The effect of different aging processes on the mechanical and intergranular corrosion properties of 7A85 high strength aluminum alloy were investigated using the methods of tensile test, conductivity test, intergranular corrosion test and metallographic microscope observation etc.. The results indicate that when the aging temperature is in the range of 110 similar to 140 degrees C, the conductivity of the 7A85 aluminum alloy increases with increasing aging temperature, intergranular corrosion depth decreases gradually and the intergranular corrosion resistance of the alloy is improved. The alloy shows first peak hardness at aging time of 30 h and aging temperature of 120 degrees C. At the aging temperature of 120 degrees C, the conductivity increases and the intergranular corrosion depth of the alloy decreases with aging time extending, that is to say, the intergranular corrosion susceptibility of the alloy decreases with increasing aging time. After the alloy is treated with the aging process of 470 degrees C/2 h + 120 degrees C/30 h, the tensile strength of 710.3 MPa, yield strength of 655.46 MPa, elongation rate of 11.25%, conductivity of 30.7% IACS, and average intergranular corrosion depth of 0.100 mm can be reached. The heat treatment system can make the alloy maintaining good mechanical properties as well as high intergranular corrosion resistance.

7A85 aluminum alloy; aging treatment; microstructure; mechanical properties; intergranular corrosion

Taiyuan University of Technology; Hunan University