20CrMnTi钢的等温相变行为分析及动力学建模  

Isothermal phase transformation behavior analysis and kinetic model establishment for 20CrMnTi steel

作　　者：乔靖乾 冯玮[1,2,3] Qiao Jingqian;Feng Wei(School of Materials Science and Engineering,Wuhan University of Technology,Wuhan Hubei 430070,China;Hubei Key Laboratory of Advanced Technology for Automotive Components,Wuhan Hubei 430070,China;Hubei Engineering Research Center for Green Precision Material Forming,Wuhan Hubei 430070,China)

机构地区：[1]武汉理工大学材料科学与工程学院,湖北武汉430070 [2]现代汽车零部件技术湖北省重点实验室,湖北武汉430070 [3]湖北省材料绿色精密成形工程技术研究中心,湖北武汉430070

出　　处：《金属热处理》2020年第11期115-121,共7页Heat Treatment of Metals

基　　金：国家自然科学基金面上项目(51475344);高等学校学科创新引智计划(B17034);教育部创新团队发展计划(IRT_17R83)。

摘　　要：利用Gleeble-3500热模拟试验机对20CrMnTi钢在不同温度和保温时间进行了等温膨胀试验,得到其相变热膨胀曲线。结合光学显微镜分析了20CrMnTi钢的等温相变行为,绘制了该钢的等温相变曲线(TTT曲线)。引入Johnson-Mehl-Avrami(JMA)方程和Koistinen-Marburger(KM)方程分别建立了该钢的扩散型相变动力学模型和非扩散型相变动力学模型。结果表明:20CrMnTi钢的TTT曲线呈"双C型",鼻温分别为630和530℃。在730~580℃等温时,奥氏体转变为珠光体+铁素体,随着温度的降低,等温相变速度先加快后减慢;580~430℃等温时,奥氏体转变为贝氏体,随着温度的降低,等温相变速度也是先加快后减慢;低于430℃等温时,奥氏体转变为马氏体,随着温度的降低,马氏体的体积分数先较快增大后减缓。所推导的20CrMnTi钢的动力学模型计算结果与试验结果一致性较好。Isothermal dilatation tests of the 20 CrMnTi steel at different temperatures and holding time were carried out through Gleeble-3500 thermal simulator,and the phase transformation thermal dilatation curves were obtained.Isothermal phase transformation behavior of the20 CrMnTi steel was analyzed by metallographic microscope,and the isothermal phase transformation curve(TTT curve)of the steel was drawn.Johnson-Mehl-Avrami(JMA)equation and Koistinen-Marburger(KM)equation were introduced to establish the diffusion-type and non-diffusion-type phase transformation kinetic models respectively.The results show that the TTT curve of the 20 CrMnTi steel is of"double C"shaped and the nose temperatures are 630℃and 530℃,respectively.At 730-580℃,the austenite transforms into pearlite+ferrite and the isothermal transformation rate first accelerates and then slows down with the decrease of temperature.The austenite transforms into bainite when the steel is held at 580-430℃and the isothermal transformation rate also first accelerates and then slows down with the decrease of temperature.The austenite transforms into martensite below 430℃and the volume fraction of the martensite increases rapidly at first and then slows down with the decrease of temperature.The calculated results of established kinetic model of the 20 CrMnTi steel are in good agreement with the experimental results.

关 键 词：20CRMNTI钢 等温相变 TTT曲线 动力学模型 

分 类 号：TG151.2[金属学及工艺—热处理]