Effects of Three-Step Aging on Microstructure and Stress Corrosion Cracking of 7N01 Aluminum Alloys

Abstract

The precipitation of 7N01 alloy after three-step ageing treatment at 65°C, 100°C and 150°C has been investigated. The SAED results show that at 65°Cpre-aging the GPI zones were precipitated from the quenched solid solution and aging at 150°C results in evolution of the GPI zones formed during under ageing into the η’ phase. It was found that compared with the two-stage aging(T74) and T6 aging, pre-aging at 65°C significantly increased number density of η’ phase. The modified microstructure results in tensile properties comparable to that of the T6 temper, but with significantly improved the resistance of stress corrosion cracking performance.