Cr对低合金钢在流动NaCl溶液中耐蚀性的影响

Influence of Cr on corrosion resistance of low alloy steels in flowing NaCl solution

对碳钢和Cr含量不同的实验钢在流速为0.8m/s的流动的3.5%(质量分数)NaCl溶液中的腐蚀行为进行研究,最长腐蚀周期为192h。对4种实验钢的腐蚀失重进行了比较,并利用动电位极化曲线、SEM、EPMA和TEM等分析手段,对实验钢表面形成锈层的特征进行了系统研究。结果表明,含Cr实验钢的腐蚀失重低于碳钢,并且随Cr的质量分数由0.5%提高至2%,腐蚀失重亦降低。Cr元素在内锈层中的富集是含Cr钢耐蚀性改善的重要原因。这种富集可使腐蚀产物颗粒获得细小的尺寸,致密内锈层形成的原因就是由于这种尺寸细小的腐蚀产物的形成,使内锈层的保护性获得明显的改善。

The corrosion behaviors of carbon steel and Cr containing steels with various Cr contents were investi- gated in NaC1 solution of 3. 5 % （mass fraction） with velocity of 0. 8 m/s, and the longest corrosion time was up to 192 h. The weight losses for four experimental steels were compared. The rust layers forming on sur- faces of four experimental steels were analyzed in detail by using the methods of potentiodynamic polarization curve, SEM, EPMA and TEM. The results show that the weight losses of Cr containing steels are lower than that of carbon steel in flowing NaC1 solution under the same corrosion time. With mass fraction of Cr in the steel increasing from 0.5 % to 2 0/60 , the weight loss is also reduced. The concentration of Cr in the inner rust layer is the main reason for corrosion resistance of Cr containing steels improved. This concentration could make the particles of corrosion products have fine size. The inner rust layer becomes more compact because of the formation of fine corrosion products, and the protectiveness of inner rust layer can be improved remarkably.