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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 Section Manager – Friction and Forge Processes

Steve joined TWI’s Friction and Forge Processes (FFP) technical team in 2013. His connection with TWI came through TWI’s industrial support for his PhD, which focussed on developing the friction stir welding of steel. In the role of Senior Project Leader, Steve created and delivered a broad range of projects related to friction welding. Activities range 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 processes. He also has experience in establishing quality control and assurance in the production of friction-welded defence hardware.

In 2016 Steve took the position of FFP Section Manger, making him responsible for the section’s strategic and technical direction. This role has led Steve to become highly aware of both the needs of industry and advanced manufacturing technologies. The combination of Steve’s enthusiasm in challenging convention and the backing of a highly experienced team has permitted FFP to remain principal innovators of friction-based manufacturing technologies.