Enhancing Electrical Discharge Machining Performance by Mixing Nano Chromium Trioxide Powder with Soybean Dielectric to Machine Inconel 718 Alloy

Abstract

Inconel 718 super alloy is suitable for components exposed to high temperatures and demanding high strength; it is one of the hardest alloys to machine by conventional processes due to its properties. Nano Powder mixed electrical discharge machining is one of the most sophisticated processes to produce precise three dimensional complicated forms of hard metals through a thermo-physical process, so it is suitable for machining Inconel 718. This study reports an experimental investigation to improve the machining performance of Inconel 718 super alloy by adding nano chromium oxide powder particles to biodegradable and renewable soybean oil, which is used as a dielectric fluid to preserve the environment, with a magnetic field to assist in improving the process performance. The effects of machining parameters, namely peak current, pulse on time, powder concentration, and magnetic field on the responses in terms of white layer thickness, heat affected zone, surface roughness, material removal rate, and surface crack density were investigated. The observed results manifested that the addition of nano chromium oxide particles to dielectric fluid enhances the process performance. The white layer thickness and heat affected zone improved by 43.93% and 48.82%, respectively. The enhancements in measured surface roughness and material removal rate were 51.76% and 20.62%, respectively. Micrographs of scanning electron microscope verifies that the number of cracks on the machined surface with 4 g/l of nano Cr 2 O 3 powder addition was reduced by half, and surface crack density improved by 10.31%, in comparison to machining without powder addition. It is observed that the current had the largest effect on the responses, followed by powder concentration, pulse on time, and magnetic field.