Although natural environmental tests were one realistic and accurate method for studying and evaluating the equipment corrosion life, but it had to be cost so many time and money for high-reliability and long-life products, which could not be accepted and carried out generally. Therefore, the artificial accelerated corrosion tests were developed to overcome the huge cost problem of time and money, such as cycle infiltration test, salt-spray test and so on. The simulation and relation characteristics to contrast with the outdoor results were key factors for designing and evaluating the accelerated testing methods, which could be considered as follows, (a) alternating wet and dry process of specimen surface; (b) corrosion kinetics laws; (c) morphology, composition and structure of corrosion products; (d) electrochemical properties and mechanisms of corrosion process. In this article, to study the corrosion behavior and mechanism of 2A12 aluminum alloy under the interior simulated and strengthened corrosion environment, and establish the accelerated test methods for evaluating the corrosion life of aluminum alloy. Utilizing the designed accelerated corrosion environment testing spectrum, accelerated corrosion tests by cyclic salt-spraying were performed to simulate marine atmospheric environment effect. By means of testing methods of scanning electron microscope, X ray diffraction, electrochemical and so on, the corrosion performance of specimens after different exposure time, such as corrosion weight loss, corrosion morphology, corrosion products composition, polarization curves and impedance spectroscopy were characterized. Accelerated corrosion behavior and mechanism of aluminum alloy were analyzed and concluded. With the corrosion exposure time extension, 2A12 specimen corrosion weight loss conformed to power function law with the expression as D=1.662t1.061, and corrosion rate appeared the variation trend of reducing briefly, then increasing rapidly and then declining gradually. Corrosion morphology appeared that corrosion products distributed from uniform to concentrated and outstanding, and fallen off from the specimen surface in anaphase. The chemical constituents of corrosion products mainly contained Al2O3, which was almost the same with chemical process by corrosion mechanism analysis. The results of polarization curve fitted by Tafel was indicated that corrosion potential appeared a steady and slowly decreasing trend (‒0.509-‒0.392 V), corrosion current density appeared a tendency for fluctuation to increase and then decrease (0.271-0.882 A/cm2); Electrochemical impedance spectroscopy performanced for one capacitive loop in high-frequency zone, and the radius of capacitive loops presented a trend of decrease, increase and decrease to stable. The results of EIS fitted by equivalent circuit was indicated that corrosion product film resistance appeared a trend of increase, decrease, increase and decrease, polarization resistance appeared a trend of a tendency to decrease and then increase. The interior accelerated corrosion testing was established to simulate and study the marine atmospheric environment corrosion of high-strength aluminum alloy. Experimental results showed that the corrosion accelerated effect was significant for high-strength aluminum alloy by cyclic salt-spray test, the corrosion behavior and mechanism of aluminum alloy could be characterized more comprehensively from the point of view of corrosion kinetics, corrosion morphologies, corrosion products constitutes and electrochemical characteristics, which could provide conditions for investigating the simulation and correlation of accelerated corrosion test. © 2022, Chongqing Wujiu Periodicals Press. All rights reserved.
