| 摘要 |
PROBLEM TO BE SOLVED: To provide a super-high tensile strength cold-rolled steel plate having excellent elongation and elongation-flanging properties, and a method for manufacturing the same. SOLUTION: The steel used has a composition consisting of, by mass, 0.04-0.070% C, 0.5-1.5% Si, 1.8-3% Mn,≤0.02% P,≤0.01% S, 0.01-0.1% Sol.Al,≤0.005% N, and the balance Fe with inevitable impurities. A metal structure of the steel plate is a two-phase structure and substantially contains the ferritic phase and the martensitic phase. The tensile strength is≥780 MPa and <980 MPa. COPYRIGHT: (C)2004,JPO
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