| 摘要 |
<p>The invention relates to a hot-rolled steel sheet having a strength greater than 1200 MPa, an Re/Rm ratio of less than 0.75 and an elongation at break of greater than 10%, the composition of which comprises, the contents being expressed by weight: 0.10% = 0.015%; Si <= 1.985%; Mo < 0.30%; Cr <= 1.5%; S < 0.015%; P = 0.3%, the balance ofthe composition consisting of iron and inevitable impurities resulting from the smelting, and the microstructure of the steel consisting of at least 75% bainite, residual austenite in an amount equal to 5% or higher, and martensite in an amount equal to 2% or higher. ® KIPO & WIPO 2009</p> |
