Abstract: The continuous cooling expansion curve of 18CrNiMo7-6 wind power steel was tested by using a Gleeble-3800 thermal simulator at a cooling rate of 0. 1-30 ℃/s. The static continuous cooling transformation curve （CCT curve） of 18CrNiMo7-6 wind power steel was plotted by using metallographic hardness method. The microstructure transformation law of 18CrNiMo7-6 wind power steel under different cooling rate conditions was analyzed. The experimental results show that the Ac₁ phase transition temperature of 18CrNiMo7-6 wind power steel is 765 ℃， and the Ac₃ phase transition tempera ture is 843 ℃. When the cooling rate is less than 0. 5 ℃/s， the microstructure of the experimental steel is ferrite and pearlite， and high-temperature phase transformation occurs； At a cooling rate of 0. 5-1 ℃/s， ferrite disappears and plate-like martensite is initially formed； Starting from 2 ℃/s， the microstructure is mainly bainite and martensite， with both medium temperature and low temperature phase transformations occurring simultaneously； After 10 ℃/s， the bainite content de creases and the martensite content increases with the increase of cooling rate； When the cooling rate is greater than 20 ℃/s， the microstructure is entirely martensitic with only low-temperature phase transformation occurring； During the process of increasing the cooling rate from 0. 1 ℃/s to 30 ℃/s， the hardness of the wind power steel shows an upward trend.

Key words: 18CrNiMo7-6, Continuous Cooling Transformation Curve, Microstructure, Hardness

摘要： 利用 Gleeble-3800 热模拟机对 0. 1~30 ℃/s 冷却速度下 18CrNiMo7-6 风电钢连续冷却膨胀曲线进行测试。 结合金相-硬度法绘制了 18CrNiMo7-6 风电钢静态连续冷却转变曲线（CCT 曲线），分析了不同冷却速率条件下 18CrNiMo7-6风电钢组织转变规律。实验结果表明，18CrNiMo7-6风电钢奥氏体相变点 Ac₁相变温度为 765 ℃，Ac₃ 相变温度843 ℃。当冷却速度小于0. 5 ℃/s时，试验钢组织为铁素体和珠光体，发生高温相变；冷却速度0. 5 ~ 1 ℃/s 时，试验钢中铁素体逐渐减少，开始出现板条状马氏体组织；冷速大于 2 ℃/s时，试验钢组织主要为贝氏体及马氏 体，同时发生中温相变和低温相变；随冷速增加钢中贝氏体组织含量减少，马氏体组织含量增多；冷速大于20 ℃/s， 组织全部为马氏体，只发生低温相变；冷速由0. 1 ℃/s增加至30 ℃/s过程中，风电钢试样硬度逐渐增加。

关键词: 18CrNiMo7-6, 连续冷却转变曲线, 组织, 硬度