| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-strength hot rolled steel sheet which has a strength (TS) of 590 MPa or more and is excellent in extensibility and formability for extension flange, and to provide a method of manufacturing the high-strength hot rolled steel sheet. SOLUTION: The high-strength hot rolled steel sheet has a composition containing, by mass, 0.05 to 0.3% C, 0.3 to 2.5% Si, 0.5 to 3.5% Mn, 0.003 to 0.100% P,≤0.020% and 0.010 to 0.5% Al, and the balance iron with inevitable impurities, As for the structure, the area ratio of a ferrite phase is≥20%, that of a tempered martensite phase is 10 to 60%, that of a martensite phase is 0 to 10% and the volume ratio of a retained austenite phase is 3 to 15%. COPYRIGHT: (C)2011,JPO&INPIT |
