Influence of aging conditions of the properties of V91 aluminum alloy

Previously abstracted from original as item 9105-4.6-0068Y. The mechanical and stress corrosion cracking properties of V91 Al alloy (2 magnesium, 0.5 Mn, 4.5 Zn, 0.014 Zr, and not > 1% Cu) were studied after various single- and two-step aging heat treatments. Extruded and forged profiles were aged at 20-200 deg C for varying periods of time. Transmission electron microscopy showed the formation of G--P zones, metastable and stable phases and particle coalescence at varying aging treatments. Single-step aging was not satisfactory in developing strength and corrosion resistance in this alloy. Maximum corrosion resistance was achieved by coalescent aging cycles, and the following two-step cycles were recommended: T1--100 deg C (4-10 h) + 155 deg C (6-12 h); T2--100 deg C (4-10 h) + 170 deg C (4-12 h); and T3--100 deg C (4-10 h) + 180 deg C (3-10 h). Graphs, Photomicrographs.--X-ref.(US).