Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Process advantages of laser hybrid welding compared to conventional arc-based welding processes for joining thick steel structures of wind tower
    ( 2023-12-22)
    Brunner-Schwer, Christian
    ;
    Üstündag, Ömer
    ;
    Bakir, Nasim
    ;
    Gumenyuk, Andrey
    ;
    Rethmeier, Michael
    The most common welding processes when joining thick-walled steels in the industry are arc-based welding processes such as GMAW or SAW. For this purpose, the sheets are joined in multi-layer technique, which can lead to productivity losses due to high welding times. The process-specific challenges in welding thick steels using multi-layer technique relate to the high heat input from the process. Therefore, alternative welding processes are being actively sought. A suitable alternative is provided by beam-based welding processes such as the laser hybrid welding processes, which are characterized by deep penetration welds and lower heat input. With implementation of the laser hybrid welding process in the heavy industry, such as the wind tower industry, economic benefits can be reached such as the increase in productivity by reducing the layer number, and the lower consumption of filler material and energy. When comparing SAW welded 25 mm thick steels in five to six layers and single-pass laser hybrid welding, the welding time can be reduced more than 80 % and the costs of filler material, flux and energy can be saved up to 90 %. However, the industrial use of the laser hybrid welding process is still limited to applications, where the material thickness does not exceed 15 mm due to some process-specific challenges such as the sagging, sensitivity to manufacturing tolerances such as gaps and misalignment, limited filler wire mixing, and deteriorated mechanical properties resulting from high cooling rates. To overcome these challenges, a contactless electromagnetic backing based on an externally applied AC magnetic field was used. Eddy currents are induced due to the oscillating magnetic field, and an upward-oriented Lorentz force is generated to counteract the droplets formed due to gravitational forces. It allows to weld up to 30 mm thick structural steels in a single-pass with a 20-kW fiber laser system. Additionally, the gap bridgeability and the misalignment of edges were increased to 2 mm when welding 20 mm thick steels. With the aid of the AC magnetic field, a vortex was formed in the weld root, which had a positive effect on the filler wire mixing.
  • Publication
    Laserstrahlhybridschweissen von Türmen für Windkraftanlagen - Ökonomische und ökologische Vorteile
    ( 2023-12-19)
    Üstündag, Ömer
    ;
    Bakir, Nasim
    ;
    Brunner-Schwer, Christian
    ;
    Knöfel, Frieder
    ;
    Gook, Sergej
    ;
    Gumenyuk, Andrey
    ;
    Rethmeier, Michael
    Das Laserstrahlhybridschweißen ist beim Schweißen von Türmen für Windkraftanlagen eine Alternative zum Unterpulver schweißen von Dickblechen in Mehrlagentechnik und bietet hier ökonomische und ökologische Vorteile. Der industrielle Einsatz des Verfahrens ist jedoch durch prozessspezifische Herausforderungen eingeschränkt. Die im Beitrag beschriebene kontaktlose elektromagnetische Badstütze dient zur Erweiterung des Verfahrenspotenzials im Dickblechbereich >15 mm.
  • Publication
    Mechanical properties of laser welded joints of wrought and heat-treated PBF-LB/M Inconel 718 parts depending on build direction
    ( 2023)
    Simón Muzás, Juan
    ;
    Brunner-Schwer, Christian
    ;
    Hilgenberg, Kai
    ;
    Rethmeier, Michael
    Laser-based Powder Bed Fusion of Metal (PBF-LB/M) is a broadly used metal additive manufacturing (AM) method for fabricating complex metallic parts, whose sizes are however limited by the build envelope of PBF-LB/M machines. Laser welding arises as a valid joining method for effectively integrating these AM parts into larger assemblies. PBF-LB/M components must usually be stress-relieved before they can be separated from the build plate. An additional heat treatment can be beneficial for obtaining homogeneous mechanical properties across the seam or for the formation of desired precipitations in nickel-based-alloys. Therefore, the tensile performance of laser welded hybrid (AM/wrought) and AM-AM tensile samples of Inconel 718 is examined after undergoing three different heat treatments and considering three relevant build directions. It can be shown that the build orientation is an influencing factor on weld properties even after two applied heat treatments.
  • Publication
    Laserstrahlhybridschweißen von Türmen für Windkraftanlagen
    ( 2022-08-29)
    Üstündag, Ömer
    ;
    Bakir, Nasim
    ;
    Brunner-Schwer, Christian
    ;
    Knöfel, Frieder
    ;
    Gook, Sergej
    ;
    Rethmeier, Michael
    ;
    Gumenyuk, Andrey
    Das Laserstrahlhybridschweißen ist beim Schweißen von Türmen für Windkraftanlagen eine Alternative zum Unterpulverschweißen von Dickblechen in Mehrlagentechnik und bietet hier ökonomische und ökologische Vorteile. Der industrielle Einsatz des Verfahrens ist jedoch durch prozessspezifische Herausforderungen eingeschränkt. Die im Beitrag beschriebene kontaktlose elektromagnetische Badstütze dient zur Erweiterung des Verfahrenspotenzials im Dickblechbereich >15 mm.