Theoretical Model Construction And Simulation Study Based On AZ31 Magnesium Alloy Crystal Plasticity

China’s economic growth at this stage thanks to the transformation and upgrading of China’s automotive industry and 3C and other industries,magnesium alloy with its excellent performance in the manufacturing industry is favored,magnesium alloy industry is very promising market.Magnesium alloy relative specific strength,specific stiffness,small density,elastic model,with good die-casting molding properties,in the process of forming,showing fast heat dissipation,light mass,good rigidity,with a certain degree of corrosion resistance and dimensional stability,impact resistance,wear resistance,good attenuation properties,as well as the continuous progress of magnesium alloy recycling technology,prompting magnesium alloy in the medical chemical,aerospace and other industrial fields to be more widely used.With the development of modern computer science and numerical computation methods,crystal plasticity finite element is regarded as the optimal method to calculate the deformation structure of materials.Crystal plasticity finite element is a combination of crystal plasticity mechanical intrinsic relationship and finite element method to derive the microscopic plastic deformation behaviour of materials from the fine response of grains.The crystal plasticity principal structure relationship attributes plastic deformation of metals to the slip of dislocations and the rotation of the lattice.Compared to the traditional isotropic intrinsic structure relationship,the crystal plasticity mechanics intrinsic structure relationship is closer to the physical nature of plastic deformation of metals.This paper constructs a crystal plasticity model of magnesium alloy with different crystal orientations based on the crystal plasticity theory of AZ31 magnesium alloy for simulation study,and explores the anisotropy and tensile asymmetry caused by different crystal orientations during the plastic deformation of AZ31 magnesium alloy through the combination of room temperature uniaxial compression experiments and tensile experiments by electron backscatter diffraction,as well as the relationship between the weave evolution pattern,twinning and mechanical properties of magnesium alloy in the plastic deformation process,to provide a theoretical basis for processing and development of magnesium alloy.The main findings are as follows:(1)The crystal plastic deformation behavior depends largely on the initial crystal orientation,and the differences in different initial crystal orientations lead to anisotropy in the plastic deformation behavior of magnesium alloy,with low radial yield and tensile strengths and high axial yield and tensile strengths.(2)During the plastic deformation of AZ31 magnesium alloy,with the increase of strain,the volume fraction of twin activation is also increasing,because different loading directions lead to different rotation of grain c-axis,twinning is suppressed in axial plastic deformation,the volume fraction of twin activation is low,twinning is extremely easy to produce in radial plastic deformation,the volume fraction of twin activation is high.(3)The activation of twins leads to a significant change in the evolution of the weave.The higher the volume fraction of twin activation,the larger the polar density shift of the weave,and the higher the number of radial twin integrals,the larger the polar density shift of the radial weave.(4)During the plastic deformation of AZ31 magnesium alloy,the point where obvious twinning occurs coincides with the point of abrupt stress change,when the number of twin crystal integrals reaches a certain value,the stress changes abruptly,at which time the crystal orientation changes and a new slip system is initiated,reflecting the influence of the coupling of slip and twinning mechanism on the mechanical properties.