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用四点弯曲试验法测定机匣材料ZL114A铝合金的疲劳强度,通过光学显微镜和扫描电镜对疲劳断口形貌的观察以及对断口的成分分析,研究了疲劳裂纹的形核和扩展特征。结果表明,在2×106循环次数下,ZL11A铝合金的疲劳强度为(150±73)MPa;样品断口具有典型的疲劳断口特征,断口处Si含量偏高,疲劳裂纹在共晶Si与基体界面处形核并沿此界面扩展。
Fatigue strength of the casing material ZL114A aluminum alloy was measured by four-point bending test. The appearance of fatigue fracture and the composition of the fracture were observed by optical microscope and scanning electron microscope. The nucleation and propagation characteristics of fatigue crack were studied. The results show that the fatigue strength of ZL11A aluminum alloy is (150 ± 73) MPa at 2 × 106 cycles. The fracture surface of the sample has typical fatigue fracture characteristics with high Si content at the fracture surface. The fatigue crack at the interface between eutectic Si and matrix At the nucleation and expansion along the interface.