Crevice Corrosion of Some Ni-Cr-Mo-Fe Alloys in Laboratory Tests

Results were obtained for six alloys, evaluated in the laboratory for crevice corrosion resistance. Two methods were used: (1) direct observation of corrosion damage in several electrolytes and (2) electrochemical determination of polarization curves. Results showed the ratings of the alloys in the order of decreasing resistance using both methods. In the direct crevice corrosion tests, it was found that the crevice size was important, especially for the more resistant alloys. Some scatter was found in those results. The polarization data provided more detail of corrosion behavior over a wide range of potential; therefore, the electrochemical test was considered a superior tool in alloy screening and development. Neither method, at present, can predict exact field performance.