Detection of voids in hydrogen embrittled iron using transmission X-ray microscopy

Hydrogen embrittlement remains a barrier to widespread adoption of hydrogen as a carbon-neutral energy source. Here, hydrogen embrittlement mechanisms are investigated across length scales in iron using transmission X-ray microscopy (TXM), digital image correlation (DIC), and notched tensile testing during in-situ electrochemical hydrogen charging. TXM reveals void size and spatial distribution ahead of a propagating crack. We find hydrogen charging leads to voids within similar to 10 mm of the crack tip and suppression of voids beyond this distance. Near the crack tip, voids are elongated in the direction of the crack and are smaller than voids in an uncharged sample. In the presence of hydrogen, these voids lead to quasi-cleavage fracture and a sharper crack tip. DIC shows localization and reduction of plastic strain with hydrogen charging, and tensile testing reveals a reduction in fracture energy and elongation at failure. These results are discussed in the context of hydrogen embrittlement mechanisms. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Investigation of hydrogen embrittlement mechanisms in iron using TXM, DIC, and in-situ electrochemical hydrogen charging reveals void formation and crack propagation behavior. Hydrogen charging leads to the formation of voids near the crack tip, resulting in quasi-cleavage fracture and a sharper crack tip. Plastic strain localization and reduction, as well as reduced fracture energy and elongation at failure, are observed with hydrogen charging. These findings contribute to the understanding of hydrogen embrittlement mechanisms.