WO2016068094A1 - Tôle d'acier à haute résistance à la traction, présentant une excellente résilience aux basses températures de zones de soudage affectées thermiquement, et son procédé de production - Google Patents

Tôle d'acier à haute résistance à la traction, présentant une excellente résilience aux basses températures de zones de soudage affectées thermiquement, et son procédé de production Download PDF

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WO2016068094A1
WO2016068094A1 PCT/JP2015/080154 JP2015080154W WO2016068094A1 WO 2016068094 A1 WO2016068094 A1 WO 2016068094A1 JP 2015080154 W JP2015080154 W JP 2015080154W WO 2016068094 A1 WO2016068094 A1 WO 2016068094A1
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mass
toughness
less
steel sheet
steel
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Japanese (ja)
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克行 一宮
長谷　和邦
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JFE Steel Corp
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JFE Steel Corp
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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 of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
    • C21D8/02—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
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese

Definitions

  • the present invention relates to a high-tensile steel plate used for steel structures such as ships, offshore structures, pressure vessels, and penstocks, and a method for producing the same.
  • the thickness is 35 to 100 mm
  • the yield stress YS is 460 MPa or more
  • the present invention relates to a thick high-strength steel sheet that not only excels in strength and toughness characteristics of the material, but also has excellent low-temperature toughness in a multi-layer weld zone, and a method for producing the same.
  • Steel plates used for steel structures such as ships, offshore structures, pressure vessels, and penstocks are finished by welding and joining as desired structures and dimensions. Therefore, from the viewpoint of ensuring safety as a steel structure, these steel plates have not only high strength of the base metal and excellent toughness, but also of welded parts (welded metal and heat affected zone). It is required to have excellent toughness.
  • CTOD test CrackCrTip Opening Displacement Test
  • This test is intended to evaluate the resistance to brittle fracture by bending a specimen with fatigue precracking in the toughness evaluation section at three points and measuring the amount of crack opening (plastic deformation) just before fracture. Is.
  • CTOD value the evaluation result obtained in the “CTOD test” is also referred to as “CTOD value” or “CTOD characteristic”.
  • the boundary between the base metal and the heat affected zone is close to the above bond, and is reheated to the two-phase region during multi-layer welding (coarse grains are formed in the first cycle welding, and heat input by subsequent welding)
  • the region reheated to the two-phase region of ferrite and austenite hereinafter also referred to as “two-phase region reheating portion” is likely to be a local embrittlement region. This is because the heat-affected zone in the vicinity of the bond part is exposed to a high temperature just below the melting point, and the austenite grains become coarse, and an upper bainite structure with lower toughness is likely to be formed during subsequent cooling. The toughness of the affected area is reduced. Moreover, in the two-phase region reheated part near the bond part of the heat-affected part, brittle structures such as a Woodman Stetten structure and island martensite MA are likely to be generated, so that the toughness is further reduced.
  • Patent Document 1 and Patent Document 2 a rare earth element (REM: Rare Earth Metal) is added together with Ti, and fine particles are dispersed in steel, thereby austenite grain growth. Techniques for suppressing and improving the toughness of the weld are disclosed. In addition, the technology of finely dispersing Ti oxide in steel, the technology of combining BN ferrite nucleation ability and oxide dispersion, and further adding Ca and REM to control the form of sulfide, Techniques for increasing toughness have also been proposed. However, these technologies are intended for steel sheets with relatively low strength and a small amount of alloying elements. For high-tensile steel sheets where the amount of alloying elements is large and the structure of the heat affected zone does not contain ferrite. It cannot be applied.
  • REM Rare Earth Metal
  • the two-phase region reheating part is a reheating to the two-phase region during multi-layer welding, in which carbon is concentrated in a region reversely transformed into austenite, and a brittle bainite structure including island martensite is formed during cooling. Since it is produced, there is a problem that toughness is lowered. Therefore, a technique is disclosed in which the steel component is made low C, low Si to suppress the formation of island martensite to improve toughness, and further, by adding Cu, the base material strength is increased (for example, (See Patent Documents 3 and 4). These techniques are intended to increase the strength by precipitating Cu by aging treatment. However, since a large amount of Cu is added, there is a problem that hot workability is lowered and productivity is hindered.
