Influence of Long-Term Immersion Tests on the Electrochemical Corrosion Behavior of an Ultrafine-Grained Aluminum Alloy

The long-term corrosion resistance of commercially pure aluminum (AA1050) processed by equal channel angular pressing (ECAP) was evaluated in a saline environment. The study compared the microstructure and corrosion behavior of ECAP-processed samples in route A with 1X, 4X, and 8X passes to an annealed sample using a 3.5% NaCl solution. Characterization techniques, including optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and electrochemical impedance spectroscopy (EIS), were employed. Results indicate that ECAP processing enhances the passive corrosion resistance compared to the undeformed sample. However, the improvement in corrosion resistance did not consistently increase with the number of ECAP passes. Factors such as the distribution of high- and low-angle grain boundaries, dislocation density, and fragmentation and redistribution of coarse dispersoid particles play a significant role in the corrosion behavior post-ECAP. Additionally, findings suggest that long-term immersion tests are required to obtain a more reliable electrochemical response.