 ° C
  • the heated steel slab is hot-rolled to a steel sheet of 15 mm or less.
  • the finish rolling temperature is preferably set to 830 to 1000 ° C.
  • the finish rolling temperature is 850 ° C. or higher.
  • the finish rolling temperature is preferably set to 1000 ° C. or less. The temperature is more preferably 980 ° C or lower.
  • Cooling start temperature Ts more than 750 to 950 ° C
  • Average cooling rate Vc1 25 to 100 ° C./sec.
  • Cooling stop temperature Tm 660 to 750 ° C.
  • the steel sheet having a surface temperature of Ts (cooling start temperature) in a temperature range of more than 750 to 950 ° C. at an average cooling rate Vc of 25 to 50 ° C./sec.
  • the cooling start temperature Ts is 750 ° C. or less at the surface temperature, the area ratio of ferrite exceeds 15%. In this case, the area ratio of one or both of granular bainite and bainite is less than 85%, and the HIC resistance is reduced. Therefore, the cooling start temperature Ts is preferably set to be higher than 750 ° C. at the surface temperature. It is more preferably at least 800 ° C.
  • the cooling start temperature Ts exceeds 950 ° C., the crystal grains become coarse and the low-temperature toughness decreases. Further, the maximum hardness of the surface layer may be too high. Therefore, it is preferable that the cooling start temperature Ts be 950 ° C. or less at the surface temperature. The temperature is more preferably 930 ° C or lower.
  • the average cooling rate Vc1 is less than 25 ° C./sec, the cooling rate is too slow, and a large amount of ferrite is generated in the surface layer and the internal metal structure, and one or both of granular bainite and bainite having an area ratio of 85% or more. Cannot be obtained, and the SSC resistance and the HIC resistance decrease. Therefore, the average cooling rate Vc1 is preferably set to 25 ° C./sec or more. More preferably, it is 30 ° C./sec or more.
  • the average cooling rate Vc1 exceeds 100 ° C./sec, the maximum hardness exceeds 248 Hv in the internal metal structure, and the HIC resistance decreases. Therefore, the average cooling rate Vc1 is preferably set to 100 ° C./sec or less. More preferably, it is 50 ° C./sec or less, further preferably 45 ° C./sec or less.
  • the cooling stop temperature Tm of the first cooling step is lower than 660 ° C., a large amount of ferrite is generated, and one or both of granular bainite and bainite having an area ratio of 85% or more cannot be obtained. SSC property and HIC resistance decrease. Therefore, the cooling stop temperature Tm is preferably set to 660 ° C. or higher. It is more preferably at least 680 ° C. On the other hand, if the cooling stop temperature Tm exceeds 750 ° C., there is a concern that the surface layer is hardened and the SSC resistance is reduced. Therefore, the cooling stop temperature Tm is preferably set to 750 ° C. or lower. More preferably, it is 720 ° C. or lower.
  • Cooling start temperature Tm 660-750 ° C Average cooling rate Vc2: more than 50 ° C./sec.
  • Cooling stop temperature Tf 400 ° C. or less
  • the first stage cooling stop temperature Tm 660 to 750 ° C. Cool to a cooling stop temperature Tf of 400 ° C. or less.
  • the average cooling rate Vc2 In accelerated cooling from the cooling start temperature Tm of 660 to 750 ° C., if the average cooling rate Vc2 is 50 ° C./sec or less, the internal maximum hardness is increased, and there is a concern that the HIC resistance is reduced. Therefore, it is preferable that the average cooling rate Vc2 be more than 50 ° C./sec. More preferably, it is 60 ° C./sec or more.
  • the upper limit of the average cooling rate Vc2 is not particularly limited, but is about 200 ° C./sec at present because the cooling capacity of the cooling equipment is a practical upper limit.
