WO2016056216A1 - Tôle d'acier pour tube de canalisation, procédé pour la fabrication de cette dernière et tube d'acier pour tube de canalisation - Google Patents

Tôle d'acier pour tube de canalisation, procédé pour la fabrication de cette dernière et tube d'acier pour tube de canalisation Download PDF

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WO2016056216A1
WO2016056216A1 PCT/JP2015/005046 JP2015005046W WO2016056216A1 WO 2016056216 A1 WO2016056216 A1 WO 2016056216A1 JP 2015005046 W JP2015005046 W JP 2015005046W WO 2016056216 A1 WO2016056216 A1 WO 2016056216A1
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toughness
mass
less
steel
strength
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PCT/JP2015/005046
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English (en)
Japanese (ja)
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仁 末吉
石川　信行
遠藤　茂
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Ｊｆｅスチール株式会社
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Priority to BR112017007136-3A priority Critical patent/BR112017007136B1/pt
Priority to JP2016552822A priority patent/JP6288288B2/ja
Publication of WO2016056216A1 publication Critical patent/WO2016056216A1/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
    • 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
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron

Definitions

  • the present invention relates to a high-strength steel sheet for line pipes particularly excellent in hydrogen-induced crack resistance and a method for producing the same.
  • HIC resistance hydrogen-induced cracking resistance
  • SCC resistance stress corrosion cracking resistance
  • sour resistance is required.
  • Hydrogen-induced cracking in steel (hereinafter also referred to as HIC) is a phenomenon in which hydrogen ions are adsorbed on the surface of the steel by a corrosion reaction, penetrate into the steel as atomic hydrogen, and nonmetallic inclusions such as MnS in the steel and hard metal It is said that it diffuses and accumulates around the two-phase structure and raises the internal pressure there to induce cracking.
  • Patent Document 1 and Patent Document 2 describe the reduction of elements with high segregation tendency (C, Mn, P, etc.), soaking in the slab heating stage, and transformation during cooling.
  • a steel with excellent HIC resistance that suppresses the formation of hardened structures such as island martensite, the origin of cracks in the center segregation part, martensite, bainite, etc. It is disclosed.
  • Patent Document 3 suppresses the formation of acicular MnS by adding an appropriate amount of Ca or Ce to the amount of S, and changes the form of MnS to stress concentration.
  • Patent Document 4 and Patent Document 5 have excellent HIC resistance by suppressing the formation of polygonal ferrite and coarse NbC by controlling the amount of C and the amount of Mn or Nb together with the addition of an appropriate amount of Ca. Steel is disclosed.
  • High-strength steel sheets used for line pipes are often manufactured by so-called TMCP technology using controlled rolling and accelerated cooling.
  • the microstructure of the high-strength steel sheet obtained by this accelerated cooling may be a relatively high cracking sensitive structure such as bainite or acicular ferrite. In that case, it is important to suppress the formation of coarse block bainite and island martensite with high cracking sensitivity, particularly in the center segregation portion.
  • All the methods for improving the HIC resistance reported in the above patent documents are intended to suppress cracking at the center segregation part, but in order to improve the HIC resistance of high-strength steel sheets, the center segregation is reduced. However, it is still insufficient and more strict segregation suppression is required.
  • the object of the present invention is a line pipe that solves such problems of the prior art, has excellent resistance to hydrogen-induced cracking in the center segregation part, and fully utilizes the strength and toughness improvement effects of TMCP. It is to provide a steel plate.
  • the gist configuration of the present invention is as follows. 1. % By mass C: 0.02 to 0.10%, Si: 0.01-0.50% Mn: 0.10 to 1.0% P: 0.015% or less, S: 0.0020% or less, Ca: 0.0002 to 0.0050%, Nb: 0.03-0.15%, Ti: 0.002 to 0.070%, Al: 0.002 to 0.080% and N: 0.001 to 0.008%
  • the CP value (mass%) represented by the following formula (1) is 0.85 or less, and the ratio of Mn amount to Nb amount [Mn] / [Nb] is within the range satisfying the following formula (2).
  • a steel sheet for line pipes characterized in that the balance has a component composition of Fe and inevitable impurities, and has a structure mainly composed of bainite.
