| 摘要 |
<p>Provided are an ultra high strength cold rolled steel sheet having excellent ductility and bending workability with tensile strength of 980 MPa or more, and a method for manufacturing the same. The ultra high strength cold rolled steel sheet having excellent ductility and bending workability comprises, 0.08-0.12 wt% of C, 0.8-1.2 wt% of Si, 2.6-3.0 wt% of Mn, 0.001-0.10 wt% of P, 0.010% or less of S, 0.01-0.10 wt% of Sol.Al, 0.010% or less of N, 0.2-0.7 wt% of Cr, 0.0010-0.0060 wt% of B, 0.015-0.05 wt% of Sb, 0.005-0.05 wt% of the sum of one kind or more selected from a group consisting of Nb and Ti, and the remainder consisting of Fe and inevitable impurities. Moreover, ferrite and martensite are a main structure. Bainite, tempered martensite, or the sum thereof is 20% or less in a cross-sectional area ratio.</p> |
