钻杆管体横向开裂失效原因分析与预防

Drill Rod Lateral Fracturing Failure Causation and Prevention

针对一起钻杆管体横向开裂的案例,通过对发生横向开裂的失效钻杆进行断口形貌的宏观及微观观察、金相分析、物相分析,以及对钻杆尺寸、化学成分及力学性能的综合分析,并结合钻杆的受力状态,指出钻杆的失效原因是钻井液中的氧气对钻杆的内外表面产生严重腐蚀,同时钻杆在承受拉压弯扭等复杂交变载荷的作用下,腐蚀坑底部产生率先产生疲劳裂纹,随着外壁裂纹的不断扩展,导致钻杆横向开裂,并针对这种失效形式,提出了预防措施及建议。

In allusion to a drill rod lateral fracturing case,carried out a laterally fractured drill rod fracture surface morphological macroscopic and microscopic observations,metallographic analysis,phase analysis,as well as integrated analysis of rod size,chemical composition and mechanical property.Combined with rod stress state,pointed out the failure causation is from oxygen in drilling fluid produced severe corrosion on rod internal and external surfaces.Meanwhile,under the pulling,compressing,bending and torsion forces alternating loads,the corrosion pit bottom initiatively produced fatigue cracking,with the external wall fracture ever expanding caused rod lateral fractured.In allusion to this failure mode put forward prevention measures and proposals.