Study on the accelerated corrosion testing method for rapidly evaluating atmosphere corrosion of Mg alloy

Abstract

Mg alloys are prone to corrosion even in an atmospheric environment, and the reliable accelerated corrosion testing methods are essential for effectively evaluating their corrosion resistance. The Cyclic Salt Spray Test, consisting of the alternation of salt spray, wetting and drying, was designed and optimised in this investigation based on the atmospheric corrosion behaviour of AZ80 and EW75 Mg alloys in Shenyang atmospheric environment as a baseline. The results indicate that after Cyclic Salt Spray Test 2# (a mixed solution of 0.03 mol/L Na₂SO₄ and 0.00375 mol/L CaCl₂, with one cycle of 2 h and total test duration of 5 d), the AZ80 Mg alloy is prone to pitting corrosion, while the EW75 Mg alloy tends to experience uniform corrosion, which are consistent with the corrosion images and weight loss variations of EW75 and AZ80 Mg alloys exposed to actual atmospheric environment. In the actual testing, one cycle of 2 h with longer total last durations can be used. This consistency validates the reliability of Cyclic Salt Spray Test for the rapid characterisation of the atmospheric corrosion of Mg alloys.