EP1659191A1 - Tole d'acier lamine a froid a haute resistance a la traction et son procede de production - Google Patents

Tole d'acier lamine a froid a haute resistance a la traction et son procede de production Download PDF

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Publication number
EP1659191A1
EP1659191A1 EP04772121A EP04772121A EP1659191A1 EP 1659191 A1 EP1659191 A1 EP 1659191A1 EP 04772121 A EP04772121 A EP 04772121A EP 04772121 A EP04772121 A EP 04772121A EP 1659191 A1 EP1659191 A1 EP 1659191A1
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steel sheet
cold
martensite
mass
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German (de)
English (en)
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EP1659191A4 (fr
EP1659191B1 (fr
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Shusaku JFE Steel Corporation TAKAGI
Tetsuo JFE Steel Corporation SHIMIZU
Naoki JFE Steel Corporation NISHIYAMA
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JFE Steel Corp
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JFE Steel Corp
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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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
    • C21D8/0436—Cold rolling
    • 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
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
    • C21D8/0473—Final recrystallisation annealing
    • 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
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite
    • 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
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0236—Cold rolling

Definitions

  • the present invention relates to a high tensile cold-rolled steel sheet having 590 MPa or higher tensile strength suitable for the reinforcing members of pillar and dashboard of automobile, and the like, specifically to a high tensile cold-rolled steel sheet having a good strength-elongation balance, and showing excellent crashworthiness at about 10 s -1 of strain rate, and to a method for manufacturing thereof.
  • JP-A-61-217529 discloses a high tensile cold-rolled steel sheet having significantly improved elongation by adopting a microstructure containing 10% or more of retained austenite. This high tensile cold-rolled steel sheet, however, is not studied in terms of crashworthiness.
  • JP-A-11-61327 discloses a high tensile cold-rolled steel sheet having a microstructure which is controlled to have 3 to 30% of area percentage of martensite and 5 ⁇ m or smaller average region size of martensite, and having 0.13 or larger work-hardening exponent (n value), 75% or smaller yield ratio, 18000 MPa•% or larger strength-elongation balance, and 1.2 or larger hole-expansion ratio.
  • n value work-hardening exponent
  • the crashworthiness of the high tensile cold-rolled steel sheet is evaluated by the n value.
  • n value observed in the disclosed patent is determined by a static tensile test (the strain rate per JIS is approximately in a range from 10 -3 to 10 -2 s -1 ). Since a car-crash generates 10 to 10 3 s -1 of strain rate in a reinforcing member, the n value derived from the static tensile test cannot fully evaluate the crashworthiness. To this point, the high tensile cold-rolled steel sheet was re-evaluated taking into account the strain rate on crashing, which is described later, and there was confirmed that satisfactory crashworthiness cannot be attained.
  • Japanese Patent No. 3253880 discloses a method for manufacturing high tensile cold-rolled steel sheet having a microstructure structured by ferrite and martensite, and having excellent press-forming property and crashworthiness.
  • the crashworthiness of the high tensile cold-rolled steel sheet is evaluated by the absorbed energy at 2000 s -1 of strain rate.
  • the absorbed energy which is determined by that strain rate level is the energy necessary to absorb actually the energy on car-crash by the deformation of the reinforcing member.
  • JP-A-10-147838 discloses a high tensile cold-rolled steel sheet which improves the crashworthiness by controlling the area percentage of martensite and the ratio of the hardness of martensite to the hardness of ferrite.
  • the hardness of martensite and of ferrite is determined by a Vickers hardness gauge.
  • Table 4 on page 189 of "Proceedings of the International Workshop on the innovative Structural Materials for Infrastructure in 21 st Century" [T. Ohmura et al.; "ULTRA-STEEL 2000” , National Research Institute for Metals (2000)]
  • the correct hardness of martensite cannot be evaluated by Vickers hardness gauge because the hardness of martensite has a dependency on the size of indentation. According to an investigation given by the inventors of the present invention, no correlation was found between the crashworthiness and the Vickers hardness.
  • the disclosed patent evaluates the crashworthiness by the absorbed energy at 800 s -1 of strain rate.
  • static-dynamic ratio is the ratio of the strength determined by a dynamic tensile test at strain rates from 10 2 to 10 3 s -1 to the strength determined by a static tensile test at strain rates from 10 -3 to 10 -2 s -1 . Larger ratio means larger strength and larger absorbed energy on crash.
