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研究激光冲击对航空铝合金LY12CZ紧固孔疲劳特性的影响,孔的直径为d3 mm。利用X射线衍射法测量残余应力,对试件进行疲劳断裂实验,并用扫描电子显微镜(SEM)观察试件疲劳断口的微观特征。结果表明:激光冲击会在紧固孔端面形成残余压应力,冲击试件的疲劳寿命是未冲击的3.5倍。通过断口的观察和比较发现,冲击后试件的疲劳裂纹源于次表层,而不是源于试件表层,冲击后疲劳断口快速扩展区的疲劳条纹间距比未冲击试件疲劳断口快速扩展区的疲劳条纹间距要小。另外,在冲击试件断裂区的韧窝明显比未冲击的要大,这与冲击时材料内发生塑性变形有关。
The impact of laser shock on the fatigue properties of the aluminum alloy LY12CZ fastening hole was investigated. The diameter of the hole was d3 mm. The residual stress was measured by X-ray diffraction, the fatigue fracture of the specimen was observed, and the microscopic characteristics of the fatigue fracture of the specimen were observed by scanning electron microscope (SEM). The results show that the laser shock will form residual compressive stress on the end face of the fastening hole, and the fatigue life of the impact specimen is 3.5 times that of the non-impact specimen. Through the observation and comparison of the fracture, it is found that the fatigue cracks originated from the sub-surface but not from the surface of the specimen after impact. The fatigue stripe spacing of the rapid expansion of the fatigue fracture after impact is higher than that of the fatigue fracture of the non-impact specimen Fatigue stripes spacing to be small. In addition, the dimples in the fracture zone of the impact specimen were significantly larger than those without impact, which was related to the plastic deformation in the material during impact.