7075-T73铝合金高锁螺母在装配时发生纵向断裂。通过宏观观察、扫描电镜分析、能谱分析以及金相检验等方法，结合生产工艺和零件复查结果，对高锁螺母的断裂原因进行了分析。结果表明：原材料中存在氧化铝夹杂，在装配应力作用下裂纹起源于氧化铝夹杂处，并沿厚度方向扩展，最终导致高锁螺母断裂。建议增加原材料缺陷检查工序以及严格执行无损检测工艺，避免此类故障再次发生。

Longitudinal fracture occurred in high lock nut of 7075-T73 aluminum alloy during assembly. The causes of fracture on high lock nut were analyzed by means of macro observation, SEM analysis, energy spectrum analysis and metallographic examination, combined with production process and parts review results. The results show that there was alumina inclusion defect in the raw material, the cracks started at the alumina inclusion and expanded along the thickness direction under the assembly stress, which resulted in the fracture of high lock nut. Adding raw material defect inspection process and implementing NDT process strictly were recommended to avoid the recurrence of such failure.