Joining of Inconel 718 and 316 Stainless Steel using electron beam melting additive manufacturing technology

Abstract

Joining of dissimilar metals using high energy-density beams such as lasers and electron beams offer several advantages including precision, narrow fusion zones, and narrow heat affected zones (HAZ) that consequently result in reduced part distortion when compared to traditional joining processes. When high energy-density beams are combined with the design freedom offered by additive manufacturing (AM), or a layer-by-layer part fabrication process, it becomes possible to manufacture complex multi-material parts with improved joint characteristics resulting from controlled process parameters. Complex multi-material parts can be achieved that have tremendous impact on applications ranging from nuclear power plant components to repair applications. This research explores the feasibility of joining Inconel 718 with 316L Stainless Steel, and vice versa, by utilizing electron beam melting (EBM) additive manufacturing, a class of powder bed fusion technology. The use of this process can help avoid the use of filler materials, provides an evacuated processing environment resulting in limited contamination of oxides and nitrides, and can provide a high quality metallurgical joint while minimizing the thermal damage to surrounding material. Multi-material components were fabricated and the joint interfaces were characterized. Assessments of the interfaces revealed minimized thermal effects from the process and finer weld joints.