Effect of aging time at low aging temperatures on the corrosion of aluminum alloy 6061

The effect of heat treatment in the underaged, peak aged and overaged conditions in the temperature range 140–225 °C on the corrosion characteristics of Al–Mg–Si–Cu alloy (AA6061) was investigated. Potentiodynamic polarization testing in neutral NaCl solution and immersion testing in acidified NaCl solution were applied to investigate the corrosion behavior of the alloy. The results showed significant dependence of the dominant corrosion form and the electrochemical corrosion parameters on the aging conditions. Maximum changes were noted for the peak aged condition. The results were discussed in terms of changes in precipitate type, size, volume fraction and distribution.

► The alloy composition and final heat treatment may together affect the resistance of aluminum to certain types of corrosion.
► The aging treatment was carried out in the temperature range 140–225 °C for time periods up to 20,100 min.
► Potentiodynamic polarization test and the immersion corrosion test methods were applied during this investigation.
► The results showed significant dependence of the electrochemical corrosion characteristics and the mode of corrosion on the aging condition.
► The results were discussed in terms of changes in precipitate type, size, volume fraction and distribution.