| 摘要 |
PURPOSE:To produce an extra mild steel sheet for cold rolling economically by blooming the steel which consists of specific composition and of which the relation of C and Mn in particular is specified, and finish rolling the same at above the temp. determined through operation from Ar3 transformation point according to B contents. CONSTITUTION:The steel consisting of <=0.10% C, <=0.50% Mn, <=0.10% Si, <=0.020% P, <=0.020% S, 5-50ppm B and the balance iron with unavoidable impurities where C+1/6Mn<=0.14% is subjected to ingot making, soaking and blooming. In direct hot rolling of this steel, the finish rolling is finished at the temp. above Ar3-0.5XB deg.C based on the Ar3 transformation point of the steel of the case when no B is contained. Since temp. conditions are eased by this method, rolling is easier and the restrictions of coiling temp. etc. is decreased by the effect of improving softening and aging characteristics. |
