Abstract: In order to understand phase transformation of Cu-containing bridge weathering steels, continuous cooling transformation (CCT) diagrams of bridge weathering steels with different Cu contents were studied by using optical microscope and microhardness measurement. The results showed that Cu could reduce bainite transformation temperature, but had little effect on initial transformation temperature. The increase of Cu content refined ferrite and bainite grain size, and enhanced the microhardness of ferrite, but the microhardness of bainite was reduced by about 20 Hv. With the increase of cooling rate, ferrite grain size was changed from 10 to 6 mm, and volume fraction from 58% to 17%. The microhardness of ferrite had little change, kept at about 240 Hv. The microhardness of bainite was increased from 250 to 300 Hv.

Key words: bridge weathering steel, phase transformation, microhardness

摘要： 为了探索含Cu桥梁耐候钢连续冷却过程中的相变规律，利用金相和显微硬度的方法分析了不同Cu含量桥梁耐候钢的CCT曲线. 结果表明，Cu可以降低贝氏体转变温度，而对铁素体开始转变温度影响不大. 增加Cu含量可以细化铁素体和贝氏体晶粒，增加铁素体的显微硬度，贝氏体的显微硬度降低约20 Hv. 随冷却速度增加，实验钢的铁素体晶粒尺寸由10 mm降到6 mm，体积百分数由58%降到17%；铁素体显微硬度保持在240 Hv左右，变化不大；贝氏体显微硬度由250 Hv增加到300 Hv.

关键词: 桥梁耐候钢, 相变规律, 显微硬度