TY - CONF A1 - Yang, Chunliang A1 - Wu, Chuansong A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Numerical analysis of ultrasonic vibration enhanced friction stir welding of dissimilar Al/Mg alloys N2 - The ultrasonic vibration enhanced friction stir welding (UVeFSW) process has unique advantages in joining dissimilar Al/Mg alloys. While there are complex coupling mechanisms of multi-fields in the process, it is of great significance to model this process, to reveal the influence mechanism of ultrasonic vibration on the formation of Al/Mg joints. In this study, the acoustic-plastic constitutive equation was established by considering the influence of both ultrasonic softening and residual hardening on the flow stress at different temperatures and strain rates. And the ultrasonic induced friction reduction (UiFR) effect on friction coefficient in different relative directions at the FSW tool-workpiece interface was quantitatively calculated and analyzed. The Al/Mg UVeFSW process model was developed through introducing the above acoustic effects into the model of Al/Mg friction stir welding (FSW). The ultrasonic energy is stronger on the aluminum alloy side. In the stirred zone, there is the pattern distribution of ultrasonic sound pressure and energy. The heat generation at the tool-workpiece contact interface and viscous dissipation were reduced after applying ultrasonic vibra-tion. Due to the UiFR effect, the projection of friction coefficient and heat flux distributions at the tool-workpiece interface present a "deformed" butterfly shape. The calculated results show that ultrasonic vibra-tion enhanced the material flow and promoted the mixing of dissimilar materials. T2 - 13th International Seminar Numerical Analysis of Weldability CY - Seggau, Austria DA - 04.09.2022 KW - Friction stir welding KW - Ultrasonic vibration KW - Al/Mg alloys KW - Numerical simulation PY - 2023 SN - 2410-0544 VL - 13 SP - 517 EP - 538 PB - Verlag der Technischen Universität Graz AN - OPUS4-58805 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Artinov, Antoni A1 - Meng, Xiangmeng A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Numerical analysis of the partial penetration high power laser beam welding of thick sheets at high process speeds N2 - The present work is devoted to the numerical analysis of the high-power laser beam welding of thick sheets at different welding speeds. A three-dimensional transient multi-physics numerical model is developed, allowing for the prediction of the keyhole geometry and the final penetration depth. Two ray tracing algorithms are implemented and compared, namely a standard ray tracing approach and an approach using a virtual mesh refinement for a more accurate calculation of the reflection points. Both algorithms are found to provide sufficient accuracy for the prediction of the keyhole depth during laser beam welding with process speeds of up to 1.5 m/min. However, with the standard algorithm, the penetration depth is underestimated by the model for a process speed of 2.5 m/min due to a trapping effect of the laser energy in the top region. In contrast, the virtually refined ray tracing approach results in high accuracy results for process speeds of both 1.5 m/min and 2.5 m/min. A detailed study on the trapping effect is provided, accompanied by a benchmark including a predefined keyhole geometry with typical characteristics for the high-power laser beam welding of thick plates at high process speed, such as deep keyhole, inclined front keyhole wall, and a hump. KW - High-power laser beam welding KW - High process speeds KW - Deep penetration KW - Numerical modeling KW - Ray tracing PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-532170 DO - https://doi.org/10.3390/met11081319 SN - 2075-4701 VL - 11 IS - 8 SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-53217 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yang, Fan A1 - Meng, Xiangmeng A1 - Bachmann, Marcel A1 - Artinov, Antoni A1 - Putra, Stephen Nugraha A1 - Rethmeier, Michael T1 - Numerical analysis of the influence of an auxiliary oscillating magnetic field on suppressing the porosity formation in deep penetration laser beam alloys of aluminum alloys N2 - The contactless magnetohydrodynamic technology has been considered as a potential and promising method to improve the weld qualities of deep penetration laser beam welding. In this paper, numerical investigations are conducted to study the influence of the auxiliary oscillating magnetic field on the porosity suppression in laser beam welding of 5754 aluminum alloy. To obtain a deeper insight into the suppression mechanism, a three-dimensional transient multi-physical model is developed to calculate the heat transfer, fluid flow, keyhole dynamic, and magnetohydrodynamics. A ray tracing algorithm is employed to calculate the laser energy distribution on the keyhole wall. A time-averaged downward Lorentz force is produced by an oscillating magnetic field. This force acts in the molten pool, leading to a dominant downward flow motion in the longitudinal section, which blocks the bubble migration from the keyhole tip to the rear part of the molten pool. Therefore, the possibility for the bubbles to be captured by the solidification front is reduced. The electromagnetic expulsive force provides an additional upward escaping speed for the bubbles of 1 m/s ~ 5 m/s in the lower and middle region of the molten pool. The simulation results are in a good agreement with experimental measurements. Based on the results obtained in this study, a better understanding of the underlying physics in laser beam welding enhanced by an auxiliary oscillating magnetic field can be provided and thus the welding process can be further optimized reducing the porosity formation. T2 - 13th International Seminar Numerical Analysis of Weldability CY - Seggau, Austria DA - 04.09.2022 KW - Deep penetration laser beam welding KW - Oscillating magnetic field KW - Numerical simulation KW - Porosity KW - Molten pool behaviour PY - 2023 SN - 2410-0544 VL - 13 SP - 237 EP - 254 PB - Verlag der Technischen Universität Graz AN - OPUS4-58804 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yang, Fan A1 - Meng, Xiangmeng A1 - Putra, Stephen Nugraha A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Numerical analysis of the effect of the metal vapor plume on the keyhole and the molten pool behavior during deep penetration laser beam welding N2 - The effect of the oscillating metal vapor plume on the keyhole and molten pool behavior during the laser beam welding of AlMg3 aluminum alloys is investigated by the experimental and numerical method. The real-time height of the metal vapor plume is measured by high-speed camera observation. The obtained experimental results are used to evaluate the additional heating source and laser beam attenuation caused by the scattering and absorption based on the Beer-Lambert theory. Furthermore, the dynamic behavior of the metal vapor plume is incorporated into a 3D transient heat transfer and fluid flow model, coupled with the ray tracing method, for the laser beam welding of the AlMg3 alloy. It is found that the additional heating resulting from the scattered and absorbed laser beam energy by the metal vapor plume significantly expands the shape of the molten pool on the top region. Moreover, the oscillating metal vapor plume caused the fluctuation of the molten pool shape. The probability of keyhole collapse at the bottom increases significantly to 72% due to the oscillating laser power induced by the laser beam attenuation. The internal interplay between the metal vapor plume, molten pool shape, and the keyhole collapse are obtained. The developed model has been validated by the experiments, which shows a good agreement. T2 - International Congress of Applications of Lasers & Electro-Optics 2023 CY - Chicago, Illinois, USA DA - 16.10.2023 KW - Deep penetration laser beam welding KW - Numerical simulation KW - Oscillating vapor plume KW - Keyhole collapse PY - 2023 SP - 1 EP - 10 AN - OPUS4-58841 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yang, Fan A1 - Meng, Xiangmeng A1 - Putra, Stephen Nugraha A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Numerical analysis of the effect of an oscillating metal vapor plume on the keyhole and molten pool behavior during deep penetration laser beam welding N2 - The effect of the oscillating metal vapor plume on the keyhole and molten pool behavior during the laser beam welding of AlMg3 aluminum alloys is investigated by experimental and numerical methods. The real-time height of the metal vapor plume is measured by high-speed camera observation. The obtained experimental results are used to evaluate the additional heating source and laser beam attenuation caused by the scattering and absorption based on the Beer–Lambert theory. Furthermore, the dynamic behavior of the metal vapor plume is incorporated into a 3D transient heat transfer and fluid flow model, coupled with the ray tracing method, for the laser beam welding of the AlMg3 alloy. It is found that additional heating resulting from the scattered and absorbed laser beam energy by the metal vapor plume significantly expands the shape of the molten pool on the top region. Moreover, the oscillating metal vapor plume caused the fluctuation of the high-temperature region in the molten pool. The probability of keyhole collapse at the bottom increases 17% due to the oscillating laser power induced by the laser beam attenuation. The internal interplay between the metal vapor plume, molten pool shape, and keyhole collapse is obtained. The developed model has been validated by experiments, which shows a good agreement. T2 - International Congress of Applications of Lasers & Electro-Optics 2023 CY - Chicago, IL, USA DA - 16.10.2023 KW - Deep penetration laser beam welding KW - Numerical simulation KW - Oscillating vapor plume KW - Keyhole collapse PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-587978 DO - https://doi.org/10.2351/7.0001094 SN - 1938-1387 SN - 1042-346X VL - 35 IS - 4 SP - 1 EP - 10 PB - AIP Publishing CY - Melville, NY AN - OPUS4-58797 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Artinov, Antoni A1 - Kising, Pascal A1 - Bachmann, Marcel A1 - Meng, Xiangmeng A1 - Rethmeier, Michael T1 - Numerical analysis of the dependency of the weld pool shape on turbulence and thermodynamic activity of solutes in laser beam welding of unalloyed steels N2 - A three-dimensional numerical model was developed to accurately predict the steady-state weld pool shape in full penetration laser beam welding. The model accounts for the coupling between the heat transfer and the fluid dynamics by considering the effects of solid/liquid phase transition, thermo-capillary convection, natural convection, and phase-specific and temperature-dependent material properties up to the evaporation temperature. A fixed right circular cone was utilized as a keyhole geometry to consider the heat absorbed from the laser beam. The model was used to analyze the influence of the thermodynamic activity of solutes and turbulence on the weld pool shape. A mesh sensitivity analysis was performed on a hybrid mesh combining hexahedral and tetrahedral elements. For the case of full penetration laser beam welding of 8 mm thick unalloyed steel sheets, the dependence of the weld pool shape on the surface-active element sulfur was found to be negligible. The analysis of the results showed that a laminar formulation is sufficient for accurately predicting the weld pool shape since the turbulence has a minor impact on the flow dynamics in the weld pool. The validity of the numerical results was backed up by experimental measurements and observations, including weld pool length, local temperature history, and a range of metallographic crosssections. T2 - 13th International Seminar Numerical Analysis of Weldability CY - Seggau, Austria DA - 04.09.2022 KW - Weld pool shape KW - Numerical modeling KW - Laser beam welding KW - Thermo-capillary convection KW - Turbulence PY - 2023 SN - 978-3-85125-968-1 SN - 978-3-85125-969-8 SN - 2410-0544 VL - 13 SP - 161 EP - 188 PB - Verlag der Technischen Universität Graz AN - OPUS4-58803 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gebhardt, M.O. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Numerical analysis of hot cracking in laser-hybrid welded tubes N2 - In welding experiments conducted on heavy wall pipes, the penetration mode (full or partial penetration) occurred to be a significant factor influencing appearance of solidification cracks. To explain the observed phenomena and support further optimization of manufacturing processes, a computational model was developed, which used a sophisticated strategy to model the material. High stresses emerged in the models in regions which showed cracking during experiments. In partial penetration welding, they were caused by the prevention of weld shrinkage due to the cold and strong material below the joint. Another identified factor having an influence on high stress localization is bulging of the weld. PY - 2013 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-302961 DO - https://doi.org/10.1155/2013/520786 SN - 1687-8442 SN - 1687-8434 IS - Article ID 520786 SP - 1 EP - 8 PB - Hindawi Publishing Corporation CY - New York, NY, USA AN - OPUS4-30296 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bakir, Nasim A1 - Pavlov, V. A1 - Zavjalov, S. A1 - Volvenko, S. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Novel metrology to determine the critical strain conditions required for solidification cracking during laser welding of thin sheets N2 - This paper represents the results for proposed optical flow method based on the Lucas-Kanade (LK) algorithm applied to two different problems. The following observations can be made: - The estimated strain and displacement for conducted tensile test are generally very close to those measured with conventional DIC-technique. - The LK technique allows measurement of strain or displacement without special selection of a region of interest. Using a novel optical measurement technique together with the optical flow algorithm, a twodimensional deformation analysis during welding was conducted. This technique is the first to provide a measurement of the full strain field locally in the immediate vicinity of the solidification front. Additionally, the described procedure of the optical measurement allows the real material-dependent values of critical strain characterizing the transition to hot cracking during laser welding processes to be determined. T2 - Beam Technologies and Laser Application CY - Sankt Petersburg, Russia KW - Hot cracking test KW - Local critical strain KW - Solidification cracking KW - Laser beam welding KW - Novel metrology PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-467226 DO - https://doi.org/10.1088/1742-6596/1109/1/012047 SN - 1742-6596 VL - 1109 IS - 012047 SP - 1 EP - 9 PB - IOP Publ. CY - Bristol AN - OPUS4-46722 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gook, S. A1 - Krieger, S. A1 - Gumenyuk, Andrey A1 - El-Batahgy, A. M. A1 - Rethmeier, Michael T1 - Notch impact toughness of laser beam welded thick sheets of cryogenic nickel alloyed steel X8Ni9 N2 - The paper deals with the investigations of the impact toughness of laser beam welded 14.5 mm thick sheets made of cryogenic steel X8Ni9 as a function of preheating. This 9% nickel alloyed steel is widely used in the liquefied natural gas (LNG) industry. An application of highly efficient welding processes such as high-power laser beam welding (LBW) in LNG sector requires an understanding of the interactions between the LBW process parameters and weld properties, in particular the impact toughness. The results show that the original fine-grained martensitic microstructure of the base metal (BM) is significantly changed by melting and crystallization during the LBW, what can lead to a decrease in the impact toughness of the weld metal (WM) below the required level. An optimal preheating temperature range leads to the favorable thermal welding cycle and is of remarkable importance for maintaining the notch impact toughness of laser beam welded joints of these thick steel sheets. A parameter window was identified in which V-notch impact toughness comparable to that of the BM at -196 °C was achieved. KW - Cryogenic steel KW - Laser beam welding KW - Preheating KW - Welding thermal cycle KW - Microstructure KW - Hardness KW - V-notch impact toughness PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-513250 DO - https://doi.org/10.1016/j.procir.2020.09.095 VL - 94 SP - 627 EP - 631 PB - Elsevier B.V. AN - OPUS4-51325 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael A1 - Gook, Sergej A1 - Krieger, Steffen A1 - Gumenyuk, Andrey A1 - El-Batahgy, Abdel-Monem T1 - Notch impact toughness of laser beam welded thick sheets of cryogenic nickel alloyed steel X8Ni9 N2 - This research work deals with the investigations of the impact toughness of laser beam welded 14.5 mm thick sheets made of cryogenic steel X8Ni9 as a function of preheating. This 9% nickel alloyed steel is widely used in the liquefied natural gas (LNG) industry. An application of highly efficient welding processes such as high-power laser beam welding (LBW) in LNG sector requires an understanding of the interactions between the LBW process parameters and weld properties, in particular the impact toughness. The results show that the original fine-grained martensitic microstructure of the base metal (BM) is significantly changed by melting and crystallization during the LBW, what can lead to a decrease in the impact toughness of the weld metal (WM) below the required level. An optimal preheating temperature range leads to the favorable thermal welding cycle and is of remarkable importance for maintaining the notch impact toughness of laser beam welded joints of these thick steel sheets. A parameter window was identified in which V-notch impact toughness comparable to that of the BM at -196 °C was achieved. T2 - 11th CIRP Conference on Photonic Technologies LANE 2020 CY - Online meeting DA - 06.09.2020 KW - Cryogenic steel KW - Laser beam welding KW - Welding thermal cycle PY - 2020 AN - OPUS4-51750 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Üstündag, Ömer A1 - Bakir, Nasim A1 - Gook, S. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Neueste Entwicklungen im Bereich des Hochleistungslaserstrahl- und Hybridschweißens von hohen Blechdicken N2 - Bislang kommt das Laserstrahlschweißen bzw. Laserhybridschweißen hauptsächlich bei Dickblechen mit einer Wandstärke von bis zu 15 mm zum Einsatz. Für Anwendungen über 20 mm war dieses Verfahren aufgrund einiger Herausforderungen bisher nur bedingt realisierbar. Eine von der Bundesanstalt für Materialforschung und -prüfung (BAM) entwickelte elektromagnetische Schmelzbadunterstützung ermöglicht nun ein einlagiges Schweißen von bis zu 30 mm Wandstärke. KW - Laserstrahlschweißen KW - Laserhybridschweißen KW - Modellierung KW - Elektromagnetische Schmelzbadunterstützung KW - Kaltzähe Stähle PY - 2020 VL - 2 SP - 26 EP - 30 PB - DVV Media Group GmbH CY - Hamburg AN - OPUS4-51632 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Nahteigenschaftsverbesserung von dickwandigen laserstrahlgeschweißten Duplexblechen mittels pulveraufgetragenen Pufferschichten N2 - Duplexstähle finden aufgrund ihrer Eigenschaften, wie der guten Korrosionsbeständigkeit, einer hohen Festigkeit bei gleichzeitig guter Duktilität häufig industrielle Anwendung. Durch die hohen Abkühlraten beim Laserstrahlschweißen weisen Schweißnähte jedoch anstelle eines ausgeglichenen Duplexgefüges einen deutlich erhöhten Ferritanteil, im Vergleich zum Basiswerkstoff, auf. Dies führt zu einer verringerten Duktilität sowie Korrosionsbeständigkeit. Um dieses Problem zu lösen, wurde ein Prozess entwickelt, der auf einer Kantenbeschichtung mit nickelhaltigem Zusatzmaterial der zu fügenden Bleche mittels Laser-Pulver-Auftragschweißen (LPA) basiert. Die resultierenden Schweißnähte wurden zerstörend anhand von Schliffbildern, EDX-Aufnahmen, Härtemessungen und Kerbschlagbiegeversuchen geprüft. T2 - 40. Assistentenseminar der Füge- und Schweißtechnik CY - Braunlage, Germany DA - 25.09.2019 KW - Laser-Pulver-Auftragschweißen; Laserstrahlschweißen, Duplex, Pufferschichten PY - 2020 VL - 357 SP - 131 EP - 140 PB - DVS Media CY - Düsseldorf AN - OPUS4-50144 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gook, S. A1 - El-Sari, B. A1 - Biegler, M. A1 - Rethmeier, Michael A1 - Lichtenthäler, F. A1 - Stark, M. T1 - Multiple-wire submerged arc welding of high-strength fine-grained steels N2 - Ensuring the required mechanical-technological properties of welds is a critical issue in the application of multi-wire submerged arc welding processes for welding high-strength fine-grained steels. Excessive heat input is one of the main causes for microstructural zones with deteriorated mechanical properties of the welded joint, such as a reduced notched impact strength and a lower structural robustness. A process variant is proposed which reduces the weld volume as well as the heat input by adjusting the welding wire configuration as well as the energetic parameters of the arcs, while retaining the advantages of multiwire submerged arc welding such as high process stability and production speed. KW - Submerged arc welding KW - High-strength fine-grained steels KW - Mechanical properties of the joints KW - Energy parameters of the arc PY - 2022 DO - https://doi.org/10.37434/tpwj2022.01.02 SN - 0957-798X IS - 1 SP - 9 EP - 13 PB - Paton Publishing House CY - Kiev AN - OPUS4-54701 