Influence of applied strain on the microstructural corrosion of AlMg2 as-cast aluminium alloy in sodium chloride solution

The corrosion behavior of ISO AlMg2 (AA5052) was studied at the microscale using the Electrochemical Microcell Technique. The influence of plastic deformation on the corrosion resistance of this alloy was also examined. After polishing, pitting at small copper-enriched precipitates and structural etching were observed. After deformation, numerous slip bands were found in grains. After 5.5% plastic strain, the global electrochemical behavior of samples was significantly affected. Pitting potential was decreased in sites containing slip bands or in sites with large strain gradients (measured using microgauges deposited by lithography).

► AlMg2 as-cast alloy undergoes pitting corrosion and structural etching in 0.1 M NaCl solution.
► Pitting corrosion occurred at nano-precipitates enriched in copper.
► Heterogeneous strain field is generated at the microscale under straining conditions.
► Heterogeneous strain field is associated with large dispersion in the pitting potential values.
► Cathodic reactions were increased by one order of magnitude under straining conditions.