On the probabilistic nature of high-pressure die casting

Abstract

© 2021 The Authors. This article unmasks the probabilistic nature of high-pressure die casting; specifically, the cause of scatter in the tensile ductility of die-cast Al8Si0·4Mn0·3Mg (wt.%) alloy. Scatter in tensile ductility is related to the size of large pores and non-metallic inclusions. We propose that these non-metallic inclusions form during the pyrolysis of commercial plunger lubricants, and that these large pores derive from dilatational strains introduced during semi-solid deformation. The apparent randomness of pore formation is thus ascribed to the heterogeneous nature of the semi-solid network. Reducing heat loss in the shot chamber is shown to promote a more homogeneous grain structure, leading to a decrease in the maximum pore size from 1.32 mm to 0.37 mm, and an increase in the minimum tensile ductility from 6.8% to 9.4%.