Corrosion behavior of 7075 and 2A12 aluminum alloys in different water environments

Abstract

The corrosion of 7075 and 2A12 aluminium alloys are studied in three types of water, including freshwater lake water, salt lake water and saline lake brine in the Qinghai-Tibet Plateau region. The samples are immersed into the different water for different time, which are divided into four types of 30d, 60d, 90d and 120d. After undergoing dry and wet cycle immersion corrosion under natural conditions, it can be concluded that the two aluminum alloy samples have more serious corrosion in freshwater lakes, and 2A12 aluminum alloy is more corrosion resistant than the 7075 aluminum alloy. The corrosion is mainly pitting, accompanied by crevice corrosion and galvanic corrosion. Cl- can pass through the passivation film on the surface of the samples to form pitting pits, while the dissolved Al3+ in the matrix and SO42- in the water can form stable Al2(SO4)3 ∙ χH2O, which plays a certain protective role for the sample.