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Rethmeier, Michael A1 - Karkhin, V. A1 - Khomich, P. T1 - Modeling of hydrodynamic and thermal processes at laser welding with through penetration N2 - A mathematical model for physical processes in fusion welding has been developed. It is based on the equivalent heat source concept and consists of two parts: thermo-hydrodynamics of the weld pool and heat conduction in the weldment outside the pool. In thermo-hydrodynamic problem, temperature – dependent material properties, keyhole shape, thermo-capillary and natural convection, phase transformations and other physical phenomena are taken into consideration. Solution of the thermo-hydrodynamic problem by the finite element method is demonstrated with keyhole laser beam welding of a 15 mm thick steel plate. Thermo-capillary convection is primarily responsible for the intricate convex-concave melt pool shape and pool enlargement near the plate surfaces. The calculated and experimental molten pool dimensions are in close agreement. KW - Laser welding KW - Weld pool modeling KW - Heat conduction KW - Greens function method PY - 2021 DO - https://doi.org/10.1080/09507116.2021.1989209 SP - 1 EP - 12 PB - Taylor & Francis Group AN - OPUS4-54022 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Simón Muzás, Juan A1 - Brunner-Schwer, C. A1 - Rethmeier, Michael A1 - Hilgenberg, Kai T1 - Mitigation of liquation cracking in laser welding of pairs of L-PBF processed and wrought plates of Inconel 718 N2 - Laser welding is an appropriate technique for joining Laser Powder Bed Fusion (L-PBF) parts together and to conventional wrought ones. The potential consists of profiting from synergies between additive and conventional manufacturing methods and overcoming the existing limitations of both. On the one hand, L-PBF is a widely spread metal-based additive manufacturing technique suitable for generating complex parts which can present intrinsic designed cavities, conformal cooling channels, and filigree structures contributing to sustainable manufacturing and efficiency-oriented designs. On the other hand, chamber sizes for producing L-PBF parts are limited, and the process is time-consuming. Thus, its employment is not for every geometry justified. Additionally, they are in most cases individual elements of a larger assembly and need to be joined together to conventionally fabricated parts. The present research suggests laser welding parameters to adequately bond pairs of wrought and L-PBF processed plates and two L-PBF plates of Inconel 718 in butt position. L-PBF samples are printed in three different build-up orientations. Additionally, the influence of as-built L-PBF roughness qualities and usual pre-weld preparations such as edge milling are examined. The effect of normed pre-weld heat treatments is also contemplated. Identified cracks are analyzed by means of EDS in order to confirm the present phases on the areas of interest. EBSD is also employed to obtain a clear depiction of the crystallographic texture and distribution of the hot cracks. The quality of the weldment was examined according to existing standards. Substantial differences in seam geometry and microstructure across different edge’s surface qualities and build directions of stress relieved L-PBF parts have not been detected. Nevertheless, even if no other irregularities are present in the seam, variability in liquation cracking susceptibility has been confirmed. This defect is prone to happen when parts made of this nickel-based superalloy are welded together when not enough precautions are taken. It has been determined that grain size and ductility of the material before welding play a crucial role and mitigating or intensifying these imperfections. Moreover, recommendations are presented to avoid this potential welding defect. T2 - IIW 2022 International Conference on Welding and Joining CY - Tokyo, Japan DA - 17.07.2022 KW - Hybrid Part KW - Liquation Cracking KW - Build-up Orientation KW - Pre-weld Preparation KW - Heat treatment KW - Inconel 718 KW - Laser Welding KW - Laser Powder Bed Fusion KW - Selective Laser Melting KW - SLM KW - L-PBF KW - PBF-LB/M KW - LW PY - 2022 UR - www.iiw2022.com SP - 372 EP - 375 PB - The International Institute of Welding (IIW) CY - Tokyo, Japan AN - OPUS4-56066 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Petrat, T. A1 - Brunner-Schwer, C. A1 - Graf, B. A1 - Rethmeier, Michael T1 - Microstructure of Inconel 718 parts with constant mass energy input manufactured with direct energy deposition N2 - The laser-based direct energy deposition (DED) as a technology for additive manufacturing allows the production of near net shape components. Industrial applications require a stable process to ensure reproducible quality. Instabilities in the manufacturing process can lead to faulty components which do not meet the required properties. The DED process is adjusted by various parameters such as laser power, velocity, powder mass flow and spot diameter, which interact with each other. A frequently used comparative parameter in welding is the energy per unit length and is calculated from the laser power and the velocity in laser welding. The powder per unit length comparative parameter in the DED process has also be taken into account, because this filler material absorbs energy in addition to the base material. This paper deals with the influence of mass energy as a comparative parameter for determining the properties of additively manufactured parts. The same energy per unit length of 60 J/mm as well as the same powder per unit length of 7.2 mg/mm can be adjusted with different parameter sets. The energy per unit length and the powder per unit length determine the mass energy. The laser power is varied within the experiments between 400 W and 900 W. Energy per unit length and powder per unit length are kept constant by adjusting velocity and powder mass flow. Using the example of Inconel 718, experiments are carried out with the determined parameter sets. In a first step, individual tracks are produced and analyzed by means of micro section. The geometry of the tracks shows differences in height and width. In addition, the increasing laser power leads to a higher dilution of the base material. To determine the suitability of the parameters for additive manufacturing use, the individual tracks are used to build up parts with a square base area of 20x20 mm². An investigation by Archimedean principle shows a higher porosity with lower laser power. By further analysis of the micro sections, it can be seen that at low laser power, connection errors occur between the tracks. The results show that laser power, velocity and powder mass flow have to be considered in particular, because a constant mass energy can lead to different geometric as well as microscopic properties. KW - Direct energy deposition KW - Porosity KW - Inconel 718 KW - Additive manufacturing KW - Laser metal deposition PY - 2019 SN - 2351-9789 SP - 1 EP - 12 PB - Elsevier B.V. AN - OPUS4-50007 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fu, B. A1 - Shen, J. A1 - Suhuddin, U. A1 - Su, H. A1 - dos Santos, J. A1 - Rethmeier, Michael T1 - Microstructure and mechanical properties of a modified refill friction stir spot welds of AM50 magnesium alloy N2 - Magnesium (Mg) alloys have attracted much attention due to their merits of meeting requirements of lightweight, energy-efficient and environmental friendly engineering. In this study, a modified refill friction stir spot welding (refill-FSSW) method is proposed to weid AMSO Mg alloy, in which pin and sleeve rotate at different states. Effects of process parameters on the microstructure, material flow, and mechanical properties of welds were studied. Results showed that, the modified refill-FSSW technology could enhance the intennixing of material by changing the flow state. Lap shear strength of welds could be significantly improved with changed failure modes. The modified refill FSSW technology is a competitive welding method for Mg alloy. T2 - 7th International Conference on Welding Science and Engineering in conjunction with 3rd International Symposium on Computer-Aided Welding Engineering CY - Jinan, China DA - 18.10.2017 KW - Refill friction stir spot welding KW - Friction spot welding KW - Magnesium KW - Microstructure KW - Mechanical properties PY - 2017 SP - 203 EP - 206 AN - OPUS4-43234 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gook, Sergej A1 - Üstündag, Ömer A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Method for defect-free hybrid laser-arc welding of closed circumferential welds N2 - This paper presents investigation results of a process for defect-free hybrid laser arc welding (HLAW) of closed circumferential welds. The process aims to avoid weld imperfections in the overlap area of a HLAW circumferential weld. A process control strategy for closing the circumferential weld was developed to achieve a defect-free overlap region by controlling the solidification conditions at the end of the weld. The controlled heat flow is achieved by adjusting the parameters of both welding processes involved, the laser beam as well as gas metal arc welding (GMAW) process. Experimental investigations were carried out on 12 mm to 15 mm thick tube sections. The influence of process parameters such as the laser ramp time, the change in magnification scale and the defocusing of the laser beam on the solidifi-cation conditions at the end of the circumferential weld was investigated to find an optimum strategy for ramping out the process energy. Within the framework of the experimental studies, it was demonstrated that defocusing the laser beam in the range between 60 mm and 100 mm over a short run-out area of the weld of approximately 15 mm led to a significantly better weld formation in the overlap area. A favourable cup-shaped weld shape could be achieved without a tendency to crack. The laser optics with a motor-driven lens system made it possible to increase the laser beam diameter without changing the position of the GMAW arc relative to the component surface. KW - Weld defects KW - Hybrid welding KW - Laser beam welding KW - Pipe manufacturing KW - Gas shielded arc welding PY - 2021 VL - 20 IS - 4 SP - 334 EP - 339 PB - DVS Media AN - OPUS4-54665 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Üstündag, Ö. A1 - Gook, S. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Mechanical Properties of Single-pass Hybrid Laser Arc Welded 25 mm Thick-walled Structures Made of Fine-grained Structural Steel N2 - The presented study deals with the performing and mechanical testing of single pass hybrid laser-arc welds (HLAW) on 25 mm thick plates made of steel grade S355J2. One of the challenges have to be solved at full penetration HLAW of thick plates is the drop formation occurring due to the disbalances of the forces acting in the keyhole and on the melt pool surface. Such irregularities mostly limit the use of high-power laser beam welding or HLAW of thick-walled constructions. To overcome this problem, an innovative concept of melt pool support based on generating Lorentz forces in the weld pool is used in this work. This method allows to perform high quality welds without sagging even for welding of 25 mm thick plates in flat position at a welding speed of 0.9 m min-1. For the obtain of full penetrated welds a laser beam power of 19 kW was needed. A high V-impact energy of up to 160 J could be achieved at the test temperature of 0 °C. Even at the most critical part in the weld root an impact energy of 60 J in average could be reached. The tensile strength of the weld reaches that of the base material. An introduce of the HLAW process with electromagnetic support of the melt pool in the industrial practice is an efficient alternative to the time- and cost-intensive arc-based multi-layer welding techniques which are established nowadays for joining of thick-walled constructions. KW - Mechanical Properties KW - Hybrid Laser Arc Welding KW - Thick-walled Structures KW - Fine-grained Steel PY - 2019 DO - https://doi.org/10.1016/j.promfg.2019.08.016 SN - 2351-9789 VL - 36 SP - 112 EP - 120 PB - Elsevier B.V. AN - OPUS4-48969 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael A1 - Üstündag, Ö. A1 - Gook, S. A1 - Gumenyuk, Andrey T1 - Mechanical Properties of Single-pass Hybrid Laser Arc Welded 25 mm Thick-walled Structures Made of Fine-grained Structural Steel N2 - The presented study deals with the performing and mechanical testing of single pass hybrid laser-arc welds (HLAW) on 25 mm thick plates made of steel grade S355J2. One of the challenges have to be solved at full penetration HLAW of thick plates is the drop formation occurring due to the disbalances of the forces acting in the keyhole and on the melt pool surface. Such irregularities mostly limit the use of high-power laser beam welding or HLAW of thick-walled constructions. To overcome this problem, an innovative concept of melt pool support based on generating Lorentz forces in the weld pool is used in this work. This method allows to perform high quality welds without sagging even for welding of 25 mm thick plates in flat position at a welding speed of 0.9 m min-1. For the obtain of full penetrated welds a laser beam power of 19 kW was needed. A high V-impact energy of up to 160 J could be achieved at the test temperature of 0 °C. Even at the most critical part in the weld root an impact energy of 60 J in average could be reached. The tensile strength of the weld reaches that of the base material. An introduce of the HLAW process with electromagnetic support of the melt pool in the industrial practice is an efficient alternative to the time- and cost-intensive arc-based multi-layer welding techniques which are established nowadays for joining of thick-walled constructions. T2 - 17th Nordic Laser Materials Processing Conference - NOLAMP17 CY - Trondheim, Norway DA - 27.08.2019 KW - Full Penetration KW - Hybrid Laser Arc Welding KW - Electromagnetic Weld Pool Support KW - Thick Materials PY - 2019 AN - OPUS4-48977 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Simón Muzás, Juan A1 - Brunner-Schwer, Christian A1 - Hilgenberg, Kai A1 - Rethmeier, Michael T1 - Mechanical properties of laser welded joints of wrought and heat treated PBF LB/M Inconel 718 parts depending on build direction N2 - Laser-based Powder Bed Fusion of Metal (PBF-LB/M) is a broadly used metal additive manufacturing (AM) method for fabricating complex metallic parts, whose sizes are however limited by the build envelope of PBF-LB/M machines. Laser welding arises as a valid joining method for effectively integrating these AM parts into larger assemblies. PBF-LB/M components must usually be stress-relieved before they can be separated from the build plate. An additional heat treatment can be beneficial for obtaining homogeneous mechanical properties across the seam or for the formation of desired precipitations in nickel-based-alloys. Therefore, the tensile performance of laser welded hybrid (AM/wrought) and AM-AM tensile samples of Inconel 718 is examined after undergoing three different heat treatments and considering three relevant build directions. It can be shown that the build orientation is an influencing factor on weld properties even after two applied heat treatments. T2 - Lasers in Manufacturing LiM 2023 CY - Munich, Germany DA - 26.09.2023 KW - Inconel 718 KW - Laser welding KW - PBF/LB-M KW - Hybrid components KW - Heat treatments KW - Build direction KW - Tensile performance PY - 2023 SP - 1 EP - 10 PB - Proceedings Lasers in Manufacturing 2023 CY - München AN - OPUS4-58394 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liu, X. C. A1 - Wu, Chuan Song A1 - Rethmeier, Michael A1 - Pittner, Andreas T1 - Mechanical properties of 2024-T4 aluminium alloy joints in ultrasonic vibration enhanced friction stir welding N2 - Ultrasonic vibration enhanced friction stir welding (UVeFSW) is a recent modification of conventional friction stir welding (FSW), which transmits ultrasonic vibration directly into the localized area of the workpiece near and ahead of the rotating tool. In this study, a high strength aluminium alloy (2024-T4) was welded by this process and conventional FSW, respectively. Then tensile tests, microhardness tests and fracture surface analysis were performed successively on the welding samples. The tests results reveal that ultrasonic vibration can improve the tensile strength and the elongation of welded joints. The microhardness of the stir zone also increases. KW - Ultrasonic vibration KW - Friction stir welding KW - Mechanical properties PY - 2013 UR - https://www.researchgate.net/publication/286735810_Mechanical_properties_of_2024-T4_aluminium_alloy_joints_in_ultrasonic_vibration_enhanced_friction_stir_welding VL - 22 IS - 4 SP - 8 EP - 13 AN - OPUS4-40773 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Javaheri, E. A1 - Lubritz, J. A1 - Graf, B. A1 - Rethmeier, Michael T1 - Mechanical Properties Characterization of Welded Automotive Steels N2 - Among the various welding technologies, resistance spot welding (RSW) and laser beam welding (LBW) play a significant role as joining methods for the automobile industry. The application of RSW and LBW for the automotive body alters the microstructure in the welded areas. It is necessary to identify the mechanical properties of the welded material to be able to make a reliable statement about the material behavior and the strength of welded components. This study develops a method by which to determine the mechanical properties for the weldment of RSW and LBW for two dual phase (DP) steels, DP600 and DP1000, which are commonly used for the automotive bodies. The mechanical properties of the resistance spot weldment were obtained by performing tensile tests on the notched tensile specimen to cause an elongation of the notched and welded area in order to investigate its properties. In order to determine the mechanical properties of the laser beam weldment, indentation tests were performed on the welded material to calculate its force-penetration depth-curve. Inverse numerical simulation was used to simulate the indentation tests to determine and verify the parameters of a nonlinear isotropic material model for the weldment of LBW. Furthermore, using this method, the parameters for the material model of RSW were verified. The material parameters and microstructure of the weldment of RSW and LBW are compared and discussed. The results show that the novel method introduced in this work is a valid approach to determine the mechanical properties of welded high-strength steel structures. In addition, it can be seen that LBW and RSW lead to a reduction in ductility and an increase in the amount of yield and tensile strength of both DP600 and DP1000. KW - Mechanical property KW - Laser beam welding KW - Dual phase steel KW - Resistance spot welding PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-502269 DO - https://doi.org/10.3390/met10010001 VL - 10 IS - 1 SP - 1 EP - 20 PB - MDPI AN - OPUS4-50226 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Javaheri, E. A1 - Pittner, Andreas A1 - Graf, B. A1 - Rethmeier, Michael T1 - Mechanical properties characterization of reisstance spot welded DP1000 steel under uniaxial tensile tests N2 - Resistance spot welding (RSW) is widely used in the automotive industry as the main joining method. Generally, an automotive body contains around 2000 to 5000 spot welds. Therefore, it is of decisive importance to characterize the mechanical properties of these areas for the further optimization and improvement of an automotive body structure. The present paper aims to introduce a novel method to investigate the mechanical properties and microstructure of the resistance spot weldment of DP1000 sheet steel. In this method, the microstructure of RSW of two sheets was reproduced on one sheet and on a bigger area by changing of the welding parameters, e. g. welding current, welding time, electrode force and type. Then, tensile tests in combination with digital Image correlation (DIC) measurement were performed on the notched tensile specimens to determine the mechanical properties of the weld metal. The notch must be made on the welded tensile specimen to force the fracture and elongation on the weld metal, enabling the characterization of its properties. Additionally, the parameters of a nonlinear isotropic material model can be obtained and verified by the simulation of the tensile specimens. The parameters obtained show that the strength of DP1000 steel and the velocity of dislocations for reaching the Maximum value of strain hardening, are significantly increased after RSW. The effect of sample geometry and microstructural inhomogeneity of the welded joint on the constitutive property of the weld metal are presented and discussed. KW - Mechanical properties KW - resistance spot welding KW - dual phase steel KW - digital image correlation PY - 2019 VL - 61 IS - 6 SP - 527 EP - 532 PB - Carl Hanser Verlag CY - München AN - OPUS4-48296 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stankevich, S. A1 - Gumenyuk, Andrey A1 - Straße, Anne A1 - Rethmeier, Michael ED - Reisgen, U. ED - Schmidt, M. ED - Zaeh, M. ED - Rethmeier, Michael T1 - Measurement of thermal cycle at multi-pass layer build-up with different travel path strategies during DLMD process N2 - The shape of the parts, created by the technology of direct laser metal deposition (DLMD), is influenced by various parameters, for example, the power and diameter of the laser source spot. The contribution of energy from the laser affects the temperature distribution in the formed layers. The