Fabrication of Sandwich Structure with Superplastic Forming Process from Diffusion Bonded Ti-6Al-4V Sheets

It is well known that the utilization of superplastic characteristics in manufacturing process makes many of aerospace components lighter and stiffer. The weight saving is vitally important especially for aerospace application and even more weight saving is possible when the superplastic forming is carried out with diffusion bonding. In this study, the lightweight sandwich structure was fabricated with superplastic forming(SPF) process from diffusion bonded(DB) Ti-6Al-4V sheets. The solid state diffusion bonding process was conducted in non-vacuum environment under a pressure of 4MPa for 60 minutes at 875°C and the superplastic forming process was followed for another 40 minutes. Good solid state bonding interface have been observed in microstructure observation and the sandwich structure was successfully manufactured. It is important to note that the forming conditions of present study are more practical for application than the previously published conditions, which require vacuum environment, higher temperature and/or pressure.