Microstructural characteristics of Alloy 718 and Waspaloy and their influence on flank wear during turning

The present study deals with the influence of the microstructures of two wrought superalloys on the flank wear of uncoated cemented tungsten carbide tools in turning. Tool life tests have been performed in order to compare the flank wear development during machining of Alloy 718 and Waspaloy. Additionally, microstructural aspects, such as hardness, grain size as well as types and quantities of hard, abrasive phases have been determined and compared for both machined superalloy workpieces. The results show that Alloy 718 is associated with faster flank wear progression as compared with Waspaloy. The difference in wear is not likely to be the result of higher thermal and mechanical loads on the tool during machining Alloy 718. Characterization of obtained flank wear topographies after removal of adhered workpiece material revealed that abrasive wear is the dominant wear mechanism during machining both superalloys with the investigated cutting parameters. Varying extents of abrasive tool wear during cutting of the two alloys are therefore the likely reason for the different wear rates. In connection to that, significantly larger quantities of hard phases, specifically primary MC-type carbides and TiN-inclusions were found in the Alloy 718 workpiece which can explain the faster flank wear progression during machining this alloy.