changing temperature in the working area entails a Change in the geometry of the layers and affects the stability of the process. In this paper, experiments on the measurement of temperature cycles in the DLMD process with different directions of the filling track are carried out. An infrared camera was used to measure thermal cycles. The calibration of the acquired data (i.e. correspondence table between the intensity of thermal radiation of the material and the absolute temperature) was done with help of two-color pyrometer ex situ and in situ measurements. The experiments are carried out on two materials 316L and Inconel 718. The effect of the maximum temperature on the layer height is shown, and thermal cycles in the formation of layers for different filling strategies are presented. T2 - Laser in Manufacturing Conference 2019 CY - Munich, Germany DA - 24.06.2019 KW - Thermography KW - Direct Laser Metal Deposition PY - 2019 SP - 1 EP - 9 AN - OPUS4-48716 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Artinov, Antoni A1 - Karkhin, V. A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Mathematical modeling of the geometrical differences between the weld end crater and the steady-state weld pool N2 - The geometrical characteristics of the weld end crater are commonly used for the validation of numerical results in welding simulation. A semi-analytical model calculating the cooling stage of the welding process after the moving energy source is turned off has been developed. A solution for various combinations of heat sources and workpieces has been found. The theoretical limits for the heat transfer of the absorbed energy during cooling in a thin plate and a semi-infinite body were studied. It is shown that after turning off the energy source, an additional melting of the base material in longitudinal direction may occur. The developed technique is applied to complete-penetration keyhole laser beam welding of a 2 mm thick austenitic chromium-nickel 316L steel plate at a welding speed of 20 mm/s and a laser power of 2.3 kW. The results show a theoretical increase of the weld end crater length in comparison to the length of the steady-state weld pool of up to 19 %. A shift of the centre of the end crater, in which the solidification of the liquid metal ends, towards the tail of the end crater relative to the axis of the heat source at the time of its termination, was computed. The speed and the direction of crystallization of the molten material in the weld pool and the end crater were found to be different. A good agreement between the computational results and the welding experiments was achieved. T2 - ICALEO 2019 - The International Congress on Applications of Lasers & Electro-Optics (Proceedings) CY - Orlando, FL USA DA - 07.10.2019 KW - Keyhole mode welding KW - Weld pool shape KW - End-crater KW - Heat conduction PY - 2019 UR - http://icaleo.conferencespot.org/2019-proceedings?qr=1 SN - 978-1-940168-1-42 SP - 1 EP - 8 AN - OPUS4-49344 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Artinov, Antoni A1 - Karkhin, V. A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Mathematical modeling of the geometrical differences between the weld end crater and the steady-state weld pool N2 - The geometrical characteristics of the weld end crater are commonly used as a means of validating numerical results in welding simulations. In this paper, an analytical model is developed for calculating the cooling stage of the welding process after the moving energy source is turned off. Solutions for various combinations of heat sources and heated bodies are found. It is shown that after turning off the Energy source, additional melting of the base material in the longitudinal direction may occur due to the overheated liquid metal. The developed technique is applied to complete-penetration keyhole laser beam welding of 2 mm thick austenitic stainless-steel plate 316L at a Welding speed of 20 mm/s and a laser power of 2.3 kW. The results show a theoretical increase in the weld end crater length of up to 19% compared to the length of the steady-state weld pool. It is found that at the moment of switch off, the weld end crater center, where solidification of the liquid metal ends, is shifted from the heat source axis toward the weld pool tail. The solidification rate and the direction of crystallization of the molten material during the welding process and those in the weld end crater differ significantly. A good agreement between the computational results and the welding experiments is achieved. KW - Weld end crater KW - Steady-state weld pool KW - Mathematical modeling KW - Solidification KW - Laser beam welding PY - 2020 DO - https://doi.org/10.2351/7.0000068 VL - 32 IS - 2 SP - 022024-1 EP - 022024-6 PB - AIP Publishing AN - OPUS4-50767 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Frei, J. A1 - Alexandrov, B. A1 - Rethmeier, Michael T1 - Low heat input gas metal arc welding for dissimilar metal weld overlays part III: hydrogen-assisted cracking susceptibility N2 - Dissimilar metal weld overlays of nickel-base alloys on low-alloy steel components are commonly used in the oil and gas, petrochemical, and power generation industries to provide corrosion and oxidation resistance in a wide range of service Environments and temperatures. Traditionally, dissimilar weld overlays are produced using cold or hot wire gas tungsten arc welding. This study aims to identify and evaluate potential advantages of low heat input gas metal arc welding processes over the conventional gas tungsten arc welding in the production of such overlays. Parts I and II of this publication series described characteristics of the heat-affected zone and the transition zone region of alloy 625 on grade 22 steel overlays. These results indicate a good resistance against hydrogen-assisted cracking, which is being verified within this third part of the publication series. To determine the hydrogen-assisted cracking susceptibility, welded samples are tested using the delayed hydrogen-assisted cracking test. Fractography is performed using scanning electron microscopy along with energy dispersive spectroscopy. The results confirm the suitability and efficiency of low heat input gas metal arc welding for dissimilar weld overlays. Variation of the postweld heat treatment procedure bears potential for improvement in this respect. KW - Low heat input GMA welding KW - Dissimilar metal weld overlays KW - Coarse-grained heat-affected zone KW - Grain size KW - Microstructure KW - Fusion zone KW - Nickel alloys PY - 2019 DO - https://doi.org/10.1007/s40194-018-0674-7 VL - 63 IS - 3 SP - 591 EP - 598 PB - Springer AN - OPUS4-48096 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Frei, J. A1 - Alexandrov, B. T. A1 - Rethmeier, Michael T1 - Low heat input gas metal arc welding for dissimilar metal weld overlays part II: the transition zone N2 - Dissimilar metal weld overlays (DMWOL) of nickel base alloys on low alloy steel components are commonly used in the oil and gas, petrochemical, and power generation industries to provide corrosion and oxidation resistance in a wide range of service environments and temperatures. Traditionally, dissimilar weld overlays are produced using cold or hot wire gas tungsten arc welding. This study aims to identify and evaluate potential advantages of low heat input gas metal arc welding processes over the conventional gas tungsten arc welding in the production of dissimilar weld overlays. In order to evaluate the quality of these overlays regarding resistance against hydrogen-assisted cracking, their transition zone region is investigated in this part of the publication series. Metallurgical characterization, including energy-dispersive x-ray spectroscopy, is performed on Alloy 625/grade 22 steel overlays. The transition zone is characterized by a narrow planar growth zone and steep compositional gradients from the fusion boundary towards the weld metal. Evidence of low carbon contents in the planar growth zone, as well as for carbide precipitation in the cellular growth zone was found. The microstructure in the transition zone region of the fusion zone shows characteristics known to be suitable for good resistance against hydrogen embrittlement. KW - Low heat input Gma welding KW - Dissimilar metal weld overlays KW - Coarse grained heat affected zone KW - Grain size KW - Microstructure KW - Fusion zone, nickel alloys PY - 2018 DO - https://doi.org/10.1007/s40194-017-0539-5 VL - 62 IS - 2 SP - 317 EP - 324 PB - Springer CY - Heidelberg, Germany AN - OPUS4-44721 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Frei, J. A1 - Rethmeier, Michael A1 - Alexandrov, B. T. T1 - Low heat input gas metal arc welding for dissimilar metal weld overlays part I: the heat-affected zone N2 - Dissimilar metal weld overlays of nickel base alloys on low alloy steel components are commonly used in the oil and gas, petro-chemical, and power generation industries to provide corrosion and oxidation resistance in a wide range of service environments and temperatures. Traditionally, weld overlays are produced using cold or hot wire gas tungsten arc welding (GTAW). Potential advantages of cold metal Transfer (CMT) welding, a low heat input gas metal arc welding process, over the conventional GTAW in production of weld overlays were evaluated. Metallurgical characterization was performed on CMT overlays of Alloy 625 filler metal on Grade 11 and Grade 22 steels. Significant grain refinement was found in the high temperature HAZ compared to the traditional coarse-grained HAZ in arc welding. Evidences of incomplete carbide dissolution, limited carbon diffusion, and incomplete transformation to austenite were also found. These phenomena were related to high heating and cooling rates and short dwell times of the high-temperature HAZ in austenitic state. Tempering effects in the steel HAZ were identified, showing a potential for development of CMT temperbead procedures. Based on the results of this study, the steel HAZ regions in CMT overlays were classified as high-temperature HAZ and intercritical HAZ. KW - Clad steels KW - Nickel alloys KW - Low alloy steels KW - GMA surfacing KW - DIP transfer KW - Coarse-grained heat-affected zone KW - Microstructure PY - 2016 DO - https://doi.org/10.1007/s40194-016-0306-z SN - 0043-2288 SN - 1878-6669 VL - 60 IS - 3 SP - 459 EP - 473 PB - Springer CY - Heidelberg, Germany AN - OPUS4-36377 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Straße, Anne A1 - Üstündag, Ömer A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael ED - Schmidt, M. ED - Vollertsen, F. ED - Govekar, E. T1 - LMD coatings as filler material for laser beam welded 30 mm thick plates N2 - The development of high energy laser sources enables single-pass welds of thick plates up to 30 mm, but often additional materials are needed to influence the properties of the weld seams. However, the homogenous distribution of filler materials in form of e.g. electrodes is only possible up to 7 mm while the elements are only traceable up to a depth of 14 mm. To overcome this problem a two-step process is used where first the edges of the weld partners are coated with the filler material by laser metal deposition (LMD) and afterwards are welded by laser beam. Single-pass welds with electromagnetic weld pool support of 30 mm thick S355 J2+N-plates with austenitic AISI 316L-coatings were investigated as well as the influence of the coatings to the penetration depth of the laser beam without electromagnetic weld pool support in double-sided joints. The weld seams were tested by X-ray inspection and cross sections. T2 - 11th CIRP Conference on Photonic Technologies [LANE 2020] CY - Online meeting DA - 07.09.2020 KW - Penetration depth KW - Laser metal deposition (LMD) KW - Laser beam welding KW - Filler material distribution PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-512790 DO - https://doi.org/10.1016/j.procir.2020.09.055 SN - 2212-8271 VL - 94 SP - 293 EP - 297 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-51279 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Life Cycle Assessment of Fusion Welding Processes - A Case Study of Resistance Spot Welding Versus Laser Beam Welding N2 - The high amount of resource consumption of fusion welding processes offers the potential to reduce their environmental impact. While the driving forces are known froma qualitative perspective, the quantitative assessment of the crucial parameters is not a trivial task. Therefore, herein, a welding-specific methodology to utilize life cycle assessment as a tool for evaluating the environmental impact of fusion welding processes is presented. In this context, two welding processes, resistance spot welding and laser beam welding, are analyzed for two different use cases. These comprise the welding of shear test specimens and a cap profile made of electrogalvanized sheets of DC 05þ ZE (1.0312) as representative of an automotive application. For both welding processes, the main influences on the resulting environmental impact categories are evaluated and compared. The requirements for ecological efficient welding processes are discussed and implemented. KW - Resistance spot welding KW - Carbon dioxide footprint KW - Environmental impact categories KW - Laser beam welding KW - Life cycle assessment PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-566458 DO - https://doi.org/10.1002/adem.202101343 SN - 1438-1656 VL - 24 IS - 6 SP - 1 EP - 14 PB - Wiley-VCH CY - Weinheim AN - OPUS4-56645 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Winterkorn, René A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Lichtbogenbasierte additive Fertigung dickwandiger Strukturen aus einer höherfesten Al-Mg-Si-Aluminiumlegierungen N2 - Die lichtbogenbasierte, additive Fertigung ist dank hoher erreichbarer Aufbauraten und nahezu uneingeschränktem Bauraum zur Fertigung großvolumiger Bauteile prädestiniert. Die Kombination etablierter Maschinenkomponenten aus Robotertechnik, Schweißtechnik und Sensorik ermöglicht den präzisen schichtweisen Materialauftrag. Die Wirkmechanismen zwischen Prozessparametern und den daraus resultierenden mechanisch-technologischen Eigenschaften der additiv gefertigten Bauteile stellen eine Herausforderung dar. Dies gilt insbesondere auch für dickwandige Bauteile. Bei der Fertigung von Bauteilen aus höherfesten Al-Mg-Si-Aluminiumlegierungen ist aufgrund der hohen Anfälligkeit für Erstarrungsrisse und der Neigung zu wasserstoffinduzierter Porosität im besonderen Maße auf das Temperaturregime und die gewählte Aufbaustrategie zu achten. Der Einfluss der Prozessparameter auf die Bauteilqualität wurde durch die Analyse der Größe und Verteilung von Poren sowie der resultierenden Festigkeit untersucht. Darüber hinaus wurde der Einfluss einer Wärmenachbehandlungsstrategien auf das Festigkeitsverhalten analysiert. Es konnte gezeigt werden, dass dickwandige Strukturen aus höherfesten Al-Mg-Si-Aluminiumlegierungen mit mechanischen Kennwerten im Bereich des Referenzmaterials mittels MSGLichtbogenverfahren additiv gefertigt werden können. T2 - Additive Fertigung – Werkstoffe – Prozesse – Wärmebehandlung 2022 CY - Bremen, Germany DA - 29.06.2022 KW - WAAM KW - Al-Mg-Si-Legierungen KW - Porosität KW - Wärmenachbehandlung KW - Mechanisch technologische Kennwerte PY - 2022 SP - 169 EP - 181 PB - Arbeitsgemeinschaft Wärmebehandlung und Werkstofftechnik e. V. CY - Bremen AN - OPUS4-56673 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rethmeier, Michael A1 - Finkbeiner, M. T1 - Licht ist grüner als Strom N2 - Laserschweißen gegen Widerstandspunktschweißen: Die Die Entscheidung fällt am Flansch. Beide Verfahren sind sehr schnell und hoch automatisierbar. KW - Laserschweißen KW - Widerstandspunktschweißen PY - 2017 VL - 24 SP - 6 EP - 6 AN - OPUS4-40413 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fritzsche, André A1 - Avilov, Vjaceslav A1 - Bachmann, Marcel A1 - Gumenyuk, Andrey A1 - Hilgenberg, Kai A1 - Rethmeier, Michael T1 - Laserstrahlschweißen dicker Stahlplatten mit elektromagnetischer Schmelzbadunterstützung N2 - Das bislang zur Vermeidung unzulässiger Wurzelüberhöhungen beim Laserstrahlschweißen von Aluminiumlegierungen bzw. austenitischem Stahl eingesetzte Verfahren der elektromagnetischen Schmelzbadstütze konnte innerhalb der vorliegenden Untersuchung erfolgreich zur Kompensation des hydrostatischen Druckes von ferromagnetischen Stählen übertragen werden. Es wurden dabei Laserstrahlschweißversuche in PA-Position an bis zu 20 mm dickem Duplexstahl 1.4462 sowie Baustahl S235JR durchgeführt. Unter konstanten Schweißparametern wurden Durchschweißungen generiert. Dem hydrostatischen Druck wurde unter Verwendung der Technologie zur elektromagnetischen Schmelzbadunterstützung durch Variation der Oszillationsfrequenz und der AC-Leistung des Magnetsystems entgegengewirkt. Zunächst konzentrierten sich die Versuche auf den Duplexstahl 1.4462, welcher jeweils aus 50 % Ferrit und Austenit besteht. Hierbei konnte festgestellt werden, dass zur idealen Kompensation von 15 mm bei einer Frequenz von 1,7 kHz eine AC-Leistung von 1,6 kW erforderlich ist, die Schweißnähte aber bereits bei einer AC-Leistung von ca. 0,8 kW in die Bewertungsgruppe B der DIN EN ISO 13919-1:1996-09 eingeordent werden können. Zur idealen Kompensation des hydrostatischen Druckes bei 20 mm dickem Duplexstahl war eine um 20 % höhere AC-Leistung notwendig. Im Anschluss an die Versuche mit dem Duplexstahl wurden die Untersuchungen auf bis zu 20 mm dicke Proben aus Baustahl S235JR erweitert. Für 15 mm konnten die Schweißnähte bei einer Frequenz von 1,7 kHz ab einer AC-Leistung von 1,3 kW in die Bewertungsgruppe B eingeordnet werden. Zur idealen Kompensation von 20 mm dickem Baustahl war eine AC-Leistung von 1,6 kW bei einer Frequenz von 636 Hz nötig. Mit steigender AC-Leistung konnte in allen Versuchsreihen eine sukzessive Verringerung der Wurzelüberhöhung demonstriert werden. T2 - Assistentenseminar 2016 der Wissenschaftlichen Gesellschaft Fügetechnik e.V. im DVS CY - Paewesin, Germany DA - 05.09.2016 KW - Elektromagnetische Schmelzbadunterstützung KW - Laserstrahlschweißen KW - Ferromagnetischer Stahl PY - 2018 SN - 978-3-96144-025-2 VL - 339 SP - 38 EP - 43 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-44302 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jokisch, T. A1 - Gook, S. A1 - Marko, A. A1 - Üstündag, Ömer A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Laserstrahlschweißen additiv gefertigter Bauteile: Einsetzbarkeit bestehender Bewertungsvorschriften N2 - Bei der additiven Fertigung im Pulverbett ist die Bauteilgröße durch den Bauraum begrenzt. Das Verbindungsschweißen additiv gefertigter Teile bietet eine Möglichkeit diese Größenbegrenzung aufzuheben. Aufgrund des spezifischen Spannungs- und Gefügezustands im additiv aufgebauten Teil ist jedoch unklar, inwiefern bestehende Bewertungsvorschriften des Verbindungsschweißens auch für Schweißnähte an additiv gefertigten Bauteilen geeignet sind. Dies wird anhand des Laserstrahlschweißens additiv gefertigter Rohrverbindungen untersucht. Die Schweißnähte werden mittels visueller Prüfung, metallografischer Untersuchungen sowie Computertomografie ausgewertet. Die festgestellten Fehlerarten sind vergleichbar zu konventionellen Bauteilen. Dies ist ein Indikator dafür, dass bestehende Bewertungsvorschriften die möglichen auftretenden Defekte auch für Schweißnähte an additiven Bauteilen abbilden. KW - Schweißunregelmäßigkeiten KW - Additive Fertigung KW - Laserstrahlschweißen KW - Schweißeignung PY - 2021 VL - 73 IS - 3 SP - 132 EP - 137 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-53575 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Üstündag, Ömer A1 - Bakir, Nasim A1 - Brunner-Schwer, C. A1 - Knöfel, F. A1 - Gook, S. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Laserstrahlhybridschweissen von Türmen für Windkraftanlagen Ökonomische und ökologische Vorteile N2 - Das Laserstrahlhybridschweißen ist beim Schweißen von Türmen für Windkraftanlagen eine Alternative zum Unterpulverschweißen von Dickblechen in Mehrlagentechnik und bietet hier ökonomische und ökologische Vorteile. Der industrielle Einsatz des Verfahrens ist jedoch durch prozessspezifische Herausforderungen eingeschränkt. Die im Beitrag beschriebene kontaktlose elektromagnetische Badstütze dient zur Erweiterung des Verfahrenspotenzials im Dickblechbereich >15 mm. KW - Elektromagnetische Badstütze KW - Laserhybridschweißen KW - Windkraftanlagen KW - Ökonomische und ökologische Vorteile PY - 2022 VL - 7 SP - 340 EP - 347 PB - DVS Media GmbH AN - OPUS4-56372 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kampffmeyer, D. A1 - Wolters, M. A1 - Raute, J. