某油田钻井队在空气钻井过程中发生一起钻铤断裂失效事故。采用宏观观察、化学成分分析、力学性能试验、硬度测试、金相检验、微观观察等方法对钻铤断裂失效的原因进行了分析。结果表明：钻铤螺纹接头与钻铤尺寸不匹配，内螺纹接头处为薄弱环节，在空气钻井过程中发生了疲劳断裂。建议采用与钻铤尺寸匹配的螺纹接头，并在钻铤接头部位增加应力分散槽，或者使用双台肩接头钻铤。

A drilling team in an oil field had a drill collar fracture failure accident during air drilling process. The causes of fracture failure of the drill collar were analyzed by means of macro observation, chemical composition analysis, mechanical property test, hardness test, metallographic examination, micro observation and so on. The results show that the thread joint of the drill collar did not match the size of the drill collar. The internal thread joint was a weak link and fatigue fracture occurred during air drilling process. It is suggested to adopt thread joint matching the size of the drill collar and to add stress dispersion grooves at the joint of the drill collar, or to use double shoulder joint drill collar.