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, 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 - CONF A1 - Neubert, S. A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Numerical Sensitivity Analysis of TRIP-Parameter K on Weld Residual Stresses and Weld Distortion N2 - A combined experimental numerical approach is applied for a sensitivity analysis of the transformation induced plasticity (TRIP)-parameter K on welding residual stresses and welding distortion for the welding of the low-alloyed high-strength S960QOL with the high-alloyed hig-strength filler material CN13-4-IG. A thermo-mechanical FE model of a real GMA welding process was experimentally validated against termperature field, X-Ray stress measurments and optical distortion measurement. Within the sensititvity analysis K was varied and the influence on the calculated welding residual stresses and welding distortion is evaluated by performing corresponding FEA. The correct order of K magnitude is necessary in order to reproduce the residual stresses qualitatively and quantitatively. For the sufficient reproducing of the welding distortion the transformation induced plasticity can be neglected. T2 - 11th International Seminar - Numerical Analysis of Weldability CY - Graz, Austria DA - 27.09.2015 KW - TRIP PY - 2016 SN - 978-3-85125-490-7 SN - 2410-0544 SP - 361 EP - 383 PB - Verlag der Technischen Universität Graz CY - Graz AN - OPUS4-38904 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinze, Christoph A1 - Schwenk, Christopher A1 - Rethmeier, Michael A1 - Caron, J. T1 - Numerical sensitivity analysis of welding-induced residual stress depending on variations in continuous cooling transformation behavior N2 - The usage of continuous cooling transformation (CCT) diagrams in numerical welding simulations is state of the art. Nevertheless, specifications provide limits in chemical composition of materials which result in different CCT behavior and CCT diagrams, respectively. Therefore, it is necessary to analyze the influence of variations in CCT diagrams on the developing residual stresses. In the present paper, four CCT diagrams and their effect on numerical calculation of residual stresses are investigated for the widely used structural steel S355J2 + N welded by the gas metal arc welding (GMAW) process. Rather than performing an arbitrary adjustment of CCT behavior, four justifiable data sets were used as input to the numerical calculation: data available in the Sysweld database, experimental data acquired through Gleeble dilatometry tests, and TTT/CCT predictions calculated from the JMatPro and Edison Welding Institute (EWI) Virtual Joining Portal software. The performed numerical analyses resulted in noticeable deviations in residual stresses considering the different CCT diagrams. Furthermore, possibilities to improve the prediction of distortions and residual stress based on CCT behavior are discussed. KW - Welding simulation KW - GMAW KW - CCT sensitivity KW - Welding residual stress PY - 2011 DO - https://doi.org/10.1007/s11706-011-0131-7 SN - 1673-7377 SN - 1673-7482 VL - 5 IS - 2 SP - 168 EP - 178 PB - Springer ; [Beijing] : Higher Education Press CY - Secaucus, N.J. ; Heidelberg AN - OPUS4-23835 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bachmann, Marcel A1 - Avilov, Vjaceslav A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Numerical simulation of electromagnetic melt control systems in high power laser beam welding N2 - The availability of laser sources with a power of 20 kW upwards prepared the ground for laser beam welding of up to 20 mm thick metal parts. Challenges are the prevention of gravity-driven melt drop-out and the control of the dynamics mainly due to the Marangoni flow. Coupled numerical turbulent fluid flow, thermal and electromagnetic simulations and experimental validation with aluminum AlMg3 and stainless steel AISI 304 were done for alternating and steady magnetic fields perpendicular to the process direction. The first can prevent melt sagging in full-penetration welding by Lorentz forces in the melt induced by an AC magnet located below the weld specimen counteracting gravitational forces. The latter controls the Marangoni flow by Lorentz braking forces in the melt by the so-called Hartmann effect. The simulations show that the drop-out of aluminum and stainless steel can be avoided for 20 mm thick fullpenetration welds with moderate magnetic flux densities of 70 mT and 95 mT at oscillation frequencies of 450 Hz and 3 kHz, respectively. The experiments are in good agreement but show somewhat larger values for steel, whose weakly ferromagnetic properties are a possible reason. The investigations with steady magnetic fields reveal the possibility to mitigate the dynamics significantly beginning with around 500 mT at laser penetration depths of approximately 20 mm. T2 - ICALEO 2013 - 32nd International congress on applications of lasers & electro-optics CY - Miami, FL, USA DA - 2013-10-06 KW - Laser beam welding KW - Electromagnetic weld pool support KW - Hartmann effect PY - 2013 SN - 978-0-912035-98-7 IS - Paper 401 SP - 50 EP - 59 AN - OPUS4-29466 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael ED - Bakir, Nasim T1 - Numerical simulation of solidification crack formation during laser beam welding of austenitic stainless steels under external load N2 - Solidification cracking phenomena taking place under Controlled Tensile Weldability (CTW) test conditions have already been investigated both experimentally and numerically via FEA in order to get a better understanding of the mechanisms of hot crack formation during laser beam welding of austenitic steel grades. This paper develops a three dimensional finite element model employing the contact elements technique to simulate the formation and propagation of solidification cracks during laser full penetration welding of fully austenitic stainless steel 1.4376. During the experimental procedure the resulting strain and displacement directed to the laser beam in the Close vicinity of the weld pool was measured at the surface of the workpiece using a Digital Image Correlation (DIC) technique with an external diode laser as an illuminating source. Local strain fields, global loads and crack lengths predicted by the model are in good Agreement with those observed in experiments. T2 - The 3rd IIW South‐East European Welding Congress CY - Timisoara, Romania DA - 03.06.2015 KW - Solidification cracking KW - DIC technique KW - Laser beam welding KW - Contact element KW - FEA PY - 2015 SN - 978-606-554-955-5 SP - 1 EP - 6 CY - Timisoara, Romania AN - OPUS4-36519 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lange, Fritz A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Rethmeier, Michael A1 - Hilgenberg, Kai T1 - Numerical simulation of the weld pool dynamics during pulsed laser welding using adapted heat source models N2 - A transient simulation including the impact of the laser energy, the melting of the metal and the development of the weld pool was conducted to observe the evolution of the vapor capillary and the solidification of the melt in pulsed laser beam welding of AISI 304 steel. The phase field method was implemented to investigate the evolution and behavior of the liquid-gas interface during welding and to describe the condensed and vapor phases. The effects of phase transition, recoil pressure, thermo-capillary and natural convection, vaporization and temperature dependent material properties were taken into account. A Gaussian-like heat source under consideration of the Fresnel absorption model was used to model the energy input of the laser beam. The heat source model was extended by a newly developed empirical approach of describing multiple beam reflections in the keyhole. To validate this new model, the numerical results were compared to experimental data and good agreement regarding the size and shape of the weld pool was observed. T2 - LANE Conference 2018 CY - Fürth, Germany DA - 03.09.2018 KW - Pulsed laser beam welding KW - Weld pool dynamics KW - Multiple reflections KW - Vaporization PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-458749 DO - https://doi.org/10.1016/j.procir.2018.08.044 SN - 2212-8271 VL - 74 SP - 679 EP - 682 PB - Elsevier Ltd. CY - Amsterdam [u.a.] AN - OPUS4-45874 