| 摘要 |
A high strength steel sheet excellent in formability which has a chemical composition in mass %: C: 0.03 to 0.20%, Si: 0.005 to 0.3%, Mn: 1.0 to 3.1%, P: 0.001 to 0.06%, S: 0.001 to 0.01%, N: 0.0005 to 0.01%, Al: 0.2 to 1.2%, Mo ‰¦ 0.5%, and the balance: Fe and inevitable impurities, with the proviso that the values of mass % for Si and Al satisfy the following formula (1): (0.0012 × [objective value of TS] - 0.29 - [Si])/2.45 < Al < 1.5 - 3 × [Si] .... (1) wherein [objective value of TS] represents a design strength value for the steel sheet in an Mpa unit, and has a metal structure containing ferrite and martensite. The above high strength steel sheet is also excellent in formability and the capability of being chemically treated and that of being hot-dip zinc sheeted. |
