Corrosion study of WAAM printed and repaired stainless steel parts for aerospace applications - Meron Desalegn Tuemay

The EU has put forward the European Green Deal to decrease the costs associated to mass-production industries. To reduce the cost and ecological impact of metal production and processing, innovative technologies are emerging. By Additive Manufacturing (AM), a metal is built layer by layer into a near net shape product, reducing: (1) postprocessing needs, (2) the use of production chemicals, lubricants and water (highly valuable resource of our planet!), (3) waste of metal resources, and (4) total processing energy. Also for worn or otherwise damaged metal parts, instead of completely replacing them and wasting valuable metal resources, repair by AM is possible for reuse and lifetime extension. In addition, for efficient use of resources and time, hybrid manufacturing is possible, where relatively simple parts of a product can be manufactured using well-established/cheap/fast conventional methods (casting, forging, extrusion…) and add-ons with more complex geometries can be fabricated by AM on the conventional part. However, during metal AM, interfaces are formed between the deposited metal and the receiving substrate, and these regions have uncontrolled and unknown features, e.g. precipitations, compositional gradients, grain orientation & size variations, heat-affected zones etc., that make the interfaces susceptible to corrosion. In this PhD project the main objective is to fundamentally study the relationship between the formed interfaces in AM production and repair approaches and the resulting atmospheric corrosion behavior, in relation to the Wire Arc Additive Manufacturing printing conditions and additional thermal post-processing. The research will be done on a stainless steel alloy, used for an aerospace re-entry grid fin plate. The methodology that will be employed is a multidisciplinary approach based on combined experimental and modelling methods, joining the expertise of the home and partner institutes VUB and NOVA, with industrial interest and research support.