CONTINUOUSLY CAST SLAB, CONTINUOUS CASTING METHOD THEREOF AND PRODUCTION OF THICK STEEL PLATE

摘要

PROBLEM TO BE SOLVED: To provide a continuously cast steel slab which has little center segre gation and V segregation and does not generate an internal crack even in the case of hot-rolling the slab into a thick steel plate, and a continuous casting method of this cast slab and a producing method of the thick steel plate by hot-rolling this cast slab.;SOLUTION: A cast slab 2 is provided with a casting structure constituted with equiaxed crystal at the center part in the cross section and dendritic columnar crystal and columnar crystal in the surroundings or the columnar crystal, is a negative segregation range in the equiaxed crystal part or the equiaxed crystal and the surrounding part and contains 0.02-0.6 wt.% carbon. At the time of casting, after bulging the cast slab by 5-25% of the thickness of the cast slab at the time of starting the bulging and before starting the generation of the equiaxed crystal, the rolling reduction is performed to the thickness corresponding to the bulging quantity with one pair of rolls 4. This cast slab 1 is used and the thick steel plate is produced under an ordinary condition.;COPYRIGHT: (C)2000,JPO