Protection of metal interfaces against hydrogen-assisted cracking.

Enabling a hydrogen economy requires the development of materials resistant to hydrogen embrittlement (HE). More than 100 years of research have led to several mechanisms and models describing how hydrogen interacts with lattice defects and leads to mechanical property degradation. However, solutions to protect materials from hydrogen are still scarce. Here, we investigate the role of interstitial solutes in protecting critical crystalline defects sensitive to hydrogen. Ab initio calculations show that boron and carbon in solid solutions at grain boundaries can efficiently prevent hydrogen segregation. We then realized this interface protection concept on martensitic steel, a material strongly prone to HE, by doping the most sensitive interfaces with different concentrations of boron and carbon. These segregations, in addition to stress relaxations, critically reduce the hydrogen ingress by half, leading to an unprecedented resistance against HE. This tailored interstitial segregation strategy can be extended to other metallic materials susceptible to hydrogen-induced interfacial failure.