@misc{EvdokimovJasiewiczDoynovetal., author = {Evdokimov, Anton and Jasiewicz, Filip and Doynov, Nikolay and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Simulation of surface heat treatment with inclined laser beam}, series = {Journal of Manufacturing Processes}, volume = {81}, journal = {Journal of Manufacturing Processes}, issn = {1526-6125}, doi = {10.1016/j.jmapro.2022.06.051}, pages = {107 -- 114}, abstract = {The beam inclination leads to a change in the laser spot size on the material surface. The higher the inclination, the larger the irradiated area and the lower the laser intensity. Moreover, if the material surface is outside of the beam focal plane, the intensity distribution profile becomes asymmetric. In this study, a heat source model, which calculates the intensity distribution on the workpiece surface as a function of beam parameters (beam waist, divergence half-angle) and process parameters (laser power, incidence angle, and distance to focal plane) was developed. The applicability of the heat source model was demonstrated by simulating 4 different laser hardening regimes. Once the heat efficiency coefficient had been calibrated the developed finite-element model allowed computation of temperatures while hardening with perpendicular laser beams as well as with inclined beams. The open-source software FEniCSx was used for the finite element computations. The mathematical formulation, required for performing temperature simulations with FEniCSx was briefly introduced.}, language = {en} } @misc{ShapovalovSeidlitzOstetal., author = {Shapovalov, Oleg and Seidlitz, Holger and Ost, Lucas and Doynov, Nikolay and Kuke, Felix and Ambrosio, Marcello and Michailov, Vesselin}, title = {Substitution von metallischen Schubfeldern im Fahrzeugbau durch f{\"u}getechnische Integration von FKV-Schalen}, series = {DVS Congress 2022, Große Schweißtechnische Tagung, DVS Campus ; Kurzfassungen der Vortr{\"a}ge der Veranstaltung in Koblenz vom 19. bis 21. September 2022 ; (Langfassungen der Beitr{\"a}ge auf USB-Karte)}, journal = {DVS Congress 2022, Große Schweißtechnische Tagung, DVS Campus ; Kurzfassungen der Vortr{\"a}ge der Veranstaltung in Koblenz vom 19. bis 21. September 2022 ; (Langfassungen der Beitr{\"a}ge auf USB-Karte)}, publisher = {DVS Media GmbH}, address = {D{\"u}sseldorf}, isbn = {978-3-96144-189-1}, pages = {385 -- 393}, abstract = {Durch den strukturellen Einsatz von Faser-Kunststoff-Verbunden (FKV) lassen sich hochwertige gewichtsoptimierte Karosserien in Mischbauweise umsetzen. Die untersuchte CMT-Pin-Schweißtechnik zur Verbindung von thermoplastischen Organoblechen mit St{\"a}hlen bietet, im Vergleich zu anderen Verfahren, neben einer einseitigen Zug{\"a}nglichkeit, ein hohes Leichtbaupotenzial. Das Vorhaben wurde auf eine werkstoff-, prozess- und konstruktionsgerechte Umsetzung des Verfahrens ausgerichtet. Auf Basis experimenteller und numerischer Untersuchungen wurde eine Methode zum Vorw{\"a}rmen von Organoblechen mittels Infrarotstrahlung entwickelt. Die Eignung der CMT-Pin-Technologie wurde sowohl f{\"u}r das F{\"u}gen von karbon- als auch glasfaserverst{\"a}rktem PA6 betrachtet. Als Bewertungskriterien wurden das Schweißgut sowie der Faser- und Matrixerhalt in Abh{\"a}ngigkeit der Schweißparameter untersucht. Das entwickelte Verfahren wurde mit herk{\"o}mmlichen F{\"u}gemethoden bzgl. der in Kopf- und Scherzugversuchen ermittelten Festigkeiten verglichen. Zur Bestimmung der Best{\"a}ndigkeit der Verbindungen gegen unterschiedliche Witterungsbedingungen wurden Salzspr{\"u}hnebel- und Wechselkorrosionstests durchgef{\"u}hrt. Mit dem F{\"u}gen von Hutprofilen wurde die Anwendung der entwickelte CMT-Pin-Technik am Tunnel sowie den L{\"a}ngs- und Quertr{\"a}gern der Bodenstruktur eines Kraftfahrzeugs demonstriert.}, language = {de} } @misc{MorozovaKehmObrosovetal., author = {Morozova, Iuliia and Kehm, Christian and Obrosov, Aleksei and Yang, Yitong and Miah, Kamal Uddin Mohammad and Uludintceva, Elena and Fritzsche, Sebastian and Weiß, Sabine and Michailov, Vesselin}, title = {On the Heat Treatment of Selective-Laser-Melted 316L}, series = {Journal of Materials Engineering and Performance}, volume = {32 (2023)}, journal = {Journal of Materials Engineering and Performance}, number = {10}, issn = {1544-1024}, doi = {10.1007/s11665-022-07404-0}, pages = {4295 -- 4305}, abstract = {The effect of heat treatment at various temperatures (650, 850, 1050, and 1100°C) and dwell times (10 min and 1 h) on the metallurgical and microstructural evolution as well as on the related tensile properties of stainless steel 316L processed by selective laser melting (SLM) has been systematically evaluated. The metallurgical and microstructural features such as defects, stability of the columnar-cellular structure and substructure, second phase particles, and phase transformation imparted by SLM and heat treatment have been discussed. It has been shown that the processing conditions specific to SLM significantly alter the kinetics of phase evolution compared to standard welding techniques which affects the accuracy of the prediction. The influence of these characteristics on tensile properties and hardness was elucidated. It was disclosed that with increasing heat treatment temperature there was a gradual increase in elongation but a decrease in strength related to the dislocation density and the development of the microstructure.}, language = {en} } @misc{MorozovaKrolickaObrosovetal., author = {Morozova, Iuliia and Kr{\´o}licka, Aleksandra and Obrosov, Aleksei and Yang, Yitong and Doynov, Nikolay and Weiß, Sabine and Michailov, Vesselin}, title = {Precipitation phenomena in impulse friction stir welded 2024 aluminium alloy}, series = {Materials Science and Engineering: A}, journal = {Materials Science and Engineering: A}, issn = {0921-5093}, doi = {10.1016/j.msea.2022.143617}, pages = {1 -- 11}, abstract = {Microhardness variations across the friction stir welded (FSW) and impulse friction stir welded (IFSW) AA2024-T351 joints have been elucidated by the transformations of the S-Al2CuMg phase with a special focus on a distinguished hardness peak within the heat-affected zone (HAZ) of the impulse welds. The increase in hardness within the stir zone (SZ) originated from the partial re-precipitation of the initial Guinier-Preston-Bagaryatsky zones (GPB) and metastable S needles, previously dissolved.) Formation and growth of stable S precipitates via coalescence accounted for the softening through the thermo-mechanically affected zone (TMAZ). The peak strengthening within the HAZ of the IFSW joints was mainly caused by the dense needle-shaped S particles, which can be explained by a mutual influence of the process specific temperature and strain cycles. Dislocations and subgrain boundaries introduced to the material due to plastic deformation facilitated the nucleation of strengthening S precipitates in the HAZ. It demonstrates that the impact of deformation should be considered by the characterization of the precipitation development in the HAZ.