Abstract: Effects of shot peening strengthening, solution strengthening and shot peening strengthening+solution strengthening on the salt spray corrosion resistance of as-aged 2024 aluminum alloy were studied. The results show that there are numerous secondary phase particles in the primitive specimen microstructure, with the longest particle size of about 83 μm. After solution treatment, some of the secondary phase particles dissolve in the matrix, and the remained particle size is reduced to 17 μm. After the combined treatment of shot peening and solution treatment strengthening, almost all of the secondary phase particles near the surface are dissolved. When the salt spray corrosion test time is 3 h, the diameter of the corrosion pit of the primitive specimen is approximately ø90 μm, the corrosion pit diameter of the shot peening and solution strengthened specimen is about ø50 μm, the corrosion depth of the shot peening specimen is about 38.75 μm, while the corrosion depth of the shot peening and solution strengthened specimen decreases to 12.5 μm. This indicates that the combined treatment of shot peening and solution treatment strengthening contributes to dissolve the second phase particles, improves the uniformity of material structure and composition, and thereby enhances the corrosion resistance of aluminum alloys.

Key words: salt spray corrosion, secondary phase particles, solution treatment, intergranular corrosion, corrosion pits