Simulation Of Dynamic Recrystallization Process Of 300M Steel By Cellular Automata Method

300M steel is widely used in the aerospace industry to manufacture a variety of key structural components.Domestic and foreign scholars have carried out a large number of experimental and theoretical studies on the microstructure evolution,and have achieved many results.However,most of these studies focus on the establishment of mathematical models based on experimental data or theoretical models based on physical and chemical mechanisms.There are few studies on microstructure and the evolution of microstructure,which plays an important role in controlling the performance of the workpiece.From the perspective of grain evolution,the microstructure evolution mechanism of high-strength steel is deeply discussed,and the microstructure evolution model is established to realize the accurate simulation of the microstructure evolution process of high-strength steel,which is of great significance for the microstructure control of high-strength steel.Therefore,based on the cellular automata method,the microstructure evolution process of300M steel under different deformation conditions is simulated.The simulation results are analyzed and discussed,and compared with experimental data.Firstly,an isothermal compression experiment of 300M steel was carried out on Gleeble-3500 to obtain the stress-strain curve of 300M steel at strain rate of 0.01¹0s^-1and deformation temperature of 1050¹150°C.Based on the experimental data and regression analysis method,the flow stress model of 300M steel was established,and the material parameters needed to establish the cellular automaton model were extracted.Then,combined with the thermal activation theory,grain boundary curvature driving mechanism and energy dissipation theory in the process of grain growth,the normal growth CA model of 300M steel in the process of heat preservation was established.The CA model was used to simulate the grain growth process under the condition of1050¹150°C.The evolution of grain morphology,growth dynamics,topological statistics and grain size distribution were analyzed and discussed during the growth process.The simulation results were compared with the average grain size obtained from isothermal holding experiment of the 300M steel.The average error was 3.7%.It was observed in the in-situ experiment that the grain growth was achieved by grain boundary migration,which was consistent with the simulated grain growth process and verified the correctness of the model.Finally,the dynamic recrystallization CA model of 300M steel was established by introducing the dislocation density variation model,dynamic recrystallization nucleation and growth model.The dynamic recrystallization initial microstructure was generated by the normal growth CA model.The dynamic recrystallization model was used to simulate the dynamic recrystallization microstructure evolution at strain rate of 0.01¹0s^-1 and deformation temperature of 1050¹150°C,and the effects of different strain,strain rate and temperature on the microstructure evolution were analyzed.The simulation results are similar to those obtained by the thermal compression experiment,and the average grain size error is within 11.844%.It shows that the model can correctly reflect the microstructure evolution process of 300M steel dynamic recrystallization,which can provide a certain guiding role for the 300M steel hot processing technology.