Berlin 2008 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 41: Poster SYM Hydrogen in Materials: New Developments

MM 41.14: Poster

Thursday, February 28, 2008, 18:00–20:00, Poster B

First principles analysis of Hydrogen in Manganese-rich austenitic steels — •Lars Ismer, Tilmann Hickel, and Jörg Neugebauer — Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany

Austenitic Mn-rich steels denote a promising new class of steels, since they combine high strength with ductility. Like other high strength steels, however, they are highly sensitive to hydrogen embrittlement (HE). Various microscopic mechanisms have been discussed as source of HE but the dominant mechanism has not been resolved so far. For a quantitative understanding a description of thermodynamic as well as kinetic aspects of the hydrogen-steel interaction is essential. We have therefore employed density functional theory to investigate the solubility and mobility of interstitial H in the austenitic phase of Fe, Mn, and Fe(x)Mn(1-x). For Fe(x)Mn(1-x) in the paramagnetic state our results show a significant increase both in the solubility and mobility of the H impurity with increasing Mn concentration. A detailed analysis shows that this effect is exclusively related to larger lattice volume induced by Mn. In addition we investigated the interaction of H with interstitial carbon. Our results show that at the high C-concentrations characteristic for the Mn steels the H solubility and mobility increase. This effect is caused by an (anisotropic) volume expansion of the lattice.