Stress corrosion cracking of 2024-T351 aluminum alloy in SO₂ mixed salt spray environment

The stress corrosion cracking of 2024-T351 aluminum alloy was investigated by finite element simulation analysis, scanning electron microscopy/energy dispersive spectrometry, and X-ray photoelectron spectroscopy through SO₂ mixed salt spray test. Results indicate that stress corrosion cracking initiates preferentially at the region of stress concentration of the C-ring top for 2024-T351 aluminum alloy. The morphologies of loose corrosion products change from fine rod-like and flocculent to plate-like. Secondary cracks form in the internal corrosion crack after 6 h, when the corrosion time increases to 480 h, and the fractures and cracks in the surface of the C-ring side penetrate the whole sample. The C-ring sample completely breaks after 720 h. The opening crack propagation is a mixed mode of transgranular and intergranular, while the main cracks extend along the normal of the C-ring and the secondary cracks extend mainly along the grain boundaries.