Abstract:The corrosion resistance of Al-Zn-Mg alloy subjected to different times in flame rectification was investigated based on the exfoliation corrosion test. The results indicate that the flame rectification deteriorates the exfoliation corrosion resistance of Al-Zn-Mg alloy. The corrosion resistance of Al-Zn-Mg alloy is ranked in the following order: base metal>two times>three times>one time of flame rectification. The exfoliation corrosion behavior was discussed based on the transformation of precipitates at grain boundaries and matrix. With increasing the number of times in flame rectification, the precipitate-free zones disappeared and the precipitates experienced dissolution and re-precipitation. The sample was seriously corroded after one time of flame rectification, because the precipitates at grain boundaries are more continuous than those in other samples.

Key words: Al-Zn-Mg alloy; flame rectification; exfoliation corrosion; re-precipitation