选择3种Ni含量为3.5%的桥梁钢, 采用干湿周浸加速腐蚀实验模拟海洋大气环境下桥梁钢的耐腐蚀性能变化, 并利用金相显微镜、 XRD和SEM等分析了不同Mn和Cu含量桥梁耐候钢组织以及其腐蚀不同时间的腐蚀形貌和锈层特征. 结果表明: 桥梁耐候钢的组织由准多边形铁素体、针状铁素体和粒状贝氏体组成; 随着Mn含量的增加, 钢的耐蚀性能增加; Ni和Mn在锈层中均匀分布, Cu在锈层的缝隙或孔洞等缺陷处富集. 锈层主要由Fe₃O₄, γ-FeOOH和α-FeOOH组成, 腐蚀不同时间后的试样锈层组成相有所不同; γ-FeOOH和α-FeOOH与钢的腐蚀速率密切相关; 增加Mn含量可以促进 γ-FeOOH和α-FeOOH的生成, 同时抑制γ-FeOOH和α-FeOOH的晶粒长大.

In order to understand the corrosion behavior of bridge weathering steels at marine atmosphere, three type steels containing 3.5% Ni were prepared for alternate wet-dry accelerated corrosion test. Microstructures, rust layer morphologies and characteristics of bridge weathering steels with different Mn and Cu contents at different stages were studied by using optical microscope, XRD and SEM. The results show microstructures of the bridge weathering steels are composed of quasi-polygonal ferrite, acicular ferrite and granular bainite. Corrosion resistance of the steels is improved with Mn content increasing. Distributions of Ni and Mn are uniform inside rust layers, but Cu is enriched at gaps and pores in rust layers. Crystal phases are mainly composed of Fe₃O₄, γ-FeOOH and α-FeOOH in rust layers, however, the compositions are somewhat different at different stages. The formation of γ-FeOOH and α-FeOOH is closely related to the change in corrosion rate. With increasing Mn content, the formation of γ-FeOOH and α-FeOOH are accelerated and their sizes are restrained.