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Friction stir welding for low-cost titanium propellant tanks

Published on 28 July 2017

TWI has been working with astrospace contractor Airbus Defence and Space to satisfy a European Space Agency (ESA) request to investigate cost-effective manufacturing methods for titanium propellant tanks.

The project investigated the feasibility of using stationary shoulder friction stir welding (SSFSW) techniques for the cylindrical welding of titanium alloys suitable for launch vehicle propellant tanks. The investigations sought to reduce lead times and costs by developing and validating a system required to weld titanium alloys and also to raise the Technology Readiness Level (TRL) of SSFSW of titanium alloys to prototype demonstrator (TRL6).

Current manufacturing methods for titanium propellant tanks suffer from extremely high cost and long manufacturing lead times. Material wastage from complicated forging, machining, and forming techniques coupled with electron beam (EB) welding makes propellant tanks one of the most expensive hardware items on a satellite launch programme.  While friction stir welding (FSW) is capable of welding high strength high temperature materials such as steel and nickel alloys, by using the modified version of FSW, Stationary Shoulder Friction Stir Welding (SSFSW), titanium can also be welded successfully.

The TWI team conducted an extensive review of material and manufacturing processes, with forged and cast titanium both offering the mechanical property requirement. In August 2016 TWI successfully performed the world’s first full circumferential SSFSW of two 420mm cast titanium cylinders. The test pieces were then subjected to full NDT evaluation and mechanical assessment to confirm joint quality and properties.

In winter 2016, TWI fabricated and delivered the first one of four SSFSW cast titanium prototype demonstrator (TRL6) propellant tanks to the European Space Agency, with a delighted response from ESA.

The achievement and success of the ESA-TWI-Airbus team was recognised, in March 2017, when they were awarded the Raiser 2017 Award for Friction Welding Innovation.

For more information, please email

Avatar Dr Steve Dodds Nuclear Power Sector Manager

Steve joined TWI in the Friction and Forge Processes (FFP) team in 2013 following his PhD, which focussed on developing the friction stir welding of steel. As a Senior Project Leader and later as Section Manager, Steve delivered a broad range of projects, ranging from pre-competitive research through to manufacturing support and technology transfer. Steve has a particular interest in the friction welding of dissimilar metals/materials and redesigning components to access the benefits of friction joining.

In 2021 Steve became the Nuclear Power Sector Manager at TWI, responsible for all aspects of Nuclear and Big Science interactions with TWI Members and the wider global community.