Prédiction de la non-rupture fragile dans un joint soudé en acier C-Mn dans le domaine de la transition fragile/ductile

Abstract : This work concerns the nuclear safety, specifically the secondary circuit integrity of pressurized water reactors (PWR). Therefore, the present study focuses on the fracture behaviour of welded thin structures in brittle/ductile transition. It aims at developing the threshold stress model initially proposed by Chapuliot, to predict the non-brittle-fracture of this welded structure. The model is identified for the welded joint in C-Mn steel for nuclear construction, specifically in the upper part of the transition.A threshold stress, below which the cleavage cannot take place, is identified using tensile tests at low temperature on axis-symmetrical notched specimens taken in welded joint. This threshold stress is used to define the threshold volume where the maximum principal stress exceeds the threshold stress during the test.The analysis by SEM of specimen fracture surfaces shows that the gross solidification molten zone in the weld is the most likely to cleave. The relation between the brittle fracture probability and the threshold volume in the gross solidification molten zone is established via a sensitivity function, using multi-materials simulations. The model thus identified is tested for the prediction of non-brittle-fracture of SENT specimens taken in the welded joint and tested in tension. The results obtained are encouraging with regards to the transferability of the model to the actual structure
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Other. Ecole Centrale de Lille, 2009. French. <NNT : 2009ECLI0017>


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Thai Ha Nguyen. Prédiction de la non-rupture fragile dans un joint soudé en acier C-Mn dans le domaine de la transition fragile/ductile. Other. Ecole Centrale de Lille, 2009. French. <NNT : 2009ECLI0017>. <tel-00578811>

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