目的 针对某油田316L/L360NB机械式双金属复合管的穿孔问题，开展失效行为及原因分析，为此类管道的失效控制提供理论依据。方法 基于此失效管样的生产标准和服役工况，通过宏观检查、无损检测、化学成分分析、金相组织分析、硬度分析、扫描电镜及能谱分析等方法，结合焊接工艺规范，综合分析其穿孔失效原因。结果 该失效管样的316L衬管和L360NB基管外径、壁厚、化学成分和硬度均符合相关标准要求，金相组织未见异常。其封焊已焊穿衬管，金相组织为马氏体，未见其他焊接缺陷。点蚀均发生在封焊，腐蚀产物的主要化学元素为C、O、Fe，并含有少量的Cl。316L衬管未见腐蚀，封焊区的耐蚀性最差。结论 该双金属复合管的失效行为是局部内腐蚀穿孔，失效原因是由于不当的封焊操作致使封焊焊穿衬管，导致耐蚀性较低的封焊在高Cl?腐蚀环境中发生点蚀。封焊腐蚀穿透后，衬管与基管构成电偶腐蚀，使得耐蚀性差的碳钢基管迅速腐蚀穿孔。建议对机械式双金属复合管采用堆焊耐蚀性更好的焊材进行管端封口，以有效防止失效的再次发生。

For perforation problem of 316L/L360NB mechanically bimetallic composite pipes used in an oilfield, the work aims to provide theoretical basis for failure control of these pipes by analyzing failure behavior and cause. Based on production standards and service conditions of the faulty pipes, the cause of perforation failure was comprehensively analyzed by means of visual inspection, nondestructive testing, chemical composition analysis, metallographic structure analysis, hardness analysis, scanning electron microscope and energy spectrum analysis while referring to welding process specification. Outer diameter, wall thickness, chemical composition and hardness of 316L liner pipe and L360NB base pipe of the faulty pipe were in conformity with relevant standards, and no abnormality was detected in metallographic structure. Sealing weld has penetrated to the liner pipe, microstructure was martensite, and no other welding defects were found. Pitting corrosion occurred in the sealing weld. Main chemical elements of corrosion products were C, O and Fe, and there was a small amount of Cl as well. No corrosion was found in the 316L liner pipe, and corrosion resistance of the sealing area was the worst. Failure behavior of the bimetallic composite pipes was local internal corrosion perforation. Failure cause was that improper sealing operation caused the sealing weld to penetrate into the liner pipe, which resulted in pitting corrosion of less corrosion-resistant sealing weld in high Cl? corrosion environment. The liner and base tube constitute galvanic corrosion after the sealing penetration, which lead to rapid corrosion perforation of less corrosion-resistant carbon steel base pipe. It is suggested that ends of mechanically bimetallic composite pipes be sealed with welding materials exhibiting better corrosion resistance, so as to prevent the failure effectively.