Modeling and Simulation of Iron-Carbon Phase Transformation During Tempering of Steel  

作　　者：Dong-ying Ju1,Xiao-hu Deng 2 1Department of Mechanical Engineering,Saitama Institute of Technology,Saitama,Japan 2 Advanced Science Research Laboratory,Saitama Institute of Technology,Saitama,Japan 

出　　处：《稀有金属材料与工程》2012年第S1期6-12,共7页Rare Metal Materials and Engineering

基　　金：support by the High-tech Research Center and Open Research Center at the Saitama Institute of Technology

摘　　要：Tempering is final process used in heat treatment of steel components.It is important to improve the toughness and ductility of the quenched steel without a great loss of the hardness and strength.However,the traditional tempering process is hard to satisfy requirements of combination mechanical properties with low cost.A quantitative model is developed to simulate the micro-structural evolution during tempering process of carbon steel by modifying the previous Ju and Inoue's model.The model takes into account tempering parameters,carbon content and morphology for iron-carbon phases.Segregation of carbon atoms,precipitation of transition carbides(ε-carbide),decomposition of retained austenite and precipitation of cementite can be predicted respectively.The precipitation of carbides is modeled by considering the competitive precipitations ofε-carbide and cementite.The kinetics of decomposition of retained austenite into ferrite and cementite is depicted by the modified Avrami equation.To validate the model,it is applied to simulate the tempering process of the as-quenched plain carbon steel.The volume fractions of iron-carbon phase are calculated at different tempering temperature and time.It is indicated that tempering time has greater effect on the volume fraction of carbides at high temperature stage.The calculated results are reasonable consistent with the theoretical descriptions.Tempering is final process used in heat treatment of steel components.It is important to improve the toughness and ductility of the quenched steel without a great loss of the hardness and strength.However,the traditional tempering process is hard to satisfy requirements of combination mechanical properties with low cost.A quantitative model is developed to simulate the micro-structural evolution during tempering process of carbon steel by modifying the previous Ju and Inoue’s model.The model takes into account tempering parameters,carbon content and morphology for iron-carbon phases.Segregation of carbon atoms,precipitation of transition carbides(ε-carbide),decomposition of retained austenite and precipitation of cementite can be predicted respectively.The precipitation of carbides is modeled by considering the competitive precipitations ofε-carbide and cementite.The kinetics of decomposition of retained austenite into ferrite and cementite is depicted by the modified Avrami equation.To validate the model,it is applied to simulate the tempering process of the as-quenched plain carbon steel.The volume fractions of iron-carbon phase are calculated at different tempering temperature and time.It is indicated that tempering time has greater effect on the volume fraction of carbides at high temperature stage.The calculated results are reasonable consistent with the theoretical descriptions.

关 键 词：TEMPERING phase transformation kinetics transition CARBIDE CEMENTITE 

分 类 号：TG156.5[金属学及工艺—热处理]