Development of Friction Stir Welding of Titanium Alloys for Spacecraft Propellant Tanks

Ti-6Al-4V titanium is the current baseline alloy for rocket/spacecraft propellant tanks. These tanks are usually manufactured from forged feedstock and then welded using a combination of TIG and Electron Beam (EB) welding.  Although the current manufacturing route produces tanks with a reliable performance, tank manufacturing is still one of the most costly items in the rocket/spacecraft motor system. The high cost is due primarily to the extensive amount of machining which is required, coupled with the discard of a high quantity of material lost as chips.  Furthermore, the evolution of larger motor systems is demanding even larger tanks, which threatens to become prohibitively costly if manufactured by traditional methods.

In this collaborative project between TWI, ESA and Airbus Defence & Space UK, alternative methods for manufacturing of titanium propellant tanks are being explored including the combination of FSW with forging, casting and spin forming. The project focuses on the development, characterisation and validation of the FSW process and tooling system starting from sheets up to formed shells. Finally the validated processes will be upscaled and full size tanks will be manufactured. 

This presentation will discuss the first year of work in this 2 year project, and the methodologies that will be used to meet the project deliverables.