摘要:
A steel is subjected to a hot rolling step, a cold rolling step, and an annealing step having a maximum achieving temperature: 800° C. to 900° C., two-step heating, and two-step cooling. The two-step heating includes first-step heating to (maximum achieving temperature—(10° C. to 50° C.)) at an average temperature raising rate: 0.5° C. to 5.0° C./s and second-step heating in which the temperature raising time from that temperature range to the maximum achieving temperature is specified to be 30 to 150 s. Two-step cooling includes first-step cooling to cool from the maximum achieving temperature at a cooling rate of 10° C. to 40° C./s and second-step cooling to cool to a temperature range of 400° C. to 500° C. at a cooling rate of 0.2 to 0.8 times the first-step cooling rate for a cooling time of 0.2 to 0.8 times the total cooling time.
摘要:
A thin high strength steel sheet having excellent formability has a composition which includes, by mass %, 0.08 to 0.15% of C, 0.5 to 1.5% of Si, 0.5 to 1.5% of Mn, 0.01 to 0.1% of Al, and 0.005% or less of N to form a hot rolled sheet is conducted.
摘要:
A high strength hot-rolled steel sheet with a tensile strength of not less than 590 MPa which exhibits excellent bake hardenability and stretch-flangeability has a chemical composition including, in terms of mass %, C at 0.040 to 0.10%, Si at not more than 0.3%, Mn at 1.7 to 2.5%, P at not more than 0.030%, S at not more than 0.005%, Al at not more than 0.1% and N at 0.006 to 0.025%, and microstructure wherein a bainite phase represents not less than 60%, the total of a ferrite phase and a pearlite phase represents not more than 10%, and the bainite phase includes grains among which cementite grains have been precipitated at not less than 1.4×104 grains/mm2 and the cementite grains have an average grain diameter of not more than 1.5 μm.
摘要翻译:具有优异的烘烤淬透性和拉伸凸缘性的抗拉强度不低于590MPa的高强度热轧钢板具有以质量%计含有0.040〜0.10%的C的化学组成,不超过Si 不超过0.3%,Mn为1.7〜2.5%,P为0.030%以下,S为0.005%以下,Al为0.1%以下,N为0.006〜0.025%,其中贝氏体相为不 小于60%,铁素体相和珠光体相的总和为10%以下,贝氏体相为含有不少于1.4×104个/ mm 2的渗碳体粒子的晶粒,渗碳体为 平均粒径不超过1.5μm。
摘要:
A slab has a steel composition including 0.020% to 0.065% of C, 0.1% or less of Si, 0.40% to less than 0.80% of Mn, 0.030% or less of P, 0.005% or less of S, 0.08% to 0.16% of Ti, 0.005% to 0.1% of Al, 0.005% or less of N, and the balance being Fe and incidental impurities, in which Ti*(=Ti−(48/14)×N) satisfies [Ti*≧0.08] and [0.300≦C/Ti*≦0.375], is subjected to hot rolling to obtain a hot-rolled steel sheet in which the steel microstructure includes, in terms of area fraction, 95% or more of a ferrite phase; the average ferrite grain size is 10 μm or less; the average grain size of Ti carbides precipitated in steel is 10 nm or less; and Ti in the amount of 80% or more of Ti* is precipitated as Ti carbides.
摘要翻译:钢坯的组成为:C:0.020〜0.065%,Si:0.1%以下,Si:0.40%〜0.80%,P:0.030%以下,S:0.005%以下,S:0.08〜0.16 Ti = 0.005%〜0.1%,N为0.005%以下,余量为Ti *(= Ti-(48/14)×N)为Fe [Ti *≥0.08] ]和[0.300≦̸ C / Ti *≦̸ 0.375]进行热轧,得到其中钢组织包含面积率为95%以上的铁素体相的热轧钢板; 平均铁素体晶粒尺寸为10μm以下; 钢中析出的Ti碳化物的平均粒径为10nm以下; Ti的含量为80%以上的Ti作为Ti碳化物析出。
摘要:
A slab has a steel composition including 0.020% to 0.065% of C, 0.1% or less of Si, 0.40% to less than 0.80% of Mn, 0.030% or less of P, 0.005% or less of S, 0.08% to 0.16% of Ti, 0.005% to 0.1% of Al, 0.005% or less of N, and the balance being Fe and incidental impurities, in which Ti*(=Ti−(48/14)×N) satisfies [Ti*≧0.08] and [0.300≦C/Ti*≦0.375], is subjected to hot rolling to obtain a hot-rolled steel sheet in which the steel microstructure includes, in terms of area fraction, 95% or more of a ferrite phase; the average ferrite grain size is 10 μm or less; the average grain size of Ti carbides precipitated in steel is 10 nm or less; and Ti in the amount of 80% or more of Ti* is precipitated as Ti carbides.
