HOT STAMPED STEEL, COLD STEELED STEEL SHEET AND METHOD FOR PRODUCING HOT STAMPED STEEL

摘要

A hot-stamped steel according to the present invention has a predetermined chemical composition, satisfies (5 × [Si] + [Mn]) / [C] 10 when [C] is the amount of C by mass%, [Si] is the amount of Si by mass%, and [Mn] is the amount of Mn by mass%, includes 40% to 95% ferrite and 5% to 60% martensite in area fraction, and optionally further includes 10% or less pearlite in area fraction, 5% or less retained austenite in volume fraction, and less than 40% bainite in area fraction. The total of the area fraction of ferrite and the area fraction of martensite is 60% or more, the hardness of martensite measured with a nanoindenter satisfies H2 / H1 1.10 and ÃHM 20, and TS × » which is product of tensile strength TS and hole expansion ratio » is 50000 MPa·% or more.