Free Surface Model to Predict the Influence of Shrinkage Cavities on the Solute Redistribution in Castings

摘要

The final distribution of macrosegregations in castings is strongly influenced by the solidification behavior and the movement of the melt surface. The last point to solidify is identical to the area of the maximally enriched melt. The present work uses a 2D control-volume-method (CVM) model based on volume-averaging to predict the transient shape of the surface and the shrinkage cavity as well as their influence on the final solute distribution. The solute transport mechanisms are feeding flow, thermo-solutal convection and macroscopic diffusion in the liquid. Mushy zone flow is described by an anisotropic permeability model. The moving surface is realized by implementing a volume-of-fluid model. Phase transitions are calculated using nonlinear eutectic or peritectic phase diagrams taking into account one liquid and two solid phases.