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DRT: Thesis subject SL-DRT-20-0470

RESEARCH FIELD
Additive manufacturing, new routes for saving materials / Technological challenges
TITLE English Français

Microstructural changes in additive manufacturing materials during Hot Isostatic Pressing: modelling and experimental study

ABSTRACT

Additive manufacturing (AM) processes are promising techniques for manufacturing metallic components from powder or wire feedstock. AM materials exhibit microstructures very different from cast or forged equivalent materials. They are out of equilibrium, sometimes anisotropic, with specific features like a high dislocation density and defects (unmelted particles, pores) which may be detrimental to mechanical properties (creep, fatigue resistance). Defects can be mitigated using a heat treatment under high gas pressure (hot isostatic pressing HIP), at the expense of material softening.

The objective of the PhD thesis is to model the microstructural évolutions during HIP in order to optimise the HIP cycle for a given AM microstructure: defects shall be decreased enough while softening shall be limited.

A detailed characterisation of the initial microstructure will be done (defects, grain size, dislocation density, precipitates, texture…) in order to provide data for the DIGIMU software. This software uses the level set method to simulate, by finite element calculation, the evolution of a volumic element representative of a microstructure during thermomechanical loading. This software will be enriched. The comparison between modelled evolution and experimentally observed ones will be used to assess the relevancy of the modelling (HIP will be applied on samples). Furthermore, attention will be paid to the evaluation of the impact of the HIP treatment on mechanical properties of AM material (316L steel will be used).

LOCATION
Département Thermique Biomasse et Hydrogène (LITEN)
Service Composants Thermiques et Réacteurs
Laboratoire Conception et Assemblages
Place: Grenoble
Start date of the thesis: 01/10/2020
CONTACT PERSON

Emmanuel RIGAL  

CEA
DRT/DTBH//LCA
Liten/DTBH/SCTR/LCA, CEA Grenoble,
17 rue des Martyrs,
38054 Grenoble Cedex 9, FRANCE

Phone number: +33 4 38 78 97 22

UNIVERSITY / GRADUATE SCHOOL
MINES ParisTech
Sciences Fondamentales et Appliquées - Nice -
THESIS SUPERVISOR

Marc BERNACKI

mines paris tech
cemef
cemef
1, rue Claude Daunesse - CS 10207
06904 SOPHIA ANTIPOLIS Cedex France