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, Xiangmeng A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Numerical study of additional element transport in wire feed laser beam welding N2 - The transport phenomena in the wire feed laser beam welding are investigated numerically. A three-dimensional transient heat transfer and fluid flow model coupled with free surface tracing and element transport is developed. A ray-tracing method with local grid refinement algorithm is used to calculate the multiple reflections and Fresnel absorption on the keyhole wall. The filler material flows backward along the lateral side of the weld pool, and subsequently flows forward along the longitudinal plane. The occurrence of the bulging phenomenon may further prevent the downward transfer of the additional elements to the root of the weld pool. KW - Laser beam welding KW - Element transport KW - Filler wire KW - Numerical modelling PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-513271 DO - https://doi.org/10.1016/j.procir.2020.09.129 VL - 94 SP - 722 EP - 725 PB - Elsevier B.V. AN - OPUS4-51327 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bachmann, Marcel A1 - Artinov, Antoni A1 - Meng, Xiangmeng A1 - Rethmeier, Michael T1 - Numerical study of the bulging effect in deep penetration laser beam welding N2 - This article is devoted to the study of the bulging effect in deep penetration laser beam welding. The numerical results of the investigations are based upon experimental results from previous studies to reveal the relationship between the bulging effect and the hot cracking formation, as well as the mixing of alloying elements in the weld pool. The widening of the molten pool in its center area can be observed in full penetration as well as in partial penetration welds on 8 mm and 12 mm thick structural steel plates, respectively. The weld pool shape is extracted from the simulations to evaluate the extent of the necking of the solidification line as well as the bulging phenomena and its influence on the hot cracking phenomena. Relying on an earlier numerical study utilizing a fixed keyhole, simulation models considering a dynamic keyhole are developed thereto. Additionally, the mixing behavior of alloying elements during partial penetration is investigated. The link between the bulge and the studied phenomena is found to be significant. T2 - Lasers in Manufacturing Conference 2021 CY - Online meeting DA - 21.06.2021 KW - Deep penetration laser beam welding KW - Welding simulation KW - Solidification cracking KW - Bulging effect PY - 2021 SP - 1 EP - 8 AN - OPUS4-52848 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Artinov, Antoni A1 - Meng, Xiangmeng A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Numerical study on the formation of a bulging region in partial penetration laser beam welding N2 - A transient three-dimensional thermo-fluid dynamics numerical model was developed to study the formation of a bulging region in partial penetration laser beam welding. The model accounts for the coupling between the fluid flow, the heat transfer, and the keyhole dynamics by considering the effects of multiple reflections and Fresnel absorption of the laser beam in the keyhole, the phase transitions during melting and evaporating, the thermo-capillary convection, the natural convection, and the phase-specific and temperature-dependent material properties up to the evaporation temperature. The validity of the model was backed up by experimentally obtained data, including the drilling time, the weld pool length, the local temperature history outside the weld pool, the process efficiency, and a range of metallographic crosssections. The model was applied for the cases of partial penetration laser beam welding of 8 mm and 12 mm thick unalloyed steel sheets. The obtained experimental and numerical results reveal that the bulging region forms transiently depending on the penetration depth of the weld, showing a tendency to transition from a slight bulging to a fully developed bulging region between penetration depths of 6 mm and 9 mm, respectively. T2 - 13th International Seminar "Numerical Analysis of Weldability" CY - Seggau, Austria DA - 04.09.2022 KW - Laser beam welding KW - Deep penetration KW - Bulge formation KW - Numerical modeling PY - 2023 SN - 978-3-85125-968-1 SN - 978-3-85125-969-8 SN - 2410-0544 VL - 13 SP - 101 EP - 126 PB - Verlag der Technischen Universität Graz AN - OPUS4-58802 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - El-Sari, B. A1 - Biegler, M. A1 - Graf, B. A1 - Rethmeier, Michael T1 - Numerische Simulation einer AM-Prozesskette im DED Auftragschweißen N2 - Das DED Auftragschweißen ist ein additives Fertigungsverfahren für Metalle, bei dem das Material schichtweise auf ein Substrat aufgetragen wird. Die schnellen Temperaturzyklen rufen Spannungsgradienten im Bauteil hervor. Der schichtweise Aufbau der Bauteile verursacht eine anisotrope Mikrostruktur. Mittels nachgelagerter Wärmebehandlung können diese Effekte verringert werden. Im anschließenden Schritt der Prozesskette wird das additiv hergestellte Bauteil mittels Drahterodieren von dem Substrat abgetrennt. In diesem Beitrag wird eine thermo-mechanische Simulation der gesamten Prozesskette vorgestellt, welche den additiven Aufbau, Wärmebehandlung und das Abtrennen vom Substrat beinhaltet. Anstelle der in der Literatur üblichen schichtweisen Modellierungsstrategie für die DED Simulation wird das gesamte Bauteil in einem Stück vernetzt und der vollständig transiente, schichtweise Materialauftrag über Elementgruppen realisiert. Im Gegensatz zu früheren Simulationen muss der nichtlineare Kontakt zwischen den Schichten nicht berücksichtigt werden, was die Rechenzeiten deutlich verkürzt. Das Modell wurde validiert mittels Abgleiches des Verzugs aus Simulation und Experiment. Die Proben, bestehend aus DIN 1.4404 (AISI 316L), wurden nach jedem Prozessschritt 3D gescannt um den Verzug zu quantifizieren. Zusätzlich wurden Querschnitte und Härtetests nach Vickers von unterschiedlich behandelten Proben durchgeführt, um den Effekt der Wärmebehandlung auf die Mikrostruktur und die Härte des Bauteils zu untersuchen. T2 - 20. Roundtable Simulating Manufacturing CY - Marburg, Germany DA - 22.05.2019 KW - Numerische ISmulation KW - DED KW - AM KW - Laser-Pulver-Auftragschweißen PY - 2019 SP - 1 EP - 14 AN - OPUS4-50046 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Numerische Simulation im 3D-Druck N2 - Die numerische Simulation hilft, Probleme bei additiven Bauprozessen früh zu erkennen und Optimierungspotentiale auszuschöpfen. Ziel ist, im additiven Auftragschweißen (DED) die Zahl der nötigen Versuche durch Vorhersagen zu verringern und Prozessgrößen zu visualisieren. Eine besondere Anwendung der Simulation ist die Generierung verzugskompensierter Geometrien: Durch die Berechnung des Bauteilverzugs kann die Geometrie vor dem Bauen so verändert werden, dass sie mit Verzug die gewünschte Toleranz erreicht. So kann Zerspanvolumen und Aufmaß reduziert werden. KW - Schweißsimulation KW - FEM KW - Auftragschweißen KW - Additive Fertigung KW - Verzug PY - 2020 IS - 4 SP - 45 EP - 48 AN - OPUS4-51097 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bakir, Nasim A1 - Üstündag, Ömer A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Observation of the weld pool shape in partial penetration welding and its influence on solidification crack formation for high-power laser beam welding N2 - In this study, steel-glass experiments were conducted to observe the melt pool geometry using a high-speed camera. The high-speed recordings and optical flow analysis show that two main flows take place in form of vortices. The lower vortex drives the melt backwards from the front keyhole wall and thus causes an extension of the melt pool, which is called bulging. This bulging promotes solidification cracking by forming a closed area filled with melt and the accumulation of impurities in the final solidification phase, resulting in low-melting phases which are under tensile stress at the end of solidification. T2 - Lasers in Manufacturing Conference 2021 CY - Online meeting DA - 21.06.2021 KW - Laser beam welding KW - Weld pool shape KW - Solidification craking KW - Partial penetration PY - 2021 SP - 1 EP - 5 AN - OPUS4-53587 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Meng, Xiangmeng