Fretting behaviour of ion nitrided 34NiCrMo6 steel

The main objective of this study was to investigate the influence of ion nitriding surface treatment on fretting behaviour of 34 NiCrMo6 steel. Fretting tests were performed for this material, with treated and untreated surface, tested against AISI 52100 steel on an electromagnetic fretting machine. All experiments took place in air at controlled humidity and temperature using a plane-sphere contact geometry. In order to evaluate the effect of ion nitriding treatment, the fretting tests were done for both materials using an amplitude displacement ranging from 20 to 80 mum and a normal load of 20 N. The ion nitrided specimens have been tested on different humidity levels in order to study the effect of humidity on fretting behaviour. Friction force was acquired and measured during the tests. Fretting scars were observed by scanning electron microscopy and measured by profilometry for wear evaluation and to identify the mechanisms of surface failure.