(1. 寧夏大學 機械工程學院，銀川 750021；
2. 寧夏大學 寧夏智能裝備CAE重點實驗室，銀川 750021)
摘 要: 2024鋁合金常用于航空工業(yè)中，在海洋大氣環(huán)境下服役時受到鹽水環(huán)境的腐蝕，會顯著縮短結構的使用壽命。本文以2024鋁合金為研究對象，通過力學試驗、電化學分析和掃描電子顯微鏡等分析手段，探討2024鋁合金在不同腐蝕時間下的力學性能變化、電化學腐蝕機理與斷口裂紋演化特征。結果表明：2024鋁合金在EXCO溶液中腐蝕0~9 h后，其腐蝕形貌表現(xiàn)為點蝕和晶間腐蝕的混合腐蝕模式；隨著腐蝕時間的延長，腐蝕速率加快，蝕坑尺寸逐漸增大。腐蝕坑對2024鋁合金的力學性能有較大影響。腐蝕時間在1 h內時，蝕坑導致的應力集中使試樣的硬度、抗拉強度和伸長率迅速下降，蝕坑萌生的裂紋源誘發(fā)疲勞壽命顯著下降69%；腐蝕時間超過1 h時，蝕坑在深度方向的緩慢擴展削弱了應力集中的影響，使硬度、抗拉強度、伸長率及疲勞壽命下降趨勢減緩。2024鋁合金在EXCO溶液中腐蝕后的疲勞斷裂為沿晶斷裂、解理斷裂和韌性斷裂的混合斷裂模式。
關鍵字: 腐蝕；疲勞；電化學；裂紋；2024鋁合金
（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
