(1. 宁夏大学 机械工程学院，银川 750021；
2. 宁夏大学 宁夏智能装备CAE重点实验室，银川 750021)
摘 要: 2024铝合金常用于航空工业中，在海洋大气环境下服役时受到盐水环境的腐蚀，会显著缩短结构的使用寿命。本文以2024铝合金为研究对象，通过力学试验、电化学分析和扫描电子显微镜等分析手段，探讨2024铝合金在不同腐蚀时间下的力学性能变化、电化学腐蚀机理与断口裂纹演化特征。结果表明：2024铝合金在EXCO溶液中腐蚀0~9 h后，其腐蚀形貌表现为点蚀和晶间腐蚀的混合腐蚀模式；随着腐蚀时间的延长，腐蚀速率加快，蚀坑尺寸逐渐增大。腐蚀坑对2024铝合金的力学性能有较大影响。腐蚀时间在1 h内时，蚀坑导致的应力集中使试样的硬度、抗拉强度和伸长率迅速下降，蚀坑萌生的裂纹源诱发疲劳寿命显著下降69%；腐蚀时间超过1 h时，蚀坑在深度方向的缓慢扩展削弱了应力集中的影响，使硬度、抗拉强度、伸长率及疲劳寿命下降趋势减缓。2024铝合金在EXCO溶液中腐蚀后的疲劳断裂为沿晶断裂、解理断裂和韧性断裂的混合断裂模式。
关键字: 腐蚀；疲劳；电化学；裂纹；2024铝合金
（1. School of Mechanical Engineering, Ningxia University, Yinchuan 750021, China;
2. Ningxia Key Laboratory of Computer Aided Engineering Technology for Intelligent Equipment, Ningxia University, Yinchuan 750021, China）
Abstract:The 2024 aluminum alloys are commonly used in the aerospace industry and are subject to corrosion from salt water environments during service, which can significantly reduce the service life of the structure. In this paper, the mechanical property changes, electrochemical corrosion mechanism and fracture crack evolution of 2024 aluminum alloy at different corrosion time were investigated by mechanical tests, electrochemical analysis and scanning electron microscope analysis. The results show that the corrosion morphology is a mixed corrosion pattern of pitting and intergranular corrosion when the immersion time is 0-9 h. As the corrosion time increasing, the corrosion rate accelerates and the size of the corrosion pit gradually increases. The corrosion pits have a significant effect on the mechanical properties of 2024 aluminum alloy. The stress concentration caused by the corrosion pits makes a rapid decrease in hardness, tensile strength and elongation of the specimens when the immersion time is 0-1 h, and there is 69% reduction in fatigue life due to crack sources sprouting from the corrosion pits. When the corrosion time is more than 1h, the slow expansion of the corrosion pits in depth direction weakens the effect of stress concentration, leading to a slowing trend of hardness, tensile strength, elongation and fatigue life reduction. The fatigue fracture of 2024 aluminum alloy after corrosion in EXCO solution is a mixed mode of intergranular fracture, cleavage fracture and ductile fractures.
Key words: corrosion; fatigue; electrochemistry; crack; 2024 aluminum alloy
