METHOD FOR PRODUCING HOT-PRESSED STEEL MEMBER

摘要

To establish a method for obtaining a hot-pressed steel member, which exhibits high strength, high tensile elongation (ductility) and high bendability, thereby having excellent deformation characteristics at the time of collision crush (collision crush characteristics), and which is capable of ensuring excellent delayed fracture resistance. A method for producing a hot-pressed steel member by heating a steel sheet, which has a chemical component composition containing 0.10% (% by mass, and hereinafter the same shall apply) to 0.30% (inclusive) of C, 1.0% to 2.5% (inclusive) of Si, 1.0% to 3.0% (inclusive) of Si and Al in total and 1.5% to 3.0% (inclusive) of Mn, with the balance made up of iron and unavoidable impurities, and hot pressing the steel sheet one or more times. The method for producing a hot-pressed steel member is characterized in that: the heating temperature is set to not less than the Ac3 transformation point; the starting temperature of the hot pressing is set to not more than the heating temperature but not less than the Ms point; and the average cooling rate from (the Ms point - 150)°C to 40°C is set to 5°C/s or less.