A collaborative team lead by researcher Dr. David Yang (Brookhaven National Laboratory, Argonne National Laboratory), and principal investigator Prof. Felix Hofmann (Department of Engineering Science, University of Oxford) has carried out the first in situ three-dimensional imaging of how hydrogen interacts with structural defects in stainless steel under realistic conditions. Their work focuses on one of the long-standing problems in clean energy engineering: hydrogen embrittlement, the process by which hydrogen causes metals to weaken or fail unexpectedly.
Yang, D., Seif, M., He, G., Song, K., Morez, A., de Jager, B., Nykypanchuk, D., Harder, R. J., Cha, W., Tarleton, E., Robinson, I. K., & Hofmann, F. (2025). Direct Imaging of Hydrogen‐Driven Dislocation and Strain Field Evolution in a Stainless Steel Grain. Advanced Materials. https://doi.org/10.1002/adma.202500221
To explore this phenomenon, the researchers examined a single stainless steel grain about 700 nanometers wide that contained a known defect known as a dislocation. Using Bragg Coherent Diffraction Imaging (BCDI) and an electrochemical hydrogen charging setup, they observed how the defect and its surrounding strain field evolved over a 12-hour period as hydrogen entered the sample. This approach, made possible by the highly coherent X-ray beams available at the Advanced Photon Source, allowed the team to watch hydrogen in action inside bulk metal, something that has not been achieved before.
Prof. Felix Hofmann (Department of Engineering Science, University of Oxford) stated,
“This research is only possible because of the availability of extremely bright and coherent X-ray beams at international synchrotron sources. The results are highly complementary to information from electron microscopy and simulations. We are now planning even more sophisticated experiments to study how hydrogen changes other types of defects. At the same time, we’re also developing models to help industry design complex hydrogen fuel systems.”
The results showed that dislocations inside the steel became significantly more mobile once hydrogen was introduced. Even in the absence of applied external stress, defects were able to move and reshape themselves, suggesting that hydrogen plays a role in reducing the barriers that normally keep such defects in place. In addition, the researchers observed out-of-plane motion, known as “climb,” which is unusual under these conditions at room temperature and points to hydrogen enabling atomic rearrangements not typically seen in stainless steel. Another key finding was that the strain fields surrounding the defects diminished noticeably as hydrogen accumulated. This reduction supports a long-theorized mechanism known as elastic shielding, in which hydrogen lowers the stress felt by the surrounding material.
These observations provide a new window into why hydrogen can destabilize metals. By enabling defects to move more easily and in unexpected ways, hydrogen effectively undermines the strength of the material, which helps explain how sudden cracks or failures can occur in pipelines, storage tanks, and other components exposed to hydrogen. The study not only verifies theoretical predictions but also supplies quantitative data that can be fed into the simulation models used by engineers to predict material performance.
While the experiments were carried out under controlled conditions on a single steel grain, the implications extend to larger-scale engineering systems. Bulk components used in hydrogen infrastructure contain many grains, complex microstructures, and varied types of defects, all of which may interact with hydrogen in ways that compound the effects observed here. The team emphasizes that future work will involve studying other defect types, different hydrogen concentrations, and the influence of external loading.
The findings also highlight directions for materials design. Alloys that can resist hydrogen’s tendency to increase defect mobility or promote defect climb could be critical for the long-term reliability of hydrogen technologies. Engineers may also need to consider microstructural factors, such as grain size and defect density, when selecting materials for hydrogen service. Testing methods that capture dynamic, real-time changes rather than only end-state damage will be increasingly important in evaluating material performance.
This research represents an important step in connecting atomic-scale phenomena with real-world engineering challenges. As countries and industries push forward with hydrogen as a clean energy carrier, understanding and controlling hydrogen embrittlement will be central to building safe and durable systems. The study, published in Advanced Materials, moves the field closer to that goal by offering a rare view into the nanoscale processes that dictate how metals behave when exposed to hydrogen.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
