| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for removing a surface defect of a cast slab for eliminating the left-over of a surface flaw and resolving the origin of the surface defect in the downstream operation by removing not only a detectable part of the surface flaw of the cast slab but the optimum range including a hardly detectable part of the surface flaw of the cast slab. SOLUTION: At the cooling time of the continuous casting, a cast slab 1 is cooled by pouring water at the cooling temperature immediately before passing an Ar<SB>3</SB>transformation point. The cast slab is cooled at the cooling speed faster than the appearance of a ferrite-pearlite structure. After the cooling, the surface flaw of the cast slab 1 is detected. The whole surface flaw part 2 of the cast slab 1 including 0.5 L length or more of undetected parts B of the surface flaw extending to the outside from both ends of the detected part A of the surface flaw with respect to the detected surface flaw part A (length L) of the cast slab 1 is removed by turning. After the cast slab 1 is heated at the rolling temperature in the heating furnace, the hot rolling is performed, and the cast slab is formed into a billet. COPYRIGHT: (C)2004,JPO
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