  • steel structures such as ships, offshore structures, pressure vessels, and penstocks have tended to increase in size, and accordingly, steel sheets used for steel structures have been made thicker and stronger. It has been.
  • the steel plates used for steel structures are mainly thick steel plates with a thickness of about 35 to 100 mm.
  • the addition of alloying elements is required. Larger amounts are advantageous.
  • the addition of a large amount of the alloy element makes it difficult to ensure the toughness of the bond portion and the two-phase region reheated portion.
  • Patent Document 5 discloses a technique for optimizing the addition amounts of Mn and Cr in order to reduce the island-like martensite MA in the two-phase region reheating portion of the heat affected zone.
  • this technology is related to steel materials for large heat input welding with a heat input of over 500 kJ / cm, and is not intended for steel sheets that are multilayered and welded with small to medium heat input with a heat input of 100 kJ / cm or less. Absent.
  • the technique of patent document 5 does not add Nb, there is a problem that the control rolling technique cannot be applied and the toughness of the base material is not sufficient.
  • Patent Document 6 describes that by optimizing the carbon equivalent Ceq under a predetermined component composition, a yield stress of 420 MPa or more and good low-temperature toughness, particularly CTOD characteristics, even for a steel component with a large amount of alloy elements.
  • a technique for achieving both has been proposed. This technique makes it possible to produce a high-tensile steel material suitable for use in a steel structure having a yield stress of 420 MPa or more and excellent in the CTOD characteristics of a heat-affected zone multilayer welded by small to medium heat input.
  • steel structures tend to be heavy and long, and accordingly, in the field of ships and marine structures, high strength (high yield stress), thick plate thickness, and welding heat
  • high strength high yield stress
  • thick plate thickness thick plate thickness
  • welding heat There is a growing demand for steel plates having excellent low temperature toughness in the affected zone, in particular, steel plates having a yield stress of 460 MPa or more, a plate thickness of 35 to 100 mm, and a CTOD characteristic in which a multilayer heat-welded weld heat affected zone is excellent.
  • the technique disclosed in Patent Document 6 described above is a method for realizing a yield stress of 420 MPa or more and good low temperature toughness (CTOD characteristics) even in a steel component system having many alloy elements.
  • CTOD characteristics good low temperature toughness
  • steel sheets having a thickness of more than 50 mm have not yet achieved the same strength characteristics as those of steel sheets having a thickness of 50 mm or less. That is, in the technique described in Patent Document 6, a steel sheet having a thickness of 50 mm or less can provide a strength with a yield stress of 500 MPa or more.
  • a steel sheet with a thickness of 70 mm has a yield stress of about 462 MPa at most. I can't get it. Further, simply adding a large amount of the alloy element with the aim of increasing the strength will deteriorate the CTOD characteristics.
  • the present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is multilayer welding with a plate thickness of 35 to 100 mm, a yield stress of 460 MPa or more, and a heat input of 100 kJ / cm or less.
  • An object of the present invention is to provide a high-tensile steel sheet having excellent CTOD characteristics in the heat affected zone and to propose an advantageous manufacturing method thereof.
  • the inventors have conducted intensive studies focusing on the influence of the composition of steel on the weld. As a result, the following was found. i) Since the CTOD characteristic is evaluated with a test piece having a full thickness of the steel sheet, the central segregation portion is the starting point of the fracture. Therefore, in order to improve the CTOD characteristics of the weld heat affected zone, the content of elements that easily undergo center segregation, specifically, the contents of C, Mn, P, Ni, and Nb are controlled within an appropriate range, and the hardness of the center segregation zone is increased. It is important to suppress the increase in height.
