This paper deals with the meaning and significance of the fracture mechanics
approach to hydrogen assisted cracking, analyzing the question of K-dominance not
only over the purely mechanical aspects, but also over the environmental (physicochemical) events. Two key factors able to violate the uniqueness of the crack
growth kinetics curve v = v(K) are discussed: the role of far field (the stress-strain
field which is not K-dominated) and the effect of the history of hydrogenation and
crack growth. The far field is shown to have a minor effect on near-tip hydrogen diffusion, and thus it can only widen the scatter band of crack growth rates in
the near-threshold portion of the v(K)-curve. With regard to the effect of history,
the study reveals that hydrogenation and crack growth are coupled processes, one
influencing the other, so the crack growth kinetics curve v = v(K) is not unique,
although a special regime of steady-state crack growth is seen to exist in which
hydrogen assisted cracking turns out to be a K-dominated process, and the corresponding plot of the steady-state v against K acquires the uniqueness of a material’s
characteristic curve useful in engineering.
Cite This Article
Toribio, J., Kharin, V. (2008). On the Validity of the Fracture Mechanics Approach to Hydrogen Assisted Cracking. The International Conference on Computational & Experimental Engineering and Sciences, 7(3), 135–140.
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