Public Thesis Defense of Rafael GOMES NUNES SILVA - IMMC
sst |
DED-Arc Manufacturing of High Strength Aluminium 7075 Alloy and Weldability Assessment of Aluminium Alloy Parts Produced by Additive Manufacturing
Tuesday March 31st, 2026 - 9:00am - Belgian Welding Insitute Room 1.15 Technologiepark-Zwijnaarde 48 - 9052 Ghent, Belgium
The increasing demand for lightweight, high-performance structural components in aerospace, defence and energy sectors has intensified interest in aluminium alloys produced by additive manufacturing. Among these materials, high-strength 7075 alloys offer outstanding strength-to-weight ratios but remain highly susceptible to hot cracking, hydrogen-induced porosity and thermal instability, making their processing by fusion-based additive manufacturing particularly challenging. Repeated thermal cycling, complex solidification behaviour and alloy-specific metallurgical constraints significantly affect microstructural evolution, defect formation and overall process robustness. A structured manufacturing framework was established to enable reliable DED-Arc production of high-strength aluminium components, progressing from weldable reference alloys (ER5183 and ER2219) to the crack-sensitive ER7075. The results demonstrate that DED-Arc processing of ER7075 is feasible within a narrow, metallurgically governed process window. Filler metal quality, including surface condition and chemical homogeneity, was identified as a decisive parameter influencing arc stability, droplet transfer and hydrogen uptake. Equally critical is thermal management, where strict control of heat input, interpass temperature and deposition strategy governs melt pool stability, microstructural development and defect sensitivity. Beyond manufacturability, the integration of additively manufactured aluminium components through welding was shown to depend strongly on the additive manufacturing process and resulting material state. While DED-Arc components with low defect content exhibit weldability comparable to conventional alloys, PBF-LB materials show increased sensitivity to fusion welding due to inherent porosity. Solid-state joining, particularly Friction Stir Welding, provides a robust alternative largely independent of initial defect populations. Overall, a coupled process-chain perspective, linking additive manufacturing, material behaviour and subsequent joining process, proves essential for achieving reproducible quality and supporting the industrial qualification of aluminium structures.
Jury members
Prof. Dr. Aude Simar (UCLouvain) Supervisor
Prof. Dr. Wim De Waele (Ghent University) Supervisor
Prof. Dr. Nicolas Moes (UCLouvain) Co-Chair
Prof. Dr. Patrick De Baets (Ghent University) Co-Chair
Dr. Camille van der Rest (UCLouvain) Secretary
Dr. Koen Faes (Belgian Welding Institute)
Prof. Dr. Constantinos Goulas (Universiteit Twente, The Netherlands)
Prof. Dr. Ghazal Moeini (Westfalische Hochschule, Germany)
Honorary Prof. Dr. Roumen Petrov (Ghent University)