Effect of multi directional forging on microstructure, mechanical and tribological properties of Al-9Si-0,6Mg-0,1Sr alloy

In this study, the effect of multidirectional forging applied in firstly hot and then cold conditions on microstructure, mechanical and tribological properties of the Al-9Si-0,6Mg-0,1Sr alloy was investigated. The alloy was synthesised by the permanent mould casting. It was seen that the dendritic structure of the alloy was eliminated, the hard phases as well as the silicon particles were broken and dispersed homogeneously in microstructure of the alloy with multidirectional forging. It was also seen that homogenous distribution of the hard particles increased with increasing forging cycle. The yield and tensile strength and elongation values of the alloy increased with forging cycle, while the compressive strength decreased. On the other hand, the hardness and microhardness of the alloy reached the highest value after one cycle of multidirectional forging and then decreased with repeating cycles. The cold forging subjected after hot forging resulted an increase in hardness, yield, tensile and compression strengths of the alloy, but it decreased alloy's ductility. The friction coefficient and wear loss of the alloy increased after forging. The cold forging relatively reduced the wear resistance of the hot forged alloy. Dry wear mechanism of the alloy in all states was observed to be adhesion, delamination and abrasion, but adhesion and delamination were more effective mechanisms.