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采用Gleeble 1500热模拟试验机,模拟在1100℃变形30%和在850℃变形35%变形之后在0.5～50℃/s冷却速率下的X120管线钢的连续冷却过程,通过光学显微镜、透射电镜、维氏硬度计及显微力学探针分析,研究了X120管线钢的相变温度、显微组织及维氏硬度的变化规律。结果表明:当冷却速率在20～50℃/s时,试验钢的组织主要为下贝氏体和板条马氏体。下贝氏体的相变开始温度在470℃左右,终止温度在320～330℃。钢的硬度随冷却速率提高而逐渐增加,最高硬度达320 HV。
The Gleeble 1500 thermal simulation test machine was used to simulate the continuous cooling process of X120 pipeline steel at 30% deformation at 1100 ℃ and 35% deformation at 850 ℃. The cooling rate of X120 steel was simulated by optical microscope, transmission electron microscope, Vickers hardness tester and micro-mechanical probe analysis of X120 pipeline steel phase transition temperature, microstructure and Vickers hardness changes. The results show that the microstructure of the test steel is mainly bainite and lath martensite when the cooling rate is 20 ~ 50 ℃ / s. Lower bainite transformation start temperature of about 470 ℃, termination temperature of 320 ~ 330 ℃. The hardness of steel gradually increases with the cooling rate, the maximum hardness of 320 HV.