Residual stress prediction of micro-milling Inconel 718 thin-walled parts

Surface residual stress is generated during the micro-milling thin-walled parts of nickel-based superalloy Inconel 718. Because of the low rigidity, deflection of thin-walled parts is easy to occur under residual stress, which makes it difficult to ensure the dimensional accuracy of thin-walled parts. Additionally, the performance of thin-walled parts is directly impacted by the residual stress state. At present, the research on the prediction of residual stress in micro-milling thin-walled parts is still blank. In this paper, the Inconel 718 mesoscopic thin-walled parts are taken as the machining objects. Firstly, a simulation model of micro-milling thin-walled parts process is established by using the finite element program ABAQUS, which realizes the prediction of residual stress in micro-milling thin-walled parts based on process simulation. And the validity of the prediction results of residual stress is verified by XRD experiments. Then, a four-factor and three-level L9 orthogonal simulation experiment is designed, which uses spindle speed, feed per tooth, axial cutting depth, and radial cutting depth as influencing factors. The prediction model of surface residual stress of Inconel 718 micro-milling thin-walled parts is built based on the results of orthogonal simulation experiments. And the model is verified by variance test and experimental validation. Finally, the optimization of cutting parameters for micro-milling Inconel 718 thin-walled parts is achieved with the maximum residual compressive stress as the optimization objective.