Hot Deformation Behavior Of V-10Cr-5Ti Alloy And Numerical Simulation On Microstructural Evolution Of Dynamic Recrystallization

Dynamic recrystallization(DRX)is a type of recrystallization process during hot plastic deformation.DRX is an effective approach to refine grains,control texture and improve plastic deformation capacity.The information of microstructure can't be obtained quantificationally through the traditional theoretical and experimental method.Cellular Automaton(CA)is an simple,efficient and realistic simulation method.Therefore,it was been widely used in the simulation of microstructure evolution of metallic materials.V-10Cr-5Ti alloy possesses machinability,high strength and low thermal expansion.Additionally,it possesses good resistance to irradiation,hydrogen embrittlement and high temperature,which was considered as the candidate structural materials for fusion reactor.However,the grains of casting is large,which has a negative effect on mechanical properties.In this research,CA method was used to simulate the microstructural evolution during hot processing.Besides,the DRX behavior of V-10Cr-5Ti was studied.The main work is as follows:The true stress-strain curves were obtained during hot deformation tests at temperature of 950~1350 ? and strain rates of 0.01~10s-1.The hot deformation behavior of this alloy was investigated.A strain compensated Arrhenius constitutive model was established and the prediction accuracy was evaluated.The results show that the constitutive model has a good accuracy and can be applied to simulate the microstructural evolution.The CA models coupled with the internal rules in the process of DRX were constructed including the principles of thermal activation,grain boundary migration,curvature driven and energy dissipation.Then write and debug the program to generate the initial grain structure.And the simulated results are in accordance with the experimental ones,which indicated that the CA model has a good accuracy and applicability.Those are the necessary prerequisites for the subsequent study of the DRX of V-10Cr-5Ti alloy.The topology model of V-10Cr-5Ti alloy was established during hot deformation.The simulated microstructures agreed well with the three deformation zones in the specimen.The morphology of grains in different deformation zones were analyzed in detail.Based on physical knowledge of dynamic recrystallization,CA models of DRX process were developed,including the dislocation density model,nucleation model,grain growth model and critical dislocation density model.Then the corresponding program was wrote,debugged and optimized.In order to verify its simulated accuracy,the results of experimental and predicted were compared at different deformation conditons.The error is small and acceptable,which indicates that the CA model can be well used to predict the microstructural evolution of V-10Cr-5Ti alloy.The effect of different initial grain sizes,deformation temperatures,strain rates and strains were researched.The microstructural evolution behavior and mechanisms were analyzed.