Comparison of Machinability Performances in Milling of Al-7Si-Mg and Al-7Si-0.6Mg Alloys

Abstract

In this study, the microstructural, mechanical and machinability properties of Al-7Si-Mg and Al-7Si-0.6Mg casting alloys were experimentally researched. While the microstructures of the alloys were determined by optical microscope, the hardness values were determined by Brinell method, elongation to fracture, yield (YS) and tensile strength (TS) values were measured by tensile tests. Milling experiments were performed 6 mm diameter of uncoated carbide end mill which two flutes in CNC vertical machining center using different cutting speeds (V), feed rates (f) and a constant depth of cut (DoC). In microstructural examinations, it was observed that the microstructure of the Al-7Si-Mg alloy comprised of a-Al, primary Si, eutectic Al-Si, Mg2Si, B-Al(Fe, Mn)Si, β-Al5FeSi and π-AlSiMgFe phases. In addition to the existing phases, B-Al8Mg3FeSi6 phase was formed in the microstructure of the Al-7Si-0.6Mg alloy. Al-7Si-0.6Mg alloy exhibited higher hardness, YS and TS and lower elongation to fracture (EF) values compared to Al7Si-Mg alloy. In the milling tests, it was stated that the cutting force (CF), built-up layer (BUL) and builtup edge (BUE) reduced with the increment of the V, while it increased with the increment of the