The microstructure of 2624-T39 aluminum alloy was analyzed by means of metallographic (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The effects of different microstructure characteristics on the tensile properties and fatigue crack growth rate of 2624-T39 aluminum alloy were studied. Results showed that the grain size of the alloy was a typical fiber structure along the rolling direction, and the main second phase was the Al 2 CuMg phase. The grain size of the alloy had an obvious influence on the fatigue crack growth rate, and the alloy showed a lower fatigue crack growth rate due to the larger grain size. The crack initiation zone on the fracture surface of alloys with lower fatigue crack growth rate was relatively rough, the crack propagation zone had obvious fatigue striations, and the transient fracture zone had a large number of smaller dimples.

中文翻译：

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2624-T39铝合金不同晶粒尺寸疲劳裂纹扩展行为

采用金相（OM）、扫描电镜（SEM）和透射电镜（TEM）对2624-T39铝合金的显微组织进行了分析。研究了不同组织特征对2624-T39铝合金拉伸性能和疲劳裂纹扩展速率的影响。结果表明，合金晶粒沿轧制方向呈典型的纤维结构，主要的第二相为Al 2 CuMg相。合金的晶粒尺寸对疲劳裂纹扩展速率有明显的影响，由于晶粒尺寸较大，合金表现出较低的疲劳裂纹扩展速率。疲劳裂纹扩展速率较低的合金断裂表面裂纹萌生区较为粗糙，裂纹扩展区有明显的疲劳条纹，