  • An object of the present invention is to provide a high tensile cold-rolled steel sheet having a good strength-elongation balance (TS*EL) and attaining excellent crashworthiness at about 10 s -1 of strain rate, and to provide a method for manufacturing thereof.
  • TS*EL good strength-elongation balance
  • the characteristics targeted in the present invention are the following.
  • a high tensile cold-rolled steel sheet consisting essentially of 0.04 to 0.13% C, 0.3 to 1.2% Si, 1.0 to 3.5% Mn, 0.04% or less P, 0.01% or less S, 0.07% or less Al, by mass, and balance of Fe and inevitable impurities; having a microstructure containing 50% or larger area percentage of ferrite and 10% or larger area percentage of martensite, and having 0.85 to 1.5 of ratio of intervals of the martensite in the rolling direction to those in the sheet thickness direction; and having 8 GPa or larger nano strength of the martensite.
  • the high tensile cold-rolled steel sheet can be manufactured by a method having the steps of: hot-rolling a steel slab having the above composition, into a steel sheet, followed by coiling the steel sheet at coiling temperatures ranging from 450°C to 650°C; cold-rolling the coiled steel sheet at cold-rolling reductions ranging from 30 to 70%; annealing the cold-rolled steel sheet by heating to a temperature region of [the coiling temperature + the cold-rolling reduction percentage x 4.5] - [the coiling temperature + the cold-rolling reduction percentage x 5.5] (°C) ; and cooling the annealed steel sheet to temperatures of 340°C or below at average cooling rates of 10°C/s or more.
  • the inventors of the present invention applied the sensing block type impact tensile tester to investigate the absorbed energy of high tensile cold-rolled steel sheet at strain rates around 10 s -1 , and derived the following findings.
  • the C content is required to be 0.04% by mass or more to control the tensile strength appropriately and to assure the area percentage of martensite to 10% or larger. If, however, the C content exceeds 0.13% by mass, the weldability significantly deteriorates. Accordingly, the C content is specified to a range from 0.04 to 0.13% by mass, and preferably from 0.07 to 0.12% by mass.
  • Silicon is an important element to control the dispersed state of martensite and to control the nano hardness of the martensite.
  • the Si content is required to be 0.3% by mass or more. If, however, the Si content exceeds 1.2% by mass, the effect saturates, and the chemical conversion treatment performance significantly deteriorates. Consequently, the Si content is specified to a range from 0.3 to 1.2% by mass, and preferably from 0.4 to 0.7% by mass.
  • the Mn content is required to be 1.0% by mass or more to assure 590 MPa or higher tensile strength. Manganese is extremely effective to increase the nano hardness of martensite. If, however, the Mn content exceeds 3.5% by mass, the strength significantly increases, and the elongation largely decreases. Therefore, the Mn content is specified to a range from 1.0 to 3.5% by mass, and preferably from 2.3 to 2.8% by mass.
  • the P content is specified to 0.04% by mass or less, and preferably 0.02% by mass or less. Smaller P content is more preferable.
  • the S content is specified to 0.01% by mass or less, and preferably 0.006% by mass or less. Smaller S content is more preferable.
  • the Al content is preferably adjusted to 0.001% by mass or more. If, however, the Al content exceeds 0.07% by mass, a large amount of inclusions appears to cause flaws on the cold-rolled steel sheet. Therefore, the Al content is specified to 0.07% by mass or less, and preferably 0.05% by mass or less.
  • the inevitable impurities are N, O, Cu, and the like. Since N enhances aging and deteriorates elongation properties, the N content is preferably limited to 0.005% by mass or less.
  • addition of at least one element selected from the group consisting of 0.5% or less Cr, 0.3% or less Mo, 0.5% or less Ni, and 0.002% or less B, by mass is effective to improve the quenchability and to control the amount of martensite.
  • Chromium is preferably added by an amount of 0.02% by mass or more to improve the quenchability and to control the amount of martensite.
  • the Cr content exceeding 0.5% by mass deteriorates the performance of electrodeposition coating which is given to the press-formed parts. Accordingly, the Cr content is specified to 0.5% by mass or less, and preferably 0.2% by mass or less.
  • Molybdenum is preferably added by an amount of 0.05% by mass or more to improve the quenchability and to control the amount of martensite. If, however, the Mo content exceeds 0.3% by mass, the cold-rolling performance deteriorates. Consequently, the Mo content is specified to 0.3% by mass or less, and preferably 0.2% by mass or less.
  • Nickel is preferably added by an amount of 0.05% by mass or more to improve the quenchability and to control the amount of martensite. If, however, the Ni content exceeds 0.5% by mass, the cold-rolling performance deteriorates. Consequently, the Ni content is specified to 0.5% by mass or less, and preferably 0.3% by mass or less.
  • Boron is preferably added by the amount of 0.0005% by mass or more to improve the quenchability and to control the amount of martensite. If, however, the B content exceeds 0.002% by mass, the cold-rolling performance deteriorates. Consequently, the B content is specified to 0.002% by mass or less, and preferably 0.001% by mass or less.
