TY - JOUR A1 - Karkhin, Victor A1 - Pittner, Andreas A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - Simulation of inverse heat conduction problems in fusion welding with extended analytical heat source models N2 - The paper presents bounded volume heat sources and the corresponding functional-analytical expressions for the temperature field. The power density distributions considered here are normal, exponential and parabolic. The sources model real heat sources like the welding arc, laser beam, electron beam, etc., the convection in the weld pool as well as the latent heat due to fusion and solidification. The parameters of the heat source models are unknown a priori and have to be evaluated by solving an inverse heat conduction problem. The functional-analytical technique for calculating 3D temperature fields in butt welding is developed. The proposed technique makes it possible to reduce considerably the total time for data input and solution. It is demonstrated with an example of laser beam welding of steel plates. KW - Laser beam welding KW - Volume heat source KW - Functional-analytical solution KW - Inverse modelling PY - 2011 DO - https://doi.org/10.1007/s11706-011-0137-1 SN - 2095-025X SN - 2095-0268 VL - 5 IS - 2 SP - 119 EP - 125 PB - Springer CY - Secaucus, N.J. AN - OPUS4-24164 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karkhin, Victor A1 - Pittner, Andreas A1 - Schwenk, Christopher A1 - Rethmeier, Michael ED - Halmoy, E. T1 - Simulation of the temperature field in laser beam welding by inverse technique N2 - This paper presents volume heat sources and the corresponding functional analytical Solutions for the transient temperature field. The considered energy distributions are normal, exponential and parabolic. The method follows the common approach in Computational Welding Mechanics (CWM) to account for the physics of the welding process and the resulting temperature field by phenomenological models for heat conduction. Therefore, the used heat source models are apparent heat sources that incorporate the real heat input as well as the fluid flow in the weld pool and the latent heat connected with phase transformations. The heat source models provide welding characteristics like thermal cycle and Fusion line in the cross section within short computational time. Consequently, inverse techniques on basis of optimisation algorithms enable the adaptation of the models to the experimental data efficiently. Furthermore, the direct evaluation of the energy distribution for the experimental fusion line in the cross section is demonstrated which enhances the numerical optimisation by reducing the number of unknown model Parameters and providing a reasonable initial guess within the model parameter space. The proposed temperature field models are validated with real laser beam welding experiments. T2 - 13th Conference on laser materials processing in the nordic countries CY - Trondheim, Norway DA - 27.06.2011 KW - Volume heat source KW - Inverse modelling KW - Functional analysis KW - Laser beam welding PY - 2011 SP - 223 EP - 234 AN - OPUS4-24165 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Su, H. A1 - Wu, Chuan Song A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Simultaneous measurement of tool torque, traverse force and axial force in friction stir welding N2 - Simultaneous measurement of the tool torque, traverse force and axial force during friction stir welding process is of great significance to the understanding of the underlying process mechanism and the optimizing of the process parameters. Different from the traditional measurement methods using load cell or rotating component dynamometer, an indirect but economical methodology is used in this study for the simultaneous measurement of the traverse force, axial force and tool torque by monitoring the output torques of the servo motors and main spindle three-phase AC induction motor inside the FSW machine. The values of the traverse force, axial force and tool torque are determined under different welding conditions, and the influencing factors are examined. The measured results in friction stir welding of AA2024-T4 aluminum alloys at different combinations of tool rotation speed and welding speed lay foundation for process optimization. KW - Friction stir welding KW - Measurement KW - Traverse force KW - Axial force KW - Tool torque PY - 2013 DO - https://doi.org/10.1016/j.jmapro.2013.09.001 SN - 0278-6125 SN - 1526-6125 VL - 15 IS - 4 SP - 495 EP - 500 PB - Elsevier Ltd. CY - Dearborn, Mich., USA AN - OPUS4-29688 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gumenyuk, Andrey A1 - Üstündağ, Ömer A1 - Pelz, Till A1 - Bakir, Nasim A1 - Gerhards, Benjamin A1 - Schleser, Markus A1 - Rethmeier, Michael T1 - Single pass laser vacuum welding of thick steel plates using electromagnetic support N2 - The increasing demand for renewable energy produced by offshore wind turbines goes along with an increased demand in the production of offshore wind turbine foundations, so called “monopiles”, which are made by joining thick metal sheets. The industrial standard of multi-layer submerged arc welding (SAW) for joining of thick metal sheets is the current bottleneck in the production of monopiles. A possible increase in productivity by the implementation of high-power laser welding in a newly developed mobile vacuum chamber (MoVac) and an electromagnetic root support is the subject of this study. Single run butt welds are performed in flat position on S355 mild steel of thicknesses up to 80 mm using a disc laser system with 1030 nm wavelength and a maximum output of 60 kW. The laser optic is fixed on the MoVac-System which is held and manipulated by an articulated robot. KW - Laser beam welding KW - Laser welding with mobile vacuum PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612068 DO - https://doi.org/10.1016/j.procir.2024.08.145 VL - 124 SP - 418 EP - 423 PB - Elsevier BV AN - OPUS4-61206 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael T1 - Single pass laser vacuum welding of thick steel plates using electromagnetic support N2 - The increasing demand for