HFW焊管在NS4及鹰潭土壤模拟溶液中的腐蚀及机理分析

摘要

利用浸泡试验、电化学阻抗谱（EIS）和X射线衍射（XRD）对HFW焊管在NS4和鹰潭土壤（YT）模拟溶液中的腐蚀过程及机理进行了研究。结果表明： HFW焊缝及母材在2种溶液中的腐蚀主要受阴极扩散过程控制；在16天的浸泡试验中，试样在鹰潭土壤模拟溶液中的热力学稳定性高于NS4溶液，同一溶液中焊缝试样的热力学稳定性高于母材；在2种溶液中试样表面腐蚀产物电阻R1的数值要远小于电荷转移电阻Rt，试样在鹰潭土壤模拟溶液中的Rt较小，电极过程更容易进行，同种溶液中，焊缝试样的Rt要大于母材；在2种溶液中， HFW焊管的主要腐蚀产物为FeOOH（针铁矿）和Fe2O3（赤铁矿）。%The corrosion process and mechanism of HFW pipe in NS4 solution and Yingtan soil simulated solution were studied by the means of immersion test, electrochemical impedance spectroscopy(EIS) and X-ray diffraction(XRD). The result indicated that the corrosion of HFW pipe weld and base metal was controlled by cathode diffusion process in above two solutions. During the 16 days immersion test, the thermodynamic stability of the pipe in Yingtan soil simulated solution was higher than that in NS4 solution, for the same solution, the weld was more stable than base metal. In two simulated solutions, the corrosion productions resistance R1 were less than the charge transfer resistance Rt, the Rt of the pipe in Yingtan soil simulated solution was smaller than that in NS4 solution. For same solution, the Rt of the weld was higher than that of base metal. The primary corrosion products of HFW pipe in these two solutions were FeOOH(goethite) and Fe2O3(hematite).