| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-strength cold-rolled steel sheet which has excellent coating film adhesion and workability and satisfies the tensile strength of ≥550 MPa. SOLUTION: The high-strength cold-rolled steel sheet having excellent coating film adhesion and workability is composed of a steel sheet with a composite structure satisfying a prescribed componential composition, and comprising prescribed amounts of ferrite, bainite and retained austenite, and, when the cross-section in the vicinity of the surface of the steel sheet is observed at the magnification power of 2,000 using SEM (scanning electron microscope), cracks with a width of ≤3 μm and a depth of ≥5 μm are not present in optional 10 fields, its tensile strength is ≥550 MPa, and also, the tensile strength (TS: unit MPa) and elongation (El: unit %) satisfy inequality (1) TS×El≥19,000. COPYRIGHT: (C)2011,JPO&INPIT
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