This study investigated the effects of Ni addition on the corrosion resistance of steel in subtropical seashore environments. Carbon steel and 3, 5, and 7% Ni steels were exposed in such an environment for a year. Addition of Ni depressed the corrosion rate of steels and number of cracks in the rust layer. Quantitative and three-dimensional measurement of the cracks with a wide range of widths and volumes in the rust layer was carried out for the exposed steel specimens using the mercury intrusion method. The total crack volume in the rust layers on 5% Ni steel was 60% lower than that for the carbon steel. It is considered that rust layers with less crack volume suppressed Cl^– migration through the rust layer. The Cl concentration near the metal interface was relatively lower in the 5% Ni steel by EPMA analysis. And the rust layer on 5% Ni steel also showed a higher permeation resistance than that formed on carbon steel. Considering the formation of rust layers with less volume crack on Ni-added steel based on Morcillo’s model, it is concluded that the Ni addition promoted the formation of a-FeOOH and suppressed the reduction of γ- and β-FeOOH, thus resulting in a more intact rust layer.

这项研究调查了亚热带海滨环境中添加镍对钢的耐蚀性的影响。碳钢和3、5和7％的Ni钢在这种环境下暴露了一年。镍的添加降低了钢的腐蚀速率和锈层中的裂纹数量。使用压汞法对裸露的钢试样进行了锈层中宽度和体积范围宽的裂纹的定量和三维测量。5％Ni钢上锈层的总裂纹体积比碳素钢低60％。认为裂纹量较小的锈层抑制了Cl ^–穿过锈层迁移。通过EPMA分析，在5％Ni钢中，金属界面附近的Cl浓度相对较低。5％Ni钢上的防锈层也显示出比碳钢上更高的耐渗透性。考虑到基于莫尔西洛模型的添加镍钢上形成的锈蚀层且体积裂纹较少，可以得出结论，添加镍促进了α-FeO​​OH的形成并抑制了γ-和β -FeOOH的还原，从而导致更完整的防锈层。