Effect of retrogression treatment with different heating rates on microstructure, strength and corrosion behaviors of 7050 alloy

Abstract

In order to achieve the combination of mechanical and corrosion properties for 7050 alloy, a novel retrogression and re-aging regime were proposed in this study. During the retrogression, the pre-aged alloys were heated from room temperature to 190 °C with different retrogression heating rates, and then were cooled quickly for following re-aging treatment. The size of precipitates and the width of precipitation free zones decreased with the increasing retrogression heating rate, the mechanical properties of 7050 alloy were improved, while the corrosion resistance was reduced. When the retrogression heating rate was controlled at 3 °C/min, a good combination of strength and corrosion resistance of 7050 alloys could be obtained. The excellent properties were attributed to the homogeneous distribution of intragranular precipitates (η’) and the coarsening of intergranular precipitates (η) after the novel retrogression and re-aging regime.