Investigation on residual stress induced by multiple EDM discharges

Abstract The thermal removal mechanism of electrical discharge machining (EDM) process leads to modifications of the rim zone. One of these modifications is tensile residual stress. This tensile stress reduces the mechanical load that can be tolerated in the final part application. Hence, it is important to know the resulting residual stress depending on the induced thermal loading by EDM. In this work, the residual stress is simulated based on the resulting temperature field generated by the EDM discharges. The predictions are based on a solution of the heat conduction equations taking into account the material removal, where the heat flux into the work piece is calibrated by measurement data. The tensile residual stress is then determined by using a reduced order model for the temperature boundary condition in the heat treatment simulation software SysWeld®. In the first step, a single discharge is investigated, subsequently the methods are applied to predict the tensile stress for multiple discharges. The simulation results are compared to the residual stress measured in specimen for single and multiple discharge experiments using X-ray diffraction.