Patent ID: 11939640
Assignee: JFE STEEL CORPORATION
Field: Materials, metallurgy (Chemistry)
Classification: CPC C  B  Y | IPC B  C

Claim 0:
1. A method for producing a hot-rolled steel sheet, the method comprising:
hot rolling a steel material, of a composition comprising, in mass %, C: 0.05 to 0.12%, Si: 0.80% or less, Mn: 1.30 to 2.10%, P: 0.001 to 0.050%, S: 0.005% or less, Al: 0.01 to 0.10%, N: 0.010% or less, one or more selected from Cr in an amount of 0.05 to 0.50%, and Mo in an amount of 0.05 to 0.50%, one or more selected from Ti in an amount of 0.01 to 0.10%, Nb in an amount of 0.01 to 0.10%, and V in an amount of 0.01 to 0.10%, and the balance Fe and unavoidable impurities, under the conditions where a rolling reduction of a final pass of finish rolling is 12% or more, a rolling reduction of a preceding pass of the final pass is 15% or more, and a finisher delivery temperature is 850 to 950° C.;
subjecting the steel after the hot rolling to first cooling in which the steel is cooled to a cooling stop temperature at a first average cooling rate of 50° C./s or more, the cooling stop temperature being 750° C. or less;
subjecting the steel after the first cooling to second cooling in which the steel is cooled to a coiling temperature at a second average cooling rate of 5° C./s or more and less than 50° C./s; and
coiling the steel after the second cooling at a coiling temperature of 650° C. or less.