Low frequency electromagnetic casting of large size za21 magnesium alloy slab ingot

Surface quality and microstructure of ZA21 magnesium slab ingots by the direct-chill (DC) casting and low frequency electromagnetic direct chill casting (LFEC)were Deeply and systematically investigated. The surface quality of alloy ingot by LFEC casting is better than that without electromagnetic casting. The crack of ingot was avoided by applying electromagnetic field. The microstructure of ingot without electromagnetic field is coarse columnar grains, on the contrary, the microstructure of ingot by applying electromagnetic field is uniform equiaxed grains. The electromagnetic field can accelerate the flow of the melt and make the dendrite arm break to form equiaxed grains. In addition, the flow of the melt reduces the stress concentration in the solidification process, so that the crack can be avoided.