renewable energy produced by offshore wind turbines goes along with an increased demand in the production of offshore wind turbine foundations, so called “monopiles”, which are made by joining thick metal sheets. The industrial standard of multi-layer submerged arc welding (SAW) for joining of thick metal sheets is the current bottleneck in the production of monopiles. A possible increase in productivity by the implementation of high-power laser welding in a newly developed mobile vacuum chamber (MoVac) and an electromagnetic root support is the subject of this study. Single run butt welds are performed in flat position on S355 mild steel of thicknesses up to 80 mm using a disc laser system with 1030 nm wavelength and a maximum output of 60 kW. The laser optic is fixed on the MoVac-System which is held and manipulated by an articulated robot. T2 - 13th CIRP Conference on Photonic Technologies [LANE 2024] CY - Fürth, Germany DA - 16.09.2024 KW - Laser beam welding KW - Laser welding with mobile vacuum PY - 2024 AN - OPUS4-62416 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael T1 - Single pass laser vacuum welding of thick steel plates using electromagnetic support N2 - The increasing demand for renewable energy produced by offshore wind turbines goes along with an increased demand in the production of offshore wind turbine foundations, so called “monopiles”, which are made by joining thick metal sheets. The industrial standard of multi-layer submerged arc welding (SAW) for joining of thick metal sheets is the current bottleneck in the production of monopiles. A possible increase in productivity by the implementation of high-power laser welding in a newly developed mobile vacuum chamber (MoVac) and an electromagnetic root support is the subject of this study. Single run butt welds are performed in flat position on S355 mild steel of thicknesses up to 80 mm using a disc laser system with 1030 nm wavelength and a maximum output of 60 kW. The laser optic is fixed on the MoVac-System which is held and manipulated by an articulated robot. T2 - 13th CIRP Conference on Photonic Technologies [LANE 2024] CY - Furth, Germany DA - 15.09.2024 KW - Laser beam welding KW - Laser welding with mobile vacuum PY - 2024 AN - OPUS4-62413 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Üstündag, Ö. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Single-pass Hybrid Laser Arc Welding of Thick Materials Using Electromagnetic Weld Pool Support N2 - Hybrid laser-arc welding process allows single-pass welding of thick materials, provides good quality formation of joints with minimal thermal deformations and a high productivity in comparison with arc-based welding processes. Nevertheless, thick-walled steels with a thickness of 20 mm or more are still multi-pass welded using arc welding processes, due to increased process instability by increasing laser power. One limitation factor is the inadmissible formation of gravity drop-outs at the root. To prevent this, an innovative concept of electromagnetic weld pool support is used in this study. With help of such system a stable welding process can be established for 25 mm thick steel plates and beyond. Sound welds could be obtained which are tolerant to gaps and misalignment of the welded parts. The adaptation of this system to laser and hybrid laser-arc welding process can dramatically increase the potential field of application of these technologies for real industrial implementation. T2 - Lasers in Manufacturing Conference 2019 CY - Munich, Germany DA - 24.06.2019 KW - Full Penetration KW - Hybrid Laser Arc Welding KW - Electromagnetic Weld Pool Support KW - Thick Materials PY - 2019 SP - 1 EP - 8 PB - WLT Wissenschaftliche Gesellschaft Lasertechnik e.V. AN - OPUS4-48971 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael T1 - Single-pass Hybrid Laser Arc Welding of Thick Materials Using Electromagnetic Weld Pool Support N2 - Hybrid laser-arc welding process allows single-pass welding of thick materials, provides good quality formation of joints with minimal thermal deformations and a high productivity in comparison with arc-based welding processes. Nevertheless, thick-walled steels with a thickness of 20 mm or more are still multi-pass welded using arc welding processes, due to increased process instability by increasing laser power. One limitation factor is the inadmissible formation of gravity drop-outs at the root. To prevent this, an innovative concept of electromagnetic weld pool support is used in this study. With help of such system a stable welding process can be established for 25 mm thick steel plates and beyond. Sound welds could be obtained which are tolerant to gaps and misalignment of the welded parts. The adaptation of this system to laser and hybrid laser-arc welding process can dramatically increase the potential field of application of these technologies for real industrial implementation. T2 - Lasers in Manufacturing Conference 2019 CY - Munich, Germany DA - 24.06.2019 KW - Full Penetration KW - Hybrid Laser Arc Welding KW - Electromagnetic Weld Pool Support KW - Thick Materials PY - 2019 AN - OPUS4-48975 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 - Solidification cracking in laser GMA hybrid welding of thick-walled parts N2 - Laser GMA hybrid welds, producing partial penetration, were conducted on stiff tubes made of S460NH. Experiments, using a design-of-experiments plan were conducted to examine the influence of the welding parameters on the occurrence of solidification cracks. Results say that cracks diminish, when high levels of arc power are applied, while their number increases with rising laser beam power. The weld velocity had no measurable impact. KW - Laser hybrid welding KW - Solidification cracking KW - Partial penetration welding KW - Tube welding KW - Thick walled parts KW - Design of experiments PY - 2014 DO - https://doi.org/10.1179/1362171813Y.0000000171 SN - 1362-1718 SN - 1743-2936 VL - 19 IS - 3 SP - 209 EP - 213 PB - Maney CY - London AN - OPUS4-30297 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schempp, Philipp A1 - Cross, C.E. A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Solidification