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Fonctionnalisation de surface de l’Inconel 625 élaboré par fabrication additive par fusion de lit de poudre

Abstract : Currently the development of hydrogen mobility is hampered by the sizes of plants that cannot produce small volumes as close as possible to the distribution points. The emergence of metallic additive manufacturing gives the opportunity to develop compact equipment whose size will make it possible their installation as close as possible to the users. These thesis works are performed in the frame of the project FAIR (Additive manufacturing for the intensification of the reactors). They aim on one hand at developing reactors-exchangers based on the Inconel 625 elaborated by the laser beam melting (LBM) technology, and on the other hand at functionalizing the surface to improve their resistance against Metal Dusting corrosion, making these equipments compatible with their industrialization. Two ways have been followed in this work. The first one is focused on the study of the microstructure of these new materials and its evolution during heat treatment. The second one aims to assess the reactivity of these new materials in oxidizing atmosphere. Several areas of the LBM material have been characterized: the core, the subsurface and the surface zone with important roughness. The heterogeneity of the solidification structure and the associated chemical segregations have been observed. The microstructure of the core alloy is partially restored as elaborating. During the heat treatment, the stored energy induces a structural rearrangement (recrystallization) favoring the formation of special grain boundaries like twinned grain. The influences of temperature (1075 and 1160 ° C) and time of heat treatment on the mechanisms underlying this microstructure evolution have been studied. Although the raw microstructure provides an oxidation resistance at 900°C equivalent to a conventional material (alloy inconel 625 lamited), oxidation of LBM alloy is catastrophic from 125h at 1050°C whatever the surface roughness or the microstructure. These difference cannot be improved with a thermal pre-treatment. An oxidation mechanism, taking into account the microstructural state of the material, has been developped enabling the description of the morphology of the oxidation products as well as the measured oxidation kinetics.
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Submitted on : Wednesday, April 21, 2021 - 11:10:01 AM
Last modification on : Thursday, April 22, 2021 - 3:27:44 AM

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  • HAL Id : tel-03203982, version 1

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Nicolas Ramenatte. Fonctionnalisation de surface de l’Inconel 625 élaboré par fabrication additive par fusion de lit de poudre. Matériaux. Université de Lorraine, 2020. Français. ⟨NNT : 2020LORR0093⟩. ⟨tel-03203982⟩

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