| 摘要 |
PURPOSE:To obtain the titled steel, by rolling regulatedly steel slab contg. C, Si, Mn, Al, S, cooling said plate acceleratedly under a specified condition, then holding it at a suitable temp. range. CONSTITUTION:Steel slab contg. 0.005-0.15wt% C, 0.1-0.5% Si, 0.8-2.0% Mn, 0.005-0.08% Al, <=0.008% S is manufactured. Said slab is rolled at Ar3+70 deg.C-Ar3 range by at least 50% draft. Immediately after rolling, accelerated cooling is applied by 2-30 deg.C/s rate, and stopped at <500 deg.C range. Thereafter, said plate is held warmly at <500->=200 deg.C range for 5-30min range. If necessary, >=one kind among Cu, Ni, Cr or >=one kind of Mo, V are added to steel having said compsn. By this way, high tensile steel superior in low temp. toughness and weldability can be manufactured stably in nontempered quality.
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