A1 - Karkhin, V. A1 - Rethmeier, Michael T1 - On the relationship between the bulge effect and the hot cracking formation during deep penetration laser beam welding N2 - Recent studies have confirmed the widening of the weld pool interface, known as a bulge effect, during deep penetration high power laser beam welding. The link between such geometric particularities of the weld pool shape and the hot cracking phenomena is significant. The present work seeks to extend the level of understanding by investigating their relationship. A coupled multiphysics, multiscale numerical framework is developed, comprising a series of subsequent analyses. The study examines the influences of the bulge on the three most dominant effects causing hot cracking, namely the thermal cycles, the mechanical loading, and the local microstructure. The bulge in the weld pool shape forms approximately in the middle of the plate, thus correlating with the location of hot cracking. It increases the hot cracking susceptibility by enhancing the three dominant effects. The numerical results are backed up by experimental data. T2 - 11th CIRP Conference on Photonic Technologies [LANE 2020] KW - Hot cracking KW - Bulge effect KW - Numerical modelling KW - Laser beam welding KW - Deep penetration PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-512783 DO - https://doi.org/10.1016/j.procir.2020.09.002 SN - 2212-8271 VL - 94 SP - 5 EP - 10 PB - Elsevier B.V. CY - Amsterdam [u.a.] AN - OPUS4-51278 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Artinov, Antoni A1 - Bakir, Nasim A1 - Bachmann, Marcel A1 - Gumenyuk, Andrey A1 - Na, S.-J. A1 - Rethmeier, Michael T1 - On the search for the origin of the bulge effect in high power laser beam welding N2 - The shape of the weld pool in laser beam welding plays a major role to understand the dynamics of the melt and its solidification behavior. The aim of the present work was its experimental and numerical investigation. To visualize the geometry of the melt pool in the longitudinal section a butt joint configuration of 15 mm thick structural steel and transparent quartz glass was used. The weld pool shape was recorded by means of a high-speed video camera and two thermal imaging MWIR and VIS cameras. The observations show that the dimensions of the weld pool vary depending on the depth. The regions close to the surface form a teardrop shaped weld pool. A bulge-region and its temporal evolution were observed approximately in the middle of the depth of the weld pool. Additionally, a transient numerical simulation was performed until reaching a steady state to obtain the weld pool shape and to understand the formation mechanism of the observed bulging phenomena. A fixed keyhole with an experimentally obtained shape was used to represent the full-penetration laser beam welding process. The model considers the local temperature field, the effects of phase transition, thermo-capillary convection, natural convection and temperature-dependent material properties up to evaporation temperature. It was found that the Marangoni convection and the movement of the laser heat source are the dominant factors for the formation of the bulging-region. Good correlation between the numerically calculated and the experimentally observed weld bead shapes and the time-temperature curves on the upper and bottom surface were found. T2 - International Congress on Applications of Lasers & Electro-Optics (ICALEO®) CY - Orlando, USA DA - 14.10.2018 KW - Bulging effect KW - High power laser beam welding KW - Numerical modelling KW - Solidification cracking PY - 2019 SP - 1 EP - 8 AN - OPUS4-47139 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Fabry, Çağtay A1 - Hirthammer, Volker A1 - Rethmeier, Michael T1 - Open Science in der Schweißtechnik N2 - Darstellung der aktuellen Situation sowie des Potenzials von Forschungsdatenmanagement und OpenScience in der Schweißtechnik. T2 - WelDX - Open Science Seminar CY - BAM Berlin, Germany DA - 04.03.2020 KW - Digitalisierung KW - Schweißtechnik KW - OpenScience KW - Forschungsdatenmanagement PY - 2020 UR - https://www.bam.de/Content/DE/Veranstaltungen/2020/2020-03-09-weldx-open-science-seminar.html AN - OPUS4-51857 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Rethmeier, Michael A1 - Schwenk, Christopher A1 - Heinze, Christoph T1 - Optimierung von Verzug und Eigenspannungen beim Schweißen dickwandiger Bauteile N2 - Die Schweißsimulation dickwandiger Bauteile stellt aufgrund der erhöhten Komplexität der thermophysikalischen und thermomechanischen Vorgänge beim Mehrlagenschweißen hohe Anforderungen an kommerziell verfügbare Schweißsimulationssoftware. Das umfasst die während des Fügeprozesses induzierten Verzüge und Eigenspannungen in das gefertigte Bauteil, welche zur Beurteilung der Fertigungsqualität von großer Bedeutung sind. Gerade in dickwandigen Bauteilen ist der Spannungszustand sowohl bedingt durch die konstruktive Steifigkeit der einzelnen Bauteile sowie der gesamten Baugruppe als auch aufgrund zusätzlicher externer Einspannvorrichtungen bei der Fertigung überaus komplex. Hinzu kommen bei Werkstoffen mit Phasenumwandlung noch die metallurgisch verursachten Spannungszustände und bei mehrlagig ausgeführten Schweißverbindungen die wiederholte thermische und umwandlungsbedingte Spannungsausbildung, so dass eine überschlägige Abschätzung des gesamten Verformungs- und Spannungszustandes auch für Experten in der Regel nicht mehr möglich ist. Die vorherrschenden Verformungen und Spannungen bestimmen jedoch maßgeblich die Eigenbeanspruchung der Schweißkonstruktion und damit deren Belastbarkeit im Betrieb. Eine genaue Kenntnis dieser Daten würde wertvolle Informationen zur Qualitätsoptimierung des Endproduktes liefern. KW - Schweißsimulation KW - Eigenspannungen KW - Verzug KW - Validierung KW - Sysweld KW - Mehrlagenschweißen PY - 2011 SN - 3-937567-98-4 SP - 1 EP - 160 PB - Verlag und Vertriebsgesellschaft mbH CY - Düsseldorf AN - OPUS4-23350 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gook, S. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Orbital hybrid laser-arc welding using a high-power fibre laser for pipeline construction N2 - Recently developed fibre lasers provide multi-kilowatt beam power with high quality at impressive energy efficiency. Combined with gas metal arc welding (GMAW) equipment these lasers can be used in a hybrid process to weld thick-walled constructions single-pass, that are currently welded using multi-pass techniques. The main benefits are a reduction of heat induced distortions, due to the low heat input, as well as savings in filler material and process time. Probable applications can be found in power generation, ship building and pipeline constructions. An orbital (girth) laser-hybrid process using a 20 kW fibre laser and a GMAW torch is currently examined at the BAM, Berlin. The aim of this research is to obtain a stable and crack free girth welding process and to demonstrate its application in pipeline construction. The experiments are carried out on 16 mm thick plates as well pipe rings with 36" (914 mm) pipe diameter of X65. Particular welding parameters, such as welding speed, GMAW power, arc length are varied and their influence on the appearance of the weld in the different welding positions is analyzed. Even though issues remain that demand further research it could already be shown that the rings can be welded using a girth hybrid process that is divided into two half girth processes in downward direction. KW - High-power fibre laser KW - Thick plates KW - Laser-hybrid welding KW - Pipeline PY - 2018 UR - http://gns.mephi.ru/en/issues/2018-126?art=418 SN - 2499-9733 SN - 2305-414X VL - 1 IS - 26 SP - 47 EP - 57 PB - National Research Nuclear University "MEPhI" CY - Volgodonsk AN - OPUS4-45046 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Gook, Sergej A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael ED - Ostendorf, A. ED - T. Graf, ED - D. Petring, ED - Otto, A. T1 - Orbital laser-hybrid welding of pipelines using a 20 kW fibre laser T2 - 5th International WLT-Conference on Lasers in Manufactoring CY - Munich, Germany DA - 2009-06-15 KW - High power fibre laser KW - Laser-hybrid welding KW - Pipeline KW - Thick plates KW - Orbital process PY - 2009 SN - 978-3-00-027994-2 SP - 65 EP - 70 PB - AT-Fachverl. CY - Stuttgart