WO2010093057A1 - Tôle d'acier haute résistance et tuyau en acier haute résistance ayant une excellente résistance au craquage induit par l'hydrogène pour une utilisation dans un tuyau de canalisation - Google Patents

Tôle d'acier haute résistance et tuyau en acier haute résistance ayant une excellente résistance au craquage induit par l'hydrogène pour une utilisation dans un tuyau de canalisation Download PDF

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WO2010093057A1
WO2010093057A1 PCT/JP2010/052483 JP2010052483W WO2010093057A1 WO 2010093057 A1 WO2010093057 A1 WO 2010093057A1 JP 2010052483 W JP2010052483 W JP 2010052483W WO 2010093057 A1 WO2010093057 A1 WO 2010093057A1
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steel
hydrogen
segregation
amount
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Japanese (ja)
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原卓也
寺田好男
村木太郎
鈴木豪
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新日本製鐵株式会社
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Priority to CN2010800075239A priority Critical patent/CN102317491A/zh
Priority to KR1020137023805A priority patent/KR101524397B1/ko
Priority to BRPI1008563A priority patent/BRPI1008563A2/pt
Publication of WO2010093057A1 publication Critical patent/WO2010093057A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • 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
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • 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
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron

Definitions

  • the present invention relates to a steel plate for a line pipe and a steel pipe for a line pipe, which are excellent in hydrogen-induced cracking resistance (referred to as HIC resistance), which is optimal for applications such as oil and natural gas transportation line pipes.
  • HIC resistance hydrogen-induced cracking resistance
  • HIC hydrogen-induced cracking
  • Patent Documents 1 to 3 Mn is an element that easily segregates at the center of a steel sheet, and methods for suppressing the segregation of Mn have been proposed (for example, Patent Documents 1 to 3).
  • Patent Document 1 proposes a steel sheet in which the ratio of the Mn content of the segregation part to the average Mn content in the steel is suppressed.
  • Patent Documents 2 and 3 propose a high-strength line pipe that limits the P concentration of the segregation part in addition to the size of the Mn segregation spot and further utilizes Ca.
  • hot rolled steel sheets with excellent HIC resistance have been proposed that focus on Nb segregation (for example, Patent Document 4).
  • methods for suppressing inclusions such as carbides and nitrides of Ti and Nb have been proposed (for example, Patent Documents 5 and 6).
  • the present invention has been made in view of such circumstances, and is suitable for steel pipes used for transportation line pipes of petroleum, natural gas, etc., and has excellent HIC resistance and steel pipe for line pipes and line pipes The issue is to provide steel pipes.
  • the present inventors conducted earnest research on conditions necessary for obtaining a steel sheet for high-strength line pipe and a steel pipe for high-strength line pipe excellent in hydrogen-induced crack resistance with a tensile strength of 500 MPa or more, and new ultra-high strength It came to invent the steel plate for line pipes and the steel pipe for high-strength line pipes.
  • the gist of the present invention is as follows.
  • Ni 0.01 to 2.0%
  • Cu 0.01 to 1.0%
  • Cr 0.01 to 1.0%
  • Mo 0.01 to 1.0%
  • W 0.01 to 1.0%
  • V 0.01 to 0.10%
  • Zr 0.0001 to 0.050%
  • Ta 0.0001 to 0.050%
  • B 0.0001 to 0.0020%
  • the steel plate for high-strength line pipes having excellent resistance to hydrogen-induced cracking as described in (1) above, wherein one or more of the above are contained, and the balance is iron and inevitable impurities.
