Improvement of surface integrity of Nimonic C 263 super alloy produced by WEDM through various post-processing techniques

Wire electrical discharge machining (WEDM) process provides a cost effective solution to generate complicated shapes in various exotic materials, irrespective of their hardness. However, WEDM process removes the material by thermal erosion mechanism which in term affects the topography and mechanical characteristics of the material. In view of this, an effort is needed to eliminate the adverse effect of WEDM process on the final product surface. Therefore, the present work evaluates surface morphology, surface roughness, elemental composition, micro-hardness and residual stress of the machined surface produced by various WEDM strategies such as, rough cut and finish cut. Two post-processing techniques namely, grinding and etching-grinding are proposed to remove recast layer and also to improve the surface integrity of the machined surface. The proposed strategy found to be an efficient post-processing technique for complete removal of recast layer and generation of surface with an average surface roughness as low as 0.024 mu m, high compressive residual stress as high as 500 MPa and basic elemental composition. The basic mechanism of these process are also explained in details.