Assessment of Weld Residual Stress Measurement Precision: Mock-Up Design and Results for the Contour Method

Recent experimental work has shown residual stress measurements in welded material to be difficult. To better assess the precision of residual stress measurement techniques, a measurement article was designed to allow repeated measurements of a nominally identical stress field. The measurement article is a long 316L stainless steel plate containing a machine-controlled eight-pass slot weld. Measurements of weld direction residual stress made with the contour method found high tensile stress in the weld and heat-affected zone, with a maximum near 450 MPa and compressive stress away from the weld, a typical residual stress profile for constrained welds. The repeatability standard deviation of repeated contour method residual stress measurements was found to be less than 20 MPa at most spatial locations away from the boundaries of the plate. The repeatability data in the weld are consistent with those from a previous repeatability experiment using the contour method in quenched aluminum bars. A finite-element simulation and neutron diffraction measurements were performed for the same weld and provided results consistent with the contour method measurements. Much of the material used in the work remains available for use in assessing other residual stress measurement techniques, or for an interlaboratory reproducibility study of the contour method.