Validation of neutron diffraction and the incremental deep hole drilling residual stress measurements of a high strength T butt weld test piece using the contour residual stress measurement technique

Off shore ring stiffened cylindrical structures are subjected to high stresses caused by static or variable external hydrostatic pressure and residual stresses due to the fabrication and welding processes. The use of numerical simulation allows a straightforward calculation of the stresses induced by the hydrostatic pressure in the structure. However it is more intricate to determine the residual stresses resulting from the progressive manufacture of components and assembly using a multi-pass welding processes. This paper presents the work carried out to ascertain the residual stresses present within a high strength welded T-plate test piece, representative of part of a ring stiffened cylindrical structure, by the contour method to determine the longitudinal residual stresses across the width of the test piece. This test piece had previously been subjected to neutron strain scanning in a pattern across the test piece and also the incremental Deep Hole Drilling (iDHD) and, the Deep Hole Drilling (DHD) processes to validate the neutron results for the longitudinal and transverse components of residual stress in the weld toe and centreline of the T butt weld. Therefore the work on this test piece is unique as three methods of residual stress measurement have been used. The results of these measurements are presented and compared to highlight agreements and discrepancies in the measured residual stresses by each method. (author)