Sheffield Hallam University is pleased to announce that, in partnership with TWI (formerly The Welding Institute) and Ionbond UK Ltd, it has won a collaborative research project supported by Innovate UK to develop coatings for Friction Stir Welding (FSW) tools.

The project will investigate the potential to increase the performance of FSW tools by using advanced coatings deposited by Ionbond's PVD, CVD and PACVD processes. In particular, it will be testing coatings deposited by the latest variant of PVD - HIPIMS (High Power Impulse Magnetron Sputtering), which Sheffield Hallam University has developed through a number of EPSRC and European Framework projects for use in commercial applications. Our partner, Ionbond UK, is the market leader in PVD coatings and has also been evaluating HIPIMS technology for use in commercial applications. 

Friction Stir Welding (FSW), which was invented by TWI, is an innovative joining process using a rotating, non-consumable tool, which is traversed along the interface of two work-pieces. The process typically provides enhanced weld quality, strength and durability together with reduced energy consumption and environmental impact when compared to conventional fusion welding processes.

However, FSW tooling works in an extremely demanding environment - high temperature (>700°C), high abrasion and exposure to the reactive effects of freshly exposed metal surfaces - this has limited its commercial application to low melting point alloys, principally aluminium. 

Through the application of advanced coatings, we hope to enable the welding of 'high-temperature' materials, such as steel and titanium for high-value industries (e.g. Aerospace & Transport) as well as improving the surface quality of welds in aluminium and other alloys.

*Images are courtesy of TWI Ltd, UK

FSW of high-temperature alloys    Surface defects during high speed SSFSW