Electro-discharge Machining (EDM) of Superalloy Inconel 718 Using Triangular Cross-Sectioned Copper Tool Electrode: Emphasis on Topography and Metallurgical Characteristics of the EDMed Work Surface

Abstract

A case experimental research towards investigating aspects of electro-discharge machining on Inconel 718 superalloy using copper tool electrode (triangular cross section) has been delineated herein. Based on three controllable process variables, viz. peak discharge current, pulse duration and gap voltage, experiments have been carried out to investigate their effects on surface crack density and white layer thickness observed onto the top surface of the EDMed end product. Additionally, EDS analysis has been carried out to investigate the extent of carbon enrichment incurred onto the machined surface caused by pyrolysis of the dielectric media. XRD tests have been carried out to compare metallurgical features (various phases/precipitates present, extent of grain refinement, crystallite size and dislocation density) of the EDMed work surface with respect to as-received Inconel 718. Results, thus obtained, have also been compared to those of micro-indentation hardness test data.