A response surface function method to characterize residual stress and cumulative plastic strain through indentation

Abstract

Shot peening is a mechanical surface treatment used to improve the material fatigue performance by introducing compressive residual stress and work hardening. In order to characterize the residual stress (RS) and cumulative plastic strain (PS) of the treated surface simultaneously using the instrumented indentation technique, a Response Surface Function method is proposed in this work using a calibration by finite element simulations. The method is first verified numerically, and the results indicate that the determined values can accurately represent the input values, which shows the possibility of experimental application. The proposed method is then applied experimentally on a nickel-based alloy, Inconel 625. For validation, the solved profiles are compared with the profiles measured by X-ray diffraction (XRD). Although there is a difference between the profiles obtained by these two measurement techniques, the proposed method makes an advance on the characterization of residual stress and cumulative plastic strain simultaneously. It has demonstrated its feasibility, indicating its potential for practical application.