防喘压力信号管断裂分析

Failure Analysis of Antisurge Pressure Signal Pipe in an Aero-engine

发动机防喘压力信号管多次于钎焊位置断裂。采用外观检查、断口宏微观形貌观察及金相分析,对其中一件典型管件进行了综合分析。结果表明:管件断裂于引接管长管弯管段球座根部位置,断裂起源于表面的钎料层,断口可见明显的疲劳条带特征,断裂性质为疲劳断裂。失效的主要原因是由于钎料层不均匀,韧性较差,且管件在装配过程中存在较大的变形,使钎料层沿枝晶开裂,形成原始裂纹。在防喘压力信号管工作过程中,在振动应力作用下发生疲劳扩展并最终导致管件断裂。通过严格控制钎焊过程并防止装配中管件发生较大的变形可以避免该类故障。

Antisurge pressure signal pipes in engines fractured at the soldering zone time after time. The failure cause of a fractured pipe was analyzed. The results show that the fracture mode of the pipe is fatigue fracture. The fracture initiated from the surface solder layer. Fatigue strips could be easily found at the fracture surface. Because of the inhomogeneity and lower ductility of the solder layer and the serious deformation caused during assembly, the solder layer cracked along the pine-tree crystal boundary and initial cracks came into being. Fatigue cracks propagated under the effect of vibration stress during service, and finally, the pipe fractured. Proper welding processand prevention of serious deformation can help to avoid the failure.