Effect of plasma electrolytic oxidation treatment on the corrosion and stress corrosion cracking behaviour of AM50 magnesium alloy

The effect of a silicate-based plasma anodization treatment on the corrosion and stress corrosion cracking behaviour of a cast AM50 magnesium alloy was studied. Electrochemical tests revealed the beneficial effect of the plasma electrolytic oxidation (PEO) in improving the corrosion resistance of the alloy. Although the coating had provided an improved resistance to stress corrosion cracking in this test environment at a nominal strain rate of 10−6 s−1, it could not completely eliminate the SCC susceptibility of the alloy. Cracking of the coating under conditions of straining was found to be the reason for SCC of PEO-coated alloy.