Researchers from the University of Groningen in the Netherlands, including Aleksei Egorov, Lei Zhang, Erik van der Giessen, and Francesco Maresca, have conducted a study to better understand how hydrogen affects the strength and durability of steel, a critical material in the energy industry. Their findings, published in the journal Nature Communications, shed light on the atomic-scale mechanisms behind hydrogen embrittlement, a phenomenon that can compromise the integrity of steel structures.
Steel is widely used in the energy sector due to its strength and ductility, which allows it to deform without fracturing. However, when exposed to hydrogen, steel can become brittle and prone to cracking, a process known as hydrogen embrittlement. This issue is particularly relevant for industries where hydrogen is used, such as in hydrogen fuel cells or in the production and transport of hydrogen gas.
The researchers developed a sophisticated machine-learning potential that accurately models the interactions between hydrogen atoms and iron at the atomic scale. Using this potential, they performed large-scale molecular dynamics simulations to study crack propagation in iron with and without hydrogen. Their simulations revealed that, in the absence of hydrogen, iron exhibits ductile behavior, with cracks blunting and dislocations emitting, which helps to prevent catastrophic failure. However, even minute concentrations of hydrogen can switch the crack-tip behavior from ductile to brittle, leading to rapid crack propagation and failure.
The study found that the combination of fast hydrogen diffusion and diminished surface energy is responsible for the embrittlement. Hydrogen atoms quickly diffuse to the crack tip, reducing the surface energy and facilitating brittle fracture. Based on these findings, the researchers propose a modified Griffith’s criterion for hydrogen-induced brittle fracture, which can be used to assess embrittlement in iron-based alloys.
For the energy industry, these findings are crucial for developing strategies to mitigate hydrogen embrittlement in steel structures. By understanding the atomic-scale mechanisms behind this phenomenon, engineers can design better materials and safety protocols to ensure the reliable and safe use of steel in hydrogen-related applications. This research highlights the importance of continued investigation into the interactions between materials and hydrogen, as the energy sector increasingly turns to hydrogen as a clean and sustainable energy source.
This article is based on research available at arXiv.