| 摘要 |
PURPOSE:To manufacture a cold rolled steel plate with little surface defect, superior deep drawability, bulging property and warm workability by finishing hot rolling of a mild steel slab, under specific conditions, the Mn, S and O contents have been restricted and cooling the resulting plate, followed by coiling, usual cold rolling, annealing and refining. CONSTITUTION:Molten steel is desulfurized and deoxidized to 0<=0.004%, S<= 0.003% and C<=0.05%, and after adding Mn; 0.01-0.06% the steel is cast into a slab by usual ingot making or continuous casting. This mild steel slab is rolled at a finish temp. above the A3 point with a usual continuous hot rolling mill, rapidly cooled to below 600 deg.C at a cooling rate above 100 deg.C/sec, and coiled. Next usual cold rolling, annealing and refining are carried out to manufacture a cold rolled steel plate. In case a non-aging steel plate is manufactured, to the deoxidized and desulfurized molten steel is added Al and/or B in place of the above Mn in an irreducible min. amt. of formula I to N in the steel. |
