A micromechanical analysis of swelling-induced embrittlement in neutron-irradiated austenitic stainless steels - Archive ouverte HAL Access content directly
Journal Articles Journal of Nuclear Materials Year : 2022

A micromechanical analysis of swelling-induced embrittlement in neutron-irradiated austenitic stainless steels

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Abstract

Swelling is commonly observed in austenitic stainless steels irradiated at high doses and high temperatures, such as fuel claddings in Fast-Breeder Reactors FBR), as a consequence of the formation of irradiation-induced nanovoids. Macroscopic embrittlement has been reported above a critical swelling level. Several physical explanations have been proposed such as void-related fracture mechanisms and phase transformation associated with local changes of microchemistry. In addition, structural effects can affect the critical swelling level, tentatively explained by local corrosion, swelling gradient and bending effects. In order to ddress these phenomena, an extended experimental database is first presented, based on fuel pins irradiated in the Phénix fast reactor, showing the evolution of conventional tensile properties with swelling. SEM and TEM analysis are also summarized to highlight specific embrittlement mechanisms related to the presence of voids. Micromechanical simulations are then performed based on porous materials constitutive equations in order to rationalize the experimental observations. Analytical and numerical results show that swelling-induced embrittlement can be understood from a mechanical perspective as a transition from void growth to void coalescence deformation mode. The effect of the spatial heterogeneity of void distribution is quantified and shown to be a key parameter. Structural effects coming from tests performed on ring and axial tensile specimens and from the presence of a swelling gradient in cladding thickness are also quantified. Numerical results are compared to experimental data, and a good agreement is observed.
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Dates and versions

cea-03748669 , version 1 (09-08-2022)

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Jeremy Hure, Arnaud Courcelle, Isabelle Turque. A micromechanical analysis of swelling-induced embrittlement in neutron-irradiated austenitic stainless steels. Journal of Nuclear Materials, 2022, pp.153732. ⟨10.1016/j.jnucmat.2022.153732⟩. ⟨cea-03748669⟩
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