PURPOSE: To enable non-cleaning rolling for a stainless steel cast slab by selecting mold cooling, mold material, powder characteristic, etc., in order to uniformize the solidifying speed of the top part and the bottom part of an oscillation mark on the cast slab.
CONSTITUTION: In the cast slab cast by continuous casting, the ratio (S B)/(S T) of a secondary dendritic arm interval (S B) at the bottom part of the oscillation to a secondary dendritic arm interval (S T) at the top part of the oscillation below the surface shell of this cast slab at 150-250μm is made to be <1.4. In the case this ratio (S B)/(S T) becomes ≥1.4, the breakage of solidified shell is caused, and the larger the ratio of these secondary arm intervals is, the deeper a segregation zone is. As to the solidifying speed at the top part and the bottom part, that at the bottom part is ordinarily lower than at the top part, but by making this ratio almost ≥0.5, the segregation zone can be prevented. By this method, the non-cleaning rolling can be attained, and by saving the cleaning to the cast slab, the cost can be reduced.
TANAKA SHIGENORI
YANAI TAKASHI
NAKANO TAKESHI