  • the cooling stop temperature Tf is preferably set to 400 ° C. or lower. More preferably, it is 380 ° C or lower. Since the cooling stop temperature Tf is determined according to the type of steel and the cooling rate, the lower limit is not particularly set. However, it is preferably 250 ° C. or higher from the viewpoint of sufficiently recovering the heat to obtain a required structure and hardness.
  • two-stage accelerated cooling with different cooling rates is performed.
  • Such cooling is performed by adjusting the amount of cooling water injected into the steel sheet for each cooling zone in a cooling facility in which the cooling zone is divided into a plurality of pieces in the longitudinal direction (transport direction) of the steel sheet.
  • the cooling rate is obtained by dividing the temperature difference between the cooling start temperature and the cooling stop temperature by the cooling time.
  • the recuperation rate Vr is less than 50 ° C./sec, there is a concern that the surface layer is hardened and the SSC resistance is reduced. Therefore, the recuperation rate is set to 50 ° C./sec or more.
  • the recuperation rate may be appropriately set in consideration of the time required for the surface temperature of the steel sheet to exceed 550 to 650 ° C., and the upper limit is not particularly limited.
  • the recuperation speed is obtained by dividing the recuperation temperature width by the time required for recuperation.
  • the steel sheet surface temperature after recuperation is 550 ° C. or less, the maximum hardness of the internal structure exceeds 248 Hv, so the steel sheet surface temperature after recuperation is preferably more than 550 ° C. More preferably, it is 580 ° C or higher.
  • the steel sheet surface temperature after reheating exceeds 650 ° C., the average hardness does not reach 170 Hv. Therefore, it is preferable that the surface temperature of the steel sheet after reheating is 650 ° C. or less. The temperature is more preferably 620 ° C or lower.
  • the recuperation rate and the quantity of recuperation vary depending on the temperature difference between the surface and the inside when cooling is stopped.
  • the temperature difference between the surface and the inside is not simply determined by the cooling rate, but changes depending on the water density in water cooling, the collision pressure, and the like. Therefore, the cooling conditions may be determined so that the recuperation rate is 50 ° C./sec or more and the surface temperature after recuperation is more than 550 to 650 ° C. For example, if an experiment for determining conditions is performed in advance, appropriate conditions can be set.
  • FIG. 2 schematically shows an example of a cooling curve of the steel sheet after the finish rolling (change in the steel sheet surface temperature in the first cooling step, the second cooling step, and the recuperation step).
  • the steel sheet after the recuperation step is preferably cooled to an average cooling rate of 0.01 ° C./sec or more and 300 ° C. or less. If the average cooling rate is less than 0.01 ° C./sec, the desired strength cannot be obtained.
  • a steel plate used for the base material portion of the steel pipe according to the present embodiment can be manufactured. That is, the steel sheet according to the present embodiment is a non-heat treated steel.
  • the steel sheet according to the present embodiment obtained in the above process is formed into a tubular shape, and butted portions (both ends in the width direction of the steel plate) of the tubular steel plate are welded to form a steel pipe.
  • the forming of the steel sheet according to the present embodiment into a steel pipe is not limited to a specific forming. Although warm working may be performed, cold working is preferred in terms of dimensional accuracy.
  • the welding is not limited to a specific welding, but a submerged arc welding is preferable.
  • the welding condition may be a known condition according to the thickness of the steel sheet or the like.
  • a heat treatment may be performed on the welded portion in order to improve the toughness of the welded portion.
  • the heat treatment temperature may be in a normal temperature range, but is particularly preferably in a range of 300 to Ac1 point.
  • the pipe according to the present embodiment is a steel pipe having sufficient mechanical properties as a steel pipe for a line pipe in both the base material portion and the welded portion.
  • the conditions in the examples are one condition examples adopted for confirming the feasibility and effects of the present invention, and the present invention is not limited to these one condition examples.
  • the present invention can employ various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.
