Preliminary Studies on Fatigue and Fracture Toughness of Steel Wire Arc Additively Manufactured Structural Products

Structural element fabrication using direct energy deposition, specifically using wire arc additive manufacturing (WAAM) methods, is an emerging technology being explored by many industries. The ability to produce complex shapes while achieving high cost-effectiveness and scalability has received notable attention given the increasing demands of the structural steel fabrication industry. Moreover, the introduction of automation in the additive manufacturing (AM) process by robotically producing the elements using gas-metal arc welding (GMAAM) holds promise to enhance the constructability of structural steel products. Despite abundant research conducted on small-scale metallic AM products, the production of large-scale ferritic components on a scale suitable for civil engineering applications using GMAAM introduces new process variables and structural integrity challenges. This brings forth uncertainties regarding the GMAAM material and its performance such as: How do GMAAM materials perform in cyclic loading in comparison with the traditional product forms and welded connections (as per CSA W59)? And how do internal voids or defects within the GMAAM products affect the fracture toughness? Furthermore, the lack of standardization of AM technology in terms of manufacturing guidelines and practices is another major challenge that is yet to be tackled. As a first step towards addressing these issues, the current paper presents recent tests on GMAAM material samples to better understand the static properties, impact toughness, and fatigue crack propagation behaviour of these materials.