Control Center Segregation in Continuously Cast GCr15 Bloom by Optimization of Solidification Structure

Abstract

Complex electromagnetic stirring technique (M+F-EMS) and low superheat pouring can enlarge the equiaxed crystal zone and fine equiaxed grains, which are beneficial to improve center segregation of continuously cast high-carbon steel blooms. In this work, a cellular automaton-finite element (CAFE) coupling model has been established to predict the solidification process and analyze solidification structure evolution of continuously cast GCr15 bearing steel bloom with 220 mm × 260 mm, in which electromagnetic stirring was taken into consideration. The influences of M-EMS, superheat and casting speed on the solidification process and structure were numerically investigated, in addition, the compactness degree in the central equiaxed crystal zone was also evaluated. The results demonstrate that casting speed has the obvious effect on solidification end and central solid fraction in strand compared with superheat, which is closely related to F-EMS implement position. M-EMS and low superheat exhibit a significant increment on the central equiaxed crystal ratio and the compactness degree in the central equiaxed crystal zone in the bloom, which is closely related to the center solidification time. The industrial trials’ results show that the central equiaxed crystal ratio and center segregation can be improved under optimized lower superheat and higher casting speed with M+F-EMS.