  • the Ca compound (CaS) added for the purpose of controlling the form of sulfide is crystallized to improve the toughness of the weld heat affected zone. It is effective to use.
  • the present invention developed based on the above findings is C: 0.010 to 0.050 mass%, Si: 0.01 to 0.50 mass%, Mn: 1.80 to 3.50 mass%, P: 0.012 mass%.
  • S 0.0035 mass% or less
  • Al 0.010 to 0.060 mass%
  • Ni 0.1 to 2.0 mass%
  • Cr 1.0 to 3.0 mass%
  • Nb 0.005 to 0.040 mass%
  • Ti 0.005 to 0.025 mass%
  • N 0.0020 to 0.0050 mass%
  • Cr further containing 35Cr + 8Mn ⁇ 63 and 7Cr + 18Mn ⁇ 63, with the balance being a component composition consisting of Fe and inevitable impurities It is a tension steel plate.
  • the high-strength steel sheet of the present invention further includes Cu: less than 1.0 mass%, Mo: 0.05 to 0.50 mass%, V: 0.005 to 0.05 mass%, and B: 0. It is characterized by containing one or more selected from .0005 to 0.0030 mass%, Ca: 0.0005 to 0.0050 mass%, and Mg: 0.0002 to 0.0030 mass%.
  • the O content is 0.0030 mass% or less
  • the Ca, S, and O are represented by the following formula (1): 0 ⁇ Ca ⁇ (0.18 + 130 ⁇ Ca) ⁇ O ⁇ /1.25/S ⁇ 1 (1)
  • each element symbol in the above formula is the content (mass%) of each element. It is characterized by containing.
  • the present invention provides a steel material having any of the above-described component compositions heated to 1030 to 1200 ° C., and then has a cumulative rolling reduction in a temperature range of 950 ° C. or higher of 30% or more and less than 950 ° C.
  • a method for producing a high-strength steel sheet is proposed in which hot rolling is performed at a cumulative rolling reduction of 30 to 70% and then accelerated cooling to 600 ° C. or lower at a cooling rate of 1.0 ° C./s or higher.
  • the method for producing the high-strength steel sheet of the present invention is characterized in that after accelerated cooling to 600 ° C. or lower, tempering is further performed at a temperature of 450 to 650 ° C.
  • heat that is suitable for use in large steel structures such as ships and marine structures, and that is multilayer welded with a heat input of 100 kJ / cm or less even when the plate thickness is 35 to 100 mm and the yield stress is 460 MPa or more. It is possible to stably produce and provide a high-tensile steel sheet that is excellent in low-temperature toughness in the affected area, particularly excellent CTOD characteristics at an extremely low temperature of ⁇ 60 ° C. or lower.
  • C 0.010 to 0.050 mass%
  • C is an element necessary for ensuring the strength of the base material as a high-tensile steel plate.
  • C is less than 0.010 mass%, the hardenability deteriorates. Therefore, in order to ensure the target strength (YS ⁇ 460 MPa), a large amount of a hardenability improving element such as Cu, Ni, Cr, Mo is added. This increases the cost of raw materials and decreases weldability.
  • C exceeds 0.050 mass%, the toughness of the welded portion decreases. Therefore, C is set in the range of 0.010 to 0.050 mass%. Preferably, it is in the range of 0.015 to 0.050 mass%.
  • Si 0.01 to 0.50 mass%
  • Si is an element added as a deoxidizing material and for increasing the strength of the base material, and it is necessary to add 0.01 mass% or more.
  • a large amount of addition exceeding 0.50 mass% causes a decrease in weldability and a decrease in toughness of the welded portion. Therefore, Si is set in the range of 0.01 to 0.50 mass%. Preferably, it is in the range of 0.01 to 0.35 mass%.
  • Mn 1.8 to 3.5 mass% Mn needs to be added in an amount of 1.8 mass% or more in order to ensure the strength of the base material and the weld. However, addition exceeding 3.5 mass% not only lowers weldability but also causes excessive hardenability and lowers the toughness of the base metal and the weld. Therefore, Mn is in the range of 1.8 to 3.5 mass%. The range is preferably 1.8 to 3.3 mass%.