  • CP 4.46 [C] + 2.37 [Mn] / 6 + 22.36 [P] (1) 0.8 ⁇ [Mn] / [Nb] ⁇ 25 (2)
  • [] shows the content (mass%) of the element in the parenthesis, and the element not added is 0.
  • CP 4.46 [C] +2.37 [Mn] / 6 + [1.74 [Cu] +1.7 [Ni]] / 15+ [1.18 [Cr] +1.95 [Mo] +1.74 [V]] / 5 + 22. 36 [P] (3)
  • [] shows the content (mass%) of the element in the parenthesis, and the element not added is 0.
  • B 0.0002 to 0.005%
  • REM 0.0002 to 0.050%
  • Mg 0.0002 to 0.005%
  • PCM [C] + [Si] / 30 + [Mn] / 20 + [Cu] / 20 + [Ni] / 60 + [Cr] / 20 + [Mo] / 15 + [V] / 10 + 5 [B] ... (4)
  • [] shows the content (mass%) of the element in the parenthesis, and the element not added is 0.
  • the steel slab having the component composition described in any one of 1 to 5 above is heated to a temperature of 1000 to 1300 ° C. and hot-rolled at a rolling finish temperature not lower than the Ar 3 temperature, and then (Ar 3 ⁇ 10 ° C.)
  • a method for producing a steel plate for a line pipe characterized in that cooling is performed from the above temperature to a temperature range of 200 to 600 ° C. at a cooling rate of 5 ° C./s or more.
  • a steel pipe for a line pipe comprising the steel plate according to any one of 1 to 5 above.
  • the present invention it is possible to provide a steel plate for a line pipe having high strength and high toughness and excellent HIC resistance.
  • the steel pipe using the steel plate for line pipes of the present invention has high strength and toughness and excellent HIC resistance, and therefore is extremely suitable for transporting crude oil and natural gas containing hydrogen sulfide.
  • the inventors diligently studied the components and microstructure of the steel material and the manufacturing method of the steel sheet in order to achieve both improvement in HIC resistance of the high-strength steel sheet and increase in strength and toughness. That is, as a component system that suppresses segregation while ensuring high strength and lowers cracking susceptibility, optimize the CP value considering segregation, and the microstructure is a uniform fine bainite structure utilizing transformation strengthening. To obtain the knowledge that is very effective. That is, it has been found that cracking from the central segregation portion can be suppressed by strictly controlling the content of alloy components that are easily segregated and optimizing the component composition with the CP value.
  • High-strength steel sheets having a bainite structure with low Mn and effective use of Nb as described above center segregation is remarkably reduced and a uniform microstructure is obtained, and coarse block bainite and island martensite with high cracking sensitivity
  • the formation of MnS inclusions is remarkably suppressed and the resistance to cracking is extremely high, and the generation of HIC can be suppressed.
  • a steel sheet having a uniform and fine bainite structure in which central segregation is significantly reduced has low cracking susceptibility of the welded portion, and can improve the weld heat affected zone toughness.
  • the steel plate for line pipes according to the present invention will be described in detail.
  • the component composition and the metal structure (microstructure), which will be described in order from the component composition are important to define the component composition and the metal structure (microstructure), which will be described in order from the component composition.
  • Si 0.01-0.50% Si is added for deoxidation, but if it is less than 0.01%, a sufficient deoxidation effect cannot be obtained. On the other hand, if the Si content exceeds 0.50%, the base metal toughness and weld heat-affected zone toughness are deteriorated, so the range is 0.01 to 0.50%. From the viewpoint of weld heat-affected zone toughness, it is preferably 0.01 to 0.40%.
  • Mn 0.10 to 1.0%
  • Mn is an important element in the present invention. That is, Mn is added to ensure strength and toughness, but if it is less than 0.10%, the effect cannot be sufficiently obtained. On the other hand, if the amount of Mn exceeds 1.0%, center segregation becomes obvious, the segregation part hardens during accelerated cooling, and the weld heat affected zone toughness and HIC resistance may deteriorate.
  • Mn is an element that is a main cause of center segregation. Lowering Mn makes it possible to significantly reduce center segregation and suppress the formation of MnS inclusions, thereby improving HIC resistance. Therefore, Mn is in the range of 0.10 to 1.0%.
