A series of experiments were performed by use of various forming paths during superplastic forming of an el-Li based alloy. A fully recrystallized Al-Li-Cu-Mg-Zr alloy could be formed superplastically using paths of either a constant or a variable strain rate. The distribution of thickness along-the formed sheet was confirmed by the results as being not much sensitive to the forming paths. The uniformity of the formed part affected the microstructural characteristics; the grain size was larger in regions at which the plastic deformation was larger, an effect was believed due to strain-induced grain growth. Static growth of grain showed little effect on an Al-Li based alloy during superplastic forming. The strain-induced grain growth influenced the distribution of grain size, resulting in cavitation occurring in the regions of large grain size. A two-step variable forming path could reduce cavitation in the formed part.
