| 摘要 |
PURPOSE:To manufacture a thick high-tensile steel plate having excellent low- temperature matting property by a method in which a steel of a given composition is rolled and rerolled under specific conditions, quickly cooled, and then wound up at low temperatures. CONSTITUTION:A steel, containing 0.02-0.25wt% C, <=0.60wt% Si, 0.5-2.2wt% Mn, <=0.010wt% S, <=0.10wt% sol. Al, and Fe and inevitable impurities, together with, as needed, a strength-improving components consisting of one or more of <=0.10wt% Nb, <=0.10wt% V, <=0.10wt% Ti, <=0.50wt% Cu, <=0.50wt% Ni, <= 0.50wt% Cr, and <=0.010wt% B, or one or both of the strength-improving component and <=0.010wt% Ca, is subjected to the following process treatment. That is, the steel is rolled at a processing rate of 50% or more in a temperature region of 1100-950 deg.C, and rerolled at a processing rate of 30% or more in a temperature region of Ar3-Ar1 points. The steel is then quickly cooled to a temperature region of 480 deg.C-Ms point at a cooling rate of 3 deg.C/sec or more and then rolled up. |
