Elevated Temperature Forming of Titanium Aircraft Hardware

Abstract

Titanium is difficult to fabricate into complex aircraft configurations. There is several elevated temperature forming techniques that are available to produce titanium components for aircraft, two of which will be discussed here: Superplastic Forming (SPF) and hot forming. SPF is used when complex shapes are required, for example, tight radii, and uses a tool that contains the required configuration and seals around the periphery so inert gas pressure can be used to form the material. Since SPF is a process where the material is stretched, the part is not a uniform thickness when completed. A variation of the process combines SPF with diffusion bonding (SPF/DB) of two or more pieces of titanium together to produce integrally stiffened structure containing very few fasteners. The hot forming process uses matched metal tools, offset by the thickness of the starting material, are used to form the part contour at elevated temperature. The required part geometry usually contains no sharp features that have to be formed. Since the material is free to move as the die is closed, the part is fairly uniform in thickness when completed.