Cyclic Deformation and Damage Mechanisms in additive manufactured Ti-6Al-4V with Graded Microstructures

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Additive manufacturing (AM), also called 3D printing, has been widely recognised to be capable of offering a range of logistical, economic and technical advantages when compared with conventional manufacturing processes. For example, AM has opened up new business opportunities for the aerospace sector because of its reduced time-to-market and higher buy-to-fly ratio, in particular for titanium alloys. However, the widespread adoption of AM by industries for the production of metallic engineering parts/components remains a challenge. Lack of knowledge about the reliability of AM-built materials and associated concerns about engineering structural integrity has been identified as one of the hurdles to successfully commercialise this promising manufacturing process.Ti-6Al-4V is the most prevalent titanium alloy and is widely used in aerospace applications. Rolls-Royce PLC at Derby has applied AM technologies to repair aero-engine BLISKS (Bladed-Disks) and GE Aviation in the USA has developed AM-built fuel nozzles for the LEAP aero-engines. With AM moving into the production of more heavily loaded end-use components, particularly within the aerospace sector, improved understanding of the mechanical behaviour of AM parts/components under cyclic (fatigue) loading is essential. This requires the development of a mechanistic based lifetime assessment procedure for safety-critical engineering systems that contain AM-built parts/components.By engaging actively with both the UK's world-renowned AM manufacturing technology centre (MTC) and an end-user (Rolls-Royce PLC), this project will develop an experimentally-validated microstructure-based model that can be adopted when undertaking a lifetime prediction against fatigue crack initiation in AM-built Ti-6Al-4V.