Effect of solution heat treatment on gas porosity and mechanical properties in a die cast step test part manufactured with a new AlSi10MnMg(Fe) secondary alloy

Abstract

The effect of heat treatment on gas porosity and mechanical properties was investigated in a step test part manufactured by vacuum assisted high pressure die casting using a new AlSi10MnMg(Fe) secondary alloy. Porosity and mechanical properties were investigated in the T6 temper with different solution heat treatments. Porosity was characterized by metallographic and fractographic analysis of the tensile specimens. Mechanical properties comparable to the corresponding primary alloy have been achieved for each solution heat treatment. It was found that increasing the solution temperature and time increased the yield and ultimate tensile strength, while elongation decreased and porosity observed on the metallographic sections and fracture surfaces increased. Porosity evaluation on the fracture surfaces indicates that the local area fraction rather than the one observed on the whole fracture surface determines ductility. The size of the largest pore appears to become more relevant above values of 200µm.