Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Electromagnet Assisted Laser-GMA Hybrid Welding of Thick-Walled Structural Steels and Its Influence on the Weld Seam Properties
    (Fraunhofer Verlag, 2023)
    Üstündag, Ömer
    ;
    Rethmeier, Michael
    Currently, thick-walled steels are mostly joined using arc-based welding processes in the industry. The industrial use of alternative welding processes, such as the laser-gma hybrid welding process, are limited due to some process-specific challenges, such as the gravity-induced droplet formation at the weld root, limited gap bridgeability and a high sensitivity to manufacturing tolerances, or poor mechanical properties due to high cooling rates. In this work, laser-gma hybrid welding with contactless electromagnet backing is presented. With this innovative process, it was possible to join plates with a thickness up to 30 mm using a 20-kW fiber laser. In addition, the gap bridgeability could be significantly increased. The mechanical properties such as the tensile strength and Charpy impact strength could also be increased. With the implementation of this process in industry, e.g. in shipbuilding or wind tower fabrication, the productivity can be significantly increased compared to the arc-based welding processes, such as the submerged arc welding.
  • Publication
    Microstructure and Mechanical Properties of Refill Friction Stir Spot Welding of AM50 Cast Magnesium Alloy
    (Fraunhofer Verlag, 2022)
    Fu, Banglong
    Magnesium (Mg) alloys have been considered as an important material in aerospace, sport, electrical, railway systems and, most importantly, in automotive industry, which comprises 80% of Mg usage. In order to enlarge its usage, appropriate welding methods should be investigated. Refill friction stir spot welding (refill FSSW) is a novel solid-state welding technology. Due to the significant merits of keyhole-free weld, improved mechanical properties, etc., it has been successfully used for the welding of Al-based similar and dissimilar combinations. However, studies concerned with Mg alloys are limited. The feasibility of refill FSSW of casting Mg alloy AM50 was investigated firstly. Defect-free welds with flat surface and high performance were obtained successfully. Moreover, a modified method, differential rotation refill FSSW (DR-refill FSSW), was developed. DR-refill FSSW provides a new and effective strategy for improving the performance of spot welds based on microstructural engineering.