Advances in Fabricating Superplastically Formed and Diffusion Bonded Components for Aerospace Structures

摘要

Superplastic forming and diffusion bonding (SPF/DB) production hardware is being fabricated today for aerospace applications. Metal tooling is being used to bring the titanium sheets into contact so diffusion bonding can occur. However, due to material sheet and tooling tolerances, good bond quality is difficult to achieve over large areas. A better method for achieving DB is to use "stop-off inside sealed sheets of titanium, which constitutes a pack, and then the pack is bonded using external gas pressure. A good method for heating the pack for this process is to use induction heating. Components using "stop-off that were diffusion bonded first and then superplastically formed have shown much better bond quality than components that were produced using matched metal tooling. This type of tooling has been successful at bonding small areas as long as the exerted pressure is concentrated on the area where bonding is required. Finite element modeling is providing weight effect solutions for titanium SPF/DB aerospace structures.