  • the base material is mass%, C: 0.02 to 0.08%, Si: 0.01 to 0.5%, Mn: 1.0 to 1.6% Nb: 0.001 to 0.10%, Ca: 0.0001 to 0.0050%, N: 0.0010 to 0.0050%, O: 0.0001 to 0.0030% Containing P: 0.01% or less, S: 0.0020% or less, Al: 0.030% or less, Ti: limited to 0.030% or less, S, Ca content, S / Ca ⁇ 0.5 And the balance consists of Fe and inevitable impurity elements, And the steel pipe for high intensity
  • the base material is mass%, Ni: 0.01 to 2.0%, Cu: 0.01 to 1.0%, Cr: 0.01 to 1.0%, Mo: 0.01 to 1.0%, W: 0.01 to 1.0%, V: 0.01 to 0.10% Zr: 0.0001 to 0.050%, Ta: 0.0001 to 0.050%, B: 0.0001 to 0.0020%
  • the steel pipe for high-strength line pipes having excellent resistance to hydrogen-induced cracking as described in (6) above, wherein one or more of the above are contained, and the balance consists of iron and inevitable impurities.
  • the base material is mass%, REM: 0.0001 to 0.01%, Mg: 0.0001 to 0.01%, Y: 0.0001 to 0.005%, Hf: 0.0001 to 0.005%, Re: 0.0001 to 0.005%
  • the steel pipe for high-strength line pipe excellent in hydrogen-induced crack resistance according to (6) or (7) above, further comprising one or more of them.
  • the maximum Mn segregation degree of the base material 2.0 or less, Nb segregation degree: 4.0 or less, Ti segregation degree: 4.0 or less,
  • the segregation degree of Mn, Nb, Ti decreases, the length of the non-crimped portion of the center segregation portion and the increase in the maximum hardness are suppressed, and the steel plate for line pipe excellent in hydrogen-induced crack resistance.
  • industrial contributions such as the production of steel pipes for line pipes are extremely remarkable.
  • FIG. 1 is a diagram showing the relationship between the S / Ca content ratio S / Ca and the CAR in the HIC test.
  • the present inventors performed a NACE (National Association of Corrosion and Engineer) test using various steel plates for line pipes, and evaluated the presence or absence of HIC.
  • the NACE test is a test method in which hydrogen sulfide gas is saturated in a solution of 5% NaCl solution + 0.5% acetic acid, pH 2.7 to investigate whether cracks are generated after 96 hours. After the test, a test piece was collected from the cracked steel plate, and the location where HIC was generated was observed in detail. As a result, it was found that the unbonded portion of the central segregation portion is a particularly important HIC starting point.
  • This unseparated portion of the center segregation portion needs to have a length of 0.1 mm or less. This is because the fracture surface of the crack in which the HIC occurred after the NACE test was observed with a scanning electron microscope (SEM), and the minimum length of the uncompressed portion was more than 0.1 mm. It is a rule based.
  • the non-crimped part means that the gap generated in the steel piece during solidification is not crimped by hot rolling and remains in the steel plate, and when the size is large, the length is measured by nondestructive inspection such as ultrasonic waves. be able to.
  • the cause of the unbonded part remaining in the center segregation part is hydrogen contained in the steel slab before hot rolling.
  • the steel When the steel is melted by a converter and secondary refining and then continuously cast, the steel solidifies and is cooled and contracts, so that a void is generated particularly at the center of the steel slab.
  • this void has a negative pressure, if the amount of hydrogen in the steel slab is large, hydrogen gas enters the void.
  • the amount of hydrogen contained in the steel when melted by secondary refining remains almost as it is in the voids in the steel slab after continuous casting.
  • the structure of the steel slab is austenite, and hydrogen is not easily diffused out of the steel slab.
  • austenite is a face-centered cubic crystal and a large amount of hydrogen can be dissolved.
  • the voids in the steel slab become smaller, but the pressure of the hydrogen gas contained in the voids increases in inverse proportion to the size of the voids. For this reason, the gap cannot be crimped even by hot rolling, and an uncompressed portion remains on the steel plate.
  • the steel sheet is cooled, and when the metal structure is transformed from austenite to ferrite, bainite, martensite, pearlite, etc., hydrogen is diffused to the outside. Therefore, the amount of hydrogen remaining on the steel sheet is lower than the amount of hydrogen after secondary refining.
