Research to improve welding and 3D printing processes for manufacturing industries

^{Image copyright belongs to Aucott, L., Dong, H.B., Mirihanage, W.U., Atwood, R.C., Kidess, A., Gao, S., Wen, S.W., Marsden, J.A., Feng, S., Tong, M., Connolley, T., Drakopoulos, M., Kleijn, C.R., Richardson, I.M, , Browne, D.J., Mathiesen, R.H., Atkinson, H.V.}

New research, led by the University of Leicester, will optimise the welding and additive manufacturing process Arc welding and additive manufacturing are hugely important for creating large metal components relatively inexpensively and quickly.

New research led by Professor Hongbiao Dong from the University of Leicester’s Department of Engineering has shown how to optimise this process to improve efficiency and cost. The research, which was a collaboration between the University of Leicester, Delft University of Technology, Diamond Light Source, University College Dublin and TATA Steel Research UK was recently published in Nature Communications.

It explores the internal flow behaviour in additive manufacturing of metals and arc welding – the most widely used welding process in modern manufacturing.

The work focused on examining the melt pools that are created during the welding process.

To do this, the team inserted small tungsten and tantalum particles into the melt pool. Due to their high melting points, the particles remained solid in the melt pool long enough for them to be tracked using intense beams of X-rays.

The X-rays were generated using the synchrotron particle accelerator at Diamond Light Source, which is the UK’s National facility for synchrotron light. Beamline I12 was selected for this research due to its specialised high energy, high-speed imaging capability at thousands of frames per second.
Using Beamline I12, the researchers were able to create high-speed movies showing how surface tension affects the shape of the welding melt pool and its associated speed and patterns of flow. The results showed, for the first time, that the melt flow behaviour is similar to that previously only seen via computer simulations.

The results revealed that arc welding can be optimised by controlling the flow of the melt pool and changing the associated active elements on the surface.

Professor Dong said: “Understanding what happens to the liquid in melt pools during welding and metal-based additive manufacturing remains a challenge. The findings will help us design and optimise the welding and additive manufacturing processes to make components with improved properties at a reduced cost.

Welding is the most economical and effective way to join metals permanently, and is a vital component of our manufacturing economy.”

Dr Thomas Connolley, Principal Beamline Scientist for I12 at Diamond Light Source commented: “The I12 team was closely involved in the experiment. The beamline was designed with these challenging in-situ experiments in mind and I am very happy that we have helped advance understanding of additive manufacturing and welding, given their technological importance.”

It is estimated that over 50% of global domestic and engineering products contain welded joints. In Europe, the welding industry has traditionally supported a diverse set of companies across the shipbuilding, pipeline, automotive, aerospace, defence and construction sectors. Revenue from welding equipment and consumable markets reached €3.5 billion in Europe in 2017.

The UCD co-authors are Prof. David Browne and Dr Mingming Tong (now at NUI Galway) of the School of Mechanical and Materials Engineering. The European research collaboration was established during the project “MintWeld” (Modelling of Interface Evolution in Advanced Welding) which was funded by the European Commission under the FP7 programme for research. Prof. Browne’s Phase Transformation Research Group concentrates on alloy solidification, and he explains: “We started here at UCD studying alloy solidification in casting process, and then extended this to welding and joining processes within the MintWeld project. This involved investigations into both melting and subsequent solidification in multi-pass welding. This extended scope of our research is the subject matter of this Nature Communications paper . The multiple passes of melting and solidification are also relevant to 3D printing (a.k.a. Additive Manufacturing) in metals, and now my group is studying these phenomena as part of the new SFI Advanced Manufacturing Research Centre, based at UCD, known as I-Form . We are applying our findings on casting and welding to the 3D printing of alloys, which involves selective melting, by a laser or electron beam, of a bed of loose powders, layer by layer. We are adapting our computer modelling techniques to simulate the melting and subsequent evolution of grain and micro structure as the alloy solidifies, causing the powder particles to fuse together. Our industry partners are particularly interested in these investigations, as this resultant microstructure determines the properties of the printed parts.”

The results will help with the future designing and optimisation of the welding and additive manufacturing process, and will have an important and far-reaching impact.

ENDS

The paper can be found in Nature Communications.

About Diamond Light Source: www.diamond.ac.uk Diamond Light Source is the UK’s synchrotron science facility. Shaped like a huge ring, it works like a giant microscope, harnessing the power of electrons to produce bright light that scientists can use to study anything from fossils to jet engines to viruses and vaccines. Diamond speeds up electrons to near light speeds, producing a light 10 billion times brighter than the Sun, which is then directed off into 33 laboratories known as ‘beamlines’.

Each year thousands of scientists use the UK’s synchrotron and its integrated facilities (eBIC, ePSIC etc.), with 57% visiting and 43% accessing the facility remotely. Diamond’s state-of-the-art facilities and world-class people act as agents of change, addressing 21st century challenges such as disease, clean energy and food security. Diamond research supports new medicines, technologies and advances of all kinds. More than 7,000 papers have been published because of research conducted at the facility.

To find out more about the I12 beamline, or to discuss potential applications, please contact Principal Beamline Scientist Thomas Connolley: thomas.connolley@diamond.ac.uk