初始织构对AZ31镁合金孪生和织构演化的影响

为研究AZ31镁合金变形孪晶和塑性各向异性，基于率相关晶体塑性本构理论，采用有限元方法建立了具有不同初始织构的镁合金模型（包含滑移和孪生变形机制），并引入孪晶体积分数，研究其压缩过程中织构演变、孪生和力学性能之间的关系。结果表明：晶体的塑性行为在很大程度上取决于初始织构，初始织构的差异导致了压缩行为的明显各向异性，轴向屈服强度和抗拉伸强度高，径向屈服强度和抗拉伸强度低。压缩塑性变形过程中随着变形量的增加，激活孪晶体积分数增高，且径向压缩激活孪晶体积分数越高，轴向压缩激活孪晶体积分数越低。模拟中出现明显孪晶的点与应力突变的点相吻合，当孪晶体积分数达到一定值时，应力发生突变，此时晶体取向发生显著变化，新的滑移系启动，反映了滑移和孪晶机制耦合对AZ31镁合金力学性能的影响。

Effect of Initial Texture on Twinning and Texture Evolution of AZ31 Magnesium Alloy

To study the deformation twins and plastic anisotropy of AZ31 magnesium alloy, based on the plastic constitutive theory of rate-correlated crystals, a magnesium alloy model with different initial textures, including slip and twin deformation mechanisms, was established by the finite element method. Besides, the volume fraction of twin crystals was introduced into the model. The relationship among texture evolution, twins, and mechanical properties during compression was studied. Results show that the plastic behavior of crystal depends largely on the initial texture, and the difference in the initial texture leads to the obvious anisotropy of compression behavior: high axial yield and tensile strength and low radial yield and tensile strength. During the compressive plastic deformation process, with increasing the deformation, the volume fraction of activated twin crystal is increased. In addition, the higher the volume fraction of radial compressive activated twin crystal, the lower the volume fraction of axial compressive activated twin crystal. The points of obvious twin crystal appearance in the simulation coincide with those of stress mutation. When the volume fraction of twin crystal reaches a certain value, the stress suddenly changes, the crystal orientation changes significantly, and the new slip system is activated, reflecting the influence of the coupling of slip and twin crystal mechanisms on the mechanical properties of AZ31 magnesium alloy.