  • FIG. 1 shows the relationship between CAR (crack area ratio) and S / Ca in the HIC test of 0.04% C-1.25% Mn steel.
  • CAR crack area ratio
  • S / Ca the S / Ca content ratio
  • FIG. 1 shows the relationship between CAR (crack area ratio) and S / Ca in the HIC test of 0.04% C-1.25% Mn steel.
  • S / Ca ratio when the S / Ca ratio is 0.5 or more, HIC starts to be generated, and it is understood that S / Ca needs to be less than 0.5.
  • the O content 0.0030% or less and the Al content 0.030% or less. It has been clarified that when the amount of O is large, coarse oxides are easily accumulated, and when Al is added in an amount of more than 0.030%, Al oxide clusters are easily accumulated.
  • the maximum Mn segregation degree of the steel sheet and the steel pipe is 2.0 or less, and in addition to these, carbonitriding of accumulated Ti and Nb. It has been found that the occurrence of HIC in the steel pipe for line pipe and the steel pipe for line pipe can be remarkably prevented by restraining the object. In order to suppress accumulation of carbonitrides of Ti and Nb, it is preferable to satisfy the following conditions.
  • the N content is 0.0050% or less
  • the C content is 0.06% or less
  • the segregation degrees of Nb and Ti are each 4 or less.
  • the maximum Mn segregation degree is the ratio of the maximum Mn amount of the center segregation portion to the average Mn amount excluding the center segregation portion in the Mn amount of the steel plate and the steel pipe, that is, (the maximum Mn of the center segregation portion). Amount) / (average amount of Mn excluding the central segregation part).
  • the Nb segregation degree and the Ti segregation degree are ratios of the average Nb amount (Ti amount) of the central segregation portion to the average Nb amount (Ti amount) excluding the central segregation portion of the steel plate and the steel pipe.
  • the maximum degree of Mn segregation is determined by measuring the Mn concentration distribution of steel plates and steel pipes using EPMA (Electron Probe Micro Analyzer) or CMA (Computer Aided Micro Analyzer) capable of image processing the measurement results by EPMA. Can do.
  • EPMA Electro Probe Micro Analyzer
  • CMA Computer Aided Micro Analyzer
  • the numerical value of the maximum Mn segregation degree varies depending on the probe diameter of EPMA (or CMA).
  • the present inventors have found that the segregation of Mn can be properly evaluated by setting the probe diameter (beam diameter) to 2 ⁇ m. Actually, the measurement is performed as follows.
  • the Mn concentration in a region of 1 mm (width) ⁇ 1 mm (thickness) is further measured with a beam diameter of 2 ⁇ m at the place where the Mn amount is most concentrated (center segregation portion).
  • the maximum Mn segregation degree is obtained from this Mn concentration distribution.
  • data of 500 points ⁇ 500 points are accumulated.
  • the ratio of the maximum Mn concentration of the 250,000 points to the average Mn concentration excluding the central segregation portion was defined as the maximum Mn segregation degree, and the value was obtained.
  • the Nb segregation degree and the Ti segregation degree can be determined by measuring the Nb concentration distribution and the Ti concentration distribution, respectively, by EPMA or CMA.
  • the Nb segregation degree and the maximum Ti segregation degree it was found that the segregation can be appropriately evaluated by setting the beam diameter to 2 ⁇ m.
  • the maximum hardness of the central segregation part of the steel plate and the steel pipe in which segregation of Mn, Nb, and Ti is suppressed is 300 Hv or less.
  • the upper limit of the center segregation portion maximum hardness is 300 Hv, generation of HIC can be reliably prevented.
  • Mn and Nb are elements that enhance the hardenability, and Ti contributes to precipitation strengthening. Therefore, by suppressing the segregation of these elements, the hardening of the central segregation part can be suppressed.
  • the central segregation part is a part where the concentration of Mn measured by EPMA or CMA becomes maximum, and the maximum hardness of the central segregation part conforms to JIS Z 2244 after corroding with 3% nitric acid + 97% nital solution. Then, a Vickers hardness test may be performed with a load of 25 g.