  • P 0.012 mass% or less
  • P is an impurity element that is inevitably mixed in steel, and is also a harmful element that lowers the toughness of the base material and the weld.
  • the upper limit of P is limited to 0.012 mass% in the present invention.
  • it is 0.008 mass% or less.
  • S 0.0035 mass% or less
  • S is an impurity element inevitably mixed in steel, and when contained in excess of 0.0035 mass%, the toughness of the base material and the welded portion is lowered. Therefore, the upper limit of S is set to 0.0035 mass%. Preferably it is 0.0030 mass% or less.
  • Cr 1.0 to 3.0 mass% Cr is an element useful for improving the hardenability of steel and ensuring the strength and toughness of the base material. Moreover, it is a ferrite stabilizing element and has the effect of preventing the excessive stabilization of austenite by Mn and suppressing the formation of island martensite. In order to acquire such an effect, addition of 1.0 mass% or more is required. However, if Cr is added excessively, the hardness of the heat-affected zone increases and the toughness decreases, so the upper limit is made 3.0 mass%. Preferably, it is in the range of 1.0 to 2.8 mass%.
  • sol. Al 0.010 to 0.060 mass%
  • Al is an element added to deoxidize molten steel. It is necessary to contain 0.010 mass% or more with Al. On the other hand, if added in excess of 0.060 mass%, the toughness of the base metal and the welded portion is reduced and mixed with the weld metal by dilution by welding to reduce the toughness, so the upper limit is made 0.060 mass%.
  • sol. The range of Al is 0.017 to 0.055 mass%.
  • Ni 0.1 to 2.0 mass%
  • Ni is an element effective not only for improving the strength and toughness of steel but also for improving the CTOD characteristics of the weld. In order to obtain these effects, it is necessary to add 0.1 mass% or more. However, since Ni is an expensive element and excessive addition causes generation of slab surface flaws during casting, the upper limit is set to 2.0 mass%. Preferably, it is in the range of 0.1 to 1.8 mass%.
  • Nb 0.005 to 0.040 mass%
  • Nb is an element that contributes to the formation of a non-recrystallized region in the low temperature region of austenite.
  • the structure of the base material can be refined and the toughness can be increased.
  • it is effective in improving hardenability and tempering softening resistance, and is also an effective element for improving the base material strength.
  • it is necessary to contain 0.005 mass% or more.
  • the toughness of the weld heat affected zone decreases, so the upper limit is made 0.040 mass%.
  • it is in the range of 0.007 to 0.035 mass%.
  • Ti 0.005 to 0.025 mass% Ti precipitates as TiN when the molten steel is solidified, and suppresses austenite coarsening in the welded portion, thereby contributing to improvement in the toughness of the welded portion.
  • the content is less than 0.005 mass%, the effect is small.
  • TiN is coarsened and the toughness improving effect of the base material and the welded portion cannot be obtained. Therefore, Ti is in the range of 0.005 to 0.025 mass%. Preferably, it is in the range of 0.006 to 0.023 mass%.
  • N 0.0020 to 0.0050 mass%
  • N has an effect of refining crystal grains by combining with Ti or Al to form precipitates and improving the toughness of the base material. It is also an element necessary for forming TiN that suppresses the coarsening of the structure of the heat affected zone. In order to express these effects, N is contained in an amount of 0.0020 mass% or more. However, if added over 0.0050 mass%, the toughness of the base metal and the welded portion is remarkably lowered due to an increase in the solid solution N, and the strength is lowered due to the decrease in the solid solution Nb accompanying the formation of TiNb composite precipitates. Therefore, the upper limit is set to 0.0050 mass%. Preferably, it is in the range of 0.0020 to 0.0047 mass%.
