CAN DESIGN FOR NONISOTHERMAL PANCAKE FORGING OF GAMMA-TITANIUM ALUMINIDE ALLOYS

The design of cans to produce uniform, defect-free gamma titanium alum inide alloy pancakes via conventional, nonisothermal forging, was esta blished using finite element modeling (FEM) and laboratory validation trials. The specific problem addressed was ingot breakdown via pancake forging a process typically comprising a high reduction ratio (simila r to 6:1) and a moderately high deformation rate (similar to 1 s(-1)) to minimize the effects of die chilling. Can and process variables inv estigated in the FEM simulations included can end cap shape and thickn ess, ram speed, and preheat temperature. The FEM results demonstrated that there is an optimal end cap thickness and ram speed to obtain mod erately uniform flow between the can and titanium aluminide workpiece. These results were validated through trials on the near-gamma titaniu m aluminide alloy Ti-45.5Al-2Cr-2Nb forged in AlSl type 304 stainless steel cans.