Contemporary approaches to reducing weld induced residual stress

Self-equilibrating residual stresses may occur in materials in the absence of external loading due to internal strain inhomogeneity. While favourable distributions of residual stress can bestow an object with the appearance of superior material properties, most welding processes leave behind residual stresses in particularly unfavourable patterns, causing a greater susceptibility to fracture based failure mechanisms and unintended deformation. Currently, heat treatment is the primary means of removing these stresses, but since the formation of residual stress is dependent upon many material and process factors, there are several other viable mechanisms (using thermal, mechanical or phase transformation effects) by which it may be modified. It is only now, using relevant advances in numerical and experimental methods, that these techniques are being fully explored. This article gives a brief introduction to weld induced residual stresses and reviews the current state of the art with regard to their reduction. Emphasis is placed on the recent development of unconventional techniques, and the mechanisms by which they act.