| 摘要 |
PROBLEM TO BE SOLVED: To provide a high strength steel sheet which has high baking hardenability on application of high prestrain where complicated shapes and safety in case of a collision are considered, and to provide a production method therefor. SOLUTION: The high strength steel sheet has a composition containing, by mass, 0.0005 to 0.3% C, 0.001 to 3.0% Si, 0.01 to 3.0% Mn, 0.0001 to 0.05% Al, 0.001 to 0.3% P, 0.0001 to 0.1% S, and 0.0010 to 0.05% N, and the balance Fe with inevitable impurities, and has a structure where ferrite occupies as a phase having the maximum area ratio, and solid solution carbon: Sol.C and solid solution nitrogen: Sol.N in the ferrite satisfy 0.1 to 100, and in which, on application of prestrain in 5 to 20%, the average of yield strength and tensile strength or each value after baking treatment at 110 to 200 deg.C for 1 to 60 min is >=50 MPa.
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