}, language = {en} } @misc{HantelmannFritzscheMichailovetal., author = {Hantelmann, Cord and Fritzsche, Sebastian and Michailov, Vesselin and Boywitt, Ralf}, title = {Entwicklung geschweißter Konstruktionen aus Aluminiumsandwich}, series = {DVS Congress 2022, Große Schweißtechnische Tagung, DVS Campus ; Kurzfassungen der Vortr{\"a}ge der Veranstaltung in Koblenz vom 19. bis 21. September 2022 ; (Langfassungen der Beitr{\"a}ge auf USB-Karte)}, journal = {DVS Congress 2022, Große Schweißtechnische Tagung, DVS Campus ; Kurzfassungen der Vortr{\"a}ge der Veranstaltung in Koblenz vom 19. bis 21. September 2022 ; (Langfassungen der Beitr{\"a}ge auf USB-Karte)}, publisher = {DVS Media GmbH}, address = {D{\"u}sseldorf}, isbn = {978-3-96144-189-1}, pages = {245 -- 251}, abstract = {Im vorgestellten Projekt wurden werkstoff- und konstruktionsgerechte Knotenformen aus Aluminiumschaumsandwich gestaltet und mit unterschiedlichen Schweißverfahren, wie dem Metall-Inertgas-Schweißen und dem R{\"u}hrreibschweißen, gef{\"u}gt und gepr{\"u}ft. In umfangreichen Untersuchungen wurden die Knoten, der Sandwichverbund und die Einzelkomponenten des Sandwich, Schaum und Decklagen, anhand der statischen Festigkeit und Schwingfestigkeit bewertet. Zus{\"a}tzlich wurden innere Sch{\"a}digungsmechanismen betrachtet. Mit experimentellen und numerischen Nachweismethoden konnte die anwendungssichere Knotengestaltung, -anbindung und -berechnung der unterschiedlichen Verbindungstypen umgesetzt werden. Die Ergebnisse wurden im Rahmen der Nachweisf{\"u}hrung gegen{\"u}bergestellt und hinsichtlich eines praxisgerechten Einsatzes nach FKM-Richtlinie bzw. Eurocode9 bewertet. Mit den ermittelten Ergebnissen wurde die bisherige Gestaltungs- und F{\"u}gerichtlinie um neue Verbindungstypen erweitert.}, language = {de} } @misc{KotlarskiOrmanovaOssenbrinketal., author = {Kotlarski, Georgi and Ormanova, Maria and Ossenbrink, Ralf and Nikitin, Alexander and Doynov, Nikolay and Valkov, Stefan and Michailov, Vesselin}, title = {Fabrication and Characterization of Wire Arc Additively Manufactured AlSi5 Structures}, series = {Metals}, volume = {12}, journal = {Metals}, number = {11}, issn = {2075-4701}, abstract = {For the purpose of this research, single track details were manufactured in the shape of thin walls with a length of 100 mm and a height of 80 mm. Two welding speeds were chosen for this experiment-13.3 mm/s and 20.0 mm/s corresponding to the following heat inputs: 120 J/mm and 80 J/mm. The gas metal arc welding (GMAW) method was used for the build-up of the specimens in the cold arc pulse mode. The structure of the specimens was studied using X-ray diffraction (XRD) analysis carried out with CuKα radiation with a wavelength of 1.5406 Ǻ, optical microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). Furthermore, the Vickers hardness of the samples was determined using a ZwickRoell DuraScan 10/20 G5 unit at a force of 1 N. A preferred crystallographic orientation towards the (200) plane was observed in all cases, however a vastly textured structure was observed with inclusions of peaks in the (111), (220), and (311) crystallographic planes. The full width at half maximum (FWHM) of samples taken from different stages of build-up was calculated indicating an increase of the dislocation density at the more advanced stages of specimen growth. Despite that an increase of the hardness was observed towards the top of both specimens. This is attributed to the change in the structure of the αAl + Si formations from an irregular one at the bottom of the specimens, towards a fibrous one at the top. The results are discussed in regard to the optimization of the build-up process during wire arc additive manufacturing (WAAM).}, language = {en} } @misc{MiahKloshekGonzalezCastanoetal., author = {Miah, Kamal Uddin Mohammad and Kloshek, Alexander and Gonz{\´a}lez-Casta{\~n}o, Miriam and Kehm, Christian and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Herstellen hocheffektiver Mikroreaktoren durch selektives Laserstrahlschmelzen}, series = {DVS Congress 2022, Große Schweißtechnische Tagung, DVS Campus ; Kurzfassungen der Vortr{\"a}ge der Veranstaltung in Koblenz vom 19. bis 21. September 2022 ; (Langfassungen der Beitr{\"a}ge auf USB-Karte)}, journal = {DVS Congress 2022, Große Schweißtechnische Tagung, DVS Campus ; Kurzfassungen der Vortr{\"a}ge der Veranstaltung in Koblenz vom 19. bis 21. September 2022 ; (Langfassungen der Beitr{\"a}ge auf USB-Karte)}, publisher = {DVS Media GmbH}, address = {D{\"u}sseldorf}, isbn = {978-3-96144-189-1}, pages = {708 -- 713}, abstract = {Das pulverbasierte 3D-Metalldrucken erm{\"o}glicht die Fertigung von hochkomplexen Integralbauteilen, die als Tr{\"a}gerstruktur f{\"u}r Mikroreaktoren benutzt werden. Nach einer Beschichtung der Struktur mit einem Katalysatormaterial, k{\"o}nnen diese Mikroreaktoren h{\"o}chst effizient f{\"u}r die CO2-Methanisierung eingesetzt werden. Durch die additive Fertigung mit dem selektiven Laserstrahlschmelzen (SLM) wurden adaptierte dreidimensionale periodische Gitterstrukturen mit sehr geringen Wandst{\"a}rken hergestellt. Diese weisen ein sehr g{\"u}nstiges Verh{\"a}ltnis von Oberfl{\"a}che zu Volumen (TPMS - Triply periodic minimal surface) auf. Des Weiteren zeigen die TPMS-Strukturen vorteilhafte Str{\"o}mungseigenschaften, die sowohl f{\"u}r die Beschichtung mit dem Katalysator-Material als auch die Durchstr{\"o}mung mit den Reaktionsmedien im Betrieb essentiell sind. So ist es beispielsweise m{\"o}glich, durch die Variation der Dimension einer TPMS-Struktur die Oberfl{\"a}che pro Volumeneinheit, den hydraulischen Durchmesser des Reaktors und somit auch den Transportprozess des Fluids deutlich zu verbessern. Diese Faktoren erm{\"o}glichen eine effektivere Gas-Katalysator-Reaktion. Im Vergleich zu Mikroreaktorstrukturen aus den traditionellen Herstellungsverfahren liefern die additiv gefertigten Strukturen sowohl eine h{\"o}here CO2-Umwandlungsrate als auch eine CH4-Selektivit{\"a}t innerhalb des diffusionskontrollierten Bereichs.}, language = {de} } @misc{KotlarskiOrmanovaNikitinetal., author = {Kotlarski, Georgi and Ormanova, Maria and Nikitin, Alexander and Morozova, Iuliia and Ossenbrink, Ralf and Michailov, Vesselin and Doynov, Nikolay and Valkov, Stefan}, title = {Structure Formation and Mechanical Properties of Wire Arc Additively Manufactured Al4043 (AlSi5) Components}, series = {Metals}, volume = {14}, journal = {Metals}, number = {2}, issn = {2075-4701}, doi = {10.3390/met14020183}, abstract = {In the current paper, the correlation between the physical size of additively built wire arc specimens and their structure and properties is studied. For the purpose of this work, two oval shaped specimens of different lengths were manufactured under the same technological conditions. The specimens have a length of 200 mm and 400 mm and will be referred to as L200 and L400. The microstructure of the samples was studied using X-ray diffraction analysis (XRD), optical microscopy, and scanning electron microscopy (SEM). The microhardness, yield strength (YS), and ultimate tensile strength (UTS) were determined and their correlation with the technological conditions of specimen build-up was clarified. The results of the carried out experiments indicated that the crystallographic structure of both specimens is similar. The scanning electron microscopy images show a higher concentration of irregularly shaped micro-pores formed near the edge of the αAl grains in the structure of the L400 specimen compared to the L200 one. An increase in the size of the αAl solid solution grains in the case of the L200 specimen towards its top section was noticed using optical microscopy. A slightly lower magnitude change was noticed concerning the L400 specimen. The increase in the size of the aluminum crystals was determined to be the increasing interpass temperature. Due to the much smaller thermal dissipation capacity of the smaller specimen, the interpass temperature of the same increased faster compared to the larger specimen. All of the above-mentioned factors led to a decrease in the microhardness of the specimens at higher stages of build-up. Since the specimens were deposited using similar layer deposition conditions, the resultant YS and UTS data are also highly comparable.