An experimental investigation of surface modification of C-40 steel using W–Cu powder metallurgy sintered compact tools in EDM

Abstract

Surface modification is essential to enhance the surface properties of engineering components. This may be accomplished either in the form of altering the surface chemistry or by providing a protective layer over the work surface. In this paper, the surface modification phenomenon by depositing a protective layer over the work surface by electrical discharge machining (EDM) is presented. The potential of EDM, which is otherwise a useful non-conventional machining process, has been explored for surface alteration by depositing material over work surface using tungsten–copper (W–Cu) sintered powder metallurgy tools. The photographic presentation of the EDMed surface at different parameter settings is given. The variations of mass transfer rate (MTR), deposited layer thickness (LT), and average surface roughness (R a) with various parameter combinations are presented in graphical form and their effects are discussed. A wide spectrum of MTR ranging from nearly 1 to 191 mg/min and average surface roughness values ranging from 3 to 15 μm have been achieved. A wide range of deposited layers with thickness varying from 3 to 785 μm has been achieved by various combinations of process parameters. The microstructure of the deposited layers with microhardness at different zones is presented. It has been observed that the microhardness is gradually increasing from the base material to the deposited layer and its maximum value is found to be 15.7 GPa at the hardest zone. SEM, EDX, and XRD analyses has been also performed for further characterization of the deposited layer. A quantitative analysis of the layer has been carried out by EDX and it is found that the inner part of the layer is richer in tungsten than the superficial surface. This contributed towards the higher hardness of the layer at the core.