Study of the fatigue behaviour of dissimilar metal welds

摘要

In nuclear power plants, many dissimilar metal welds are located in the primary circuit joining the ferritic components to the stainless tubes. Dye penetrant tests on the outer surface of dissimilar metal welds show defects near the interface ferritic alloy/309L stainless steel. They are mainly due to grain boundary de-cohesions and are located in the weld metal when the structure is austenitic. Our work aimed at identifying the critical parameters governing the failures mechanisms. Our hypothesis of failures mechanisms is based on failures due to thermal solicitations during start up and shut down procedures. We simulated the thermal fatigue by cyclic deformation tests at 593 K. (authors). 3 refs.