Advances in the measurement and assessment of residual stresses in complex welded components

An important contributing factor to material degradation in many welded components is the presence of residual stress. Current structural integrity assessments of welded structures often lead to over-conservative estimates of minimum defect sizes. There is therefore a demand to provide more realistic residual stress profiles and improved methods to understand their impact on failure. There are therefore two themes to this paper; a review of advances in measurement methods and a summary of recent work that reappraises the treatment of residual stresses in integrity methods. There are many measurement methods but when it comes to practical complex welded components, of the type found in the nuclear industry, there are only a limited number of methods. These have been advanced principally to obtain more reliable measurements at greater depth. Typical examples are provided, together with an overview of recent findings from finite element simulations. The latter work illustrates that there is a significant problem of scatter between results. To provide more effective methods for including residual stresses in assessment methods it is shown, via recent work, that additional features of the welded structural system are required. These include information about the misfit that generates the residual stress field and how the structure responds as plasticity is created as a result of the interaction between residual and applied stresses.