Fretting Damage Evolution of Copper-Magnesium Alloy in Mixed Fretting Regime

The fretting damage evolution of copper-magnesium alloy in the mixed fretting regime was studied. Based on the characteristics of Ft-D-N curves and the morphologies of wear scars, the fretting running condition of the alloy was divided into a partial slip regime (PSR), mixed fretting regime (MFR), and gross slip regime (GSR). Fretting in the MFR not only leads to strong adhesive wear but also promotes the initiation and propagation of fatigue cracks, resulting in serious fatigue wear. The damage evolution of the alloy in the MFR includes four stages, namely, the initial shear deformation stage, adhesion and crack initiation stage, crack growth and fatigue wear stage, and final fatigue damage accumulation stage. The propagation and connection between the fatigue cracks at the stick–slip boundary and the microcracks in the subsurface plastic strain layer are the main reasons for the serious fatigue wear in the MFR.