AZ31镁合金棒材循环扭转过程中的力学性能和织构变化

Mechanical Properties and Texture Evolution of Extruded AZ31 Magnesium Alloy Rods Under Cyclic Torsion

对AZ31镁合金挤压棒材在循环扭转变形过程中的力学性能和织构演化进行了研究。循环扭转变形分别在298,373,443,503和573 K下进行。镁合金循环变形的力学性能测试结果表明,循环扭转变形过程的应力应变滞回线呈现严格的对称性,意味着微观变形模式以滑移为主。变形过程的热效应使应力应变曲线中的峰值应力随着周期数的增加而降低。变形过程中柱面滑移系启动使晶粒取向发生改变,由变形前的{11■0}⊥ED织构转变为变形后的{10■0}⊥ED织构,变形过程中拉伸孪晶启动使晶粒取向产生两种变化。

This paper investigated the mechanical properties and texture evolution of extruded AZ31 magnesium alloy rods under cyclic torsion.Thus,cyclic torsion tests were performed at different temperatures such as room temperature,373,443,503,and 573 K.Measured mechanical properties of magnesium alloy cyclic torsion reveal that stress-strain hysteresis loops of cyclic torsions are strictly symmetric which means that the dominant deformation mechanism is sliding.Additionally,due to the thermal influence of cyclic torsion,the peak stresses in stress-strain hysteresis loops are decreased with the increase in cycle number.The grain orientations are changed due to the activation of prismatic slips.The texture of{11■0}prismatic planes perpendicular to ED in initial rods is transformed into the texture of{10■0}prismatic planes after cyclic torsion.Also,two types of grain orientation variations occur because of the activation of extension twin.