FE simulation and experimental considerations on TI alloy superplastic forming for aerospace applications

Titanium and its alloys have rapidly become a strategic material in aerospace industry due, for example, to high strength vs. weight ratio, excellent mechanical proprieties, corrosion resistance and galvanic compatibility with fiber reinforced composite materials. A big problem that has to be considered is, however, the higher cost of components as compared to other alloys. In fact, the market price of the base metal has to be added to manufacturing ones. To reduce production costs, Titanium net shape technologies have been continuously developed. Superplastic forming (SPF) technology can be considered in this frame. Through the SPF some alloys can be slowly formed well beyond their normal limitations at elevated temperatures, allowing very deep forming sequences. In this study, the SPF process to produce aircraft parts was investigated. The well-known Titanium alloy Ti6Al4V was chosen as workpiece material. The investigation was carried out by numerical analysis to check the predicting capability of these simulation tools. In detail, FE analyses were developed using two different codes, namely Marc and Ls-Dyna. The aim was the optimization of pressure trend to obtain the desired shape with a reasonable accuracy and without material breaking. Finally, some considerations on the experimental manufacturing of the components are reported.