Wire-Arc Additive Manufacturing of Reduced Activation Ferritic Martensitic (RAFM) Steel

RAFM steel has been considered as the candidate material for an in-vessel component of the fusion wall reactor. Known as F82H in Japan and Eurofer-97 in Europe, RAFM steel is not commercially available. The goal of this research project is to fabricate and study the technical feasibility of producing RAFM steel welding wire with wire arc AM. Metal-cored wire is a tubular electrode comprised of an outer metal sheath with alloying powdered materials inside the core. Applications of such wire include but not limited to welding, thermal spray, cladding and additive manufacturing (AM). The advantage of using the metal-cored wire is that a higher deposition rate, higher side-wall fusion, can be achieved, and more important, special alloys for special applications can be manufactured at relatively lower cost. A preliminary investigation of wire arc AM of RAFM steel was carried out using Ar-CO2 (c-25) gas. A design of experiments with GMAW based power source waveform using the metal cored wire was conducted to study the printability. The microstructure and mechanical properties (hardness and toughness) was tested, and the data were analyzed and compared with the literature.