The damage mechanism of Alloy 690TT against Alloy 600 caused by fretting wear in room temperature pure water

The damage mechanism of Alloy 690TT against Alloy 600 induced by fretting wear in room temperature pure water was investigated. Detail characterization was performed for the microstructure evolution and the cracks by using transmission electron microscopy. The results indicated that the fretting wear mechanism was a combination of abrasive wear, delamination and severe plastic deformation down to nanostructures. Intergranular oxidation along the nanograin boundaries and internal oxidation in the subsurface caused the crack initiation and propagation. The dislocation interactions during the severe plastic deformation and the interaction between oxidation and amorphization were responsible for the formation of the nano-voids. Amorphization was caused by the joint action of further plastic deformation and oxidation of the nanostructures, resulting in the acceleration of the crack propagation.