}, language = {en} } @misc{MiahKloshekOssenbrinketal., author = {Miah, Kamal Uddin Mohammad and Kloshek, Alexander and Ossenbrink, Ralf and Seidlitz, Holger}, title = {Selective Laser Melting of Pure Copper (Cu-ETP)}, series = {4th Symposium on Materials and Additive Manufacturing, Additive 2024, 22. - 24. Mai 2024, Book of Abstracts}, journal = {4th Symposium on Materials and Additive Manufacturing, Additive 2024, 22. - 24. Mai 2024, Book of Abstracts}, publisher = {Deutsche Gesellschaft f{\"u}r Materialkunde (DGM) e.V.}, address = {Bremen, Berlin}, isbn = {978-3-88355-440-2}, pages = {19}, abstract = {The main objective of this study is to address the difficulties related to the production of highly dense parts utilizing pure Cu-ETP powder. In order to achieve this goal, the SLM machine was modified by replacing the regular infrared laser with a laser operating in the range of 530 to 534 nm. Following this modification, a detailed experiment was conducted to determine the most effective procedural parameters for producing solid components and gyroid structures of Cu-ETP. The study determined thtat in order to produce a part density of 99.6 ± 0.2\%, the following parameters are required: a laser power of 130 ± 10 W, a scanning speed of 350 mm/s, and a layer thickness of 25 µm. The microscopic analysis on the SLM-manufactured components showed a consistent grain structure across the build parts. Furthermore, it was discovered that exceeding the predetermined laser power and scanning speed parameters led to lower density of the parts. Conversely, decreasing the laser power and scanning speed below these thresholds was determined to be economically disadvantageous.}, language = {en} } @misc{KehmWasilewskiMiahetal., author = {Kehm, Christian and Wasilewski, Eric and Miah, Kamal Uddin Mohammad and Ossenbrink, Ralf and Seidlitz, Holger}, title = {Effects of extended shielding gas coverage on component contour accuracy in Wire Arc Additive Manufacturing}, series = {4th Symposium on Materials and Additive Manufacturing, Additive 2024, 22. - 24. Mai 2024, Book of Abstracts}, journal = {4th Symposium on Materials and Additive Manufacturing, Additive 2024, 22. - 24. Mai 2024, Book of Abstracts}, publisher = {Deutsche Gesellschaft f{\"u}r Materialkunde (DGM) e.V.}, address = {Bremen, Berlin}, isbn = {978-3-88355-440-2}, pages = {29}, abstract = {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.}, language = {en} } @misc{NikitinTurabovErmilovaetal., author = {Nikitin, Alexander and Turabov, Dashqin and Ermilova, Evgeniia and Evdokimov, Anton and Ossenbrink, Ralf and Seidlitz, Holger}, title = {Using dynamic resistance to predict electrode surface degradation in resistance spot welding of 5182 aluminum alloy}, series = {Welding in the World}, volume = {69}, journal = {Welding in the World}, doi = {10.1007/s40194-024-01872-9}, pages = {449 -- 458}, abstract = {In this study, the correlation between dynamic resistance during the first 10 ms of welding time and the electrode surface condition in resistance spot welding of 5182 aluminum alloy has been investigated. The electrode surface rapidly degrades due to contamination and morphological changes, adversely affecting the weld spot surface. The accumulation of Cu-Al intermetallic phases on the electrode surface alters its roughness, leading to variations in dynamic resistance. By analyzing this correlation, optimal electrode milling intervals were identified to extend electrode life. This work focused on detecting crater formation on the electrode surface through dynamic resistance monitoring. The results indicate that resistance measurements provide a reliable approach for evaluating electrode wear, optimizing maintenance schedules, and reducing material removal during milling.}, language = {en} } @misc{OrmanovaKotlarskiKaishevaetal., author = {Ormanova, Maria and Kotlarski, Georgi and Kaisheva, Darina and Nikitin, Alexander and Ossenbrink, Ralf and Doynov, Nikolay and Valkov, Stefan}, title = {Investigation of the thermal gradients formed during the process of cooling of WAAM built Al99.7 specimen}, series = {Journal of Physics: Conference Series}, volume = {2024}, journal = {Journal of Physics: Conference Series}, number = {2710}, issn = {1742-6596}, doi = {10.1088/1742-6596/2710/1/012038}, abstract = {This work presents a preliminary experiment used to determine the possibility of developing a thermal model used to predict the thermal gradients formed during the process of wire and arc additive manufacturing (WAAM). For this purpose, an Al99.7 specimen was built using gas metal arc welding (GMAW) in the cold arc pulse mode. The temperature of both the substrate and each consecutive layer was measured using thermocouples and infrared thermometers and the experimental data was used for the calibration of the developed thermal model. The obtained results can be used for the further development of the thermal model.}, language = {en} } @misc{KotlarskiOrmanovaNikitinetal., author = {Kotlarski, Georgi and Ormanova, Maria and Nikitin, Alexander and Ossenbrink, Ralf and Doynov, Nikolay and Valkov, Stefan and Michailov, Vesselin}, title = {Structure, morphology and hardness of a WAAM built Al99.7 specimen}, series = {International Scientific Conference Unitech 2023, Gabrovo : selected papers}, volume = {2}, journal = {International Scientific Conference Unitech 2023, Gabrovo : selected papers}, editor = {Tsankov, Plamen and Maximov, Jordan and Aleksandrov, Anatoliy and Todorov, Todor and Peneva, Petya}, publisher = {Union of Automation \& Informatics}, address = {Gabrovo}, issn = {1313-230X}, doi = {10.70456/PJKY7011}, pages = {349 -- 353}, abstract = {The present work discusses the possibility of wire arc additive manufacturing (WAAM) of pure aluminum specimens (Al99.7). The manufactured specimen's structure was studied using X-ray diffraction (XRD) experiments. The morphology of the specimen at different stages of build-up was studied by examining prepared mechanical properties of the specimen, and for this reason the microhardness of the specimen was studied as well. The results of the present study were discussed regarding the change of the structure of the samples with the increase of the specimen's height during the manufacturing process and its influence on the resultant microhardness.}, language = {en} } @misc{BergDueckershoffHertrampfetal., author = {Berg, Heinz Peter and D{\"u}ckershoff, Roland and Hertrampf, Stefan and Kloshek, Alexander and Himmelberg, Axel}, title = {Development of an injector spark plug for the injection and ignition of gaseous fuels in internal combustion engines for use in conventional systems}, series = {AIP Conference Proceedings}, volume = {3626 (2024)}, journal = {AIP Conference Proceedings}, publisher = {AIP Publishing}, address = {Chiang Mai}, doi = {10.1063/5.0238165}, pages = {1 -- 8}, abstract = {An injection-ignition-system from an additive manufacturing process is presented with which gaseous fuels can be injected into the combustion chamber of an internal combustion engine under pressures of up to 80 bar and ignited. With the presented system, an improvement of the thermal efficiency can be achieved by a late fuel injection in the compression phase and with post-injection. With such a system, the engine becomes purely air-intake and a better filling level is achieved. Injection and ignition can take place simultaneously with this application. The system is designed with a high pressure stability for all components (200 bar) and can therefore also be used with higher compressions and combustion pressures. The spatial distribution of the fuel in the combustion chamber is achieved by angled fluid ports and also allows additional injections and ignitions in the power stroke and in the relief phase. This can improve thermal efficiency. A built-in annular channel also enables two different fuels to be injected as a mixing chamber. Finally, initial measurement results are shown for the use of hydrogen fuel in a single-cylinder engine. Indexing data and performance data of the engine indicate that the system can represent a significant increase in the efficiency of combustion engines with hydrogen fuel. Furthermore, the system can be used in conventional vehicle systems, whereby only fuel conditioning and control systems need to be adapted.