| The comprehensive properties of aluminum alloys are mainly determined by microstructure,The microstructure will change and form new deformation microstructure when the material is subjected to thermal and mechanical forces during hot deformation,and dynamic recrystallization usually occurs.The factors affecting microstructure evolution are deformation temperature,strain rate and strain.Therefore,how to control microstructures accurately and improve the comprehensive properties of materials by controlling the deformation parameters has become the key research direction in the field of material processing.The modern aviation industry has put forward higher requirements for the comprehensive properties of high performance aluminum alloys.The comprehensive properties of the large forgings used on the aircraft is more important than the shape during the forming process.It is of great significance to improve the comprehensive properties of materials by studying the microstructure evolution law in the process of hot deformation to precisely control the microstructure of materials.In recent years,with the rapid development of computational materials science,it has become an important research method to simulate the hot deformation behavior of materials by establishing mathematical models.In this paper,7085 aluminum alloy is taken as the research object.The microstructure evolution and macro deformation process are linked by dislocation density,cellular automaton model for simulating the initial microstructure generation and dynamic recrystallization of 7085 aluminum alloy has been established,the microstructure simulation of 7085 aluminum alloy during hot deformation is realized.The main research content is as follows:By Referring to the process parameters of hot deformation experiment of aluminum alloy,the process parameters of thermal simulation test are determined.The experimental temperature range is 300?460 ?,the range of strain rate is 0.001?1 s-1.and the strain range is 0.51?1.5.The specimens are subjected to isothermal compression test on the Gleeble-1500 thermal simulator,and the stress-strain curves are recorded,and the microstructure analysis of the deformed samples is carried out,the average grain size and recrystallization fraction are counted.The stress-strain curves and microstructure evolution of 7085 aluminum alloy under different thermal deformation conditions are studied.According to the physical mechanism of grain growth,four transformation rules have been worked out,and a cellular automata model for simulating the normal growth of grains has been established.The model can output the corresponding initial microstructure according to the average grain diameter.The shape of the grain is equiaxed,and the grain size is basically in line with the normal distribution.The microstructure analysis for homogenized specimens,the initial microstructure obtained by the simulation is in good agreement with the microstructure obtained from the experiment.Based on the distribution function of dislocation density and dynamic recrystallization kinetics equation,a dynamic recrystallized cellular automaton model is established based on the dislocation density.This model can simulate the nucleation and growth process of recrystallized grains.MATLAB language is used to develop the core program of microstructure simulation,and the script program of statistical grain size is developed by Python language.This model is used to simulate the microstructure evolution of different deformation parameters,and the average grain diameter of the microstructure after deformation is calculated.Then the average grain diameter obtained by the microstructure analysis is used to modify the model.The modified model is used to study the effects of deformation temperature,strain rate and strain on the microstructure evolution of 7085 aluminum alloy.The simulation results are verified by Gleeble isothermal compression experiment.The results show that the model can well simulate the process of microstructure evolution during the hot deformation of 7085 aluminum alloy.The average grain diameter and the recrystallization fraction obtained by simulation is consistent with the results of microstructure analysis.It can be used to simulate the dynamic recrystallization of the 7085 aluminum alloy during hot deformation and predict the average grain diameter and recrystallization fraction.The simulation results can provide reference for optimizing the deformation parameters. |
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