采用热膨胀仪测定20Cr1Mo1VTiB钢在不同淬火温度（950~1 100 ℃）下的贝氏体转变点和较佳淬火温度下的连续冷却相变点，结合组织观察和硬度测试绘制连续冷却转变曲线；利用经验公式建立相变点和相转变量与冷却速率的关系，并计算相变激活能。结果表明：随着淬火温度升高，试验钢中贝氏体转变温度降低，较佳淬火温度为1 050 ℃；冷却速率不高于0.5 ℃·s^-1时，过冷奥氏体转变产物为先共析铁素体、珠光体和贝氏体，冷却速率超过0.5 ℃·s^-1时则为单一贝氏体；相变点-冷却速率和相转变量-冷却速率拟合曲线与试验结果吻合较好，先共析铁素体和贝氏体相变激活能分别为744.8，274.9 kJ·mol^-1。

The bainite transformation point at different quenching temperatures (950-1 100 ℃) and the continuous cooling phase transformation point at the optimal quenching temperature of 20Cr1Mo1VTiB steel were measured on a thermal dilatometer. Then the continuous cooling transformation curves were drawn by combination of the phase transformation points, microstructure observation and hardness test. The relationship between the phase transformation point or transformation amount and the cooling rate was established with empirical equations, and the phase transition activation energy was calculated. The results show that the bainite transformation temperature of the test steel decreased with increasing quenching temperature; the preferred quenching temperature was 1 050 ℃. The supercooled austenite transformation products were proeutectoid ferrite, pearlite and bainite with cooling rates not higher than 0.5 ℃·s^-1, and were single bainite with cooling rates higher than 0.5 ℃·s^-1. The fitting curves of phase transformation point- and phase transformation amount-cooling rate were in good agreement with the test results. The activation energy of proeutectoid ferrite and bainite transition was 744.8, 274.9 kJ·mol^-1, respectively.