AN - OPUS4-19593 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gumenyuk, Andrey A1 - Gook, Sergej A1 - Rethmeier, Michael A1 - Kohn, H. T1 - Orbitalschweißen im Pipelinebau - Neue Möglichkeiten durch die Anwendung von Hochleistungslasern T2 - 8. Internationale Konferenz Strahltechnik CY - Halle/Saale, Deutschland DA - 2010-04-14 KW - Laser-MSG-Hybrid Schweißen KW - Orbitalschweißen KW - Hochleistungslaser PY - 2010 SP - 74 EP - 79 CY - Halle (Saale) AN - OPUS4-21225 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Frei, J. A1 - Rethmeier, Michael T1 - Overview and new developments in research on resistance spot welding of advanced high strength steels N2 - The safe joining of new, freshly developed steel types keeps challenging the industry–and is assumed to go on in doing so. In the body-in-white production, these materials are mainly joined using resistance spot welding. During the past ten years, various investigations on resistance spot welding of advanced high strength steels have been carried out at Fraunhofer IPK and the Federal Institute for Materials Research and Testing (BAM). This paper aims to give an overview about both the top former and recent studies and results. The investigated topics are the influences of manufacturing conditions as initial gaps and restraints on spot welds, their impact on the fatigue strength of a joint and the cracking-wise safe weldability of AHSS. Caused by non-ideal manufacturing conditions, cracks in spot welds (e.g. caused by liquid metal embrittlement) are still regarded as a potential risk in industrial practice. Therefore, a method to evaluate the safe weldability regarding the cracking susceptibility was developed for AHSS. The method is easy to perform, even without expensive laboratory equipment. It allows the end user to establish a material ranking regarding the cracking susceptibility of the handled steels. Recently, coupled thermo-mechanical finite element modelling has been used to describe critical stress-strain conditions responsible for the occurrence of liquid metal embrittlement, and to improve the understanding of the process. T2 - The 5th International Conference on Steels in Cars and Trucks CY - Amsterdam-Schiphol, The Netherlands DA - 19.06.2017 KW - Advanced high strength steels KW - Resistance spot welding KW - Cracking susceptibility KW - Liquid metal embrittlement KW - Material ranking KW - Fatigue strength KW - Gaps KW - Finite element method PY - 2017 SP - 1 EP - 8 AN - OPUS4-43189 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gook, Sergej A1 - Gumenyuk, Andrey A1 - Lammers, Marco A1 - Rethmeier, Michael T1 - Peculiarities of the process of orbital laser-arc welding of thick-walled large-diameter pipes KW - Hybrid laser-arc welding KW - Orbital welding KW - High-pressure pipelines KW - Fibre-optic lasers PY - 2010 SN - 0957-798X VL - 9 SP - 2 EP - 8 PB - E. O. Paton Electric Welding Institute of the National Acad. of Sciences of Ukraine CY - Kyïv AN - OPUS4-22956 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gook, Sergej A1 - Gumenyuk, Andrey A1 - Lammers, Marco A1 - Rethmeier, Michael T1 - Peculiarities of the process of orbital laser-arc welding of thick-walled large-diameter pipes KW - Hybrid laser-arc welding KW - Orbital welding KW - High-pressure pipelines KW - Fibre-optic lasers PY - 2010 SN - 0005-111x SN - 0005-2302 VL - 689 IS - 9 SP - 5 EP - 13 CY - Kiev, Ukraine AN - OPUS4-22979 LA - rus AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael A1 - Gook, Sergej A1 - Gumenyuk, Andrey T1 - Perspectives of application of laser-GMA-hybrid girth welding for pipeline construction T2 - VI. International conference "Beam technologies & laser application" CY - Saint Petersburg, Russia DA - 2009-09-23 KW - Fibre laser KW - Laser-hybrid welding PY - 2009 SP - 1 EP - 15(?) CY - Saint Petersburg, Russia AN - OPUS4-20766 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael A1 - Gook, Sergej A1 - Gumenyuk, Andrey T1 - Perspectives of application of laser-GMA-hybrid girth welding for pipeline construction T2 - The Vi International Conference "Beam Technologies & Laser Application", State Polytechnical University CY - Saint Petersburg, Russia DA - 2009-09-23 PY - 2009 AN - OPUS4-20408 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rethmeier, Michael A1 - Brauser, Stephan A1 - Weber, Gert T1 - Potential of optical strain field measurement for the characterisation of the properties of resistance-spot-welded joints N2 - For the designing of safety-relevant components particularly by means of finite element calculations, great significance is attached to the determination of local material parameters in the welding region. Conventional test methods can merely provide global parameters which, however, are frequently not sufficient precisely for the calculation of resistance-spot-welded components since these are characterised by the existence of joining zones with tight local limitations. In contrast, modern test methods such as optical strain field measurement permit the determination of the characteristic material data for concrete locations and times. In order to establish the potential of optical strain field measurements for the characterisation of the local material behaviour of spotwelded joints, tensile shear tests as well as tensile tests were carried out on resistance-spot-welded high-strength steels. The results show the high potential of this procedure not only for the quantification of the local strain behaviour in the joining region but also for the determination of local characteristic material data. PY - 2011 SN - 1612-3433 VL - 10 IS - 1 SP - 48 EP - 52 PB - DVS - German Welding Society CY - Düsseldorf AN - OPUS4-23220 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brauser, Stephan A1 - Weber, Gert A1 - Rethmeier, Michael T1 - Potenzial optischer Dehnungsfeldmessung zur Charakterisierung der Eigenschaften von Widerstandspunktschweißverbindungen N2 - Die Ermittlung lokaler Werkstoffkennwerte im Schweißbereich ist für die Auslegung sicherheitsrelevanter Bauteile insbesondere durch Finite-Elemente-Berechnungen von großer Bedeutung. Konventionelle Prüfmethoden können lediglich globale Kennwerte bereitstellen, die jedoch gerade für die Berechnung widerstandspunktgeschweißter Bauteile häufig nicht ausreichen, da diese durch das Vorliegen örtlich eng begrenzter Fügezonen gekennzeichnet sind. Moderne Prüfmethoden wie die optische Dehnungsfeldmessung ermöglichen hingegen eine orts- und zeitkonkrete Bestimmung der Werkstoffkenndaten. Um das Potenzial optischer Dehnungsfeldmessungen für das Charakterisieren des lokalen Werkstoffverhaltens von Punktschweißverbindungen zu ermitteln, wurden Scherzugversuche sowie Zugversuche an widerstandspunktgeschweißten hochfesten Stählen durchgeführt. Die Ergebnisse zeigen das hohe Potenzial dieses Verfahrens sowohl für die Quantifizierung des lokalen Dehnungsverhaltens im Fügebereich als auch für die Ermittlung lokaler Werkstoffkenndaten. PY - 2010 SN - 0036-7184 VL - 62 IS - 9 SP - 496 EP - 500 PB - Verl. für Schweißen u. Verwandte Verfahren, DVS-Verl. CY - Düsseldorf AN - OPUS4-22163 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chen, Ji A1 - Schwenk, Christopher A1 - Wu, Chuan Song A1 - Rethmeier, Michael T1 - Prediction of weld pool shape and influence of joint preparation angle for new gas metal arc welding processes N2 - This article studies the three dimensional transient weld pool dynamics and the influence of joint preparation angle on welding of low carbon structural steel plates using the ForceArc® process. ForceArc is a new gas metal arc welding technology which allows adequate fusion and penetration with a smaller V groove angle. This enhances welding efficiency significantly because of reduction of layers and low material consumption. The deformation of the weld bead is calculated with an accurate coupling of the heat transfer with fluid flow through continuity, momentum and the energy equations combined with the effect of droplet impingement, gravity, electromagnetic force, buoyancy, drag forces and surface tension force (Marangoni effect). Four different angles of V groove are employed with the same welding parameters and their influence on the weld pool behavior and weld bead geometry is calculated and analyzed, to allow subsequent calculations of residual stress