A New Model for Predicting Oxide-Related Defects in Aluminum Castings

The formation of oxide-related defects, including entrained oxide inclusions and oxide-induced gas/shrinkage porosity, during cavity fill and solidification has been inextricably linked to reduced mechanical properties in aluminum castings. Although the oxide formation and entrainment process can be easily understood, it remains difficult to accurately predict the location and severity of oxide-related defects in solidification products. To address the lack of predictive capability, the oxide entrainment number (OEN) model was developed and coupled to a three-dimensional, computational fluid dynamics software to accurately predict both the location and severity of oxide-related defects in aluminum castings. This first computationally efficient model for such application was validated on a geometrically complex aluminum casting where the predictive capability was confirmed via X-ray computed tomography (CT). Additionally, the OEN model can be used to aid in location-specific property prediction as tensile samples taken from the casting showed a reduction in mechanical properties in regions of high defect concentrations predicted by the OEN. The validation of the new OEN model provides a crucial link in an integrated computation materials engineering framework for design and manufacturing of high-quality cast components.