In-situ characterization and modeling of machining-induced residual stresses in peripheral milling of Ti–6Al–4V with rounded cutting edges

The residual stress state in the sub-surface of machined components can significantly impact the properties and performance of parts, such as tribological properties, fatigue life, and dimensional distortion. The evolution of residual stresses depends on the selected process parameters and tool geometry, which affect the thermo-mechanical load imposed on the workpiece. The cutting-edge radius is among the most important factors influencing the resulting residual stresses. In this paper, a semi-analytical model for the determination of residual stresses after peripheral milling of Ti–6Al–4V is presented. It considers the physical principles of orthogonal machining, including the complex geometric and kinematic relationships during milling, to enable the determination of the residual stress variation after three-dimensional milling. Model input parameters, such as the equivalent Hertzian width of contact, the contact pressure, and the friction coefficients, were determined using a dedicated in-situ experimental setup. In addition, digital image correlation (DIC) was used to characterize the displacement fields in the sub-surface during machining. After the peripheral milling of Ti–6Al–4V, the calculated residual stresses were compared with experimentally measured values for various process parameters and cutting-edge radii. The residual stress model reproduced the 3D residual stress depth profiles with acceptable accuracy. The maximum Root Mean Squared Error (RMSE) was 29.87 MPa.