Cracked High-strength Bolt Under Cycling and Hydrogen Environment Durability Estimation Using Accurate and Approximate Models

Different crack propagation empirically models to estimate the crack propagation in structure components, which are simultaneously subjected to cycling and aggressive hydrogen environment influence are reported. The paper describes kinetics of a crack in the thread root of the bolt from high-strength steel AISI 4340 under cycling loading in aggressive hydrogen environment using empirically-specified model and approximate one.The approximate model is based on the possibility of the Paris-Erdogan constants improving for hydrogen environment. The new constants will differ from those of for inert environment. This new constants help to estimate the considered crack kinetics in high-strength bolts subjected to current hydrogen environment. Moreover, the empirically-specified and approximate models help to estimate the durability of the considered cracked high-strength bolts.