ON THE IMPORTANCE OF MODELING 3D SHRINKAGE CAVITIES FOR THE PREDICTION OF MACROSEGREGATION IN STEEL INGOTS

摘要

With this work an existing 3-phase mixed columnar-equiaxed solidification model is extend to treat the formation of shrinkage cavity by including an additional phase. In the previous model a mixed columnar and equiaxed solidification approach that considers the multiphase transport phenomena (mass, momentum, species and enthalpy) is proposed to calculate the as-cast structure including columnar-to-equiaxed transition (CET) and formation of macrosegregation. In order to incorporate the formation of shrinkage cavity, a supplementary phase, i.e. gas phase or covering liquid slag phase, is considered in addition to the previously introduced 3 phases (parent melt, solidifying columnar dendrite trunks and equiaxed grains). No mass and species transfer between the new phase and the other 3 phases is necessary, but momentum and energy transfer is of critical importance for the formation of the shrinkage cavity and with that the flow and formation of macrosegregation would be influenced. Some modelling approaches for the momentum and energy transfer are suggested and tested.