Processing, Microstructure and Hydrogen embrittlement of 3D printed Inconel718

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Additive manufacturing (AM), also known as 3D printing, is expected to revolutionise the way of designing, supplying and making materials, holding great potential for automotive, energy, medical and aerospace applications. Amongst all AM, powder bed fusion is the most effective method to fabricate complex metallic components with high accuracy.Inconel718 is one of the most widely used nickel-based alloys thanks to its good weldability, excellent resistance to fatigue, to hot corrosion and to wear and high strength, making it an excellent candidate for high-temperature applications including in gas and oil.Although the microstructure and mechanical behaviour of Inconel 718 have been extensively studied, there is still significant lack of understanding regarding the relationship between AM process parameters, microstructure and performance - in particular the hydrogen embrittlement. Therefore, this project will use the laser powder bed fusion to fabricate Inconel718 with various print parameters. Subsequently, detailed studies will be carried to examine the microstructure evolution of the alloy from single to multiple tracks of deposition and in subsequent heat treatments. Mechanical tests will be done on both as-printed and heat-treated conditions with and without charged Hydrogen to study the susceptibility of the alloy to hydrogen embrittlement.Tasks will be carried out in this project:- Fabrication: Relating print parameters (i.e laser intensity, exposure time, laser spot distance, hatch spacing, layer thickness and scanning strategy) to consolidation and solidification microstructure.- Uniaxial tension testing at room and elevated temperatures will be carried out on the printed alloy with and without the charging of Hydrogen to study the hydrogen embrittlement. - Microstructure characterisation: Microstructure morphology, crystal phases, crystallographic orientations and chemical distribution of as-printed and deformed samples will be characterised by optical and scanning/transmission electron microscopy (including EDX) and X-ray diffraction.