AZ31镁合金轧制板材各向异性行为的晶体塑性研究

Study on anisotropic mechanical behavior of AZ31 Mg alloy sheet based on crystal plasticity modeling

室温下,镁合金的主要变形机制是滑移和孪生相互竞争。为了从介观尺度准确描述这种变形机制,晶体塑性本构关系需要考虑滑移和孪生的耦合作用。基于滑移-孪生耦合的晶体塑性本构关系,本文采用代表体积单元法建立了多晶模型,并对AZ31镁合金沿RD和TD方向进行拉伸模拟分析。结果表明:沿RD方向的变形机制为基面滑移、柱面滑移、锥面滑移,沿TD方向为柱面滑移和锥面滑移。沿不同方向基面滑移对变形的贡献不同,造成AZ31镁合金轧制薄板沿RD方向的屈服强度小于TD方向,表现出强烈的力学性能各向异性。

The deformation mechanism of Mg alloy at room temperature is described by the competition of dislocation slip and twinning.In order to analysis this deformation mechanism at meso-scale, combined effects with dislocation slip and twinning should be taken into account in crystal plasticity modeling. Therefore, based on crystal plasticity model combined with slip and twinning effects, a polycrystalline model was built based on Representative Volume Element （RVE） method and simple tension along rolling direction （RD） and transverse direction （TD） of AZ31 rolling sheet was discussed.It is found that basal slip, prismatic and pyramidal slips are the main deformation mechanism along RD direction, while prismatic and pyramidal slips along TD direction.Different contribution of basal slip to the deformation leads to the strong anisotropic behavior, lower yield strength along RD than that along TD direction.