Publications
Here you find some OSCAR-publications in English language. For our German publications, visit: https://oscar-plt.de/wissen/publikationen/
T Gustmann, F Silze, U Jasnau, Ch Gajda and G Trensch: Additive Repair of Cast Iron Materials using Coaxial Laser Wire Cladding
IOP Conference Series: Materials Science and Engineering (2025)
Abstract
In contrast to most steels, almost all cast iron materials are considered problematic in terms of welding. Today, arc-based welding of dissimilar bonds and the associated welding sequences at low pre-heating temperatures are established in the industrial environment. However, this processing routine, e.g. for repair or cladding, often appears to be no alternative for many components, where a low heat input and a wider range of filler metals in contrast to the application need to be considered. In this context, laser-based technologies constitute valuable tools for cast-iron repair and are seen as future approaches for thermal processing of demanding materials without the need for pre- or post-heating.
Nowadays, the possibilities offered by wire-based laser processes allow for material-efficient manufacturing approaches, such as the repair and processing of worn-out, cast-iron components. As an example, the successful repair of cast iron materials, viz. GJS and GJL, using a self-developed coaxial laser wire cladding technology is presented. The laser system has been used to investigate cast-iron repair by hot wire deposition without pre-heating the substrates. Selected process strategies with defined parameters and tool path sequences have been used to repair industrially applied cast-iron parts. While the heat input is mainly dissipated in the filler metal during processing, a low dilution and minimal martensite formation in the transition zone could have been achieved under different process conditions (welding position, filler metal material – NiTi4, FeCrMoVC). The gained flexibility in cast-iron repair addresses the potential for future concepts in the field of industrial remanufacturing.
Dr. Tobias Gustmann, Dr. Frank Silze, Sebastian Bibrack, Dr. Michael Schnick: Wire-based Laser Metal Deposition of Nickel and Iron-based alloys for Repair of Gas Turbine Housings using a Direct Diode Laser System [conference presentation]. Lasers in Manufacturing (LiM) (2023)
The laser wire deposition process is increasingly gaining application in industry due to its process-specific advantages. In addition to the wide availability due to the already long-standing use of the wires in the classic welding processes and the relatively simple handling (storage, health protection), above all the existing certifications of numerous wire alloys are positive arguments for the application in the industrial environment.
Compared to the already more established powder process, however, the wire process requires more comprehensive process control. There is a small process window, which must be kept stable by control mechanisms. In the lecture, various solutions on the way to a controlled and automated wire process will be presented and examples from the repair of large components in opencast mining will be explained, which offer an interesting solution approach from the point of view of sustainability.
Dr. Frank Silze and Dipl.-Ing (FH) Sebastian Bibrack: DED-LB Applications of DED-LB with wire in repair, functionalisation and additive manufacturing [conference presentation]. 74th IIW Annual Assembly and International Conference (2021)
B. Elsner, F. Silze, A. Marquardt: IMProVing directed energy deposition, PhotonicsViews (4/2021)
Directed energy deposition (DED) is a powerful additive manufacturing tech nique that combines a high degree of freedom in design with relatively high deposition rates that can increase throughput. DED structures are created by repeatedly depositing weid beads from powder or wire feedstock, which also makes it an attractive technique for hybrid manufacturing because features can be added to a base component. However, the numerous heating and cooling cycles involved in the deposition process result in a complex thermal history that can entail distort the entire component.
F.Silze, M. Schnick, I. Sizova, M. Bambach: Laser Metal Deposition of Ti-6Al-4V with a Direct Diode Laser Set-up and Coaxial Material feed. Procedia Manufacturing, (2020)
The production of components from the titanium alloy Ti-6Al-4V is of great importance for many industrial fields, especially for the aerospace industry. Laser metal deposition (LMD) processes can be used either for manufacturing of components or repair. The majority of LMD set-ups use a concentrical laser and a powder feed through nozzles focusing the powder on a spot. Gas shielding is problematic in such set-ups, which hence require the use of protective gas chambers. The present paper details results on laser metal deposition (LMD) of Ti-6Al-4V with a new direct diode laser head. In the LMD set-up, six 200W laser diodes are positioned on a circle around the feeding lance and create a laser spot with a diameter of ~0.9 mm. The laser beam is thus directly generated inside the head. The set-up allows for co-axial feed of powder or wire material. Due to the arrangement of the single laser beams and the coaxial filler material feeding, a direction independent welding process is possible. The Ti-6Al-4V specimens deposited with the LMD head show a clean surface and a dense microstructure. The results indicate that the new diode laser head allows for a direction-independent LMD process with low oxygen take-up.
Markus Bambach, Irina Sizova, Frank Silze, Michael Schnick: Hot workability and microstructure evolution of the nickel-based superalloy Inconel 718 produced by laser metal deposition. Journal of Alloys and Compounds 740 (2018) 278-287
The manufacturing of parts from nickel-based superalloys used to be dominated by conventional processes such as forging, which use expensive dies and require cost-intensive machining operations to produce the final part shape, due to the limited ability of the forging process to produce near-net shape parts. The ongoing efforts in developing additive manufacturing (AM) processes could promote an increasing competition of AM with traditional processes. AM offers various benefits such as near neat shaping, integration of functions into parts and the possibility to locally engineer components. However, manufacturing costs and process time in additive manufacturing rise rapidly with part size. For many applications, the disadvantages of AM and forging operations could be levered by mating both processes to new process chains. Adapted pre-forms for forging operations could be created by printing onto existing stock material, thus allowing to reduce the number of forging steps and to avoid high material waste. However, up to the present day, only very limited knowledge is available on the forming behavior of additively manufactured materials.
In this paper, the hot deformation behavior and the associated microstructural changes of samples made from the nickel-based superalloy Inconel® 718 using laser metal deposition (LMD) have been studied using isothermal hot-compression tests. The as-built state is shown not to be suitable for hot working due to the presence of the Laves phase, which has to be removed by heat treatment. Wrought samples and heat-treated LMD samples are compared with respect to their hot working behavior. Pronounced shifts of characteristic points of the flow curves between both types of material are observed. The results show that heat-treated LMD samples are well hot workable, preferentially at higher values of the Zener-Hollomon parameter where incipient yield and initial work hardening occur at lower stress levels.
