Effect of Constant Time Aging Treatment in the Temperature range 100 - 450 degrees C on the Corrosion of Aluminum Alloy 6061

Practices that result in changes in the type or volume fraction of the microstructure constituents of the alloys can affect the susceptibility of these alloys to corrosion. This work was intended to study the effect of constant aging time (24 hrs) in the temperature range 100 - 450 degrees C on the corrosion characteristics of 6061 aluminum alloy, (Al-Mg-Si alloy) containing 0.22 wt% Cu. The investigation was performed by applying potentiodynamic polarization technique in neutral deaerated 0.5 % M NaCl solution. Analysis of the polarization curves was used to determine the effect of different aging temperatures on corrosion characteristics of the alloy. It was found that specimens aged at 210 degrees C exhibited maximum values of I-corr and cathodic current densities, maximum noble shift in E-corr and minimum passivity compared to the specimens aged at 350 and 450 degrees C. Furthermore, aging for 24 hours at 100 degrees C caused less noble Ecorr, higher passivity region and nobler E-br compared to specimens aged at 210 degrees C. These results were discussed in relation to changes in the type and / or weight fraction of the precipitates formed during the aging treatments.