The influence of oxide inclusions on the fluidity of Al–7 wt.%Si alloy

Recycling of aluminium alloys often increases the volume fraction of oxide inclusions and this may influence the castability of the material. In this study, the fluidity of three Al–7 wt.%Si alloys, namely a standard A356, A356 with 20% scrap addition, and A356 with 50% scrap addition, is reported. The scrap additions consist of contaminated alloy turning chips. Fluidity measurements were performed in an experimental fluidity test consisting of gravity casting of spirals in sand moulds with good reproducibility. The influence of oxide content and percentage of recycled material on the fluidity of the alloys were studied. The results show that recycled material increases the oxide content of the molten metal, which significantly decreases its fluidity. Comparisons between the fluidity measurements on 20 and 50% scrap additions, however, do not show significant differences.