Cross-sectional mapping of residual stresses in a VPPA weld using the contour method

We present measurements of the cross-sectional residual stress profile in a 2024 aluminium alloy VPPA weld using a newly invented technique - the contour method. The method is destructive, but simple in principle and easy in use. It needs only one straight cut through a sample on the plane of interest, followed by measurement of the surface contour produced by relaxation of the pre-existing stress field. Finite-element modelling is then used to back-calculate the original stress field. In this case we validate measurements made with the contour method, by using non-destructive diffraction data obtained from the same weld before cutting. This allows a comparison to be made and excellent agreement between the results from the two methods is seen. The study indicates that the contour method is a powerful novel technique to obtain an accurate full two-dimensional map of residual stress fields.