THE INFLUENCE OF METAL-ENTRY ON MACROSEGREGATION IN THE DC-CASTING OF ALUMINUM-COPPER ALLOYS

摘要

In DC-casting practice, different methods of metal-entry are in practical use to control surface quality and start-up procedures. In the casting of alloys it has, however, also an effect on the macrosegregation. In this paper we present modeling results for the metal flow and solidification behavior of a binary Al-Cu alloy during DC casting of cylindrical ingots with four different metal-entry/mould configurations. The results are obtained with the commercial CFD package CFX-4.3, with additional user subroutines for solidification and segregation. In the model, both shrinkage and natural convection due to thermal and solutal buoyancy are taken into account. The solid phase is assumed to flow with the casting velocity. The different sump flow fields and mushy zone characteristics are analyzed to explain the differences in the concentration profiles.