| 摘要 |
To provide a high strength steel sheet excellent in warm stamp formability and a method for manufacturing the same. A steel having a composition containing, in terms of % by mass, C : 0.01 to 0.2%, Si : 0.5% or lower, Mn : 2% or lower, P : 0.03% or lower, S : 0.01% or lower, Al : 0.07% or lower, and N : 0.01% or lower and further containing one or two or more elements selected from Ti, Nb, V, Mo, W, and B is successively subjected to a hot rolling process including heating to an austenite single phase temperature range, performing hot rolling at a finish rolling end temperature of 860°C or higher, and then coiling at a temperature of 400°C or higher and lower than 600°C and a heat treatment process including performing heat treatment in a temperature range of 650 to 750°C. Thus, a steel sheet excellent in warm stamp formability having tensile properties in which the local elongation is larger than the uniform elongation at a test temperature of 400°C or higher and tensile properties in which the uniform elongation is 40% or more in terms of ratio to the total elongation at a test temperature of lower than 400°C and further having a matrix, which is substantially a ferrite single phase and a structure in which alloy carbides having a size of lower than 10 nm are dispersed and deposited in the matrix in a state having no variant selection. |
