Title: Functionally-graded materials and complex alloy systems through wire-arc additive manufacturing

Abstract

Wire-arc additive manufacturing (WAAM) is receiving increasing attention due to advantages in terms of component costs, deposition rate and buy-to-fly ratio of structures of medium-to-large complexity. The use of multiple alloy wires during WAAM is of particular interest as the chemical composition of the deposit can be adjusted according to the structure’s requirements without the limitation of commercially available welding wires. Additionally, the local chemical compositions may be adjusted yielding novel physical and mechanical properties of such functionally graded materials (FGM). The present work explores options for the fabrication of structures using multiple feedstock wires to a deposit a FGM and b deposit alloy compositions of commercially unavailable materials. For the deposition gas tungsten arc welding (GTAW) is used. Resultant materials are characterized regarding chemical composition, microstructure and mechanical properties. Utilizing tailored processing conditions the fabrication of a chemical gradient was verified by optical emission spectroscopy along the specimen height with the results for Si. The major findings of the presented research can be concluded as follows: WAAM using two feedstock wires is not only feasible but allows for flexibility in the processing routine; The adjustment of new alloy compositions by mixing the respective feedstock wires in situ during processing is possible with sufficient intermixing; Microstructures and resultant properties can thereby be adjusted locally; The outcomes of this work expand the applicability of WAAM as additional design freedom is gained for the fabrication of structures and components.

Biography

Thomas Klein studied Materials Science at the Montanuniverstät Leoben, Austria, where he received his Masters degree in 2013 and his PhD in 2017 for the characterization of phase transformations, microstructure formation and mechanical properties of inter metallic alloys based on TiAl. After a Post Doc assignment at the Materials Center Leoben (MCL), Austria, from 2017 - 2019, where he focused on the development of advanced high strength steels, Thomas Klein joined the LKR Light Metals Technologies Ranshofen working on the development of novel light-metal alloy system for wire-arc additive manufacturing.