In-situ SEM study of short fatigue crack propagation behavior in a dissimilar metal welded joint of nuclear power plant |
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| Affiliation: | 1. AML, School of Aerospace Engineering, Tsinghua University, Beijing 100084, China;2. CPI Nuclear Power Institute, 18 Xizhimen St., Beijing 100044, China;3. Suzhou Nuclear Power Research Institute, Suzhou 215004, China;1. National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, USA;2. National Institute of Standards and Technology, 100 Bureau Dr, Gaithersburg, MD 20899, USA;3. Brazilian Nanotechnology National Laboratory, Caixa Postal 6192, Campinas, SP 13083-970, Brazil;1. Material Research Centre, College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea SA1 8EN, UK;2. Airbus Defence and Space, 81663 Munich, Germany;3. Airbus Group Innovations, 81663 Munich, Germany |
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| Abstract: | In-situ Scanning Electron Microscopy (SEM) fatigue experiments were carried out to study short fatigue crack propagation (FCP) behavior of various regions (weld zone, interface region and heat affected zone (HAZ)) in a domestic dissimilar metal welded joint of nuclear power plant. The local microstructural effect on short fatigue crack initiation and propagation behavior was investigated with its influence on both material fatigue and structure fatigue analyzed. Considering material fatigue, in the weld region, crack grows along δ ferrites when propagating parallel to the dendrite, and deflects or branches along δ ferrite, γ austenite dendrite, δ/γ interface and grain boundaries when propagating perpendicular to the dendrite; in safe ends, the crack grows along slip lines and coalesces with secondary cracks; in A508 HAZ, the crack propagates or branches along martensite transgranularly. In terms of structural fatigue, the crack tends to deflect when propagating across the weld/A508 interface or weld/316 L interface with the influence of local microstructure, and the weld/A508 interface region has a resistance to FCP due to its high strength. The fatigue crack propagation rate of each region was compared and analyzed. The fatigue fractography was also characterized under SEM to analyze the crack propagation process. |
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