中文摘要：

采用腐蚀质量损失、扫描电子显微镜、X射线衍射仪、线性极化等测试手段,研究无光照、半光照及全光照三种实验条件对Q450NQR1耐候钢在干湿交替条件下腐蚀行为的影响规律.结果表明：光照对实验钢干湿交替腐蚀过程影响显著.实验钢在腐蚀前期（48 h）腐蚀速率大小依次为半光照、无光照和全光照,腐蚀中后期（72~96 h）腐蚀速率由大到小依次为半光照、全光照和无光照.腐蚀宏观形貌有明显差别,无光照时试样腐蚀产物呈淤泥状分布整个表面,有光照条件时腐蚀产物则呈颗粒状分布,但全光照条件时腐蚀产物颗粒更细且孔隙更小.另外,三种条件下腐蚀产物物相组成一致,但含量有所不同.线性极化测试得出96 h极化电阻由大到小依次为无光照、全光照和半光照,这一结果与通过腐蚀失重得出的腐蚀速率结果一致.

英文摘要：

The effects of no light, half-day light and all-day light on the corrosion behavior of Q450NQR1 weathering steel in the wet-dry cycle condition were examined by corrosion mass loss, scanning electron microscopy, X-ray diffraction and linear polarization tests. The results indicate that light significantly affects the corrosion process in the wet-dry cycles. In the early stage of steel corrosion （before 48h）, the corrosion rate from fast to slow is followed by half-day light, no light, and all-day light; but in the later period （72- 96 h）, the corrosion rate is ordered by half-day light, all-day light, and no light. The corrosion morphologies are obviously different. The corrosion products are silt-shape distribution in no light condition and particulate distribution in light condition, while they are particle-distributed with finer particles and smaller pores in all-day light condition. X-ray diffraction results show that the corrosion products are the same, but the contents are different in the three conditions. By linear polarization tests, the polarization resistance is obtained in the order from fast to slow of no light, half-day light, and all-day light at 96 h, which is well consistent with the order of corrosion mass loss rate.