某型航空发动机工作264 h后, 一件材料为1Cr18Ni9Ti钢的空气管在钎焊圆根区出现了断裂; 通过观察失效空气管断口的宏观、微观形貌,以及对空气管进行化学成分分析,对空气管进行强度校核计算, 确定了空气管断裂的性质和原因, 并提出了改进措施。结果表明: 空气管的断裂性质为疲劳断裂, 疲劳扩展应力较小; 疲劳裂纹的萌生主要与空气管在装配过程中存在较大的装配应力有关; 提高装配质量可有效预防空气管的断裂。

After 264 h working, an air pipe made of 1Cr18Ni9Ti in an aero engine cracked around brazing root zone. Through observating the macro/micro morphology of the fracture, analyzing the chemical composition of the air pipe, calculating the strength of the air pipe, the characteristics and causes of fracture were confirmed, and the improvement measure was given. The results show that the characterisitcs of the fracture of the air pipe was fatigue fracture and the fatigue extension stress was relatively small. The large assembly stress during assembly process was the main cause of the fatigue crack initiation. Improving assembly quality can effectively prevent the fracture of air tube.