本文研究了多向锻造工艺对镁合金组织和性能的影响。实验表明：通过多向锻造大塑性变形工艺成功制备出晶粒度在1～2µm镁合金锻坯，材料组织均匀，机械性能得到很大提高。形变诱导晶粒细化是主要的晶粒细化机制，同时也是一种非形核长大过程。与单轴成形工艺相比，多向锻造大变形下材料内部易产生交错变形带，有利于组织细化。材料晶粒细化过程存在一临界应变量 εc（ 2<εc<2.4），当实际变形量εx超过临界变形量εc时，材料基本为动态再结晶细晶组织，进一步细化变得困难。铸态试样室温拉伸断口为准解理断裂加少量剪切断裂，锻后材料断口出现大量细小韧窝，随应变量的增加，细小韧窝数目增多，分布趋向均匀，材料延性相对较大。
The effect of multiple forging process on the microstructure and properties of magnesium alloy was investigated in the present paper. The results show that using the method of multiple forging, a homogeneous microstructure with ultrafine grains（1～2µm）can be attained and mechanical properties of alloy can be significantly improved. The dynamic formation of new grains during the deformation can result from a series of strain-induced continuous reactions that are essentially similar to continuous dynamic recrystallization and the intercrossing deformation bands developed in the coarse grains are beneficial for grain refinement. The microstructure with fine dynamic recrystallized grains can be attained when the applied total strain εx exceeds the critical strain εc which is in the rage of 2～2.4. After that, it is difficult to get more grain refinement further. Fractography demonstrates that the as-cast alloys’ tensile fracture consists of quasi-cleavage fracture mixed a little shear fracture and the microstructure morphologies of the alloy after forging are ductile dimple. At the same time, the dimples increase and exist more homogeneously with the increase of strain.
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