Double-Loop Electrochemical Potentiodynamic Reactivation (DLEPR) is a useful technique to measure the degree of sensitization (DoS) in austenitic stainless steels, as it is fast, nondestructive, and accurate in identifying low to medium DoS. While its use has been well-established for wrought austenitic stainless steels, the same is not true for their cast equivalents. A modified version, with more aggressive conditions in order to more selectively cause reactivation in regions that had residual ferrite from solidification, was tested with cast austenitic stainless steel spanning both UNS J92500 and J92600 compositions. Testing included microstructural evaluation of polished surfaces after the electrochemical tests and DoS measurements. The modified DLEPR consistently measured higher DoS values, but the trends in the data were the same for both versions of the test. Microscopy was more difficult with the modified DLEPR, as the surfaces were more severely corroded, somewhat masking smaller features such as inclusions and twin boundaries.

Subject
Surface finishing, Steel structures, Test methods, Materials, Composition, Microstructure, Corrosion testing, Corrosion attacks, Sensitization, Ports and harbors, Stainless steel, Ferrite, Wrought metals
Keywords:
Corrosion monitoring, Corrosion tests, Stainless steels, Test methods, Electrochemistry, Sulfuric acid
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2021
Association for Materials Protection and Performance (AMPP)
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