Influence of the casting and mould temperatures on the (micro)structure and compression behaviour of investment-cast open-pore aluminium foams

Abstract

Current literature offers only limited information about the influence of the casting and mould temperatures on the properties of cast aluminium foams. In order to close this current research gap, the casting and mould temperatures were varied during the production of investment-cast open-pore A356 foams. The results show that a decreased mould temperature and an increased casting temperature lead to increased mechanical properties during the static compression testing of open-pore 10 and 15ppi (pores per inch) A356 foams. This increase is due to a reduced number of eutectic silicon particles and increased strut diameter resulting from the better mould-filling ability of the melt. The effect of the process parameters is statistically significant for the mechanical properties of the 15ppi foams. This is probably due to this foam type’s lower strut diameter; compared to the bigger 10ppi foam struts, since these thinner struts are more sensitive to the high number of the silicon phase and to the decreased strut diameter due to a reduced mould-filling ability. In addition to this, a change of the cooling rate has a larger impact on small strut diameters. With the aid of the present results, the influence of the process parameters on the mechanical properties of open-pore 15ppi foams was modelled and confirmed by reference test runs.