  • the preferable amount of Mn is 0.10 to 0.80%. Further, from the viewpoint of ensuring strength and toughness and reducing the manufacturing cost, the preferable amount of Mn is 0.20 to 0.80%. More preferably, it is 0.30 to 0.80%.
  • P 0.015% or less
  • P is an inevitable impurity element that deteriorates weldability and increases the hardness of the central segregation part to deteriorate the weld heat-affected zone toughness and HIC resistance. In the range not exceeding 0.015%, that is, 0.015% or less. In particular, from the viewpoint of HIC resistance, the preferable amount of P is 0.010% or less.
  • S 0.0020% or less S is generally better because it becomes MnS inclusions in steel and deteriorates HIC resistance. Moreover, since S segregates at the grain boundary and lowers the grain boundary strength, the base metal toughness and the weld heat affected zone toughness are deteriorated. If S is reduced to 0.0020% or less, deterioration of HIC resistance and toughness due to S are hardly observed, so the amount of S is limited to 0.0020% or less. From the viewpoint of HIC resistance, it is preferably 0.0010% or less.
  • Ca 0.0002 to 0.0050%
  • Ca is an element effective for improving HIC resistance by controlling the form of sulfide inclusions, but if it is less than 0.0002%, the effect is not sufficiently exhibited. On the other hand, even if added over 0.0050%, the above effect is saturated, but rather the HIC resistance is deteriorated due to a decrease in the cleanliness of the steel. Therefore, Ca is in the range of 0.0002 to 0.0050%. From the viewpoint of HIC resistance, it is preferably 0.0005 to 0.0040%.
  • Nb 0.03-0.15%
  • Nb is an extremely important element in the present invention.
  • the strength can be effectively increased by utilizing transformation enhancement, and the structure can be refined.
  • Nb is an element effective for strengthening transformation and expanding the non-recrystallized region, the effect of transformation strengthening and microstructure refinement by TMCP is increased.
  • the increase in transformation strengthening and the fine graining of the structure due to the addition of high Nb can improve the strength and toughness, and also enable high-efficiency production by high-temperature rolling. However, if it is less than 0.03%, the effect cannot be obtained sufficiently.
  • Nb is set in the range of 0.03 to 0.15%.
  • the preferable amount of Nb is 0.04 to 0.15%. More preferably, it is 0.05 to 0.15%.
  • the viewpoint of fully utilizing the effect of expanding the non-recrystallized region and transformation strengthening by Nb, and suppressing the deterioration of HIC resistance and the deterioration of the base metal toughness and the weld heat affected zone toughness preferably 0.07 to 0.12 %.
  • Ti 0.002 to 0.070%
  • Ti is an element that contributes to an increase in strength, an improvement in base metal toughness, and an improvement in weld heat affected zone toughness.
  • Ti is effective as an element that forms precipitates with N, suppresses grain growth in a high temperature region, and improves the weld heat affected zone toughness.
  • 0.002% or more is added.
  • the upper limit is made 0.070%. From the viewpoint of weld heat-affected zone toughness, it is preferably 0.005 to 0.050%.
  • Al 0.002 to 0.080% Al is added as a deoxidizer, but less than 0.002% has no effect. On the other hand, if it exceeds 0.080%, the cleanliness of the steel decreases, and the base metal toughness and the weld heat affected zone toughness deteriorate, so the range is 0.002 to 0.080%. From the viewpoint of base metal toughness and weld heat-affected zone toughness, it is preferably 0.010 to 0.060%.
  • N 0.001 to 0.008%
  • N is an element that forms a precipitate with Ti and suppresses grain growth in a high temperature range and contributes to improvement of the toughness of the weld heat affected zone. If the N content is less than 0.001%, the above effects cannot be obtained sufficiently. On the other hand, if it exceeds 0.008% and is added excessively, the weld heat-affected zone toughness is deteriorated and there is a risk of causing slab cracking in the steelmaking stage. Therefore, N is in the range of 0.001 to 0.008%. From the viewpoint of weld heat-affected zone toughness, it is preferably 0.002 to 0.006%.
