Computer Simulation and Control of Microstructure and Mechanical Properties in Hot Forging.pdfVIP

Computer Simulation and Control of Microstructure and Mechanical Properties in Hot Forging Zhe Wang, Takashi Ishikawa, Nobuki Yukawa, Akira Kono, Yasuhisa Tozawa (1) Dept. of Materials Processing Engineering, Nagoya University, Nagoya, Japan Receivedon January 10,1999 An analytical procedure for predicting the microstructureand mechanical properties of forged microalloyed steels is presented. Empirical relationships between recrystallizedgrain size, temperature and strain as well as the relationship between austenite grain size and ferrite grain size are obtained. These relations are ex- pressed as an incrementalformula and incorporated into thermo-coupled FEM code. By applying this analysis to practical multiple stage hot forging of flange companions or automotive parts made of microalloyedsteel, the microstructure and hardness of forged parts can be predicted. The results of these predictions are in good agreement with the experimental results.The simulation is used to investigatethe therrno-mechanical pro- cesses for forging functional parts with partially fine grain and high hardness. Keywords: Hot Forging, Property prediction, FEM IINTRODUCTION The specimenswere machinedfrom round bar stock into Thermo-mechanical forming is not only a forming process cylinders 1Omm in diameter and 15mm high. They were but also a processfor improving material properties by con- upset at various temperatures and strains using a 100-tonf trolling recrystallization, recoveryand phase transformation. mechanical press with an induction heater and then cooled The ability to predict and control the microstructure and at various cooling