  • 35Cr + 8Mn ⁇ 63 and 7Cr + 18Mn ⁇ 63 Cr is a ferrite stabilizing element, and has an effect of relaxing excessive austenite stabilization by Mn and suppressing generation of island martensite MA in the weld heat affected zone. That is, the addition of Mn alone only enhances the hardenability, but the addition of Cr, which is a ferrite stabilizing element, alleviates excessive austenite stabilization by Mn and suppresses the formation of island martensite. In order to obtain the above effect, it is necessary to add Cr so as to satisfy 35Cr + 8Mn ⁇ 63 and 7Cr + 18Mn ⁇ 63 in relation to Mn. In addition, Preferably 35Cr + 8Mn is 65 or more, and 7Cr + 18Mn is 62 or less.
  • the high-tensile steel sheet of the present invention can further contain one or more selected from Cu, Mo, V, B, Ca, and Mg in the following range in addition to the above component composition.
  • Cu Less than 1.0 mass% Cu is an element effective for increasing the strength of the base material, and it is preferable to add 0.1 mass% or more in order to obtain the above effect. However, since addition of 1.0 mass% or more reduces hot workability, it is preferable to make it less than 1.0 mass%. More preferably, it is 0.7 mass% or less.
  • Mo 0.05 to 0.50 mass% Mo is an element effective for increasing the strength of the base material, and has a particularly large strength improvement effect in a high-tensile steel plate. In order to acquire the said effect, adding 0.05 mass% or more is preferable. However, excessive addition adversely affects toughness, so the upper limit is preferably 0.50 mass%. More preferably, it is in the range of 0.10 to 0.45 mass%.
  • V 0.005 to 0.05 mass%
  • V is an element effective for improving the strength and toughness of the base material, and therefore can be added in an amount of 0.005 mass% or more. However, if it exceeds 0.05 mass%, the toughness is reduced, so when added, it is preferably in the range of 0.005 to 0.05 mass%. More preferably, it is in the range of 0.005 to 0.045 mass%.
  • B 0.0005 to less than 0.0030 mass% B segregates at the austenite grain boundary when cooled from the austenite region, and has the effect of increasing the strength by improving the hardenability. In order to acquire this effect, it is preferable to add 0.0005 mass% or more. However, excessive addition generates a bainite structure containing a large amount of island martensite (MA) in the weld heat-affected zone, and lowers toughness. Therefore, B is preferably added in the range of 0.0005 to 0.0030 mass%. More preferably, it is in the range of 0.0006 to 0.0020 mass%.
  • Ca 0.0005 to 0.0050 mass%
  • Ca combines with S to form CaS, and by fixing S, the form of sulfide is controlled and the toughness is improved. In order to acquire this effect, it is preferable to add 0.0005 mass% or more. However, even if added over 0.0050 mass%, the effect is saturated. Therefore, Ca is preferably added in the range of 0.0005 to 0.0050 mass%. More preferably, it is in the range of 0.0007 to 0.0035 mass%.
  • Mg 0.0002 to 0.0030 mass%
  • Mg is an element that improves toughness by fixing S in the same manner as Ca. In order to acquire this effect, it is preferable to add 0.0002 mass% or more. However, even if added over 0.0030 mass%, the effect is saturated. Therefore, Mg is preferably added in the range of 0.0002 to 0.0030 mass%. More preferably, it is in the range of 0.0003 to 0.0020 mass%.
  • O 0.0030 mass% or less
  • O is an element that lowers the toughness of the base material.
  • the content exceeds 0.0030 mass%, the above-described adverse effect becomes significant, so the upper limit is made 0.0030 mass%. Is preferred. More preferably, it is 0.0025 mass% or less.
  • the above-described Ca, S and O are represented by the following formula (1); 0 ⁇ Ca ⁇ (0.18 + 130 ⁇ Ca) ⁇ O ⁇ /1.25/S ⁇ 1 (1)
  • each element symbol in the above formula is the content (mass%) of each element. It is preferable to contain and satisfy.