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Laserstrahlauftragschweißen – Einfluss von Schutzgasgemischen auf die Bauteilqualität N2 - Im Additive Manufacturing Verfahren Directed Energy Deposition (DED) wird bei der Verarbeitung von Werkzeugstahl in der Regel reines Argon als Schutzgas verwendet. Dabei kann die Verwendung von speziellen Schutzgasgemischen, auch bei geringen Anteilen zugemischter Gase, durchaus die Bauteilqualität positiv beeinflussen. In Vorarbeiten der Messer SE & Co. KGaA zeigte ein gewisser Sauerstoffanteil im Schutzgas die Tendenz, den Flankenwinkel von Schweißspuren beim DED zu verbessern. In der vorliegenden Studie wurde daher detailliert untersucht in wie weit unterschiedliche Schutzgasgemische einen Einfluss auf die Qualität sowie die geometrischen Eigenschaften der additiv gefertigten Strukturen des Werkzeugstahls 1.2709 beim Laser-DED ausüben. Es erfolgten zunächst Testschweißungen in Form von Einzelspuren mit unterschiedlichen Gemischen aus dem Basisschutzgas Argon mit geringen Anteilen verschiedener Gase. Dabei wurde der Einfluss der Zusätze auf die Spurgeometrie und Aufbauqualität untersucht. Auf Basis dieser Vorversuche wurde eine Auswahl vielversprechender Gasgemische getroffen und Detailuntersuchungen in Form von Spuren, Flächen und Quadern unter Zugabe verschiedener Mengen an Zusätzen durchgeführt. Zur Bewertung des Einflusses der Schutzgasbeimengungen wurden der Flankenwinkel, die Porosität und das Gefüge der Proben anhand metallografischer Schliffe untersucht. Es zeigte sich, dass eine Zugabe von geringen Anteilen an Zusätzen zunächst zu einer Vergrößerung des Flankenwinkels im Vergleich zu reinem Argon führt. Mit steigendem Anteil der Gase nimmt dieser Winkel jedoch ab. So kann je nach Menge des zugesetzten Gases eine individuelle Benetzung des aufgetragenen Materials an der Oberfläche erreicht werden. Auch die Porosität ließ sich durch Schutzgasgemische beeinflussen und zeigt ein abweichendes Verhalten im Vergleich zu reinem Argon. T2 - DVS Congress 2023 Große Schweißtechnische Tagung DVS CAMPUS CY - Essen, Germany DA - 11.09.2023 KW - Laser-Pulver-Auftragschweißen KW - DED-LB KW - Schutzgas KW - Additive Fertigung PY - 2023 SN - 978-3-96144-230-0 SP - 505 EP - 511 PB - DVS-Media AN - OPUS4-58585 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gook, S. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael ED - Schneider, G. ED - Zschech, E. ED - Petzow, G. T1 - Laserstrahl-MSG-Hybridschweißen von Rohren aus Hochfestem Stahl API-X80/ -X100 N2 - Das Laser-MSG-Hybridschweißverfahren führt bei untersuchten hochfesten Pipelinestählen API X80 und X120 reproduzierbar zu Schweißverbindungen mit anforderungsgerechten Zähigkeitseigenschaften. Eine metallurgische Beeinflussung der Schweißnahtzähigkeit ist durch eine gezielte Auswahl des Zusatzwerkstoffes möglich, wobei die maximale Eindringtiefe des Zusatzwerkstoffes in die Tiefe der Laserhybridnaht zu beachten ist. Die maximal erzielbare Eindringtiefe des Zusatzwerkstoffes ist auf ca. 14 mm begrenzt. Die eingesetzte Art des MSG-Lichtbogens hatte keinen erkennbaren Einfluss auf die Aufmischung im Laseranteil der Laserhybridnaht. Die besseren Ergebnisse der Kerbschlagzähigkeit konnten mit Metallpulverdrähten erreicht werden. Mit den erzielten gemittelten Werten der Schlagarbeit: ca. 200 J bei -60°C für X80 und ca. 53 J bei -40°C für X120 werden Anforderungen der Norm API 5L und DIN EN 10208-2 für die beiden untersuchten Grundwerkstoffe erfüllt. T2 - 49. Metallographie-Tagung CY - Dresden, Germany DA - 16.09.2015 KW - Hochfester Stahl KW - Laserstrahl-MSG-Hybridschweißen PY - 2015 SN - 978-3-88355-410-5 VL - 47 SP - 139 EP - 144 PB - Inventum CY - Sankt Augstin AN - OPUS4-44419 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael A1 - Gook, S. A1 - Gumenyuk, Andrey T1 - Laserstrahl-Hybridschweißen für Rohranwendungen N2 - Mechanische Eigenschaften der laserhybridgeschweißten Schweißverbindungen von hochfesten niedriglegierten Stählen erfüllen die Anforderungen der geltenden Normen Eindringtiefe des Zusatzwerkstoff bis ca. 12 mm Halborbitales Schweißen an 36” Rohren mit einer Wandstärke von 16 mm bei einer Schweißgeschwindigkeit von bis zu 2,2 m/min und Laserleistung von 19 kW technisch möglich Rissfreie Schweißverbindungen an Präzisionsrohren können durch eine geeignete Schweißparameterauswahl mittels Laser-Hybridverfahren hergestellt werden T2 - IW-Kolloquium CY - Hannover, Germany DA - 07.05.2014 KW - Laserstrahlquelle KW - Hybridprozesse KW - MSG-Schweißen PY - 2014 AN - OPUS4-38338 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Spranger, Felix A1 - Hilgenberg, Kai A1 - Rethmeier, Michael T1 - Laserimplantation von TiB2-Partikeln in X153CrMoV12 Kaltarbeitsstahl und Ihr Einfluss auf die Materialeigenschaften N2 - Die Laserimplantation erlaubt die Herstellung verschleißbeständiger, erhabener Mikrostrukturen (Implants) auf Stahloberflächen durch ein diskontinuierliches Dispergieren von keramischen Partikeln mittels gepulster Laserstrahlung. Durch die flexible Anordnung separierter Implants zu komplexen Mustern erlaubt das Verfahren eine gezielte Oberflächenstrukturierung zur Beeinflussung des Reibungs- und Verschleißverhaltens. Insbesondere erwies sich Titandiborid (TiB2) als Implantationsmaterial für geeig-net, da eine Manipulation der Implantgeometrie in einem breiten Bereich vorgenommen werden konnte, ohne dass Materialdefekte wie Risse oder Poren auftraten. Ziel der Untersuchungen war es, den Einfluss implantierter TiB2-Partikel auf die Materialeigenschaften von X153CrMoV12 zu ermitteln. Hierfür wurden im Rahmen der Arbeit die Laserparameter (Pulsleistung und -dauer) in einem breiten Parameterfeld variiert und vergleichende Untersuchungen an TiB2 implan-tierten Zonen sowie an punktuell umschmelzstrukturierten Zonen durchgeführt. Die Ergebnisse zeigen, dass eine reine Umschmelzstrukturierung zu einer deutlichen Reduktion der Oberflächenhärte aufgrund erhöhter Restaustenitgehalte (γR) führt. Im Gegensatz dazu führt das Laserimplantieren von TiB2-Partikeln zu einer deutlichen Härtesteigerung in den kuppel- oder ringförmigen Implants. Härtewerte von bis zu 1800 HV1 resultieren aus dispergierten TiB2-Primärpartikeln sowie in-situ ausgeschiedenen Se-kundärphasen, durch die der Restaustenitanteil zudem deutlich reduziert wird. T2 - 39. Assistentenseminar Füge- und Schweißtechnik CY - Eupen, Belgium DA - 12.09.2018 KW - Laserimplantation KW - TiB2 KW - AISI D2 KW - Laserdispergieren PY - 2019 SN - 978-3-96144-070-2 VL - Band 356 SP - 51 EP - 59 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-48751 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gumenyuk, Andrey A1 - Üstündag, Ö. A1 - Gook, S. A1 - Rethmeier, Michael T1 - Laserhybridschweißen von dickwandigen Stählen mit elektromagnetischer Schmelzbadunterstützung N2 - Die steigenden Anforderungen in Hinsicht auf Sicherheitsfaktoren von gefügten Bauteilen führen zu einer Zunahme der zu schweißenden Bauteildicken. Das Laserstrahl-Lichtbogen-Hybridschweißverfahren – verbreitet im industriellen Einsatz vor allem im Schiffs- und Windkraftanlagenbau – ermöglicht das einlagige Fügen von dickwandigen Strukturen. Eine Herausforderung stellt das Schweißen von dickwandigen Bauteilen mit reduzierter Geschwindigkeit in Wannenlage (PA-Position) da. Sie ist aufgrund des erhöhten hydrostatischen Druckes und die daraus resultierenden Tropfenbildung an der Wurzelseite bedingt realisierbar. Die im Rahmen dieser Studie eingesetzte elektromagnetische Schmelzbadunterstützung wirkt dem gravitationsbedingten Austropfen der Schmelze entgegen und kompensiert den hydrostatischen Druck. Dabei werden unterhalb der Schweißzone mit Hilfe eines extern angelegten oszillierenden Magnetfeldes Wirbelströme im Werkstück induziert, die eine nach oben gerichtete Lorentzkraft erzeugt. Die Lorentzkraft wirkt dem hydrostatischen Druck entgegen und stellt einen sicheren Schweißprozess ohne Tropfenbildung dar. Mit dem Hybridschweißverfahren mithilfe der elektromagnetischen Schmelzbadunterstützung gelingt es mit einem 20-kW Faserlaser bis zu 30 mm dicke Bleche in einer Lage zu schweißen. Bei 25 mm dicken einlagig geschweißten Platten aus S355 konnte ein Spalt bis 1 mm und ein Kantenversatz bis zu 2 mm sicher überbrückt werden. Die Reduzierung der Schweißgeschwindigkeit hat eine Verringerung der notwendigen Laserleistung zur Folge und begünstigt außerdem die mechanisch-technologischen Eigenschaften, infolge der reduzierten Abkühlgeschwindigkeit. Durch die geringe Martensitbildung führt dies zu einer Verbesserung der Kerbschlagzähigkeit. T2 - 19. Tagung in Hamburg - DVS CY - Hamburg, Germany DA - 24.04.2019 KW - Laser-Hybridschweißen KW - Elektromagnetische Schmelzbadunterstützung KW - Schweißen von kaltzähen Stählen PY - 2019 SP - 34 EP - 46 PB - DVS AN - OPUS4-47918 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Marquardt, R. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Laser-Pulver-Auftragschweißen von funktional gradierten Materialien auf Cobalt-Chrom Basis N2 - Um Bauteile vor Verschleiß und Korrosion zu schützen werden Beschichtungen aus resistenteren Materialien aufgetragen. Hierzu zählen unter anderen die Legierungen auf Cobalt-Chrom Basis. Der diskrete Materialsprung ist jedoch unter thermischen und mechanischen Belastungen häufig Ursache für das Versagen der Beschichtung. In dieser Arbeit werden daher Materialgradierungen von verschiedenen Stahllegierungen zu einer Cobalt-Chrom Basislegierung untersucht. Die Ergebnissen werden dafür auch mit Resultaten zu vorangegangenen Untersuchungen verglichen. Kern der Arbeit bilden geätzte Schliffbilder der Materialpaarungen und Auswertungen mittels Farbeindringprüfung sowie die metallografische Bestimmung der Porosität. Ziel der Arbeit ist ein defektfreier Aufbau der funktional gradierten Materialpaarungen. T2 - 43. Assistentenseminar Fügetechnik CY - Päwesin, Germany DA - 20.09.2023 KW - Directed Enery Deposition KW - Funktionally Graded Material KW - Additive Manufacturing KW - DED KW - FGM KW - AM PY - 2023 SN - 978-3-96144-212-6 SP - 1 EP - 6 PB - DVS Media GmbH AN - OPUS4-59116 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brunner-Schwer, C. A1 - Graf, B. A1 - Rethmeier, Michael T1 - Laser-Plasma-Hybrid-Cladding: Possibilities in the combination 2 of arc and laser for deposition welding N2 - Plasma-Transferred-Arc (PTA) welding is a process that enables high deposition rates, but also causes increased thermal load on the component. Laser based Direct Energy Deposition (DED) welding, on the other hand, achieves a high level of precision and thus comparatively low deposition rates, which can lead to high processing costs. Combining laser and arc energy aims to exploit the respective advantages of both technologies. In this study, different possibilities of this process combination are presented using a PTA system and a 2 kW disk laser. This includes the combination in a common process zone as a highspeed plasma laser cladding technology (HPLC), which achieves process speeds of 10 m/min. Besides that it is being examined whether a pre-running plasma arc can be used to coat difficult-to-weld rail steel with a carbon content of 0.8 % due to a preheating effect. Furthermore, a smoothing of the coating by a plasma arc following the laser is investigated. T2 - Lasers in Manufacturing 2019 CY - Munich, Germany DA - 24.06.2019 KW - Plasma-Transferred-Arc KW - Direct Energy Deposition KW - highspeed plasma laser cladding KW - deposition welding PY - 2019 SP - 1 EP - 9 AN - OPUS4-48724 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brunner-Schwer, C. A1 - Kersting, R. A1 - Graf, B. A1 - Rethmeier, Michael T1 - Laser-plasma-cladding as a hybrid metal deposition-technology applying a SLM-produced copper plasma nozzle N2 - Laser-Metal-Deposition (LMD) and Plasma-Transferred-Arc (PTA) are well known Technologies which can be used for cladding purposes. The prime objective in combining LMD and PTA as a Hybrid Metal Deposition-Technology (HMD) is to achieve high Deposition rates at low thermal Impact. Possible applications are coatings for wear protection or repair welding for components made of steel. The two energy sources (laser and Plasma arc) build a Joint process Zone and are configurated to constitute a stable process at laser powers between 0.4-1 kW (defocused) and Plasma currents between 75-200 A. Stainless steel 316L serves as filler material. For this HMD process, a Plasma Cu-nozzle is designed and produced by powder bed based Selective Laser Melting. The potential of the HMD Technology is investigated and discussed considering existing process. This paper demonstrates how the interaction of the two energy sources effects the following application-relevant properties: Deposition rate, powder Efficiency and energy Input. T2 - LANE 2018 CY - Fürth, Germany DA - 3.09.2018 KW - Laser-metal-deposition KW - Plasma-transferred-arc KW - SLM printed plasma torch KW - Laser-plasma hybrid PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-470999 UR - 10.1016/j.procir.2018.08.020 DO - https://doi.org/10.1016/j.procir.2018.08.020 SN - 2212-8271 VL - CIRP 74 SP - 738 EP - 742 PB - Sciencedirect CY - Berlin AN - OPUS4-47099 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael A1 - Gook, S. A1 - Gumenyuk, Andrey T1 - Laser-GMA-hybrid welding of longitudinally welded large-diameter pipes of grades API- X80/ X120 N2 - Potentials of the hybrid laser arc welding processes were investigated regarding reliable production of longitudinal welds of high strength pipe steels X80 and X120 Hybrid laser arc welding of the root pass: Significant reduction in the weld cross section – savings of filler material Lower heat input into the base material - improvement of mechanical properties of the weld joint  The arc type does not have any influence on the character of dilution in the laser part of the hybrid weld  14 mm deep root face was considered as optimum. No penetration of the filler material could be detected beyond this depth limit Metal powder filler wires, micro alloyed with Ni and partly with Cr and Mo, guaranteed sufficient Charpy impact toughness at low temperature for the both investigated materials: Hybrid laser arc welding is a very efficient process for the root pass in multi-pass welding and opens a large technical and economic potential for the manufacture of large pipes T2 - The METEC and 2nd European Steel Technology and Application Days (ESTAD)conference CY - Düsseldorf, Germany DA - 15.06.2015 KW - High power laser KW - Hybrid laser arc welding KW - Weld specimens KW - Charpy V-notch tests KW - Tensile tests PY - 2015 AN - OPUS4-38342 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jokisch, T. A1 - Marko, A. A1 - Gook, S. A1 - Üstündag, Ö. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Laser Welding of SLM-Manufactured Tubes Made of IN625 and IN718 N2 - The advantage of selective laser melting (SLM) is its high accuracy and geometrical flexibility. Because the maximum size of the components is limited by the process chamber, possibilities must be found to combine several parts manufactured by SLM. An application where this is necessary, is, for example, the components of gas turbines, such as burners or oil return pipes, and inserts, which can be joined by circumferential welds. However, only a few investigations to date have been carried out for the welding of components produced by SLM. The object of this paper is, therefore, to investigate the feasibility of laser beam welding for joining SLM tube connections made of nickel-based alloys. For this purpose, SLM-manufactured Inconel 625 and Inconel 718 tubes were welded with a Yb:YAG disk laser and subsequently examined for residual stresses and defects. The results showed that the welds had no significant influence on the residual stresses. A good weld quality could be achieved in the seam circumference. However, pores and pore nests were found in the final overlap area, which meant that no continuous good welding quality could be accomplished. Pore formation was presumably caused by capillary instabilities when the laser power was ramped out. KW - Inconel 718 KW - Laser welding KW - Selective Laser Melting KW - Laser Powder Bed Fusion PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-489679 DO - https://doi.org/10.3390/ma12182967 SN - 1996-1944 VL - 12 IS - 18 SP - 2967, 1 EP - 15 PB - Multidisciplinary Digital Publishing Institute CY - Basel AN - OPUS4-48967 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brunner-Schwer, C. A1 - Simón Muzás, Juan A1 - Biegler, M. A1 - Hilgenberg, Kai A1 - Rethmeier, Michael T1 - Laser Welding of L-PBF AM components out of Inconel 718 N2 - With regard to efficient production, it is desirable to combine the respective advantages of additively and conventionally manufactured components. Particularly in the case of large-volume components that also include filigree or complex structures, it makes sense to divide the overall part into individual elements, which afterwards have to be joined by welding. The following research represents a first step in fundamentally investigating and characterizing the joint welding of Laser Powder Bed Fusion (L-PBF) components made of Inconel 718. For this purpose, bead-on-plate welds were performed on plates manufactured using the L-PBF process and compared with the conventionally manufactured material. Conventional laser beam welding was used as welding process. The weld geometry was investigated as a function of the L-PBF build-up orientation. It was found that the welding depth and weld geometry differ depending on this orientation and in comparison to the conventional material. T2 - 12th CIRP Conference on Photonic Technologies [LANE 2022] CY - Fürth, Germany DA - 04.09.2022 KW - Laser Welding KW - L-PBF KW - PBF-LB/M KW - Seam geometry KW - Bead-on-plate welds PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-560012 DO - https://doi.org/10.1016/j.procir.2022.08.072 SN - 2212-8271 VL - 111 SP - 92 EP - 96 PB - Elsevier B.V. AN - OPUS4-56001 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Srinivasan, Krishnanand A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Laser Metal Deposition of Rene 80 – Microstructure and Solidification Behaviour Modelling N2 - New developments in nickel-based superalloys and production methods, such as the use of additive manufacturing (AM), can result in innovative designs for turbines. It is crucial to understand how the material behaves during the AM process to advance industrial use of these techniques. An analytical model based on reaction-diffusion formalism is developed to better explain the solidification behavior of the material during laser metal deposition (LMD). The well-known Scheil-Gulliver theory has some drawbacks, such as the assumption of equilibrium at the solid-liquid interface, which is addressed by this method. The solidified fractions under the Scheil model and the pure equilibrium model are calculated using CALPHAD simulations. Differential scanning calorimeter is used to measure the heat flow during the solid-liquid phase transformation, the result of which is further converted to solidified fractions. The analytical model is compared with all the other models for validation. T2 - Lasers in Manufacturing Conference 2023 CY - Munich, Germany DA - 26.06.2023 KW - Additive manufacturing KW - Laser metal deposition KW - Solidification behaviour KW - Analytical model KW - Nickel-based superalloy PY - 2023 SP - 1 EP - 10 AN - OPUS4-58612 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Petrat, T. A1 - Graf, B. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael ED - Schmidt, M. ED - Vollertsen, F. ED - Arnold, C. B. T1 - Laser metal deposition as repair technology for a gas turbine burner made of Inconel 718 N2 - Maintenance, repair and overhaul of components are of increasing interest for parts of high complexity and expensive manufacturing costs. In this paper a production process for laser metal deposition is presented, and used to repair a gas turbine burner of Inconel 718. Different parameters for defined track geometries were determined to attain a near net shape deposition with consistent build-up rate for changing wall thicknesses over the manufacturing process. Spot diameter, powder feed rate, welding velocity and laser power were changed as main parameters for a different track size. An optimal overlap rate for a constant layer height was used to calculate the best track size for a fitting layer width similar to the part dimension. Deviations in width and height over the whole build-up process were detected and customized build-up strategies for the 3D sequences were designed. The results show the possibility of a near net shape repair by using different track geometries with laser metal deposition. T2 - LANE - 9 International Conference on Photonic Technologies CY - Fürth, Germany DA - 19.09.2016 KW - Laser metal deposition KW - Inconel 718 KW - Additive manufacturing KW - Maintenance KW - Repair and overhaul PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-376723 UR - http://ac.els-cdn.com/S1875389216301857/1-s2.0-S1875389216301857-main.pdf?