Abstract: Mechanical properties and corrosion resistance of the double-stage aged 7A41 aluminium alloy were tested by the test methods of tensile properties at room temperature, stress corrosion properties and salt spray corrosion properties, respectively. Microstructure of the alloy and the microscopic morphology of tensile fracture were characterized by metallographic microscope, scanning electron microscope(SEM) and transmission electron microscope(TEM). The results show that the tensile strength, yield strength and elongation of the alloy in T6 state are 505 MPa, 474 MPa and 16.3%, respectively. The stress corrosion resistance is excellent, the stress corrosion sensitivity coefficient is 3.98%, and the salt spray corrosion rate of the alloy is 0.0914 mm/y. TEM observation and analysis show that the nano-scale precipitates are uniformly dispersed in the double-stage aged 7A41 alloy grains, and a large number of discontinuous precipitates are distributed on the grain boundaries. The size of the precipitates is 20-50 nm. The discontinuous precipitates effectively hinder the path of intergranular corrosion of the alloy and the good microstructure characteristics ensure the comprehensive properties of the alloy.

Key words: 7A41 aluminium alloy, mechanical properties, stress corrosion, salt spray corrosion