| 摘要 |
PURPOSE:To obtain easily a surface-softened steel plate having high tension as rolled by subjecting a slub contg. prescribed percetages of C, Si, Mn, Al and Nb to heating, rolling and cooling under prescribed conditions. CONSTITUTION:A slub contg., by weight, 0.03-0.2%C, 0.05-0.6% Si, 0.5-2.5% Mn, 0.005-0.65% Al and >=0.01% Nb is heated so that 50-100 deg.C small temp. difference is produced between 1,050-1,150 deg.C surface temp. and the lower central temp. The heated slub is rolled at >=900 deg.C surface temp., 3-5% draft per one pass, >=30% total draft and >=(Ar3+50) deg.C central temp. of the material to be rolled. after the rolling is finished, cooling is carried out from >=(Ar3+20) deg.C central temp. at 5-30 deg.C/sec cooling rate.
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