利用开路电位测量、电化学阻抗谱测量和扫描电镜（SEM）观测研究了在含饱和CO₂的3.5% NaCl水溶液中不同介质条件对X65管线钢及其焊接接头不同区域CO₂腐蚀的影响。结果表明：在pH较低环境中，X65管线钢表面难以形成致密的FeCO₃腐蚀产物膜，而在pH较高环境中，即便温度较低也能生成致密的腐蚀产物膜，且温度越高，腐蚀产物膜越致密，X65管线钢的腐蚀速率下降，点蚀加剧；X65管线钢焊接接头不同区域中，母材最先形成致密的腐蚀产物膜，其次是热影响区，最后是焊缝区，但焊缝区形成的腐蚀产物膜较其他两个区域形成的更加致密。

The effects of medium condition on CO₂ corrosion of X65 pipeline steel and different zones of its welded joint were studied in 3.5% NaCl solution with saturated CO₂ by open-circuit potential measurement, electrochemical impedance spectroscopy testing and scanning electron microscopy (SEM) observation. The results show that a dense corrosion product film of FeCO₃ was difficult to form on the surface of X65 pipeline steel in low pH environment. But it could form in high pH environment even at a low temperature, the higher the temperature, the denser the corrosion product film. And with the increase of temperature the average corrosion rate of X65 pipeline steel decreased and the pitting corrosion resistance became worse. In the different zones of X65 pipeline steel welded joint, the base metal formed a dense corrosion product film first, followed by the heat affected zone, and finally the weld zone. The product film formed on the weld zone was denser than that formed on the base metal and heat affected zone.