The reliability analysis of using the volume averaging method to simulate the solidification process in a ingot

Abstract

Adopting the Euler and the volume averaging methods, a three-phase mathematical model with parent melt as the primary phase, columnar dendrites and equiaxed grains as two different secondary phases is developed, and the coupled macroscopic mass, momentum, energy and species conservation equations are obtained separately. Taking the Al-4.7 wt% Cu binary alloy ingots for example, the flow field, temperature field, solute field, columnar-to-equiaxed-transition and grain sedimentation in two-dimension are simulated, and the simulated result of ingot and macrosegregation result are compared with their experimental values. The simulation results of temperature field, flow field and structure are basically consistent with the theoretical results, but the result of solute field shows that the simulated values is lower than the measured value on the edge, this is because the model does not take the shrinkage and forced convection into account, and the inner results is higher than the results on edge. The shrinkage and inverse segregation therefore should not be neglected. This model are still necessarily improved. Besides, based on the analysis of simulation results, the advantages and the disadvantages of the volume averaging method to simulate the solidification in a ingot are evaluated.