Neutron Diffraction Analysis of Complete Residual Stress Tensors in Conventional and Rolled Gas Metal Arc Welds

Mitigation of residual stress in an arc weld by high-pressure rolling of the weld seam has been investigated using neutron diffraction. Rolling was found to greatly improve the residual stress distribution, causing significant compressive stresses at the weld line. A novel aspect of the data presented is that at each measurement location, normal strains in nine separate directions were evaluated, enabling calculation of the complete strain and stress tensors. It is thus confirmed that the principal stress directions generally lay close to the specimen coordinate axes (i.e. that they are well-aligned with the direction of welding and rolling), and that rolling does not cause any significant additional residual stresses which could have detrimental effects. Methods of uncertainty estimation and the applications of full-tensor residual stress measurements are also discussed.