Modélisation du comportement en plasticité et à rupture des aciers bainitiques irradiés

Abstract : Low alloy steels are used in various equipments of nuclear reactors. Subjected to neutron irradiation produced during the operation of reactors, these materials exhibit significant changes in their microstructure, especially with the formation of radiation defects as interstitial loops, void clusters and precipitates. These defects in interactions with dislocations lead to a hardening and embrittlement which are directly related to the received dose and neutron flux. The plastic behaviour of non-irradiated low alloy bainitic steels has been the object of several modellings based on observations from experiments and atomistic simulations. Some of them result from thesis supported by EDF and CEA, which describe different strategies for the micromechanical modelling of brittle failure. Improvements in this work come from the integration of new physical characteristics and the attention paid to the representativity of the microstructure: whereas realistic microstructures in terms of morphology and crystal orientations have been adopted, a dislocation density based constitutive model in the large deformation framework is used to describe crystal plasticity. This choice is justified by the need to take into account, in the constitutive modelling, the interactions between dislocations and irradiation defects under severe loading conditions. The plasticity laws have been implemented in the finite elements code ZéBuLoN in order to perform computations of polycrystalline aggregates. Such aggregates are representative volume elements. They thus provide the database required for the application of brittle failure models to structures. This multiscale character confers to the modelling the status of “micromechanical local approach of failure”
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Mechanics. École Nationale Supérieure des Mines de Paris, 2010. French


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Submitted on : Thursday, April 1, 2010 - 5:44:55 PM
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Can Ngon Nguyen. Modélisation du comportement en plasticité et à rupture des aciers bainitiques irradiés. Mechanics. École Nationale Supérieure des Mines de Paris, 2010. French. <tel-00469582>

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