Further development of manufacturing methods and metallic alloys is crucial for creating next generation energy production systems capable of improved strength, toughness, creep, and/or corrosion resistance. Many commercially produced metal alloys have commercially available filler metals that were developed to suitably join and meet the performance requirements of the application. These commercial filler metals are now being used in wire arc additive manufacturing applications that can tolerate near-net shaped components and are optimal for high deposition rates. Additive manufacturing using wire feedstock is often substantially cheaper than powder feedstock, and impurity concentrations are often lower. In addition, weld wire performance for multi-pass welding, cladding, and build-up repairs (additive manufacturing) is backed by decades of experimental data and service applications.
To further expand the capabilities of arc additive manufacturing, a multi-wire arc additive manufacturing system (m-WAAM) was developed that uses gas tungsten arc welding and can independently introduce three weld wires into a single weld pool. By using this system, it is possible to expand metallic alloy selections and optimize material properties and/or weldability performance using commercially available wire. Additionally, it is possible to selectively grade chemical compositions to alter material properties in specific regions. This research analyzed computational thermodynamic predictions, weld metal dilutions, and microstructures at varying proportions of nickel-base alloy wires deposited via the m-WAAM process. The overall composition of the weld pool was a result of the dilution of the substrate and rate/volume of filler metals added. This research demonstrated that weld metal composition, when grading two or three commercially available nickel alloy filler metals, may be more complex than a rule-of-mixture assumption based on individual weld wire feed rates.