  • the addition of at least one element selected from the group consisting of 0.05% or less Ti and 0.05% or less Nb, by mass, is more effective in improving the quenchability, refining the ferrite, and controlling the dispersion of martensite.
  • Titanium is preferably added by an amount of 0.005% by mass or more to refine the ferrite grains and thus to control the dispersion of martensite. If, however, the Ti content exceeds 0.05% by mass, the effect saturates. Therefore, the Ti content is specified to 0.05% by mass or less, and preferably from 0.005 to 0.02% by mass or less.
  • the Nb content is specified to 0.05% by mass or less, and preferably from 0.005 to 0.02% by mass.
  • the area percentage of ferrite is required to be adjusted to 50% or larger. If the area percentage of the ferrite is smaller than 50%, the amount of hard phase other than the ferrite becomes large, which results in excess strength to deteriorate the strength-elongation balance. At strain rates around 10 s -1 , since the increase in the stress during deformation of ferrite is large, if the area percentage of ferrite is small, the absorbed energy cannot be increased. Accordingly, the area percentage of ferrite is preferably in a range from 60 to 80%.
  • the area percentage of martensite is required to be adjusted to 10% or more. If the area percentage of martensite is smaller than 10%, satisfactory crashworthiness cannot be attained.
  • the area percentage of martensite is preferably in a range from 20 to 40%.
  • austenite is preferably less as far as possible, and 10% or smaller area percentage thereof is preferred.
  • the area percentage of austenite is preferably adjusted to smaller than 3%.
  • the determination of area percentage of ferrite, martensite, and other phases was conducted by: mirror-polishing the sheet-thickness cross section in the rolling direction of the steel sheet; etching the polished surface using a 1.5% nital; observing the etched surface using a scanning electron microscope (SEM) at a position of 1/4 sheet thickness to prepare photographs (at x1000 magnification); and then processing the photographs by an image-analyzer.
  • SEM scanning electron microscope
  • the ratio of intervals of the martensite in the rolling direction to that in the sheet thickness direction (the ratio of intervals of martensite), is required to be adjusted to a range from 0.85 to 1.5. If the ratio becomes smaller than 0.85 or larger than 1.5, sufficient elongation and crashworthiness cannot be attained.
  • the dislocation preferentially moves through a region free from martensite.
  • the ratio of intervals of martensite exceeds 1.5, that is, when the intervals of phases in the rolling direction widens larger than the intervals of phases in the sheet thickness direction, or when the ratio of intervals of martensite becomes smaller than 0.85, that is, when the intervals of phases in the sheet thickness direction becomes wider than those in the rolling direction, the dislocation moves through a region of wide intervals of phases, or through a region without the martensite. As a result, sufficient elongation and crashworthiness cannot be attained.
  • the ratio of intervals of martensite is between 0.85 and 1.5, and is close to 1, that is, when there is not much difference between the intervals of phases in the sheet thickness direction and those in the rolling direction, the migration of dislocation is suppressed by the martensite, which increases the amount of accumulated dislocation to increase the deformation stress, thereby improving the crashworthiness.
  • the elongation also increases because the distribution of martensite becomes relatively uniform.
  • the ratio of intervals of martensite is preferably in a range from 1.0 to 1.3.
  • the ratio of intervals of martensite in the sheet width direction to those in the sheet thickness direction tends to become close to 1 compared with the ratio of intervals of the phases in the rolling direction to those in the sheet thickness direction. According to the present invention, therefore, the direction which maximizes the intervals of martensite is represented by the rolling direction, and the degree of dispersion of martensite is evaluated by the ratio of intervals of phases in the rolling direction to those in the sheet thickness direction.
  • the ratio of intervals of martensite was determined as follows.
  • the average intervals of martensite in the rolling direction are (a 1 + a 2 + a 3 + a 4 + a 5 )/5, while those in the sheet thickness direction are (b 1 + b 2 + b 3 )/3.
  • the ratio of intervals of martensite is expressed by ⁇ ( a 1 + a 2 + a 3 + a 4 + a 5 ) / 5 ⁇ / ⁇ ( b 1 + b 2 + b 3 ) / 3 ⁇ .
  • the nano hardness of martensite is further requested to be adjusted to 8 GPa or more.
  • the strength-elongation balance and the crashworthiness deteriorate.
  • a presumable reason of the deterioration is that, when the nano hardness of martensite is small and when the deformation stress of martensite is small, the effect of the martensite to suppress the migration of dislocation becomes weak. Larger nano hardness of martensite is more preferable, and 10 GPa or larger nano hardness thereof is preferable.
  • the nano hardness of martensite is the hardness determined by the following procedure.