摘要:
A high strength hot-rolled steel sheet with a tensile strength of not less than 590 MPa which exhibits excellent bake hardenability and stretch-flangeability has a chemical composition including, in terms of mass %, C at 0.040 to 0.10%, Si at not more than 0.3%, Mn at 1.7 to 2.5%, P at not more than 0.030%, S at not more than 0.005%, Al at not more than 0.1% and N at 0.006 to 0.025%, and microstructure wherein a bainite phase represents not less than 60%, the total of a ferrite phase and a pearlite phase represents not more than 10%, and the bainite phase includes grains among which cementite grains have been precipitated at not less than 1.4×104 grains/mm2 and the cementite grains have an average grain diameter of not more than 1.5 μm.
摘要翻译:具有优异的烘烤淬透性和拉伸凸缘性的抗拉强度不低于590MPa的高强度热轧钢板具有以质量%计含有0.040〜0.10%的C的化学组成,不超过Si 不超过0.3%,Mn为1.7〜2.5%,P为0.030%以下,S为0.005%以下,Al为0.1%以下,N为0.006〜0.025%,其中贝氏体相为不 小于60%,铁素体相和珠光体相的总和为10%以下,贝氏体相为含有不少于1.4×104个/ mm 2的渗碳体粒子的晶粒,渗碳体为 平均粒径不大于1.5μm。
摘要:
A high strength galvanized steel sheet includes a steel sheet which is a base sheet and a galvanized layer on a surface of the steel sheet, the steel sheet has a composition including, by mass %, 0.08 to 0.15% of C, 0.5 to 1.5% of Si, 0.5 to 1.5% of Mn, 0.1% or less of P, 0.01% or less of S, 0.01 to 0.1% of Al, 0.005% or less of N, and the balance Fe with inevitable impurities, and a microstructure composed of 75 to 90% of a ferrite phase as a main phase and 10 to 25% of a second phase including at least pearlite in terms of an area fraction with respect to the entire microstructure; an average grain size of the pearlite is 5 μm or smaller; and the pearlite has an area fraction of 70% or greater with respect to the total area of the second phase.
摘要:
A high strength galvanized steel sheet having excellent formability, includes a steel sheet which is a base sheet and a galvanized layer on a surface of the steel sheet, wherein the steel sheet is a high strength steel sheet which has a composition including, by mass %, 0.08 to 0.15% of C, 0.5 to 1.5% of Si, 0.5 to 1.5% of Mn, 0.1% or less of P, 0.01% or less of S, 0.01 to 0.1% of Al, 0.005% or less of N, and the balance Fe with inevitable impurities, and a microstructure composed of 75 to 90% of a ferrite phase as a main phase and 10 to 25% of a second phase including at least pearlite in terms of an area fraction with respect to the entire microstructure; an average grain size of the pearlite is 5 μm or smaller; and the pearlite has an area fraction of 70% or greater with respect to the total area of the second phase.
摘要:
A method for manufacturing a high strength hot rolled steel sheet includes heating a slab to a temperature in the range of 1150 to 1300° C.; hot rolling the slab with a finishing rolling temperature being in the range of 800 to 1000° C.; cooling the steel sheet at a mean cooling rate of 30° C./s or higher to a cooling termination temperature in the range of 525 to 625° C.; suspending cooling for a time period in the range of 3 to 10 seconds; cooling the steel sheet in such a manner that cooling of the steel sheet is nucleate boiling; and coiling the steel sheet at a temperature in the range of 400 to 550° C.
摘要:
A steel sheet excellent in FB performance and also excellent in fabrication performance after FB working and a manufacturing method of the same are provided. The steel sheet is a steel sheet having a composition containing from 0.1 to 0.5% of C, not more than 0.5% of Si and from 0.2 to 1.5% of Mn in terms of % by mass, with P and S being adjusted at proper ranges and having a structure having a ferrite having an average grain size of more than 10 μm and less than 20 μm and a cementite present in the ferrite grain having an average particle size of from 0.3 to 1.5 μm. In this way, the steel sheet becomes a steel sheet excellent in FB performance, mold life and performance (side bend elongation) after FB working.