Numerical Simulation Of Hot Deformation Behavior And Microstructure Evolution Of TC4 Titanium Alloy

As one of the preferred materials for aero-engine blades,TC4 titanium alloy has many excellent characteristics.However,its microstructure evolution is complicated,and only the microstructure that meets the performance can meet the requirements of the comprehensive performance of the workpiece in production.At present,the prediction of the microstructure of TC4 titanium alloy is mostly concentrated in the β phase region.However,the prediction of microstructure in α+β biphasic region is relatively less.Therefore,the hot deformation behavior and microstructure evolution law of TC4 titanium alloy during processing in the dual-phase region were studied,and the relevant content of the microstructure evolution theory during processing in the dual-phase region was improved:The thermal deformation behavior under different deformation conditions is analyzed by hot compression test,and the Johnson-Cook constitutive model is established using the corrected data.The thermal processing map and thermal processing window are established,and the macrostructure and microstructure of the specimen are observed for verification.The optimal processing parameter interval is selected : T=820℃～850℃,ε = 0.001 s ～0.018 s and T=850℃～900℃,ε = 0.018 s ～0.025 s.The dynamic recrystallization volume fraction model and grain size model were established.The accuracy of the model is verified by the combination of finite element simulation and experiment and it is determined that the finite element model can describe the thermal deformation behavior in the process of thermal compression.A cellular automata model of dynamic recrystallization process is established,and the influence rule of dynamic recrystallization is analyzed.The results show: The higher the temperature and the smaller the strain rate,the more complete the recrystallization,and the larger the average grain size.It is verified by EBSD experiment,by analyzing the grain boundary angle and misorientation distribution,it is demonstrated that dynamic recrystallization is promoted when the temperature is increased and the strain rate is decreased.Figure 60;Table 9;Reference 69...