焊接于LF2铝合金燃油系统导管上的传感器管接头，使用一段时间后在焊缝焊趾处出现裂纹。采用宏观观察、断口宏观、金相检验、焊接质量检查及焊接结构改进验证试验等方法对开裂原因进行了分析。结果表明：该LF2铝合金燃油导管接头的开裂性质为疲劳开裂。裂纹起源于导管外表面应力集中处，燃油管管接头焊缝焊趾处应力水平较高，且受到与导管轴向垂直方向的振动应力的叠加，最终导致焊缝开裂。

A crack was found on the weld toe of sensor pipe joint by welding on the LF2 aluminum alloy fuel system pipe after being used for a period of time. The causes of cracking were analyzed by means of macro observation, fracture macro, metallographic examination, welding quality inspection and verification test of welding structure improvement. The results show that the cracking property of the LF2 aluminum alloy fuel pipe joint was fatigue cracking. The crack originated from the stress concentration on the outer surface of the pipe. The stress level at the weld toe of the fuel pipe joint was high, and was superimposed by the vibration stress perpendicular to the axial direction of the pipe, resulted in the weld cracking.