HIGH-STRENGTH PRESSED MEMBER AND METHOD FOR PRODUCING SAME

摘要

The disclosed method obtains a high-strength pressed member having a tensile strength of at least 980 MPa and excellent ductility of TS×T.EL = 17000 (MPa·%) by means of: the composition of the steel sheet configuring the member containing, by mass, at least 0.12% and no more than 0.69% C, no more than 3.0% Si, at least 0.5% and no more than 3.0% Mn, no more than 0.1% P, no more than 0.07% S, no more than 3.0% Al, and no more than 0.010% N, Si + Al being at least 0.7% and the remainder being Fe and unavoidable impurities; the structure of the steel sheet configuring the member having martensite, residual austenite, and bainite containing bainitic ferrite; the area ratio of said martensite to the total steel sheet structure being at least 10% and no more than 85%; at least 25% of said martensite being tempered martensite; the amount of said residual austenite being at least 5% and no more than 40%; the area ratio of bainitic ferrite in said bainite to the total steel sheet structure being at least 5%; the total of the area ratio of said martensite, the area ratio of said residual austenite, and the area ratio of said bainitic ferrite in the bainite to the total steel sheet structure being at least 65%; and the average amount of C in the residual austenite being at least 0.65%.