  • C is an element that improves the strength of steel, and as its effective lower limit, addition of 0.02% or more is necessary. On the other hand, if the amount of C exceeds 0.08%, the formation of carbides is promoted and the HIC resistance is impaired, so the upper limit is made 0.08%. Further, in order to suppress a decrease in HIC property, weldability, and toughness, the C content is preferably 0.06% or less.
  • Si Si is a deoxidizing element and needs to be added in an amount of 0.01% or more. On the other hand, if the Si content exceeds 0.5%, the toughness of the weld heat affected zone (HAZ) is lowered, so the upper limit is made 0.5%.
  • Mn Mn is an element that improves strength and toughness, and it is necessary to add 1.0% or more. On the other hand, if the amount of Mn exceeds 1.6%, the HAZ toughness is lowered, so the upper limit is made 1.6%. In order to suppress HIC, the Mn content is preferably less than 1.5%.
  • Nb Nb is an element that forms carbides and nitrides and contributes to improvement in strength. In order to obtain the effect, it is necessary to add 0.001% or more. However, if Nb is added excessively, the degree of segregation of Nb increases, and the accumulation of Nb carbonitrides is invited, resulting in a decrease in HIC resistance. Therefore, in the present invention, the upper limit of the Nb amount is 0.10%. In consideration of HIC properties, the Nb content is preferably 0.05% or less.
  • N is an element that forms nitrides such as TiN and NbN.
  • the lower limit of the N amount is 0.0010%. It is necessary to. However, if the N content exceeds 0.0050%, Ti and Nb carbonitrides are likely to accumulate, and the HIC resistance is impaired. Therefore, the upper limit of the N amount is set to 0.0050%. In addition, when toughness etc. are requested
  • P is an impurity. If the content exceeds 0.01%, the HIC resistance is impaired, and the toughness of the HAZ is lowered.
  • the P content is limited to 0.01% or less.
  • S is an element that reduces the HIC resistance by generating MnS that extends in the rolling direction during hot rolling. Therefore, in the present invention, it is necessary to reduce the amount of S, and the content is limited to 0.0020% or less. In order to improve toughness, the S content is preferably 0.0010% or less. The smaller the amount of S, the better. However, it is difficult to make it less than 0.0001%, and it is preferable to contain 0.0001% or more from the viewpoint of manufacturing cost.
  • Ti is an element that is usually used for grain refinement as a deoxidizer or nitride-forming element. In the present invention, an element that lowers HIC resistance and toughness by forming carbonitrides. It is. Therefore, the Ti content is limited to 0.030% or less.
  • Al Al is a deoxidizing element. However, in the present invention, when the addition amount exceeds 0.030%, an accumulation cluster of Al oxide is confirmed, so it is limited to 0.030% or less. When toughness is required, the upper limit of Al content is preferably set to 0.017% or less. Although the lower limit of the amount of Al is not particularly limited, it is preferable to add Al in an amount of 0.0005% or more in order to reduce the amount of oxygen in the molten steel.
  • O is an impurity, and the content is limited to 0.0030% or less in order to suppress the accumulation of oxides and improve the HIC resistance. In order to suppress the formation of oxides and improve the base material and the HAZ toughness, the O content is preferably 0.0020% or less.
  • Ca is an element that generates sulfide CaS, suppresses the generation of MnS extending in the rolling direction, and contributes significantly to the improvement of HIC resistance. If the addition amount of Ca is less than 0.0001%, the effect cannot be obtained, so the lower limit is set to 0.0001%. A content of 0.0005% or more is preferable. On the other hand, if the amount of Ca exceeds 0.0050%, oxides accumulate and the HIC resistance is impaired, so the upper limit is made 0.0050%. In the present invention, since S is fixed by adding Ca to form CaS, the ratio of S / Ca in the content of S and Ca is an important index.
  • Ni is an element effective in improving toughness and strength, and in order to obtain the effect, addition of 0.01% or more is necessary. However, addition over 2.0% causes HIC and weldability. Therefore, the upper limit is preferably made 2.0%.
