Stress corrosion cracking behaviour of a surface-modified magnesium alloy

The effect of plasma electrolytic oxidation (PEO) treatment on the stress corrosion cracking (SCC) of a cast magnesium alloy was assessed. Even though the PEO coating has offered improved corrosion resistance, as evidenced in electrochemical tests, its effect in improving the SCC resistance in ASTM D1384 test solution was only marginal. The SCC behaviour of PEO-coated specimens was attributed to the development of microcracks in the coating, leading to cracking of the substrate under slow strain rate test conditions.