  • CP 4.46 [C] + 2.37 [Mn] / 6 + 22.36 [P] (1)
  • [] shows the content (mass%) of the element in the parenthesis, and the element not added is 0.
  • the CP value represented by the above formula (1) is used to estimate the material of the central segregation part from the content of each alloy element.
  • the CP value is 0.85 or less, so that coarse block bainite and island martensite with high cracking sensitivity are obtained.
  • the formation of MnS inclusions is remarkably suppressed and the resistance to cracking is extremely high, and the generation of HIC can be suppressed.
  • the upper limit is desirably set to 0.80.
  • a more preferable CP value is 0.75 or less.
  • Mn is an element that is a main cause of center segregation and promotes hardening of the center segregation part, leading to deterioration of HIC resistance and weld heat affected zone toughness.
  • Nb is an element that effectively contributes to the increase in transformation strengthening and refinement of the structure.
  • Mn segregates Nb is also easily segregated, so that coarse Nb precipitates are present in the hardened central segregation part. Concerns remain.
  • the ratio of the amount of Mn and the amount of Nb is in the range of 0.8 ⁇ [Mn] / [Nb] ⁇ 25. From the viewpoint of HIC resistance and weld heat-affected zone toughness, 2.0 ⁇ [Mn] / [Nb] ⁇ 20 is preferable. More preferably, 4.0 ⁇ [Mn] / [Nb] ⁇ 16.
  • the above is the basic component composition of the present invention. If it is necessary to further improve the strength, base metal toughness and weld heat affected zone toughness of the steel sheet, Cu: 0.01 to 0.50%, Ni: 0.01 One or two or more selected from ⁇ 0.50%, Cr: 0.01 to 0.50%, Mo: 0.01 to 0.50%, and V: 0.002 to 0.10% may be contained.
  • Cu 0.01-0.50%
  • Cu is an element effective for improving the base material toughness and increasing the strength, and for that purpose, it is preferably added at 0.01% or more.
  • the upper limit is 0.50%.
  • Ni 0.01-0.50%
  • Ni is an element effective for improving the base metal toughness and increasing the strength, and for that purpose, it is preferable to add at 0.01% or more.
  • the upper limit is 0.50%.
  • Cr 0.01-0.50% Cr is an element effective for improving the base metal toughness and increasing the strength, and for that purpose, it is preferably added at 0.01% or more. On the other hand, since weldability deteriorates when added in excess, the upper limit is made 0.50% when adding Cr.
  • Mo 0.01-0.50% Mo is an element effective for improving the base material toughness and increasing the strength, and for that purpose, it is preferably added at 0.01% or more. On the other hand, since weldability deteriorates when added in excess, the upper limit is 0.50% when Mo is added.
  • V 0.002 to 0.10%
  • V is an element effective for increasing the strength.
  • V is preferably added in an amount of 0.002% or more.
  • the upper limit is made 0.10%.
  • the above-described CP value is calculated according to the following formula (3), and the CP value is designed to be within a component range of 0.85 or less as described above It is essential. If higher HIC resistance is required, the upper limit of the CP value is desirably 0.80. More preferably, it is 0.75 or less.
  • CP 4.46 [C] +2.37 [Mn] / 6 + [1.74 [Cu] +1.7 [Ni]] / 15+ [1.18 [Cr] +1.95 [Mo] +1.74 [V]] / 5 + 22. 36 [P] (3) However, [] shows the content (mass%) of the element in the parenthesis, and the element not added is 0.
  • B 0.0002 to 0.005%
  • REM 0.0002 to 0.050%
  • Mg 0.0002 to 0.005%
  • B 0.0002 to 0.005%
  • B is an element that contributes to an increase in strength.
  • B is preferably added in an amount of 0.0002% or more.
  • the upper limit is made 0.005%.
  • REM 0.0002 to 0.050% REM is an element that improves the weld heat-affected zone toughness.
  • REM is preferably added in an amount of 0.0002% or more.
  • the upper limit is 0.050%.
  • Mg 0.0002 to 0.005%
  • Mg is an element that improves the weld heat-affected zone toughness, and for that purpose, it is preferably added at 0.0002% or more. On the other hand, if added excessively, the weld heat affected zone toughness deteriorates, so when adding Mg, the upper limit is made 0.005%.
