A study on the effect of plasticity on the measurement of residual stresses using ultrasound technique

Abstract

Residual stresses can have detrimental effect on the life cycle of engineering components and can affect the accuracy of the fatigue life prediction models. Accurate measurement of these stresses are therefore crucial. . However, destructive and semi-destructive methods of measuring residual stresses often cause damage to the components. In contrast, the non-destructive ultrasonic method allows for intact measurement of residual stresses even, in situation where portability is not feasible. Various waves can be utilized in the ultrasonic method for measuring residual stresses. In this study, longitudinal critically refracted (LCR) waves were employed due to their higher sensitivity, larger scanning area, and lower sensitivity to texture effect, making them preferable over other waves. The purpose of this study was to investigate the influence of plasticity on the measurement of residual stresses using the ultrasonic method. To achieve this, two stainless steel disks were subjected to quenching at temperatures of 300 °C and 700 °C to induce different levels of residual stresses and plasticity. The material properties of the disks were determined through standard tensile tests to facilitate numerical simulations. Tensile test specimens were extracted from the initial sheet to measure the yield stress and modulus of elasticity. The coefficient of acoustoelasticity, was determined by subjecting the tensile test specimens to different stress levels and recording the wave flight time. The coefficient of acoustoelasticity for stainless steel 316Lwas obtained using the slope of and (E(t-t0))/t0,. Residual stresses were experimentally measured using both the ultrasonic method and the center-hole drilling method, and the results were compared with those obtained from numerical analyses. The findings from center-hole drilling method, ultrasonic method, and numerical simulation were then compared and discussed. Different levels of plasticity were considered, and the accuracy of measuring residual stresses was analyzed and evaluated.