35CrMoA抽油杆扳手方失效研究

Failure Analysis on 35CrMoA Sucker Rod Wrench

通过宏观观察、理化性能检测、显微组织和断口形貌分析,对35CrMoA抽油杆扳手方失效原因进行了分析。结果表明:抽油杆扳手方的失效形式为典型的腐蚀疲劳断裂,疲劳源位于抽油杆表面腐蚀坑处。腐蚀产物中除含有大量Fe的氧化物外,还有较多的硫化物和各种盐类物质;抽油杆扳手方的显微组织主要为回火索氏体+铁素体。腐蚀坑易于产生疲劳裂纹,裂纹沿硫化物及带状组织扩展,最终导致腐蚀疲劳失效。最后,提出了减少同类抽油杆断裂失效发生的措施。

The failure reasons for 35CrMoA sucker rod wrench were analyzed by macroscopic observation, physical and chemical properties detection, microstructure and failure morphology analysis. The results show that the failure mode of 35CrMoA sucker rod wrench is typical corrosion fatigue fracture. The crack source is located at the surface corrosion pits of sucker rod wrench. There are large amounts of Fe oxides in corrosion products, and other more sulphur and various salts materials. The microstructure of sucker rod wrench is tempered sorbite＋ferrite. The corrosion pits are easy to generate fatigue cracks. The cracks propagate along the sulfides and banded structure, which can eventually lead to the corrosion fatigue failure. Finally, some measures are put forward to decrease the occurrence of similar rod fracture failure.