Interaction between weld residualstresses and warm pre-stressing

Abstract: Cleavage fracture is a catastrophic phenomenon as it is a sudden structural collapse occurring to structures made of insufficiently ductile steels working at lower temperatures. In this study, the focus is on the material used in reactor pressure vessels (RPV) in nuclear power plants. The steel is exposed to radiation that by time causes embrittlement of the material. Safe operation of the power plant with today's engineering standards is possible by taking advantage of warm pre-stressing (WPS) effects. Welding is an inevitable part of manufacturing; therefore, it is important to investigate the influence of residual stresses (RS) due to welding on the load-bearing capacity of cracked components. Additionally, these stresses can also affect the benefits of WPS cycles which as mentioned earlier improves the structure behavior. In this study, the effects of two mechanisms in WPS on a RS field will be studied and compared. As the focus of the study is on the brittle fracture, a probabilistic model made by Kroon and Faleskog, will be used. To get an overview of the thesis, a summary of each topic will follow.