and distortion of the workpiece. Such a simulation is an effective way to study welding processes because the influence of all the welding parameters can be analyzed separately with respect to thermal cycle, weld bead formation, and the microstructure of the weld. Good agreement is shown between the predicted and experimentally determined weld bead dimensions. It was found that with a larger groove angle, the penetration depth increases. Furthermore, a higher wire feeding rate is needed to fill the larger groove. The model presented can be used for further analyses of GMAW processes as well as input data for the numerical calculation of welding induced residual stresses and distortions using Computational Weld Mechanics CWM. T2 - JOM-16 - 16th International Conference on the Joining of Materials CY - Tisvildeleje, Denmark DA - 10.05.2011 KW - Numerical simulation KW - Gas metal arc welding KW - Weld pool shape KW - Fluid flow KW - V groove PY - 2011 SN - 87-89582-19-5 IS - JOM 7 / J15 SP - 1 EP - 13 AN - OPUS4-23984 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Straße, Anne A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael ED - Schmidt, M. ED - Vollertsen, F. ED - Schmidt, B. M. T1 - Preliminary study to investigate the applicability of optical strain measurement technique for the detection of hot cracks in laser metal deposited layers N2 - Laser metal deposition (LMD) as an additive manufacturing technique became increasingly important in recent years and thus the demand for component safety. This is the reason, for the need for reliable in-situ defect detection techniques. For laser beam weld seams an optical measurement technique based on an optical flow algorithm was successfully used to define the critical straining conditions that lead to hot cracking. This algorithm was adapted for bead-on-plate weld seams on LMD deposited layers of IN718 alloy while performing external strain on the specimen in an externally loaded hot cacking test facility. The resulting transversal hot cracks along the weld seam were localized via X-Ray inspection and the type of cracking confirmed by Scanning Electron Microscopy (SEM). The strain distribution was measured in the vicinity of the solidification front and correlated to the detected hot cracks. Based on the results this technique could be adopted for LMD experiments. T2 - 12th CIRP Conference on Photonic Technologies [LANE 2022] CY - Fürth, Germany DA - 04.09.2022 KW - Laser Metal Deposition (LMD) KW - Strain measurement KW - Optical flow KW - Critical strain PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-556445 DO - https://doi.org/10.1016/j.procir.2022.08.034 VL - 111 SP - 335 EP - 339 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-55644 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Marko, A. A1 - Bähring, S. A1 - Raute, J. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Prognose von Qualitätsmerkmalen durch Anwendung von KI-Methoden beim Directed 10 Energy Deposition N2 - Dieser Beitrag enthält die Ergebnisse eines im Rahmen der DVS Forschung entwickelten Ansatzes zur Qualitätssicherung im Directed Energy Deposition. Es basiert auf der Verarbeitung verschiedener während des Prozesses gesammelter Sensordaten unter Anwendung Künstlicher Neuronale Netze (KNN). So ließen sich die Qualitätsmerkmale Härte und Dichte auf der Datenbasis von 50 additiv gefertigten Probenwürfel mit einer Abweichung < 2 % vorhersagen. Des Weiteren wurde die Übertragbarkeit des KNN auf eine Schaufelgeometrie untersucht. Auch hier ließen sich Härte und Dichte hervorragend prognostizieren (Abweichung < 1,5 %), sodass der Ansatz als validiert betrachtet werden kann. KW - Kl KW - Directed Energy Depositio KW - Qualitätssicherung PY - 2022 SN - 0036-7184 VL - 74 IS - 10 SP - 672 EP - 679 PB - DVS Media CY - Düsseldorf AN - OPUS4-56284 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael A1 - Gook, Sergej A1 - Gumenyuk, Andrey ED - Turichin, G. T1 - Prospects of application of laser-GMA hybrid welding for manufacturing of large diameter longitudinal welded high strength steel pipes T2 - VII. International scientific and technical conference 'Beam technologies & laser application' CY - Saint-Petersburg, Russia DA - 2012-09-18 KW - High strength steel KW - Laser hybrid welding KW - Modified spray arc KW - Longitudinal weld KW - Pipeline PY - 2013 SP - 130 EP - 140 PB - Publishing house SPbSPU AN - OPUS4-28040 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Rethmeier, Michael A1 - Biegler, M. A1 - Javaheri, E. T1 - Qualifizierung der instrumentierten Eindringprüfung zur Kennwertermittlung für hochfeste Stähle mit Schweißungen N2 - Der Einsatz von hochfesten Stählen im Karosseriebereich des Automobilbaus hat während der letzten Jahre stark zugenommen. Hierzu zählen Dual- und Komplexphasenstähle, welche durch Kombination unterschiedlicher Gefügebestandteile auch deren Vorteile kombinieren, sowie TRIP (TRansformation Induced Plasticity) und Mangan-Bor Stähle, welche sehr gute Umformeigenschaften mit hohen Festigkeiten durch Martensitbildung bei der Umformung kombinieren. TWIP (Twinning Induced Plasticity) Stähle erreichen ähnliche Effekte durch forcierte Zwillingsbildung. Die Ursachen für den Einsatz dieser Stähle liegen in dem Potential dieser Materialien zur Gewichts- und Kostenreduzierung, bei gleichzeitiger Erhöhung der Fahrgastsicherheit. Auf Grund der prinzipiell gegebenen Schweißeignung dieser Stähle, werden die klassischen Fügeverfahren im Karosseriebau wie das kostengünstige und effektive Widerstandspunktschweißen, das Metall-Schutzgas (MSG)-Schweißen oder das Laserschweißen angewendet. Allerdings treten teilweise Herausforderungen, beispielsweise durch Gefügeveränderungen in den Fügestellen auf, die zu ungewollten Aufhärtungen oder Erweichungen führen. In diesem Projekt wird ein Verfahren entwickelt, mit welchem die lokalen Werkstoffeigenschaften von im Automobilbau typischen Werkstoffen und deren Fügestellen bestimmt werden können. Relevante Kennwerte sind in erster Linie das SpannungsDehnungs-Verhalten der verschiedenen Zonen einer Schweißverbindung; relevante Zonen wiederum sind neben dem Grundwerkstoff die Wärmeeinflusszone und das Schweißgut. Zu diesem Zweck wird das Verfahren der instrumentierten Eindringprüfung für den Einsatz bei hochfesten Stählen weiterentwickelt. Zunächst werden hierzu Zugversuche an einfachen Grundwerkstoffgeometrien durchgeführt. Im Anschluss wird die optische Dehnungsfeldmessung an stark taillierten, geschweißten Zugversuchsproben durchgeführt. Die Taillierung dient dem Zweck, die WEZ auch mittels WPS über den gesamten Querschnitt der Probe erzeugen zu können, bzw. im Versuch auch Dehnungen in den relevanten Bereichen herbeizuführen. Das im Projekt angewendete Auswerteverfahren, welches auf nichtlinearen Regressionsmodellen in Form von künstlichen, neuronalen Netzwerken beruht, ermöglicht die Vorhersage des Festigkeitsverhaltens des Werkstoffes anhand der gemessenen Krafteindringwegdaten. KW - Eindringprüfung KW - Hochfester Stahl KW - Prüfverfahren PY - 2020 SN - 978-3-946885-98-6 SP - 1 EP - 164 PB - Forschungsvereinigung Stahlanwendungen AN - OPUS4-57322 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Rethmeier, Michael A1 - Biegler, M. T1 - Qualifizierung der Schweißstruktursimulation für die wirtschaftliche Bearbeitung additiver fertigungstechnischer Fragestellungen am Beispiel des Laserpulverauftragschweißens N2 - Additive Fertigungsverfahren, speziell das selektive Laserschmelzen sowie das Laserpulverauftragsschweißen, ermöglichen eine enorme Steigerung der Flexibilität und erlauben Kleinserienteile mit hoher Genauigkeit und geringen Kosten herzustellen. Für den erfolgreichen wirtschaftlichen Einsatz dieser neuartigen Fertigungsverfahren spielt die Einhaltung des First-time-right-Prinzips eine entscheidende Rolle: Bauteile sollten bereits im ersten Versuch allen Anforderungen genügen. Aufgrund der jungen Geschichte dieses Fertigungszweigs und der damit einhergehenden fehlenden Erfahrungen und Richtlinien ist diese elementare Forderung heute nur in wenigen Fällen realisierbar. Die geforderten Qualitätsstandards können aktuell nur über experimentelle Iterationsschleifen eingehalten werden, sodass das große Potential einer flexiblen und schnellen Fertigung in erheblichem Maß reduziert wird. Die Komplexität der gefertigten Bauteile