Effect of H321 stabilizing treatment on microstructure, hardness, and grain boundary corrosion resistance of 5083 aluminum alloy

In this research, the influence of H321 stabilizing heat treatment on microstructure, hardness, and intergranular corrosion resistance of 1cm thick sheet of AA5083 has been investigated. After 10%, 20%, 30%, and 40% cold rolling of samples, they were all annealed for recrystallization. The processes of rolling and annealing have been repeated until 1.5mm thickness samples were obtained. Then, 30% cold work was applied to them to achieve sheets having 1mm thickness. For stabilizing treatment, samples were put in the heat treatment furnace for 1 and 4 hours in a temperature range of 150°C to 300°C. Then, sensitization treatment was applied to the samples at 150°C for 48h to consider the effect of stabilizing. The results show that the hardness of samples decreases by increasing stabilizing temperature. The optimum stabilizing temperature for samples with 10% to 30% rolling is 220°C to attain the highest corrosion resistance, but this treatment does not improve the sample's corrosion resistance with 40% rolling. In conclusion, the sample with 20% rolling, which stabilized at 220°C, exhibits mass loss of 6 to 9 mg/cm2 and hardness of 100HV in 4h and 110HV in 1h of stabilizing time has the optimum combination of hardness and intergranular corrosion resistance.