Computational and experimental studies of high temperature crack initiation in the presence of residual stress

Residual stresses have been introduced into a notched compact tension specimen of a 347 weld material by mechanical compression. The required level of compressive load has previously been determined from finite-element studies. The residual stress in the vicinity of the notch root has been measured using neutron diffraction and the results compared with those obtained from finite-element analysis. The effect of stress redistribution due to creep has been examined and it is found that a significant reduction in stress is measured after 1000 h at 650° C. The implications of these results with regard to the development of damage in the specimen due to creep relaxation are examined.