und die des Prozesses an sich lassen eine erfahrungsbasierte Vorhersage der Verzüge und Eigenspannungen kaum zu. Zudem werden auch in Zukunft Richtlinien und Normen nicht das komplette Anwendungsspektrum abbilden können. Die eigenspannungsbedingten Verzüge spielen demnach eine bedeutende Rolle und stellen zusammen mit dem Erreichen der Maßhaltigkeit eine entscheidende technologische Herausforderung beim Einsatz additiver Fertigungsverfahren dar. Die numerische Simulation ermöglicht die Vorhersage von Bauteilverzügen und –spannungen und kann durch virtuelle Abprüfung von Herstellstrategien die Anzahl von Experimente reduzieren. Bisherige numerische Betrachtungen von zusatzwerkstoffbasierten Verfahren, zu denen unter anderem das Laserpulverauftragschweißen (LPA) gehört, beschränkten sich primär auf akademische Beispiele mit geringer Komplexität. Für die Simulation von konkreten Anwendungsfällen auf Bauteilebene liegen bisher keine validierten, numerischen Methoden und Ansätze vor, die eine wirtschaftliche Anwendung der Schweißsimulation ermöglichen. Dieses Projekt wird Simulationsmodelle zur numerischen Betrachtung komplexer additiv gefertigter Bauteile entwickeln. Dafür wird der Prozess in vereinfachten Simulationen nachgebildet und anhand von Experimenten validiert. Anschließend werden Methoden zur automatisierten Pfadgenerierung für komplexe Bauteile erprobt und in der Simulation implementiert. Schließlich werden zur Reduktion der Rechenzeit verschiedene Methoden zur Vereinfachung evaluiert und verglichen. Das Ziel ist die Steigerung der Verlässlichkeit in der Simulation, um prädiktive Aussagen über die Qualität additiv gefertigter Bauteile zu ermöglichen. KW - Schweißstruktursimulation KW - LPA KW - Additive Manufacturing PY - 2019 SN - 978-3-96780-042-5 SP - 1 EP - 106 PB - Forschungsvereinigung Stahlanwendungen AN - OPUS4-57321 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Quality improvement of laser welds on thick duplex plates by laser cladded buttering N2 - Because of its excellent corrosion resistance, high tensile strength and high ductility, duplex stainless steel 2205 offers many areas of application. Though laser beam welding accompanied by high cooling rates, duplex steels tend to perform higher ferrite contents in weld metal as the base metal, which leads to a reduction of ductility and corrosion resistance of the weld joint. To overcome this problem, a solution, based on buttering the plate edges by laser metal deposition (LMD) with material containing higher Ni concentrations prior to laser welding was suggested. In this context different process parameters for LMD process were investigated. In a second step the possibility of welding those edges defect free while achieving balanced austenite-ferrite ratio was verified with metallographic analysis, Electron Backscatter Diffraction (EBSD) and impact testing according to Charpy. T2 - Lasers in Manufacturing (LiM) 2019 CY - Munich, Germany DA - 24.06.2019 KW - Laser Metal Deposition; Laser Beam Welding; Duplex; Stainless Steel PY - 2020 SP - We_A31_4_4-1 EP - We_A31_4_4-6 PB - WLT (Wissenschaftliche Gesellschaft für Lasertechnik) AN - OPUS4-50143 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Marko, A. A1 - Bähring, S. A1 - Raute, J. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Quality Prediction in Directed Energy Deposition Using Artificial Neural Networks Based on Process Signals N2 - The Directed Energy Deposition process is used in a wide range of applications including the repair, coating or modification of existing structures and the additive manufacturing of individual parts. As the process is frequently applied in the aerospace industry, the requirements for quality assurance are extremely high. Therefore, more and more sensor systems are being implemented for process monitoring. To evaluate the generated data, suitable methods must be developed. A solution, in this context, was the application of artificial neural networks (ANNs). This article demonstrates how measurement data can be used as input data for ANNs. The measurement data were generated using a pyrometer, an emission spectrometer, a camera (Charge-Coupled Device) and a laser scanner. First, a concept for the extraction of relevant features from dynamic measurement data series was presented. The developed method was then applied to generate a data set for the quality prediction of various geometries, including weld beads, coatings and cubes. The results were compared to ANNs trained with process parameters such as laser power, scan speed and powder mass flow. It was shown that the use of measurement data provides additional value. Neural networks trained with measurement data achieve significantly higher prediction accuracy, especially for more complex geometries. KW - DED KW - Artificial neural network KW - Data preparation KW - Quality assurance KW - Process monitoring PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-555063 DO - https://doi.org/10.3390/app12083955 SN - 2076-3417 VL - 12 IS - 8 SP - 1 EP - 13 PB - MDPI CY - Basel AN - OPUS4-55506 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Schaumann, P. A1 - Schürmann, K. A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Quantifizierung der Einflüsse aus Fertigungsautomatisierung und Innenschweißen auf die Ermüdungsfestigkeit von Hohlprofilknoten für Offshore-Windenergieanlagen T1 - Quantifying the effects of manufacturing automation and internal welding on the fatigue resistance of circular hollow section joints for offshore wind energy converters N2 - Die Entwicklung in der Offshore-Windenergie hin zu größeren, leistungsstärkeren An-lagentypen sowie die zeitgleich zunehmenden Wassertiefen der projektierten Wind-parks stellt u. a. Designer und Fertiger der Gründungsstrukturen von Windenergiean-lagen vor wachsende Herausforderungen. Neben dem Gründungskonzept der XL-Monopiles rückt wegen der Kombination aus dem vergleichsweise geringen Materialverbrauch bei gleichzeitig hoher Steifigkeit, auch die Jacketgründung in den Fokus. Der Fertigungsaufwand der Jackets ist verglichen mit Monopiles groß; kann jedoch durch die Nutzung von Standardrohren mit automatisiert gefertigten Jacketknoten reduziert werden. Vor diesem Hintergrund beschreibt der vorliegende Forschungsbericht den Fertigungs-prozess zum automatisierten Schweißen von X-förmigen Hohlprofilknoten für Jacket-Gründungsstrukturen von Offshore-Windenergieanlagen. Ein weiteres wesentliches Ziel dieses Vorhabens war die konsequente Digitalisierung der schweißtechnischen Fertigungskette während der automatisierten Schweißung der X-Knoten. Die so ge-speicherten Prozessparameter können zum einen als Grundlage einer Qualitätskon-trolle dienen, zum anderen ermöglichen sie eine vollständige Nachverfolgbarkeit der automatisiert gefertigten Rohrknoten. Der zweite maßgebend in diesem Bericht behandelte Aspekt umfasst die Quantifizie-rung der Einflüsse aus Fertigungsautomatisierung und Innenschweißen auf die Ermü-dungsfestigkeit der Hohlprofilknoten auf Basis serieller Ermüdungsversuche. Dazu wurden im Projekt zwei Serien mit jeweils 16 Schwingversuchen an ein- und doppel-seitig automatisiert geschweißten X-Knoten durchgeführt und entsprechende Struktur-spannungswöhlerlinien für die automatisiert gefertigten X-Knoten bestimmt. Die Ergebnisse dieser Ermüdungsversuche werden abschließend in numerischen Untersuchungen auf Basis der Strukturspannungs- und des Kerbspannungskonzeptes gegenübergestellt, um die Prognosefähigkeit beider Konzepte für die ermüdungs-kritischen Bereiche des X-Knotens bewerten zu können. Durch die im Forschungsvorhaben durchgeführten schweißtechnischen, experimen-tellen und numerischen Analysen konnte das Potential automatisiert gefertigter Rohr-knoten hinsichtlich Reproduzierbarkeit und Ermüdungsverhalten quantifiziert werden. Zusätzlich konnte der Einfluss der inneren Schweißnaht auf die Ermüdungsfestigkeit bewertet werden. N2 - The development within the offshore wind sector towards more powerful turbines combined with increasing water depth for new wind parks is challenging both the designer as well as the manufacturer of bottom fixed support structures. Besides XL-monopiles, the market developed an innovative and economic jacket support structure, which is based on automatically manufactured tubular joints combined with standardized pipes. Besides