Chemical and Biomolecular Engineering Faculty Research


Modeling of the Factors Contributing to the Initiation and Propagation of the Crevice Corrosion of Alloy 625

Document Type


Publication Date

Summer 1994


Crevice corrosion of alloy 625 in both chlorinated and nonchlorinated American Society for Testing and Materials (ASTM) artificial ocean water was modeled. Secondary current and potential distributions as a function of crevice depth were obtained from the model using the following crevice initiation criteria (i) , (ii) , and (iii) pH −0.46 at the site where the first two criteria are met. For alloy 625 in nonchlorinated ASTM artificial ocean water these criteria are satisfied at depths which are near the mouth of the crevice. These depths are incompatible with the mass‐transport conditions governing the development of the critical crevice solution. In the chlorinated system the model predicts that initiation occurs at greater depths which are compatible with all the criteria including mass‐transport considerations. The model results are in agreement with remote crevice assembly experiments which show that crevice corrosion occurs more readily in the chlorinated ASTM artificial ocean water. Propagation of the crevice corrosion of alloy 625 is shown to be ohmically controlled by the resistance between the mouth of the crevice and the initiation site.





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