稀土元素对低合金钢耐腐蚀性能影响的研究现状

Effect of rare earth elements on the corrosion resistance of low alloy steels

近年来稀土在钢中的应用越来越受到重视。文中在稀土钢研究成果的基础上,分析了稀土元素对低合金钢耐腐蚀性的作用机理:稀土通过置换氧化铝和MnS等夹杂物,使其变质形成稀土夹杂物,尺寸为2~5μm。通过添加适量稀土元素(w(RE)/w(S)=1.4~4.0),含稀土的低合金钢中近87%的夹杂物尺寸小于2.5μm,可降低钢基体的点蚀源和敏感性。同时,稀土促进低合金钢锈层中合金元素富集并产生大量致密的α-FeOOH,从而降低腐蚀速率。稀土元素的加入,腐蚀电位正移,阻碍电荷传输,降低了自腐蚀电流密度及电化学腐蚀速率,提高了稀土微合金钢的耐腐蚀性能。

In recent years,the application of rare earth elements in steel has been increasingly highlighted.Based on the related research results for rare earth steel,the corrosion resistance mechanism of rare earth elements on low alloy steel is analyzed and summarized.The inclusions in steel convert to rare earth inclusions with sizes of 2-5 μm by substitution of rare earth elements,such as alumina and manganese sulfide inclusions.By adding an appropriate amount of rare earth elements(w(RE)/w(S)=1.4-4.0),nearly 87% of the inclusions in low alloy steel containing rare earth are less than 2.5 μm,which reduces the pitting source and sensitivity of the steel matrix.At the same time,rare earth can promote the enrichment of alloy elements in the rust layer of low alloy and generate a large amount of dense α-FeOOH,thereby reducing the corrosion rate.With the addition of rare earth elements,the corrosion potential shifted positively,which hindered the charge transfer,reduced the selfcorrosion current density and electrochemical corrosion rate,and thus greatly improved the corrosion resistance of rare earth micro-alloyed steel.