Study On Dynamic Recrystallization Behavior Of Rare Earth Magnesium Alloy During Hot Deformation And Cellular Automata Simulation

Rare earth magnesium alloys have high strength,low density,good seismic and noise reduction performance,good damping and other excellent characteristics,and have become a research hotspot in the fields of aviation,weapon equipment,automobile,electronic communication and so on.Plastic deformation is an important processing method to improve the performance of key components of rare earth magnesium alloys.The properties can be improved only by controlling the evolution of microstructure through plastic processing.Cellular automata(CA)method can process data in parallel,has high computational efficiency,and can more truly simulate the grain growth and recrystallization process.The simulation results can directly reflect the microstructure evolution process.It is one of the most widely used simulation methods in the field of material microstructure at present.In this paper,the hot compression test of Mg-13Gd-4Y-2Zn-0.5Zr alloy was carried out.The characteristics of flow stress curve and microstructure evolution under different deformation temperature and deformation rate were analyzed.An improved CA model with lpso phase influence factor was established and verified by experiments.Combining the numerical simulation of thermal stress and strain field with CA model,the dynamic recrystallization phenomenon of the alloy during hot deformation was predicted by using finite element simulation technology,and the visualization of micro evolution law was realized.The thermal compression parameters are 0.001?1s-1,350?470 ?,and the total strain is about 60%.The thermal compression curve has gone through three stages: linear hardening,rheological softening and dynamic equilibrium.The results show that the flow stress and peak stress increase with the increase of strain rate and the decrease of temperature.Finally,the Arrhenius type constitutive equation is constructed from the thermal compression curve.In the constitutive equation,strain has an important effect on the activation energy of thermal deformation,and the relationship between them is fitted by polynomial.Therefore,a constitutive model of the effect of strain on thermal deformation behavior is established.The relationship between dynamic recrystallization mechanism and deformation conditions of Mg-13Gd-4Y-2Zn-0.5Zr under different hot compression parameters was studied.At the same time,the microstructure of the hot compression process was observed,and the effects of different hot compression parameters on the microstructure were analyzed.With the increase of deformation temperature and the decrease of strain rate,the volume fraction of dynamic recrystallization and the average grain size of dynamic recrystallization increase gradually.The L-J dislocation density change model,Roberts dynamic recrystallization nucleation model and recrystallization growth model are introduced to construct a CA model that accurately reflects the dynamic recrystallization evolution law of the alloy.The grain module in DEFORM-3D was redeveloped by FORTRAN language,and the microstructure evolution of rare earth magnesium alloy under different deformation parameters was simulated.The maximum error of dynamic recrystallization volume fraction is 12.39%,and the minimum error is 7.78%.The maximum error of average grain size is 9.63%,and the minimum error is 6.06%.