Studies on the surface characteristics of Ti60 alloy induced by turning combined with ball burnishing

Abstract

Ball burnishing can enhance the service performance of parts and is more and more widely used in industrial production. To reveal the formation mechanism of the surface characteristics of ball burnishing of Ti60 alloy, the turning combining ball burnishing experiment was carried out, and the surface characteristics, such as surface morphology, roughness, residual stress, microhardness, and microstructure were investigated in detail. The results show that the surface roughness ranges from 63.9 nm to 110.3 nm and the height difference of the surface roughness profile is within 600 nm after burnishing. The stress concentration factors after burnishing change between 1.06 and 1.204. There is a positive correlation between the stress concentration factor and the surface roughness. The sinusoidal decay function is an effective method to predict the distribution of residual stress along the depth. After burnishing, the micro-hardness distribution shows a trend of first increasing and then decreasing. In addition, the second α phase (αs) and β phase are observed to be deflected obviously after burnishing. The kernel average misorientation (KAM) indicates that significant plastic deformation occurs in the surface layer after burnishing. The average values of local misorientation before and after burnishing are 0.52° and 0.69° respectively. The geometrically dislocation density increases from 7.02 × 109 mm−2 to 9.31 × 109 mm−2. The grain size is reduced from 13.1 μm to 10.5 μm, and the proportion of low-angle grain boundaries (LAGBs) has increased from 12.7% to 22.5%. Intragranular deformation increases significantly and texture exists after burnishing. The research methods and conclusions can provide technical and data support for better burnishing effect of Ti60 alloy.