  • a steel slab was prepared by casting the molten steel by a known method such as continuous casting process. Then, the steel slab was heated, followed by hot-rolling by a known method to obtain a steel sheet.
  • the hot-rolled steel sheet is required to be coiled at coiling temperatures ranging from 450°C to 650°C. If the coiling temperature is below 450°C, the strength of steel sheet increases to increase the possibility of fracture thereof during cold-rolling. If the coiling temperature exceeds 650°C, the banded structure significantly develops and remains even after cold-rolling and annealing, which fails to control the ratio of intervals of martensite within a desired range.
  • the coiling temperature is preferably in a range from 500°C to 650°C.
  • the coiled steel sheet is required to be cold-rolled at cold-rolling reductions ranging from 30 to 70%. If the cold-rolling reduction is smaller than 30%, the structure becomes coarse, and the target ratio of intervals of martensite becomes smaller than 0.85, thereby deteriorating both the elongation and the crashworthiness. If the cold-rolling reduction exceeds 70%, banded structure is formed after annealing, and the ratio of intervals of martensite exceeds 1.5.
  • the annealing needs to be given at elevated temperatures to avoid the formation of band structure.
  • the heating temperature during annealing is required to be varied depending on the coiling temperature and the cold-rolling reduction, or to be required to enter a temperature region of [the coiling temperature + the cold-rolling reduction percentage x 4.5] - [the coiling temperature + the cold-rolling reduction percentage x 5.5] (°C).
  • the heating temperature is below [the coiling temperature + the cold-rolling reduction percentage x 4.5], the banded structure cannot be diminished, the desired ratio of intervals of martensite cannot be attained, and further the diffusion of substitution elements such as Si and Mn becomes insufficient, thereby failing in attaining 8 GPa or larger nano hardness of martensite.
  • the heating temperature exceeds [the coiling temperature + the cold-rolling reduction percentage x 5.5] (°C) (°C)
  • the austenite diffuses nonuniformly during heating, which fails to attain the desired ratio of intervals of martensite.
  • the nano hardness of martensite cannot be increased to 8 GPa or larger, thus deteriorating the elongation and the crashworthiness presumably because the austenite become coarse and the martensitic block size after annealing becomes coarse.
  • the holding time during heating is preferably 30 seconds or more because less than 30 seconds of heating may formmartsite at 10% or larger area percentages after annealing and may raise difficulty in attaining stable characteristics over the whole length of the coil. If, however, the holding time exceeds 60 seconds, the effect saturates, and the manufacturing cost increases. Therefore, the holding time is preferably not more than 60 seconds.
  • the annealed steel sheet is required to be cooled to 340°C or below at cooling rates of 10°C/sec or higher. If the cooling rate is lower than 10°C/sec, or if the cooling-stop temperature exceeds 340°C, the desired nano hardness of martensite cannot be attained.
  • the cooling rate referred to herein is the average cooling rate between the lower limit temperature of the above heating temperatures, or [the coiling temperature + the cold-rolling reduction percentage x 4.5] (°C), and the temperature to cool at cooling rates of 10°C/sec or higher.
  • the cooling rate is preferably adjusted to 50°C/sec or smaller.
  • the temperature for cooling at that cooling rate is preferably adjusted to 300°C or below, and 270°C or below is more preferable.
  • the treatment after the cooling at that cooling rate is not specifically limited.
  • cooling to room temperature may be given by a known method such as air-cooling (allowing standing) and slow-cooling.
  • the reheating after the cooling should be avoided because the reheating tempers to soften the martensite.
  • the annealing is advantageously conducted in a continuous annealing furnace.
  • the 30 seconds or longer holding time in the continuous annealing process can be attained by selecting the annealing temperature (ultimate highest temperature in the continuous annealing) to a temperature in the above heating temperature region, and by holding the steel within the temperature region for 30 seconds or more.
  • the soaking time (or called the "annealing time") at the annealing temperature may be selected to 30 seconds or more, or, after reaching the annealing temperature, the steel may be slowly cooled to the lower limit of the above heating temperature region, while adjusting the retention time in the heating temperature region to 30 seconds or more.
  • the Ac3 transformation point given in Table 1-1 and Table 1-2 was determined by preparing samples from the respective sheet bars after hot-rough-rolling, using Thermec Master Z of Fuji Electronics Industrial Co., Ltd.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
EP04772121.2A 2003-08-26 2004-08-18 Tole d'acier lamine a froid a haute resistance a la traction et son procede de production Expired - Lifetime EP1659191B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2003301473 2003-08-26
JP2004208834 2004-07-15
PCT/JP2004/012160 WO2005019487A1 (fr) 2003-08-26 2004-08-18 Tole d'acier lamine a froid a haute resistance a la traction et son procede de production

