Some technology gaps in the detection and prediction of hydrogen-induced degradation of metals and alloys

One hundred years of study and thousands of individual investigations have led to some understanding of the deleterious effects of hydrogen on the mechanical behavior of metals and alloys. This understanding includes a technical basis to: (a) evaluate the potential for hydrogen-induced degradation through mechanistic, phenomenological, and/or empirical models of the embrittlement process(es), (b) categorize the type of damage in terms of the active or dominant degradation mechanism, (c) select materials to minimize the susceptibility to hydrogen-induced degradation, and (d) avoid the potentially adverse effects of hydrogen exposure through processing and service. The emergence of understanding has not been accompanied by the emanation of nondestructive evaluation technologies to detect the early stages of degradation. Moreover, the ability to predict the susceptibility of new engineering alloys to hydrogen embrittlement is very limited. Data and/or analyses to describe the effects of hydrogen on welds and other as-cast structures are also lacking. This paper provides a brief description of the various embrittlement processes and discusses the technology gaps in the development of nondestructive evaluation technologies to predict and/or monitor hydrogen-induced degradation of high-strength steels and other metals and alloys.