X80管线钢埋弧焊焊接接头的组织和腐蚀性能

Microstructures and corrosion properties of submerged arc welded joint for X80 pipeline steel

采用H08MnMoA焊丝埋弧焊焊接X80管线钢.利用扫描电镜分析焊接接头微观组织;采用动电位极化和电化学阻抗法研究了X80管线钢其焊接接头在0.5 mol/LNaHCO3+0.02 mol/L NaCl溶液中的腐蚀行为.结果表明,在0.5 mol/L NaHCO3+0.02mol/L NaCl溶液中,由于显微组织上的差异,X80钢母材的耐点蚀性能最好;焊缝在短时间内的耐点蚀性能基本与母材处于同一水平,但长时间浸泡后的耐点蚀性能却比母材要差;热影响区的耐点蚀性能最差,且相对于母材和焊缝的差值较大.

The X80 pipeline steel was welded using the submerged-arc welding procedure.The microstructure of the welded joint was observed by scanning electron microscope（SEM）,the corrosion behavior of the welded joint of X80 pipeline steel was investigated by method of potentiodynamic polarization and electrochemical impedance spectroscopy（EIS）.The results show that the welded joint has good pitting corrosion resistance generally.However in solution of 0.5 mol/L NaHCO3＋0.02 mol/L NaCl,the base metal of X80 pipeline steel showed the best resistance to pitting corrosion because of the differences in microstructure.Though it can keep the same level as the base metal at first,the pitting corrosion resistance of weld metal will get worse after longtime immersion.The pitting corrosion resistance of heat-affected zone was always the worst and had a large gap with the base metal and weld metal.