Department of Engineering Science. University of Oxford
Hydrogen embrittlement
When first observed, the interaction between hydrogen and metals was described as “remarkable” and “extraordinary”. When metallic materials are exposed to a hydrogen-containing environment, hydrogen is absorbed into the material and this dissolved hydrogen causes a dramatic degradation in mechanical properties, a phenomenon referred to as hydrogen embrittlement. As little as a few parts per million (ppm) of hydrogen can change – by orders of magnitude – a metal’s ductility (elongation), fracture toughness, and fatigue crack growth rates. The phenomenon of hydrogen embrittlement has attracted the attention of the material science and solid mechanics communities for decades due to its scientific complexity and its important technological implications - hydrogen-assisted failures are pervasive across the transport, defence, energy, and construction sectors. Moreover, the problem has come very much to the fore in recent years as a consequence of the higher susceptibility of new, high-strength alloys, and because of the promise that hydrogen holds as a future energy carrier, requiring the development of suitable structures for hydrogen storage and transport. Hydrogen embrittlement is considered one of the biggest impediments to the broader implementation of a hydrogen-based fuel economy, hindering the transition away from fossil fuels. However, 150 years after this phenomenon was first observed, its underlying physical mechanisms are as debated as ever, hindering the prediction of hydrogen-assisted failures and the development of hydrogen-resistant materials. We have tried to shed new light on this complex phenomenon and build upon this new understanding to accelerate the deployment of a hydrogen energy infrastructure. Among others, we have engaged in the following endeavours in this area:
Developing new isothermal desorption spectroscopy TDS (ITDS) methodologies to accurately measure hydrogen diffusivity in metals.
Combining modelling and electrochemical experiments to establish an equivalence between hydrogen uptake from gaseous and electrochemical environments.
Characterising the hydrogen embrittlement susceptibility of additively manufactured metals, across temperatures and post-processing treatments.
Developing mechanistic, multi-scale models of hydrogen uptake, transport and embrittlement, to reliably predict hydrogen-assisted failures.
Developing robust hydrogen-assisted fracture models that can deliver predictions over the large scales and complex conditions of engineering practice. These have been used to assist in the design of hydrogen storage components and to determine the conditions in which hydrogen can be transported in the existing natural gas pipeline infrastructure.