TY - GEN A1 - Wasilewski, Eric A1 - Wolf, Matthias A1 - Zhang, Wei A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Cu/LaCrO₃ joining by local melt infiltration through laser cladding T2 - Journal of the American Ceramic Society N2 - Direct bonding of copper and porous LaCrO₃ without an extra filler interlayer was successfully completed using local and fast Cu‐infiltration through laser cladding. This significantly reduced the susceptibility of the ceramic to cracking. A high‐speed camera investigation into the wetting and infiltration behavior of a Cu‐melt into LaCrO₃ with a porosity of ~63 vol% was performed. By adjusting the focal distance with a constant laser power of 300 W, the Cu‐melt was rapidly infiltrated into the ceramic preform in 10 seconds. This was completed under atmospheric air conditions, without added inert gas. The joining process developed can be used to fabricate ceramic/metal joints with targeted (micro‐) structure properties by adjusting the infiltrated melt and the infiltration depth, which would be suitable for many applications, such as multifunctional devices, solid oxide fuel cells or heating elements. Y1 - 2018 U6 - https://doi.org/10.1111/jace.15767 SN - 1551-2916 SN - 0002-7820 VL - 101 IS - 10 SP - 4472 EP - 4472 ER - TY - GEN A1 - Wasilewski, Eric A1 - Kaneneks, Michael A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Laserstrahlschweißen – Verzugs- und Kaltrissminimierung durch simulationsbasierte Steuerung T2 - DVD Congress 2020 : Große Schweißtechnische Tagung : DVS Campus : Vorträge der Online-Veranstaltungen vom 14. bis 18. September 2020 N2 - Leichtbau und das Streben nach Ressourcen- und Energieeffizienz fördern in den letzten Jahren vermehrt den Einsatz hochfester Stähle. Das Laserstrahlschweißen dieser Werkstoffe wird in der industriellen Großserienferti-gung zur effizienten Herstellung hochpräziser Bauteile und Komponenten mit höchsten Qualitätsanforderungen eingesetzt. Die Vermeidung schweißbedingter Fehler wie Schweißverzug und Kaltrissbildung sind dabei von ent-scheidender Bedeutung. Konventionelle Anwendungen erfüllen diesen Anspruch derzeit bedingt durch sehr enge Prozesstoleranzen und die Auswahl unkritischer Werkstoffe, was die Potentiale der Fügeverbindung begrenzt. Auf Basis von FE-Schweißprozesssimulationen konnten Konzepte entwickelt werden, welche eine Verzugs- und Riss-minderung durch aktive Steuerung des Laserschweißprozesses ermöglichen. Die zugrundeliegenden Modelle be-rücksichtigen zum einen das schweißbedingte Temperaturfeld, Gefügeumwandlungen und Eigenspannungen für die Berechnung des Verzugs. Zudem wird die lokale Wasserstoffkonzentration berechnet und die Ergebnisse der Schweißprozesssimulation mittels eines Kaltrisstools bewertet, welches werkstoffspezifische Risskriterien enthält. Die Fähigkeit das Verzugs- und Kaltrissverhalten abzubilden, eröffnet die Möglichkeit zur Parametervariation. Aus den erhobenen Daten wurden Konzepte der aktiven Krafteinleitung mit einer dynamischen Werkstückeinspannung abgeleitet, die zu Verzugs- und Kaltrissminimierung führen und die Schweißbarkeit hochfester Werkstoffe fördern. Y1 - 2019 SN - 978-3-96144-098-6 SP - 9 PB - DVS Media GmbH CY - Düsseldorf ER - TY - GEN A1 - Kehm, Christian A1 - Wasilewski, Eric A1 - Miah, Kamal Uddin Mohammad A1 - Ossenbrink, Ralf A1 - Seidlitz, Holger T1 - Effects of extended shielding gas coverage on component contour accuracy in Wire Arc Additive Manufacturing T2 - 4th Symposium on Materials and Additive Manufacturing, Additive 2024, 22. - 24. Mai 2024, Book of Abstracts N2 - Producing near-net-shape components with Wire Arc Additive Manufacturing (WAAM) is a challenging task. Compared to laser-based additive manufacturing technologies, WAAM is characterized by a lower contour accuracy with higher surface roughness and more uneven surface profiles. Therefore, the WAAM requires a high degree of post-processing (machining) which reduces economic efficiency and increases material consumption. Therefore, topics such as process optimization with regard to the component contour are increasingly in the focus of research. This study presents the application of an extended shielding gas coverage in the WAAM process of steel to improve part contour accuracy. A specially adapted shielding gas coverage was manufactured with laser powder bed fusion and following used to study the influence on the resulting component contour and properties in comparison to standard shielding gas nozzles. The investigations include the analysis of temperature profiles, shape deviations, hardness and porosity in the component. In addition, process parameters such as gas flow rate and nozzle geometry were varied in order to evaluate their influence on the accuracy of the component contour. The extended shielding gas coverage