| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-strength hot-dip galvanized steel sheet having≥780 MPa tensile strength TS and having excellent pore expandability and bending properties, and to provide a production method therefor. SOLUTION: The high-strength hot-dip galvanized steel sheet having excellent formability, has the component composed of, by mass, 0.03-0.15% C, 0.8-2.5% Si, 1.0-3.0% Mn, 0.001-0.05% P, 0.0001-0.01% S, 0.001-0.1% Al, 0.0005-0.01% N, 0.1-2.0% Cr and the balance Fe with inevitable impurities, and has a micro-structure wherein≥50% ferritic phase and≥10% martensitic phase are included in an area ratio and the above ferritic phase is composed of polygonal ferritic phase and bainitic-ferritic phase, the area ratio of the bainitic-ferritic phase to the ferritic phase is 20-80%, and the average grain diameter of the martensitic phase is≤10μm. COPYRIGHT: (C)2009,JPO&INPIT
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