Effect of heat treatment on strength, exfoliation corrosion and electrochemical behavior of 7085 aluminum alloy

The influence of heat treatment on strength, exfoliation corrosion and electrochemical behavior of 7085 aluminum alloy has been investigated by tensile testing, exfoliation corrosion testing, polarization curve and electrochemical impedance spectroscopy (EIS) combined with transmission electron microscope (TEM). The results show that retrogression and reaging (RRA) improved exfoliation corrosion resistance without sacrificing the strength compared to T6 temper. Dual-retrogression and reaging (DRRA) improved exfoliation corrosion resistance equivalent to T74 temper and maintained the strength similar to retrogression and reaging. The high-temperature and the subsequent low-temperature aging (HLA) decreased the strength and corrosion resistance compared to the T6 temper. The trends of corrosion resistance are further confirmed by polarization curve experiment and EIS test. The effect of heat treatment on strength and corrosion resistance is explained by the role of matrix precipitates and grain boundary precipitates, respectively.