2016 05 26 PhD defense

The use of duplex stainless steel (DSS) grades for structural applications is considered as one of the most significant advances impacting the construction sector. This is because of their high mechanical properties coupled with interesting functional properties such as corrosion resistance or their low thermal conductivity compared to carbon steels. A better understanding of the relationship between their microstructure and properties is needed to obtain breakthrough properties and to provide the possibility to design tailor-made, architectured DSS for specific applications. In this work we propose a top-down strategy in which at least two bulk metals with well-known properties are mechanically alloyed by Severe Plastic Deformation (SPD). This proposed strategy serves two main objectives: i) enhancing the properties by microstructure refinement down to sub-micron scale ii) elaborating a model material for understanding the behavior of DSS obtained by the conventional metallurgical methods. The first objective of this work was the implementation of a manufacturing methodology using co-drawing, aiming at obtaining an ultra-fine microstructure of 316L/430LNb composites. One of the challenges met during our study was the significant inter-diffusion during the heat-treatment step necessary during processing preventing by consequence refining below the µm scale. An optimization investigation was carried out to account for this inter-diffusion for 316L/430LNb couple. Multi-scale micro-composites have then been obtained. The limitation of this process in terms of microstructure refinement has been rationalized by a systematic study of recrystallization and diffusion kinetics. In parallel with the microstructural evaluation, the mechanical behavior of these new micro-composites was examined. In situ tensile tests using high energy X-ray synchrotron enabled an in-depth understanding of the plastic interaction of the two phases.

J’ai le plaisir de vous inviter à ma soutenance de thèse qui aura lieu le jeudi 26 mai 2016 à 10h dans l’amphi Jean Besson (PHELMA campus) ainsi qu’au pot qui suivra.

Mon travail de thèse a été réalisé dans le cadre d'une collaboration entre UGITECH, Centre de Recherche d’Ugitech (CRU), et le Center of Excellence of Multifunctional Architectured Materials (CEMAM) sous la direction de M.Alexis Deschamps, M.Marc Mantel et co-encadrée par Mme. Muriel Véron. Cette thèse a été financée par le Labex CEMAM. L'ensemble de mon travail s'est déroulé au sein du laboratoire SIMaP (Grenoble INP) et au centre de recherche d’Ugitech.

L’intitulé de ma thèse est : Développement de microcomposites architecturés en aciers inoxydables duplex: élaboration, microstructure et propriétés mécaniques. (résumé figurant plus bas).

 

Jury :

¨       M. Ludovic THILLY, Professeur, Université de Poitiers, Rapporteur

¨       M. Eric MAIRE, Directeur de Recherche, CNRS, Rapporteur

¨       M. Sébastien ALLAIN, Professeur, Université de Lorraine, Examinateur

¨       M. Alexis DESCHAMPS, Professeur, Grenoble-INP, Directeur de thèse

¨       M. Marc MANTEL, Professeur PAST, Grenoble-INP, co-directeur de thèse

¨       Mme. Muriel VERON, Professeur, Grenoble-INP, Co-encadrant de thèse

¨       M. Guillaume PARRY, Maître de Conférence HDR, Grenoble-INP, invité