Study On The Anisotropy Of Mechanical Behavior And Deformation Mechanisms Of AZ31 Mg Alloys By Numerical Simulation

Magnesium alloys have drawn great interest in recent years due to their excellent mechanical properties such as high specific strength and superior damping capacities. However, magnesium alloys exhibit limited room temperature ductility and poor cold workability which have been attributed to that deformation modes other than the basal slip and twinning are difficult to activate at low temperature.It has been an important and difficult area for the researchers to find out the influence of slip and twinning systems on the texture evolution. Uniaxial test was conducted to determine the material parameters of self-consistent model established in this paper studying the macroscopic mechanical behavior and micro mechanical mechanisms.Texture evolution during cold rolling was also conducted in this paper to study the influence of micro deformation mechanisms.Uniaxial test was conducted to determine the material parameters of self-consistent model established in this study researching the macroscopic mechanical behaviors and micro mechanical systems.Hot rolled Mg alloy sheet is often with strong basal texture. Macroscopic mechanical behavior along different loading direction was precisely achieved with self-consistent model and the anisotropy of mechanical behavior properties was resulted from the different CRSS of mechanisms and how it contributes. Basal and prismatic slip systems dominate in the early stage along rolling direction, however, pyramidal slip system comes into domination in the late stage of plastic deformation. Tensile twinning was the main deformation mechanisms along the normal direction. Basal slip was hardly activated along normal direction with extremely low schmid factor. Yield strength was smaller than that of other directions.Analysis of lattice strain of different planes along three uniaxial loading directions reveals anisotropy of micro lattice strain.Lattice strain was equal in the elastic stage until it comes to the plastic stage, where different planes reveal "soft" and "hard", relatively. (0002) becomes the softest and(1011) the hardest between 150-225MPa (loading stress).While (0002) becomes the hardest and (1011) turns the softest after 225MPa.Contribution of different mechanical mechanisms was studied by setting different material parameters. Results show that the CRSS of basal and prismatic slip systems determine the yield strength along RD direction. The hardening rate of material decreases with the increase of CRSS of basal slip. The hardening rate of material increases with the increase of CRSS of prismatic slip system. Pyramidal slip dominates late plastic stage of deformation and the hardening rate increases with the increase of CRSS of pyramidal slip making the stress-strain curve higher.Texture evolution of cold rolling of AZ31 Mg alloys was successfully simulated by self-consistent model. Tensile twinning was hardly activated in 90 degree sample with strong basal texture and slip systems become the dominate modes Strong-texture points of initial pyramidal texture outskirt the center of pole figure with intensity of texture decreasing. Tensile twinning was activated in 45 degree sample in simulation and results in the reorientation of grains which contributes to the activation of basal and prismatic slip systems.