The subsurface damage mechanism of Inconel 690 during fretting wear in pure water

The subsurface damage mechanisms of Inconel 690 induced by fretting wear in pure water were investigated. The results showed that the major damage mechanism were oxidation, deformation, fatigue and delamination cracks in worn subsurface. Due to the low oxygen concentration in pure water, preferential oxidation of Cr occurred and plugged into tribologically transformed structure (TTS) at the interface of wear debris layer (WDL)/TTS, which produced complex structures of Cr-rich oxide zone surrounded by Ni-rich zone in TTS. Continued oxidation led to spread of Cr-rich oxide zone, accompanying with formation of WDL consisting of nano-sized oxides and Ni-based grains, however such a spread was limited by the TTS/general deformed layer (GDL) interface, and did not extend to GDL.