Surface Modification of Chromium–Nickel Steel by Electrolytic Plasma Nitriding Method

Electrolytic plasma nitriding is an attractive chemical heat treatment used to improve the surface properties of steel by implementing nitrogen saturation. This method is widely applied to steel and iron-based alloys operating under various operating conditions. In this work, using liquid-phase plasma nitriding technology, a nitrided layer was obtained on the surface of 40CrNi steel in electrolytes of different concentrations. The microstructure and phase composition of the nitrided layer were investigated and analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), and we performed Vickers hardness and wear resistance tests using the ball-on-disc method. The microhardness and wear resistance of nitrided 40CrNi steel were significantly improved due to the lubricating properties of the ε-Fe2N phase formed on its surface.