Study on the evaluation of localized corrosion of 2024T3 aluminum alloy with EIS

In this study, the evaluation of localized corrosion of 2024T3 aluminum alloy was performed by electrochemistry impedance spectroscopy (EIS) by time domain method, alternating immersion test, optical microscope and statistic method. The result of EIS by time domain method can enable nondestructive, quantitative and fast localized corrosion evaluation by measuring the reciprocal low frequency impedance (1/Rd) of the samples. 1/Rd and maximum corrosion depth have similar statistical distribution and time-dependent growth. At the same test period, both 1/Rd and maximum corrosion depth were consistent with the Gumbel distribution law. The dynamic variation curve of the 1/Rd and maximum corrosion depth versus the test period were both somewhat of S shape. In order to make the simulation, the dynamic variation curve of 2024T3 Al alloy must be divided into two stages to treat the data, i.e. pitting and intergranular corrosion (Sigmoidal curve) and exfoliation (line). Quantitative relation between the 1/Rd and maximum corrosion depth had been established.