Effect of thixocasting and heat treatment on the tribological properties of hypoeutectic Al–Si alloy

This paper presents results of structural, mechanical and tribological tests of thixocast hypoeutectic Al–Si alloy A356 (EN AlSi7Mg0.3). The pin-on-disc tribometer was used to carry out tribological tests under dry sliding conditions at different loads. Two sets of specimens were used as pin materials. The first one was taken from the original alloy billet and the second one from thixocast alloy. Heat treatment was applied on both sets of specimens. The results showed that, for all applied loads, heat treatment improved tribological properties, while improvements caused by additional thixocasting were not systematic, i.e. lower friction coefficient was noticed just for lower specific loads. Overall better wear resistance of thixocast materials, compared to the originally alloy, was attributed mainly to their higher silicon content.