of GTA aluminium weld metal: Part 2 - Thermal conditions and model for columnar-to-equiaxed transition KW - Aluminium KW - Gas tungsten arc welding (GTAW) KW - Columnar to equiaxed transition (CET) KW - Thermal analysis PY - 2014 SN - 0043-2296 SN - 0096-7629 VL - 93 IS - March SP - 69-s - 77-s PB - American Welding Society CY - New York, NY AN - OPUS4-30415 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schempp, Philipp A1 - Cross, C.E. A1 - Pittner, Andreas A1 - Oder, Gabriele A1 - Neumann, R. S. A1 - Rooch, Heidemarie A1 - Dörfel, Ilona A1 - Österle, Werner A1 - Rethmeier, Michael T1 - Solidification of GTA aluminium weld metal: Part I - Grain morphology dependent upon alloy composition and grain refiner content N2 - The solidification conditions during welding strongly influence the weid metal microstructure and mechanical properties of a weid. In the first part of this study, the grain morphology of gas tungsten arc (GTA) bead-on-plate welds was investigated for the aluminum Alloys 1050A (Al 99.5), 6082 (Al SifMgMn), and 5083 (AI Mg4.5Mn0.7). The experiments revealed that increasing welding speed and alloy content allow the growth of small, equiaxed grains, particularly in the weid center. Furthermore, increasing grain refiner additions led to a Strong reduction of the weid metal mean grain size and hence facilitated the columnar to equiaxed transition (CET). In addition, wavelength dispersive X-ray spectroscopy (WDS) and transmission electron microscopy (TEM) analysis revealed in the weid metal TiB2 particles that were surrounded by Al3Ti. This suggests the duplex nucleation theory for nucleation of aluminum grains in GTA weid metal. KW - Aluminium KW - Gas tungsten arc welding (GTAW) KW - Grain refinement KW - Columnar to equiaxed transition (CET) KW - Epitaxial nucleation KW - Duplex nucleation theory PY - 2014 SN - 0043-2296 SN - 0096-7629 VL - 93 SP - 53-s EP - 59-s PB - American Welding Society CY - New York, NY AN - OPUS4-30413 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Uspenskiy, S.A. A1 - Shcheglov, Pavel A1 - Petrovskiy, V.N. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Spectral diagnostics of a vapor-plasma plume produced during welding with a high-power ytterbium fiber laser N2 - We have conducted spectroscopic studies of the welding plasma formed in the process of welding with an ytterbium fiber laser delivering output power of up to 20 kW. The influence of shielding gases (Ar, He) on different parts of the welding plume is investigated. The absorption coefficient of the laser radiation by the welding-plume plasma is estimated. Scattering of 532-nm probe radiation from particles of the condensed metal vapor within the caustic of a high-power fiber laser beam is measured. Based on the obtained results, conclusions are made on the influence of the plasma formation and metal vapor condensation on the radiation of the high-power fiber laser and the stability of the welding process. PY - 2013 DO - https://doi.org/10.1134/S0030400X13070205 SN - 0030-400X SN - 1562-6911 VL - 115 IS - 1 SP - 140 EP - 146 PB - MAIK Nauka/Interperiodica Publ. / Pleiades Publishing, Ltd. CY - Moscow AN - OPUS4-28983 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weber, Gert A1 - Rethmeier, Michael T1 - Spot welding and weldbonding of high strength steels for lightweight auto body manufacturing N2 - The resistance spot weiding procedure is one of the most important joining technique in lightweight car body shell mass production. Especially for newly developed ultra high strength steels (UHSS) and advanced high strength steels (AHSS), this joining technique has more advantages than other thermal and mechanical joining procedures for thin Steel sheets. Additionally, the technique of adhesive bonding and its combination with the technique of resistance spot weiding called weldbonding becomes more and more important. The weldbonding affords many advantages, e.g. improved crash performance, fatigue behaviour and corrosion resistance. The main target of the contribution is to show the influence of different joined ultra and advanced high strength steels on the process reliability for both the resistance spot weiding process and the weldbonding process. In this connection the influence of surface conditions of the steel sheets, the applied adhesive and the choice of the weiding parameters on the process reliability will be studied. The results for the weldbonding procedure are based on different adhesives. Based on the representation of weiding current ranges by weldability lobes, Statements concerning the weldbonding process reliability for some special AHSS and UHSS will be given. The mechanical behaviour of spot welded and weldbonded joints for different AHSS and UHSS will be studied. T2 - EUROJOIN 8 - 8th European conference CY - Pula, Croatia DA - 24.05.2012 KW - Spot welding KW - Weldbonding KW - High strength steels KW - Process reliability KW - Mechanical properties of joints PY - 2012 SP - 633 EP - 643 AN - OPUS4-26383 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Marko, A. A1 - Graf, B. A1 - Rethmeier, Michael T1 - Statistical analysis of weld bead geometry in Ti6Al4V laser cladding N2 - The process of laser cladding has become more important during recent years because of its broad application for cladding, repair or additive manufacturing. In the field of mechanical engineering, one use is the repair of turbine blades. For high quality and reliability of the repaired components, it is necessary to adjust the weld bead geometry to the specific repair task. The bead geometry influences the metallurgical bonding and the degree of dilution as well as the formation of defects like pores or cracks. Therefore, it is important to know the effects of the different parameters on the welding bead. A valuable tool to meet this industrial challenge is the design of experiments (DoE). In this context, the user can choose between a huge number of test plans. Greater Profit of information is expected by a larger test range. In order to confirm the acceptance, a five-step full factorial test plan is compared to a central