Effect of heat treatment on stress corrosion cracking, fracture toughness andstrength of 7085 aluminum alloy
(1. Institute of Light Alloy, Central South University, Changsha 410083, China;
2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China)
2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China)
Abstract: The influences of heat treatment on stress corrosion cracking (SCC), fracture toughness and strength of 7085 aluminum alloy were investigated by slow strain rate testing, Kahn tear testing combined with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the fracture toughness of T74 overaging is increased by 22.9% at the expense of 13.6% strength, and retrogression and reaging (RRA) enhances fracture toughness 14.2% without reducing the strength compared with T6 temper. The fracture toughness of dual-retrogression and reaging (DRRA) is equivalent to that of T74 with an increased strength of 14.6%. The SCC resistance increases in the order: T6<RRA<DRRA≈T74. The differences of fracture toughness and SCC were explained on the basis of the role of matrix precipitates and grain boundary precipitates.
Key words: 7085 aluminum alloy; heat treatment; stress corrosion cracking; fracture toughness