| 摘要 |
PURPOSE:To produce a hot-rolled high tensile steel plate of high workability by rolling and coiling steel contg. C, Si, Mn, S, and Nb or V respectively at prescribed ratios by adequately controlling hot rolling conditions, particularly hot rolling temp. and draft. CONSTITUTION:Steel contg. 0.02-0.20% C, 0.2-1.5% Si, 0.6-2.0% Mn, <=0.005% S, 0.005-0.03% Nb, or <=0.20% V is prepared. Thence, this steel is rolled at <=900 deg.C and >=50% draft, and at >=Ar3 point, after which it is coiled at <=600 deg.C, whereby the Nb of said components is deposited as finely as possible. Thereafter, the coiled steel strip is heated for 2-5min at >=800 deg.C and <=Ac3 temp., and is cooled at >=5 deg.C/sec cooling rate, whereby the intended hot-rolled high tensile steel plate of high workability is obtained. |
