5th International Conference on Advances in Solidification Processes (ICASP-5) 5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining (CSSCR-5)

The simultaneous prediction of macrosegregation and columnar to equiaxed transition (CET) in metal casting is still an important challenge. One of the open questions is the role of melt convection on the CET and the effect of the CET on macrosegregation. A three-phase Eulerian volume-averaged model for macrosegregation and CET is developed. The model uses our recently-developed accurate constitutive relations for equiaxed solidification. It accounts for columnar dendrite tip undercooling and nucleation of equiaxed grains ahead of the columnar tips. The model is used to perform macrosegregation and CET simulations for a numerical benchmark problem involving solidification of a lead-18 wt. pct. tin alloy in a side-cooled cavity. Simulations are performed for different values of the dendrite tip selection and nucleation parameters. As the value of the dendrite tip selection parameter is increased, the predicted number and depth of channel segregates decreases significantly and the grain structure transitions from mixed columnar/equiaxed to fully columnar.