| 摘要 |
PURPOSE:To obtain an unnormalized high-tensile steel material easy to cold work by hot rolling and cold working a steel having specified B, N and Al contents and subjecting it to reheating and finish hot rolling. CONSTITUTION:A steel consisting of <=0.30% C, 0.01-1.00% Si, 1.5-2.5% Mn, 0.01-0.15% Nb, 0.05-0.20% Al, 0.0005-0.0025% B, 0.0025-0.0150% N and the balance Fe with inevitable impurities or further contg. one or more among <=0.15% V, <=1.0% Ni, <=1.0% Cr, <=0.50% Cu and <=0.5% Mo is refined. The steel is heated to >=1,200 deg.C, hot rolled, and cold worked. It is then reheated to >=1,200 deg.C and subjected to finish rolling. By this method an unnormalized high- tensile steel material which can be cold worked easily and has high strength as hot worked is obtd. |
