Plasma nitriding of 90CrMoV8 tool steel for the enhancement of hardness and corrosion resistance

The aim of the study is to apply a plasma nitriding process to the 90CrMoV8 steel commonly employed in wood machining, and to determine its efficiency to improve both mechanical and electrochemical properties of the surface. Treatments were performed at a constant N(2):H(2) gas mixture and by varying the temperature and process duration. The structural and morphological properties of nitrided layers were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with EDS microanalyses. Surface hardening and hardness profiles were evaluated by micro hardness measurements. To simulate the wood machining conditions, electrochemical tests were carried out with an oak wood electrolyte with the purpose of understanding the effects of the nitriding treatment on the corrosion resistance of the tool in operation.