  • the above component composition is preferably designed in a component range in which the PCM value (mass%) represented by the following formula (4) is 0.16 or less.
  • PCM [C] + [Si] / 30 + [Mn] / 20 + [Cu] / 20 + [Ni] / 60 + [Cr] / 20 + [Mo] / 15 + [V] / 10 + 5 [B] (4)
  • [] shows the content (mass%) of the element in the parenthesis, and the element not added is 0.
  • the PCM value represented by the above formula (4) is a weld cracking sensitivity index, and by setting the component composition such that the PCM value is 0.16 or less, good weld heat affected zone toughness can be ensured. From the viewpoint of weld heat affected zone toughness, it is preferably 0.14 or less. More preferably, it is 0.12 or less.
  • the above-described component composition is further designed in a component range where [Ti] / [N], which is the ratio of the Ti amount to the N amount, satisfies the following formula (5).
  • [Ti] / [N] which is the ratio of the Ti amount to the N amount, satisfies the following formula (5).
  • [Ti] / [N] ⁇ 4.0
  • [] shows the content (mass%) of the element in the parenthesis, and the element not added is 0.
  • Ti and N improve the weld heat affected zone toughness by generating TiN precipitates and suppressing the coarsening of crystal grains in the weld zone.
  • the correlation between both the Ti content and the N content is important. That is, when [Ti] / [N] is less than 1.0, the formation of TiN precipitates is insufficient and the crystal grains become coarse, so that the weld heat affected zone toughness decreases. Moreover, when [Ti] / [N] exceeds 4.0, TiN precipitates are coarsened, the pinning effect at the crystal grain boundaries is lowered, and the coarsening of the crystal grains cannot be suppressed, so that the weld heat affected zone toughness deteriorates.
  • HIC resistance deteriorates.
  • weld heat affected zone toughness preferably 1.5 ⁇ [Ti] / [N] ⁇ 4.0. More preferably, 2.0 ⁇ [Ti] / [N] ⁇ 4.0.
  • the remainder other than the above consists of Fe and inevitable impurities.
  • the content of other trace elements is not hindered unless the effects of the present invention are impaired.
  • As an inevitable impurity for example, O: 0.0030% or less is acceptable.
  • the metal structure of the high-strength steel sheet of the present invention is a structure mainly composed of bainite. This is because a steel sheet having a two-phase structure tends to accumulate hydrogen at the two-phase interface, and the two-phase interface becomes a crack propagation path and is inferior in HIC resistance. It is important to be an organization.
  • the bainite structure of the steel sheet of the present invention has a remarkable reduction in center segregation as described above, so there is no generation of coarse block bainite or island martensite with high cracking sensitivity even in the center segregation part. It has a uniform bainite structure.
  • the bainite structure of the steel sheet of the present invention is a uniform fine bainite structure transformed during accelerated cooling, and has excellent strength and toughness due to transformation strengthening.
  • the steel sheet having a uniform and fine bainite structure in which the central segregation of the present invention is remarkably reduced has low cracking sensitivity, excellent strength, base metal toughness and weld heat affected zone toughness, and excellent HIC resistance.
  • the bainite structure in the present invention includes a structure called bainitic ferrite or granular ferrite that transforms during or after accelerated cooling that contributes to transformation strengthening.
  • ferrite generated at a temperature equal to or lower than the cooling start temperature at the time of accelerated cooling or after accelerated cooling has a bainitic transformation behavior in a supercooled state, and thus has excellent strength and toughness by transformation strengthening. That is, bainitic ferrite and granular ferrite produced during or after accelerated cooling are superior in strength and toughness compared to ordinary polygonal ferrite in which grain boundaries produced before accelerated cooling are smooth and clear.
  • the total of the metal structures other than the bainite structure should be less than 5% in volume fraction.
  • the structure mainly composed of bainite in the present invention means that the bainite phase is 95% or more.
  • the island-like martensite (MA) is more preferably 3% or less.
  • the ferrite classified into metal structures other than a bainite structure here is a ferrite produced
  • the temperature is an average temperature in the thickness direction of the slab or steel plate.
