Low plasticity burnishing surface treatment: impact on surface integrity parameters of turned cylindrical Ti- 6Al-4V specimen

Surface integrity parameters are the major aspect in the extension of the fatigue life of aero- engine components. In this study, a modified burnishing surface treatment (low plasticity burnishing) with reduced cold work was proposed to improve surface integrity characteristics such as surface finish and hardness, and to induce stable, advantageous compressive residual stress in a cylindrical Ti-6Al-4 V specimen (as-received). In this process, a rolling rigid spherical tungsten carbide ball is pressed across a Ti-6Al-4 V specimen at an appropriate fluid pressure generated by the hydraulic unit. The low plasticity ball burnishing tooling system supported by a hydraulic unit of capacity 30 MPa is designed and developed in this study. By using a suitable specimen holding fixture, the ball burnishing with a small amount of plastic strain was carried out on the Ti-6Al-4 V cylindrical specimen. This research examined the effect of burnishing process variables namely tool pass and burnishing fluid pressure on compressive residual stresses, surface roughness, and hardness in Ti-6Al-4 V. The explicit dynamic analysis was carried out by using FE-Analysis software ABAQUS 6.17 as a part of numerical simulation. Hydraulic burnishing pressure and burnishing passes are the most influential parameters in generating favourable compressive residual stress, qualitative surface finish with less cold work in Ti-6Al-4 V turned specimen.