  • Cu is an element effective for increasing the strength without reducing toughness, but if it is less than 0.01%, there is no effect, and if it exceeds 1.0%, cracking is likely to occur during heating of the steel slab or during welding. To do. Therefore, the content is preferably 0.01 to 1.0%.
  • the upper limit is preferably 1.0%.
  • Mo Mo is an element that improves hardenability and at the same time forms carbonitrides and improves strength. To obtain the effect, addition of 0.01% or more is preferable. On the other hand, if Mo is added in a large amount exceeding 1.0%, the cost increases, so the upper limit is preferably made 1.0%. Moreover, since the HIC property and the toughness may decrease when the strength of the steel increases, the more preferable upper limit is made 0.20%.
  • W W is an element effective for improving the strength, and is preferably added in an amount of 0.01% or more. On the other hand, when W exceeding 1.0% is added, the toughness may be lowered, so the upper limit is preferably made 1.0%.
  • V V is an element that forms carbides and nitrides and contributes to improvement in strength. In order to obtain the effect, addition of 0.01% or more is preferable. On the other hand, if V exceeding 0.10% is added, the toughness may be lowered, so the upper limit is preferably made 0.10%.
  • Zr, Ta: Zr and Ta are elements that form carbides and nitrides as well as V and contribute to the improvement of strength. In order to obtain the effect, it is preferable to add 0.0001% or more. On the other hand, if Zr and Ta are added excessively in excess of 0.050%, the toughness may be reduced, so the upper limit is preferably made 0.050%.
  • B B is an element that segregates at the grain boundaries of steel and contributes significantly to improving the hardenability. In order to obtain this effect, 0.0001% or more of B is preferably added. Further, B is an element that generates BN, lowers the solid solution N, and contributes to the improvement of the toughness of the weld heat affected zone. Therefore, addition of 0.0005% or more is more preferable. on the other hand. When B is added excessively, segregation to the grain boundary becomes excessive and the toughness may be lowered, so the upper limit is preferably made 0.0020%.
  • REM REM is an element added as a deoxidizer and a desulfurizer, and 0.0001% or more is preferably added.
  • Mg Mg is an element added as a deoxidizing agent and a desulfurizing agent. In particular, a fine oxide is generated and contributes to improvement of HAZ toughness.
  • 0.0001% or more of Mg is preferably added.
  • Mg is added in an amount exceeding 0.010%, the oxide tends to aggregate and coarsen, which may lead to deterioration in HIC properties and toughness of the base material and HAZ. Therefore, it is preferable that the amount of Mg added is 0.010% or less.
  • Y, Hf, Re: Y, Hf, and Re are elements that, like Ca, generate sulfides, suppress the generation of MnS elongated in the rolling direction, and contribute to improvement in HIC resistance. In order to obtain such an effect, it is preferable to add 0.0001% or more of Y, Hf, and Re.
  • the addition amount is preferably 0.0050% or less.
  • the cause of the unbonded portion remaining in the center segregation portion is hydrogen contained in the steel slab before hot rolling. Therefore, the pressure of the hydrogen gas contained in the voids in the steel slab can be reduced by reducing the amount of hydrogen in the secondary refining.
  • the amount of H in secondary refining is 0.00025% or less, there is almost no uncompressed part after hot rolling, and even if it exists, the length can be made 0.1 mm or less.
  • the hydrogen partial pressure can be reduced by blowing inert gas, nitrogen, or the like into the atmosphere.
  • the maximum Mn segregation degree, Nb segregation degree, and Ti segregation degree in the base material of a steel plate and a steel pipe are 2.0 or less, 4.0 or less, and 4.0 or less, respectively.
  • the maximum Mn segregation degree is 2.0 or less, generation of coarse MnS is suppressed, and generation of HIC starting from MnS stretched in the rolling direction can be prevented.