}, language = {en} } @misc{FlorianSchrickerZenzetal., author = {Florian, Tobias and Schricker, Klaus and Zenz, Constantin and Otto, Andreas and Schmidt, Leander and Diegel, Christian and Friedmann, Hannes and Seibold, Marc and Hellwig, Peter and Fr{\"o}hlich, Fabian and Nagel, Falk and Kallage, Peter and Buttazzoni, Michele and Rack, Alexander and Requardt, Herwig and Chen, Yunhui and Bergmann, Jean Pierre}, title = {Combining in situ synchrotron X-ray imaging and multiphysics simulation to reveal pore formation dynamics in laser welding of copper}, series = {International Journal of Machine Tools and Manufacture}, volume = {204}, journal = {International Journal of Machine Tools and Manufacture}, publisher = {Elsevier BV}, issn = {0890-6955}, doi = {10.1016/j.ijmachtools.2024.104224}, pages = {1 -- 22}, abstract = {Laser beam welding has emerged as a powerful tool for manufacturing copper components in electrical vehicles, electronic devices or energy storage, owing to its rapid processing capabilities. Nonetheless, the material's high thermal conductivity and low absorption of infrared light can introduce process instabilities, resulting in defects such as pores. This study employs a hybrid approach that combines in situ synchrotron X-ray imaging with compressible multiphysics process simulation to elucidate pore-forming mechanisms during laser beam welding of copper. High-speed synchrotron X-ray imaging with an acquisition rate of 20,000 images/second facilitates the identification of relevant process regimes concerning pore formation during laser beam welding of copper with a wavelength of 1070 nm. Furthermore, in situ observations with high temporal and spatial resolution present a unique database for extensive validation of a multi-physics process simulation based on welding processes using different concentric intensity distributions. These validated simulation results enable thorough comprehension of process-related pore formation based on the interaction between keyhole, melt pool and resulting flow field. The findings show that pore formation is driven by four different mechanisms: bulging, spiking, upwelling waves at the keyhole rear wall and melt pool ejections. The synergy of high- speed synchrotron X-ray imaging and multi-physics modeling provides a fundamental understanding of the chronological sequence of events leading to process-related pore formation during laser beam welding of copper.}, language = {en} } @misc{KoehlerNikitinSonnenfeldetal., author = {K{\"o}hler, Marcel and Nikitin, Alexander and Sonnenfeld, Peter and Ossenbrink, Ralf and J{\"u}ttner, Sven}, title = {Wire arc additive manufacturing of aluminum foams using TiH2-Laced Welding Wires}, series = {Materials}, volume = {17}, journal = {Materials}, number = {13}, publisher = {MDPI AG}, issn = {1996-1944}, doi = {10.3390/ma17133176}, abstract = {Composite materials made from aluminum foam are increasingly used in aerospace and automotive industries due to their low density, high energy absorption capacity, and corrosion resistance. Additive manufacturing processes offer several advantages over conventional manufacturing methods, such as the ability to produce significantly more geometrically complex components without the need for expensive tooling. Direct Energy Deposition processes like Wire Arc Additive Manufacturing (WAAM) enable the additive production of near-net-shape components at high build rates. This paper presents a technology for producing aluminum foam structures using WAAM. This paper's focus is on the development of welding wires that are mixed with a foaming agent (TiH2) and produce a foamed weld metal as well as their processing using MIG welding technology.}, language = {en} } @incollection{HantelmannFritzscheMichailovetal., author = {Hantelmann, Cord and Fritzsche, Sebastian and Michailov, Vesselin and Boywitt, Ralf and Risse, Steffen and P{\"o}ge, Matthias and Vogelsang, J{\"o}rg and Cramer, Heidi}, title = {Geschweißte Konstruktionen aus Aluminiumschaumsandwich}, series = {Jahrbuch Schweisstechnik 2025 : ein Leitfaden durch die Branche der F{\"u}ge-, Trenn- und Beschichtungstechnik}, booktitle = {Jahrbuch Schweisstechnik 2025 : ein Leitfaden durch die Branche der F{\"u}ge-, Trenn- und Beschichtungstechnik}, publisher = {DVS Media}, address = {D{\"u}sseldorf}, isbn = {978-3-96144-271-3}, pages = {356 -- 370}, abstract = {Im vorgestellten Projekt wurden werkstoff- und konstruktionsgerechte Knotenformen aus Aluminiumschaumsandwich (engl. Aluminium Foam Sandwich, AFS) gestaltet und mit unterschiedlichen Schweißverfahren wie dem Metall-Inertgasschweißen und dem R{\"u}hrreibschweißen gef{\"u}gt sowie gepr{\"u}ft. Im Rahmen der Arbeiten stand dabei die schweißtechnische Verarbeitung von AFS mit anderen Produkten, wie den Strangpressprofilen oder dem Aluminiumvollmaterial, und deren Beanspruchbarkeit im Vordergrund. In umfangreichen Untersuchungen wurden hierzu sowohl die Verbindungsknoten selbst als auch der Sandwichverbund und die Einzelkomponenten des Sandwich, Schaum und Decklagen, anhand der statischen Festigkeit und Schwingfestigkeit bewertet. Zus{\"a}tzlich wurden innere Sch{\"a}digungsmechanismen betrachtet. Mit experimentellen und numerischen Nachweismethoden konnte die anwendungssichere Knotengestaltung, -anbindung und -berechnung der unterschiedlichen Verbindungstypen umgesetzt werden. Die Ergebnisse wurden im Rahmen der Nachweisf{\"u}hrung gegen{\"u}bergestellt und hinsichtlich eines praxisgerechten Einsatzes nach FKM-Richtlinie bzw. Eurocode9 bewertet. Mit den ermittelten Ergebnissen wurde die bisherige Gestaltungs- und F{\"u}gerichtlinie um neue Verbindungstypen erweitert}, language = {de} } @misc{SeidlitzOstAmbrosioetal., author = {Seidlitz, Holger and Ost, Lucas and Ambrosio, Marcello and Kuke, Felix and Michailov, Vesselin and Shapovalov, Oleg and Doynov, Nikolay}, title = {Erw{\"a}rmung von Composites simulieren}, series = {Kunststoffe}, journal = {Kunststoffe}, number = {2}, issn = {0023-5563}, pages = {66 -- 70}, abstract = {Neuartige, werkstoffgerechte F{\"u}geverfahren f{\"u}r Faserkunststoffverbunde setzen die Erw{\"a}rmung der Materialien voraus. Um die damit verbundenen komplexen Temperaturfelder und -verl{\"a}ufe vorherzusagen, haben das Fraunhofer IAP und die BTU Cottbus-Senftenberg numerische Verfahren entwickelt. Mit diesen k{\"o}nnen auch verschiedene Strahlungsquellen und Prozessabl{\"a}ufe simuliert werden.