二氧化硫复合盐雾环境下2024-T351铝合金应力腐蚀开裂

通过SO₂复合盐雾试验模拟工业污染海洋大气环境,结合有限元模拟分析、扫描电镜/能谱仪、光电子能谱分析等技术研究2024-T351铝合金在弹性应力区间的应力腐蚀开裂行为.结果表明:应力腐蚀开裂行为优先发生在2024-T351铝合金C型环的顶部应力集中区域;疏松的腐蚀产物层的形貌经历了由细棒状、团絮状到板块状的变化;试验6 h就可以监测到裂纹,进行到480 h的时候有贯穿裂纹形成,720 h的时候试样完全断裂;裂纹为穿晶和沿晶混合机制,主裂纹以穿晶机制沿C型环法线扩展,二次裂纹沿晶界扩展. 

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.