  • a test piece was sampled from the manufactured steel sheet, and the internal metallographic structure was observed at a magnification of 1000 times from the surface of the steel sheet at a position (t / 4) 1/4 of the plate thickness using a scanning electron microscope. I decided. Further, the surface layer metal structure was obtained by observing and measuring 0.1 mm, 0.2 mm, and 0.5 mm positions from the surface of the steel sheet and averaging the area ratio at each position. Further, a JIS No. 5 tensile test piece was prepared, a tensile test specified in JIS Z 2241 was performed, and the yield strength and the tensile strength were measured.
  • the hardness of the internal metal structure and the surface metal structure was measured with a Vickers hardness tester.
  • a Vickers hardness tester load: 100 g
  • a Vickers hardness tester load: 100 g
  • the highest value is defined as the maximum hardness.
  • the average hardness was calculated by averaging the hardness of all the measurement points.
  • a 300 mm square (300 mm ⁇ 300 mm) steel sheet is cut out from the end in the width direction of the steel sheet by gas cutting, and a block test piece having a length of 20 mm and a width of 20 mm is mechanically cut from the center of the cut steel sheet. And polished by mechanical polishing.
  • one block test piece was measured at a point of 0.1 mm from the surface as a starting point, at 10 points at intervals of 0.1 mm in the thickness direction, and at the same depth at intervals of 1.0 mm in the width direction. Points, a total of 100 points were measured. That is, a total of 300 points were measured with three block test pieces.
  • the point is regarded as an abnormal point, and the next highest value is regarded as the maximum hardness. did.
  • the highest value is defined as the maximum hardness.
  • the NACE test saturates hydrogen sulfide gas in a solution of 5% NaCl solution + 0.5% acetic acid, pH 2.7, immerses the steel sheet in the solution, and observes whether cracks occur after 96 hours. It is a test.
  • the DWTT property (ductile fracture rate at ⁇ 30 ° C.) was evaluated by the following method. DWTT test pieces were sampled from the steel sheet so that the width direction of the steel sheet was parallel to the longitudinal direction of the test piece. The sampling position was 1/4 position in the width direction of the steel sheet. The DWTT test piece was a full thickness test piece with a press notch. The test piece was subjected to a DWTT test at ⁇ 30 ° C. in accordance with API 5L, and the ductile fracture ratio occupying the entire fracture surface was measured. The higher the numerical value of the fracture surface ratio (%), the better the DWTT characteristics. In the present invention, it was determined that the DWTT characteristics were excellent when the ductile fracture ratio was 85% or more.
  • a test piece was collected from the base material of the manufactured steel pipe, and the fraction (area ratio) of each of the surface layer metal structure and the internal metal structure was calculated.
  • the internal metallographic structure was determined by observing the structure at a position (t / 4) 1/4 of the plate thickness from the surface of the steel plate using a scanning electron microscope at a magnification of 1000 times. The remaining structure not described in the table was ferrite.
  • the surface layer metal structure was obtained by measuring positions of 0.1 mm, 0.2 mm, and 0.5 mm from the surface of the steel sheet and averaging the area ratio at each position. Further, a JIS No. 5 tensile test piece was prepared, a tensile test specified in JISZ2241 was performed, and the yield strength and the tensile strength were measured.
  • the hardness of the internal metal structure and the surface metal structure was measured with a Vickers hardness tester.
  • a Vickers hardness tester load: 100 g
  • a Vickers hardness tester load: 100 g
  • the highest value is defined as the maximum hardness.
  • the average hardness was calculated by averaging the hardness of all the measurement points.
  • a 300 mm square (300 mm ⁇ 300 mm) steel plate is cut out from the positions of 3 o'clock, 6 o'clock, and 9 o'clock when the welded portion is set to 0 o'clock from the butt portion of the steel pipe by gas cutting. From the center of the steel plate, a block test piece having a length of 20 mm and a width of 20 mm is collected by mechanical cutting and polished by mechanical polishing.
  • one block test piece was measured at a point of 0.1 mm from the surface as a starting point, at 10 points at intervals of 0.1 mm in the thickness direction, and at the same depth at intervals of 1.0 mm in the width direction. Points, a total of 100 points were measured. That is, a total of 300 points were measured with three block test pieces.