  • the Nb segregation degree is 4.0 or less
  • the formation of accumulated Nb (C, N) is suppressed
  • the Ti segregation degree is 4.0 or less
  • the formation of accumulated TiN is suppressed, and the HIC property is deteriorated. Can be prevented.
  • the maximum Mn segregation degree is the ratio of the maximum Mn amount of the central segregation portion to the average Mn amount excluding the central segregation portion of the steel plate and steel pipe, and the Mn concentration of the steel plate and steel pipe by EPMA or CMA with a beam diameter of 2 ⁇ m. Distribution can be measured and determined. The same applies to the degree of Nb segregation and the degree of Ti segregation. The Nb concentration distribution and the Ti concentration distribution were measured by EPMA or CMA with a beam diameter of 2 ⁇ m, respectively, and the average Nb excluding the central segregation portion of the steel plate and the steel pipe was measured.
  • the ratio of the average amount of Nb of the center segregation part to the amount (Nb segregation degree), the ratio of the average Ti amount of the center segregation part to the average Ti amount excluding the center segregation part of the steel plate and steel pipe (Ti segregation degree) Is to be sought.
  • a method for suppressing the maximum Mn segregation degree, Nb segregation degree, and Ti segregation degree will be described below.
  • light reduction at the time of final solidification in continuous casting is optimal.
  • the light reduction at the time of final solidification is applied to eliminate the mixing of solidified and unsolidified parts due to non-uniform cooling of the casting. it can.
  • the steel slab In continuous casting, the steel slab is usually water-cooled, but the end in the width direction is cooled quickly, and the cooling in the center in the width direction is strengthened. Therefore, even if the steel piece is solidified at the end portion and the center portion in the width direction, solidification is delayed at a quarter portion in the width direction, and an unsolidified portion remains inside the steel piece.
  • the solidified part and the unsolidified part are not uniform, and for example, the shape of the interface between the solidified part and the unsolidified part may be W-shaped in the width direction. If such non-uniform solidification occurs in the width direction, segregation is promoted and the HIC resistance is deteriorated.
  • the steel containing the above components is melted in a steelmaking process, and then made into a steel slab by continuous casting.
  • the steel slab is reheated and subjected to thick plate rolling to obtain a steel plate.
  • the reheating temperature of the steel slab is 950 ° C. or higher
  • the reduction ratio in the recrystallization temperature region is 2 or more
  • the reduction ratio in the non-recrystallization region is 3 or more
  • the average prior austenite particle size can be 20 ⁇ m or less.
  • water cooling is performed after completion of rolling, it is preferable to start the water cooling from a temperature of 750 ° C. or higher and stop the water cooling in a temperature range of 400 to 500 ° C.
  • the recrystallization temperature range is a temperature range where recrystallization occurs after rolling, and is generally over 900 ° C. for the components of the steel of the present invention.
  • the non-recrystallization temperature range is a temperature range in which recrystallization and ferrite transformation do not occur after rolling, and is generally 750 to 900 ° C. for the steel components used in the present invention.
  • Rolling in the recrystallization temperature range is called recrystallization rolling or rough rolling
  • rolling in the non-recrystallization temperature range is called non-recrystallization rolling or finish rolling.
  • the maximum hardness of center segregation can be reduced to 300 Hv or lower as described below.
  • the water cooling start temperature is less than 750 ° C.
  • C carbon
  • the austenite phase enriched with C is transformed into hard martensite containing a large amount of C.
  • the hardness can be suppressed to 300 Hv or less.
  • the water cooling stop temperature is set to 400 ° C. or higher, similarly, the hard martensite after transformation is partially decomposed, and the hardness can be suppressed to 300 Hv or lower.
  • strength will fall when water-cooling stop temperature is too high, 500 degrees C or less is preferable.
  • Tensile test pieces, HIC test pieces, and macro test pieces were collected from the obtained steel plates and steel pipes and used for each test.
  • the HIC test was performed according to NACETM0284.
  • the segregation degree of Mn, Nb, and Ti was measured by EPMA using a macro test piece.