composite design in this paper. Moreover, the limits of the experimental range are indicated and restrictions can be derived. As the results show, the essential effects are detected with a full factorial test plan as well as with a central composite design. Merely the effect strength could not always be specified unambiguously. On this account and in consideration of cost efficiency, the use of central compound design is recommended in industrial applications. KW - Laser metal deposition KW - Design of experiments KW - Laser cladding KW - Cladding parameter KW - Additive manufacturing PY - 2017 DO - https://doi.org/10.3139/120.111077 SN - 0025-5300 SN - 2195-8572 VL - 59 IS - 10 SP - 837 EP - 843 PB - Carl Hanser Verlag CY - München AN - OPUS4-42882 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Huo, W. A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael A1 - Wolter, K. T1 - Strain Prediction Using Deep Learning during Solidification Crack Initiation and Growth in Laser Beam Welding of Thin Metal Sheets N2 - The strain field can reflect the initiation time of solidification cracks during the welding process. The traditional strain measurement is to first obtain the displacement field through digital image correlation (DIC) or optical flow and then calculate the strain field. The main disadvantage is that the calculation takes a long time, limiting its suitability to real-time applications. Recently, convolutional neural networks (CNNs) have made impressive achievements in computer vision. To build a good prediction model, the network structure and dataset are two key factors. In this paper, we first create the training and test sets containing welding cracks using the controlled tensile weldability (CTW) test and obtain the real strain fields through the Lucas–Kanade algorithm. Then, two new networks using ResNet and DenseNet as encoders are developed for strain prediction, called StrainNetR and StrainNetD. The results show that the average endpoint error (AEE) of the two networks on our test set is about 0.04, close to the real strain value. The computation time could be reduced to the millisecond level, which would greatly improve efficiency. KW - Convolutional neural network KW - Strain fields prediction KW - Laser beam welding KW - Solidification cracking PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-570565 DO - https://doi.org/10.3390/app13052930 VL - 13 IS - 5 SP - 1 EP - 15 PB - MDPI AN - OPUS4-57056 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neubert, S. A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Strain-rate controlled Gleeble experiments to determine the stress-strain behavior of HSLA steel S960QL N2 - In order to generate a material data base for computational welding mechanics, temperature and strain-rate dependent stress-strain experiments were performed by using a Gleeble®3500 testing system. The object of the investigation was HSLA transformable steel S960QL and related solid phases as bainite, martensite and austenite. For the production of these solid phases, the base material was heat treated according to an average weld temperature cycle which was extracted within the heat affected zone of a thermal numerical weld simulation of a GMA weld. The hot tensile tests were carried out via cost-saving flat specimen geometries. Two experimental series with different strain-rates were conducted, where the longitudinal strain-rate was controlled by specification of the transversal strain-rate applying Poisson’s-ratio. Subsequently, the resulting stress-strain curves were approximated in accordance with the Ramberg-Osgood-materials law. Consequently, it is shown that the temperature and strain-rate dependent stress-strain behavior of metals can be successfully characterized by means of a Gleeble®-system. However, this requires a control of the longitudinal strain-rate by specification of the transversal strain-rate. The related experimental procedure and the method of evaluation are explained in detail. With regard to all tested solid phases, a significant strain-rate dependency can only be observed upwards from temperatures of 400 °C. Based on experimental results, Ramberg-Osgood-parameters will be presented to describe the stress-strain behavior of steel S960QL and related solid phases for temperatures between 25 °C and 1200 °C. Furthermore, the use of costsaving flat specimen-geometry appears reasonable. N2 - Für die Generierung einer Materialdatenbank zur Schweißstruktursimulation wurden temperatur- und dehnratenabhängige Spannungs-Dehnungsexperimente unter Einsatz einer Gleeble® 3500-Anlage durchgeführt. Als Untersuchungsgegenstand diente der hochfeste niedriglegierte Feinkornbaustahl S960QL und seine zugehörigen Festphasen Bainit, Martensit und Austenit. Zur Herstellung dieser Festphasen wurde der Grundwerkstoff Wärmebehandlungen ausgesetzt, welche die charakteristischen Merkmale eines durchschnittlichen Schweißzeittemperaturzyklus aufweisen. Dieser Temperaturzyklus wurde aus der Wärmeeinflusszone eines numerisch nachgebildeten Temperaturfeldes einer MAG-Schweißverbindung extrahiert. Die Zugversuche wurden an einer kostengünstig herzustellenden Flachprobengeometrie durchgeführt, wobei zwei Experimentalreihen mit jeweils unterschiedlichen Dehnraten realisiert wurden. Die resultierenden Spannungs-Dehnungskurven wurden durch die Ramberg-Osgood-Beziehung approximiert. Es konnte gezeigt werden, dass das temperatur- und dehnratenabhängige Spannungs-Dehnungsverhalten von Metallen durch die Anwendung eines Gleeble®-Systems erfolgreich charakterisiert werden kann. Die Einstellung der Längsdehnrate muss dabei durch die Kontrolle der Querdehnrate unter Berücksichtigung des Poisson-Verhältnisses erfolgen. Die experimentellen Prozeduren und die zugehörigen Auswertemethodiken wurden detailliert erläutert. Für alle getesteten Festphasen wurde ein signifikanter Dehnrateneinfluss erst für Temperaturen ab 400 °C aufwärts beobachtet. Die anhand der Messergebnisse abgeleiteten Ramberg-Osgood-Parameter zur Beschreibung des Verfestigungsverhaltens für den Temperaturbereich zwischen 25 °C und 1200 °C werden vollständig präsentiert. KW - Stress-strain behavior KW - Gleeble testing KW - HSLA KW - Strain-rate KW - Numerical welding simulation KW - Transformable steels PY - 2018 DO - https://doi.org/10.3139/120.111208 SN - 0025-5300 VL - 60 IS - 7-8 SP - 733 EP - 748 PB - Carl Hanser CY - München AN - OPUS4-45791 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schwenk, Christopher A1 - Rethmeier, Michael ED - Cerjak, H. ED - Enzinger, N. T1 - Structured approach for a transient 3D numerical welding simulation KW - Numerical welding simulation KW - Experimental validation KW - Temperature field KW - Welding distortion KW - Residual stress PY - 2010 SN - 978-3-85125-127-2 SP - 901 EP - 917 PB - Verlag der Technischen Universität Graz AN - OPUS4-23153 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weber, Gert A1 - Brauser, Stephan A1 - Gaul, Holger A1 - Rethmeier, Michael T1 - Study of fatigue behavior for spot welded tensile shear specimens of advanced high strength steels N2 - For automotive body-in-white applications the influence of manufacture-related gaps between the steel sheets and also of manufacture-related surface cracks on the fatigue behavior of tensile shear specimens for spot welded TRIP steel was analyzed. It was shown that gaps between the steel sheets reduce the fatigue strength, whereas the fatigue behavior is neither influenced by cracks in the electrode indentation area nor in the heat effected zone. KW - Automotive manufacteuring KW - Fatigue behavior KW - TRIP Steel HCT690T PY - 2012 DO - https://doi.org/10.1002/srin.201100286 SN - 1611-3683 SN - 0177-4832 VL - 83 IS - 10 SP - 988 EP - 994 PB - Verl. Stahleisen CY - Düsseldorf AN - OPUS4-27632 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Üstündag, Ö. A1 - Fritzsche, André A1 - Avilov, V. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Study of gap and misalignment tolerances at hybrid laser arc welding of thick-walled steel with electromagnetic weld pool support system N2 - The hybrid laser arc welding (HLAW) process provides many advantages such as improved gap bridgeability, deep penetration and misalignment of edges, that is why the process is used increasingly in industrial applications e.g. shipbuilding, power plant industry and line-pipe manufacturing. The obvious encountered problem for single pass welding in flat position is the gravity drop-out at low welding velocities. With the usage of an electromagnetic weld pool support system, which is based on generating Lorentz forces within the weld pool, wide seams followed by reduced welding velocities could be achieved in this study leading to the realization of a gap bridgeability up to 1 mm, misalignment of edges up to 2 mm and a single pass weld up to 28 mm thickness with a 20-kW fibre laser. These developments expand the boundaries of the HLAW process for different industrial applications. As a result, less accurate preparation of the edges would be sufficient, which saves time for manufacturing. KW - Hybrid laser-arc welding KW - Electromagnetic weld pool support system KW - Thick-walled steel KW - Gap bridgeability KW - Single pass welding KW - Misalignment of edges PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-468263 DO - https://doi.org/10.1016/j.procir.2018.08.016 SN - 2212-8271 VL - 74 SP - 757 EP - 760 PB - Elsevier AN - OPUS4-46826 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Study on Duplex Stainless Steel Powder Compositions for the Coating of thick Plates of Laser Beam Welding N2 - Duplex stainless steels combine the positive properties of its two phases, austenite and ferrite. Due to its good corrosion resistance, high tensile strength, and good ductility, it has multiple applications. But laser beam welding of duplex steels changes the balanced phase distribution in favor of ferrite. This results in a higher vulnerability to corrosion and a lower ductility. Herein, different powder combinations consisting of duplex and nickel for coating layers by laser metal deposition (LMD) are investigated. Afterward, laser tracks are welded, and the temperature cycles are measured. The ferrite content of the tracks is analyzed by feritscope, metallographic analysis, and electron backscatter diffraction. The goal is the development of a powder mixture allowing for a duplex microstructure in a two-step process, where first the edges of the weld partners are coated with the powder mixture by LMD and second those edges are laser beam welded. The powder mixture identified by the pretests is tested in the two-step process and analyzed by metallographic analysis, energy-dispersive X-ray spectroscopy, and Vickers hardness tests. The resulting weld seams show a balanced duplex microstructure with a homogenous nickel distribution and a hardness of the weld seam similar to the base material. KW - Duplex AISI 2205 KW - Laser metal deposition KW - Laser beam welding KW - Nickel KW - Stainless steels PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-547024 DO - https://doi.org/10.1002/adem.202101327 SN - 1438-1656 SP - 1 EP - 11 PB - Wiley-VCH CY - Weinheim AN - OPUS4-54702 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Study on Duplex Stainless Steel Powder Compositions forthe Coating of Thick Plates for Laser Beam Welding N2 - Duplex stainless steels combine the positive properties of its two phases, austenite and ferrite. Due to its good corrosion resistance, high tensile strength and good ductility it has multiple applications. But laser beam welding of duplex steels changes the balanced phase distribution in favor of ferrite. This results in a higher vulnerability to corrosion and a lower ductility. In this study different powder combinations consisting of duplex and nickel for coating layers by laser metal deposition are investigated. Afterwards laser tracks are welded, and the temperature cycles measured. The ferrite content of the tracks are analyzed by feritscope, metallographic analysis and Electron Backscatter Diffraction. The goal is the development of a powder mixture allowing for a duplex microstructure in a two-step process, where firstly the edges of the weld partners are coated with the powder mixture by LMD and secondly