ABSTRACT
This chapter reviews the application of macroscopic modelling for defect prediction and illustrates how the macroscopic models can be combined with mesoscopic models for the prediction of the solidification microstructure. Linkage of the macro- and meso-scales extends our understanding of how solidification conditions affect the final properties of aluminium shape castings. There are three primary causes of porosity in shape castings: entrapped insoluble gas bubbles, shrinkage porosity and gas porosity. Gas porosity occurs when dissolved gases within the liquid metal come out of solution during solidification due to a reduced solubility in the solid, and form bubbles. The coupling of the length scales between mesoscopic and macroscopic models is costly, therefore the use of empirical and mesomodel derived functions for the prediction of the casting solidification structures are best incorporated into an efficient finite element method macromodel and applied to both casting process selection and optimization.
