Analysis of the Surface Integrity when Nitriding AISI 4140 Steel by the Sink Electrical Discharge Machining (EDM) Process

The aim of this this work is to demonstrate the feasibility of nitriding AISI 4140 steel using electric discharges produced by sink EDM equipment. This was performed using a copper electrode, and mixed deionized water and urea as the dielectric fluid. Techniques such as laser profilometry, x-ray diffraction (XRD), glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM) and optical microscopy were employed. The proposed mechanism for this particular nitriding process was that of ion implantation and the layer under scrutiny was shown to have been hardened, however coming to beneath of the surface the hardness decreases, which coincides with the impoverishment of the quantity of nitrogen inserted.