_tid=ed1d75de-84a2-11e6-af94-00000aab0f6c&acdnat=1474974777_4917d753cb3d316c4b000ba0760778b5 DO - https://doi.org/10.1016/j.phpro.2016.08.078 SN - 1875-3892 VL - 83 SP - 761 EP - 768 PB - Elservier AN - OPUS4-37672 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jokisch, T. A1 - Gook, S. A1 - Marko, A. A1 - Üstündag, Ömer A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Laser beam welding of additive manufactured components: Applicability of existing valuation regulations N2 - With additive manufacturing in the powder bed, the component size is limited by the installation space. Joint welding of additively manufactured parts offers a possibility to remove this size limitation. However, due to the specific stress and microstructure state in the additively built material, it is unclear to what extent existing evaluation rules of joint welding are also suitable for welds on additive components. This is investigated using laser beam welding of additively manufactured pipe joints. The welds are evaluated by means of visual inspection, metallographic examinations as well as computed tomography. The types of defects found are comparable to conventional components. This is an indicator that existing evaluation regulations also map the possible defects occurring for weld seams on additive components. KW - Weld imperfections KW - Additive manufacturing KW - Weldability KW - Laser welding PY - 2022 VL - 2 SP - 109 EP - 113 PB - DVS Media GmbH AN - OPUS4-56374 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, A. A1 - Goecke, S.F. A1 - Rethmeier, Michael T1 - Laser beam oscillation welding for automotive applications N2 - Laser beam oscillation, applied one- or two-dimensional to the actual welding process, influences the welding process in terms of compensation of tolerances and reduction of process emissions like spatter and melt ejections that occur in industrial applications, such as in body-in-white manufacturing. If the welding process could be adapted to these tolerances by the momentarily demanded melt pool width to generate sufficient melt volume or to influence melt pool dynamics, e.g. for a better degassing, laser welding would become more robust. However, beam oscillation results are highly dependent on the natural frequency of the melt pool, the used spot diameter and the oscillation speed of the laser beam. The conducted investigations with an oscillated 300 μm laser spot show that oscillation strategies which are adjusted to the joining situation can bridge gaps to approximately 0.6 mm at metal sheet thickness of 0.8 mm. However, the complex behaviour of the melt pool has to be considered to generate proper welding results. This work puts emphasis on showing aspects of beam oscillation in fillet welding in lap joints. KW - Automotive application KW - Melt pool dynamics KW - Adaptive welding beam oscillation KW - Laser welding KW - Gap bridging PY - 2018 DO - https://doi.org/10.1007/s40194-018-0625-3 SN - 0043-2288 SN - 1878-6669 VL - 62 IS - 5 SP - 1039 EP - 1047 PB - Springer AN - OPUS4-45774 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jonietz, Florian A1 - Myrach, Philipp A1 - Rethmeier, Michael A1 - Suwala, H. A1 - Ziegler, Mathias T1 - Laser Based Spot Weld Characterization N2 - Spot welding is one of the most important joining technologies, especially in the automotive industry. Hitherto,the quality of spot welded joints is tested mainly by random destructive tests. A nondestructive testing technique offers the benefit of cost reduction of the testing procedure and optimization of the fabrication process, because every joint could be examined. This would lead to a reduced number of spot welded joints, as redundancies could be avoided. In the procedure described here, the spot welded joint between two zinc-coated steel sheets (HX340LAD+Z100MB or HC340LA+ZE 50/50) is heated optically on one side. Laser radiation and flash light are used as heat sources. The melted zone, the so called “weld nugget” provides the mechanical stability of the connection, but also constitutes a thermal bridge between the sheets. Due to the better thermal contact, the spot welded joint reveals a thermal behavior different from the surrounding material, where the heat transfer between the two sheets is much lower. The difference in the transient thermal behavior is measured with time resolved thermography. Hence, the size of the thermal contact between the two sheets is determined, which is directly correlated to the size of the weld nugget, indicating the quality of the spot weld. The method performs well in transmission with laser radiation and flash light. With laser radiation, it works even in reflection geometry, thus offering the possibility of testing with just one-sided accessibility. By using heating with collimated laser radiation, not only contactfree, but also remote testing is feasible. A further convenience compared to similar thermographic approaches is the applicability on bare steel sheets without any optical coating for emissivity correction. For this purpose, a proper way of emissivity correction was established. T2 - 42ND ANNUAL REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION: Incorporating the 6th European-American Workshop on Reliability of NDE CY - Minneapolis, Minnesota, USA DA - 26.07.2015 KW - Laser PY - 2016 SN - 978-0-7354-1353-5 DO - https://doi.org/10.1063/1.4940570 VL - 1706 SP - 100010-1 EP - 100010-8 PB - AIP Publishing AN - OPUS4-35367 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gook, S. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael A1 - El-Batahgy, A.M. T1 - Laser and hybrid laser-arc welding of cryogenic 9 % NI Steel N2 - Heat treated 9%Ni steel is considered the most suitable and economic material for construction of large-size liquefied natural gas (LNG) storage tanks which operate at cryogenic temperatures (-196°C). Strength above 700 MPa as well as a minimum impact value of 60 J are required to ensure reliable operation of the LNG tanks at operating temperature. Conventional arc welding processes, including shielded metal arc welding, gas metal arc welding, gas tungsten arc welding and submerged arc welding, are currently used in construction of LNG tanks. Ni based filler wire is the preferred filler metal of choice in LNG tank construction. The main problem with this choice is the lower mechanical properties, particularly tensile strength of the weld metal. To compensate, the wall thickness needs to be excessively thick to ensure the strength of the welded structures. Ni based filler material is expensive and a large quantity is needed to fill the multi-pass weld grooves. These factors significantly add to the cost in the fabrication of LNG storage tanks. For these reasons, exploration of new welding technologies is a priority. A big potential can be seen in laser based welding techniques. Laser beam welding results in much smaller fusion zone with chemical composition and mechanical properties similar to that of the base material. Laser welding is a much faster process and allows for a joint geometry which requires less filler material and fewer welding passes. The advantages of laser welding can help to overcome the problems pointed out above. Trials of autogenous laser welding, laser cold-wire welding and hybrid laser-arc welding conducted on the 9%Ni steel are presented in this paper. Chemical composition of the weld metal as well as effects of welding parameters on the weld formation, microstructure and tensile strength is discussed. Filler wire penetration depth as well as character of its distribution in the narrow laser welds was examined using EPMA - electron probe microanalysis. KW - hardness KW - cryogenic steel KW - laser welding KW - microstructure KW - tensile strength PY - 2016 UR - http://gns.mephi.ru/sites/default/files/journal/file/en.2016.1-4.pdf SN - 2499-9733 VL - 1 IS - 18 SP - 34 EP - 45 PB - Research Nuclear University MEPHl CY - Moskau, Russia AN - OPUS4-36553 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Artinov, Antoni A1 - Karkhin, V. A1 - Bakir, Nasim A1 - Meng, Xiangmeng A1 - Bachmann, Marcel A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Lamé curves approximation for the assessment of the 3-D temperature distribution in keyhole mode welding processes N2 - A novel approach for the reconstruction of an equivalent volumetric heat source from a known weld pool shape is proposed. It is based on previously obtained weld pool geometries from a steady-state thermo-fluid dynamics simulation. Hereby the weld pool dimensions are obtained under consideration of the most crucial physical phenomena, such as phase transformations, thermo-capillary convection, natural convection and temperature-dependent material properties. The algorithm provides a time and calibration efficient way for the reproduction of the weld pool shape by local Lamé curves. By adjusting their parameters, the identification of the finite elements located within the weld pool is enabled. The heat input due to the equivalent heat source is assured by replacing the detected nodes’ temperature by the melting temperature. The model offers variable parameters making it flexible and adaptable for a wide range of workpiece thicknesses and materials and allows for the investigation of transient thermal effects, e.g. the cooling stage of the workpiece. The calculation times remain acceptably short especially when compared to a fully coupled process simulation. The computational results are in good agreement with performed complete-penetration laser beam welding experiments. T2 - ICALEO 2019 - 38th International congress on applications of lasers & electro-optics CY - Orlando, FL, USA DA - 07.10.2019 KW - Weld pool shape approximation KW - Keyhole mode laser beam welding KW - Numerical simulation KW - Superelliptic Lamé curves PY - 2019 UR - http://icaleo.conferencespot.org/2019-proceedings?qr=1 SN - 978-1-940168-1-42 SP - Paper # Macro 1002 AN - OPUS4-49310 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Artinov, Antoni A1 - Karkhin, V. A1 - Bakir, Nasim A1 - Meng, Xiangmeng A1 - Bachmann, Marcel A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Lamé curve approximation for the assessment of the 3D temperature distribution in keyhole mode welding processes N2 - A novel approach for the reconstruction of an equivalent volumetric heat source from a known weld pool shape is proposed. It is based on previously obtained weld pool geometries from a steady-state thermo-fluid dynamics simulation. Hereby, the weld pool dimensions are obtained under consideration of the most crucial physical phenomena, such as phase transformations, thermo-capillary convection, natural convection, and temperature-dependent material properties. The algorithm provides a time and calibration efficient way for the reproduction of the weld pool shape by local Lamé curves. By adjusting their parameters, the identification of the finite elements located within the weld pool is enabled. The heat input due to the equivalent heat source is assured by replacing the detected nodes’ temperature by the melting temperature. The model offers variable parameters making it flexible and adaptable for a wide range of workpiece thicknesses and materials and allows for the investigation of transient thermal effects, e.g., the cooling stage of the workpiece. The calculation times remain acceptably short especially when compared to a fully coupled process simulation. The computational results are in good agreement with performed complete-penetration laser beam welding experiments. KW - Lamé curves approximation KW - Equivalent heat source KW - Thermal cycles KW - Numerical modeling KW - Keyhole mode welding PY - 2020 DO - https://doi.org/10.2351/7.0000076 VL - 32 IS - 2 SP - 022042-1 EP - 022042-8 PB - AIP Publishing AN - OPUS4-50768 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Marquardt, R. A1 - Bähring, S. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Künstliche Neuronale Netze zur Qualitätsprognose von Funktional Gradierten Materialien im laserbasierten Directed Energy Deposition N2 - Durch pulverbasiertes Directed-Energy Deposition lassen sich Gradierungen fertigen, um diskrete Materialübergänge zu vermeiden und die Lebensdauer von Hartschichten zu erhöhen. Die Kombination aus Stahl als Basiswerkstoff und einer verschleiß- und korrosionsbeständigen Co-Cr Legierung verspricht durch Vermeiden von Spannungskonzentrationen das Verhindern von Abplatzungen und Rissen in der Schutzschicht. Um die Qualität des gefertigten Bauteils zu beurteilen, liegen für solche Funktional Gradierten Materialien (FGM) wenig Erkenntnisse vor. Daher wird im Rahmen dieser Studie eine Methodik erarbeitet, um die relative Dichte eines Funktional Gradierten Materials auf Stahl und Co-Cr Basis mittels Maschinendaten zu bestimmen. Anschließend wird unter Einsatz eines künstlichen neuronalen Netzes anhand von Sensordaten die relative Dichte vorhergesagt. Das trainierte Netz erreicht eine Vorhersagegenauigkeiten von 99,83%. Abschließend wird eine Anwendung anhand von einem Demonstrator gezeigt. T2 - 3. Fachtagung Additive Manufacturing CY - Halle, Germany DA - 05.10.2023 KW - Directed Enery Deposition KW - Künstliche Neuronale Netze KW - Additive Manufacturing KW - DED KW - KI KW - AM PY - 2023 SP - 1 EP - 8 PB - SLV Halle AN - OPUS4-58692 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - El-Sari, B. A1 - Biegler, M. A1 - Gook, S. A1 - Rethmeier, Michael T1 - KI zur Prozessüberwachung im Unterpulverschweißen N2 - Beim Unterpulverschweißen sind die Prozessgeräusche ein Indikator für eine gute Fügequalität. Diese Beurteilung kann i.d.R. nur von einer erfahrenen Fachkraft durchgeführt werden. Eine kürzlich entwickelte künstliche Intelligenz kann automatisch das akustische Prozesssignal anhand vortrainierter Merkmale klassifizieren und die Fügequalität anhand des Geräuschs beurteilen. Der Algorithmus, einmal richtig trainiert, kann den Prüfaufwand beim Unterpulverschweißen deutlich reduzieren. KW - Unterpulverschweißen KW - Künstliche Intelligenz KW - Prozessüberwachung KW - Körperschall PY - 2024 SP - 1 EP - 2 AN - OPUS4-59483 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Kantenbeschichtung für das Laserstrahlschweißen dickwandiger Duplexstahl-Bleche N2 - Duplexstähle finden in vielen industriellen Bereichen Anwendung, dies ist nicht zuletzt ihren hervorragenden Eigenschaften, wie einer guten Korrosionsbeständigkeit, einer guten Duktilität bei trotzdem hoher Festigkeit, zuzuschreiben. Diese Eigenschaften werden jedoch durch das Schweißen, vor allem das Laserstrahlschweißen, beeinträchtigt, da die hohen Abkühlraten zu erhöhten Ferritanteilen im Schweißgut führen. Mit Hilfe eines zweistufigen Prozesses, bei dem die Kanten der Fügepartner vor dem Schweißen mit nickelhaltigem Pulver beschichtet werden, soll dieses Problem für dickwandige Bleche gelöst werden. In diesem Zusammenhang wurden verschiedene Prozessparameter für den Laser-Pulver-Auftragschweiß-Prozess untersucht sowie die defektfreie Schweißung dieser beschichteten Kanten mit unterschiedlichen Prozessgasen. KW - Pufferschichten KW - Laser-Pulver-Auftragschweißen KW - Laserstrahlschweißen KW - Duplex PY - 2020 VL - 72 IS - 7 SP - 382 EP - 387 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-50145 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gook, S. A1 - Midik, A. A1 - Biegler, M. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Joining 30 mm Thick Shipbuilding Steel Plates EH36 Using a Process Combination of Hybrid Laser Arc Welding and Submerged Arc Welding N2 - This article presents a cost-effective and reliable method for welding 30 mm thick sheets of shipbuilding steel EH36. The method proposes to perform butt welding in a two-run technique using hybrid laser arc welding (HLAW) and submerged arc welding (SAW). The HLAW is performed as a partial penetration weld with a penetration depth of approximately 25 mm. The SAWis carried out as a second run on the opposite side. With a SAWpenetration depth of 8 mm, the weld cross-section is closed with the reliable intersection of both passes. The advantages of the proposed welding method are: no need for forming of the HLAW root; the SAW pass can effectively eliminate pores in the HLAWroot; the high stability of the welding process regarding the preparation quality of the weld edges. Plasma cut edges can be welded without lack of fusion defects. The weld quality achieved is confirmed by destructive tests. KW - Shipbuilding steel KW - Hybrid laser arc welding KW - Submerged arc welding KW - Hardness KW - Bending test KW - Two-run welding technique KW - Microstructure PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-556090 DO - https://doi.org/10.3390/jmmp6040084 SN - 2504-4494 VL - 6 IS - 4 SP - 1 EP - 11 PB - MDPI CY - Basel AN - OPUS4-55609 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brunner-Schwer, Chr. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Investigation on laser cladding of rail steel without preheating N2 - 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 heavy haul applications. 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, the utilized steel grades lead to martensite formation and cracking during deposition welding. In this study, laser cladding of low-alloy steel at very high speeds was 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. Within the resulting narrow HAZ, the hardness could be significantly reduced. T2 - Lasers in Manufacturing Conference 2021 CY - Erlangen, Germany DA - 21.06.2021 KW - High speed laser cladding KW - Preheatin KW - Rail tracks KW - Pearlitic microstructure PY - 2021 AN - OPUS4-53974 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Üstündag, Ö. A1 - Gook, S. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Investigation of the mechanical properties of single-pass hybrid laser-arc welded thick X120 pipeline steel plates N2 - With global increases in clean energy demand, the natural gas is gaining in importance. Pipelines are the safest and most cost-effective way of transporting natural gas. Due to high transport volume and resulting high operation pressure, the demand for ultra-high strength steel grades such as X120 is very strong. As a result of the fact that these steels are produced by thermo-mechanical controlled processing, the welding process must be selected accordingly. Based on investigations, a high heat input such as by submerged arc welding process leads to softening in the weld metal and loss of strength whereas pure laser beam welding results in high cooling rates and deteriorate toughness of the weld metal. The objective of this research is to investigate the influence of heat input to mechanical properties of hybrid laser-arc welded pipeline steels of grade X120. Test specimens with a thickness of 20 mm could be welded without preheating in a single-pass with different welding velocities to observe the largest possible parameter window of the heat input. The achieved V-notch impact energy for hybrid laser-arc welded samples was 144±37 J at a testing temperature of -40 °C. With a tensile strength of 930±4 MPa the requirements of API 5L was achieved. To prevent gravity drop-outs at the slow welding speeds, an electromagnetic weld pool support system was used, which works contactless and is based on generating Lorentz forces. It was therefore possible to control the cooling rate in order to meet the requirements of the mechanical properties. By adapting the electromagnetic weld pool support to the laser and laser hybrid welding process, the application potential of these technologies for industrial implementation can be drastically increased. T2 - 14th Pipeline Technology Conference CY - Berlin, Germany DA - 18.03.2019 KW - Mechanical properties KW - Hybrid laser arc welding KW - Pipeline steel X120 PY - 2019 UR - https://www.pipeline-conference.com/conferences/14th-pipeline-technology-conference-2019 SN - 2510-6716 SP - 1 EP - 10 AN - OPUS4-48970 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - El-Sari, B. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Investigation of the LME Susceptibility of Dual Phase Steel with Different Zinc Coatings N2 - The application of anti-corrosion coated, high-strength steels in the automotive industry has increased in recent years. In combination with various zinc-based surface coatings, liquid metal embrittlement cracking can be observed in some of these materials. A high-quality, crack-free spot-welded joint is essential to realize the lightweight potential of the materials. In this work, the LME susceptibility of different coatings, which will be determined by the crack length and the occurrence rate, will be investigated using a welding under external load setup. The uncoated specimens did not show any LME. EG, GI and GA showed significantly less LME than ZM coatings. The latter coatings showed much larger crack lengths than the EG, GI and GA coatings. Furthermore, two mechanisms regarding the LME occurrence rate were observed: the occurrence of LME in zinc–magnesium coatings was theorized to be driven by the material properties of the coatings, whereas the occurrence of LME at EG, GI and GA samples was forced mainly by the application of the external tensile load. In the experimental setup of this work, the materials were exposed to unusually high mechanical loads (up to 80% of their yield strength) to evoke LME cracks. KW - Widerstandspunktschweißen KW - Hochfester Stahl KW - Liquid Metal Embrittlement KW - Flüssigmetallinduzierte Rissbildung KW - Zink KW - AHSS PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-580428 DO - https://doi.org/10.3390/met13050890 VL - 13 IS - 5 SP - 1 EP - 11 PB - MDPI AN - OPUS4-58042 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael A1 - Üstündag, Ömer A1 - Bakir, Nasim A1 - Gumenyuk, Andrey T1 - Investigation of the gap bridgeability at high-power laser hybrid welding of plasma-cut thick mild steels with AC magnetic support N2 - One of the challenges of the high-power hybrid laser welding of thick steels is the sensitivity of the process of the process to manufacturing tolerances. This usually leads to a time-consuming preparation of the welding edges, such as milling. The study deals with the influence of the edge quality of milled and plasma-cut steel made of S355J2 with a wall thickness of 20 mm on the laser hybrid welded seam quality. Furthermore, the gap bridgeability and the tolerances towards edge misalignment was investigated. An AC magnet was used as backing support to prevent sagging and positioned under the workpiece, to generate an upwards directed electromagnetic pressure. The profiles of the edges and the gap on the top and root side were measured using a digital camera. Single-pass laser hybrid welds of plasma-cut edges could be welded using a laser beam power of just 13.7 kW. A gap bridgeability up to 2 mm and misalignment of edges up to 2 mm could be achieved successful. Additionally, the independence of the cutting side and the welding side was shown, so that samples were welded to the opposite side to their cutting. For evaluation of internal defects or irregularities, X-ray images were carried out. Charpy impact strength tests were performed to determine the toughness of the welds. T2 - X International Conference «Beam Technologies & Laser Application CY - Online meeting DA - 20.09.2021 KW - Plasma-cutting KW - Hybrid laser-arc welding KW - Thick-walled steel KW - Edge quality KW - Gap bridgeability KW - Misalignment of the edges PY - 2021 AN - OPUS4-53920 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Üstündag, Ömer A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Investigation of the gap bridgeability at high-power laser hybrid welding of plasma-cut thick mild steels with AC magnetic support N2 - One of the challenges of the high-power hybrid laser welding of thick steels is the sensitivity of the process of the process to manufacturing tolerances. This usually leads to a time-consuming preparation of the welding edges, such as milling. The study deals with the influence of the edge quality of milled and plasma-cut steel made of S355J2 with a wall thickness of 20 mm on the laser hybrid welded seam quality. Furthermore, the gap bridgeability and the tolerances towards edge misalignment was investigated. An AC magnet was used as backing support to prevent sagging and positioned under the workpiece, to generate an upwards directed electromagnetic pressure. The profiles of the edges and the gap on the top and root side were measured using a digital camera. Single-pass laser hybrid welds of plasma-cut edges could be welded using a laser beam power of just 13.7 kW. A gap bridgeability up to 2 mm and misalignment of edges up to 2 mm could be achieved successful. Additionally, the independence of the cutting side and the welding side was shown, so that samples were welded to the opposite side to their cutting. For evaluation of internal defects or irregularities, X-ray images were carried out. Charpy impact strength tests were performed to determine the toughness of the welds. T2 - X International Conference «Beam Technologies & Laser Application» KW - Laser hybrid welding KW - Magnetic bath support KW - Plasma-cut samples KW - Thick plate welding PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-539248 DO - https://doi.org/10.1088/1742-6596/2077/1/012007 VL - 2077 IS - 012007 SP - 1 EP - 8 PB - IOP Publishing AN - OPUS4-53924 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - El-Sari, B. