Crevice corrosion general description

General description. In incomplete fusion, complete melting and fusion between the base metal and the weld metal or between individual weld beads does not occur (Fig. 15.8). Incomplete fusion that produces crevices or notches at surfaces can combine with environmental factors to induce corrosion fatigue (Chap. 10), stress-corrosion cracking (Chap. 9), or crevice corrosion (Chap. 2). See Fig. 15.9. 

The tests can be classified into three general categories (i) non-electrochemical tests, (ii) electrochemical tests under open-circuit conditions, and (iii) electrochemical tests under controlled potential or current conditions. Brief descriptions of the more established methods for evaluating crevice corrosion appear in Table 1 along with comments concerning limits of applicability. Details of each method can be found in the literature cited. The reader is also advised to consider one or more of the excellent reviews on test techniques for crevice corrosion [40-45,76,114. ... 

General Description. Crevice corrosion is a form of localized attack that occurs at narrow openings or spaces (gaps) between metal-to-metal or nonmetal-to-metal components. This type of attack results from a concentration cell formed between the electrolyte within the crevice, which is oxygen starved, and the electrolyte outside the crevice, where oxygen is more plentiful. The material within the crevice acts as the anode, and the exterior material becomes the cathode. 

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