均匀化退火工艺对铸态AZ80镁合金组织与性能的影响

Influence of Homogenizing Annealing Process on Microstructure and Mechanical Properties of As-cast AZ80 Magnesium Alloy

研究了均匀化退火工艺对AZ80镁合金组织和性能的影响,用扫描电镜对铸态和均匀化退火后试样室温拉伸断口进行了分析。结果表明,均匀化退火能有效消除枝晶偏析、改善材料的组织和力学性能。确定390℃×16 h均匀化退火为合金的最佳处理工艺。冷速的快慢造成析出沉淀相形貌和数量差异,引起合金力学性能不同。冷速越大,硬度和强度越高,而伸长率越小。铸态试样室温拉伸断口为准解理断裂加少量剪切断裂,经均匀化处理后断裂方式由沿晶断裂转变为穿晶断裂。

The effects of homogenizing annealing process on the microstructures and properties of AZ80 magnesium alloy were investigated and the fracture of specimens before and after homogenizing annealing was also analysized by SEM. The results show that after homogenizing annealing, dendritic segregation is almost eliminated and the microstructures and properties of alloy are improved. The optimal homogenizing annealing process is at 390 ℃ for 16 h. The precipitating behavior,which depends on the cooling rate, has an effect on the mechanical properties of alloys. The higher the cooling rate, the higher the hardness and strength while the lower the elongation. Fractography demonstrates that the as-cast alloys＇ tensile fracture consist of quasi-cleavage fracture mixed a little shear fracture and the alloys＇ tensile fracture mode after homogenizing is changed from intergranular fracture to transgranular fracture.