Metal alloys are essential materials at all levels for the production, storage, or transport of hydrogen. The goal of this project is to enhance fundamental knowledge on the interactions at atomic scales between hydrogen and crystalline defects or carbides in steels. This is a topic with a high impact since it is linked to hydrogen embrittlement, a phenomenon with major industrial consequences. Several phenomenological models already exist, they are mainly based on these hydrogen/defect interactions. However, many unknowns remain about complex or dynamic configurations when other solutes are present (such as carbon in solid solution) or when dislocations interact with carbides. In this thesis work, the interactions between hydrogen, carbon and defects in martensitic steels, model microstructures based on industrial alloys will be studied. the metallurgical states and the distribution of crystalline defects (solutes, dislocations, vacancies, and austenitic grain boundaries) as well as carbides and precipitates can by modified by heat treatments. These microstructures will be characterized by several techniques (in situ XRD-synchrotron, and ex-situ by laboratory techniques - XRD, EBSD, TEM, SEM-FIB-EDS), then the influence of the metallurgical heterogeneities on the solubility, diffusion and trapping of hydrogen will be characterized using different experimental approaches (electrochemical permeation, charging, TDS dosage).
Hydrogen embrittlement, Martensitic steels, Crystalline defects, Hydrogen diffusion
REMICHIRoufeidaLaSIErremichi@univ-lr.fr
