New Approaches to Understanding Hydrogen Embrittlement of Steels

The anticipated major expansion in hydrogen production, transportation and utilisation calls for massive investments in infrastructure. One of the biggest challenges of the hydrogen economy is storage and transport. Current hydrogen storage technology involves either physical storage systems such as pressurised canisters (typically made from steel, which may be embrittled by the cryogenic temperatures and hydrogen exposures- or the synergistic effects of both) or materials such as hydrides which can store hydrogen in a reacted form, that will then need to be extracted. Hydrogen embrittlement in steel at cryogenic temperatures is poorly understood - and lack of mechanistic insights means that material selection or bespoke alloy development remains challenging. Steels that are resistant to embrittlement at room temperature are certainly available but tend to be expensive, and their behaviour under cryogenic temperatures has not been well-explored. Improved fundamental understanding of the processes of hydrogen dissolution in the metal, and the role of microstructural features that act as hydrogen trap sites, will assist in screening steels for hydrogen service. This iCASE project will therefore focus on the experimental investigation of hydrogen dissolution, diffusion and distribution in different steels - with the steels studied and characterized under cryo-conditions. Using new experimental facilities at Imperial, we have a chance to create a step-change in understanding of the properties. The experimental work will be supported by numerical modelling, leading to a workflow for characterising candidate steels for hydrogen service.