those edges are laser beam welded. The powder mixture identified by the pretests is tested in the two-step process and analyzed by metallographic analysis, energy dispersive X-ray spectroscopy and Vickers hardness tests. The resulting weld seams show a balanced duplex microstructure with a homogenous nickel distribution and a hardness of the weld seam similar to the base material. KW - Duplex AISI 2205 KW - Stainless Steel KW - Laser Beam Welding KW - Nickel KW - Laser Metal Deposition PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-554663 DO - https://doi.org/10.1002/adem.202101327 SN - 1438-1656 VL - 24 IS - 6 SP - 1 EP - 11 PB - Wiley-VCH CY - Weinheim AN - OPUS4-55466 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Polami, S.M. A1 - Häfele, P. A1 - Rethmeier, Michael A1 - Schmid, A. T1 - Study on fatigue behavior of dissimilar materials and different methods of friction-welded joints for drive pinion in trucks N2 - This work addresses the fatigue strength of friction-welded joints for the drive pinion in heavy-duty trucks. Three different friction welding (FW) variants were tested for the joint between the pinion and the bevel of the shaft: (1) conventional FW using series materials, (2) conventional FW from dissimilar materials for every part, and (3) dissimilar joints by applying joint-site structure of FW. Each joint variant was compared to the series production part using a 4-point bending test. Results showed that the higher strength material slightly improved the fatigue strength of the conventional friction-welded joints. Despite the light weight of the component joined structurally at the site, the joint revealed a lower endurance limit compared to other variants. However, there has been little discussion on the weld zone position. The applied equivalent stresses on the weld zone of the joint-site structure are less similar to the position for the conventional FW. Characterization of the failure explains the extraordinary behaviors in relation to S-N curves. PY - 2015 DO - https://doi.org/10.1007/s40194-015-0258-8 SN - 0043-2288 SN - 1878-6669 VL - 59 IS - 6 SP - 917 EP - 926 PB - Springer CY - Oxford AN - OPUS4-34841 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Muhammad, S. A1 - Han, S.W. A1 - Na, S.J. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Study on the role of recondensation flux in high power laser welding by computational fluid dynamics simulations N2 - Partial penetration welding with fiber laser on 20mm thick plates was carried out in horizontal position to study the role of secondary heating in modeling of high power fiber laser welding. Experiments were carried out using 18.8kW laser with 1.5 m/min welding speed at Ar assist gas flow rates of 0, 17, 29, and 40 l/min, all four cases show similar bead shape with bright emission of vapor plume. Numerical simulations were performed using volume of fluid method by considering three different models as models A–C. Model A considers only Fresnel reflection inside the keyhole using real time tracking of free surface. Model B considers vapor recondensation flux inside keyhole along with model A. Finally, model C is used, which considers vapor plume heating at 4100K temperature along with models A B. Secondary heating by recondensation and vapor plume is vital in modeling of high power fiber laser welding; especially, the upper part of the bead is more influenced due to secondary heating. Tungsten particles are also used to visualize the flow pattern of melt pool. KW - Laser keyhole welding KW - Fresnel reflection KW - Secondary heat source KW - Plume heating KW - Vapor recondensation KW - High brightness KW - High power KW - Partial penetration KW - Fiber laser PY - 2018 DO - https://doi.org/10.2351/1.4994246 SN - 1042-346X SN - 1938-1387 VL - 30 IS - 1 SP - 012013-1 EP - 012013-12 PB - Laser Institute of America CY - Orlando, Fla. AN - OPUS4-44345 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 - Study on the transition behavior of the bulging effect during deep penetration laser beam welding N2 - The present work is devoted to the study of the transition behavior of the recently confirmed widening of the weld pool, known as the bulging effect, during high-power deep penetration laser beam welding of thick unalloyed steel sheets. A three-dimensional transient multi-physics numerical model is developed, allowing for the prediction of the bulge formation and the study of its temporal behavior. The model is generalized to account automatically for the transition from partial to complete penetration. Several experimental measurements and observations, such as drilling period, weld pool length, temperature, efficiency, and metallographic cross-sections are used to verify the model and assure the plausibility of the numerical results. The analysis of the calculated temperature and velocity distributions, as well as the evolution of the keyhole geometry, shows that the formation of a bulging region strongly depends on the penetration depth of the weld. Based on the numerical results, the bulge is found to occur transiently, having its transition from a slight bulge to a fully developed bulging between penetration depths of 6 mm and 9 mm, respectively. KW - Laser beam welding KW - Deep penetration KW - Bulge formation KW - Numerical modeling PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545067 DO - https://doi.org/10.1016/j.ijheatmasstransfer.2021.122171 VL - 184 SP - 122171 PB - Elsevier Ltd. AN - OPUS4-54506 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hilgenberg, Kai A1 - Rethmeier, Michael A1 - Steinhoff, K. T1 - Surface structuring by pulsed laser implantation N2 - Micrometric surface topologies are required for a wide range of technical applications. While lowered surface features have been used for many years to improve the tribological behavior of contacting surfaces, there are also other fields of application, where the potential of elevated surface features is known, e. g. for metal forming tools. However, the demand for a high wear resistance of these structures often inhibits an industrial application. A solution is offered by structuring