Professor Felix Hofmann leads world-first 3D real-time imaging of hydrogen in steel

A world-first study led by Felix Hofmann, Trinity Lecturer and alumnus, and Professor of Engineering Science at Oxford, has revealed how hydrogen atoms dynamically alter the internal structure of stainless steel, with important implications for the development of safe hydrogen-based technologies.

Researchers at the University of Oxford and Brookhaven National Laboratory used an advanced X-ray imaging technique to capture three-dimensional, real-time images of how internal defects, known as dislocations, respond to hydrogen exposure. The findings help explain hydrogen embrittlement - a major challenge for pipelines, storage vessels, and components in hydrogen-powered systems.

The team used Bragg Coherent Diffraction Imaging at the Advanced Photon Source in the United States to observe a single stainless-steel grain approximately 700 nanometres in diameter. Over 12 hours, the experiment revealed that hydrogen increases the mobility of dislocations, enables unexpected out-of-plane motion, and reduces the strain fields surrounding defects - providing the first direct experimental evidence of hydrogen elastic shielding.

Professor Hofmann said:

“Using coherent X-ray diffraction, we were able to watch atomic-scale events unfold in real time inside solid metal without cutting open the sample. Some of the results really surprised us by showing behaviour we weren’t expecting.”

The findings will help inform the design of new alloys and improve predictive models for materials operating in hydrogen-rich environments, supporting the transition to low-carbon energy systems.

The research paper 'Direct Imaging of Hydrogen-Driven Dislocation and Strain Field Evolution in a Stainless Steel Grain' is published in Advanced Materials.