Tailoring surface morphology and integrity of Inconel 718 using reciprocating Mo-wire and different discharge energy levels of WED-machining

The precipitation-hardenable Inconel 718 alloy offers difficulties with the material subtractive action of the cutting tools during conventional machining processes. In this relation, the non-conventional wire electrical discharge-machining (WEDM) process has been proven to be promising to process such difficult-to-be-machined materials due to its material removal nature (via thermoelectric phenomenon) that does not depend on the material’s mechanical properties. This work aimed to evaluate the effect of three discharge energies, measuring three-dimensional morphology and surface texture volumetric parameters, using deionized water (H 2 O-De) and emulsion hydrocarbon (HC8%) as dielectric fluids and a molybdenum wire electrode. An experimental methodology is used by employing a focus-variation microscope to quantify the peaks and valleys resulting from the recast layer, correlating with amplitude and functional parameters to the thermal effect resulting from the discharge. The results showed that the type of dielectric medium influenced the recast layer thickness of the Inconel 718 workpiece surfaces. Also, the amplitude of the mean surface roughness (Sa) showed higher deviations when the discharge energy was increased for both dielectrics (HC8% and H 2 O-De). Furthermore, it was observed that the HC8% dielectric produced smaller chemical modifications of the recast layer than that of the H 2 O-De fluid. In addition, the thermal phenomenon promoted by the electrical discharge was found to foster the formation of a passive and protective layer of MoO 3 when H 2 O-De dielectric was applied.