| 摘要 |
The present invention provides a high strength press-formed member, characterized in that a steel sheet constituting the member has a composition including by mass %, C: 0.12% to 0.69% (inclusive of 0.12% and 0.69%), Si: 3.0% or less, Mn: 0.5% to 3.0% (inclusive of 0.5% and 3.0%), P: 0.1% or less, S: 0.07% or less, Al: 3.0% or less, N: 0.010% or less, Si + Al: at least 0.7%, and remainder as Fe and incidental impurities, wherein microstructure of the steel sheet constituting the member includes martensite, retained martensite, and bainite containing bainitic ferrite, area ratio of said martensite with respect to the entire microstructure of the steel sheet is in the range of 10% to 85% (inclusive of 10% and 85%), at least 25% of said martensite is tempered martensite, content of retained austenite is in the range of 5% to 40% (inclusive of 5% and 40%), area ratio of said bainitic ferrite in said bainite with respect to the entire microstructure of the steel sheet is at least 5%, the total of area ratios of said martensite, said retained austenite, and said bainitic ferrite in said bainite with respect to the entire microstructure of the steel sheet is at least 65%, and the average carbon concentration in the retained austenite is at least 0.65 mass %. As a result, there can be obtained a high strength press-formed member having high tensile strength of at least 980 MPa and excellent ductility of TS x T. EL. ‰¥ 17000 (MPa %). |