  • the point is regarded as an abnormal point, and the next highest value is regarded as the maximum hardness. did.
  • the highest value is defined as the maximum hardness.
  • test piece was sampled from the base material portion of the manufactured steel pipe, and the following test was performed to evaluate the HIC resistance and the SSC resistance.
  • HIC resistance A test based on NACE (National Association of Corrosion and Engineer) TM0284 was performed, and the presence or absence of HIC (hydrogen induced cracking) was observed. The case where the HIC property was excellent (OK) was evaluated, and the case where the HIC fracture ratio was more than 5% was evaluated as poor (NG) when the HIC resistance was poor.
  • NACE National Association of Corrosion and Engineer
  • the NACE test saturates hydrogen sulfide gas in a solution of 5% NaCl solution + 0.5% acetic acid, pH 2.7, immerses the steel sheet in the solution, and observes whether cracks occur after 96 hours. It is a test.
  • the DWTT characteristics were evaluated by the following method. DWTT test pieces were sampled from the steel pipe such that the circumferential direction of the steel pipe was parallel to the longitudinal direction of the test piece. The sampling position was 90 ° from the seam position of the steel pipe. Here, the DWTT test piece was a full thickness test piece with a press notch. The test piece was subjected to a DWTT test at ⁇ 30 ° C. in accordance with API 5L, and the ductile fracture ratio occupying the entire fracture surface was measured. The higher the numerical value of the fracture surface ratio (%), the better the DWTT characteristics. In the present invention, it was determined that the DWTT characteristics were excellent when the ductile fracture ratio was 85% or more.
  • ADVANTAGE OF THE INVENTION even if it does not use additional elements, such as V, Cu, Ni, and / or Mo, it has the intensity

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

L'invention concerne un tuyau d'acier comprenant une partie de matériau de base, qui est composée d'une tôle d'acier tubulaire présentant une composition chimique spécifiée, et une partie de soudure qui est disposée au niveau d'une partie de jonction bout à bout de la tôle d'acier et qui s'étend dans la direction de la longueur de la tôle d'acier, la structure métallique interne contenant de la bainite granulaire et/ou de la bainite à un rapport surfacique total supérieur ou égal à 85 % et contenant également de la MA à un rapport surfacique inférieur ou égal à 1,0 %, la dureté maximale et la dureté moyenne dans la structure métallique interne étant inférieure ou égale à 248 Hv et de 170 à 220 Hv, respectivement, la partie de matériau de base présentant une texture présentant un degré d'intégration {100}<110> supérieur ou égal à 1,5 sur un plan qui est parallèle à une surface de tôle positionnée à une profondeur de 1/4 à partir de la surface susmentionnée telle qu'observée dans la direction de l'épaisseur de la tôle, la structure métallique dans une partie de couche de surface contenant de la bainite granulaire et/ou de la bainite revenue à un rapport surfacique total supérieur ou égal à 95 %, la structure métallique dans la partie de couche de surface présentant une dureté maximale inférieure ou égale à 250 Hv et l'épaisseur de la tôle d'acier étant inférieure ou égale à 15 mm.
