| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high-strength steel plate that has both ductility and deep drawability while maintaining strength of not less than 980 MPa class. <P>SOLUTION: The high-strength steel plate includes, in percentages by mass, 0.05-0.3% C, 1-3% Si, 0.5-3% Mn, not more than 0.1% P (including 0%), not more than 0.01% S (including 0%), 0.001-0.1% Al, and 0.002-0.03% N. The remainder has a component composition comprising iron and impurities, and has a structure including, in terms of an area ratio relative to the entire structure, 50-90% bainitic ferrite, 5-20% retained austenite (γ<SB POS="POST">R</SB>), 10-50% martensite plus the γ<SB POS="POST">R</SB>above, and not more than 40% ferrite (including 0%). The γ<SB POS="POST">R</SB>satisfies a concentration C (Cγ<SB POS="POST">R</SB>) of 0.5-1.2 mass%, an average circle equivalent diameter of 0.2-2 μm, and an average aspect ratio (maximum diameter/minimum diameter) of less than 3.0. <P>COPYRIGHT: (C)2012,JPO&INPIT |
