THE SOLIDIFICATION STRUCTURE REFINEMENT OF SWRCH22A STEEL BILLET UNDER PULSE MAGNETO-OSCILLATION TREATMENT

摘要

The solidification structure in the continuous casting of SWRCH22A steel billet (240 mm × 240 mm) with Pulse Magneto-Oscillation (PMO) treatment was investigated. The length of columnar dendrites of the billet decreased from 8 cm to 4 cm after PMO treatment, i.e. the area percent of equiaxed dendritic structure zone increased by 30%. Meanwhile, the center shrinkage of billet was significantly modified. PMO substantially promoted the nucleation near the solid/liquid interface and drove the equiaxed grains to move to the center of the melt. In addition, the growth of the columnar dendrite was restrained owing to the Joule heat induced by PMO, concentrating on the out parts of the billet. The results indicated that the PMO was a promising technique for solidification structure homogenizing in continuous casting of steel billet.