Stress Corrosion Cracking and Hydrogen Embrittlement: Differences and Similarities.
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF MATERIALS SCIENCE AND ENGINEERING
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Over the years many criteria have been proposed for distinguishing, phenomenologically at least, stress corrosion cracking from hydrogen embrittlement. At one time, for example, the susceptibility of an alloy to cracking at anodic potentials was considered characteristic of a material sensitive to SCC. Conversely, increased sensitivity at cathodic potentials was considered evidence of HEM. This potential dependence is clearly an uncertain criterion since it is now appreciated that crack tip conditions potential and pH may vary considerably from those more easily measured at the bulk metalelectrolyte interface. In this discussion, we will trace the development, and dismissal in some cases, of various criteria for distinguishing SCC from HEM based on, for example, hydrogen-induced phase transformations in the solid, the observation of hydrogen evolution from the tip of a propagating crack, fractography, crystal structure, critical anionic species in the electrolyte, loading mode during deformation, and the influence of solid state impurities. Author
- Properties of Metals and Alloys
- Test Facilities, Equipment and Methods