锈层对船体钢耐腐蚀性能影响研究

Effect of Rust Layer on Corrosion Resistance of Hull Steel

选择5种不同类型的船体钢,在3%(质量分数)NaCl溶液中浸泡1 a,用金相显微镜观察内、外锈层形貌特征和腐蚀形貌,分析锈层下钢的腐蚀特征;记录自腐蚀电位(OCP)的变化,评价锈层对腐蚀倾向性的影响;利用电子探针(EMPA)分析锈层的形貌和内锈层元素分布;通过计算质量损失得到钢的平均腐蚀速率。结果表明,外锈层对钢腐蚀的影响较小;内锈层的缺陷与钢腐蚀形貌中的腐蚀坑对应;当钢中的Ni和Cr元素含量较高时,由于Cr元素在其内锈层和基体交界面富集,其平均腐蚀速率最小。

Five different types of hull steel were immersed in 3%NaCl solution for one year; the morphologies of inner and outer rust layers and the corrosion morphologies were obtained by metallographic microscope; and the corrosion characteristics of steel under rust layer were analyzed. The change in corrosion potential （OCP） were recorded for evaluation of influence of rust layer on corrosion tendency; the rust layer morphology and element distribution in inner layers were analyzed by means of electron probe micro-analyzer （EMPA）. Average corrosion rate of steels was got by weight loss calculation. The results showed that outer rust layers have little influence on steels corrosion; the corrosion pits seen from steels corrosion morphology corresponds to defects in the inner rust layers; minimum of average corrosion rate is caused by the enrichment of Cr element in the inner rust layer and matrix cross-interface when steel has higher Ni and Cr content.