The effect of homogenization temperature on the corrosion resistance of extruded 7050 Al-alloy bars

The homogenization time is decreased from 28 h to 6 h by using high-temperature homogenization heat treatment. With increasing of the holding time, the content of intergranular phase decreases quickly at first. When the holding time is more than 6 h, the content of intergranular phase keeps unchanged, and the area fraction of residual intergranular phase is 0.5%, lower than that (0.64%) of the two-step homogenization process. The mechanical properties of the extruded bars heat-treated by the high-temperature homogenization and the two-step homogenization heat treatment are almost the same. In the accelerated corrosion experiments, the maximum intergranular corrosion depth in the direction of perpendicular and parallel to the bar axis heat-treated by the high-temperature homogenization heat treatment are decreased by 43% and 60%, respectively, compared with that heat-treated by the two-step homogenization heat treatment.