  • slab heating temperature 1000-1300 °C
  • the slab heating temperature is less than 1000 ° C., the solid solution of the carbide is insufficient and the required strength cannot be obtained. In addition, the remaining coarse carbides deteriorate the base metal toughness and HIC resistance. On the other hand, when the temperature exceeds 1300 ° C., the crystal grain size becomes coarse and the base metal toughness deteriorates.
  • the slab heating temperature is more preferably 1050 to 1250 ° C.
  • the hot rolling end temperature is not less than the Ar 3 point which is the ferrite transformation start temperature during cooling. That is, when the rolling end temperature is less than the Ar 3 point, ferrite remains and a two-phase structure is formed, so that the HIC resistance is deteriorated. From the viewpoint of production efficiency, rolling at a high temperature is better, and the rolling end temperature is preferably 800 ° C. or higher.
  • This Ar 3 point can be obtained by the following equation (6).
  • Ar 3 910-310 [C] -80 [Mn] -20 [Cu] -15 [Cr] -55 [Ni] -80 [Mo] (6) However, [] shows the content (mass%) of the element in the parenthesis, and the element not added is 0.
  • cooling is performed from a temperature of (Ar 3 ⁇ 10 ° C.) or higher to a temperature range of 200 to 600 ° C. at a cooling rate of 5 ° C./s or higher. That is, if cooling or slow cooling is performed after completion of rolling, sufficient transformation strengthening cannot be obtained, so accelerated cooling is performed.
  • Arbitrary equipment can be used as the cooling equipment and does not need to be specified.
  • the cooling start temperature is set to (Ar 3 ⁇ 10 ° C.) or higher. From the viewpoint of achieving both strength and HIC resistance, the cooling start temperature is more preferably Ar 3 or higher.
  • the cooling rate after rolling is more preferably 10 ° C./s or more. Further, if the cooling rate is too high, the center segregation part may be cured and the cracking susceptibility may be increased. Therefore, from the viewpoint of HIC resistance, the upper limit of the cooling rate is preferably 60 ° C./s.
  • Step pipe Line pipe suitable for transporting crude oil and natural gas by forming the above steel sheet for line pipe into a tubular shape by press bend forming, roll forming, UOE forming, etc., and then welding, and further expanding the pipe as necessary.
  • Steel pipes (UOE steel pipes, ERW steel pipes, spiral steel pipes, etc.) can be manufactured.
  • UOE steel pipe the edge part of a steel plate is grooved, and after forming into a ring shape by C press, U press, O press, the groove part is welded by temporary welding and inner / outer surface welding, and undergoes a pipe expanding process.
  • a steel pipe for a line pipe made of the above-described steel sheet for a line pipe is excellent in strength, base metal toughness and weld heat affected zone toughness, has low cracking sensitivity even in a sour environment, and has excellent HIC resistance.
  • the tensile properties were measured by conducting a tensile test using a full thickness test piece in the rolling vertical direction as a tensile test piece, and measuring the tensile strength.
  • the base metal toughness was evaluated by the DWTT test (falling weight characteristic) at ⁇ 30 ° C.
  • the weld heat affected zone toughness was subjected to a Charpy test using a test piece to which a heat history corresponding to a maximum heating temperature of 1400 ° C. and a heat input of 40 kJ / cm was added by a reproducible heat cycle apparatus.
  • HIC resistance is determined by performing an HIC test with a soaking time of 96 hours according to NACE Standard TM-02-84.
  • the target range of the present invention is a DWTT test at a tensile strength of 520 MPa or more as a high-strength steel sheet in consideration of manufacturing variations, a microstructure (microstructure) mainly composed of bainite, and a base metal toughness at ⁇ 30 ° C.
  • the ductile fracture surface ratio was 85% or more, the weld heat affected zone toughness was 50% or more in the Charpy test at -30 ° C, and no cracks were found in the HIC test.
  • Nos. 1 to 18 are examples of the present invention, all of which are composed mainly of bainite, have good HIC resistance, have a tensile strength of 520 MPa or more, and a ductile fracture surface ratio of 85% in the DWTT test. As described above, the ductile fracture surface ratio in the Charpy test of the weld heat affected zone is 50% or more.
