3D in-situ based methodology for optimizing the mechanical performance of selective laser melted aluminium alloys

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Additive Manufacturing (AM), also known as 3D printing, is a common term used to describe the technology in which three-dimensional (3D) objects are fabricated by successive layers of material. The UK has been at the forefront of global innovation in AM and has also set up applications for commercialisation of this technology. While AM has been commonly employed for producing prototypes and tooling for decades, UK manufacturing industry has more recently been making revolution by using this technology for end-use products in various key sectors due to its economic and technical benefits in comparison with traditional manufacturing techniques. Once the current barrier to adoption of AM (i.e., quality, uncertainty of the final component and expertise) has been addressed, it is expected that this new emerging time-efficient AM technology has obvious capability to considerably boost UK economic production.Selective laser melting (SLM) is one of the most promising metal AM methods where 3D components are fabricated by using a high-energy laser beam to fuse the pre-deposited metal powder. The use of SLM has been progressively increasing in a number of UK industrial sectors (i.e., aerospace, automotive, medical, oil & gas, marine and defence etc.) owing to its capability to produce near-net shape complex components from a CAD model and hence offering robust design flexibility without the constraints of conventional manufacturing methods that require a series of manufacturing processes, more material consumption, higher cost and energy. For manufacturing industry that targets to fabricate their products rapidly and access to wider purchaser markets, SLM appears to be an ideal route for their businesses if the inter-related relationships between process parameters and their ultimate effect on the structural integrity and performance has been established.SLM is prevalently used to build in a range of metallic materials including stainless steel, titanium, nickel and aluminium alloys. Unlike the other alloys, manufacturing aluminium alloys by SLM involves more complexities due to being their high reflectivity and thermal conductivity which contribute to stimulate porosity in manufactured parts. Hence, there is presently a lack of understanding about the effect of SLM process parameters on microstructure and material performance in aluminium alloys. Determining such unknown relationships are an essentially important engineering mission that presently represents a major barrier to widespread usage of SLM processed aluminium alloys.The overall aim of this First Grant proposal is to develop a robust methodology to optimize the manufacture of aluminium alloy components using selective laser melting. In achieving this, the combined use of X-ray microcomputed tomography with an in-situ microtensile testing stage (allowing observations of the 3D in-situ deformation) will be employed to investigate the impact of process parameters on porosity, material properties and failure behaviour. In addition, an experimentally based porous plasticity finite element model will be developed to understand the effect of void size and shape on deformation behaviour.