| 摘要 |
PROBLEM TO BE SOLVED: To prevent the generation of crack on the surface of a steel slab having low hot woakability and to obtain a high quality steel material with a rolling into a product thereafter by rapidly cooling the cast slab surface which is obtd. by continuously casting a high sulfur steel to make fine of the crystal grain, heating in a heating furnace after forming the fine structure and bloom-rolling. SOLUTION: The molten high sulfur steel 2 containing >0.10 wt.% S and if necessary, 0.10-0.35% Pb and further, <0.05% P, is poured into a water- cooling mold 4 through a tundish 3 from a ladle 1 and a produced outer shell- solidified cast slab 5 is cooled in a spray zone 6, and after drawing out and straightening with pinch rolls 7, the solidified cast slab 8 is cut off into a prescribed length with a cutting device 9. The obtd. cast slab at about 680 deg.C is water-cooled and the surface is rapidly cooled at about 420 deg.C to make fine of the crystal grain on the surface. Successively, this cast slab is charged into the heating furnace and extracted at >=1230 deg.C and the bloom-rolling is executed. In this way, the generation of crack on the surface of the steel slab is prevented, and even in the case of generating the crack, the high sulfur steel material having low hot workability, in which the depth of crack is shallow, is obtd.
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