耐候钢适用于高海拔寒区等严酷环境地区的桥梁建设,但当前耐候钢在高海拔寒区的耐腐蚀机制不明确。为探究高海拔寒区的桥梁耐候钢的耐候机制,此处以常用的桥梁耐候钢和普通钢为研究对象,针对典型的高海拔寒区环境,开展了桥梁钢的原位腐蚀试验。结合腐蚀失重数据、锈层宏观形貌、锈层微观形貌及元素沿锈层分布规律,对耐候钢在高海拔寒区的耐蚀机制进行了分析。研究结果表明,在腐蚀周期为24月时,耐候钢的腐蚀失厚量比普通碳钢低约10%；耐候钢锈蚀产物中形成的针铁矿阻碍氧气、水分等向锈层内聚集,其是在高海拔寒区耐候的主要原因；腐蚀过程中,Cr在耐候钢内锈层内富集,导致内锈层在后续的腐蚀中会越发致密,进一步增强了耐腐蚀性能。相关研究结论可为高海拔寒区的桥梁工程建设提供理论与数据支撑。

Weathering steel is suitable for bridge construction in harsh environments, such as high-altitude cold regions. However, the corrosion resistance mechanism of weathering steel in these areas remains unclear. To investigate the weathering mechanism of bridge weathering steel in high-altitude cold regions, this study focuses on commonly used bridge weathering steel and ordinary steel. An in-situ corrosion test of bridge steel was conducted in a typical high-altitude cold environment. By analyzing corrosion weight loss data, the macroscopic appearance of the rust layer, the microscopic morphology of the rust layer, and the elemental distribution along the rust layer, the corrosion resistance mechanism of weathering steel in high-altitude cold regions was examined. The results show that after a 24-month corrosion period, the corrosion thickness loss of weathering steel is approximately 10% lower than that of ordinary carbon steel. The formation of goethite in the rust products of weathering steel hinders the penetration of oxygen, moisture, and other elements into the rust layer, which is the primary reason for its weather resistance in high-altitude cold regions. During the corrosion process, chromium (Cr) accumulates in the inner rust layer of the weathering steel, causing the inner rust layer to become denser in subsequent corrosion, further enhancing corrosion resistance. The findings of this study provide theoretical and data support for bridge engineering construction in high-altitude cold regions.

国家重点研发计划项目(2022YFB3706404)National Key Research and Development Program of China(2022YFB3706404)