LAUSR

Hydrogen-induced slow crack growth exhibits, in general, three distinct stages of crack growth kinetics, and stages I and II are controlled by hydrogen diffusion. A model that describes the kinetics of crack growth caused by internal hydrogen (in stages I and II) is proposed on the basis of the linear elastic fracture mechanics, stress-induced hydrogen diffusion theory and hydrogen-enhanced decohesion mechanism for hydrogen-induced cracking. The model predicts the crack growth rate da/dt for both stages I and II as a function of the stress intensity factor KI and the initial level of hydrogen concentration. Some experimental data reported in the literature are used to validate the model and good agreement is obtained.