MACHINABILITY AND MICROSTRUCTURE STABILITY DURING THE MACHINING OF PURE COPPER AND TITANIUM PROCESSED BY EQUAL CHANNEL ANGULAR PRESSING

For ultrafine grained materials (containing microstructures of 100-300 nm) to be manufactured and used in industry, machining research is needed to form and shape these materials into their final dimensions. Because of their high internal energy, UFG materials are known to have microstructures which are susceptible to undesirable changes at low temperatures. In this study, pure ultrafine grained copper and titanium as well as their respective coarse grained (CG) counterparts were tested for their relative machinability and microstructure stability through lathe turning. To evaluate the machinability cutting forces, tool wear, chip morphology, and surface roughness were studied using different cutting conditions. Tungsten carbide (WC) and polycrystalline diamond (PCD) cutting tools were utilized for turning the copper workpieces while only PCD was used for titanium. Microstructure stability was examined by measuring grain size and dislocation density using X-ray diffraction (XRD) techniques with some subsequent electron microscopy imaging