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采用金相分析、拉伸试验、SEM分析等方法测试和分析了AZ91D镁合金在铸态、锻压态及锻后+人工时效处理态下的金相显微组织和力学性能。研究表明:锻前均匀化退火能使沿晶界分布的网状β-Mg17Al12相全部溶入基体α-Mg中;等温模锻成形过程中,合金发生了明显的动态再结晶,形成细小的再结晶等轴晶粒组织,合金力学性能相对铸态有大幅提升;锻后人工时效,合金中重新弥散析出β-Mg17Al12相,合金强度提升,而塑性有所下降。3种状态下合金断口形貌均呈现出混合断裂的特征。
The microstructure and mechanical properties of AZ91D magnesium alloy after as-cast, forging and forging + artificial aging treatment were tested and analyzed by metallographic analysis, tensile test and SEM analysis. The results show that the uniform β-Mg17Al12 phase distributed along the grain boundary can be completely dissolved into the α-Mg matrix during forging homogenization. During the isothermal forging process, the alloy undergoes significant dynamic recrystallization to form a fine Crystalline equiaxed grain structure, the mechanical properties of the alloy has a significant increase relative to the as-cast; forged artificial aging, the alloy again precipitated β-Mg17Al12 phase alloy strength increased, while the plastic decreased. The fracture morphology of the alloy shows the characteristics of mixed fracture in all three states.