The sensitization issue of AA5083 alloy and thus resulting intergranular corrosion (IGC) issue always restrict its wide application in the marine and transportation fields. Whether deeply realizing the sensitization mechanism or developing the desensitization method, the key priority is to precisely evaluate the IGC susceptibility. Therefore, this paper aims to compare various IGC evaluation methods and thus develops an improved IGC depth evaluation method based on GB/T 7998-2023 to realize the more rapid and informative evaluation of IGC.
Various IGC evaluation methods, including etching by H3PO4, electrochemical measurements, hardness tests, nitric acid mass loss test and IGC depth test, were compared to evaluate AA5083 alloy with different sensitization levels.
During the optimization of GB/T 7998-2003 standard, it is found that the galvanic corrosion effect between test surface and side surface could be eliminated by sealing the specimens with only the exposure of test area to IGC testing solution. Furthermore, the grain detachment issue was improved by optimizing the ratio of surface area to solution volume and resolved by reducing the IGC immersion time after fixing the ratio of surface area to solution volume. The obtained IGC depth correlates properly with the degree of sensitization obtained by ASTM G67-2018 standard.
IGC depth test based on GB/T 7998-2023, both achieving quantitative evaluation of IGC susceptibility and gaining the rich localized corrosion information, was optimized in this investigation to precisely evaluate the IGC susceptibility of AA5083 alloy plate in a more rapid and informative method.
