Abstract: The continuous cooling transformation of 12Cr1MoV perlitic heat-resistant steel was studied by means of ther⁃ mal expansion tester， laser confocal microscope， microhardness tester and scanning electron microscope， the continuous cooling transformation （CCT） curve of experimental steel was drawn， and the effect of cooling rate on the microstructure evolution of phase transformation during cooling process was analyzed. The results show that four transition regions of fer⁃ rite， pearlite， bainite and martensite will appear in the CCT curves of 12Cr1MoV steel at the cooling rates between 0. 5 ℃/ s and 30 ℃/s. At the cooling rates between 0. 5 ℃/s and 1 ℃/s， and the transformation products are composed of ferrite and pearlite. At the cooling rates between 1. 5 ℃/s and 10 ℃/s， and the transition products are mainly composed of upper bainite and ferrite. At the cooling rates between 10 ℃/s and 20 ℃/s， and the transition products are mainly the mixed structure of upper bainite， lower bainite and martensite. At the cooling rate of 30 ℃/s， the transition product is mainly martensite. The transition structure of undercooled austenite appears upper bainite at the cooling rates between 1. 5 ℃/s and 20 ℃/s. The appearance of upper bainite in the structure leads to a decrease in the mechanical properties of the steel， which is prone to crack formation and propagation. Based on the above research results， measures to reduce the cooling rate of 12Cr1MoV steel continuous casting billets and hot rolling lines are proposed to reduce the upper bainite structure The surface cracks of the bars are effectively controlled after adjustment.

Key words: 12Cr1MoV Steel, Cooling Rate, CCT curve, Microstructure

摘要： 采用热膨胀测试仪、激光共聚焦显微镜、显微硬度仪以及扫描电镜等手段，研究了12Cr1MoV珠光体耐热钢 连续冷却相变，绘制了实验钢过冷奥氏体连续冷却转变（CCT）曲线，分析了冷却速率对冷却过程相变组织演变规律 的影响。结果表明，冷却速率为0. 5~30 ℃/s时，实验钢CCT曲线中会出现铁素体、珠光体、贝氏体以及马氏体四个 相变区域。冷却速率为0. 5~1 ℃/s时，转变产物由铁素体和珠光体组成；冷却速率为1. 5~10 ℃/s时，转变产物主要 是上贝氏体和铁素体；冷却速率为10~20 ℃/s，转变产物主要是上贝氏体、下贝氏体以及马氏体混合组织；冷却速率 为30 ℃/s，转变产物主要由马氏体组成。冷却速率为1. 5~20 ℃/s时，过冷奥氏体转变组织出现上贝氏体，会导致材 料机械性能下降，容易导致裂纹形成和扩展。基于上述研究结果，提出降低12Cr1MoV钢连铸坯和热轧线下冷速措 施，以减少上贝氏体组织，通过调整后棒材表面裂纹得到有效控制。

关键词: 12Cr1MoV钢, 冷却速率, CCT曲线, 显微组织