Role of second-phase particles in chip breakability in aluminum alloys

To evaluate chip breakability, turning tests for various wrought aluminum (Al) alloys were carried out with a cemented carbide tool (K10) in dry and wet cutting conditions. In the alloys, Al2Cu, Al6Mn, Mg2Si, Al–Fe–Si system compounds and eutectic Si were observed as second-phase particles. Chip breakability of the alloys containing Al2Cu or Si were superior to those of those containing Mg2Si or Al–Fe–Si. This tendency was more prominent in wet cutting than in dry cutting. The second-phase particles of Al2Cu and Si in these alloys fractured during the machining process. It was estimated that the fractured second-phase particles acted as the cause of chip breaking. Moreover, the increase of the chip breakability in wet cutting was attributed to the Rehbinder effect due to the penetration of cutting oil into the micro-cracks.