| 摘要 |
<p>This high-strength steel sheet has a chemical composition containing, by mass%, at least 0.05% and less than 0.10% of C, from 0.20% to 0.50% inclusive of Si, at least 0.20% and less than 1.20% of Mn, from 0.20% to 1.20% inclusive of Cr, from 0.20% to 0.60% inclusive of Mo, from 0.010% to 0.050% inclusive of Nb, from 0.005% to 0.030% inclusive of Ti, from 0.01% to 0.10% inclusive of Al, from 0.0003% to 0.0030% inclusive of B, from 0% to 0.10% inclusive of V, from 0% to 0.50% inclusive of Cu, and from 0% to 0.0030% inclusive of Ca, Ni is limited to no more than 0.1%, P to no more than 0.012%, S to no more than 0.005%, and N to no more than 0.0080%, and the remainder comprises Fe and unavoidable impurities. Pcm is no greater than 0.22%, A is no greater than 2.0, the sum of the compositional fraction of lower bainite and the compositional fraction of martensite is at least 90%, the compositional fraction of the lower bainite is at least 70%, the aspect ratio of prior-austenite grains is at least 2, the yield strength is at least 885 MPa, and the tensile strength is from 950 MPa to 1130 MPa inclusive.</p> |
