Hot Deformation Behaviour And Microstructure Evolution Of 20crMnTiH

With the development of manufacturing, people focus more on good performace than just ensuring the shape precision of parts. At present, many scholars are very interested in the metal precisinon forming technology because of it's such some advantages as the higher shape precision and the better performance for the finished part. The mechanical behavior and evolution of microsturcture for metal play an important role in determining the performance of the finished parts, so it is significant for theory research and practical application to understand and simulate the microstucture evlution during precision forming. However, the material microstructure simulation prediction module of many simulation software is not complete. Therefore, 20 CrMnTi H steel is studied in this paper, the influence of different technical parameters on the material flow stress behavior and microstructure is investigated, and the mathematic models are established. And the DEFORM-3D software is redeveloped to simulate the microstructure evolution of 20 CrMnTiH steel during hot compression, which provides the basic for optimization of technological parameter and improve the parts performance.The main research contents and conclusions of the paper are summarized as follows:(1) The isothermal holding experiments, the single pass and double pass thermo-simulation compression experiments are conducted on the Gleeble-3500 thermo-simulation system. The influence of deformation process parameters on flow stress behavior is analyzed by studying the stress-strain curves. By the means of mathematical algorithm, the flow stress model, the kinetic and kinematics model of dynamic recrystallization, the kinematics model of static recrystallization, and the kinematics models of meta-dynamic recrystallization are obtained.(2) After the isothermal holding experiments and compression experiments, the quenched specimens are cutting, inlaid, polished and etched. Then the microstructure on the section plane of specimens are examined and analyzed under the optical microscope. The influence of deformation process parameters on microstructure is analyzed by studying metallography. By the means of mathematical algorithm, the austenite grain growth model, the grain size model of dynamic recrystallization, static recrystallization and meta-dynamic recrystallization are obtained.(3) The DEFORM-3D software is redeveloped through the user subroutines and. Compiling program of microstructure evolution of 20 CrMnTiH steel using Absoft Fortran software, than embedded the program in DEFORM-3D software.(4) The numerical simulation of the above experiment process is carried out by the redeveloped DEFORM-3D. The influences of the process parameters on microstructure are discussed. The comparison of experimental results and simulation results shows the responsibility of the redeveloped DEFORTM-3D.