  • the center of the above formula (1) ( ⁇ Ca ⁇ (0.18 + 130 ⁇ Ca) ⁇ O ⁇ /1.25/S ⁇ 1) is the atomic concentration of Ca and S effective for sulfide morphology control. This is an index value (also referred to as ACR (Atomic Concentration Ratio)) indicating the ratio of the sulfide, and the form of sulfide can be estimated.
  • CaS which is a sulfide of Ca
  • MnS precipitates on the surface of the crystallized CaS to form a composite sulfide that is difficult to dissolve even at high temperatures.
  • a Mn dilute band is formed around the MnS, the ferrite transformation is further promoted.
  • ACR is 1 or more
  • S is completely fixed by Ca, and MnS acting as a ferrite nuclei does not precipitate on CaS, and fine dispersion of the composite sulfide that becomes a ferrite nuclei cannot be realized.
  • the effect of improving the toughness of the weld heat affected zone cannot be obtained. Therefore, only when the ACR value is greater than 0 and less than 1, MnS is deposited on CaS to form a composite sulfide, which effectively functions as a ferrite nuclei.
  • a more preferable ACR value is in the range of 0.2 to 0.8.
  • the balance other than the above components is Fe and inevitable impurities. However, even if it is other than the said component, if it is in the range which does not injure the effect of this invention, it does not refuse containing.
  • the high-strength steel sheet of the present invention conforms to the present invention in a conventional refining process in which steel is melted in a converter, electric furnace, vacuum melting furnace, etc., and secondary refining such as vacuum degassing is performed as necessary.
  • the molten steel adjusted to the component composition is continuously cast into a steel material (slab)
  • the slab is reheated and hot-rolled to a desired plate thickness, accelerated cooling, or after the accelerated cooling
  • the steel sheet can be manufactured through a process of further tempering, and there is no difference from a conventional manufacturing method of a high-strength steel sheet.
  • the steel plate temperature is the temperature at the center of the plate thickness.
  • the temperature at the central portion of the plate thickness can be obtained by calculation using a difference method or the like from the plate thickness, surface temperature, cooling conditions, and the like.
  • Slab reheating temperature 1030-1200 ° C
  • the slab reheating temperature before the hot rolling needs to be 1030 ° C. or higher in order to surely press-bond the casting defects existing inside the slab by hot rolling.
  • the upper limit of the heating temperature is 1200 ° C.
  • the range is preferably from 1030 to 1170 ° C.
  • the rate needs to be 30% or more. If it is less than 30%, abnormal coarse grains generated during reheating of the slab remain, which adversely affects the toughness of the base material. Preferably it is 35% or more.
  • the upper limit of the cumulative rolling reduction at this stage is not particularly limited as long as the rolling reduction in a temperature range of less than 950 ° C. can be secured.
  • the end temperature of hot rolling is preferably in the range of 650 to 850 ° C.
  • the temperature is lower than 650 ° C.
  • the processed ferrite remains and the toughness is lowered.
  • the temperature exceeds 850 ° C. the structure becomes coarse and the toughness is lowered. More preferably, it is in the range of 680 to 820 ° C.
  • Cooling rate to 600 ° C. or lower After completion of the hot rolling, it is important to accelerate cooling to a temperature of 600 ° C. or lower at a cooling rate of 1.0 ° C./s or higher.
  • the cooling rate is less than 1.0 ° C./s, it is not possible to suppress the formation of ferrite having low strength, and thus sufficient strength of the base material cannot be obtained.
  • it is 1.2 degrees C / s or more.
  • 30 degrees C / s or less is preferable from a viewpoint of ensuring the toughness of a base material.
  • the reason for setting the temperature at which the cooling is stopped to 600 ° C. is that if the temperature is higher than 600 ° C., the fraction of the structure such as ferrite + pearlite and upper bainite becomes high, and high strength and high toughness are not compatible. is there.
  • the stop temperature for accelerated cooling is preferably 350 ° C. or higher from the viewpoint of suppressing the generation of a hard phase having poor toughness such as island martensite.
