空气钻井钻杆断裂失效分析

对某空气钻井期间发生的钻杆断裂事故作了详细调研，对断裂钻杆样品断口进行了宏观分析和微观分析，对断裂钻杆材料的化学成分、力学性能和金相组织进行了全面试验分析。结合钻杆使用情况和试验分析结果，认为钻杆断裂原因是加厚过渡带消失部位存在制造缺陷，裂纹从缺陷处萌生并扩展，最终导致钻杆发生疲劳断裂。

The Analysis on the Fracture Failure of Air Drilling Pipes

A detailed survey has been carried out, which aims at the fracture failure of drilling pipes during the period of air drilling. Then the macro and micro analyses are conducted on the breakpoint of the fracture drilling pipe sample, while the overall experiment analyses focuses on the chemical components, the mechanical property and metallographic structure. According to the applied state of drilling rod and the experiment analysis, it is held that the fracture of drilling rod is caused by the manufacturing defect existing at the disappearing end of heavy transitional beh, from which the crack appears and extend, and thus results in the fatigue fracture of drilling pipes.