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Metals 2017, 7(10), 443; https://doi.org/10.3390/met7100443

The Influence of the Powder Stream on High-Deposition-Rate Laser Metal Deposition with Inconel 718

1
Fraunhofer Institute for Laser Technology ILT, Steinbachstr. 15, 52074 Aachen, Germany
2
Chair for Laser Technology, RWTH Aachen University, Steinbachstr. 15, 52074 Aachen, Germany
3
Chair for Digital Additive Production DAP, RWTH Aachen University, Steinbachstr. 15, 52074 Aachen, Germany
*
Author to whom correspondence should be addressed.
Received: 1 September 2017 / Revised: 10 October 2017 / Accepted: 12 October 2017 / Published: 20 October 2017
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Abstract

For the purpose of improving the productivity of laser metal deposition (LMD), the focus of current research is set on increasing the deposition rate, in order to develop high-deposition-rate LMD (HDR-LMD). The presented work studies the effects of the powder stream on HDR-LMD with Inconel 718. Experiments have been designed and conducted by using different powder feeding nozzles—a three-jet and a coaxial powder feeding nozzle—since the powder stream is mainly determined by the geometry of the powder feeding nozzle. After the deposition trials, metallographic analysis of the samples has been performed. The laser intensity distribution (LID) and the powder stream intensity distribution (PID) have been characterized, based on which the processes have been simulated. Finally, for verifying and correcting the used models for the simulation, the simulated results have been compared with the experimental results. Through the conducted work, suitable boundary conditions for simulating the process with different powder streams has been determined, and the effects of the powder stream on the process have also been determined. For a LMD process with a three-jet nozzle a substantial part of the powder particles that hit the melt pool surface are rebounded; for a LMD process with a coaxial nozzle almost all the particles are caught in the melt pool. This is due to the different particle velocities achieved with the two different nozzles. Moreover, the powder stream affects the heat exchange between the heated particles and the melt pool: a surface boundary condition applies for a powder stream with lower particle velocities, in the experiment provided by a three-jet nozzle, and a volumetric boundary condition applies for a powder stream with higher particle velocities, provided by a coaxial nozzle. View Full-Text
Keywords: laser metal deposition (LMD); direct metal deposition (DMD); HDR-LMD; Inconel 718 (IN718); coaxial powder feeding; powder intensity distribution; laser intensity distribution laser metal deposition (LMD); direct metal deposition (DMD); HDR-LMD; Inconel 718 (IN718); coaxial powder feeding; powder intensity distribution; laser intensity distribution
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Zhong, C.; Pirch, N.; Gasser, A.; Poprawe, R.; Schleifenbaum, J.H. The Influence of the Powder Stream on High-Deposition-Rate Laser Metal Deposition with Inconel 718. Metals 2017, 7, 443.

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