CONTINUOUS CASTING METHOD FOR CAST SLAB

摘要

A main purpose of the present invention is to provide a continuous casting method for a slab satisfying reductions of center segregation and center porosity, and inhibitions of surface cracks and internal cracks of a slab. The present invention is a continuous casting method for a slab including a step of carrying out reduction on a slab having a round cross section and an unsolidified portion inside thereof by cylindrical horizontal rolls to form a pair of parallel surfaces to the slab and a step of alternatively carrying out reduction on the slab completely solidified by a pair of cylindrical horizontal rolls and a pair of cylindrical vertical rolls to form a pair of parallel surfaces vertical to the pair of parallel surfaces, wherein in the former step, reduction ratio of the slab by each pair of the rolls is more than 0.5% and no more than 3% and a ratio of a width of the unsolidified portion at the cross section of the slab to a width of a contact part of the slab and the rolls is 0 to 7.15, and in the latter step, each of reduction ratios of the slab by the horizontal rolls and the vertical rolls is 5.4% to 6.8.