Hydrogen-induced brittle fracture in nickel based alloy 82 weld metal

Abstract

Alloy 82 weld metal is sensitive to hydrogen assisted fracture and low-temperature crack propagation.Novel ex-situ and in-situ mechanical testing, and hydrogen charging techniques were combined with post-test fractography to investigate this effect. Electrolytic hydrogen charging followed by mechanical testing confirmed a reduction in the elongation to failure and fracture strength. The reduction in mechanical behaviour correlated with the transition from ductile to inter-granular (IG), inter-dendritic (ID), and cleavage-type brittle fracture modes. In-situ low temperature crack propagation testing at 54°C confirmed the presence of brittle inter-granular fracture as a result of hydrogen absorbed during exposure to the aqueous test environment.