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Etude de la durée de vie et de l'endommagement intergranulaire par fatigue des métaux cubiques à faces centrées : influence de la taille de grains et de l'épaisseur d'éprouvette

Abstract : Understanding and predicting the fatigue damage is a major issue in the design of the sodium-gas heat exchanger of the next generation of nuclear reactors.Cyclic tests were carried out on 316L SS specimens with different thicknesses, for two very different grain sizes, in order to quantify the influence of these parameters on the fatigue lifetime. Then, cyclic tests interrupted by microscopy observations (SEM) allowed the understanding of the early stages of fatigue damage induced by a large grain size specimen. Finite element simulations of the cyclic deformation of crystalline aggregates were performed with the Cast3M software. The localization of plasticity in the form of persistent slip bands (PSBs) is considered. The increase of the vacancy concentration in the PSBs, leading to their dilatation is introduced. Predictions of the PSB extrusion through impinged GBs and of the associated stress fields were studied. All these predictions, coupled with two damage models, made possible to predict the number of cycles to intergranular microcrack initiation. Finally, comparisons between experimental measurements and predictions of (i) the PSB extrusion through GBs and (ii) the number of cycles to microcrack initiation are made. The effects of material, nature of GBs and loading conditions on fatigue crack initiation mechanisms are finally discussed.
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https://tel.archives-ouvertes.fr/tel-03349927
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Submitted on : Tuesday, September 21, 2021 - 1:01:47 AM
Last modification on : Wednesday, September 22, 2021 - 3:36:08 AM

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HAZAN_Jerome_2019.pdf
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  • HAL Id : tel-03349927, version 1

Citation

Jérôme Hazan. Etude de la durée de vie et de l'endommagement intergranulaire par fatigue des métaux cubiques à faces centrées : influence de la taille de grains et de l'épaisseur d'éprouvette. Mécanique des solides [physics.class-ph]. Sorbonne Université, 2019. Français. ⟨NNT : 2019SORUS564⟩. ⟨tel-03349927⟩

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