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Additive Manufacturing: Directed Energy Deposition 3
10:00am - 11:00am
Session Chair: Nicole Emminghaus, Laser Zentrum Hannover e.V., Germany
Location:Room 2 ICM
10:00am - 10:15am
Analysis and recycling of bronze grinding waste to produce maritime components using directed energy deposition
Vinzenz Müller1, Angelina Marko1, Tobias Kruse2, Max Biegler1, Michael Rethmeier1,3
1Fraunhofer Institute for Production Systems and Design Technology IPK, Germany; 2Mecklenburger Metallguss GmbH, Germany; 3Bundesanstalt für Materialforschung und -prüfung (BAM), Germany
Additive manufacturing promises a high potential for the maritime sector. Directed Energy Deposition (DED) in particular offers the opportunity to produce large-volume maritime components like propeller hubs or blades without the need of a costly casting process. The post processing of such components usually generates a large amount of aluminum bronze grinding waste. The aim of the presented project is to develop a sustainable circular AM process chain for maritime components by recycling aluminum bronze grinding waste to be used as raw material to manufacture ship propellers with a laser-powder DED process. In the present paper, the main challenges and promising measures and methods to recycle metallic grinding waste are shown. Two types of grinding waste are investigated using a CamSizer particle analysis system and compared to commercial DED powder. To be able to compare the material quality and to verify DED process parameters, semi-academic sample geometries are manufactured.
10:15am - 10:30am
Evaluation of steady state via thermography during laser and wire based directed energy deposition
Anton Emil Odermatt, Nikolai Kashaev
Helmholtz-Zentrum Geesthacht, Institute of Materials Mechanics, Department of Laser Processing and Structural Assessment
Additive manufacturing of structures in one continuous deposition process is appealing because defects at the start and end-points of a track are avoided. For the evaluation of process stability, a steady state process needs to be reached. A methodology for the determination of the interpass temperature for processes using a positioner for movement of the work piece has been developed. This methodology was applied to a laser and wire based directed energy deposition process. The approach of the steady state process can be described by an exponential growth law. From the interpass temperature a cooling rate can be calculated. The evolution of the interpass temperature can be used for process control and the cooling rate can be related to material properties. A comparison with results from the literature shows that the convergence rate is mainly dependent on the power level of the energy source and the size of the structure.
10:30am - 10:45am
Influence analysis of the layer orientation on mechanical and metallurgic characteristics of DED manufactured parts
Florian M. Dambietz1, Tobias S. Hartwich1, Julian Scholl-Corrêa2, Dieter Krause1, Peter Hoffmann2
1Hamburg University of Technology, PKT; 2ERLAS Erlanger Lasertechnik GmbH
With an increasing trend in product individualization, manufacturing custom-designed solutions and focusing on the explicit industry’s needs are crucial to the manufacturer’s success. Especially within high-tech industries such as aerospace industry, high-strength, large-sized but still lightweight metal parts are required. Although the Direct-Energy-Deposition (DED)-technology offers a proven outset point for targeting this issue, there are few material-, metallurgic-, process-, and geometry specific data available to support the initial design process of such parts. This contribution presents a profound study of different steel- and aluminium materials with respect to their metallurgic and mechanical characteristics. Using a state-of-the art DED-Laser system, tensile test specimens have been manufactured with alternative layer orientations. These specimens are analysed with regard to the required milling oversize, heat-induced stress deformation, metallurgic characteristics and their tensile characteristics. As a result of this investigation, a suitable baseline for the future generation of a DED design-by-feature catalogue is given.
10:45am - 11:00am
Investigation on laser cladding of rail steel without preheating
Christian Brunner-Schwer1, Max Biegler1, Michael Rethmeier3,1,2
1Fraunhofer Institute for Production Systems and Design Techology, Pascalstraße 8-9, 10587, Berlin, Germany; 2Bundesanstalt für Materialforschung und –prüfung, Unter den Eichen, 87 12205, Berlin, Germany; 3Institute of Machine Tools and Factory Management, Technische Universität Berlin, Pascalstraße 8-9, 10587, Berlin, Germany
The contact between train wheels and rail tracks is known to induce material degradation in the form of wear, and rolling contact fatigue in the railhead. Rails with a pearlitic microstructure have proven to provide the best wear resistance under severe wheel-rail interaction in heavyhaul application. High speed laser cladding, a state-of-the-art surface engineering technique, is a promising solution to repair damaged railheads. However, without appropriate preheating or processing strategies, these steel grades lead to martensite formation and cracking during deposition welding.
In this study, laser cladding of low-alloy steel at very high speeds were investigated, without preheating the railheads. Process speeds of up to 27 m/min and Laser power of 2 kW are used. The clad, heat affected zone and base material are examined for cracks and martensite formation by hardness tests and metallographic inspections. A methodology for process optimization is presented and the specimens are characterized for suitability.