  • the concentration distribution of Mn, Nb, and Ti is measured with a 50 ⁇ m beam system in a total thickness ⁇ 20 mm width measurement area, and then each element in the specimen thickness direction is concentrated. The concentration of each element was measured in a 1 mm ⁇ 1 mm region with a 2 ⁇ m beam system at the location (center segregation part).
  • the Vickers hardness of center segregation was measured according to JIS Z 2244. Vickers hardness was measured at a site where the load was 25 g and the Mn concentration was highest in the distribution of Mn concentration in the thickness direction measured by EPMA.
  • Table 2 shows the plate thickness, maximum Mn segregation degree, Nb segregation degree, Ti segregation degree, length of the non-crimped part, maximum hardness of the central segregation part, respectively, obtained from steels 1 to 34 of Table 1.
  • required by tensile strength and the HIC test is shown.
  • Table 3 shows the thickness of the steel pipe obtained from each of the steels 1 to 34 shown in Table 1, the heat input of the main welding, and the area ratio of cracks determined by the HIC test.
  • the maximum Mn segregation degree, Nb segregation degree, Ti segregation degree, length of unbonded part, and maximum hardness of the central segregation part of steel pipe are the same as steel sheet, and the tensile strength of steel pipe is 1-5% that of steel sheet. It is getting bigger.
  • Steels 1 to 23 are examples of the present invention, and the steel sheets obtained from these steels have a maximum Mn segregation degree of 1.6 or less, a Nb segregation degree of 4.0 or less, a Ti segregation degree of 4.0 or less, The maximum hardness of the center segregation part is 300 Hv or less, and no cracks are generated by the HIC test.
  • steels 24 to 34 represent comparative examples that are outside the scope of the present invention. That is, since any element of the basic components is outside the scope of the present invention, the CAR is over 3% in the HIC test.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

La présente invention concerne une tôle d'acier et un tuyau en acier ayant une excellente résistance au craquage induit par l'hydrogène, lesquels sont idéaux, par exemple, pour un tuyau de canalisation utilisé pour acheminer du pétrole ou du gaz naturel. La tôle d'acier et le tuyau en acier sont formés à partir d'acier dont la composition comprend: C: 0,02 à 0,08%, Si: 0,01 à 0,5%, Mn: 1,0 à 1,6%, Nb: 0,001 à 0,10%, Ca: 0,0001 à 0,0050%, N: 0,0010 à 0,0050%, et O: 0,0001 à 0,0030%, P: 0,01% ou moins, S: 0,0020% ou moins, Al: 0,030% ou moins, et Ti: 0,030% ou moins et répond au rapport S/C a < 0,5, et ayant une portion non pressée de la partie au niveau de laquelle la ségrégation s'opère d'une longueur égale ou inférieure à 0,1 mm.