reduces the average deviation from the target contour significantly by a degree of 49,44%. In addition, the maximum of the occurring deviation height could be decreased by 42,39%. The results show an improvement in the dimensional accuracy of the contour and the surface quality, resulting in higher reproducibility and less post-processing effort. Y1 - 2024 UR - https://acmit.at/wp-content/uploads/2024/08/Additive-2024_Book-of-abstracts.pdf SN - 978-3-88355-440-2 SP - 29 PB - Deutsche Gesellschaft für Materialkunde (DGM) e.V. CY - Bremen, Berlin ER - TY - GEN A1 - Wasilewski, Eric ED - Gluschkowa, Diana Borysiwna ED - Dosschetschkina, Iryna Wasyliwna ED - Lalasarowa, Natalija Oleksijiwna T1 - Force Control Strategies to reduce Weld Distortion and Cold Cracking in Laser Beam Welding T2 - International Conference of Students and Young Scientists: "Modern Materials and Their Processing Technologies" N2 - In recent years, lightweight construction and the demand for resource and energy efficiency have increasingly supported the use of high-strength steels. Laser beam welding (LBW) of these materials is used in industrial mass production to efficiently manufacture high-precise components and parts with the highest quality requirements. Avoiding welding-related defects such as weld distortion and cold cracking is critical. Conventional applications currently meet this requirement to a limited extent due to very restricted process tolerances and the use of non-critical materials, which limits the potential of the joining process. Based on FE welding process simulations, concepts have been developed to reduce distortion and cracking through active control of the LBW process. The underlying models consider the weld induced temperature field, microstructure transformations, and residual stresses to calculate distortion. In addition, the local hydrogen concentration is calculated, and the results of the welding process simulation are evaluated using a cold cracking tool that includes material-specific cracking criteria. The ability to simulate distortion and cold cracking behavior opens up the possibility of parameter variation. From the data collected, concepts of active force introduction with dynamic workpiece clamping have been derived that lead to distortion and cold cracking reduction and promote the weldability of high-strength materials. KW - laser beam welding KW - high-strength steel KW - cold-cracking KW - finite element welding simulations Y1 - 2023 UR - https://www.researchgate.net/publication/370944206 SP - 6 EP - 16 CY - Charkow, Ukraine ER - TY - GEN A1 - Wasilewski, Eric A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Investigations on the thermal conditions during laser beam welding of high-strength steel 100Cr6 T2 - Advances in Industrial and Manufacturing Engineering N2 - This study examines the thermal conditions during laser beam welding of 100Cr6 high-strength steel using a TruDisk5000 disc laser with a continuous adjustable power range of 100–5000 W. Two parameter sets, characterized by laser power and welding speeds, were analyzed by thermal-metallurgical FE simulations to determine their impact on the thermal conditions during welding. The results show a significant shift in heat coupling, with conduction transitioning to deep penetration welding. As a result of the high welding speeds and reduced energy input, extremely high heating rates up to 2∙104 K s−1 (set A) respectively 4∙105 K s−1 (set B) occur. Both welds thus concern a range of temperature state values for which conventional Time-Temperature-Austenitization (TTA) diagrams are currently not defined, requiring calibration of the material models through general assumptions. Also, the change in energy input and welding speed causes significantly steep temperature gradients with a slope of approximately 5∙103 K mm−1 and strong drops in the temperature rates, particularly in the heat affected zone. The temperature cycles also show very different cooling rates for the respective parameter sets, although in both cases they are well below a cooling time t8/5 of 1 s, so that the phase transformation always leads to the formation of martensite. Since the investigated parameters are known to cause a loss of technological strength and conditionally result in cold cracks, these results will be used for further detailed experimental and numerical investigation of microstructure, hydrogen distribution, and stress-strain development at different restraint conditions. KW - laser beam welding KW - welding temperature field KW - temperature rates KW - thermal-metallurgical FE simulation KW - high-strength steel Y1 - 2023 UR - https://www.sciencedirect.com/science/article/pii/S2666912923000077 U6 - https://doi.org/10.1016/j.aime.2023.100118 SN - 2666-9129 VL - 6 ER -