Simulation Of Microstructure Evolution Of Ti40Alloy During Hot Forming Process

During hot deformation process of metal, a chain of complex changes willhappen on its microstructure. These will affect the materials processing technologyand comprehensive performance of the product directly. Ti40alloy has a broadapplication prospect in aviation because of its good flame retardant performance. Butits organization and properties are sensitive to deformation process parameters andhave poor plasticity, which is hard to get the stable and good products. Therefore，ithas a far-reaching significance and practical value to the forming technology of thematerials through studying evolvement rule of materials during hot forming.In this paper, isothermal and constant strain rate compression tests on the Ti40alloy are carried out in true strain range of0~0.92, deformation temperature range of950~1100℃and strain rates range of0.001~0.1s-1by using the Gleeble hot workingsimulator. The microstructure evolution of Ti40alloy compression samples underdifferent process parameters is studied by metallographic microscope. The resultsindicate that dynamic recrystallizaiton behavior proceed more sufficiently with theincreasing deformation temperature (950~1100℃) at constant strain rate. At constantdeformation temperatures, when the strain rate reduced from0.1to0.001s-1, thedynamic recrystallization volume fraction and grain size increased significantly. Atconstant deformation temperatures and strain rate, the dynamic recrystallizaitonbehavior also proceed more sufficiently with the increasing true strain (0~0.92).Based on the microstructure evolution research of Ti40alloy compressionsamples, the JMAK dynamic recrystallization models are set up (Recrystallizationvolume fraction model, recrystallization grain size model and average grain sizemodel). The alloy compression process simulation is carried out on the DEFORM-3D,the simulation results show that:(1) In different areas of the sample, the highesteffective strain, strain rate and temperature are appeared in the central area;(2)Different process parameters have different effects on the dynamic recrystallization,which showed that the larger strain, lower strain rate and higher deformationtemperature would contribute to the DRX happening;(3) The values ofrecrystallization volume fraction and recrystallization grain size by the JMAKdynamic recrystallization model are close to the experimental results. Dynamic recrystallization models are established through cellular automatatheory. Using the microstructure module from the DEFORM-3D simulate the samplemicrostructure evolution in the process of hot compression. And analyse these factorssuch as deformation temperature, strain rate and strain how effect on dynamicrecrystallization. The results prove that (1) The dynamic recrystallization is occuredduring hot compression, which leads the grains can be refined and the microstructureperformance can be improved greatly.(2) Larger strain, lower strain rate and higherdeformation temperature will make the dynamic recrystallization more fully.(3)Simulation of microstructure evolution regularity has high consistency with theexperimental results.Based on the experiment results, which can illustrate the accuracy of JMAKdynamic recrystallization models and cellular automata dynamic recrystallizationmodels. Not only that, the research results will offer a good method to understand thealloy in forming technology.