Predicting the constitutive behavior of semi-solids via a direct finite element simulation: application to AA5182

Abstract

The methodology of direct finite element simulation was used to predict the semi-solid constitutive behavior of an industrially important aluminum-magnesium alloy, AA5182. Model microstructures were generated that detail key features of the as-cast semi-solid: equiaxed-globular grains of random size and shape, interconnected liquid films, and pores at the triple-junctions. Based on the results of over fifty different simulations, a model-based constitutive relationship which includes the effects of the key microstructure features – fraction solid, grain size, and fraction porosity – was derived using regression analysis. This novel constitutive equation was then validated via comparison to both the finite element simulations and experimental stress/strain data. Such an equation can now be used to incorporate the effects of microstructure on the bulk semi-solid flow stress within a macro scale process model.