高镜面P80模具钢相变行为及硬度研究

Study on the phase transformation behavior and the hardness of XFP80 die steel

利用Gleeble 3800热模拟机研究了高镜面P80模具钢相变规律,采用热膨胀法及金相法建立了CCT曲线,分析了工艺参数对组织及硬度的影响.结果表明:随着冷却速度的减慢,过冷奥氏相转变开始温度逐渐提高,由405℃提高到560℃.当冷却速度在2～15℃/s区间时,随冷却速度的增加,试验钢贝氏体含量逐渐减少;当冷却速度大于15℃/s时,试验钢显微组织主要为板条马氏体.在整个试验条件下,试验钢显微硬度随着冷速降低而逐渐下降,硬度均值由366 HV10降低到287 HV10.

The phase transformation behavior of XFP80 die steel was studied through Gleeble 3800 thermo-mechanical simulator. The continuous cooling transformation(CCT) curve was established by using thermodilatometry and metallographic method, and the effect of process parameters on microstructure and hardness was analyzed. The experimental results show that with slowing down of the cooling rate, the starting temperature of phase transformation of under-cooled austenite increases gradually from 405 ℃ to560 ℃.The bainite content in the tested steel decreases gradually as the cooling rate accelerates in the period of 2 ℃/s ~15 ℃/s;When the cooling rate is greater than 15 ℃/s, the microstructure of the tested steel is mainly lath martensite. The micro-hardness of the tested steel decreases with the decelerating of cooling rate(during 10 ℃/s ~500 ℃/h), and the average value of the hardness reduces from 366 HV10 to287 HV10.