}, language = {de} } @misc{HagenKlinkenbergOssenbrinketal., author = {Hagen, Christian and Klinkenberg, Franz-Josef and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Resistance spot welding of dissimilar material joints with a cold-gas-sprayed inlayer}, series = {The International Journal of Advanced Manufacturing Technology}, journal = {The International Journal of Advanced Manufacturing Technology}, issn = {1433-3015}, doi = {10.1007/s00170-023-11897-x}, pages = {12}, abstract = {In this publication, cold gas spraying (CGS) is investigated as an enabler for aluminum-steel joints. Using a powder-based coating process to adhere a steel layer to an aluminum substrate allows a steel component to be welded to the deposited layer by resistance spot welding. This method permits the metallurgical connection between similar materials to be separated, while mechanical bonding ensures the connection at the dissimilar aluminum-to-inlayer interface. A modification of the porous CGS layer, as well as the creation of the remelted zone in the aluminum, can be observed during the resistance spot welding process. Electron backscatter diffraction (EBSD) analyses show that the severely prestressed particles in the CGS coating recrystallize, which coincides with a decrease in defect density and hardness in the heat-affected zone. Microscopy of the aluminum substrate shows the creation of metallurgical pores as well as the expansion of pores attributed to the casting process. The rise in remelted aluminum hardness and decrease in the heat-affected zone of the CGS layer indicate the formation of a metallurgical notch.}, language = {en} } @misc{ShapovalovOstKukeetal., author = {Shapovalov, Oleg and Ost, Lucas and Kuke, Felix and Doynov, Nikolay and Ambrosio, Marcello and Seidlitz, Holger and Michailov, Vesselin}, title = {Entwicklung und Analyse einer F{\"u}gestrategie f{\"u}r FKV/Metall-Mischverbindungen auf Basis der CMT-Pinschweißtechnik}, series = {Joining Plastics}, volume = {17}, journal = {Joining Plastics}, number = {1}, issn = {1864-3450}, pages = {28 -- 35}, abstract = {Dieser Beitrag stellt eine Entwicklung, Anpassung und Untersuchung der neuartigen Pinschweißtechnik zur Verbindung thermoplastischer Faserkunststoffverbunde mit metallischen F{\"u}gepartnern dar. Die untersuchte F{\"u}getechnik bietet, im Vergleich zu anderen Verfahren, neben einer einseitigen Zug{\"a}nglichkeit, ein hohes Leichtbaupotenzial. An Multimaterial-Einzelpinverbindungen wurden die CMT-Pinschweißbarkeit charakterisiert und unterschiedliche F{\"u}gestrategien erprobt und ausgewertet. Als Bewertungskriterien wurden das Schweißgut sowie der Faser- und Matrixerhalt in Abh{\"a}ngigkeit von den Schweißparametern untersucht. Die mechanische Beanspruchbarkeit der mit dem entwickelten Verfahren erstellten Verbindungen wurde in Scherzugversuchen ermittelt. An Mehrpinverbindungen wurde anschließend der Einfluss der Pinanordnung untersucht und die Auslegung der F{\"u}gezone analysiert. Der F{\"u}geprozess wurde an Funktionsmustern und diese wiederum in 3-Punkt-Biegeversuchen validiert sowie mit dem Kleben verglichen.}, language = {de} } @misc{SeidlitzMichailovOstetal., author = {Seidlitz, Holger and Michailov, Vesselin and Ost, Lucas and Kuke, Felix and Ambrosio, Marcello and Shapovalov, Oleg and Doynov, Nikolay}, title = {Simulation of Composites' Heating}, series = {Kunststoffe international}, volume = {113}, journal = {Kunststoffe international}, number = {4}, issn = {1862-4243}, pages = {60 -- 64}, abstract = {Modern material-compatible joining methods for fiber-reinforced plastics require the heating of the materials. In order to predict the respective complex temperature fields and curves, the Fraunhofer IAP and the BTU Cottbus-Senftenberg have developed numerical methods, which are able to simulate different radiation sources and process sequences as well.}, language = {en} } @misc{Wasilewski, author = {Wasilewski, Eric}, title = {Force Control Strategies to reduce Weld Distortion and Cold Cracking in Laser Beam Welding}, series = {International Conference of Students and Young Scientists: "Modern Materials and Their Processing Technologies"}, journal = {International Conference of Students and Young Scientists: "Modern Materials and Their Processing Technologies"}, editor = {Gluschkowa, Diana Borysiwna and Dosschetschkina, Iryna Wasyliwna and Lalasarowa, Natalija Oleksijiwna}, address = {Charkow, Ukraine}, pages = {6 -- 16}, abstract = {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.}, language = {en} } @misc{WasilewskiDoynovOssenbrinketal., author = {Wasilewski, Eric and Doynov, Nikolay and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Investigations on the thermal conditions during laser beam welding of high-strength steel 100Cr6}, series = {Advances in Industrial and Manufacturing Engineering}, volume = {6}, journal = {Advances in Industrial and Manufacturing Engineering}, issn = {2666-9129}, doi = {10.1016/j.aime.2023.100118}, abstract = {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.}, language = {en} } @misc{TurabovEvdokimovNikitinetal., author = {Turabov, Dashqin and Evdokimov, Anton and Nikitin, Alexander and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Vorhersage des Elektrodenverschleißes beim Widerstandspunktschweißen von Aluminium durch dynamische Widerstandsmessung}, series = {DVS Congress 2023, Große Schweißtechnische Tagung, DVS Campus ; Kurzfassungen der Vortr{\"a}ge der Veranstaltung in Essen vom 11. bis 14. September 2023 ; (Langfassungen der Beitr{\"a}ge auf USB-Karte)}, volume = {389 / 2023}, journal = {DVS Congress 2023, Große Schweißtechnische Tagung, DVS Campus ; Kurzfassungen der Vortr{\"a}ge der Veranstaltung in Essen vom 11. bis 14. September 2023 ; (Langfassungen der Beitr{\"a}ge auf USB-Karte)}, publisher = {DVS Media GmbH}, address = {D{\"u}sseldorf}, isbn = {978-3-96144-230-0}, pages = {780 -- 787}, abstract = {Das Widerstandspunktschweißen ist ein weit verbreitetes Schweißverfahren, insbesondere bei der Karosserieherstellung in der Automobilbranche. Im Hinblick auf den Leichtbau werden zunehmend Aluminiumlegierungen verwendet. Das Hauptproblem beim Widerstandspunktschweißen von Aluminiumlegierungen ist der schnelle Elektrodenverschleiß. Dadurch wird die Qualit{\"a}t und Effizienz des Schweißprozesses beeintr{\"a}chtigt. Die Elektrodenstandmenge ist erreicht, wenn die Schweißverbindung eines der Qualit{\"a}tskriterien nicht erf{\"u}llt. Um die Elektrodenstandmenge zu ermitteln, werden in der Industrie im Rahmen der Schweißnahtqualifizierung zeit- und ressourcenaufw{\"a}ndige Methoden, u. a. zerst{\"o}rende Pr{\"u}fmethoden, verwendet. In dieser Arbeit wird eine Methode zur Vorhersage des kritischen Elektrodenverschleißes beim Aluminiumschweißen durch Messung des dynamischen Widerstandes vorgeschlagen. In umfangreichen Versuchsreihen an einer automobiltypischen Al-Legierung der 5000er Gruppe wurden dynamische Widerstandsmessungen durchgef{\"u}hrt. Aus den Widerstandsmesswerten konnte ein Indikator ermittelt werden, welcher auf das Auftreten von Poren in Schweißverbindung und auf einen bald auftretenden kritischen Elektrodenverschleiß hinweist.}, language = {de} } @misc{HantelmannFritzscheMichailovetal., author = {Hantelmann, Cord and Fritzsche, Sebastian and Michailov, Vesselin and Boywitt, Ralf and Risse, Steffen and P{\"o}ge, Matthias and Vogelsang, J{\"o}rg and Cramer, Heidi}, title = {Geschweißte Konstruktionen aus Aluminiumschaumsandwich}, series = {Schweißen und Schneiden}, volume = {75}, journal = {Schweißen und Schneiden}, number = {12}, issn = {0036-7184}, pages = {912 -- 922}, abstract = {Im vorgestellten Projekt wurden werkstoff- und konstuktionsgerechte Knotenformen aus Aluminiumschaumsandwich (engl. Aluminium Foam Sandwich, AFS) gestaltet und mit unterschiedlichen Schweißverfahren wie dem Metall-Inertgasschweißen und dem R{\"u}hrreibschweißen gef{\"u}gt und gepr{\"u}ft. Im Rahmen der Arbeiten stand dabei die schweißtechnische Verarbeitung von AFS mit anderen Produkten, wie den Strangpressprofilen oder dem Aluminiumvollmaterial, und deren Beanspruchbarkeit im Vordergrund. In umfangreichen Untersuchungen wurden hierzu sowohl die Verbindugsknoten selbst als auch der Sandwichverbund und die Einzelkomponenten des Sandwich, Schaum und Decklagen, anhand der statischen Festigkeit und Schwingfestigkeit bewertet. Zus{\"a}tzlich wurden innere Sch{\"a}digungsmechanismen betrachtet. Mit experimentellen und numerischen Nachweismethoden konnte die anwendungssichere Knotengestaltung, -anbindung und -berechnung der unterschiedlichen Verbindungstypen umgesetzt werden. Die Ergebnisse wurden im Rahmen der Nachweisf{\"u}hrung gegen{\"u}bergestellt und hinsichtlich eines praxisgerechten Einsatzes nach FKM-Richtlinie bzw. Eurocode9 bewertet. Mit den ermittelten Ergebnissen wurde die bisherige Gestaltungs- und F{\"u}gerichtlinie um neue Verbindungstypen erweitert.