| 摘要 |
<p>A steel sheet containing C, Si, Mn, P, S, Al, Mo, Ti, B and N, which has a Z value of 2.0 to 6.0 as calculated by the following formula and contains at least 1% of retained austenite and at least 80% (in total) of bainitic ferrite and martensite in terms of area fraction based on the whole structure and which has an average axial ratio of the retained austenite grains of 5 or above and exhibits a tensile strength of 980MPa or above: Z = 9x[C]+[Mn]+3x[Mo]+490x[B]+7x[Mo]/{100x([B]+0.001)} Thus, the invention provides a high-strength steel sheet which has a tensile strength of 980MPa or above and is enhanced in hydrogen embrittlement resistance and a hot-rolled steel sheet for cold rolling which enables the production of the above high-strength steel sheet with high productivity and which is improved in cold rollability. ® KIPO & WIPO 2009</p> |
