A New Cutting Strategy to Reduce Plasticity Errors in Measuring Welding Residual Stress via the Contour Method

The Contour Method is a well-established destructive technique for determining cross-sectional maps of residual stress in manufactured metallic components. The validity of the technique is dependent on linear elastic relaxation of residual strains across the plane of interest as the component is progressively cut into two parts across the plane of interest. However, for some welded components, redistribution of the residual stress field during the contour cutting step can result in local plastic deformation of the cut faces, giving errors in the measured residual stress map. This article describes a novel implementation of the Contour Method for welded components that can mitigate the risk of introducing such strain relief errors in the measured residual stress field. An orthogonal cutting sequence is applied where the component is first cut along the weld centreline (in the longitudinal direction) into two mirror-symmetric halves. Each one-half component is then cut transversely towards the weld line at mid-length. The out-of-plane deformation contours of the four cut faces are then measured, and the original residual stresses present on each cut section are determined using the multiple cut contour method. The efficacy of implementing the new contour measurement approach to fusion-line weldments is demonstrated both numerically and experimentally.