Plasticity Effect on Residual Stresses Measurement Using Contour Method

Residual stresses have become an important player in the field of structural integrity for many years. Exact knowledge of residual stress distributions is essential in designing the engineering components as unexpected failures are inevitable wherever such stresses are ignored. There are many residual stresses measurement techniques including destructive and non-destructive ones. Among the mechanical strain relief (MSR) techniques, contour method is one of the youngest. Contour method relies on the material removal similar to other MSR techniques. In this method a part is carefully cut into two pieces along a flat plane, causing the residual stress normal to the cutting plane to relax. However, similar to other MSR techniques, plasticity can have a great influence on the accuracy of the results. In the present work, effect of plasticity on the residual stress measurement using contour method is investigated. Quenching is employed to induce residual stresses within the samples. To create different levels of plasticity, the samples were quenched at three different temperatures, 500°C, 700°C and 850°C. The residual stresses were then measured using contour method. Furthermore, the contour method procedure is simulated using finite element analysis to compare with the experimental results.