C-Mn钢连续冷却转变及相变动力学模型优化  

Optimisation of continuous cooling transformation and phase transition kinetics model for C-Mn steels

作　　者：王志豪 李红斌 刘会群[1] WANG Zhihao;LI Hongbin;LIU Huiqun(School of Materials Science and Engineering,Central South University,Changsha 410083,Hunan,China;College of Metallurgy and Energy,North China University of Science and Technology,Tangshan 063210,Hebei,China)

机构地区：[1]中南大学材料科学与工程学院,湖南长沙410083 [2]华北理工大学冶金与能源学院,河北唐山063210

出　　处：《钢铁研究学报》2025年第1期117-126,共10页Journal of Iron and Steel Research

基　　金：河北省自然科学基金资助项目(E2022209049,E2020209040)。

摘　　要：C-Mn钢相变动力学方程的构建,对其微观组织调控和力学性能提升具有重要的指导意义。使用Gleeble-3500热模拟实验机、光学显微镜(OM)、场发射扫描电镜(SEM)等对C-Mn钢进行连续冷却转变行为研究,并基于相变产物对传统JMAK方程进行优化。结果表明:C-Mn钢经1000℃完全奥氏体化后以0.5~50℃/s的速率冷却,随着冷却速率v的不断增大,过冷奥氏体先后经历铁素体、珠光体、贝氏体和马氏体相变,当冷却速率大于20℃/s时,组织为全马氏体,且对应转变温度区间分别为728~516℃、517~400℃和330~190℃。当冷却速率增大时,相变产物转变临界时间跨度t_(0)以指数形式减小,经指数拟合得t_(0)=120.6 v^(-0.83)。基于不同相变产物对晶粒生长指数n值的影响规律,建立不同冷却速率下n值关于冷却速率的函数关系式并构建了JMAK相变动力学方程。模型预测精度得到提升,对于JMAK方程在描述非等温快速冷却条件下多相转变过程具有一定推动作用。The construction of kinetic equations for the phase transition of C-Mn steels is of great significance in guiding its microstructure regulation and mechanical property enhancement.Continuous cooling transformation behavior of C-Mn steel was investigated by Gleeble-3500 thermal simulator,optical microscope(OM),field emission scanning electron microscope(SEM).The conventional JMAK equation was optimized based on the phase transformation products.The results show that the C-Mn steel was cooled at a rate of 0.5-50℃/s after complete austenitising at 1000℃.With the increasing cooling rate,the supercooled austenite undergoes the phase transformation of ferrite,pearlite,bainite and martensite successively.The organisation is fully martensitic when the cooling rate is greater than 20℃/s and the corresponding transformation temperature intervals are 728-516,517-400 and 330-190℃.When the cooling rate increases,the critical time span t_(0) of the phase transition product transformation decreases exponentially,with an exponential fit as t_(0)=120.6 v-0.83.Based on the influence of different phase transition products on the n value,the functional equation of the n value on the cooling rate was established under different cooling rates.The kinetic equations for the JMAK phase transition were constructed.Eventually,model prediction accuracy has been improved.The JMAK equation has a driving role in describing the multiphase transformation process under non-isothermal rapid cooling conditions.

关 键 词：C-MN钢 连续冷却转变 微观组织 CCT曲线 JMAK方程 

分 类 号：TG142.1[一般工业技术—材料科学与工程]