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本文用扫描电镜分析了2024—T3510、T8510两种时效状态的拉伸、疲劳和应力腐蚀断口。研究结果表明,时效状态对合金的断裂行为有显著的影响。合金在 T3510状态下,拉伸断口的宏观特征为45全剪切型,其微观特征以剪切面为主。疲劳裂纹的萌生与扩展均呈Ⅰ阶方式(循环切应变方式),断口表面特征为刻面状和锯齿状。应力腐蚀断口表面均为沿晶断裂特征。合金在 T8510状态下,拉伸断口的宏观特征为不典型的正断型,其微观特征主要以 Fe 的杂质相为核心的韧窝机制。疲劳裂纹的萌生与扩展Ⅰ阶、Ⅱ阶方式(循环切应变→循环正应变顺序单一过程),扩展阶段主要为Ⅱ阶方式,断口表面有典型的疲劳条带。应力腐蚀断面主要为解理扇特征。
In this paper, the tensile, fatigue and stress corrosion fracture of 2024-T3510 and T8510 were analyzed by SEM. The results show that the aging state has a significant effect on the fracture behavior of the alloy. In T3510 alloy, the macroscopic feature of tensile fracture is 45-shear type, and its microscopic features are mainly shear. The initiation and propagation of fatigue crack show a first-order mode (cyclic shear strain mode), and the surface features of fractures are serrated and serrated. Stress corrosion fracture surface are intergranular fracture characteristics. In T8510 alloy, the macroscopic feature of tensile fracture is an atypical normal fault, and its microscopic features are mainly dimple mechanism with Fe impurity phase as the core. Fatigue crack initiation and propagation Ⅰ order, Ⅱ mode (cyclic shear strain → cyclic normal strain sequence of a single process), the expansion stage is mainly Ⅱ-order mode, the fracture surface of a typical fatigue band. Stress corrosion section is mainly cleavage fan features.