| Abstract Scope |
Functionally graded materials (FGM) produced by multi-material Tandem Wire-Arc Directed Energy Deposition offer significant potential for joining, repair, and manufacturing of components with locally tailored properties. While previous studies focus on microstructure and mechanical performance, industrial implementation is governed by process stability and control. This work investigates two low-alloy steels of different strength classes (ER70S-6 and ER120S-G), applying continuous and discrete grading strategies in both build (between layers) and deposition (within the layer) directions. Addressing process behaviour, including dilution control, bead formation, and transition stability. The results demonstrate that grading strategies and wire mixing significantly influence process stability and gradient formation. In particular, the arrangement of wires (leading or trailing), welding parameters, and thermal conditions are key factors governing defect formation and transition stability. These findings emphasize that process control is essential for achieving defect-free FGM structures and support the development of data-driven, sensor-assisted manufacturing for repair and joining applications. |