Surface Integrity of C-40 Steel Processed with WC-Cu Powder Metallurgy Green Compact Tools in EDM

Electric discharge machining (EDM) is an electrothermal process where recast layer on the machined surface and heat-affected (HAZ) zone just below the machined surface are common phenomena. Thus, the assessment of surface integrity in EDM is a very important task. In this study, an attempt was made to modify the surface integrity of C-40 steel in EDM. WC-Cu powder metallurgy (P/M) green compact tools were used so that the tool material could be transferred to the work surface and thereby the surface characteristics could be altered. WC was used as tool material because of its ability to produce a hard layer over the work surface. A detailed experimental study was performed. The effect of various process parameters on the surface characteristics were presented with the support of analyses such as material transfer rate (MTR), tool wear rate (TWR), surface roughness, optical microscopy, scanning electron microscopy (SEM), energy dispersive x-ray (EDX), x-ray diffraction (XRD), microhardness testing, etc. It was established that the surface integrity of the workpiece changes with the desired deposition of a hard composite layer of WC and copper over the work surface.