Open Access

ABSTRACT

On the Validity of the Fracture Mechanics Approach to Hydrogen Assisted Cracking

J. Toribio¹, V. Kharin²

1 Materials Engineering Department, University of Salamanca, Campus Viriato, 49022 Zamora, Spain
2 Materials Engineering Department, University of Salamanca, Campus Viriato, 49022 Zamora, Spain

The International Conference on Computational & Experimental Engineering and Sciences 2008, 7(3), 135-140. https://doi.org/10.3970/icces.2008.007.135

Abstract

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.

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