Abstract: In this article, alternate immersion tests were applied to bare 2024T3 alloy. Maximum corrosion depth was measured to evaluate the severity of corrosion. Since localized corrosion is a stochastic phenomenon, a statistic method was also used to deal with the data. The results showed that the maximum corrosion depth was consistent with the Gumbel distribution law. For certain area of the specimen, the dynamic variation curve of the maximum corrosion depth vs the test period must be divided into two stages to treat the data, i.e. pitting (sigmoidal curve) and exfoliation ( line), in order to make the simulation. The relationship among the maximum depth, the area and the test time was established. A new life prediction method for natural environmental service was proposed: according to the area of the object, the corrosion loss allowance, accelerated coefficient of alternate immersion test and the above function, the life of bare LY12CZ aluminum alloy can be predicted.

Key words: aluminum alloy, cor rosion, st atistic analysis, dynamics law, life pr ediction