Hydrogen Effect against Hydrogen Embrittlement

Abstract

The well-known term ''hydrogen embrittlement'' (HE) expresses undesirable effects due to hydrogen such as loss of ductility, decreased fracture toughness, and degradation of fatigue properties of metals. However, this article shows, surprisingly, that hydrogen can have an effect against HE. A dramatic phenomenon was found in which charging a supersaturated level of hydrogen into specimens of austenitic stainless steels of types 304 and 316L drastically improved the fatigue crack growth resistance, rather than accelerating fatigue crack growth rates. Although this mysterious phenomenon has not previously been observed in the history of HE research, its mechanism can be understood as an interaction between hydrogen and dislocations. Hydrogen can play two roles in terms of dislocation mobility: pinning (or dragging) and enhancement of mobility. Competition between these two roles determines whether the resulting phenomenon is damaging or, unexpectedly, desirable. This finding will, not only be the crucial key factor to elucidate the mechanism of HE, but also be a trigger to review all existing theories on HE in which hydrogen is regarded as a dangerous culprit.

Micro-Portion Image Analysis of Light Elements in Fe–Cr Based Alloys by Time-of-Flight Secondary Ion Mass Spectrometry

“…The characteristic distribution of deuterium is considered to result from diffusion paths in the ferrite, as the diffusivity in the ferrite is known to be much higher in the ferrite than in the austenite. 40) It is noted that deuterium seems to be enriched in the ferrite side close to the interface between the ferrite and the austenite. Since the practical morphology of the interface is complicated, deuterium may be trapped in such complicated microstructure.…”

Hydrogen-Induced Effects in Annealed and Prestrained 316L-Type Stainless Steel Studied by Mechanical Spectroscopy

“…The hydrogen content was estimated using the method described by Murakami et al in [10], which had shown satisfactory consistency with experimental data. The calculated values are presented in Table 1.…”

Hydrogen Embrittlement Mechanism in Fatigue Behaviour of Austenitic and Martensitic Stainless Steels

“…They can occur separately or in combination, so that different mechanisms can take the dominant role during crack initiation and crack growth. Most of the research on hydrogen embrittlement of stainless steels deals with the characterization of long fatigue crack growth behaviour [2,3] or the effect of hydrogen on monotonic properties obtained in tensile tests [4,5]. There is only little information available about the mechanisms of crack initiation and early crack growth.…”