Study on the Effect of SEMS on the As-Cast Structure of Steel in Thin Slab Continuous Casting Using an Equiaxed-Columnar Solidification Model

Strand electromagnetic stirring (SEMS) is widely applied in thin slab continuous casting to improve the equiaxed crystal ratio (ECR) of steel. To provide a deeper insight into the role of SEMS in controlling the flow pattern, superheat transportation, macrosegregation, and as-cast structure in the whole strand. A three-phase equiaxed-columnar solidification model was developed to predict the solidification process. The anisotropic permeability of directional columnar structures was integrated into the model by tracking the columnar growing direction. Numerical results showed that two recirculating flow regions came into being under the one-way moving magnetic field induced by the SEMS. The upward recirculating flow deflected the nozzle jet and assembled a superheat melt impinging towards the narrow face under the electromagnetic stirring. Level velocity and level height in the stirring direction were disturbed by the upward flow. Equiaxed grains formed in the stirring direction were less than the volume fraction on the other side. The one-way magnetic field also caused an asymmetric distribution of equiaxed grains in the thickness direction. Applying SEMS was beneficial to the improvement of ECR. The ECR in the strand was 4 pct in the absence of electromagnetic stirring, and it increased to 17.4 pct after applying the SEMS.