Influence of Interfacial Stress Produced by MAO on Electrochemical Corrosion and Stress Corrosion Cracking Behavior in 7075 Aluminum Alloy

The interfacial stresses of micro arc oxidation (MAO) coated 7075 Al alloy foil samples were measured by a deflection method. The results showed that compressive stresses were generated on the substrate-coating interface of the samples coated for different oxidation times. Electrochemical tests and slow strain rate tensile tests in a 3.5 wt% sodium chloride solution indicated that the compressive stress played a positive role in corrosion and stress corrosion cracking (SCC) resistance. The findings of this work indicated that the MAO coating can not only act as a protective layer to hinder corrosive solution, but also the compressive stress generated during MAO process can offset part of the external stress and reduce the hydrogen penetration during SCC.