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Investigation of the Application of a C-ring Geometry to validate the Stress Relief Heat Treatment Simulation of Additive Manufactured Austenitic Stainless Steel Parts via Displacement N2 - Directed energy deposition is a metal additive manufacturing process that builds parts by joining material in a layer-by-layer fashion on a substrate. Those parts are exposed to rapid thermo-cycles which cause steep stress gradients and the layer-upon-layer manufacturing fosters an anisotropic microstructure, therefore stress relief heat treatment is necessary. The numerical simulation can be used to find suitable parameters for the heat treatment and to reduce the necessary efforts to perform an effective stress relieving. Suitable validation Experiments are necessary to verify the results of the numerical simulation. In this paper, a 3D coupled thermo-mechanical model is used to simulate the heat treatment of an additive manufactured component to investigate the application of a C-ring geometry for the distortion-based validation of the numerical simulation. Therefore, the C-ring samples were 3D scanned using a structured light 3D scanner to quantify the distortion after each process step. KW - Additive manufacturing KW - Directed energy deposition KW - Laser KW - Heat treatment KW - Numerical simulation PY - 2020 DO - https://doi.org/10.3139/105.110417 VL - 75 IS - 4 SP - 248 EP - 259 PB - Carl Hanser Verlag AN - OPUS4-51318 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pavlov, V. A1 - Gumenyuk, Andrey A1 - Volvenko, S. A1 - Rethmeier, Michael A1 - Bakir, Nasim T1 - Investigation of solidification cracking susceptibility of type 316L stainless steel during laser beam welding using an in-situ observation technique N2 - Laser welding is a widely established manufacturing process in many industry sectors. Solidification cracking as well as the weldability of materials is still since many years a highly contentious issue, particularly regarding the causes of the hot crack formation. Many of studies have been conducted to determine the critical conditions of occurrence of the solidification cracking. In this study a 2D in-situ observation technique in conjunction with laser diodes as the illuminating source has been employed to measure the arising strain field during the laser beam welding process. For the first time the employed technique enabled the in-situ measurement of the transient strain field at the surface of the workpiece directed to the laser beam in the critical range, where the solidification cracking normally occurs. Thus the critical threshold strain values at high temperatures characterizing transition from crack free to crack concomitant welding process could be deduced. T2 - Lasers in Manufacturing Conference 2017 CY - Munich, Germany DA - 26.06.2017 KW - Laser beam Welding KW - Optical measurement technique KW - Critical strain KW - Solidification cracking PY - 2017 SP - 1 EP - 7 AN - OPUS4-41175 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Investigation of solidification cracking susceptibility of laser welded joints of austenitic stainless steels N2 - Laser welding is a widely established manufacturing process in many industry sectors. Solidification cracking represents one of the most inadequately solved problems in welding and has major economic implications. The avoidance of hot crack forms for most fusion welding processes poses a key challenge for an important range of metallic construction materials and affects not only the manufacturers of welding equipment and material manufacturers, but also a large number of customers using welding technologies, as well as welding technical standardization and research. Solidification cracking susceptibility was examined with the help of the Controlled Tensile Weldability Test (CTW) developed by Federal Institute for Materials Research and Testing (BAM), Berlin. The test is based on the fact that hot crack formation depends on a critical strain that emerges within a critical temperature range, the so called brittle temperature range (BTR). Using this test and defined investigation programme a centreline solidification crack was generated. By controlling the applied strain during the laser beam welding process, it was possible to determine the critical strain and strain rate that led to solidification cracking formation. The hot cracking susceptibility of the tested stainless steels was qualified and quantified. The results demonstrate that the crack length increases with increasing applied strain. Furthermore, the strain rate has a significant influence on the formation of the solidification crack. T2 - 3rd International conference in Africa and Asia CY - Luxor, Egypt DA - 02.11.2015 KW - Laser beam welding KW - Hot cracking KW - Solidification cracking KW - Hot cracking test PY - 2015 SP - A-29, 1 EP - A-29, 9 AN - OPUS4-36522 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Investigation of solidification cracking susceptibility during laser beam welding using an in-situ observation technique N2 - In recent years, laser beam welding has found wide applications in many industrial fields. Solidification cracks are one of the most frequently encountered welding defects that hinder obtaining a safe weld joint. Decades of research have shown that one of the main causes of such cracks are the strain and the strain rate. Obtaining meaningful measurements of these strains has always been a major challenge for scientists, because of the specific environment of the measurement range and the many obstacles, as well as the high temperature and the plasma plume. In this study, a special experimental setup with a high-speed camera was employed to measure the strain during the welding process. The hot cracking susceptibility was investigated for 1.4301 stainless steel, and the critical strain required for solidification crack formation was locally and globally determined. KW - Solidification cracking KW - Laser welding KW - Optical measurement KW - In situ strain KW - Critical strain KW - Strain rate PY - 2018 DO - https://doi.org/10.1080/13621718.2017.1367550 SN - 1362-1718 SN - 1743-2936 VL - 23 IS - 3 SP - 234 EP - 240 PB - Taylor and Francis AN - OPUS4-43992 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Investigation of solidification cracking susceptibility during laser beam welding using an in-situ observation technique N2 - Using the novel optical measurement technique together with the optical flow algorithm, a twodimensional deformation analysis during welding has been conducted. This technique provides for the first time a measurement of the strain field locally in the immediate vicinity of the assumed solidification front. The described procedure of the opticalmeasurement allows to determine the real martial-dependent values of critical strain and strain rate characterising transition to the hot cracking during laser welding processes. The local critical strain that obtained in the assumed solidification showed that the local critical strain decreases as the strain rate increases. Moreover, this phenomenon has also been shown with results from the CTW-test, since the global strain decreases with an increase in the external strain rate. KW - Novel optical measurement KW - Local critical strain KW - Solidification cracking KW - Laser beam Welding PY - 2017 DO - https://doi.org/10.1080/13621718.2017.1367550 SN - 1362-1718 SP - 1 EP - 7 PB - Taylor & Francis AN - OPUS4-42918 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Frei, J. A1 - Biegler, M. A1 - Rethmeier, Michael A1 - Böhne, Ch. A1 - Meschut, G. T1 - Investigation of liquid metal embrittlement of dual phase steel joints by electro-thermomechanical spot-welding simulation N2 - A 3D electro-thermomechanical model is established in order to investigate liquid metal embrittlement. After calibration to a dual phase steel of the 1000 MPa tensile strength class, it is used to analyse the thermo-mechanical system of an experimental procedure to enforce liquid metal embrittlement during resistance spot welding. In this procedure, a tensile stress level is applied to zinc coated advanced high strength steel samples during welding. Thereby, liquid metal embrittlement formation is enforced, depending on the applied stress level and the selected material. The model is suitable to determine and visualise the corresponding underlying stresses and strains responsible for the occurrence of liquid metal embrittlement. Simulated local stresses and strains show good conformity with experimentally observed surface crack locations. KW - RSW KW - LME KW - Advanced high strength steel KW - Zinc coated steel KW - Testing method KW - Dual phase steel KW - Cracking KW - Electro-thermomechnical model PY - 2019 DO - https://doi.org/10.1080/13621718.2019.1582203 SN - 1362-1718 SN - 1743-2936 VL - 24 IS - 7 SP - 624 EP - 633 PB - Taylor & Francis AN - OPUS4-47747 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Investigation of hot crack susceptibility of laser welded joints of four austenitic steels N2 - Laser welding is a widely established manufacturing process in many industry sectors. Solidification cracking represents one of the most inadequately solved problems in welding and has major economic implications. The avoidance of hot crack is for most fusion welding processes a key challenge for an important range of metallic construction materials and affects not only the manufacturers of welding equipment and material manufacturers, but also a large number of customers using welding technologies, as well as welding standardization and research. In this study a new investigation programme has been developed to qualify the hot cracking susceptibility of a variety of austenitic stainless steels. The results show the possibility of using this technique to determinate the critical values that occur with initiation of solidification cracking during laser beam welding T2 - The METEC and 2nd European Steel Technology and Application Days CY - Düsseldorf, Germany DA - 15.06.2015 KW - Laser beam welding KW - Hot cracking KW - Solidification cracking KW - Hot cracking test PY - 2015 SP - 1 EP - 5 AN - OPUS4-36525 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bachmann, Marcel A1 - Meng, Xiangmeng A1 - Artinov, Antoni A1 - Rethmeier, Michael T1 - Investigating defects caused by narrow pool shapes in deep penetration welding N2 - Laser beam welding is a widely used joining technique in many industrial applications. This is mainly due to its many unique advantages, especially compared to conventional arc welding processes. These advantages include, among others, highly concentrated energy deposition, low total heat input and a capacity to penetrate deep into the material while causing only small welding distortions. However, at the same time, the small dimension of the laser spot, high solidification rates, and small dimensions of the weld pool itself can provoke issues regarding the assembly tolerances of the workpiece, the hot-cracking phenomena, as well as keyhole-induced bubbles escaping from the melt. Weld pool shapes in laser beam welding are elongated at the external, free surfaces under the action of the main driving forces in the melt – such as recoil pressure and surface tension forces – while being shorter in the internal areas of the weld pool. This leads to a regular solidification sequence from the internal zones toward the free surfaces, e.g. from the bottom to the top in partial penetration welding. However, in recent studies reported in the literature and seen in the experimental and numerical investigations of BAM Bundesanstalt für Materialforschung und -prüfung in Berlin, it was found that an internal narrowing phenomenon can occur that is often accompanied by a distinct bulging of the weld bead in deeper zones. As the internal behaviour of the melt during the process is hardly optically accessible, several numerical models and experimental techniques were established to visualise the mechanisms of the formation of the bulging and the narrowing phenomenon and to reveal the consequences on the solidification sequence, pore formation, and filler metal dilution. KW - Weld pool shape KW - Laser beam welding KW - Solidification PY - 2022 SN - 1759-0752 IS - 57 SP - 28 EP - 29 PB - Europa Science CY - Cambridge, UK AN - OPUS4-56995 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Geisen, O. A1 - Müller, V. A1 - Graf, B. A1 - Rethmeier, Michael T1 - Integrated weld preparation designs for the joining of L‑PBF and conventional components via TIG welding N2 - size limitations and high production costs of L-PBF make it competitive for smaller, highly complex components, while the less complex elements of an assembly are manufactured conventionally. This leads to scenarios that use L-PBF only where it’s beneficial, and it require an integration and joining to form the final product. For example, L-PBF combustion swirlers are welded onto cast parts to produce combustion systems for stationary gas turbines. Today, the welding process requires complex welding fixtures and tack welds to ensure the correct alignment and positioning of the parts for repeatable weld results. In this paper, L-PBF and milled weld preparations are presented as a way to simplify the Tungsten inert gas (TIG) welding of rotationally symmetrical geometries using integrated features for alignment and fixation. Pipe specimens with the proposed designs are manufactured in Inconel 625 using L-PBF and milling. The pipe assembly is tested and TIG welding is performed for validation. 3D scans of the pipes before and after welding are evaluated, and the weld quality is examined via metallography and computed tomography (CT) scans. All welds produced in this study passed the highest evaluation group B according to DIN 5817. Thanks to good component alignment, safe handling, and a stable welding process, the developed designs eliminate the need for part-specific fixtures, simplify the process chain, and increase the process reliability. The results are applicable to a wide range of components with similar requirements. KW - L-PBF KW - AM feature integration KW - TIG welding KW - Integrated alignment features KW - Pipe weld preparation KW - Dissimilar joints KW - Inconel 625 PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-547042 DO - https://doi.org/10.1007/s40964-021-00221-2 SN - 2363-9512 SP - 1 EP - 11 PB - Springer AN - OPUS4-54704 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Javaheri, E. A1 - Pittner, Andreas A1 - Graf, B. A1 - Rethmeier, Michael T1 - Instrumented indentation technique and its application for the determination of local material properties of welded steel structures N2 - The determination of mechanical properties of welded Steel structures such as strength or ductility is a subject of high interest for the majority of Companies in the area of metal Processing. The material Parameters can be obtained by performing the tensile test on the samples made from a part of a component. In some cases, it is highly expensive to produce the tensile specimens especially from the weld metal, which contains different type of microstructure such as weld seam or heat affected zone in an extremely small area. Therefore, a method is described in this paper to determine the material Parameters of high strength Steel structures and welded joints locally and without any additional effort to perform the tensile test. In this method, instrumented indentation technique (IIT), an indenter is pushed on the flat surface of a specimen in a certain period of time and simultaneously the applied force and the corresponding indentation path are measured. The data related to the force-indentation diagram is given as input to an artificial neural network (ANN) to obtain the material Parameters. The ANN can be trained by generating the large qualitative data sets with numerical Simulation of the IIT procedure. The Simulation must be run several times with the different material model parameter sets to generate the numerous force-indentation diagrams as the inputs of ANN. Then, the trained ANN is validated by performing the IIT on the welded joints and comparing the obtained material Parameters from ANN with the tensile test. Consequently, the mechanical properties of welded joints can be determined by performing the IIT and evaluating the resulting data by the ANN. T2 - 39. Assistentenseminar CY - Eupen, Germany DA - 12.09.2018 KW - Steel PY - 2019 SN - 978-396144-070-2 SP - 146 EP - 152 PB - DVS Media GmbH AN - OPUS4-51317 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Winterkorn, René A1 - Fabry, Çağtay A1 - Rethmeier, Michael A1 - Ratkovac, Mirjana A1 - Thiele, Marc A1 - Baeßler, Matthias T1 - Innovative Design- und Fertigungsstrategien zur Steigerung der Leichtbaupotenziale im Stahlbau N2 - Ziel des Verbundvorhabens „SmartWeld“ ist es, für die schweißtechnische Fertigung von Stahlbaustrukturen exemplarisch am Beispiel von Hohlprofilknoten, welche als designrelevante Elemente von Gründungsstrukturen für Offshore-Windenergieanlagen (OWEA) einsetzbar sind, die Möglichkeiten des Leichtbaus unter konsequenter Digitalisierung der Fertigungskette aufzuzeigen, um einerseits die Ressourceneffizienz zu forcieren und gleichzeitig wettbewerbsfähige Fertigungsstrategien aufzuzeigen. Innerhalb von „SmartWeld“ werden daher die Möglichkeiten einer wirtschaftlichen Fertigung von Leichtbau-Gründungsstrukturen am Beispiel aufgelöster Tragstrukturen (Jackets) aufgezeigt. Eine lastgerechte Auslegung der Schweißverbindungen nach bionischen Prinzipien ermöglicht, weitere Einsparpotenziale an Ressourcen bei gleichzeitiger Erhöhung der Lebensdauer zu erschließen. Die Ausnutzung konstruktiver Prinzipien des Leichtbaus zur Erzeugung innovativer und ressourcenschonender Produkte erfordert den Einsatz digitaler Werkzeuge in der Designphase, der virtuellen Absicherung, der Fertigung und Qualitätsüberwachung sowie nachgelagerten Bauteilprüfung zur Abbildung der Nutzungsphase. Im Rahmen der Arbeiten wird daher der gesamte Produktentstehungs- und Prüfprozess betrachtet. Dies beinhaltet das Design im Kontext des konstruktiven Leichtbaus, den schweißtechnischen Fertigungsprozess, die Bauteilprüfung sowie den Transfer der Ergebnisse in die Industrie durch serientaugliche Demonstratoren. Der Fokus der Arbeiten ist, die Fertigung auch im Umfeld eines für großskalige Stahlstrukturen üblichen hohen Individualisierungsgrades schweißtechnisch zu automatisieren und das Leichtbaupotenzial gezielt umzusetzen. Die Vorgaben aus der Designphase hinsichtlich einer lastgerechten Gestaltung bzw. Implementierung bionischer Ansätze können so gezielt durch einen adaptiven, automatisierten Schweißprozess eingestellt werden. Dies führt zu einer Erhöhung der Ermüdungs¬festigkeit und damit Produktlebensdauer, wodurch die Strukturen dünnwandiger ausgeführt und Ressourcen sowie CO2 eingespart werden können. T2 - Sitzung des DVS Fachausschuss FA03 - Lichtbogenschweißen CY - Rostock, Germany DA - 11.10.2022 KW - Offshore Windenergieanlagen KW - Gründungsstrukturen KW - Leichtbau KW - Automatisierte schweißtechnische Fertigung PY - 2022 AN - OPUS4-56656 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Winterkorn, René A1 - Fabry, Çağtay A1 - Rethmeier, Michael A1 - Ratkovac, Mirjana A1 - Thiele, Marc A1 - Baeßler, Matthias T1 - Innovative Design- und Fertigungsstrategien zur Steigerung der