Experimental and numerical investigation on fretting fatigue behavior of Nickel-based single crystal superalloy at high temperature

The fretting fatigue behaviors of a nickel-based single crystal superalloy in contact with a powder metallurgy alloy at 600 degrees C are investigated. Fretting fatigue tests are conducted by using a novel high temperature fretting fatigue test apparatus that is developed, and the crystal plasticity finite element method is used to analyze the contact stress and activations of slip systems. The results show that the fretting conditions are partial slip regime for all loading conditions, and severe wear damage occurs across the slip region, which is accompanied by surface delamination and micro crack. Fretting fatigue cracks mainly initiate at the contact leading edge area, i.e., the stress concentration zone. The cracks grow along the (100) plane when multiple octahedral slip systems are activated simultaneously, or could be eliminated by wear. Considering the effects of both crystallographic slip and wear on the fretting fatigue damage, an improved fretting fatigue damage parameter, RA, is proposed to predict the fretting fatigue life. The predicted results agree well with the test results.