离子渗氮对X80钢在库尔勒土壤溶液中电化学腐蚀行为的影响

Effect of plasma nitriding on electrochemical corrosion behavior of X80 pipeline steel in Kuerle soil simulated solution

关键词:  离子渗氮  X80管线钢  电化学腐蚀  土壤模拟溶液  库尔勒 

Key words:  plasma nitriding  X80 pipeline steel  electrochemical corrosion  soil simulated solution  Kuerle

摘要:

通过对X80钢进行离子渗氮处理,研究其在库尔勒土壤模拟溶液中浸泡30天的耐腐蚀性能。通过动电位极化曲线和阻抗谱测试X80钢渗氮层对腐蚀性能的影响。结果 表明,经离子渗氮的试样比X80钢更耐蚀,其自腐蚀电位为-393 mV,比X80钢高出337 mV,自腐蚀电流密度为0.046 A/cm²,约是X80钢的1/1 000。离子渗氮处理使X80钢表面生成了ε相和γ′相,可显著提高自腐蚀电位,使腐蚀反应更难发生。同时,显著降低了自腐蚀电流密度。采用SEM、XRD和EDS技术对腐蚀产物膜的表面形貌和组成成分进行测试分析表明,腐蚀产物主要是Fe₃O₄和β-FeOOH。

Abstract:

This paper studied the corrosion resistance of X80 steel in Kuerle soil simulated solution for 30 days after the surface of X80 steel was treated by plasma nitriding. The influence of plasma nitriding layer of X80 steel on corrosion property was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the corrosion resistant of plasma nitriding treated specimen are more stronger than the raw X80 steel, with a corrosion potential of about -393 mV and a corrosion current density of about 0.046 μA·cm-2, which are about 337 mV higher than X80, and only about 1/1 000 of the corrosion current density of X80 steel. Compared with the X80 steel, the ε phase and γ′ phase by nitrides increased the corrosion potential significantly, which caused the happen of corrosion reaction more difficultly, and reduced the corrosion current density greatly. The surface morphology and composition of corrosion products were investigated by SEM, XRD and EDS. The result indicated that the corrosion products were mainly composed of β-FeOOH and Fe₃O₄.