(沈阳工业大学 材料科学与工程学院，辽宁省镁合金及成形技术重点实验室，沈阳 110870)
摘 要: 采用分离式霍普金森压杆(SHPB)测试预孪晶AZ31镁合金板材在应变速率分别约为800、1200和1600 s-1时的动态真应力-真应变曲线。通过自编程软件及电子背散射衍射(EBSD)技术分析预孪晶试样在高应变速率前后微观组织和织构的演变。结果表明：沿横向(TD)预压缩后再沿着轧制方向(RD)复合预压缩可促进AZ31镁合金板材中多孪晶变体及二次拉伸孪晶的激活。对于沿TD方向一次预压缩的试样，其法向(ND)高应变速率下的屈服强度急剧下降，这主要是由于退孪生的启动。然而，对于沿TD+RD复合预压缩试样，由于 - 二次孪晶和大量交叉孪晶变体的形成可以有效抑制退孪生行为，一定程度上提高了AZ31镁合金ND方向的屈服强度，并且拉伸孪晶的形成能够便利于启动更多的滑移系，改善了镁合金板材ND方向的塑形变形行为。
关键字: AZ31镁合金；孪生；织构；高应变速率；变形机制
（School of Materials Science and Engineering, Key Laboratory of Magnesium Alloys and the Processing Technology of Liaoning Province, Shenyang University of Technology, Shenyang 110870, China）
Abstract:The high strain rates compressive behavior of AZ31 magnesium alloy sheet along ND was measured by split Hopkinson pressure bar (SHPB) at strain rates of 800, 1200 and 1600 s-1. The microstructure and texture evolution of pre-twinning samples, including prior and after high strain rates compressive deformation, were analyzed by electron back-scatter diffraction (EBSD) and self-made software. The results show that the pre-twinning AZ31 magnesium alloy sheet along transverse direction (TD) and then rolling direction (RD) can promote the activation of multiple twin variants and double twins. For the samples of pre-twinning along TD, the compressive yield strength along ND of high strain rates decreases due to the occurrence of de-twinning. However, for the samples of pre-twinning along TD then RD, the formation of - double twinning and a large number of cross-twins lamellas inhibit the de-twinning behavior and enhance the yield strength of magnesium alloy along ND. Further more, the formation of extension twinning contributes to initiate more slip systems and improves the deformation behavior of AZ31 magnesium sheet along ND.
Key words: AZ31 magnesium alloys; pre-twinning; texture; high strain rate; deformation mechanism
