Evaluation of residual stress relaxation in electron-beam welded stainless steel under in-situ cyclic loading using Bragg edge imaging

Welding processes are known to generate residual stresses which might affect the fatigue performance of components. Residual stresses interact with the applied load, and studies have shown that when the static or cyclic yield strength is exceeded, local plastic deformation might occur and subsequently reduce the residual stresses. The omission of stress relaxation information in power plant component assessment procedures can lead to over-conservative life-time predictions of power plant components. More accurate information of residual stress relaxation will lead to more realistic lifetime predictions and possible lifetime extension. We propose an in-situ cyclic test in conjunction with Bragg edge imaging on IMAT which will allow mapping residual strain profiles in one exposure, thus enabling tracking the evolution of residual strains at different regions across the weld.