PCT/JP2018/024839 2018-06-29 2018-06-29 Tuyau d'acier et tôle d'acier Ceased WO2020003499A1 (fr)

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KR1020217001704A KR102457409B1 (ko) 2018-06-29 2018-06-29 강관 및 강판
CN201880094993.XA CN112313357B (zh) 2018-06-29 2018-06-29 钢管和钢板
PCT/JP2018/024839 WO2020003499A1 (fr) 2018-06-29 2018-06-29 Tuyau d'acier et tôle d'acier
JP2018556509A JP6460297B1 (ja) 2018-06-29 2018-06-29 鋼管及び鋼板
EP18923989.0A EP3816311B1 (fr) 2018-06-29 2018-06-29 Tuyau d'acier et tôle d'acier

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JP2024021561A (ja) * 2022-08-04 2024-02-16 Ｊｆｅスチール株式会社 ４０キロ級非調質型厚鋼板、溶接鋼管およびそれらの製造方法
EP4234743A4 (fr) * 2020-10-23 2024-12-04 POSCO Co., Ltd Tôle d'acier à haute résistance présentant une excellente stabilité thermique, et son procédé de fabrication
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JP7335492B2 (ja) * 2019-06-07 2023-08-30 日本製鉄株式会社 ラインパイプ用鋼板および鋼管
EP4006180A4 (fr) * 2019-07-31 2022-10-12 JFE Steel Corporation Feuille d'acier à haute résistance pour tuyau de canalisation résistant à l'acidité, procédé de fabrication correspondant et tuyau d'acier à haute résistance utilisant une feuille d'acier à haute résistance pour tuyau de canalisation résistant à l'acidité
CN114846163B (zh) * 2020-01-17 2023-10-24 日本制铁株式会社 钢板和钢管
CN112375968B (zh) * 2020-10-20 2022-04-08 包头钢铁（集团）有限责任公司 一种旋挖钻机钻杆用热轧钢带的生产方法
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WO2021193383A1 (fr) * 2020-03-26 2021-09-30 Ｊｆｅスチール株式会社 Tôle d'acier à haute résistance pour tuyau de canalisation résistant à l'acidité, procédé de fabrication correspondant et tuyau d'acier à haute résistance utilisant une tôle d'acier à haute résistance pour tuyau de canalisation résistant à l'acidité
JP7264269B2 (ja) 2020-03-26 2023-04-25 Ｊｆｅスチール株式会社 耐サワーラインパイプ用高強度鋼板およびその製造方法並びに耐サワーラインパイプ用高強度鋼板を用いた高強度鋼管
EP4129510A4 (fr) * 2020-03-26 2025-01-29 JFE Steel Corporation Tôle d'acier à haute résistance pour tuyau de canalisation résistant à l'acidité, procédé de fabrication correspondant et tuyau d'acier à haute résistance utilisant une tôle d'acier à haute résistance pour tuyau de canalisation résistant à l'acidité
EP4234743A4 (fr) * 2020-10-23 2024-12-04 POSCO Co., Ltd Tôle d'acier à haute résistance présentant une excellente stabilité thermique, et son procédé de fabrication
JP7396551B1 (ja) * 2022-06-21 2023-12-12 Ｊｆｅスチール株式会社 耐サワーラインパイプ用高強度鋼板及びその製造方法並びに耐サワーラインパイプ用高強度鋼板を用いた高強度鋼管
WO2023248638A1 (fr) * 2022-06-21 2023-12-28 Ｊｆｅスチール株式会社 Tôle d'acier haute résistance pour un tuyau de canalisation résistant à l'acidité, ainsi que son procédé de production, et tuyau en acier haute résistance utilisant une tôle d'acier haute résistance pour un tuyau de canalisation résistant à l'acidité
JP2024021561A (ja) * 2022-08-04 2024-02-16 Ｊｆｅスチール株式会社 ４０キロ級非調質型厚鋼板、溶接鋼管およびそれらの製造方法
JP7670004B2 (ja) 2022-08-04 2025-04-30 Ｊｆｅスチール株式会社 ４０キロ級非調質型厚鋼板、溶接鋼管およびそれらの製造方法
WO2025197997A1 (fr) * 2024-03-22 2025-09-25 Ｊｆｅスチール株式会社 Matériau d'acier, et procédé de fabrication de celui-ci
JPWO2025197997A1 (fr) * 2024-03-22 2025-09-25
JP7816653B1 (ja) 2024-03-22 2026-02-18 Ｊｆｅスチール株式会社 鋼材および鋼材の製造方法

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KR102457409B1 (ko) 2022-10-24
CN112313357A (zh) 2021-02-02
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EP3816311A1 (fr) 2021-05-05

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