Study of flank wear topography and surface-deformation of cemented carbide tools after turning Alloy 718

摘要

An investigation is reported on the characterization of an uncoated tungsten carbide tool used for machining of a Ni-Fe based superalloy (Alloy 718). Scanning electron microscopy (SEM) in combination with white-light interferometry (WLI) was applied to study the flank wear surface topographies both directly after the turning test and when the adhered workpiece material was removed by etching. The obtained results show that the thin layers of adhered workpiece material present on the flank wear land can obscure the wear topography. Removal of adhered workpiece material from the worn areas of interest is therefore necessary to reveal features of worn tool surfaces. SEM observations of worn WC grains revealed that abrasion is an active wear mechanism during cutting. Complementary analysis by the electron backscatter diffraction (EBSD) technique revealed that worn WC grains are additionally characterized by significant strain which suggests the contribution of plastic deformation to the flank wear. Plastic deformation of WC is likely caused by high thermal and mechanical loads acting on the tool during machining.