the improvements for a serial manufacturing process the automatically welded tubular joints show a great potential in terms of fatigue resistance e.g. due to a smooth weld geometry without sharp notches. However, these benefits are not considered yet within the fatigue design process of automatically manufactured jacket substructures according to standards and guidelines due to the lack of suitable S-N curves. Therefore, within this research project the automatically welding process of tubular joints for jacket support structures of offshore wind energy turbines was developed. Additionally, the project was focused on a consistent digitalization of the welding production chain during the automated welding of the X-joints. These stored process parameters can then serve as the basis for quality checks and a complete traceability of the automatically produced tubular joints is enabled. The second aspect dealt within this report is the quantification of the effects of production automation and internal welding on the fatigue resistance of the tubular joints by performing serial fatigue tests. For this purpose, two series each with 16 fatigue tests on single- and double-sided automatically welded X-joints were carried out in the project to determine structural stress based S-N curves for the automatically welded X-joints. The results of these fatigue tests are then compared to numerical investigations based on the structural stress as well as notch stress approach. The outcomes are then compared to evaluate the capability of both approaches for the prediction of the fatigue-critical locations within the X-joints. Based on the analysis of the welding procedure as well as the experimental and numerical investigations within this research project, the potential of automatically manufactured tubular joints with regard to reproducibility and fatigue behaviour was investigated. In addition, the effects of an inner root layer on the fatigue resistance was evaluated. KW - Lightweight Design KW - Jacket Support Structures KW - Fatigue KW - Arc Welding Automation KW - Offshore Wind PY - 2020 UR - https://shop.stahldaten.de/produkt/p-1178-quantifizierung-der-einfluesse-aus-fertigungsautomatisierung-und-innenschweissen-auf-die-ermuedungsfestigkeit-von-hohlprofilknoten-fuer-offshore-windenergieanlagen SN - 978-3-946885-79-5 VL - Bericht P1178 SP - 1 EP - 189 AN - OPUS4-51855 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schwenk, Christopher A1 - Rethmeier, Michael A1 - Weiss, D. ED - H.K.D.H. Bhadeshia, ED - H. Cerjak, ED - E. Kozeschnik, T1 - Rapid generation of temperature fields for simulation of welding distortions PY - 2007 SN - 978-3-902465-69-6 SP - 835 EP - 846 CY - Graz, Austria AN - OPUS4-16491 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Häberle, Nicolas A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Rechenzeitersparnis bei der numerischen Lösung der nicht- linearen transienten 3D-Wärmeleitungsgleichung durch explizite Zeitintegration N2 - Die transiente nichtlineare 3D-Wärmeleitungsgleichung wurde zur numerischen Lösung mittels der Finite-Elemente-Methode im Ort und mittels explizitem Eulerschema in der Zeit diskretisiert. Der resultierende Algorithmus wurde in ein Computerprogramm überführt wobei besonderer Wert auf paralleles Rechnen gelegt wurde. Das Programm wurde auf die numerische Berechnung eines schweißtypischen transienten Temperaturfelds angewandt. Die Rechenzeit und Skalierbarkeit des Computerprogramms bezüglich der Anzahl verwendeter CPU Kerne wurde untersucht und mit dem kommerziellen FEM Programm Abaqus 6.14 verglichen. Die Anwendung der expliziten Zeitintegration resultiert in verbesserter Skalierbarkeit bezüglich der Anzahl verwendeter CPU Kerne und Rechenzeitersparnis gegenüber der in Abaqus implementierten impliziten Zeitintegrationsmethode. T2 - 37. Assistentenseminar Füge- und Schweißtechnik CY - Päwesin, Germany DA - 5. September 2016 KW - Schweißsimulation PY - 2017 SN - 978-3-96144-025-2 VL - 339 SP - 115 EP - 120 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-44282 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reisgen, U. A1 - Olschok, S. A1 - Backhaus, A. A1 - Rethmeier, Michael A1 - Gumenyuk, Andrey A1 - Tölle, Florian T1 - Reduction of weld residual stresses with the electron beam T2 - 2nd International electron beam welding conference (IEBW) CY - Aachen, Germany DA - 2012-03-26 PY - 2012 SN - 978-3-87155-299-1 N1 - Serientitel: DVS-Berichte – Series title: DVS-Berichte VL - 285 SP - 128 EP - 132 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-26110 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tölle, Florian A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael ED - Halmoy, E. T1 - Residual stress reduction by beam defocusing in beam welding processes N2 - Residual stresses arising during welding, especially in high energy beam welding, can reach levels up to the material specific yield strength causing service life mitigating consequences through stress relaxation or stress corrosion cracking. A number of processes were developed like stress relief annealing or the low-stress-no-distortion-technique to reduce these stresses. But such methods are only applicable for wider welds and simple component geometries or they are cost-intensive. The method presented in this paper uses the welding beam after welding in a defocused mode for heating the material regions in a certain distance from the weld on both sides. With this process it is possible to decrease the stresses in small welds with high stress gradients without any contact surfaces or additional equipment. Dependent on the component geometry and on the laser power it is possible to use different parameters for this process. The adjustable process parameters are the radius and the power of the defocused beam and the transversal and longitudinal distances between the welding and the defocused beam. In this work the mechanism and the influence of the process parameters are investigated by FEM-simulation and a number of experiments on the ferritic steel S355J2+N with 5 mm thickness. The best experimental result presented in this paper shows a stress reduction of about 73 %. T2 - 13th NOLAMP conference - 13th Conference on laser materials processing in the nordic countries CY - Trondheim, Norway DA - 27.06.2011 KW - Residual stresses KW - Stress reduction KW - High energy beam welding KW - Post-weld heat treatment KW - Laser scanner optics PY - 2011 SN - 978-82-998664-1-5 SP - 235 EP - 245 AN - OPUS4-24274 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kannengießer, Thomas A1 - Kromm, Arne A1 - Rethmeier, Michael A1 - Gibmeier, J. A1 - Genzel, C. T1 - Residual stresses and in-situ measurement of phase transformation in low transformation temperature (LTT) welding materials PY - 2009 SN - 1097-0002 SN - 0069-8490 SN - 0376-0308 VL - 52 SP - 755 EP - 762 CY - Newtown Square, Pa., USA AN - OPUS4-19817 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Frei, J. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Resistance spot welding under external load for evaluation of LME susceptibility of zinc coated advanced high strength steel sheets N2 - Some zinc coated advanced high strength steels (AHSS), under certain manufacturing conditions, are known to be prone to liquid metal embrittlement (LME) during resistance spot welding. LME is an undesired phenomenon, which can cause both surface and internal cracks in a spot weld, potentially influencing its strength. An effort is made to understand influencing factors of LME better, and evaluate geometry-material combinations regarding their LME susceptibility. Manufacturers benefit from such knowledge because it improves the processing security of the materials. The experimental procedure of welding under external load is performed with samples of multiple AHSS classes with strengths up to 1200 MPa, including dual phase, complex phase and TRIP steels. This way, externally applied tensile load values are determined, which cause liquid metal embrittlement in the samples to occur. In the future, finite element simulation of this procedure gives access to in-situ stress and strain values present during LME formation. The visualization improves the process understanding, while a quantification of local stresses and strains allows an assessment of specific welded