Machinability properties of Al-7Si, Al-7Si-4Zn and Al-7Si-4Zn-3Cu alloys

Abstract

Al-7Si, Al-7Si-4Zn, Al-7Si-4Zn-3Cu alloys were produced by permanent mold casting method to investigate the effects of copper and zinc additions on the machinability properties of Al-7Si alloy. the structural and mechanical properties of the produced alloys were investigated with conventional methods. Machinability properties of these alloys were determined by turning, and they were associated with structural and mechanical properties of the alloys. Machinability experiments were carried out in CNC vertical machining center under dry cutting conditions using uncoated carbide drill and constant cutting speed (120 m/min), feed (0.15 mm/rev) and depth of cut (15 mm) values. the microstructure of Al-7Si binary alloy was observed to be composed of aluminum-rich alpha phase, primary silicon crystals and eutectic Al-Si phase. the addition of 4% Zn to the Al-7Si alloy did not form a different phase in the microstructure. However, Al2Cu intermetallic phase was formed by addition of 3% Cu. While the hardness and tensile strength of the alloy increased, elongation to fracture significantly reduced. As a result of machinability experiments, it was observed that the minimum thrust force and surface roughness occurred in Al-7Si-4Zn-3Cu alloy, while the maximum built-up edge was observed during drilling of Al-7Si and Al-7Si-4Zn alloys. Microhardness value of machined surface in Al-7Si alloy was found to be the minimum while the maximum Al-7Si-4Zn-3Cu alloy was observed.