techniques that use additional material. A promising approach is the localized dispersing of hard ceramic particles by pulsed laser radiation, the so-called laser implantation. This paper describes the potential to adjust the geometry as well as the mechanical properties of laser implanted surfaces by means of microstructural and topological investigations. Afterwards, results of a wear test are given and different applications for this structuring technique are discussed. It can be shown that dome-shaped or ring-shaped structures on a micrometric scale can be produced with high hardness and wear resistance. T2 - THERMEC 2016: 9th International Conference on Processing & Manufacturing of Advanced Materials CY - Graz, Austria DA - 29.05.2016 KW - Surface structuring KW - Metal forming tools KW - Laser implantation KW - Laser dispersing PY - 2017 DO - https://doi.org/10.4028/www.scientific.net/MSF.879.750 SN - 1662-9752 VL - 879 SP - 750 EP - 755 PB - Trans Tech Publications CY - Schweiz AN - OPUS4-38927 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hilgenberg, Kai A1 - Rethmeier, Michael A1 - Steinhoff, K. T1 - Surface structuring by pulsed laser implantation N2 - Micrometric surface topologies are required for a wide range of technical applications. While lowered surface features have been used for many years to improve the tribological behavior of contacting surfaces, there are also other fields of application, where the potential of elevated surface features is known, e. g. for metal forming tools. However, the demand for a high wear resistance of these structures often inhibits an industrial application. A solution is offered by structuring techniques that use additional material. A promising approach is the localized dispersing of hard ceramic particles by pulsed laser radiation, the so-called laser implantation. This paper describes the potential to adjust the geometry as well as the mechanical properties of laser implanted surfaces by means of microstructural and topological investigations. Afterwards, results of a wear test are given and different applications for this structuring technique are discussed. It can be shown that dome-shaped or ring-shaped structures on a micrometric scale can be produced with high hardness and wear resistance. KW - Laser implantation KW - Surface structuring PY - 2017 DO - https://doi.org/10.4028/www.scientific.net/MSF.879.750 SN - 0255-5476 SN - 1662-9752 VL - 879 SP - 750 EP - 755 PB - Trans Tech Publications AN - OPUS4-38263 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Frei, J. A1 - Rethmeier, Michael T1 - Susceptibility of electrolytically galvanized dual-phase steel sheets to liquid metal embrittlement during resistance spot welding N2 - Modern advanced high-strength steel sheets for automotive applications are mostly zinc coated for corrosion resistance. However, the presence of zinc can—besides its positive effects—increase the material’s susceptibility to liquid metal embrittlement (LME) during resistance spot welding (RSW). Zinc and its eutectics are, due to their low melting point, present in liquid state during the welding process. This fact can, in combination with other factors like tensile strains or stresses, lead to the formation of brittle, intergranular cracks in the weld, and heat-affected zone. This phenomenon is commonly called liquid metal embrittlement. In order to understand the process from a practical perspective, one must learn what factors facilitate it. In this study, industry-relevant parameters are investigated regarding their influence on the occurrence of LME, embodied by the formation of surface cracks. It was found that electrode wear has less of an influence on the cracking susceptibility than welding current or tensile stresses. Finite element analysis is believed to provide a powerful tool in order to gain insights on the formation process. Modeling of the process shows promising initial results, revealing the underlying local stress and strain fields, unmeasurable with common techniques. KW - Resistance spot welding KW - High-strength steel sheets KW - Surface cracks KW - Liquid metal embrittlement KW - Zinc PY - 2018 DO - https://doi.org/10.1007/s40194-018-0619-1 SN - 0043-2288 SN - 1878-6669 VL - 62 IS - 5 SP - 1031 EP - 1037 PB - Springer AN - OPUS4-45775 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Sproesser, G. A1 - Change, Y.-J. A1 - Pittner, Andreas A1 - Finkbeiner, M. A1 - Rethmeier, Michael ED - Stark, R. ED - Bonvoisin, J. ED - Seliger, G. T1 - Sustainable technologies for thick metal plate welding N2 - Welding is the most important joining technology. In the steel construction industry, e.g. production of windmill sections, welding accounts for a main part of the manufacturing costs and resource consumption. Moreover, social issues attached to welding involve working in dangerous environments. This aspect has unfortunately been neglected so far, in light of a predominant focus on economics combined with a lack of suitable assessment methods. In this chapter, exemplary welding processes are presented that reduce the environmental and social impacts of thick metal plate welding. Social and environmental Life Cycle Assessments for a thick metal plate joint are conducted for the purpose of expressing and analysing the social and environmental impacts of welding. Furthermore, it is shown that state-of-the-art technologies like Gas Metal Arc Welding with modified spray arcs and Laser Arc-Hybrid Welding serve to increase social and environmental performance in contrast to common technologies, and therefore offer great potential for sustainable manufacturing. KW - Human health G. KW - Life cycle assessment (LCA) KW - Arc welding KW - Laser arc-hybrid welding KW - Resource efficiency KW - Social life cycle assessment (SLCA) PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-390025 SN - 978-3-319-48513-3 SN - 978-3-319-48514-0 DO - https://doi.org/10.1007/978-3-319-48514-0 SN - 2194-0541 SN - 2194-055X SP - 71 EP - 84 PB - Springer CY - Cham, Switzerland AN - OPUS4-39002 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sproesser, G. A1 - Schenker, S. A1 - Pittner, Andreas A1 - Borndörfer, R. A1 - Rethmeier, Michael A1 - Chang, Y.