  • Nos. 19 to 22 are comparative examples in which the chemical components satisfy the conditions of the present invention but the manufacturing conditions do not satisfy the present invention. And weld heat-affected zone toughness and HIC resistance are inferior.
  • No.19 is mainly composed of bainite because the slab heating temperature is low, the solid solution of Nb, which is important for transformation strengthening in the bainite transformation, is insufficient and the tensile strength is low, and the cooling stop temperature is high. A structure cannot be obtained, and strength and base material toughness are reduced.
  • the hot rolling conditions and accelerated cooling conditions do not satisfy the conditions of the present invention, so that a structure mainly composed of bainite cannot be obtained and the strength is insufficient, or ferrite and island martensite (MA ) And pearlite precipitate, the base metal toughness, weld heat affected zone toughness, and HIC resistance are inferior.
  • Nos. 23 to 31 have inferior base metal toughness, weld heat affected zone toughness, and HIC resistance because the chemical components do not satisfy the conditions of the present invention.

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Abstract

　L'invention concerne une tôle d'acier pour un tube de canalisation, ayant une excellente résistance à la fissuration provoquée par l'hydrogène d'une partie séparée du centre et dans laquelle les effets d'amélioration de la résistance et la ténacité d'un traitement thermomécanique TMCP sont adéquatement utilisés. La composition de la présente invention est principalement de bainite et contient, en % en masse et selon une relation prédéfinie, 0,02 à 0,10 % de C, 0,01 à 0,50 % de Si, 0,10 à 1,0 % de Mn, 0,015 % ou moins de P, 0,0020 % ou moins de S, 0,0002 à 0,0050 % de Ca, 0,03 à 0,15 % de Nb, 0,002 à 0,070 % de Ti, 0,002 à 0,080 % d'Al et 0,001 à 0,008 % de N.
PCT/JP2015/005046 2014-10-07 2015-10-02 Tôle d'acier pour tube de canalisation, procédé pour la fabrication de cette dernière et tube d'acier pour tube de canalisation WO2016056216A1 (fr)

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JPWO2018179512A1 (ja) * 2017-03-30 2019-04-18 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
WO2018179512A1 (fr) * 2017-03-30 2018-10-04 Ｊｆｅスチール株式会社 Plaque d'acier haute résistance pour tuyau de canalisation résistant à l'acidité, son procédé de fabrication, et tuyau en acier haute résistance utilisant une plaque d'acier haute résistance pour tuyau de canalisation résistant à l'acidité
WO2020202333A1 (fr) * 2019-03-29 2020-10-08 Ｊｆｅスチール株式会社 Tube d'acier soudé par résistance électrique ainsi que procédé de fabrication de celui-ci, et pieu tubulaire en acier
JP6690787B1 (ja) * 2019-03-29 2020-04-28 Ｊｆｅスチール株式会社 電縫鋼管およびその製造方法、並びに鋼管杭
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CN114174547A (zh) * 2019-07-31 2022-03-11 杰富意钢铁株式会社 耐酸性管线管用高强度钢板及其制造方法以及使用耐酸性管线管用高强度钢板的高强度钢管
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
RU2788419C1 (ru) * 2019-07-31 2023-01-19 ДжФЕ СТИЛ КОРПОРЕЙШН Высокопрочный стальной лист для сероводородостойкой магистральной трубы, способ его изготовления и высокопрочная стальная труба, полученная с использованием высокопрочного стального листа для сероводородостойкой магистральной трубы
JP7272442B2 (ja) 2019-07-31 2023-05-12 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
WO2021100534A1 (fr) * 2019-11-20 2021-05-27 Ｊｆｅスチール株式会社 Tôle d'acier laminée à chaud pour tuyau en acier électrosoudé et son procédé de production, tuyau en acier électrosoudé et son procédé de production, canalisation et structure d'immeuble
JPWO2021100534A1 (ja) * 2019-11-20 2021-12-02 Ｊｆｅスチール株式会社 電縫鋼管用熱延鋼板およびその製造方法、電縫鋼管およびその製造方法、ラインパイプ、建築構造物
CN110983184A (zh) * 2019-12-17 2020-04-10 邯郸钢铁集团有限责任公司 一种低碳tmcp态船板钢及其生产方法

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