高速冲击载荷下预压缩AZ31镁合金的退孪生行为与动态力学性能  

Detwinning Behaviors and Dynamic Mechanical Properties of Precompressed AZ31 Magnesium Alloy Subjected to High Strain Rates Impact

作　　者：陈扬 毛萍莉[1] 刘正[1] 王志[1] 曹耕晟 CHEN Yang;MAO Pingli;LIU Zheng;WANG Zhi;CAO Gengsheng(Key Laboratory of Magnesium Alloys and the Processing Technology of Liaoning Province,School of Materials Science and Engineering,Shenyang University of Technology,Shenyang 110870,China)

机构地区：[1]沈阳工业大学材料科学与工程学院辽宁省镁合金及其成型技术重点实验室,沈阳110870

出　　处：《金属学报》2022年第5期660-672,共13页Acta Metallurgica Sinica

基　　金：辽宁省兴辽英才计划项目No.XLYC1908006。

摘　　要：为研究高应变速率冲击载荷下预压缩轧制态AZ31镁合金的退孪生行为与动态力学性能,将原始试样沿轧制方向(RD)进行真应变为4%的准静态预压缩,引入大量的{1012}拉伸孪晶。利用分离式Hopkinson压杆(SHPB)装置对原始及预压缩AZ31镁合金样品沿板材法向(ND)进行应变速率为700、1000、1300和1600 s;的高速冲击实验,并利用EBSD技术对原始试样、预压缩试样以及不同应变速率下的冲击试样进行微观组织分析。结果表明,相比于原始试样,预压缩AZ31镁合金试样内的基面织构强度明显减弱并形成c轴与RD平行的孪晶织构,由于拉伸孪晶界对母晶粒的分割作用使得平均晶粒尺寸明显降低。预压缩AZ31镁合金试样沿ND高速冲击时的主要变形机制为退孪生,随着冲击应变速率的增大,孪晶织构逐渐恢复至初始的强基面织构,孪晶面积分数和孪晶平均厚度均逐渐降低,平均晶粒尺寸逐渐增大。此外,沿ND冲击原始试样相比于预压缩试样具有更高的强度和更低的塑性,且在塑性变形过程中预压缩试样呈现出更加明显的应变速率敏感性。To investigate the detwinning behaviors and dynamic mechanical properties of a precompressed rolled AZ31 magnesium alloy sheet impacted under high strain rates, the as-received sheet was precompressed along the rolling direction(RD) to the true strain of 4% for inducing ■ tensile twins.The as-received and precompressed rolled AZ31 magnesium alloy sheets were impacted along the normal direction(ND) using a split Hopkinson pressure bar experiment apparatus at strain rates of 700,1000, 1300, and 1600 s;. Microstructural characteristics of the as-received, precompressed, and impacted specimens were analyzed and compared by an electron backscatter diffraction technology. The results show that in the precompressed specimen, the density of the basal texture was weakened and a new twin texture with the c-axis paralled to RD was formed. The average grain size of the precompressed specimen decreased visibly as a result of the parent grains being subdivided by tensile twin boundaries.The dominant deformation mechanism of the precompressed rolled AZ31 magnesium alloy impacted along ND is detwinning. With increasing the strain rate, the initial basal texture recovered, the average grain size increased, and the average twin thickness decreased. Compared with the precompressed specimen, the as-received specimen impacted along ND exhibited higher strength and lower formability.The precompressed specimen demonstrated greater strain rate sensitivity during plastic deformation.

关 键 词：AZ31镁合金 预压缩 高速冲击 退孪生 

分 类 号：TG146.2[一般工业技术—材料科学与工程]