Enhanced rolling contact fatigue behavior of selective electron beam melted Ti6Al4V using the ultrasonic surface rolling process

This paper investigates the influence of building directions and ultrasonic surface rolling processing (USRP) on rolling contact fatigue (RCF) performances of selective electron beam melted Ti6Al4V. Results show the RCF performance in the xoz direction is 54% higher than that of the xoy direction due to the poor crack propagation resistance of the prior-β columnar grain boundary α layer. The USRP treated samples show ∼ 30% longer RCF life than that of untreated samples. The increased RCF performance is attributed to large work hardening, surface nano-crystallization, surface residual compressive stress, and the changed lubrication condition from boundary lubrication to mixed lubrication, which suppresses crack initiation and propagation.