Friction Joining - Low Energy Manufacturing for Hybrid Structures in Fuel Efficient Transport Applications

Lead Research Organisation: University of Manchester
Department Name: Materials

Abstract

There are clear drivers in the transport industry towards lower fuel consumption and CO2 emissions through the introduction of designs involving combinations of different material classes, such as steel, titanium, magnesium and aluminium alloys, metal sheet and castings, and laminates in more efficient hybrid structures. The future direction of the transport industry will thus undoubtedly be based on multi-material solutions. This shift in design philosophy is already past the embryonic stage, with the introduction of aluminium front end steel body shells (BMW 5 series) and the integration of aluminium sheet and magnesium high pressure die castings in aluminium car bodies (e.g. Jaguar XK).Such material combinations are currently joined by fasteners, which are expensive and inefficient, as they are very difficult to weld by conventional technologies like electrical resistance spot, MIG arc, and laser welding. New advanced solid state friction based welding techniques can potentially overcome many of the issues associated with joining dissimilar material combinations, as they lower the overall heat input and do not melt the materials. This greatly reduces the tendency for poor bond strengths, due to interfacial reaction and solidification cracking, as well as damage to thermally sensitive materials like laminates and aluminium alloys used in automotive bodies, which are designed to harden during paint baking. Friction joining techniques are also far more efficient, resulting in energy savings of > 90% relative to resistance spot and laser welding, are more robust processes, and can be readily used in combination with adhesive bonding.This project, in close collaboration with industry (e.g. Jaguar - Land Rover, Airbus, Corus, Meridian, Novelis, TWI, Sonobond) will investigate materials and process issues associated with optimising friction joining of hybrid, more mass efficient structures, focusing on; Friction Stir, Friction Stir Spot, and High Power Ultrasonic Spot welding. The work will be underpinned by novel approaches to developing models of these exciting new processes and detailed analysis and modelling of key material interactions, such as interfacial bonding / reaction and weld microstructure formation.

Publications

10 25 50

 
Description Systematic research was carried out on the targeted processes, of the material flow, defect formation, and bonding mechanisms, using advanced characterisation techniques like 3D micro-tomography. The results were compared to process models developed in parallel by Cambridge University. The work gave a new insight into the welding processes and revealed that, when applied to dissimilar materials, they did not behave as had been previously expected, which led to poorer performance and delayed weld formation. In particular, the longer time required to form optimum joint strengths caused more extensive intermetallic reaction than anticipated and gave too long a process cycle for industrial application.
Reaction was found to occur much faster in welding than in static heat treatment, due to the high strain-rate deformation. In the case of Zn coated steels to Al, and Mg-Al welds, the presence of low melting point reactions led to liquation at the welding interface, despite the 'solid state' nature of the welding processes.
Solutions were explored to produce more rapid welds and control the level of interfacial reaction. The results have been disseminated in over 40 publications and attracted interest from additional automotive companies, including Nissan, Honda, GM and Chrysler.
Exploitation Route The findings have been passed on to industrial collaborators and have been developed fra further within a Programme grant - LATEST2
Sectors Aerospace, Defence and Marine,Manufacturing, including Industrial Biotechology,Transport

 
Description The results from the work have been presented at workshops with JLR and attracted visits from interest from additional automotive companies, including Nissan, Honda, GM and Chrysler, who have visited Manchester to discuss dissimilar joining. The work has thus influenced their thinking on adopting new dissimilar technologies.
Sector Aerospace, Defence and Marine,Manufacturing, including Industrial Biotechology,Transport
Impact Types Economic

 
Description EPSRC Pogramme Grant
Amount £5,762,121 (GBP)
Funding ID EP/H020047/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 07/2010 
End 01/2016
 
Description Friction Joining - Low Energy Manufacturing for Hybrid Structures in Fuel Efficient Transport Applications (JLR) 
Organisation Jaguar Land Rover
Country United Kingdom 
Sector Private 
PI Contribution Research into dissimilar, friciton and ultrasonic welding
Collaborator Contribution Funded an EngD student on USW and sponsored a PhD student In-kind support in developing a USW manufacturing cell
Impact The work has influenced their thinking on adopting new welding technologies for light alloys.
Start Year 2009
 
Description Friction Joining - Low Energy Manufacturing for Hybrid Structures in Fuel Efficient Transport Applications (Novelis) 
Organisation Novelis Global Research and Technology Center
Country United States 
Sector Private 
PI Contribution Supply of materials and interest in outcomes for automotive manufacturing
Collaborator Contribution Supply of al-alloys to project and technical advice
Impact The work has thus influenced their thinking on joining aluminium intensive multi-material strucutres in automotive
Start Year 2009