| 摘要 |
The invention provides a high strength steel sheet having excellent ductility which can avoid sudden breakage when being press-formed and has TS of 700 to 900 MPa, and a method for manufacturing such steel sheets. The high strength steel sheet having excellent ductility has a chemical composition represented by, in terms of % by mass, C: 0.5 to 1.5%, Si: not more than 0.1%, Mn: 10 to 25%, P: not more than 0.1%, S: not more than 0.05%, Al: not more that 0.1%, Ni: 3.0 to 8.0%, Mo: not more than 0.1%, N: not more than 0.01%, and Fe and inevitable impurities: balance, and has a microstructure formed of recrystallized austenite grains with an average grain diameter of 5 to 30 µm or further has another microstructure at an area ratio of not more than 1%. |
