Effect of Si content on turning machinability of Al–Si binary alloy castings

Abstract

In this study, Al–Si alloy was employed as a specimen which added Si to improve the chip breakability, and the effect of eutectic Si and primary Si on the machinability of the Al–Si alloy was investigated. For chip breakability, eutectic Si made chip thin, and primary Si was cracked during machining and acted as a nucleus of chip breaking. For surface roughness, the effect of eutectic Si was higher than that of primary Si, and eutectic Si reduced the adhesion on cutting edge. The decrease of surface roughness resulted in a corresponding decrease in adhesion on cutting edge. Additionally, the cracking of primary Si was responsible for the increase of surface roughness in hypereutectic alloys. Tool wear was increased with an increase of the number of eutectic Si. In hypereutectic alloys, tool wear was accelerated by the contact between tool and crashed primary Si.