}, language = {de} } @misc{KotlarskiOrmanovaNikitinetal., author = {Kotlarski, Georgi and Ormanova, Maria and Nikitin, Alexander and Morozova, Iuliia and Ossenbrink, Ralf and Michailov, Vesselin and Doynov, Nikolay and Valkov, Stefan}, title = {Microstructural and Mechanical Properties of CAP-WAAM Single-Track Al5356 Specimens of Differing Scale}, series = {Materials}, volume = {12}, journal = {Materials}, number = {1}, issn = {2075-1702}, doi = {10.3390/machines12010072}, abstract = {The mass production of metallic components requires high agility in the working process conditioned by the necessity of building details of different shapes and sizes. Changing the size of the components theoretically influences the thermal dissipation capability of the same, which could lead to a change in their structure and mechanical properties. This is particularly important when aluminum alloys are concerned. For this reason, two Al5356 single-track specimens were built using the same technological conditions of layer deposition by varying only their geometrical size. In all cases, the specimens were wire and arc additively manufactured (WAAM) using a process based on gas metal arc welding (GMAW) in the cold arc pulse mode (CAP). The structure of both specimens was studied and defects along their surfaces were detected in the form of micro-pores and micro-cracks. A high concentration of undissolved Mg particles was also detected, along with some standalone Si particles. Uniformity in the build-up process was achieved, which led to the formation of nearly identical structures in the specimens. Subsequently, the resultant mechanical properties were also highly comparable. This indicates that the geometry-related variation in thermal conditions has an insignificant influence on the component's structure and properties.}, language = {en} } @misc{TognoliSchrickerBassolinietal., author = {Tognoli, Emanuele and Schricker, Klaus and Bassolini, Elena and Bergmann, Jean Pierre}, title = {Influence of the eutectic interface on the fatigue behavior of friction stir spot welds of aluminum with copper}, series = {International Journal of Fatigue}, volume = {194}, journal = {International Journal of Fatigue}, number = {May 2025}, publisher = {Elsevier}, issn = {0142-1123}, doi = {10.1016/j.ijfatigue.2025.108834}, abstract = {The development of hybrid bonds between copper and aluminum is being pursued for reasons of cost, functionality, and weight, particularly in the field of electromobility, to achieve near net-zero emissions. Joining aluminum to copper is a challenge, as interfacial intermetallic compounds have a negative impact on the strength, ductility, and electrical properties of the joint. The development of brittle intermetallic compounds can be limited by targeted temperature control, making solid-phase joining processes particularly suitable. In this article, the fatigue behaviour of friction stir spot welded joints of copper CW004A and aluminum alloy AA1050A with probeless tools is studied. A melt film forms between the metals and the axial force displaces this film laterally, creating an intermediate layer of eutectic and Al2Cu in the joint area. The effect of this layer on the fatigue behaviour of the joint was investigated in this study. At high loads, failure occurs by a combination of Modes I and II with crack propagation in as well as around the bonding area, while at low loads only Mode I is observed. Typically, cracks origin at the spot outer diameter in aluminum, propagate at first in the laterally expelled melt and then through the aluminum sheet, causing unbuttoning.}, language = {en} } @incollection{Miah, author = {Miah, Kamal}, title = {Die Sch{\"o}nheit des W{\"a}rmetauschers}, series = {99 Zukunftsobjekte aus der Lausitz}, booktitle = {99 Zukunftsobjekte aus der Lausitz}, publisher = {Ch. Links}, address = {Berlin}, isbn = {978-3-96289-228-9}, pages = {130 -- 131}, language = {de} } @misc{WaltherSchmidtRaethetal., author = {Walther, Dominik and Schmidt, Leander and R{\"a}th, Timo and Schricker, Klaus and Bergmann, Jean Pierre and Sattler, Kai-Uwe and M{\"a}der, Patrick}, title = {Deep learning-driven active sheet positioning using linear actuators in laser beam butt welding of thin steel sheets}, series = {Journal of advanced joining processes}, volume = {11}, journal = {Journal of advanced joining processes}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {2666-3309}, doi = {10.1016/j.jajp.2025.100303}, pages = {1 -- 12}, abstract = {Welding thin steel sheets in industrial applications is difficult because joint gaps occur during the process, which can lead to weld interruptions. Such welds are considered a reject and in order to avoid the weld to interrupt it is crucial to hinder the formation of joint gaps. Especially laser beam welding is affected by the emergence of gaps. Due to the narrow laser spot, product quality is highly dependent on the alignment and positioning of the sheets. This is typically done by clamping devices, which hold the workpieces in place. However, these clamps are suited for a specific workpiece geometry and require manual redesign every time the process changes. Adaptive clamping devices instead are designed to realize a time-dependent workpiece adjustment. Modeling the joint gap behavior to realize a controller for adaptive clamps can be difficult as the influence of heating, melting, and cooling on the joint gap formation is unknown and varies due to temperature dependent physical properties. Instead, the control parameters and actions can be derived using data-driven methods. In this paper, we present a novel data-driven approach how deep learning can be utilized to manipulate the sheet position during the weld with two actuators that apply force. A temporal convolution neural network (TCN) analyzes the change of the joint gap and predicts the required force to adapt the workpiece position. The developed method has been integrated into the welding process and improves the length of the average weld seam by 39.5\% compared to welds without an active adjustment and 1.4\% to welds that have been adapted with a constant force.}, language = {en} } @misc{WaltherSchmidtSchrickeretal., author = {Walther, Dominik and Schmidt, Leander and Schricker, Klaus and Junger, Christina and Bergmann, Jean Pierre and Notni, Gunther and M{\"a}der, Patrick}, title = {Dataset for weld seam analysis and discontinuity prediction in laser beam welding scenarios}, series = {Data in brief}, volume = {59}, journal = {Data in brief}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {2352-3409}, doi = {10.1016/j.dib.2025.111381}, pages = {1 -- 8}, abstract = {Laser beam welding can produce narrow, high-quality welds in various industrial joining processes. The thermal expansion and contraction of the metal during the weld results in the displacement of the sheets. That leads to the formation of joint gaps and subsequent to a process interruption. This behavior has only been analyzed to a limited extent and causes manufacturers to rely on heavy clamping systems rather than using more flexible fixtureless approaches. Due to the time-consuming and costly nature of recording and producing erroneous weld seams, such recordings and datasets are rarely available in this area. This often limits the research towards adaptable fixtureless welding setups. Because of this, we present a multi-modal dataset consisting of 100 recorded welds that tracks the metal sheets movement. The developed setup enables the determination of boundary conditions for fixtureless welding. Two types of sensors record the welding process. First, three inductive probes are applied to record the metal sheets` movement and second, a long-wave infrared (LWIR) camera records changes in the thermal radiation field. Two different welding speeds and laser powers were used to produce a variety of welds. The dataset can be used for data-driven algorithms to predict the metal movement, analyze the thermal radiation field, or develop quality control methodologies.