温度对LY12CZ铝合金疲劳短裂纹扩展行为的影响

摘要

LY12CZ铝合金在飞机结构中广泛应用，由于其在高温下软化倾向小，因此可以用作受热部件。随着温度的提高，材料的物理性质会发生改变，引起材料抗疲劳性能退化，缩短结构的服役寿命。利用扫描电镜原位技术对不同温度下铝合金的疲劳行为进行研究。试验结果表明温度会影响铝合金疲劳短裂纹的扩展。基于短裂纹行为，提出了一种评价温度机械疲劳载荷共同作用下的铝合金短裂纹行为方法。%　　Aluminum alloy LY12CZ is widely applied in aviation industry. For the low softening tendency under high temperature, it can be used in structures that will serve in high temperature environment. But with temperature increasing, the physical property of the material will suffer from degradation, and the service life will be reduced. The fatigue behavior of the material under various elevated temperature was studied using SEM in-situ technology. The result indicated that elevated temperatures do have impacts on fatigue crack propagation. Based on the micro-cracking investigation, a method to evaluate the fatigue crack growth under combined effect of elevated temperature and mechanical fatigue loads was put forward.