The role of density functional theory in decoding the complexities of hydrogen embrittlement in steels

Hydrogen (H) is considered as the key element in aiding the initiated green energy transition. To facilitate this, efficient and durable technologies need to be developed for the generation, storage, transportation, and use of H. All these value chain stages require materials that can withstand continuous exposure to H. Once absorbed, H can eventually concentrate to critical levels in a stressed microstructure, inducing specific damage mechanisms and consecutive loss of mechanical properties. This is known as hydrogen embrittlement (HE). Being one of the most significant structural material types, steels are widely used throughout the H value chain. They can suffer from HE, and numerous attempts are made towards understanding and mitigating this complex phenomenon. While originating at a size scale of atoms, HE acts on multiple spatio-temporal scales, and combined efforts of experimental and modelling techniques are needed to deal with it. This perspective is devoted to assimilating the knowledge that can be generated by density functional theory (DFT) methods to understand interactions between H and iron-based materials, and to promote finding solutions to HE in metallic materials in general. We aim to provide a comprehensive understanding of the properties calculated using DFT that can help advance finding novel H-resistant high-strength materials that facilitate the green shift at sufficient performance levels to meet the growing future needs.