Wire-arc additive manufacturing (WAAM): investigation of process dynamics, material insights, and application prospects

Wire-arc additive manufacturing (WAAM), more recently referred to as directed energy deposition-arc (DED-arc), is emerging as a cost-effective solution with high material deposition rate and lower lead time. Thus, making it one of the most desirable Additive Manufacturing (AM) process for large-scale fabrication. However, extensive research is needed to realise the benefits of this technology. This thesis comprehensively evaluates the performance and prospectives of WAAM processes. The first study investigated different metal transfer modes and their interactions with input variables. The second study explored various deposition strategies for test walls and cubic samples on their built structure and mechanical properties. In addition, this study shows the influence of layer-stacking in the building direction on microstructural evolution and material hardness. The third study was based on a detailed analysis of cored-wire in two different WAAM process variants i.e. GMA and PTA-based WAAM. A solid wire of same chemical composition was employed for the comparative study. Different shielding gases were also investigated for GMA process to witness their influence on the process outcome. Another study was followed by depositing a hardfacing cored-wire with the properties of corrosion resistance to investigate the WAAM process in melting and deposition of such wire consumables. PTA and GMA processes with different shielding gases were used for hardfacing cored-wire to explore the opportunities and challenges of depositing such hard-to-deposit materials. The last study covered a process-driven comparative study on wire-fed DED processes based on electric arc, plasma and laser sources such as GMA, PTA and LMD. Thus, the research provides important insights on WAAM, by exploring it from a process, product and application perspective.