多道次大压下轧制对AZ31镁合金薄板组织和性能的影响

Influence of multi-pass rolling with large reduction on microstructure and properties of AZ31 magnesium alloy sheets

对AZ31镁合金薄板分别进行多道次小压下及大压下轧制,平均道次压下率分别为14.5%和46%,研究两种轧制方式下AZ31镁合金的组织演变与力学性能。结果表明,小压下轧制AZ31镁合金板材表面氧化严重,组织逐渐均匀变细小,力学性能逐渐升高;大压下轧制方式AZ31镁合金板材表面氧化程度小,但是随着道次增加,表面出现薄屑,组织逐渐均匀细小,而剪切带越来越明显,力学性能逐渐下降。大压下轧制的板材组织中出现剪切带能够明显降低其力学性能。大压下轧制过程中,动态再结晶一直发挥重要作用,而小压下轧制初期主要变形机制为滑移,随着道次增加动态再结晶逐渐参与协调变形。

The AZ31 magnesium alloy sheets were subjected to continuous multi-pass rolling with small and large reductions respectively,of which the average reduction per pass was14. 5% and 46% respectively. The microstructure and mechanical properties of AZ31 magnesium alloy in both rolling modes have been investigated and compared. The results show that the AZ31 magnesium alloy sheets experienced small reduction rolling are severely oxidized at surfaces,which are barely oxidized during large reduction rolling. With rolling passes increased,the microstructure becomes gradually homogeneous and refined and the mechanical properties come to be decreased. The microstructure of large reduction rolling sheets are not only homogeneous and refined,but characterized by shear band,which produces great influence on the weakening of the sheets. During large reduction rolling,dynamic recrystallization plays an important role,but the main deformation mechanism is slip at the early stage of small reduction rolling,and with the passes being increased,dynamic recrystallization begins to accommodate deformation gradually.