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采用光学显微镜、扫描电镜、透射电镜以及疲劳性能测试等手段,研究了国产2E12-T3和进口2524-T3合金薄板微观组织和疲劳裂纹扩展性能。结果表明,国产2E12-T3与进口2524-T3合金化学成分相近,在显微组织方面,2E12-T3合金晶粒相对于进口2524-T3合金的纤维状晶粒组织明显细小、均匀,发生了更大程度的再结晶,两者基体内均分布有少量粗大Al2CuMg相和富Fe相,2E12-T3晶内存在略多的中等尺寸Al20Cu2Mn3棒状粒子;在力学性能方面,国产2E12-T3合金抗拉强度、屈服强度和疲劳裂纹扩展速率都明显高于进口2524-T3铝合金,疲劳断口皆呈典型3个区域,裂纹萌生区,前者较平坦而后者相对粗糙,裂纹扩展区皆有明显的疲劳辉纹,辉纹间距分别为0.65和0.35μm,瞬断区,后者具有数量更多、尺寸更小的韧窝。着眼于材料的组织特征,导致2E12-T3和2524-T3铝合金力学性能差异的主要原因可能是由于两者的晶粒组织特征不同。
The microstructure and fatigue crack propagation properties of domestic 2E12-T3 and imported 2524-T3 alloy sheets were investigated by means of optical microscope, scanning electron microscope, transmission electron microscope and fatigue test. The results show that the chemical composition of domestic 2E12-T3 and imported 2524-T3 alloy is similar. In terms of microstructure, the grain structure of 2E12-T3 alloy is obviously smaller and more uniform than the imported 2524-T3 alloy, A large amount of recrystallization, a small amount of coarse Al2CuMg phase and Fe-rich phase are distributed in both of the matrix and a little more middle-sized Al20Cu2Mn3 rod-like particles exist in the 2E12-T3 crystal. In terms of mechanical properties, the tensile strength of the domestic 2E12-T3 alloy , The yield strength and the fatigue crack growth rate are significantly higher than the imported 2524-T3 aluminum alloy, the fatigue fracture is typical of three regions, the crack initiation zone, the former is relatively flat and the latter is relatively rough, the crack growth zone has obvious fatigue pattern , With a pattern spacing of 0.65 and 0.35 μm, respectively, in the snap zone, the latter having a larger number of dimples of smaller dimensions. Focusing on the tissue characteristics of the materials, the main reason for the difference in mechanical properties of 2E12-T3 and 2524-T3 aluminum alloys may be due to the different grain-structure characteristics of the two.