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Hydrogen reduces the service life of many metallic components. Such reductions may be manifested as blisters, as a decrease in fatigue resistance, as enhanced creep, as the precipitation of a hydride phase and, most commonly, as unexpected, macroscopically brittle failure. This unexpected, brittle fracture is commonly termed hydrogen embrittlement. Frequently, hydrogen embrittlement occurs after the component has been is service for a period of time and much of the resulting fracture surface is distinctly intergranular. Many failures, particularly of high strength steels, are attributed to hydrogen embrittlement simply because the failure analyst sees intergranular facture in a component that served adequately for a significant period of time. Unfortunately, simply determining that a failure is due to hydrogen embrittlement or some other form of hydrogen induced damage is of no particular help to the customer unless that determination is coupled with recommendations that provide pathways to avoid such damage in future applications. This paper presents qualitative and phenomenological descriptions of the hydrogen damage processes and outlines several metallurgical recommendations that may help reduce the susceptibility of a particular component or system to the various forms of hydrogen damage.

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Electrolytic charging of hydrogen into Type 304L stainless steel at room temperature and 100 C (212 F) induced partial transformation) of the austenite to the some martensitic phases [α′ (bcc) and ε (hep)] as are formed by cold-working hydrogen-free austenite at low temperatures (−196 C) (−321 F). No evidence of a hexagonal hydride was found. The formation of the ε phase by cathodic charging suggests that hydrogen lowers the stacking fault energy of austenite. Hydrogen charging expands the austenite lattice, causes the dislocation and stacking fault density to increase with increasing hydrogen concentration, and causes dislocation movement.