Wire-based additive manufacturing using an electron beam as heat source

• Published in: Welding in the world Vol. 62; no. 2; pp. 267 - 275
• Main Authors: Fuchs, J., Schneider, C., Enzinger, N.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2018; Springer Nature B.V
• Subjects: Additive manufacturing; Additive Manufacturing and Associated NDT; Arc heating; Arc welding; Beads; Chemistry and Materials Science; Complexity; Core wire; Electron beams; Electrons; Energy distribution; Feed rate; High vacuum; Laser beam welding; Low carbon steels; Materials Science; Metallic Materials; Process controls; Process parameters; Research Paper; Solid Mechanics; Substrates; Theoretical and Applied Mechanics; Titanium; Vacuum chambers; Welding; Wire; Electron beam; Process development; Mild steel; Additive manufacturing
• ISSN: 0043-2288; 1878-6669
• DOI: 10.1007/s40194-017-0537-7

Many standard welding processes, such as gas metal arc-, laser-, or electron-beam welding, can be used for additive manufacturing (AM) with only slight adaptions. Wire-based additive manufacturing provides an interesting alternative to powder-based processes due to their simplicity and comparatively high deposition rates. The use of an electron beam as heat source for AM offers unique possibilities for construction of components due to its inherent flexibility. It is possible to efficiently build bigger parts with comparably fine features and high complexity. Furthermore, additional working steps such as preheating, surface modification, welding, or heat treatments can be implemented into the additive manufacturing process and thereby alleviate the bottleneck of the evacuation of the vacuum chamber. Aside from this, the ultra high vacuum atmosphere can be beneficial, when working with reactive materials such as Ti or Mo. The intrinsic complexity of electron-beam additive manufacturing (EBAM) can make a stable and reproducible process control quite challenging. In this study, the influence of the main process parameters, such as heat input, energy distribution, wire feed, and their complex interactions are investigated. Based on single beads on a mild steel substrate using an unalloyed metal core wire (G4Si1), the correlation between the process parameters such as beam current, acceleration voltage, speed, wire feed rate and position, and the resulting bead geometry, height, width and penetration was studied. These findings were used to successfully establish a multi pass layout consisting of one to six beads next to each other and up to ten layers in height. For basic characterization, metallographic analysis as well as hardness measurements were performed.