Hydrogen in Steels – A transition scales problem – Hy-Style

Metallic materials are major components at every level of hydrogen usage, namely production, transportation and storage. The aim of this project is to deepen the knowledge on atomic scale interactions between hydrogen and crystalline defects or carbides in steels. The topic is of high importance as it is related to hydrogen embrittlement, a critical industrial issue. Various phenomenological models have been proposed to account for hydrogen embrittlement, they are mostly connected to interactions between hydrogen and crystalline defects. Little is known however in complex or dynamic situations where other solutes interact with these defects (such as carbon in solid solution) or when defects such as dislocations interact with second phase particles that have potentially captured some hydrogen atoms (carbides). In this context, our objective is to provide a better understanding of the influence of H on the behavior of dislocations in the iron-carbon system, where solid solution, or carbides or grain boundaries are involved. A special emphasis will be given on the competition between H and C, two interstitial elements in bcc Fe, with a unique combination of atomic scale characterization and atomic scale modelling to provide new and unique information about the fundamental mechanisms of hydrogen induced material failure. The project is divided in four work packages that will address specific issues: 1) Hydrogen, carbon and dislocations; 2) Hydrogen, carbon and grain boundaries; 3) Hydrogen and carbides; 4) Understanding the influence of H on mechanical properties. Five complimentary partners are gathered to address these challenges using atomic scale modelling (kinetic Monte Carlo and quasiparticle approach) in close connection with experimental data that will be collected by TEM, TDS, HERXD and APT. The output of the HySteel project will be a better understanding of the influence of H on the relationship between structural features and mechanical properties in steel.