Diamond Burnishing of Hard Turned Bainitic Components

Abstract

Bainitic steels are widely used in bearing systems for demanding applications such as wind turbines, where surface integrity plays a decisive role in fatigue resistance and service life. Hard turning as a productive finishing process may thermally affect the workpiece surface layer, particularly once initial tool wear sets in. Fine finishing processes might be needed to correct the detrimental effect on functional properties in these cases. In this study, the influence of hard turning and diamond burnishing on surface roughness, residual stresses, and near-surface microstructural modifications is investigated. The results demonstrate that diamond burnishing reduces surface roughness by approximately 80 % in terms of R _a and 78 % in terms of R _z , while simultaneously introducing high compressive residual stresses averaging 1200 MPa to depths of up to 160 μm. Importantly, no evidence of white etching layers was detected on initially hard-turned specimens, indicating that the process primarily modifies the residual stress state and surface topography without inducing detrimental thermal effects. These findings highlight the potential of diamond burnishing to improve the functional performance and service life of highly loaded power transmission parts.