Surface quality investigation in surfactant-based EDM of Inconel 617 using deep cryogenically treated electrodes

Surface quality governs the physical, mechanical, tribological, physio-chemical, and biological properties of materials. Considering the excellent mechanical characteristics of Inconel 617 and the nature of its intended applications, electric discharge machining is generally engaged. However, there is still a need to uplift the surface quality of machined parts to improve their working life and performance. Therefore, this study revealed the potential of deep cryogenically treated (DCT) electrodes under dielectrics modified with span and tween in the said context using a full factorial experimental design. Experimental findings are deeply investigated by employing 3D surface profilometry, scanning electron, and optical microscopy. Cryogenically treated electrode(s) have demonstrated a better surface quality in comparison to the non-treated electrodes, such as DCT Cu has provided a 25.5% lower roughness value than non-treated Cu. Referring to the role of additives, there exists a reduction of 32.5% in roughness when DCT brass is used instead of typical brass using a mixture of span-20 (S-20) and kerosene as a dielectric. The surface finish given by the cryogenically treated brass is 18.99% better when compared to the average value given by all cryogenically treated electrodes considered in this study. It has also been revealed that tween-based dielectrics gave 83% better surface finish than span-based dielectrics with DCT electrodes.