异步轧制AZ31镁合金板材的孪晶组织及织构

Twins and texture of AZ31 magnesium alloy sheet by asynchronous rolling

采用异步轧制（AR）工艺和同步轧制（NR）工艺制备了AZ31镁合金板材，分析了AZ31镁合金板材的组织性能和力学性能，研究了轧制过程中孪晶组织和织构的演变规律，以及异步轧制工艺参数对镁合金板材组织、织构和力学性能的影响。结果表明，在压下量为3％～15％的范围内，异步轧制与同步轧制板材在晶粒尺寸以及均匀性上有相似的变化趋势。在变形初期，随压下量的增加，孪晶数量不断增加，孪晶使异步轧制与同步轧制板材中晶粒取向都发生偏转，即C轴趋向于垂直于法向（ND），从而使初始挤压板材的丝织构强度减弱；当压下量达到24％时孪晶大量减少或消失。在压下量为3％～24％的范围内，同步轧制对板材力学性能的影响并不明显，峰值应变呈交替性变化，异步轧制板材在压下量达到24％时，表现出了良好的塑性变形能力，抗拉强度达到309MPa，峰值应变达到16．3％。

Asynchronous rolling（AR） and normal rolling（NR） technology were used to manufacture AZ31 magnesium alloy sheet. The texture and mechanical properties of the rolled AZ31 magnesium alloy sheet were analyzed. The evolvement mechanism of twins and texture for AZ31 magnesium alloy was studied. The influence of technology parameters on microstructure and texture and mechanical properties of the alloy was examined. The results show that when the total reduction ratio is in the range of 3% - 15% , the grain size and uniformity exhibit similar changing trend for AR and NR technology. During the initial stage of rolling, with the increasing of reduction ratio,the number of twins raises, which makes the grain orientation changing in rolled sheets. Namely, axis C of grains inclines towards the normal direction （ND） , which weakenes the silk texture of the extruded sheet. When the total reduction ratio reaches 24% , twins decrease significantly and even disappear. When the total reduction ratio is in the range of 3% - 24% , the influence on mechanical properties is not obvious by normal rolling. When total reduction ratio reaches about 24% , asynchronous rolled sheets present good plastic performance, and the tensile strength is 309 MPa, and the peak strain is 16.3%.