Study on Accelerated Corrosion Experiment of Typical Aluminum Alloy in Simulated Tropical Coastal Atmospheric Environment

Aluminum alloys are widely used in the field of marine engineering owing to lightweight and excellent corrosion resistance.However，the complexity and severity of the marine atmospheric environment can lead to serious corrosive damage to aluminum alloy components.The corrosion behavior and regularity of typical aluminum alloy 2A12 and 5A02 under simulated tropical coastal atmospheric environment were studied by indoor cyclic salt spray accelerated test.The corrosion micromorphology， corrosion product composition and electrochemical behavior of samples with different cyclic periods were analyzed and compared with outdoor exposure test.In addition， the correlation between the results of outdoor environmental exposure test and indoor accelerated test was quantitatively analyzed by grey relational method.Results showed that the relationship between corrosion weight loss and time of 2A12 and 5A02 samples conformed to the law of power function.After the test， obvious pitting corrosion occurred on the surface of aluminum alloy， and the corrosion products primarily consisted of Al2O3 and AlO(OH).With the extension of the test time，the pitting degree of aluminum alloy was deepened，and the number and depth of pitting pits increased.Meanwhile，the number and depth of pitting pits on the surface of 5A02 aluminum alloy were lower than that of 2A12 aluminum alloy.The electrochemical impedance fitting results also showed that the corrosion resistance of 5A02 aluminum alloy was better than that of 2A12 aluminum alloy with the increase of cycle acceleration period.By comparing the results of outdoor test and indoor test，it could be concluded that indoor cyclic salt spray acceleration test could simulate the results of outdoor exposure tests well， and reflect the corrosion behavior and law of aluminum alloy well in terms of pitting depth change and weight loss dynamics.However，the simulation correlation would decrease with the extension of exposure time.Overall， this study provides basic test data for optimizing the correlation between indoor accelerated corrosion test and outdoor exposure test of typical aluminum alloys.