Influence of ultrasonic-assisted abrasive peening treatment on Ti-6Al-4V and OFHC Cu alloys

Numerous peening techniques exist can effectively modify the sample surface, although at the expense of severe surface damage and high capital investment. Ultrasonic-assisted abrasive peening (UAP) is a superior option that can peen the surface with minimal deterioration using a basic probe sonicator. In this paper, the influence of UAP parameters (i.e., beaker size and fluid volume, power, abrasive concentration, and time) on the surface integrity of Ti-6Al-4V and OFHC Cu was studied experimentally. The process is capable of inducing significant compressive residual stress at around 84 % and 280 % of yield strength in Ti-6Al-4V and OFHC Cu, respectively. The study examined the change in surface roughness (Delta R-a), Delta R-a = roughness before - roughness after peening. As peening intensities increase, Delta R-a reaches +7 nm, showing a surface finish in Ti-6Al-4V. The dislocations density calculated from the Williamson-Hall equation exhibited a 20 and 4.5-fold augmentation in peened Ti-6Al-4V and OFHC Cu in comparison to their un-peened state. EBSD analysis revealed a 28 % and 40 % reduction in grain size in Ti-6Al-4V and OFHC Cu after peening. This work validates the efficacy of the proposed UAP technique and supports the selection of optimized UAP process parameters.