Effet du chargement mécanique et du trajet de déformation sur la corrosion sous contrainte d'un acier inoxydable austénitique en milieu primaire de RE // Effect of mechanical loading and strain path on stress corrosion cracking of austenitic stainless ste

Ce travail de thèse a pour objectif d'étudier l'effet du chargement mécanique et de la déformation, en particulier le mode et le niveau de déformation, sur la résistance à l'amorçage de fissures de corrosion sous contrainte d'un acier inoxydable en milieu primaire des réacteurs à eau sous pression.
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The aim of this thesis is to study the effect of mechanical loading and deformation, in particular the mode and strain level, on the susceptibility to stress corrosion cracking initiation of stainless steel in the primary water of pressurised water reactors.

Context and challenges:
Stainless steels are widely used in the primary circuit of pressurised water reactors (PWRs) because of their good corrosion resistance and mechanical properties. Generally speaking, feedback on the use of stainless steels in PWRs is very positive. However, some grades, such as 304L and 316L steels are susceptible to stress corrosion cracking (SCC) under certain service conditions [1]-[3].
SCC is a highly complex surface degradation phenomenon resulting from a synergistic effect between a material, tensile stresses (residual or service) and an aggressive environment. Under service conditions, SCC cracking of stainless steel components is mainly observed in occluded areas, where the environment cannot renew itself properly [1], [2]. Feedback has also shown that work-hardening of stainless steels is a key factor, and often a necessary one, in initiating SCC cracking.
At the end of 2021, new cases of cracking affecting stainless steel piping in the French nuclear fleet were detected. No deviation either of water chemistry or c work hardening was observed where these cracks were initiated. The mechanisms behind SCC cracking in cold-worked stainless steels in a primary environment are still largely unknown at the present time.

Scientific objectives:
In this context, the objective of the thesis is to evaluate the effect of the type of mechanical loading and deformation, in particular the mode and level of deformation, on the resistance to SCC crack initiation of a stainless steel in a PWR primary environment.
Since SCC is a surface phenomenon, the impact of different surface finishes (laboratory polishing vs. industrial surface finish) will also be studied. In order to establish a correlation between factory-produced microstructures and the SCC resistance of components in service, numerical work will be integrated into the thesis. This work will be based on experimental data collected during the thesis.

Expected results:
This subject offers candidates the opportunity to tackle an industrial problem using a multidisciplinary scientific approach, combining metallurgy, mechanics, physical chemistry and numerical modelling. The skills acquired can then be easily exploited in the pursuit of an industrial or academic career.
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Début de la thèse : 01/10/2024
WEB : https://www.mat.minesparis.psl.eu/formation/doctorat/propositions-de-sujets-de-these/

Cifre

CIFRE ANRT

Mines Paris-PSL

621 ISMME - Ingénierie des Systèmes, Matériaux, Mécanique, Énergétique

Profil type pour une thèse à MINES ParisTech: Ingénieur et/ou Master recherche - Bon niveau de culture générale et scientifique. Bon niveau de pratique du français et de l'anglais (niveau B2 ou équivalent minimum). Bonnes capacités d'analyse, de synthèse, d'innovation et de communication. Qualités d'adaptabilité et de créativité. Capacités pédagogiques. Motivation pour l'activité de recherche. Projet professionnel cohérent. Pré-requis (compétences spécifiques pour cette thèse): Master recherche ou ingénieur en science des matériaux et/ou mécanique. Capacité à effectuer des travaux expérimentaux indispensable. Des compétences en calcul numérique et /ou en corrosion seraient un plus. Pour postuler: Envoyer votre dossier à recrutement_these@mat.mines-paristech.fr comportant un curriculum vitae détaillé une copie de la carte d'identité ou passeport une lettre de motivation/projet personnel des relevés de notes L3, M1, M2 2 lettres de recommandation les noms et les coordonnées d'au moins deux personnes pouvant être contactées pour recommandation une attestation de niveau d'anglais
Typical profile for a thesis at MINES ParisTech: Engineer and / or Master of Science - Good level of general and scientific culture. Good level of knowledge of French (B2 level in french is required) and English. (B2 level in english is required) Good analytical, synthesis, innovation and communication skills. Qualities of adaptability and creativity. Teaching skills. Motivation for research activity. Coherent professional project. Prerequisite (specific skills for this thesis): Master's degree in research or engineer in materials science and/or mechanics. Ability to carry out experimental work essential. Skills in numerical calculation and/or corrosion would be a plus. Applicants should supply the following : a detailed resume a copy of the identity card or passport a covering letter explaining the applicant's motivation for the position detailed exam results two references : the name and contact details of at least two people who could be contacted to provide an appreciation of the candidate Your notes of M1, M2 level of English equivalent TOEIC to be sent to recrutement_these@mat.mines-paristech.fr