Publications (3)

Publication Number Publication Date
EP1659191A1 true EP1659191A1 (fr) 2006-05-24
EP1659191A4 EP1659191A4 (fr) 2012-02-29
EP1659191B1 EP1659191B1 (fr) 2014-07-30

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US (1) US20060231176A1 (fr)
EP (1) EP1659191B1 (fr)
KR (1) KR20060032139A (fr)
CA (1) CA2522607C (fr)
WO (1) WO2005019487A1 (fr)

Cited By (4)

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EP2128288A1 (fr) * 2007-01-31 2009-12-02 JFE Steel Corporation Produits d'acier à haute résistance à la traction, présentant une excellente résistance à la fracture retardée et leur procédé de fabrication
DE102012013113A1 (de) * 2012-06-22 2013-12-24 Salzgitter Flachstahl Gmbh Hochfester Mehrphasenstahl und Verfahren zur Herstellung eines Bandes aus diesem Stahl mit einer Mindestzugfestigkleit von 580MPa
EP2781615A1 (fr) * 2011-11-15 2014-09-24 JFE Steel Corporation Tôle d'acier mince et procédé de production de cette dernière
EP2562272A3 (fr) * 2011-08-26 2017-07-26 Rautaruukki Oyj Méthode pour la production d'un produit d'acier avec des propriétés mécaniques excellentes, le produit fabriqué par ladite méthode et l'utilisation des produits

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KR101009839B1 (ko) * 2008-06-26 2011-01-19 현대제철 주식회사 고강도 고성형 강판의 제조방법
KR100958019B1 (ko) * 2009-08-31 2010-05-17 현대하이스코 주식회사 복합조직강판 및 이를 제조하는 방법
KR101410435B1 (ko) * 2010-03-31 2014-06-20 신닛테츠스미킨 카부시키카이샤 성형성이 우수한 고강도 용융 아연 도금 강판 및 그 제조 방법
KR101435251B1 (ko) * 2012-03-29 2014-08-28 현대제철 주식회사 냉연강판 제조 방법
CN107190209A (zh) * 2017-04-27 2017-09-22 甘肃酒钢集团宏兴钢铁股份有限公司 低屈强比高强度热轧钢板及其生产方法
CN107190208A (zh) * 2017-04-27 2017-09-22 甘肃酒钢集团宏兴钢铁股份有限公司 高延伸率高强度冷轧钢板及其生产方法
KR102638472B1 (ko) * 2019-04-11 2024-02-21 닛폰세이테츠 가부시키가이샤 강판 및 그 제조 방법

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EP2128288A1 (fr) * 2007-01-31 2009-12-02 JFE Steel Corporation Produits d'acier à haute résistance à la traction, présentant une excellente résistance à la fracture retardée et leur procédé de fabrication
EP2128288A4 (fr) * 2007-01-31 2010-03-10 Jfe Steel Corp Produits d'acier à haute résistance à la traction, présentant une excellente résistance à la fracture retardée et leur procédé de fabrication
US8357252B2 (en) 2007-01-31 2013-01-22 Jfe Steel Corporation High tensile strength steel having favorable delayed fracture resistance and method for manufacturing the same
EP2562272A3 (fr) * 2011-08-26 2017-07-26 Rautaruukki Oyj Méthode pour la production d'un produit d'acier avec des propriétés mécaniques excellentes, le produit fabriqué par ladite méthode et l'utilisation des produits
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EP2781615A4 (fr) * 2011-11-15 2015-07-01 Jfe Steel Corp Tôle d'acier mince et procédé de production de cette dernière
DE102012013113A1 (de) * 2012-06-22 2013-12-24 Salzgitter Flachstahl Gmbh Hochfester Mehrphasenstahl und Verfahren zur Herstellung eines Bandes aus diesem Stahl mit einer Mindestzugfestigkleit von 580MPa

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KR20060032139A (ko) 2006-04-14
WO2005019487A1 (fr) 2005-03-03
CA2522607A1 (fr) 2005-03-03
US20060231176A1 (en) 2006-10-19
EP1659191A4 (fr) 2012-02-29
EP1659191B1 (fr) 2014-07-30

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