}, language = {en} } @misc{DiegelSchrickerSchmidtetal., author = {Diegel, Christian and Schricker, Klaus and Schmidt, Leander and Seibold, Marc and Friedmann, Hannes and Hellwig, Peter and Fr{\"o}hlich, Fabian and Nagel, Falk and Kallage, Peter and Rack, Alexander and Requardt, Herwig and Chen, Yunhui and Bergmann, Jean Pierre}, title = {In situ characterization of keyhole behavior and spatter formation in full penetration laser beam welding with local gas flow using high-speed synchrotron X-ray imaging}, series = {Optics \& laser technology}, volume = {191}, journal = {Optics \& laser technology}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0030-3992}, doi = {10.1016/j.optlastec.2025.113367}, pages = {1 -- 17}, abstract = {Spatter formation is a major issue at welding speeds above 8 m/min for full penetration laser beam welding of high-alloyed steels. In experiments using a local gas flow directed at the keyhole rear wall, a reduction in spatter formation on the specimen top side was observed for welding of AISI 304. However, the interaction between gas flow and keyhole behavior with respect to the mechanisms and locations of spatter detachment, especially on the bottom side, is not yet fully understood. High-speed synchrotron X-ray imaging enables detailed insights into the keyhole behavior and the spatter formation to obtain a deeper understanding of the underlying mechanisms. During the reference experiments welding without shielding gas flow, the spatter detach from a melt pool swelling behind the keyhole aperture on both sides of the sheet. A gas flow with a low flow rate of 4.8 L/min reduces the spatter formation on the top side and the keyhole length due to the absence of oxygen affecting the surface tension. A swelling also forms on the keyhole front on the bottom side and small spatter detach undirected. Increasing the flow rate to 12.8 L/min elongates the keyhole, particularly on the specimen top side. The increased momentum transfer of the gas flow results in a periodic keyhole oscillation on the specimen top side. In combination with an elongated melt pool, the oscillation is directly correlated with the hump formation, caused by melt being pushed over the already solidified weld seam. In addition, spatter does not detach from the top side due to the changed melt flow and only detach from the keyhole front on the bottom side.}, language = {en} } @misc{ErmilovaHlushkovaVolchuk, author = {Ermilova, E. and Hlushkova, D.B. and Volchuk, V.M.}, title = {The effect of plasma coatings on the properties of low-alloy steels}, series = {Functional materials}, volume = {32}, journal = {Functional materials}, number = {1}, publisher = {National Academy of Sciences of Ukraine (Co. LTD Ukrinformnauka) (Publications)}, address = {Charkiw}, issn = {1027-5495}, doi = {10.15407/fm32.01.50}, pages = {50 -- 55}, abstract = {The paper considers the possibility of using ion-plasma spraying of coatings on low-alloy steels 4Х5MFS and 5ХNM. The choice of these grades is due to the fact that they do not contain tungsten, given the sharp increase in its deficiency, and the molybdenum content is limited, and these steels also meet the requirements for the substrate material on which the titanium nitride coating is applied. The coatings were applied by the method of condensation of the substance under ion bombardment conditions. To determine the required nitrogen pressure, titanium nitride is applied at different partial nitrogen pressures - from 310 -3 to 1 Pa. Coatings obtained under different nitrogen pressures differ in the amount and size of the droplet phase. The largest amount of the droplet phase containing α-Ti is observed in coatings obtained at nitrogen pressures of 3x10-3 Pa, 3x10-2 Pa. An increase in nitrogen pressure (4·10-1 Pa, 1 Pa) significantly reduces the level of microdistortions of crystal lattices in the coating, its plasticity increases. In this regard, the fragility of the coating decreases with its sufficiently high hardness. As laboratory tests have shown, a titanium nitride coating applied under optimal technological parameters increases the corrosion resistance of the materials on which it is applied three times, and scale resistance - two to four times.}, language = {en} } @misc{NikitinHlushkovaVolchuketal., author = {Nikitin, A. and Hlushkova, D.B. and Volchuk, V.M. and Ragulin, V.M.}, title = {Multifractal approach to assessing the heterogeneity of carbon alloys}, series = {Functional materials}, volume = {32}, journal = {Functional materials}, number = {1}, publisher = {National Academy of Sciences of Ukraine (Co. LTD Ukrinformnauka) (Publications)}, address = {Charkiw}, issn = {1027-5495}, doi = {10.15407/fm32.01.161}, pages = {161 -- 165}, abstract = {A multifractal structural analysis of carbon alloy structures after multi-stage flow processing was carried out. The statistical dimensions of the D-300 structure varied from 4.18 to 2.47, indicating the compactness of filling the space with martensite, bainite and pearlite. Indicators of the statistical dimension of cementite in the range from 2.18 to 1.55 characterize the dimension of the D300 structure. The fractal D0, information D1, correlation D2 dimensions of martensite, bainite, pearlite also varied in the range from 2.66 to 2.13, indicating the heterogeneity of the structure. A one-to-one correspondence between the multifractal indicators of the structure and the hardness of the iron-carbon alloy was established.}, language = {en} } @misc{MorozovaObrosovNaumovetal., author = {Morozova, Iuliia and Obrosov, Aleksei and Naumov, Anton and Michailov, Vesselin and Doynov, Nikolay}, title = {Factors affecting mechanical properties of impulse friction stir welded AA2024-T351 under static and cyclic loads}, series = {Machines}, volume = {13}, journal = {Machines}, number = {6}, editor = {Markopoulos, Angelos P. and Astolfi, Davide}, publisher = {MDPI}, address = {Basel}, issn = {2075-1702}, doi = {10.3390/machines13060529}, pages = {1 -- 16}, abstract = {This study investigates the factors affecting the mechanical performance of conventional and impulse friction stir welded (FSW and IFSW) AA2024-T351 joints under static and cyclic loading. Emphasis is placed on the influence of fracture-inducing features such as oxide inclusions, constituent particle distributions, crystallographic texture, and precipitation state. A series of IFSW welds produced at varying impulse parameters were compared to conventional FSW welds in terms of microhardness, tensile strength, fatigue life, and Taylor factor distribution. IFSW joints demonstrated a significant improvement in tensile strength and elongation, particularly at higher impulse frequencies. Enhanced material mixing due to the reciprocating tool motion in IFSW resulted in finer particle distribution, more favorable crystallographic texture, and reduced weld pitch, all contributing to increased ductility and strength. Fractographic analyses revealed that fatigue failures primarily initiated in the stir zone, typically at unplasticized metallic inclusions. However, IFSW joints displayed longer fatigue lives, particularly when impulse parameters were optimized. These findings underline the complex interplay of microstructural and textural factors in determining weld performance, highlighting IFSW as a promising technique for enhancing the durability of high-strength aluminum welds.