Meso-scale modelling of semi-solid deformation in aluminum foundry alloys: Effects of feeding and microstructure on hot tearing susceptibility

Abstract

In the context of hot tearing susceptibility, the semi-solid constitutive behaviour of two commercially important foundry aluminum alloys at high solid fraction has been simulated. The numerical methodology combines solid mechanics, computational fluid dynamics, and microstructure modelling, i.e a meso-scale multi-physics approach. Feedable and un-feedable domains with different microstructures including equiaxed globular, equiaxed dendritic, and combined dendritic and eutectic were developed. Considering that it is the combined effects of a lack of liquid feeding and limited semi-solid ductility that contribute to hot tearing formation, the effect of feeding and mechanical deformation are studied and discussed. The model demonstrates that the microstructure type and the eutectic formation also have a considerable effect on the liquid channels pressure drop and semi-solid bulk stress and strain, and consequently on hot tearing.