Surface rolling deformed severity-dependent fatigue mechanism of Ti-6Al-4V alloy

• Surface rolling deformed severity-dependent fatigue mechanism of titanium alloy was revealed. • The microstructural evolutions of the samples with different surface rolling deformation severities during fatigue loading were revealed. • The residual stress evolutions during fatigue loading for the different surface rolling deformed samples were clarified. • A surface strengthening strategy was given to enhance the stress-controlled fatigue property of titanium alloy. This work investigates the effect of initial surface plastic deformation on the fatigue behavior of Ti-6Al-4V alloy based on the microstructure and residual stress evolution under fatigue loading. The high strain hardening ability, full play of compressive residual stress, and excellent surface integrity of samples with low plastic deformation severity resulted in relatively higher fatigue strength. Microstructural analysis revealed that the ultrasonic surface rolling process (USRP) applied to samples with low plastic deformation severity accommodated plastic strain by refining the grains, whereas the grains coarsened in the USRP samples with high plastic deformation severity for accommodating the plastic strain.