抗大应变管线钢X80在碱性腐蚀环境中的耐蚀性

Corrosion resistance of X80 high deformability pipeline steel in simulated alkaline solution

利用极化曲线、交流阻抗谱、Mott-Schottky曲线分析、循环极化曲线的方法,研究了X80抗大变形（X80HD）管线钢在模拟土壤碱性腐蚀环境（0.5 mol/L Na2CO3＋1 mol/L Na HCO3溶液）中的耐蚀性。结果表明,该钢在25~95℃范围内均会发生钝化现象,氧气不是钝化发生的必要条件;随着温度升高,钝化变得不稳定,自腐蚀电位减小,自腐蚀电流密度增加,电荷转移电阻减小,耐蚀性变差;25℃时,加入0.5%Na Cl未见明显点蚀,而加入1.5%Na Cl后发生了严重的点蚀,表面可见大量腐蚀坑的存在;一定程度上升高温度可以降低X80HD管线钢在添加Cl-的溶液中发生点蚀的可能性,这主要是由于升高温度,OH-浓度增加所致。

The corrosion resistance of X80 high deformability pipeline steel in simulated alkaline solution（ 0. 5 mol / L Na2CO3-1 mol / L Na HCO3） was studied by polarization curves,electrochemical impedance spectroscopy,and Mott-Schottky analysis. The results show that passivity can be established from 25 ℃ to 95 ℃ and O2 is not the requirement for passivity. The passivity shifts towards to be weaker with the temperature increasing. The corrosion potential decreases and corrosion current density increases with the temperature increasing,indicating the corrosion resistance becomes weaker. At 25 ℃,serious pitting happened when adding 1. 5% Na Cl and a lot of pitting holes can be seen on the steel surface,but not with 0. 5% Na Cl. Increasing the temperature partly is good for suppressing the occurrence of pitting because of the higher OH-concentration in solution.