Ultra High Purity Alloys for the Study of Hydrogen Effects on Fatigue Mechanisms in Ni and Ni–Cr–Fe at 300 K

Abstract

Low‐cycle fatigue and corrosion fatigue mechanisms of ultra‐high‐purity (UHP) Ni and Ni‐base alloys in H2SO4 solutions are analysed. UHP materials are used to eliminate the impurity effects, including those on grain boundaries which can promote hydrogen embrittlement. Particular attention is paid to the conditions for hydrogen absorption and its effect on damage processes. Hydrogen embrittlement is analysed in terms of persistent slip band–grain boundary (PSB–GB) interactions and hydrogen diffusion short circuits at grain boundaries. The effect of chromium on the kinetics of the PSB formation as well as on both anodic dissolution and hydrogen absorption is emphasised.

The Use of Ultra-High-Purity Metals and Alloys to Study Environment-Sensitive Damage Mechanisms in Nuclear Power Plants

“…In fact, similar experiments on polycrystals do not result in the formation of a stress plateau. Moreover, hydrogen grain-boundary diffusion together with stress concentrations due to the formation of PSB, would result in very fast crack propagation and fracture [21].…”