The resistance of Alloy 22 (UNS N06022) to crevice corrosion in aggressive environments was studied using various modifications of the Tsujikawa-Hisamatsu Electrochemical (THE) technique. THE technique on a creviced specimen involves potentiodynamic polarization to initiate crevice corrosion, holding the specimen at constant current for a period to grow the crevice and then stepping the potential downward until the crevice repassivates. In this work, a new criterion for determining the crevice repassivation potential (ER,CREV) is proposed, i.e., the potential at which the current reaches the passive current measured on the forward scan. This value of ER,CREV is unambiguous, conservative, and more reproducible for Alloy 22 in the solutions studied. Furthermore, this definition allows for a modification of the THE technique that simplifies the measurement and decreases the time of experiment. With this definition, it is possible to use a potentiodynamic-galvanostatic-potentiodynamic approach, which results in similar values of ER,CREV for non-welded and as-welded Alloy 22 specimens in chloride solution. Moreover, ER,CREV was independent of hold current density in the crevice region. THE technique was further modified to allow determination of the crevice repassivation temperature (TR,CREV). TR,CREV values for non-welded and as-welded Alloy 22 specimens were within 5°C. Effects of potentially inhibitive oxyanions in chloride solutions were also evaluated for Alloy 22.

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