2013•The Chinese Journal of Nonferrous MetalsRequires access
Effect of aging on corrosion resistance of 7050 aluminum alloy pre-stretching plate
Song Feng-xuan, Zhang Xin-ming, Shengdan Liu, Han Nian-mei, Hua Long
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Abstract
The effects of aging after pre-stretching process on microstructure,hardness,and corrosion resistance of the 7050 aluminum alloy plate were investigated by means of hardness tests,corrosion rate tests,exfoliation corrosion tests,slow strain rate tensile(SSRT) tests,transmission electron microscopy and differential scanning calorimetry(DSC).The results indicate that the peak-aged 7050 aluminum alloy possesses the highest hardness,but its corrosion resistance is poor.The overaging and the retrogression and re-aging treatments lower the hardness,but improve the corrosion resistance of the 7050 aluminum alloy compared with the peak-aging treatment.At the high temperature aging stage of the high temperature and a subsequent low temperature aging,GP zone can be reversed,which is beneficial to the nucleation of η′ and η phases.Consequently,the precipitates within grains become coarser and distribute uniformly,leading to the decrease of hardness.Meanwhile,the precipitates at grain boundaries become coarser and discontinuous resulting in an improved corrosion resistance.