| 摘要 |
A steel sheet having (a) a dual phase microstructure with a martensite phase and a ferrite phase and (b) a composition containing by percent weight: 0.01<=C<=0.2; 0.3<=Mn<=3; 0.05<=Si<=2; 0.2<=Cr+Ni<=2; 0.01<=Al<=0.10; 0.0005<=Ca<=0.01, with the balance of the composition being iron and incidental ingredients. Also, the steel sheet is made by a batch annealing method, and has a tensile strength of at least approximately 400 megapascals and an n-value of at least approximately 0.175.
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