Leichtbaupotenziale im Stahlbau N2 - Offshore wind energy plays an important role for the desired transition towards a carbon dioxide free industry within the next decades. However, the grounding of the offshore wind plants governs the overall installation process besides bureaucratic bottlenecks. The application of lightweight principles in steel construction, e.g. the usage dissolved load-bearing structures, so called Jackets foundations, offer great potential in reducing the resource consumption, especially with respect to the needed amount of steel. In this context this presentation focuses on a fully digitalization of the welding manufacturing and as well as testing chain to enable a fully automated manufacturing as well as quality assessment of tubular nodes as key element of Jackets foundation structures. Furthermore, the relationship between the seam shape geometry and resulting fatigue strength is evaluated by numerical methods incorporating bionic principles. It is shown that tubular nodes can be welded fully automatically taking geometry tolerances into account. Moreover, the seam shape could be manufactured as requested by the numerical models which offers great potential for an extended lifetime. Subsequently, the improvements in resource efficiency and reduction of carbon dioxide emissions are evaluated by a life-cycle-assessment. T2 - Leichtbau in der Hauptstadtregion - Rohstoffe - Recycling - Rohstoffe: Kreislaufwirtschaft im Leichtbau CY - Berlin, Germany DA - 28.11.2022 KW - Offshore Windenergie KW - Gründungsstrukturen KW - Leichtbau KW - Automatisierte schweißtechnische Fertigung PY - 2022 AN - OPUS4-56657 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Winterkorn, René A1 - Fabry, Çağtay A1 - Rethmeier, Michael A1 - Ratkovac, Mirjana A1 - Thiele, Marc A1 - Baeßler, Matthias T1 - Innovative Design- und Fertigungsstrategien zur Steigerung der Leichtbaupotenziale im Stahlbau N2 - Ziel des Verbundvorhabens „SmartWeld“ ist es, für die schweißtechnische Fertigung von Stahlbaustrukturen exemplarisch am Beispiel von Hohlprofilknoten, welche als designrelevante Elemente von Gründungsstrukturen für Offshore-Windenergieanlagen (OWEA) einsetzbar sind, die Möglichkeiten des Leichtbaus unter konsequenter Digitalisierung der Fertigungskette aufzuzeigen, um einerseits die Ressourceneffizienz zu forcieren und gleichzeitig wettbewerbsfähige Fertigungsstrategien aufzuzeigen. Innerhalb von „SmartWeld“ werden daher die Möglichkeiten einer wirtschaftlichen Fertigung von Leichtbau-Gründungsstrukturen am Beispiel aufgelöster Tragstrukturen (Jackets) aufgezeigt. Eine lastgerechte Auslegung der Schweißverbindungen nach bionischen Prinzipien ermöglicht, weitere Einsparpotenziale an Ressourcen bei gleichzeitiger Erhöhung der Lebensdauer zu erschließen. Die Ausnutzung konstruktiver Prinzipien des Leichtbaus zur Erzeugung innovativer und ressourcenschonender Produkte erfordert den Einsatz digitaler Werkzeuge in der Designphase, der virtuellen Absicherung, der Fertigung und Qualitätsüberwachung sowie nachgelagerten Bauteilprüfung zur Abbildung der Nutzungsphase. Im Rahmen der Arbeiten wird daher der gesamte Produktentstehungs- und Prüfprozess betrachtet. Dies beinhaltet das Design im Kontext des konstruktiven Leichtbaus, den schweißtechnischen Fertigungsprozess, die Bauteilprüfung sowie den Transfer der Ergebnisse in die Industrie durch serientaugliche Demonstratoren. Der Fokus der Arbeiten ist, die Fertigung auch im Umfeld eines für großskalige Stahlstrukturen üblichen hohen Individualisierungsgrades schweißtechnisch zu automatisieren und das Leichtbaupotenzial gezielt umzusetzen. Die Vorgaben aus der Designphase hinsichtlich einer lastgerechten Gestaltung bzw. Implementierung bionischer Ansätze können so gezielt durch einen adaptiven, automatisierten Schweißprozess eingestellt werden. Dies führt zu einer Erhöhung der Ermüdungs¬festigkeit und damit Produktlebensdauer, wodurch die Strukturen dünnwandiger ausgeführt und Ressourcen sowie CO2 eingespart werden können. T2 - 9. Forum Leichtbau - Fortschrittliche Fertigungstechnologien und Werkstoffe für den Klimaschutz CY - Berlin, Germany DA - 29.09.2022 KW - Offshore Windenergieanlagen KW - Gründungsstrukturen KW - Leichtbau KW - Bionik KW - Automatisierte schweißtechniche Fertigung PY - 2022 AN - OPUS4-56655 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fritzsche, André A1 - Hilgenberg, Kai A1 - Rethmeier, Michael T1 - Influence of welding parameters on electromagnetic supported degassing of die-casted and wrought aluminum N2 - The paper describes a systematic investigation of the EM influenced laser beam welding of the aluminum die casting alloy AlSi12(Fe) in comparison to a reference material, a wrought aluminum alloy AlMg3. By using of a face centred CCD test plan, the influencing variables laser power, welding velocity and magnetic flux density are varied with regard to their influence on the remaining porosity. The global pore fraction of the weld seams was analyzed by X-ray images with ImageJ. This enabled a qualitatively very good regression model to be derived for the respective material, which identifies the dominant influencing variables. The results prove, statistically verified, for the investigated parameter range, that - the magnetic flux density is the main cause for the porosity reduction, - the porosity rises with increasing laser power the porosity in the weld seams rises, - the influence of the welding velocity is negligible, - the pore quantity in wrought alloy is more strongly minimized by the magnetic flux density than in die casting, - the porosity decreases due to the EM influence by approx. 70 % compared to the unaffected welds. This effect is emphasized by the contour line charts, which illustrate the relationship between laser power and magnetic flux density. With the exception of the quadratic influence of B at the wrought alloy, the statistical correlation shows a linear development of the respective influence variables for both aluminum alloys. In order to investigate these deviations, further simulations with a focus on weld pool geometry and weld pool flow are to be performed. In addition, the welding results can be classified in accordance with DIN EN ISO 13919-2 in the highest evaluation group B for AlMg3 and in evaluation group C for AlSi12(Fe) by applying a magnetic flux density of 350 mT. The analysis of the CT images at constant laser power and welding velocity allows a direct comparison both between the two alloys and also as a function of the magnetic flux density with regard to the number and size of pores. An increase in the magnetic flux density leads to a significant decrease in the number and volume of pores, which can be seen more clearly in wrought alloy than in die casting. Very acceptable results can be achieved for both materials and different welding parameters. This successfully demonstrates the desired process robustness and functionality of the EM system for practical applications. For subsequent investigations of overlap joints, the lowest possible laser power and a high magnetic flux density are recommended. T2 - 38th International Congress on Applications of Lasers & Electro-Optics CY - Orlando, FL, USA DA - 07.10.2019 KW - AISI D2 KW - Laser implantation KW - Surface texturing KW - TiB2 PY - 2019 SN - 978-1-940168-1-42 SP - Paper Macro 1202 AN - OPUS4-50009 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fritzsche, André A1 - Hilgenberg, Kai A1 - Rethmeier, Michael T1 - Influence of welding parameters on electromagnetic supported degassing of die-casted and wrought aluminum N2 - Laser beam welding of aluminum die casting is challenging. A large quantity of gases (in particular, hydrogen) is absorbed by aluminum during the die-cast manufacturing process and is contained in the base material in solved or bound form. After remelting by the laser, the gases are released and are present in the melt as pores. Many of these metallurgic pores remain in the weld seam as a result of the high solidification velocities. The natural (Archimedean) buoyancy is not sufficient to remove the pores from the weld pool, leading to process instabilities and poor mechanical properties of the weld. Therefore, an electromagnetic (EM) system is used to apply an additional buoyancy component to the pores. The physical mechanism is based on the generation of Lorentz forces, whereby an electromagnetic pressure is introduced into the weld pool. The EM system exploits the difference in electrical conductivity between poorly conducting pores (inclusions) and the comparatively better conducting aluminum melt to increase the resulting buoyancy velocity of the pores. Within the present study, the electromagnetic supported degassing is investigated in dependence on the laser beam power, welding velocity, and electromagnetic flux density. By means of a design of experiments, a systematic variation of these parameters is carried out for partial penetration laser beam welding of 6mm thick sheets of wrought aluminum alloy AlMg3 and die-cast aluminum alloy AlSi12(Fe), where the wrought alloy serves as a reference. The proportion of pores in the weld seams is determined using x-ray images, computed tomography images, and cross-sectional images. The results prove a significant reduction of the porosity up to 70% for both materials as a function of the magnetic flux density. T2 - ICALEO 2019 CY - Orlando, FL, USA DA - 07.10.2019 KW - Laser beam welding KW - Electromagnetic supported degassing KW - Die-casted aluminum PY - 2020 DO - https://doi.org/10.2351/7.0000064 VL - 32 IS - 2 SP - 022031-1 EP - 022031-8 PB - AIP Publishing AN - OPUS4-50728 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael T1 - Influence of weld imperfections on the fatigue behaviour of resistance spot welded advanced high strength steels N2 - The influence of two different weld imperfections (gap/crack) on the fatigue behaviour of spot welded joints was tested Surface cracks havenoinfluenceon thefatiguelife Samples with cracks in the electrode indentation /HAZ where tested Stiffness curves are not significantly influenced by surface cracks 3D FE-Simulation demonstrate no changes of stress due to surface imperfections T2 - 11th International Fatigue Congress CY - Melbourne, Australia DA - 02.03.2014 KW - 3D FE-simulation KW - Cracks in the HAZ PY - 2014 AN - OPUS4-38343 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bakir, Nasim A1 - Üstündag, Ömer A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Influence of the weld pool geometry on solidification cracking in partial penetration high power laser beam welding N2 - Solidification cracking is still a serious problem in laser beam welding, especially in the welding of thick-walled plates. The influence of weld pool geometry on solidification cracking in partial penetration welding of thick plates is investigated within scope of this study. Therefore, a specific experimental setup of steel and quartz glass in butt configuration and on the side with high-speed camera were used to record the weld pool shape. In addition, the influence of laser inclination angle on the weld pool geometry and on solidification crack formation was investigated. The results show a bulge in the weld pool root, which is separated from an upper region by a necking region. This leads to a case where there are three different longitudinal region lengths with different solidification zones. This temporal sequence of solidification strongly promotes the formation of solidification cracks in the weld root. T2 - 12th CIRP Conference on photonic technologies (LANE 2022) CY - Fürth, Germany DA - 04.09.2022 KW - Laser beam welding KW - Partial penetration KW - Weld pool shape PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563940 DO - https://doi.org/10.1016/j.procir.2022.08.174 VL - 111 SP - 397 EP - 400 PB - Elsevier B.V. AN - OPUS4-56394 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, Xiangmeng A1 - Putra, Stephen Nugraha A1 - Bachmann, Marcel A1 - Artinov, Antoni A1 - Rethmeier, Michael T1 - Influence of the free surface reconstruction on the spatial laser energy distribution in high power laser beam welding modeling N2 - An accurate and efficient description of the spatial distribution of laser energy is a crucial factor for the modeling of laser material processing, e.g., laser welding, laser cutting, or laser-based additive manufacturing. In this study, a 3D heat transfer and fluid flow model coupled with the volume-of-fluid algorithm for free surface tracking is developed for the simulation of molten pool dynamics in high-power laser beam welding. The underlying laser-material interactions, i.e., the multiple reflections and Fresnel absorption, are considered by a raytracing method. Two strategies of free surface reconstruction used in the ray-tracing method are investigated: a typical piecewise linear interface calculation (PLIC)-based method and a novel localized level-set method. The PLIC-based method is discrete, resulting in noncontinuous free surface reconstruction. In the localized level-set method, a continuous free surface is reconstructed, and, thus, the exact reflection points can be determined. The calculated spatial laser energy distribution and the corresponding molten pool dynamics from the two methods are analyzed and compared. The obtained numerical results are evaluated with experimental measurements to assure the validity of the proposed model. It is found that distinct patterns of the beam multiple reflections are obtained with the different free surface reconstructions, which shows significant influence not only on the molten pool behaviors but also on the localized keyhole dynamics. KW - Laser beam welding KW - Laser energy distribution KW - Weld pool dynamics KW - Ray teacing PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-562429 DO - https://doi.org/10.2351/7.0000739 SN - 1042-346X VL - 34 IS - 4 SP - 042023-1 EP - 042023-8 PB - Laser Institute of America CY - Orlando, Fla. AN - OPUS4-56242 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bakir, Nasim A1 - Biltgen, J. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Influence of Partial Penetration Laser Hybrid Welding Parameters on the Solidification Cracking for Thick-Walled Structures N2 - In this study, the influence of the welding speed and the arc power on the solidification crack formation for partial penetration laser hybrid welded Thick-Walled plates were investigated. Experimentally, a linear correlation between the welding velocity and the crack number was observed. That is by reducing the welding velocity the crack number was reduced. The reduced welding velocity showed a strong impact on stress, as the model demonstrated a very lower stress amount in comparison to the reference case. The reduction of the welding speed could be a helpful technique to reduce the hot cracking. The wire feed speed showed a very slight influence on the crack formation. That can be returned to the large distance between the critical region for cracking and the arc region. T2 - Lasers in Manufacturing Conference 2019 CY - Munich, Germany DA - 24.06.2019 KW - Hybrid laser-arc welding KW - Solidification cracking KW - Thick-walled steel KW - Numerical simulation PY - 2019 SP - 1 EP - 7 PB - WLT Wissenschaftliche Gesellschaft Lasertechnik e.V AN - OPUS4-48733 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Üstündag, Ömer A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Influence of oscillating magnetic field on the keyhole stability in deep penetration laser beam welding N2 - The stability of the keyhole decreases for deep penetrated high-power laser beam welding. The keyhole tends to collapse with increasing laser power and e.g. keyhole induced porosity can occur. This study deals with the observation of the keyhole during high-power laser beam welding in partial penetration mode by means of a high-speed camera. A butt configuration of 25 mm thick structural steel and transparent quartz glass was used for the experiments. An oscillating magnetic field was applied perpendicular to the welding direction on the root side of the steel plate. The keyhole was highlighted with a coaxial diode laser. It was ascertained that the stability of the keyhole and the weld penetration depth were increased by applying an oscillating magnetic field with an oscillating frequency of 1.2 kHz and a magnetic flux density of 50 mT. KW - Magnetic field KW - Laser beam welding KW - Keyhole stability PY - 2021 DO - https://doi.org/10.1016/j.optlastec.2020.106715 SN - 0030-3992 VL - 135 SP - 106715 PB - Elsevier Ltd. AN - OPUS4-52007 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neubert, S. A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Influence of non-uniform martensitic transformation on residual stresses and distortion of GMA-welding N2 - A combined experimental and numerical approach is applied for a numerical analysis of the non-uniform martensitic transformation kinetic on welding residual stresses and distortion of a single pass weld. The (γ → α)-transformation kinetic within the weld pool region is governed by a non-uniform distribution of the elements chromium and nickel. The single-pass weld was performed by use of the low-alloyed high-strength steel S960QL with the high-alloyed high-strength filler wire CN 13/4-IG®. A thermo-mechanical FE model of the welding process was experimentally validated against temperature field, solid phase distribution, transformation behaviour, X-Ray stress measurements and transient optical distortion measurements. The experimentally determined and calculated weld residual stresses and transient distortion are in good agreement. It can be shown that the change on the (γ → α)-transformation kinetic driven by the inhomogeneous distribution of the chemical contents causes a strong influence on the weld residual stresses within the volume of the weld pool, which could promote crack propagation within the solidified weld pool by use of high-alloyed filler materials. Furthermore, a significant influence on the development of the transient welding distortion is visible. This influence should be respected during numerically calculation of welding distortion in case of multi-pass welding using interpass temperatures and high-alloyed filler materials. KW - Welding residual stresses KW - FEA KW - Welding simulation KW - Dissimilar welding KW - Transformable steels PY - 2017 DO - https://doi.org/10.1016/j.jcsr.2016.08.020 SN - 0143-974X SN - 1873-5983 VL - 128 SP - 193 EP - 200 PB - Elsevier Ltd. AN - OPUS4-37276 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Frei, Julian A1 - Rethmeier, Michael T1 - Influence of manufacturing conditions on the cracking susceptibility of AHSS during resistance spot welding N2 - The complex microstructure and the advanced mechanical properties of AHSS steel types lead to an increased susceptibility to weld cracking, especially during resistance spot welding under ‘rough’ manufacturing conditions. Various activities have been conducted in recent years at the Federal Institute for Materials Research and Testing (BAM) and the Fraunhofer IPK on this matter. Understandings about the safe spot weldability and the process of crack-forming itself were gained, and solutions for handling this issue given. The performed work includes investigations on the influence of initial gaps as well as restraint intensity. An experimental method for the determination of the general cracking susceptibility, i.e. a material ranking of AHSS in respective to current restraints was developed. Coupled mechanical and thermal simulations of the welding process show the present internal stress-strain-conditions and values responsible for the formation of cracks, deepening the understanding of the process. By using this easy to perform and material-independent method for the determination of the cracking susceptibility in resistance spot welded joints, small and medium sized companies can profit by rapidly evaluating the joinability of their handled material combinations as well as OEMs. T2 - Sheet Metal Welding Conference XVII CY - Livonia, Michigan, USA DA - 18.10.2016 KW - Welding under external loading KW - Cracking susceptibility of AHSS KW - Resistance spot welding KW - Initial gap PY - 2016 SP - Session 1-2, 1 EP - Session 1-2, 15 AN - OPUS4-38137 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael T1 - Influence of manufacturing conditions on the cracking susceptibility of AHSS during resistance spot welding N2 - The influence of two different weld imperfections (gap/crack) on the fatigue behaviour of spot welded joints was tested Surface cracks have no influence on the fatigue life Samples with cracks in the electrode indentation /HAZ where tested Stiffness curves are not significantly influenced by surface cracks 3D FE-Simulation demonstrate no changes of stress due to surface imperfections • Welding under external forces was found suitable for characterizing AHSS materials New quick and easy-to-perform procedure for establishing a material ranking regarding cracking susceptibility T2 - AWS Sheet Metal Welding Conference XVII CY - Livonia, MI, USA DA - 19.10.2016 KW - 3D-FE-Simulation PY - 2016 AN - OPUS4-38366 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Raute, J. A1 - Jokisch, T. A1 - Marko, A. