Comparison of Neutron Diffraction Measurements of Residual Stress of Steel Butt Welds With Current Fitness-for-Purpose Assessments

In this research, the neutron diffraction technique was used to investigate the residual stress distributions in constrained carbon steel welds. Two full penetration welds were studied using (a) the stringer bead and (b) the temper bead weld techniques in 25 mm thick plate. The welds were not post-weld heat treated. The focus of the measurements is on the values of the subsurface and through-thickness strain/stress variation near the middle of the weld and the toe. The experimental results showed that both processes had high residual stresses particularly through the thickness. The measurements were compared with current fitness-for-purpose approaches, such as BS7910 and R6. It was found that the residual stress distribution in the temper bead welded specimen was not as favorable as suspected and post-weld heat treatment should be recommended to reduce residual tensile stresses in this type of steel welds.