Prediction of long-term strength of dissimilar welded joints

A calculational experimental technique for prediction of long-term strength of dissimilar welded joints (DWJ) operating under conditions of creep is proposed. The DWJ weaking due to the formation and development of low-strength decarburized interlayers in a fusion zone is taken into account along with some peculiarities of stressed state in heat-affected zone which are conditioned by the difference in creep speeds of welded metals and by the constrain of deformations of ''soft'' metal by ''hard'' metal in the fusion zone. The technique is based on short-term tests of DWJ on the long-term strength both as welded and after preliminary ageing to grow up interlayers. The data on the speed of decarburized interlayer growth in the fusion zone are also used. Test results of dissimilar contact butts of the 12Kh1MF and 12Kh18N12T steels are presented and processed as an example