5th International Conference on Advances in Solidification Processes (ICASP-5) 5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining (CSSCR-5)

The formation of casting defects, including macrosegregation, shrinkage cavity, porosity, and inclusion, which resulting from the combined action of multi-physics filed, is a complex process. This process including the nucleation, growth, floating (or settling) of both inclusion and equiaxed crystals; growth and fragmentation of dendritic crystals; solidification shrinkage; solute redistribution and migration; etc. Therefore, it is a big challenge to predict these defects together in one model. Based on the dendritic-equiaxed & columnar macrosegregation model, a four-phase solidification model that further consider the gas phase, which supplement the volume reduction of solidification shrinkage, has been established to realize the prediction of shrinkage cavity in metal solidification process. For the prediction of inclusion, in order to distinguish the difference between exogenous and endogenous inclusions, two models had been established respectively: 1) for exogenous inclusions, the coupling of Discrete Phase Model (DPM) and four-phase solidification has been considered, which has the possibility to track the moving of inclusion particle; 2) for endogenous inclusions, inclusion-combined macrosegregation model, which coupling the inclusion growth theory with the multicomponent four-phase solidification model, has been established. The formation process of defects in steel ingots had been investigated by these multi-defects models, which provide reasonable results by compared with experiment results. The interaction behaviors and its mechanisms between shrinkage cavity, inclusion and macrosegregation had been deeply studied.