孪生对热轧AZ31镁合金中低温变形行为的影响

Effect of twinning on Moderate-Temperature Deformation Behavior of hot-rolled Mg Alloy

研究了热轧AZ31镁合金板材中低温变形(室温～573K)时孪生所导致的硬化和软化效果,并结合金相显微技术(OM)和透射电子显微技术(TEM)对相关变形机理及孪生类型进行判断。结果发现,有较强基面织构特征的AZ31镁合金板材在室温～573K变形过程中{10ī1}压缩孪晶起主要作用,同时也存在少量的基面滑移。变形温度越高,变形速率越小,孪晶数量也逐渐减少。中低温变形时AZ31镁合金轧制板材中的压缩孪晶和二次孪晶同时起软化作用与硬化作用,但硬化作用大于软化作用。

The softening and hardening effect induced by twinning for the AZ31 hot-rolled Mg alloy sheet in moderate-temperature deformation process（room temperature^573K） were researched carefully.Then,based on optical microscopy（OM） and transmission electron microscopy（TEM）,the deformation mechanism and the type of twinning were explored.The results show that due to the strong texture for the hot-rolled sheet,{1011}contract twins play the insignificant role in moderate-temperature deformation process（RT^573K）,while basal slip also partly affacts the deformation process.With the increase of temperature and decrease of strain rate,the mount of twins also gradually decreases.The dependence of strain hardening index n firstly decreases with the increase of temperature.This indicated that the hardening effect induced by contract twinning is more significant than twinning-induced softening.