Designing a gradient structure in a Ni-based superalloy to improve fretting fatigue resistance at elevated temperatures through an ultrasonic surface rolling process

Effect of Contact Stress and Slip Amplitude on the Fretting Fatigue Behaviour of Ultrasonic Surface Nanocrystallized Tc11 Titanium Alloy

“…By introducing compressive residual stress (CRS), work hardening layer and gradient refined microstructures, the surface mechanical properties are greatly improved to resist FF damage. After USRP, the surface layer is strengthened, the surface roughness is reduced and a gradient nanostructure is obtained [12,13]. It is essential to reveal the effect of contact parameters on fretting fatigue behaviour after the surface states are changed by USRP induced nanocrystallization.…”

“…In addition, the gradient nanostructure and surface work hardening introduced by USRP can hinder crack initiation by preventing the formation of permanent slip bands and changing the crack propagation direction. In addition, the reduced surface roughness and friction coefficient can reduce the tangential force on the contact surface and delay microcrack nucleation [13,20,21]. However, the dominant role of the strengthening factors may change under different loading conditions.…”