The effect of strain rate on hydrogen distribution in round tensile specimens

Round bars under tensile loading are modelled using coupled diffusion elastic–plastic finite element analyses based on a hydrogen transport model. High strain rates result in low hydrogen concentrations in lattice sites, while low strain rates result in high hydrogen concentrations in lattice sites. This could be an explanation why at slow tensile tests a low ductility is observed while this is not observed at high strain rates. However, no unique criterion for the ductility based on the hydrogen concentration and the strain rate could be derived.