Residual Stress Regenerated on Low Plasticity Burnished Inconel 718 Surface After Initial Turning Process

Low plasticity burnishing (LPB) has been extensively employed in aero-industry to enhance fatigue performance of machined components by introducing compressive residual stress. Effects of various parameters on the residual stress field induced by low plasticity burnishing have been investigated by many researchers. However, initial residual stresses induced by machining are one of the important factors which affect the residual stress regenerated by the LPB process. The present work aims to develop an analytical model which takes into account the initial residual stress and burnishing parameters to predict residual stress field of workpiece material Inconel 718 based on Hertz contact theory and elastic–plastic theory. Initial residual stress fields were produced by turning of Inconel 718 and were measured by using X-ray diffraction technique. Two types of material constitutive models such as the linear hardening model and isotropic–kinematic model were employed to describe the elastic–plastic behavior of workpiece material Inconel 718. An analytical study was performed to analyze the effect of the initial residual stress field and burnishing parameters on residual stress induced by low plastic burnishing. The results of analytical model were verified by conducting the LPB experiments on initial turned Inconel 718. The results showed that the shape and magnitude of the residual stress field obtained with considering the effect of initial residual stress field was in good accordance with experimental measurements.