Surface Morphology Analysis of Inconel 625 through Multi-walled Carbon Nanotubes-Based Electric Discharge Machining

This study explores the surface behavior of Inconel 625 (IN 625) workpieces machined using electric discharge machining (EDM). Multi-walled carbon nanotubes (MWCNTs) are efficiently dispersed in a hydrocarbon-based dielectric fluid prior to machining, and this prepared fluid is employed during the IN 625 machining process. While keeping pulse-on-time, discharge current, and duty cycle constant, variations in MWCNTs powder ratio are introduced. The investigation focuses on material removal rate (MRR), surface roughness, and surface morphology with different nanopowder ratios. Optimal results are achieved at a concentration of 1 g/L., which results in higher MRR and minimal TWR & SR at specific process parameters, i.e., Is = 21 A, Ton = 15 mu s, DC = 20%. The findings reveal that the addition of nanopowder to the dielectric fluid leads to improved MRR, surface roughness, and surface morphology compared to conventional dielectric fluid FESEM, EDS, and AFM analysis, showing improved surface morphology in MWCNTs-based EDM-processed samples compared to EDM oil-treated ones, with reduced cracks, craters, and suspended particles. Microhardness of EDM-processed parts with MWCNTs ranged from 385 to 575 HV, showing an increase compared to the parent IN 625. The study enhances our understanding of how manipulating nanopowder ratios in the dielectric fluid positively impacts the machining performance and surface characteristics of IN 625 during EDM processes.