MODELLING MACROSEGREGATION DURING DC CASTING OF A BINARY ALUMINIUM ALLOY

摘要

A macrosegregation model that describes how alloying elements redistribute under the influence of convection in the mushy zone and bulk liquid during Direct Chill casting of binary aluminium alloys is implemented using three modules: macroscopic transfer module, microsegregation module, and phase diagram calculation module. The macroscopic transfer module adopts a rigid network model, and is implemented by a multi-component flow model in a Computational Fluid Dynamics Software CFX. The microsegregation module includes linear solidification model, lever rule and Scheil equation to describe the relationship for phase fractions and composition as functions of the local temperature and average composition. This implementation can achieve fine meshing of mushy zone and fast computation speed due to the unstructured meshing and parallel computing features provided by the commercial CFD software. Both parametric study of the macrosegregation model and the comparison of the simulation results with the previous reports and our experimental measurements are performed. Numerical oscillations experienced in the earlier research works are significantly reduced.