| 摘要 |
PROBLEM TO BE SOLVED: To provide a high strength cold rolled steel sheet having a high strength satisfying a tensile strength of≥980 MPa and further provided with uniform and satisfactory bendability. SOLUTION: The high strength cold rolled steel sheet has a chemical composition comprising 0.05 to 0.20% C, 0.1 to 2.0% Si, 1.0 to 3.0% Mn,≤0.10% P,≤0.010% S, 0.001 to 0.20% Al and≤0.020% N, and the balance iron with impurities, and has a structure including bainite of≥95% by an area ratio, wherein the grain sizes of old austenite are≤20μm, and further, the ratio between the maximum grain size and the minimum grain size in the grain sizes of the old austenite in optional three points in the width direction of the steel sheet is≤5.0. COPYRIGHT: (C)2006,JPO&NCIPI
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