ON THE INTERACTION BETWEEN MACROSEGREGATION, SHRINKAGE FLOW AND GRAIN MOVEMENT

摘要

A two-phase volume averaging model was used to study convection and grain movement, and their influence on the formation of macrosegregations. In the model both liquid and solid phases were treated as separate interpenetrating continua. The mass, momentum, species and enthalpy conservation equations for each phase and a grain transport equation were coupled. An ingot casting (Al-4 wt.% Cu) with near globular solidification morphology was simulated. Different formation mechanisms for negative and positive segregated regions are discussed. The importance of grain movement for the formation of macrosegregations is demonstrated by comparing two distinct cases: one with grain movement and shrinkage flow and the second with only shrinkage flow.