The Finite Element Simulation On Plastic Behavior Of Pure Titanium

Based on Crystal Plasty Finite Element Method (CP-FEM) and Voronoi diagram, the poly-crystal plasticity finite element model of single crystalline and polycrystalline materials of TA2 pure titanium is set up. And the deformation behavior of crystal from the microscopic view was researched by this finite element model.The tensile deformation behavior of single crystalline was studied firstly and the results show that the rotation of orientation occurred at the same time with the tensile deformation of single crystalline and the slip direction of slip-systems could gradually parallelled with the tensile direction.Influence of orientation factors during uniaxial tension of single crystal metal is studied using the model of single crystalline. The results show that different orientation factors have contributed to the yield strength and tensile stress during plastic deformation. With the orientation factor reduced, the yield sress of single crystalline becomes lower, which accords with Schmid's law.Compare the results of the model of single crystalline with the results of the actual material tensile tests, the change of metallographic structure and the tensile curve from simulation analysis results are well in agreement with that of experment. The relationship between the deformation course,the morphology of microstructures and the stress was analyzed, the evolution of stress and strain of polycrystalline deformation were catalyzed, the stress and strain distributions in elastic stage,plastic stage,hardening stage and the necking stage were described. The inhomogeneity of micro mechanism of plastic deformation of polycrystalline was described in detail. According to the inhomogeneity micro mechanism, the formation mechanism of tangerine peel is investigated.The influences of the different grain size to the behavior of the plastic deformation of polycrystalline were analyzed. The yield stress increased with the decreasing of the size of crystal grains, the hardening curve began to climb quite steeply and the maximum tensile stress increased. The increasing rule accord with Hall-Petch's law, the predictive factors of TA2 titanium by simulation areσ0=64.9MPa,K=473.3MPaμm1/2. The influences of the initial texture to the anisotropy of the polycrystalline deformation were researched using the method of setting the texture model of same orientation grains. The results show that with the increasing of the strength of texture, the inhomogeneity of the deformation of polycrystalline increased, the yield stress also increases, the hardening curve began to climb quite steeply and the maximum tensile stress increased.