PCT/JP2010/052483 2009-02-12 2010-02-12 Tôle d'acier haute résistance et tuyau en acier haute résistance ayant une excellente résistance au craquage induit par l'hydrogène pour une utilisation dans un tuyau de canalisation WO2010093057A1 (fr)

Priority Applications (3)

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CN2010800075239A CN102317491A (zh) 2009-02-12 2010-02-12 抗氢致开裂性优异的高强度管线管用钢板和高强度管线管用钢管
KR1020137023805A KR101524397B1 (ko) 2009-02-12 2010-02-12 내수소 유기 균열성이 우수한 고강도 라인 파이프용 강판 및 고강도 라인 파이프용 강관
BRPI1008563A BRPI1008563A2 (pt) 2009-02-12 2010-02-12 chapa de aço de alta resistência e tubo de aço de alta resistência para oleoduto excelente em resistência á fratura induzida pelo hidrogênio

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JP2009-030314 2009-02-12
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JP2009253147A JP5423323B2 (ja) 2009-02-12 2009-11-04 耐水素誘起割れ性に優れた高強度ラインパイプ用鋼板及び高強度ラインパイプ用鋼管

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EP2612946A1 (fr) * 2010-09-03 2013-07-10 Nippon Steel & Sumitomo Metal Corporation Tôle d'acier à haute résistance présentant d'excellents résultats de résistance à la rupture et de résistance à la fissuration induite par hydrogène
EP2832879A4 (fr) * 2012-03-30 2016-01-13 Nippon Steel & Sumitomo Metal Corp Tuyau d'acier à haute résistance pour tuyau de canalisation ayant une excellente résistance à la fissuration induite par hydrogène, tuyau d'acier à haute résistance pour tuyau de canalisation l'utilisant et son procédé de fabrication
JP2020503445A (ja) * 2016-12-22 2020-01-30 ポスコＰｏｓｃｏ 耐水素誘起割れ性に優れた引張強度４５０ＭＰａ級の厚肉鋼材及びその製造方法

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JPWO2010104165A1 (ja) * 2009-03-12 2012-09-13 住友金属工業株式会社 耐ｈｉｃ厚鋼板およびｕｏｅ鋼管
WO2011027900A1 (fr) * 2009-09-02 2011-03-10 新日本製鐵株式会社 Tôle d'acier à haute résistance et tuyau en acier à haute résistance présentant une ténacité à basse température supérieure destinés à être utilisés dans des tubes de canalisation
JP5131715B2 (ja) * 2009-09-09 2013-01-30 新日鐵住金株式会社 低温靭性に優れた高強度ラインパイプ用鋼板及び高強度ラインパイプ用鋼管
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JP5824401B2 (ja) * 2012-03-30 2015-11-25 株式会社神戸製鋼所 耐水素誘起割れ性に優れた鋼板およびその製造方法
KR101982014B1 (ko) 2012-06-18 2019-05-24 제이에프이 스틸 가부시키가이샤 후육 고강도 내사우어 라인 파이프, 그의 제조 방법 및 그의 내hic성능의 판정 방법
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JP2016125137A (ja) * 2014-12-26 2016-07-11 株式会社神戸製鋼所 耐水素誘起割れ性に優れた鋼板およびラインパイプ用鋼管
JP6584912B2 (ja) * 2014-12-26 2019-10-02 株式会社神戸製鋼所 耐水素誘起割れ性に優れた鋼板およびラインパイプ用鋼管
JP6642118B2 (ja) * 2016-03-02 2020-02-05 日本製鉄株式会社 耐サワー鋼板
JP6869151B2 (ja) * 2016-11-16 2021-05-12 株式会社神戸製鋼所 鋼板およびラインパイプ用鋼管並びにその製造方法
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CN108456834B (zh) * 2018-03-05 2020-04-24 白婷婷 一种具有含Ti析出物的高强度管线钢及其制备方法
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2612946A1 (fr) * 2010-09-03 2013-07-10 Nippon Steel & Sumitomo Metal Corporation Tôle d'acier à haute résistance présentant d'excellents résultats de résistance à la rupture et de résistance à la fissuration induite par hydrogène
EP2612946A4 (fr) * 2010-09-03 2014-03-26 Nippon Steel & Sumitomo Metal Corp Tôle d'acier à haute résistance présentant d'excellents résultats de résistance à la rupture et de résistance à la fissuration induite par hydrogène
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EP2832879A4 (fr) * 2012-03-30 2016-01-13 Nippon Steel & Sumitomo Metal Corp Tuyau d'acier à haute résistance pour tuyau de canalisation ayant une excellente résistance à la fissuration induite par hydrogène, tuyau d'acier à haute résistance pour tuyau de canalisation l'utilisant et son procédé de fabrication
JP2020503445A (ja) * 2016-12-22 2020-01-30 ポスコＰｏｓｃｏ 耐水素誘起割れ性に優れた引張強度４５０ＭＰａ級の厚肉鋼材及びその製造方法

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KR20130105941A (ko) 2013-09-26
BRPI1008563A2 (pt) 2016-03-15
CN102317491A (zh) 2012-01-11
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