Patent ID: 11965223
Assignee: JFE STEEL CORPORATION
Field: Materials, metallurgy (Chemistry)
Classification: CPC C | IPC C

Claim 3:
4. A method for manufacturing the steel sheet according to claim 2, comprising:
a hot-rolling step of hot-rolling steel material having the component composition according to claim 2;
a cold-rolling step of pickling and cold-rolling a steel sheet after the hot-rolling step; and
an annealing step of heating the steel sheet after the cold-rolling step to 820° C. or higher in an atmosphere with a dew point of −25° C. or lower, starting water quenching at 700° C. or higher to water-cool the steel sheet to 100° C. or lower, and then reheating the steel sheet at 100° C. to 300° C.,
wherein the steel sheet in water cooling for the water quenching in the annealing step is pressed with two rolls placed to hold the steel sheet from front and back surfaces of the steel sheet in a region that the surface temperature of the steel sheet is not lower than (Ms−250° C.) that is a temperature 250° C. lower than the Ms point nor higher than (Ms+150° C.) that is a temperature 150° C. higher than the Ms point, the pressing being performed under conditions that an inter-roll distance between the two rolls is 20 mm to 250 mm and a pressing force is 196 N or more.