Description

Additive manufacturing processes have undergone significant development in regard to process management and reproducibility. Porosity, crack formation and similar defects can be reliably avoided through process control for a multitude of materials. This also applies to wire laser direct energy deposition (wire L-DED), which offers standardized feedstock material and direct controllable flow of mass. However, the process inherent microstructure remains fundamentally unaffected by parameter variations within typical process configurations. This microstructure is characterized by coarse columnar grains with a distinct fiber texture along the build direction. The underlying cause is the presence of a strong directional heat flux from the melt pool through the deposited material to the substrate. Consequently, as-built components demonstrate anisotropic mechanical properties with significantly lower tensile strength in build direction. One possible approach to inducing grain refinement and promoting the formation of an isotropic microstructure is the application of ultrasonic waves to the melt pool during solidification This lecture presents an approach to introducing ultrasonic waves to the wire L-DED process. An ultrasound system was developed, integrated in a laser wire deposition machine and a suitable process window has been established. A disruption of the highly directional solidification, resulting in a randomized texture as well as finer grains, has been confirmed by means of scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) (dm = 284,5 ?m without ultrasound, dm = 130,4 ?m with ultrasound).

Contributing Authors

  • Jacob Mätje
    Fraunhofer Institute for Material and Beam Technology IWS
  • Maximilian Heidowitzsch
    Fraunhofer Institute for Material and Beam Technology IWS
  • Mirko Riede
    Fraunhofer Institute for Material and Beam Technology IWS
  • Conrad Samuel
    Fraunhofer Institute for Material and Beam Technology IWS
  • Leonid Gerdt
    Fraunhofer Institute for Material and Beam Technology IWS
  • Jörg Kaspar
    Fraunhofer Institute for Material and Beam Technology IWS
  • Elena Lopéz
    Fraunhofer Institute for Material and Beam Technology IWS
  • Frank Brückner
    Fraunhofer Institute for Material and Beam Technology IWS | Luleå University of Technology
  • Christoph Leyens
    Fraunhofer Institute for Material and Beam Technology IWS | Technische Universität Dresden
Jacob Mätje
Fraunhofer Institute for Material and Beam Technology IWS
Track: Laser Additive Manufacturing
Session: DEDAM Process and Materials II
Day of Week: Monday
Date/Time:
Location: Salon 4-6

Keywords

  • Grain Refinement
  • Laser Wire Direct Energy Deposition
  • Microstructure Tailoring
  • Ultrasonic Engineering