Study of Electrical Discharge Machining Parameters on Stainless Steel Using Copper Tool Electrode and Its Effect on the Structure and Electrochemical Properties

Abstract

In this work, the effect of the presence and the diffusion of the Copper from the tool electrode onto the EDMed stainless steel (SS) surface have been investigated by electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD), Quantometer analysis, and Optical microscopic observations. The Taguchi method was used to study the effects of Pulse-on time (t_on), Pulse-off time (t_off), discharge current (I), and overall machining time (τ) on chemical composition, microstructures, micro-cracks, and electrochemical corrosion of EDMed stainless steel workpieces. The results show that the variation of machining parameters changes the chemical composition of the workpieces. By increasing the discharge current and decreasing the Pulse-on time, the copper and the carbon diffuse onto the surface of the workpiece. Consequently, the chemical composition of the workpiece surface changes, which leads to an increment of the corrosion resistance. The XRD showed the formation of Fe₂C, Cr₃C_2, and CuNi. In addition, at higher values of discharge current and t_on/t_off ratio, the micro-cracks propagate on the surface of the workpiece.