氯离子对316L不锈钢临界点蚀温度的影响

Influence of Chloride ion on Critical Pitting Temperature of 316L Stainless Steel

在外加恒电位下,通过测腐蚀电流密度-温度曲线的方法研究了Cl^-含量对316L不锈钢临界点蚀温度(CPT)的影响。结果表明:在临界点蚀温度以下,试样表面钝化膜比较稳定,超过该温度后,试样表面开始发生点蚀。Cl^-含量越高,316L不锈钢临界点蚀温度越低,且表面的点蚀坑越多。现场的腐蚀产物分析表明,腐蚀产物表面稀疏,主要元素为O、Fe、C、Cl。现场生产水Cl^-质量浓度高达21.431g/L,对316L不锈钢的腐蚀极其严重。

The influence of Cl- on critical pitting temperature （CPT） of 316L stainless steel was studied by monitoring the evolution process of corrosion current density with temperature at a constant applied potential. The passive film could form on the surface of the sample when temperature was below the CPT. The pitting corrosion occurred on the surface of the sample when temperature was above the CPT. As the Cl- concentration rose, the critical pitting temperature of the stainless steel declined, and the number of pits on it increased. The analysis of corrosion products from the field showed that the surface of corrosion products was sparse, and the main elements were oxygen, iron, carbon and chlorine. The concentration of Cl- in water was as high as 21. 431 g/L, and the corrosion of 316L stainless was extremely serious.