Improvement of mechanical and tribological properties of steel and grey cast iron camshafts with plasma nitriding

The surface camshafts exposed to severe stresses and abrasive forces than are the interiors parts. As severe forces reach the limits of cam material's resistance, wear starts at the surface of the material. For these reasons, surface properties of materials which are subjected to such type effects should be improved. Plasma nitriding is a process used advanced surface modification techniques to solve these type problems. In this study, it is aimed to increase the camshaft materials lifetime with performing plasma nitriding process on 31CrMoV9 nitriding steels and gray cast irons used as material for the camshaft manufacturing to improve mechanical and tribological properties. Structural, mechanical and tribological properties of the materials subjected to plasma nitriding with various process parameters were examined with XRD, SEM, 3D non-contact profilometer, microhardness, fatigue and pin-disc wear devices. Also, fatigue test results was compared with finite element analysis results and finite element analysis of nitrided steel and casting camshafts were analysed. Best results were obtained from plasma nitriding performed at low nitrogen content in the gas mixture and in high time periods.