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Influence of electron beam welding parameters on the weld seam geometry of Inconel718 at low feed rates N2 - Ni-based superalloys are well established in various industrial applications, because of their excellentmechanical properties and corrosion resistance at high temperatures. Despite the high development stage anda common industrial use of these alloys, hot cracking remains a major challenge limiting the weldability ofthe materials. As commonly known, the hot cracking susceptibility during welding increases with the amountof precipitation phases. Hence, a large amount of highstrength Ni-Alloys is rated as non-weldable. A newapproach based on electron beam welding at low feed rates shows great potential for reducing the hotcracking tendency of precipitation-hardened alloys. However, geometry and properties of the weld seamdiffer significantly in comparison to the common process range for practical uses. The aim of this study is toinvestigate the influence of welding parameters on the seam geometry at low feed rates between 1 mm/s and10 mm/s. For this purpose, 25 bead on plate welds on a 12 mm thick sheet made of Inconel 718 are carriedout. First, the relevant parameters are identified by performing a screening. Then the effects discovered arefurther studied by using a central composite design. The results show a significant difference between theanalyzed weld seam geometry in comparison to the well-known appearance of electron beam welded seams. KW - Electron beam welding KW - Ni-based superalloy KW - Inconel 718 KW - Low feed rates KW - Seam geometry KW - Hot crack PY - 2020 DO - https://doi.org/10.3139/120.111614 SN - 0025-5300 VL - 62 IS - 12 SP - 1221 EP - 1227 PB - Carl Hanser Verlag GmbH & Co. KG CY - München AN - OPUS4-52016 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Straße, Anne A1 - Rethmeier, Michael A1 - Gumenyuk, Andrey T1 - Influence of edge‑deposited layers on mechanical and corrosion properties of laser beam welds of 15 mm thick AISI 2205 duplex stainless steel N2 - AISI 2205 duplex stainless steel is used in a variety of industries, including the chemical and petrochemical industries. This is due to its high tensile strength combined with good ductility and corrosion resistance. However, in laser beam welding, these properties are negatively afected by the high cooling rates typical of the welding process. The resulting higher ferrrite content in the weld metal than in the base material leads to a reduction in the ductility and corrosion resistance of the welded joint. To overcome this problem, in this study, thick plates were coated by direct energy deposition (DED) prior to laser beam welding, whereas a duplex powder mixture containing a higher nickel concentration was used as a coating material. To improve the weld quality for the proposed two-step process, a method of additional material deposition instead of conventional tack weld was investigated. The resulting welded joints showed a well-balanced austenite to ferrite ratio and their properties and microstructure were verifed by metallographic analysis, electron backscatter difraction and Charpy impact testing. Using the standard ASTM G48 test method, it was found that the corrosion resistance of the welds was improved by a factor of four in average compared to the conventionally welded joints. The resulting properties, such as good ductility and corrosion resistance, of the welds with pre-coated edges showed good agreement with those of the base metal and confrmed the proposed two-step process as a promising alternative to the conventional approaches for welding thick duplex stainless steel plates. KW - Laser metal deposition KW - Laser beam welding KW - Duplex steels PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-581731 UR - https://rdcu.be/dlb6E DO - https://doi.org/10.1007/s40194-023-01567-7 SN - 0043-2288 SP - 1 EP - 12 PB - Springer AN - OPUS4-58173 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Üstündag, Ömer A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Influence of an external applied AC magnetic field on the melt pool dynamics at high-power laser beam welding N2 - The study deals with the determination of the influence of an externally applied oscillating magnetic field on the melt pool dynamics in high power laser beam and hybrid laser arc welding processes. An AC magnet was positioned under the workpiece which is generating an upward directed electromagnetic force to counteract the formation of the droplets. To visualise the melt flow characteristics, several experiments were carried out using a special technique with mild steel from S355J2 with a plate thickness of up to 20 mm and a quartz glass in butt configuration. The profile of the keyhole and the melt flow were recorded with a highspeed camera from the glass side. Additionally, the influence of the magnetic field orientation to the welding direction on the filler material dilution on laser hybrid welding was studied with variating oscillation frequency. The element distribution over the whole seam thickness was measured with X-ray fluorescence (XRF). The oscillation frequency demonstrated a great influence on the melt pool dynamics and the mixing of the elements of the filler wire. The highspeed recordings showed, under the influence of the magnetic field, that the melt is affected under strong vortex at the weld root, which also avoids the formation of droplets. T2 - 18th Nordic Laser Materials Processing Conference (18th NOLAMP) KW - Laser beam welding KW - AC magnetic field KW - Melt pool dynamics KW - Filler wire mixing PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-539231 DO - https://doi.org/10.1088/1757-899X/1135/1/012017 VL - 1135 IS - 012017 SP - 1 EP - 10 PB - IOP Publishing AN - OPUS4-53923 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sproesser, G. A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Increasing performance and energy efficiency of Gas Metal Arc Welding by a high power tandem process N2 - Standard Gas Metal Arc Welding (Standard GMAW) and a high power Tandem GMAW (TGMAW) process are evaluated with respect to energy efficiency. Current, voltage and overall equipment power are measured and energy consumption is determined. The new key performance indicator Electrical Deposition Efficiency is introduced to reflect the energy efficiency of GMAW processes. Additionally, wallplug efficiency of the equipment is determined in order to identify the overall energy consumption. Results show that energy efficiency as well as economic process performance can be significantly increased by application of the TGMAW process. Furthermore findings indicate that wall-plug efficiency of the equipment is independent of power level and material transfer mode. A metal plate of 30 mm thick structural steel is joined by Standard GMAW and TGMAW to demonstrate the total energy savings for a real weld. Electricity consumption is reduced by more than 20 % using the high power TGMAW process. T2 - 13th Global Conference on Sustainable Manufacturing - Decoupling Growth from Resource Use CY - Bình Dương New City, Vietnam DA - 16.09.2015 KW - Thick metal plate welding KW - Energy efficiency KW - Tandem Gas Metal Arc Welding KW - High power welding PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-353762 DO - https://doi.org/10.1016/j.procir.2016.01.148 SN - 2212-8271 VL - 40 SP - 643 EP - 648 PB - Elsevier B.V. AN - OPUS4-35376 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Scheuschner, Nils A1 - Altenburg, Simon A1 - Pignatelli, Giuseppe A1 - Gornushkin, Igor B. A1 - Baensch, Franziska A1 - Rethmeier, Michael T1 - In-situ Prozessüberwachung beim Laser-Pulver-Auftragschweißen (LPA) mittels Thermografie, optischer Emissionsspektroskopie (OES) und Schallemissionsanalyse (SEA) N2 - Vor allem in den letzten Jahren ist das Interesse der Industrie an der additiven Fertigung deutlich gestiegen. Die Vorteile dieser Verfahren sind zahlreich und ermöglichen eine ressourcenschonende, kundenorientierte Fertigung von Bauteilen, welche zur stetigen Entwicklung neue Anwendungsbereiche und Werkstoffe führen. Aufgrund der steigenden Anwendungsfälle, nimmt auch der Wunsch nach Betriebssicherheit unabhängig von anschließenden kostenintensiven zerstörenden und zerstörungsfreien Prüfverfahren zu. Zu diesem Zweck werden im Rahmen des von der BAM durchgeführten Themenfeldprojektes „Prozessmonitoring in Additive Manufacturing“ verschiedenste Verfahren auf ihre Tauglichkeit für den in-situ Einsatz bei der Prozessüberwachung in der additiven Fertigung untersucht. Hier werden drei dieser in-situ Verfahren, die Thermografie, die optische Emissionsspektroskopie und die Schallmissionsanalyse für den Einsatz beim Laser-Pulver-Auftragschweißen betrachtet. T2 - 41. Assistentenseminar der Füge- und Schweißtechnik CY - Magdeburg, Germany DA - 02.09.2020 KW - Laser-Pulver-Auftragschweißen (LPA) KW - Thermographie KW - Optische Emissionsspektroskopie (OES) KW - Schallemissionsanalyse (SEA) PY - 2021 SN - 978-3-96144-141-9 VL - 370 SP - 132 EP - 140 PB - DVS MEdia CY - Düsseldorf AN - OPUS4-53967 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Biegler, M. A1 - Graf, B. A1 - Rethmeier, Michael T1 - In-situ distortions in LMD additive manufacturing walls can be measured with digital image correlation and predicted using numerical simulations N2 - Distortions in Additive Manufacturing (AM) Laser Metal Deposition (LMD) occur in the newly-built component due to rapid heating and solidification and can lead to shape deviations and cracking. This paper presents a novel approach to quantify the distortions experimentally and to use the results in numerical simulation validation. Digital Image Correlation (DIC) is applied together with optical filters to measure in-situ distortions directly on a wall geometry produced with LMD. The wall shows cyclic Expansion and shrinking with the edges bending inward and the top of the sample exhibiting a slight u-shape as residual distortions. Subsequently, a structural Finite Element Analysis (FEA) of the experiment is established, calibrated against experimental temperature profiles and used to predict the in-situ distortions of the sample. A comparison of the experimental and numerical results reveals a good agreement in length direction of the sample and quantitative deviations in height direction, which are attributed to the material model used. The suitability of the novel experimental approach for measurements on an AM sample is shown and the potential for the validated numerical model as a predictive tool to reduce trial-and-error and improve part quality is evaluated. KW - Laser metal deposition KW - DIC KW - Dimensional accuracy KW - AM KW - Welding simulation PY - 2018 DO - https://doi.org/10.1016/j.addma.2017.12.007 SN - 2214-8604 SN - 2214-7810 VL - 20 SP - 101 EP - 110 PB - Elsevier AN - OPUS4-43776 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Pavlov, V. A1 - Volvenko, S. A1 - Rethmeier, Michael T1 - In situ determination of the critical straining condition for solidification cracking during laser beam welding N2 - A self-restraint hot cracking test (free edge test) was used in combination with a novel optical measurement technique to determine the critical straining conditions for solidification cracking for the stainless steel grade 1.4828 (AISI 309). The Lucas-Kanade algorithm for the optical flow (OF) calculation was implemented to obtain the full-field displacement and then the full-field strain. The use of external laser illumination with appropriate filters allows to obtain good image quality with good contrast. The critical straining conditions required for solidification cracking can be obtained by means the proposed technique in the immediate vicinity of the solidification front. A very good repeatability was demonstrated for the used measurement technique. The critical straining conditions for solidification cracking for the tested steel und under this welding conditions has been detected KW - Laser beam welding KW - Solidification cracking KW - Critical strain KW - Critical strain rate KW - Optical flow PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-513070 DO - https://doi.org/10.1016/j.procir.2020.09.104 SN - 2212-8271 VL - 94 SP - 666 EP - 670 PB - Elsevier AN - OPUS4-51307 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Churiaque, C. A1 - Sanchez-Amaya, J.M. A1 - Üstündag, Ömer A1 - Porrua-Lara, M. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Improvements of hybrid laser arc welding for shipbuilding T-joints with 2F position of 8 mm thick steel N2 - the joints throughout the structure. The flat units are constituted by butt welded flat plates, on which longitudinal T-welded reinforcements are placed to rigidize the structure. Among the different welding technologies, Hybrid Laser Arc Welding (HLAW) is becoming a mature process, profitable and highly productive. In addition, more innovative welding equipment are being developed nowadays, offering greater work flexibility, and raising expectations of achieving better quality, and economic viability. Another key point of HLAW to keep in mind is that structural distortions are reduced, resulting in decreasing the cost and time of straightening work. In the present contribution, the influence of HLAW parameters on the quality of fillet joints of naval steel has been analysed. Experimental HLAW tests were performed with a high power disk laser to join EH36 naval steel plates, with a T configuration. The influence of different processing parameters has been analysed, as the laser power, welding speed, wire feed rate and the configuration of the HLAW processes (including head angle and laser/arc leading process). In addition, FEM simulations were carried out in order to estimate residual stresses and distortion of welded part. The distortion values provided by FEM presented excellent agreement with the measured experimental results. To evaluate the welds, non destructive tests including X-ray tests, metallographic analysis of cross sections, and microhardness mapping tests were performed. Full penetration 8 mm T welds were obtained for the first time at an industrially applicable 2F position with a reasonable HLAW head angle, in one single step without sealing root, and using zero gap square groove Edge preparation. The present contribution presents welding rates up to 2.2 m/min for 2F T-joints of this steel thickness, a much higher processing velocity than previously reported for industrial applications. KW - Hybrid laser arc welding PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-528410 DO - https://doi.org/10.1016/j.optlastec.2021.107284 VL - 143 SP - 1 EP - 20 PB - Elsevier Ltd. AN - OPUS4-52841 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Biegler, M. A1 - Khazan, P. A1 - Gazen, M. A1 - Rethmeier, Michael T1 - Improvement of numerical simulation model setup and calculation time in additive manufacturing-laser-metal-deposition components with an advanced modelling strategy N2 - Rapid localized heating and cooling during additive manufacturing using laser deposition method (LMD) lead to loss of dimensional accuracy as well as cracking of built parts. Finite-Element welding simulations allow prediction of geometrical deviations and accumulated residual stresses as well as their optimization before conducting experiments. Due to the great length of stacked welds, calculation times for fully transient thermomechanical simulations are currently long, the calculation stability suffers from the high number of contact bodies in the model and the modelling effort is high, as the geometries need to be sliced and positioned layer-wise. In this contribution, an integrated modelling approach is demonstrated for a thin-walled LMD component made from 30 layers of 1.4404 (316L) stainless steel: Instead of the layer-by-layer modelling strategy commonly found in the literature, the whole component mesh is kept in one piece and the fully transient, layer-by-layer material deposition is implemented via element sets. In contrast to prior simulations, nonlinear contact between the layers does not have to be considered, significantly decreasing calculation times. The calculated distortions are compared to recently published, in-situ digital image correlation (DIC) measurements as well as numerical simulations conducted with the established layer-wise modelling strategy to judge result quality. Finally, the improvement in calculation time and ease-of-use is compared between both modelling approaches and conclusions regarding future usage for industrial-scale components are drawn. T2 - 12th International Seminar ‘Numerical Analysis of Weldability' CY - Graz, Austria DA - 23.09.2018 KW - Additive Manufacturing KW - Laser Metal Deposition KW - Distortion simulation KW - Calculation time KW - Directed energy deposition KW - Efficient modelling PY - 2019 SN - 978-3-85125-615-4 SN - 978-3-85125-616-1 DO - https://doi.org/10.3217/978-3-85125-615-4-52 SN - 2410-0544 VL - 2019 SP - 979 EP - 1003 PB - Verlag der Technischen Universität Graz CY - Graz AN - OPUS4-49274 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Üstündag, Ö. A1 - Avilov, V. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Improvement of Filler Wire Dilution Using External Oscillating Magnetic Field at Full Penetration Hybrid Laser-Arc Welding of Thick Materials N2 - Hybrid laser-arc welding offers many advantages, such as deep penetration, good gap bridge-ability, and low distortion due to reduced heat input. The filler wire which is supplied to the process is used to influence the microstructure and mechanical properties of the weld seam. A typical problem in deep penetration high-power laser beam welding with filler wire and hybrid laser-arc welding is an insufficient mixing of filler material in the weld pool, leading to a non-uniform element distribution in the seam. In this study, oscillating magnetic fields were used to form a non-conservative component of the Lorentz force in the weld pool to improve the element Distribution over the entire thickness of the material. Full penetration hybrid laser-arc welds were performed on 20-mm-thick S355J2 steel plates with a nickel-based wire for different arrangements of the oscillating magnetic field. The Energy-dispersive X-ray spectroscopy (EDS) data for the distribution of two tracing elements (Ni and Cr) were used to analyze the homogeneity of dilution of the filler wire. With a 30° turn of the magnetic field to the welding direction, a radical improvement in the filler material distribution was demonstrated. This would lead to an improvement of the mechanical properties with the use of a suitable filler wire. KW - Thick materials KW - Hybrid laser-arc welding KW - Oscillating magnetic field KW - Electromagnetic stirring KW - Full penetration PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-489644 DO - https://doi.org/10.3390/met9050594 SN - 2075-4701 VL - 9 IS - 5 SP - 594 PB - Multidisciplinary Digital Publishing Institute CY - Basel AN - OPUS4-48964 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Üstündag, Ömer A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Improvement of Charpy impact toughness by using an AC magnet backing system for laser hybrid welding of thick S690QL steels N2 - The study deals with the influence of the heat input and the resulting cooling times on the microstructure and Charpy impact toughness of single-pass laser hybrid welded 20-mm thick high-strength steel S690QL. The main focus is on the change of the mechanical properties over the entire seam thickness. The cooling times were measured in-situ using a pyrometer and an optical fibre in three different depths of the seam where Charpy impact test specimens were also later taken. Thereby, three different heat inputs from 1.3 kJ/mm to 2 kJ/mm were investigated. Despite the observed decreased values of both t8/5-cooling time and the Charpy impact toughness in the root part of the seam, the required impact toughness of 38 J/cm2 could be reached in dependance on applied heat input, especially at the heat input of 1.6 kJ/mm. T2 - 12th CIRP conference on photonic technologies [lane 2022] CY - Fürth, Germany DA - 04.09.2022 KW - Thick-plate welding KW - Laser hybrid welding KW - Electromagnetic backing KW - Charpy impact toughness KW - Thermal cycles PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563731 DO - https://doi.org/10.1016/j.procir.2022.08.067 VL - 111 SP - 462 EP - 465 PB - Elsevier B.V. AN - OPUS4-56373 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fu, B. A1 - Shen, J. A1 - Suhuddin, U. A1 - Chen, T. A1 - dos Santos, J. A1 - Klusemann, B. A1 - Rethmeier, Michael T1 - Improved mechanical properties of cast Mg alloy welds via texture weakening by differential rotation refill friction stir spot welding N2 - Cast magnesium alloys welds produced by refill friction stir spot welding (refill FSSW) show low lap shear strength (LSS) and constantly fail in stirred zone (SZ) shear mode. The cause is most probably related to the heavily textured microstructure. Here, to re-engineer the resulting microstructure, we pro- pose a novel process variant, the differential rotation refill FSSW (DR-refill FSSW). DR-refill FSSW stim- ulates discontinuous dynamic recrystallization and produces a bimodal microstructure with weakened texture. Therefore, the deformation incompatibility between SZ and thermal-mechanically affected zone is avoided. The welds have 50% higher LSS than that of standard refill FSSW welds, and fail in a different failure mode, i.e., SZ pull-out mode. DR-refill FSSW provides a new and effective strategy for improving the performance of spot welds based on microstructural engineering. KW - Refill friction stir spot welding KW - Magnesium Alloy KW - Texture KW - EBSD KW - Plastic deformation PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-536885 DO - https://doi.org/10.1016/j.scriptamat.2021.114113 SN - 1359-6462 VL - 203 SP - 114113 PB - Elsevier Ltd. AN - OPUS4-53688 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -