Temperature effects on hydrogen-induced crack growth susceptibility of iron-based superalloys

Abstract

The effects of temperature on hydrogen-induced crack growth susceptibility were studied in the iron-based superalloy IN903 using hydrogen charged crack growth samples. The measured crack growth rates increased by more than two orders of magnitude as temperature increased from 253 to 298 K. Crack growth rates then decreased at higher temperature. Fracture in all samples initiated by fracture of matrix carbides followed by microvoid formation at slip band intersections and failure of interconnecting slip band segments. Materials and mechanics approaches were then combined to model the fracture process and crack growth rates. Application of the model to the test results showed that the model provides a quantitatively accurate and physically correct description of how hydrogen and temperature interact to control crack growth susceptibility in IN903. It supports the observation that microvoid formation at slip band intersections is the critical event in the fracture process. It further shows that the interaction between crack tip stress fields and trap sites controls crack growth susceptibility.