| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high-strength hot-dip galvanized steel sheet which has TS of ≥590 MPa and excellent workability; and a process for the production thereof. <P>SOLUTION: The component composition contains, by mass%, ≥0.05 to ≤0.3% C, ≥0.7 to ≤2.7% Si, ≥0.5 to ≤2.8% Mn, ≤0.1% P, ≤0.01% S, ≤0.1% Al, ≤0.008% N and consisting of the balance iron and inevitable impurities. The structure has, in terms of area fraction, ≥30% to ≤90% of a ferrite phase, ≥3% to 30% of bainite phase, and ≥5% to ≤40% of a martensite phase. In addition, the martensite phase of an aspect ratio ≥3 in the martensite phase exists at ≥30%. More preferably, the composition as ≥2% retained austenite phase in terms of volume fraction is secured, and the mean crystal grain diameter of the retained austenite phase is ≤2.0 μm. <P>COPYRIGHT: (C)2009,JPO&INPIT |
