Corrosion Behavior of 7475 High-strength Aluminium Alloy in Marine and Rural Atmosphere Environments

YANG Xiao-kui, ZHANG Lun-wu, HU Bin, ZHANG Shi-yan, LIU Ming, XIANG Yun-liang, XIANG Jiang-tao, MU Xian-liang, LUO Lai-zheng

Surface Technology ›› 2019, Vol. 48 ›› Issue (1) : 262-267.

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Surface Technology ›› 2019, Vol. 48 ›› Issue (1) : 262-267. DOI: 10.16490/j.cnki.issn.1001-3660.2019.01.034
Surface Failure and Protection

Corrosion Behavior of 7475 High-strength Aluminium Alloy in Marine and Rural Atmosphere Environments

  • YANG Xiao-kui1, ZHANG Lun-wu1, HU Bin1, ZHANG Shi-yan1, XIANG Yun-liang1, XIANG Jiang-tao1, MU Xian-liang1, LUO Lai-zheng1, LIU Ming2
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Abstract

The work aims to investigate the effect of marine and rural atmosphere environments on corrosion behavior of 7475 high-strength aluminium alloy, and provide the support for the environment worthiness design of 7475 high-strength aluminium alloy. A 36-month outdoor exposure test was carried out to 7475 high-strength aluminium alloy in Wanning and Beijing atmosphere environment test sites and the atmospheric corrosion kinetics law of 7475 high-strength aluminium alloy in two Chinese typical atmosphere environment was investigated by dint of the weight loss. The micro-morphology and the composition of the rust of 7425 high-strength aluminium alloy were studied by the environmental scanning electron microscope (ESEM), metallographic microscope and X-ray photoelectron spectroscopy (XPS). The atmospheric corrosion rate of 7475 high-strength aluminium alloy exposed in two atmosphere environments exhibited the same change law. The corrosion rate developed rapidly, then decreased with the prolongation of exposure time, and finally came to the stable stage of corrosion expansion. 7475 high-strength aluminium alloy exposed in marine atmosphere environment for 36 months exhibited obvious pitting corrosion, and the corrosion product were mainly composed of AlCl3, Al(OH)3 and Al2O3. The corrosion on the surface of 7475 high-strength aluminium alloy exposed in rural atmosphere environment was very slight and only small and shallow corrosion pits appeared on very few surface. In rural atmosphere and marine environments, the atmospheric corrosion kinetics of 7475 high-strength aluminium alloy follows the power function. Compared with rural atmosphere environment, 7475 high-strength aluminium alloy exhibited the strong corrosion susceptibility in marine atmosphere environment.

Key words

7475 high-strength aluminium alloy; ocean corrosion; rural atmosphere; corrosion product; corrosion behavior

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YANG Xiao-kui, ZHANG Lun-wu, HU Bin, ZHANG Shi-yan, LIU Ming, XIANG Yun-liang, XIANG Jiang-tao, MU Xian-liang, LUO Lai-zheng. Corrosion Behavior of 7475 High-strength Aluminium Alloy in Marine and Rural Atmosphere Environments[J]. Surface Technology. 2019, 48(1): 262-267
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