连续变断面循环挤压AZ31镁合金的微观组织与力学性能

Microstructure and Mechanical Properties of AZ31 Magnesium Alloy Produced by Continuous Variable Cross-section Recycled Extrusion

采用连续变断面循环挤压技术(CVCE)对AZ31镁合金进行循环挤压。采用光学显微镜、电子拉伸机等设备,分析变形前及不同循环道次后AZ31镁合金的微观组织和力学性能。结果表明:AZ31镁合金经10循环CVCE后,平均晶粒尺寸由变形前25.3μm有效细化到5.5μm;伸长率提高到34.3%,抗拉强度下降到200MPa。由于晶粒细化效应,导致α相主要变形机制由1循环的孪生变为随后道次的位错滑移。抗拉强度的降低与挤压后(0001)晶面取向分布的分散性有关;伸长率的增大与晶粒细化和滑移面的激活有关。

AZ31 magnesium alloy was circularly pressed by continuous variable cross-section recycled extrusion （CVCE） technology. Microstructure and mechanical properties of AZ31 magnesium alloy before and after deformation were observed and analyzed by optical microscopy, electronic drawframe and so on. The results indicate that after ten cycles of CVCE, the average grain size of AZ31 magnesium alloy is refined from 25.3btm to 5.5μm elongation of the alloy increases to 34.3% and tensile strength decreases to 200MPa. Grain refining effect is responsible for the deformation mechanism of a phase from twining in the first pass to the dislocation glide in the following passes. The decrease of tensile strength is related to the dispersive orientation of （0001） crystal face after pressing and the increase of elongation is attributed to the grain refinement and the activation of sliding planes.