geometries. T2 - ESDAD 2019 CY - Dusseldorf, Germany DA - 24.06.2019 KW - RSW KW - LME KW - Advanced high strength steel KW - Testing method KW - Zinc coated steel PY - 2019 AN - OPUS4-49079 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schwenk, C. A1 - Kannengießer, Thomas A1 - Rethmeier, Michael T1 - Restraint conditions and welding resiudal stresses in self-restrained cold cracking test N2 - In the last decade, high-strength fine grained steels and welding consumables have gained a strong raise of application ranging from mobile cranes to bridge constructions. However, the cracking susceptibility of these steels increases significantly in correspondence with the achieved improvements in yield strength and the loss in plastic deformation reserves. In order to determine this behavior a series of different standardized cold cracking tests has been developed. One remaining major problem of these tests is the uncertainty about the quantitative intensity of the restraint conditions as well as the corresponding welding residual stresses. Consequently, the comparison of different tests and welding conditions as well as the transferability of the results onto real parts is difficult at best. The main topic of this paper is the analysis of the restraint conditions and their link with the welding induced residual stresses. The importance of the given standardized selfrestrained tests and first results about the transferability of results onto real parts are discussed. The influence of the test specimen geometry on the restraint conditions of the test is investigated for a selected test with numerical Simulation using commercial FEA software. Additionally, the residual stresses caused by the welding process are measured and linked with the restraint conditions which are defined mainly by the geometry parameters. Finally the transferability of the selected cold cracking test results is validated experimentally. The test results of a multilayer weld on high-strength fine grained steel of real size weldments are investigated. For these experiments a 16 MN large scale testing facility is used which is capable of applying the high reaction forces and clamping conditions found at large scale demonstrator parts. The results show the importance of the quantitative knowledge of the restraint conditions and the welding residual stresses on the cold cracking resistance. T2 - 8th International Conference on Trends in Welding Research CY - Pine Mountain, USA DA - 01.06.2008 KW - Cold Cracking Test KW - Intensity of Restraint PY - 2008 DO - https://doi.org/10.1361/cp2008twr766 SP - 766 EP - 771 PB - ASM international AN - OPUS4-47623 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Gebhardt, Moritz Oliver A1 - Quiroz Penaranda, Vanessa A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael ED - Cerjak, H. ED - Enzinger, N. T1 - Restraint effects on stresses and strains in single-run high power laser beam welding of thick plates KW - Laserstrahlschweißen KW - Heißrisse KW - Einspannung PY - 2010 SN - 978-3-85125-127-2 SP - 1011 EP - 1033 PB - Verlag der Technischen Universität Graz AN - OPUS4-23301 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Quiroz, V. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Saldabilita di lamiere in acciaio inossidabile austenico ed austeno-ferritico ad alto contenuto di manganese con processo laser N2 - Manganese alloyed stainless steels represent a cost-effective alternative to conventional CrNi- stainless steels due to strong fl uctuations of the market prices for nickel seen during the last years. In CrMnNi steels, nickel is partially replaced by lower-cost manganese and small amounts of nitrogen for stabilization of the austenitic phase. This also brings benefi ts regarding the mechanical properties, as it results in an increased material strength. Laser beam welding of such materials was investigated for direct comparison with Standard CrNi steels. Main emphasis was laid on fi nding adequate process parameters to achieve a stable welding process and obtain a good weld quality. Two different laser sources, a 4.4 kW Nd:YAG and a 5 kW CO2 laser, were used to weld 1.5 mm stainless steel sheets in continuous wave mode. A high-Mn austenitic (1.4376) and a lean duplex (1.4162) steel, as well as the standard austenitic (1.4301) and duplex (1.4362) grades were selected as test materials. Both butt and lap joint confi gurations were studied. Experiments were carried out systematically, varying the welding speed, laser power and focal point position in order to determine adequate process windows. The infl uence of the shielding gas type and fl ow rate on the process stability and the weld quality were investigated. The effects of weld edge preparation on the weld appearance and quality levels attained were also examined. The obtained welded joints were subjected to radiographic tests for detection of internal imperfections. Also a metallurgical characterization of the samples regarding the resulting phase composition or balance and hardness depending on the welding process parameters was conducted. Furthermore, tensile and potentiodynamic tests were performed to evaluate the mechanical and corrosion properties, respectively. The results provide an insight into the advantages and limitations of the laser beam welding process for joining high-manganese alloyed stainless steels. Conditions for the production of defect-free and corrosion-resistant welds having good mechanical properties could be determined. KW - Weldability KW - Austenitic stainless steels KW - Corrosion KW - CO2 lasers KW - Duplex stainless steels KW - Laser welding KW - Manganese KW - Mechanical properties KW - Shielding gases KW - YAG lasers PY - 2016 SN - 0035-6794 VL - 68 IS - 1 SP - 33 EP - 43 AN - OPUS4-38100 LA - ita AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Petrat, T. A1 - Rethmeier, Michael ED - Rethmeier, Michael T1 - Schicht für Schicht Auftragsschweißen dreidimensionaler Körper N2 - Die Anwendung der additiven Fertigung nimmt stark zu. Eine neue Designfreiheit erlaubt es hier den Konstrukteurinnen und Konstrukteuren, die Bauteilfunktion in den Vordergrund der Entwicklungen zu stellen. Leichtbaustrukturen sowie Funktionsintegration machen es möglich, vormals Bauteile aus vielen Einzelkomponenten jetzt in einem einzigen Bauteil zu vereinigen. Experten am Fraunhofer IPK qualifizieren das Laser-Pulver-Auftragschweißen für die additive Fertigung und legen dabei besonderen Wert auf die Automatisierung des Verfahrens. KW - Laser-Pulver-Auftragsschweißen PY - 2016 SN - 1438-1125 IS - 1 SP - 18 EP - 19 AN - OPUS4-38746 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Gook, Sergej A1 - Gumenyuk, Andrey A1 - Stelling, Karen A1 - Lammers, Marco A1 - Rethmeier, Michael T1 - Schweißen im Dickblechbereich mit einem 20-kW-Faserlaser T2 - Große Schweißtechnische Tagung - BMBF-Forschungsförderung "Fügen im Produktlebenszyklus" - Studentenkongress CY - Dresden, Deutschland DA - 2008-09-17 PY - 2008 SN - 978-3-87155-256-4 N1 - Serientitel: DVS-Berichte – Series title: DVS-Berichte VL - 250 SP - 264 EP - 270 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-18706 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael T1 - Schweißen mit dem Faserlaser T2 - Laserverbund Berlin/Brandenburg, BAM CY - Berlin, Germany DA - 2007-01-18 PY - 2007 AN - OPUS4-15885 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael T1 - Schweißen mit dem Faserlaser T2 - 11. IFS-Kolloquium CY - Braunschweig, Germany DA - 2007-10-12 PY - 2007 AN - OPUS4-21827 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Biegler, M. A1 - El-Sari, B. A1 - Rethmeier, Michael A1 - Finus, F. T1 - Schweißen unter Zug – LME-Eingangsprüfung für die Autoindustrie N2 - Der Trend zum Leichtbau und die Transformation zur E-Mobilität in der Automobilindustrie befeuern die Entwicklung neuer hochfester Stähle für den Karosseriebau. Derartige Werkstoffe sind beim Widerstandspunktschweißen besonders rissanfällig (LME). Das Schweißen unter Zug stellt eine effektive Methode um die LME-Anfälligkeit unterschiedlicher Werkstoffe qualitativ zu bestimmen. KW - Automobilindustrie KW - Widerstandspunktschweißen KW - Liquid Metal Embrittlement KW - Zinkbeschichtung KW - Hochfester Stahl PY - 2021 IS - 6 SP - 54 EP - 55 AN - OPUS4-54057 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -