( 1. 北京有色金属研究总院 北京 100088;
2. Brunel University, Uxbridge, Middle Sex U138 3PH, UK;
3. 北京科技大学 新金属材料国家重点实验室， 北京 100083)
摘 要: 采用双螺旋流变铸造工艺制备了镁合金AZ31B的棒坯， 利用Gleeble-3000型热/力模拟机研究了流变铸造和普通连铸棒坯在变形温度为250~400 ℃， 变形速率为0.001~5 s-1， 最大变形量为60%时的热压缩变形行为。 分析了材料流变应力与变形量、 变形温度和应变速率之间的关系， 比较了两种不同铸造工艺对热塑性变形行为的影响。 结果表明： 流变铸造坯料在变形过程中的形变均匀性明显优于普通铸造的， 因此不需预处理即可直接进行塑性成型； 350 ℃以上热变形流变铸造坯料的变形抗力明显小于普通铸造坯料的； 流变铸造使AZ31B合金的塑性加工性能得到改善； 产生这种差别的主要原因是普通铸造坯料组织为粗大树枝晶， 而流变铸造坯料组织为细小等轴晶。
关键字: 镁合金； 流变铸造； 热/力模拟
（ 1. General Research Institute for Nonferrous Metals, Beijing 100088, China;
2. Brunel University, Uxbridge, Middle Sex U138 3PH, UK;
3. State Key Laboratory for Advanced Metals and Materials,
University of Science and Technology Beijing, Beijing 100083, China）
Abstract: The billet of magnesium alloy AZ31B was prepared by the method of twin-screw rheo-casting and normal casting. The hot compression of these two kinds of samples at 250-400 ℃ was performed on Gleeble-3000 hot simulator with the strain rates of 0.001-5 s-1, and the maximum deformation of 60%. The relationship among the stress, deformation temperature and strain rate were analyzed and compared. The results show that the deformation of rheo-casting billet is more uniform than that of the normal casting in the compression process, so the rheo-cast billet can be hot deformed directly. The maximum stress of rheo-casting is less than that of the normal casting at above 350 ℃, which means that the billet made by rheo-casting can be deformed easier than normal casting. The reason of the difference is that the microstructure of rheo-casting is composed of uniform, tiny and equal-axial grains; while the microstructure of normal casting is coarse dendrite.
Key words: magnesium alloy; rheo-casting; hot compressive deformation simulation
