Interaction of aluminium with hydrogen in twinning-induced plasticity steel

Alloying with aluminium can mitigate the hydrogen embrittlement of twinning-induced plasticity (TWIP) steels. First-principles calculations indicate a new mechanism for this observation, namely that Al atoms are weak traps for hydrogen, because of local dilation around them. This in turn allows the Al-containing steel to absorb more hydrogen, as confirmed by previously unexplained observations in the literature. Calculations using the Oriani theory show that Al can retard the diffusion of hydrogen in TWIP steel via the atomic trapping mechanism. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.