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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Fe_3O_4,γFeOOH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γFeOOH和αFeOOH的晶粒长大.
Three kinds of bridge steel with 3.5% Ni content were selected. The corrosion resistance of bridge steel under simulated atmospheric environment was simulated by wet-dry immersion accelerated corrosion test. The contents of Mn and Cu were analyzed by metallographic microscope, XRD and SEM. The results showed that the microstructure of bridge weathering steel was composed of quasi-polygonal ferrite, acicular ferrite and granular bainite. With the increase of Mn content And the corrosion resistance of steel increases.Ni and Mn are uniformly distributed in the rust layer and Cu is enriched in the defects such as cracks or vugs in the rust layer.The rust layer mainly consists of Fe 3 O 4, γFeOOH and α-FeOOH and corrodes at different times The corrosion resistance of γ-FeOOH and α-FeOOH are closely related to the corrosion rate of steel. Increasing the Mn content can promote the formation of γ-FeOOH and α-FeOOH, and suppress the grain growth of γFeOOH and αFeOOH Big.