High-Speed Superplastic Forging of High-Strength Light Alloys

Al-Cu-Mg和Al-Cu-Mg-Zn系合金采用机械合金化工艺制备。研究了机械合金化、压制和挤压工艺条件对材料超塑性行为和显微组织的影响。镦粗和长钉锻造是由液压机（低速）和机械压力机（高速）进行的。当机械合金化时间延长到一定程度时，晶粒尺寸不受机械合金化时间的影响，但存在一个最适合超塑延伸的机械合金化时间。随着挤压温度的降低，晶粒尺寸逐渐细化，经热处理和拉伸试验后，晶粒尺寸稳定。机械合金化材料的超塑延伸率随晶粒尺寸的减小而增大。该材料室温抗拉强度高，在机械压力机的高速下表现出超塑性延伸，适合于实际应用。用有限元分析方法探讨了高速超塑性变形的机理。这些材料在高速机械压力机上的锻造极限很高。

Al-Cu-Mg and Al-Cu-Mg-Zn alloys are made by mechanical alloying process. The influence of the condition of mechanical alloying, compaction and extrusion on the superplastic behavior and microstructure of the material are investigated. Upset and spike forging are conducted by a hydraulic press (low speed) and mechanical press (high speed). The grain size isn't affected by mechanical alloying time when mechanical alloying time becomes long to some extent but there is the most suitable mechanical alloying time for superplastic elongation. The grain size becomes fine according to decrease of extrusion temperature and the fine grain is stable after the heat treatment and tensile test are carried out. The superplastic elongation of mechanically alloyed material becomes large according to the decrease of grain size. The material developed is suitable in the actual use because its tensile strength at room temperature is very high and it shows superplastic elongation in as high speed as mechanical press. The mechanism of high speed superplastic deformation is discussed by using finite element analysis. Forging limit of these materials is very high when high speed mechanical press is used.