{102}拉伸孪晶对AZ31B镁合金动态力学行为及应变速率敏感性的影响

Effect of {102}Tension Twining on Dynamic Mechanical Behavior and Strain Rate Sensitivity of AZ31B Magnesium Alloy

采用分离式Hopkinson压杆和反射式拉杆装置在室温对挤压态AZ31B镁合金进行了动态压缩和拉伸试验,分析了AZ31B镁合金沿挤压方向压缩和拉伸时的不对称性和应变速率敏感性。结果表明:沿挤压方向压缩时,拉伸孪晶{102}<1120>首先启动,屈服强度对应变速率不敏感;沿挤压方向拉伸时,拉伸孪晶不能启动,位错滑移参与变形,应变速率敏感性有所提高;由于拉伸孪晶只能单向启动,AZ31B镁合金在挤压方向的动态拉压不对称性显著。

Dynamic compression and tension tests of extruded AZ31B magnesium alloy were carried out using a split Hopkinson pressure bar and a reflected hopkinson tension bar apparatus at room temperature.Tension-compression asymmetry and strain rate sensitivity of AZ31B magnesium alloy were analyzed when tested along extruding direction.The results show that when the alloy is compressed along extruding direction,{102}1120 tension twining is initiated first,resulting that the yield stress of the alloy is insensitive to strain rate.When the alloy is tested in tension along extruding direction,{102}1120 tension twining is not initiated,but dislocation slip is responsible for the plastic deformation,resulting that strain rate sensitivity grows.Because of the polarity of tension twining,the tension-compression asymmetry of AZ31B magnesium alloy is much pronounced when tested along extruding direction.