  • Tempering temperature 450-650 ° C
  • the center thickness of the steel sheet is preferably in the range of 450 to 650 ° C. If it is less than 450 degreeC, the effect of sufficient tempering is not acquired.
  • tempering at a temperature exceeding 650 ° C. is not preferable because carbonitrides are coarsely precipitated and the toughness is lowered or the strength is lowered. More preferably, it is in the range of 480 to 620 ° C.
  • the tempering time is preferably in the range of 10 to 300 min.
  • the high-tensile steel sheet of the present invention suppresses the coarsening of austenite grains in the weld heat affected zone, and further finely disperses ferrite transformation nuclei that do not dissolve even at high temperatures, so that the weld heat affected zone
  • high toughness is obtained even in the heat affected zone.
  • the structure of the weld heat-affected zone is refined by the first welding, so only the toughness of the untransformed region is improved.
  • the retransformed austenite grains can also be made finer, a reduction in toughness due to heat input during welding can be greatly reduced.
  • the steels of AX with the various composition shown in Table 1 are melted and made into a steel material (slab) by continuous casting method, then hot rolled under various conditions shown in Table 2 and accelerated cooling Or a tempering treatment to obtain a thick steel plate No. 50 to 100 mm thick. 1-30 were produced. Subsequently, the said thick steel plate was used for the following evaluation tests. ⁇ Evaluation of base material> ⁇ Strength characteristics JIS No. 4 test piece having a length direction perpendicular to the rolling direction of the steel sheet was taken from the position of 1/2 the thickness of the thick steel sheet, and the yield stress YS and the tensile strength TS were measured.
  • a weld joint was prepared in the same manner as described above, and a CTOD test piece having a straight-side weld bond portion as a notch position of a three-point bending CTOD test piece was collected, and a CTOD value at -60 ° C ( ⁇ -60 ° C) ) was measured.
  • the above test was performed three times under each condition, and those having a minimum CTOD value ( ⁇ 60 ° C.) of 0.50 mm or more were evaluated as having good CTOD characteristics of the welded joint.
  • the high-tensile steel plate of the present invention can be applied to civil engineering / architectural fields such as buildings and bridges, as well as steel structures such as ships, offshore structures, pressure vessels, and penstocks.

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  • Heat Treatment Of Steel (AREA)

Abstract

Après le réchauffement à 1030-1200°C d'un matériau d'acier, qui contient 0,010-0,050 % de C, 0,01-0,50 % de Si, 1,80-3,50 % de Mn, 0,012 % ou moins de P, 0,0035 % ou moins de S, 0,010-0,060 % de sol. Al, 0,1-2,0 % de Ni, 1,0-3,0 % de Cr, 0,005 à 0,040 % de Nb, 0,005 à 0,025 % de Ti et 0,0020 à 0,0050 % de N, en % en masse, et qui satisfait à 35 Cr +8 Mn ≥ 63 et 7 Cr+18 Mn ≤ 63, le laminage à chaud est effectué à une réduction cumulée de 30 % ou plus à 950°C ou plus et à une réduction cumulée de 30-70 % en-dessous de 950°C et un refroidissement accéléré jusqu'à 600°C ou moins est effectué à 1,0°C/s ou plus, ce qui permet d'obtenir une tôle d'acier à haute résistance à la traction, qui présente une épaisseur de tôle de 35-100 mm et une limite d'élasticité de 460 MPa ou plus et qui présente d'excellentes caractéristiques de CTOD de la zone affectée thermiquement dans laquelle un soudage en plusieurs passes a été effectué.
