Hydrogen embrittlement through the formation of low-energy dislocation nanostructures in nanoprecipitation-strengthened steels.

Gong, P; Nutter, J; Rivera-Diaz-Del-Castillo, P E J; Rainforth, W M · Sci Adv · 2020

basic_science · Level V

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Abstract

Hydrogen embrittlement is shown to proceed through a previously unidentified mechanism. Upon ingress to the microstructure, hydrogen promotes the formation of low-energy dislocation nanostructures. These are characterized by cell patterns whose misorientation increases with strain, which concomitantly attracts further hydrogen up to a critical amount inducing failure. The appearance of the failure zone resembles the "fish eye" associated to inclusions as stress concentrators, a commonly accepted cause for failure. It is shown that the actual crack initiation is the dislocation nanostructure and its associated strain partitioning.