| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high-strength steel sheet and a high-strength hot-dip galvanized steel sheet having excellent ductility, stretch flange formability and bendability. <P>SOLUTION: The steel sheet has a componential composition comprising, by mass, 0.05 to 0.3% C, 0.01 to 2.5% Si, 0.5 to 3.5% Mn, 0.003 to 0.100% P, ≤0.02% S and 0.010 to 1.5% Al, and in which the total of the contents of Si and Al is 0.5 to 3.0%, and the balance iron with inevitable impurities, and has a metallic structure comprising, by area ratio, ferrite of ≥20%, tempered martensite of 10 to 60% and martensite of 0 to 10%, and comprising, by volume ratio, retained austenite of 3 to 10%, and in which the ratio (m) between the Vickers hardness (m) of the tempered martensite and the Vickers hardness (f) of the ferrite, (m)/(f) is ≤3.0. <P>COPYRIGHT: (C)2011,JPO&INPIT |