PCT/JP2015/080154 2014-10-28 2015-10-27 Tôle d'acier à haute résistance à la traction, présentant une excellente résilience aux basses températures de zones de soudage affectées thermiquement, et son procédé de production Ceased WO2016068094A1 (fr)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016164289A (ja) * 2015-03-06 2016-09-08 新日鐵住金株式会社 溶接用高張力鋼
JP2017002349A (ja) * 2015-06-09 2017-01-05 Ｊｆｅスチール株式会社 高張力鋼板およびその製造方法

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000256777A (ja) * 1999-03-08 2000-09-19 Nippon Steel Corp 強度および低温靱性に優れた高張力鋼板
JP2004323917A (ja) * 2003-04-25 2004-11-18 Kobe Steel Ltd 高強度高靭性鋼板
JP2009024228A (ja) * 2007-07-20 2009-02-05 Nippon Steel Corp 高温強度と低温靭性に優れる溶接構造用鋼の製造方法
WO2010082361A1 (fr) * 2009-01-15 2010-07-22 新日本製鐵株式会社 Acier pour construction soudée ayant une excellente résistance à température élevée et une excellente résilience aux basses températures et procédés de production de l'acier
JP2010229453A (ja) * 2009-03-26 2010-10-14 Jfe Steel Corp １層大入熱溶接熱影響部の靭性に優れた高強度厚鋼板およびその製造方法
JP2011246768A (ja) * 2010-05-27 2011-12-08 Kobe Steel Ltd 高張力鋼板およびその製造方法
JP2013019015A (ja) * 2011-07-11 2013-01-31 Jfe Steel Corp 溶接熱影響部の靭性に優れた鋼板
JP2013095926A (ja) * 2011-10-28 2013-05-20 Nippon Steel & Sumitomo Metal Corp 溶接性に優れた高張力鋼板およびその製造方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101634001B (zh) * 2008-07-24 2011-07-20 宝山钢铁股份有限公司 一种ct90级连续油管用钢及其制造方法
JP5509945B2 (ja) * 2010-03-12 2014-06-04 Ｊｆｅスチール株式会社 溶接熱影響部の靭性に優れた鋼板
JP5699798B2 (ja) * 2011-05-18 2015-04-15 Ｊｆｅスチール株式会社 大入熱溶接熱影響部の靭性に優れた低降伏比高張力鋼材およびその製造方法
CN103320719B (zh) * 2013-06-19 2015-05-20 宝山钢铁股份有限公司 低成本可大热输入焊接高强韧性钢板及其制造方法
CN103422025B (zh) * 2013-09-13 2015-10-14 武汉钢铁(集团)公司 屈服强度≥690MPa的低屈强比结构用钢及其生产方法

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000256777A (ja) * 1999-03-08 2000-09-19 Nippon Steel Corp 強度および低温靱性に優れた高張力鋼板
JP2004323917A (ja) * 2003-04-25 2004-11-18 Kobe Steel Ltd 高強度高靭性鋼板
JP2009024228A (ja) * 2007-07-20 2009-02-05 Nippon Steel Corp 高温強度と低温靭性に優れる溶接構造用鋼の製造方法
WO2010082361A1 (fr) * 2009-01-15 2010-07-22 新日本製鐵株式会社 Acier pour construction soudée ayant une excellente résistance à température élevée et une excellente résilience aux basses températures et procédés de production de l'acier
JP2010229453A (ja) * 2009-03-26 2010-10-14 Jfe Steel Corp １層大入熱溶接熱影響部の靭性に優れた高強度厚鋼板およびその製造方法
JP2011246768A (ja) * 2010-05-27 2011-12-08 Kobe Steel Ltd 高張力鋼板およびその製造方法
JP2013019015A (ja) * 2011-07-11 2013-01-31 Jfe Steel Corp 溶接熱影響部の靭性に優れた鋼板
JP2013095926A (ja) * 2011-10-28 2013-05-20 Nippon Steel & Sumitomo Metal Corp 溶接性に優れた高張力鋼板およびその製造方法

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016164289A (ja) * 2015-03-06 2016-09-08 新日鐵住金株式会社 溶接用高張力鋼
JP2017002349A (ja) * 2015-06-09 2017-01-05 Ｊｆｅスチール株式会社 高張力鋼板およびその製造方法

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