304、316L不锈钢耐氯离子和硫离子性能比较

Comparison of anti-corrosion behavior to chloride ions and sulfide ions between 304 and 316L stainless steel

利用阳极极化曲线测定了模拟冷却水体系中氯离子和硫离子对304不锈钢和316L不锈钢耐蚀性能的影响,结果显示:在实验条件下,304不锈钢受氯离子作用而点蚀的浓度界限约为150 mg/L,316L不锈钢约为250 mg/L;在相同水体中,316L不锈钢的点蚀电位明显高于304不锈钢;以[C l-]/[SO42-](mg/L)比值作比较,对304不锈钢,当[C l-]/[SO42-](mg/L)≤0.42时,氯离子不促进不锈钢的点蚀;而对316L不锈钢,[C l-]/[SO42-](mg/L)≤0.56时不引起点蚀。硫离子对不锈钢耐蚀性能的影响主要是使不锈钢的钝态电流密度Ip增大,6 mg/L硫离子可使304不锈钢的Ip值增大1.1倍,使316L不锈钢的Ip值增大0.5倍,硫离子更易使304不锈钢的耐蚀性能受到影响。

The influence of chloride ions and sulfide ions on 304 and 316L stainless steel （SS） respectively in the simulated cooling water system is studied by using anodic polarization curves. The results show that under the experiment condition, the minimum chloride ion concentration at which pitting corrosion appears is about 150 mg/L for 304 SS, and about 250 mg/L for 316L SS. The pitting potential of 316L SS is obviously higher than that of 304 SS in the same water system. For 304 SS, the chloride ions will not accelerate the pitting on the SS when [Cl^-]/[SO4^2-] （mg/L） ≤0.42, and the pitting will not appear for 316L SS when [Cl^-]/[SO4^2-] （mg/L） ≤0.56. The main influence of sulfide ions on the SS is that they increase the passive current density Ip. The Ip value increases 2.1 times for 304 SS and 1.5 times for 316L SS respectively with 6 mg/L sulfide ions. The sulfide ions exert a greater influence on 304 SS than on 316 L SS.