SKM 2021 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 7: Topical Session Interface-Dominated Phenomena - Segregation and Embrittlement

MM 7.5: Vortrag

Mittwoch, 29. September 2021, 12:30–12:45, H8

Ab initio study of hydrogen segregation and embrittlement at grain boundaries in bcc Fe — •Abril Azócar Guzmán, Alexander Hartmaier, and Rebecca Janisch — ICAMS, Ruhr-University Bochum, 44780 Bochum, Germany

Hydrogen embrittlement is a fundamental problem in materials science that affects structural materials such as steel. Grain boundaries in ferritic microstructures play a dual role in the context of hydrogen embrittlement: they could act as H traps and thus reduce the amount of mobile H in the system. Alternatively, this trapping could promote hydrogen enhanced decohesion (HEDE) at the grain boundaries. Understanding the relationship between strain, hydrogen solubility, and cohesive strength can help elucidate the HEDE mechanism and influence the segregation process. We present the results of ab initio studies of the effect of H, as well as C, on Fe at Σ5 and Σ3 symmetrical tilt grain boundaries. The calculated results show that the presence of H significantly reduces both the work of separation and the intergranular cohesive strength; these quantities can aid to derive traction-separation laws for cohesive zone models in mesoscale simulations. Additionally, we analyse the solubility of H under mechanical load, which allows us to predict H distribution in microstructures with residual stresses, or under applied load.