}, language = {en} } @misc{SchrickerSchmidtNageletal., author = {Schricker, Klaus and Schmidt, Leander and Nagel, Falk and Diegel, Christian and Friedmann, Hannes and Seibold, Marc and Hellwig, Peter and Fr{\"o}hlich, Fabian and Kallage, Peter and Chen, Yunhui and Requardt, Herwig and Rack, Alexander and Bergmann, Jean Pierre}, title = {A comprehensive study on the influence of spatial power distribution on time-dependent keyhole behavior in laser beam welding of copper by means of high-speed synchrotron X-ray imaging}, series = {Optics \& laser technology}, volume = {192, Part E}, journal = {Optics \& laser technology}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0030-3992}, doi = {10.1016/j.optlastec.2025.113999}, pages = {1 -- 15}, abstract = {This paper examines the impact of spatial power distributions on the time-dependent keyhole behavior during laser beam welding of copper using high-speed synchrotron X-ray imaging. The experimental setup utilized a COHERENT HighLight FL8000-ARM fiber laser with concentric intensity distribution created by an optical fiber cable. The European Synchrotron Radiation Facility (ESRF, beamline ID19) was used to conduct high-speed synchrotron imaging at 20,000 images per second to study the spatio-temporal keyhole behavior. Keyhole geometries were extracted through advanced image processing techniques, allowing quantification of parameters like depth, aperture, bulging, and determination of related oscillation frequencies. The results showed that core-dominated processes exhibit significant variations in keyhole geometry. In contrast, ring-dominated processes exhibited reduced penetration depths but increased melt pool dynamics due to altered absorption conditions and increased temperatures within the melt pool. A stabilized core-ring power distribution minimized fluctuations, resulting in improved process stability. The findings were summarized in a model concept describing three characteristic keyhole regimes: core-dominated, ring-dominated, and stabilized core-ring processes.}, language = {en} } @misc{KotlarskiOrmanovaNikitinetal., author = {Kotlarski, Georgi and Ormanova, Maria and Nikitin, Alexander and Parasar, Ashirwad and Ossenbrink, Ralf and Doynov, Nikolay and Valkov, Stefan and Michailov, Vesselin}, title = {Wire arc deposition of specimens using a special-designed aluminum-cored wire with CNTs}, series = {Journal of physics : conference series}, volume = {2994}, journal = {Journal of physics : conference series}, number = {1}, publisher = {IOP Publishing}, address = {Bristol}, issn = {1742-6588}, doi = {10.1088/1742-6596/2994/1/012024}, pages = {1 -- 6}, abstract = {This work investigated the possibility of manufacturing components using an aluminum welding wire with an aluminum powder core reinforced with carbon nanotubes (CNTs). Appropriate technological conditions of deposition were selected for the successful manufacturing of a wall-shaped specimen. The last was built using a multi-track approach. The results indicated the presence of a large quantity of pores within the volume of the specimen with values of over 30\%. Regardless of the high defect quantity within the specimen a number of successfully integrated carbon nanoparticles were detected in certain areas of the cross-section of the specimen in the form of an Al₄C₃ composite.}, language = {en} } @misc{ZaissPowellHaasetal., author = {Zaiß, Felix and Powell, John and Haas, Michael and Wahl, Johannes and Diegel, Christian and Schricker, Klaus and Bergmann, Jean Pierre and Hummel, Marc and Spurk, Christoph and Olowinsky, Alexander and Beckmann, Felix and Moosmann, Julian and Hagenlocher, Christian and Graf, Thomas}, title = {The influence of different core-ring intensity distributions on the capillary shape and resulting weld in laser welding of steel}, series = {Optics \& laser technology}, volume = {194}, journal = {Optics \& laser technology}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0030-3992}, doi = {10.1016/j.optlastec.2025.114495}, pages = {1 -- 12}, abstract = {Laser welding was carried out using a co-axial core-ring beam, with independent control of the power to the core and the ring. The welding process was observed using high-power X-rays and high-speed imaging equipment. Adjusting the relative powers of the core and the ring beams was found to have profound effects on the shape of both the capillary created and the weld melt pool. Moderate laser power densities in the ring were found to increase the top diameter of the weld pool and reduce fluctuations in the welding process. High laser power densities in the ring led to the creation of a second capillary which largely acted independently of the capillary generated by the laser power in the core. At high power densities and welding speeds the two capillaries were almost completely separated in the direction of travel.}, language = {en} } @misc{ZaissPowellHaasetal., author = {Zaiß, Felix and Powell, John and Haas, Michael and Diegel, Christian and Schricker, Klaus and Bergmann, Jean Pierre and Spurk, Christoph and Hummel, Marc and Olowinsky, Alexander and Beckmann, Felix and Moosmann, Julian and Hagenlocher, Christian and Graf, Thomas}, title = {Core-ring laser welding : the influence of ring diameter on the capillary dynamics and the formation of pores in the resulting weld}, series = {Lasers in manufacturing and materials processing}, journal = {Lasers in manufacturing and materials processing}, publisher = {Springer Science and Business Media LLC}, address = {New York, NY}, issn = {2196-7229}, doi = {10.1007/s40516-026-00331-1}, pages = {21}, abstract = {Double-core fibers that deliver laser beams with adjustable amounts of power to the central core and the surrounding ring component of the fiber are of major interest for optimizing laser welding processes. However, the central focussed laser spot and the ring diameters are fixed by the fiber dimensions, the focusing optics, and the laser systems involved. This work investigates the influence of different ring beam diameters, with a constant central spot diameter, on the capillary dynamics and the formation of pores in the resulting welds in 1.4301 stainless steel (X5CrNi18-10, AISI 304). The different core-ring configurations were achieved using specially designed beam-shaping optics. The generation of pores during the welding process was examined by means of synchrotron X-ray imaging. The results show that different ring diameters have a profound effect on the melt pool geometry, the capillary shape and the location of the capillary collapse which gives rise to pore formation in the weld. In the examples presented here, larger ring diameters extended the melt pool in the direction of welding without contributing directly to the capillary evaporation. In this case the narrow, deep capillaries which are created by the core beam alone can bulge and collapse, trapping vapor and gas to create large pores. If, however, the ring beam has a small enough diameter, it can help to produce a wider capillary which does not trap gas and create pores in the same way. The mechanisms by which large bubbles in the melt can result in non-spherical pores in the weld are also explained.}, language = {en} }