| 摘要 |
PURPOSE:To attain the high productivity and energy saving while maintaining the regularity in the successive hot rolling passes, by continuously casting the molten steel containing C, O2, S, components with the adjusted Mn/S ratio, and by performing the hot edging pass under the specified strain rate and the pass condition. CONSTITUTION:The component of the molten steel is specified as follows; 0.01- 0.25% C,<=150ppm 02,<=0.03% S, and >=10 Mn/S ratio. This molten steel is continuously cast to obtain the hot cast slab which is then subjected to the hot edging pass by the <=5/sec strain rate and the 50mm./one side/pass or larger breadth reduction; after that, the slab is fed to the hot rolling pass. By thus adjusting the component of the molten steel, the precipitates are made spheroidal or coarse grains, and the generation of cracks is prevented. Besides, by this edging pass, the generation of transverse cracks in the billet surface or the edge cracks in the billet edge is prevented. Accordingly, the cracks are not caused at the successive continuous hot rolling passes, and the flaws do not remain in the product. |
