Corrosion mechanism of aluminum alloy materials under high corrosion conditions
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Abstract:
With the advantages of low density, low melting point, high specific strength and excellent corrosion resistance, aluminum alloys are widely used in aerospace, construction, shipbuilding and other industries. During service, the surface oxide film of aluminum alloys is susceptible to corrosion by active anions in the environment, causing serious damage to its performance. Therefore, studying the corrosion behavior of aluminum alloys in a highly corrosive environment is very important for engineering material selection. In this work, 6061 aluminum alloy, 2195 aluminum-lithium alloy and 7075 aluminum alloy were taken as the research objects, their corrosion process and mechanical properties in specific corrosive media were analyzed, and their corrosion morphology and mechanical properties in specific corrosive media were investigated. The results show that in the early stage of corrosion, in a corrosive environment with high Cl-, , and - concentrations, the oxide films of the three aluminum alloys undergo pitting corrosion after being damaged by anions, which exposes the matrix of the alloys to the corrosive environment, resulting in electrochemical corrosion. The corrosion of both 6061 aluminum alloy and 2195 aluminum-lithium alloy progresses from pitting corrosion to surface corrosion, while the 7075 aluminum alloy corrosion mode is intergranular corrosion. After corrosion, 6061 aluminum alloy maintains stable strength and plasticity, but the strength and plasticity of 7075 aluminum alloy and 2195 aluminum-lithium alloy are significantly reduced.
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Supported by China Southern Power Grid Major Science and Technology Project (GZKJXM20191302).
