Simulation Of Dynamic Recrystallization Process Of Cr12MoV Steel By Cellular Automata Method

In the process of metal hot forging,the grain normal growth and recrystallization process is an important process to determine its final forming properties.How to study the dynamic recrystallization behavior of material and determine the influence of strain,strain rate and deformation temperature on the microstructure evolution of hot forging process has become one of hot research directions in recent years,establish a simulation model which can describe the process of recrystallization microstructure more accurately is a difficult problem in this field.In this paper,the recrystallization behavior of Cr12 MoV steel during hot forging was studied by means of cellular automata(Cellular Automata)and the microstructural evolution result of Cr12 MoV steel were predicted.The simulated results are compared to experimental results finally.Firstly,Cr12 MoV steel was subjected to isothermal compression test under different forming conditions using Gleeble-3500 thermal simulation machine.The mathematical model of material flow stress is established according to the experimental results.Also,the material parameters of the dynamic recrystallization CA model were obtained by mathematical analysis of the characteristic points of the material flow stress curve.Secondly,according to the grain boundary migration thermodynamic mechanism,grain boundary stability condition and grain growth dynamics theory,a CA model which can simulate the grain normal growth is established.By using the model,the effect of temperature on the grains normal growth was analyzed.The simulation results of the grain normal growth were verified by topological statistics and kinetics.On this basis,by the further introduction of the theory of material recrystallization nucleation and growth mechanism and dislocation density change theory,the dynamic recrystallization CA model of Cr12 MoV steel was established.The effect of strain,strain rate and deformation temperature on the microstructure evolution of recrystallization was investigated.Also,the recrystallization kinetics was analyzed.Finally,the simulation results were compared with the microstructure picture obtained by the Cr12 MoV steel hot compression experiment.The difference between the flow stress curve calculated by the CA model and the flow stress curve obtained from the hot compression experiment was investigated.The results show that the grain normal growth model CA can correctly reflect the feature of the grain normal growth,and the simulated growth index is consistent with the grain normal growth theory.The dynamic recrystallization CA model of Cr12 MoV steel can describe the microstructure evolution feature of dynamic recrystallization process accurately and intuitively,and compared to experimental results,grain size error is within 10.2%.And the flow stress curve calculated from the mean dislocation density of the cell spatial is in good agreement with the flow stress curve obtained by the hot compression experiment.The CA model can accurately reflect the dynamic recrystallization kinetics characteristics and predict the dynamic recrystallization microstructure of Cr12 MoV steel during hot forging process,which can give reference for industrial production process setting.