| 摘要 |
The present invention provides a high-strength steel sheet having a tensile strength (TS) of at least 780 MPa, excellent ductility and fatigue characteristics, achieving a balance of high strength and ductility, and having excellent surface quality and sheet-conveying properties, achieved by: having a specific component composition; the steel structure having, in terms of area ratio, 20-50% ferrite, 5-25% bainitic ferrite, and 5-20% martensite, and having, in terms of volume fraction, at least 10% retained austenite; the average crystalline particle diameter of the retained austenite being not more than 2μm; the average Mn volume (mass%) in the retained austenite being at least 1.2 times the Mn volume (mass%) in the steel; and the mean free path of the retained austenite being not more than 1.2μm. |
