Al-Mg/Ti-Mg脱氧钢中夹杂物诱发点蚀行为研究

Inclusion-induced pitting corrosion behaviors in Al-Mg/Ti-Mg deoxidized steel

以不同脱氧方式熔炼的海洋工程用钢为研究对象,利用SEM、EDS及Image-Pro Plus 6.0软件对钢中夹杂物形貌、组成及尺寸分布等进行表征,通过3.5%NaCl溶液中阳极极化及腐蚀实验对钢中夹杂物诱发点蚀的行为进行探究。结果表明,与Al-Mg脱氧钢相比,Ti-Mg脱氧钢中形成了含有TiO_x的复合氧化物,夹杂数量更多且平均尺寸更小(小于1μm),有利于MnS的异质形核析出及弥散分布;低腐蚀活性的含TiOx复合氧化物及高度分散、异质局部析出MnS夹杂具有较低的点蚀敏感性及自腐蚀催化作用,降低了点蚀的诱发及扩展,有效提高了钢的抗点蚀性能。

With marine engineering steels smelt by different deoxidation operations as the research objects,the morphology,composition and size distribution of inclusions in steel samples were characterized by SEM,EDS and Image-Pro Plus 6.0software.Through anodic polarization test and immersion test in 3.5% NaCl solution,the pitting corrosion behaviors initiated by inclusions in steels were investigated.The results show that compared with Al-Mg deoxidized steel,TiOx-containing composite oxides are formed in Ti-Mg deoxidized steel,together with larger inclusion amount and smaller particle size（less than 1μm）,which is beneficial to the hetergeneous nucleation of MnS and its dispersive distribution.Moreover,the pitting susceptibility as well as self-corrosion effect of TiOx-containing composite oxides and MnS are relatively low,which is unfavorable for the initiation and expansion of pitting,but the pitting corrosion resistance of steel is therefore improved.