Properties degradation and atmospheric corrosion mechanism of 6061 aluminum alloy in industrial and marine atmosphere environments

The atmospheric corrosion behavior of 6061 aluminum alloy exposed in industrial and marine atmosphere environments for 36 months has been investigated by weight loss test, tensile strength test, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and optical microscope. The results of weight loss and tensile strength showed that, compared with industrial atmosphere environment, 6061 presented higher corrosion susceptibility in marine atmosphere environment. XPS analysis indicated that the major constituents of corrosion products formed in industrial atmosphere environment were aluminum hydroxide, aluminum oxide, and aluminum sulfate. In marine atmosphere environment, corrosion products mainly contained aluminum chloride, aluminum hydroxide, and aluminum oxide. Surface morphologies analysis revealed that the corrosion products formed in industrial atmosphere environment were agglomerated and uneven. The corrosion products formed in marine atmosphere environment presented polygon shape, and revealed some broad cracks. Cross-section morphologies analysis manifested that 6061 suffered pitting attack in both types of atmosphere environments, and the intensity of pitting attack in marine atmosphere environment was much more serious than that in industrial atmosphere environment.