Page 16 - CIM-Laser Annual Report 2014-2015

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EPSRC Centre for Innovative Manufacturing in Laser-Based Production Processes
The centre has a cohort of talented and enthusiastic researchers, this year they have been encouraged to develop and lead their own 4-6 month projects .
LASER TEXTURING OF STEEL TO IMPROVE LASER WELDING PERFORMANCE
One of the challenges in the automotive industry is to reduce the carbon emission of manufactured vehicles . This can be done by incorporating lightweight metallic alloys (e .g . aluminium alloys) with more generic automotive modulus (often made of uncoated mild steel) in order to reduce the total mass of a vehicle . Joining these two dissimilar metals together is a
difficult task because chemical reactions between aluminium alloy and uncoated low carbon steel lead to the formation of intermetallic compounds at the metals interface during a welding process and thus the mechanical properties of the welds are deteriorated .
This project aims to investigate a nanosecond laser texturing process for improving the laser spot welding performance of two dissimilar metals, i .e . aluminium alloy to uncoated low carbon steel, which are used in the automotive industry, in order to reduce the total mass of a vehicle .
MEET THE TEAM
Researchers: Dr Krysitan Wlodarczyk, Dr Sonia Meco Martins & Dr Goncalo Rodrigues Pardal
How is the project developing? Any exciting results so far?
The project is at its final stages and showing encouraging results . By using a nanosecond pulsed laser to texture the steel surface it is possible to
increase the tensile shear load of dissimilar metal spot welded joints between Al and steel by about 25%, compared with non-textured samples joined in the same conditions .
What is the main benefit of access to seedcorn funding?
Seedcorn projects allow researchers to start their own projects with their own ideas, giving us the freedom to carve our own niche in the centre . The funding allows us to develop more speculative ideas and generate initial results that can then be developed into larger projects with our industry partners . This particular seedcorn project between Heriot-Watt
and Cranfield has further developed researcher links inside the Centre .
What are the next steps for this research?
We will be developing this seedcorn project into a standard CIM project, using the results to approach our industry partners for joint funding . The preliminary results obtained with the seedcorn project are the perfect tool to persuade companies to fund a bigger project with higher aims and a possible commercial application .
DIAGNOSTICS AND PROCESS IMPROVEMENT FOR ULTRAFAST PS LASER WELDING
Ultra-fast ps welding is in principle a simple procedure . Two materials are brought into close proximity and a laser is focused onto the interface . Absorption at the interface produces a plasma that, when cooled, forms the weld . In practice laser- material interactions and particularly the absorption of the radiation are complex; this leads to a process which is hard to predict and difficult to optimise . At present we are researching the capability of ps welding to bridge gaps in both similar and dissimilar materials . Direct observation of this bridging behaviour would lead to a better understanding
of the process and allow for the welding of more industrially relevant components .
This project aims to create a portable imaging system to allow non-portable breadboard and brass board lasers and processing systems to be tested across the centre .
Researcher Seedcorn Projects