-J. A1 - Finkbeiner, M. T1 - Sustainable welding process selection based on weight space partitions N2 - Selecting a welding process for a given application is crucial with respect to the sustainability of part manufacturing. Unfortunately, since welding processes are evaluated by a number of criteria, preferences for one or the other process can be contradictory. However, the prevalent procedure of weight assignment for each criterion is subjective and does not provide information about the entire solution space. From the perspective of a decision maker it is important to be able to assess the entire set of possible weightings and answer the question which welding process is optimal for which set of weights. This issue is investigated by means of a weight space partitioning approach. Two welding processes are considered with respect to three criteria that reflect their economic and environmental performance. In order to find the most sustainable welding process the underlying weight space partition is evaluated. T2 - 13th Global Conference on Sustainable Manufacturing – Decoupling Growth from Resource Use CY - Bình Dương New City, Vietnam DA - 16.09.2015 KW - Welding costs KW - Multi-criteria decision support KW - LCA KW - Welding process selection KW - GMAW KW - Multi-attribute decision method PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-353740 DO - https://doi.org/10.1016/j.procir.2016.01.077 SN - 2212-8271 VL - 40 SP - 127 EP - 132 PB - Elsevier B.V. AN - OPUS4-35374 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Chaurasia, Prashant Kumar A1 - Fabry, Çağtay A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Tandem-GMAW: advanced pulsed and short cicuiting process mode experimental data N2 - This dataset consists of raw recordings for 5 Tandem gas metal arc welding experiments (Tandem-GMAW / T-GMAW). KW - T-GMAW KW - High power welding KW - Deposition efficiency KW - Life Cycle Assessment PY - 2025 DO - https://doi.org/10.5281/zenodo.17951724 PB - Zenodo CY - Geneva AN - OPUS4-65206 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Winterkorn, R. A1 - Petrat, T. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Temperature generation of different travel path strategies to build layers using laser metal deposition N2 - Laser Metal Deposition offers the chance to build near net shape parts. The temperature evolution within the process has an influence on track and layer geometries. There are special travel path strategies required to produce near net shape components and reduce shape deviation resulting of error propagation. This paper deals with the temperature progression of individual layers and the maximum heating of deeper substrate regions. Spiral and zig-zag strategies are examined. The investigations are carried out using S235JR as substrate and 316L as powder material. The influence of different strategies on temperature evolution is discussed. The results from the experiments show that various production strategies are associated with different temperature fields. Furthermore, the extent of the temperature variations of layer strategies and layer position are strongly dependent on the production direction. These results demonstrate the importance of developing suitable build-up strategies for parts of complex shape to ensure a stable process with constant temperature as well as even layers. T2 - Lasers in Manufacturing Conference 2017 CY - Munich, Germany DA - 26.06.2017 KW - 316L KW - Additive Manufacturing KW - Temperature behavior KW - Laser Metal Deposition KW - Stainless Steel KW - Edge effects PY - 2017 SP - 1 EP - 5 AN - OPUS4-42878 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael A1 - Artinov, Antoni A1 - Meng, Xiangmeng A1 - Bakir, Nasim A1 - Üstündag, Ömer A1 - Bachmann, Marcel A1 - Gumenyuk, Andrey T1 - The bulging effect and its relevance in high power laser beam welding N2 - The present work deals with the recently confirmed widening of the weld pool interface, known as a bulging effect, and its relevance in high power laser beam welding. A combined experimental and numerical approach is utilized to study the influence of the bulge on the hot cracking formation and the transport of alloying elements in the molten pool. A technique using a quartz glass, a direct-diode laser illumination, a high-speed camera, and two thermal imaging cameras is applied to visualize the weld pool geometry in the longitudinal section. The study examines the relevance of the bulging effect on both, partial and complete penetration, as well as for different sheet thicknesses ranging from 8 mm to 25 mm. The numerical analysis shows that the formation of a bulge region is highly dependent on the penetration depth and occurs above 10 mm penetration depth. The location of the bulge correlates strongly with the cracking location. The obtained experimental and numerical results reveal that the bulging effect increases the hot cracking susceptibility and limits the transfer of alloying elements from the top of the weld pool to the weld root. T2 - 1st Annual Assembly and Conference of The Welding Federation of Africa (TWF-Africa) CY - Cairo, Egypt DA - 14.03.2023 KW - Laser beam welding KW - Melt pool dinamics PY - 2023 AN - OPUS4-58695 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Artinov, Antoni A1 - Meng, Xiangmeng A1 - Bakir, Nasim A1 - Üstündag, Ömer A1 - Bachmann, Marcel A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - The bulging effect and its relevance in high power laser beam welding N2 - The present work deals with the recently confirmed widening of the weld pool interface, known as a bulging effect, and its relevance in high power laser beam welding. A combined experimental and numerical approach is utilized to study the influence of the bulge on the hot cracking formation and the transport of alloying elements in the molten pool. A technique using a quartz glass, a direct-diode laser illumination, a high-speed camera, and an infrared camera is applied to visualize the weld pool geometry in the longitudinal section. The study examines the relevance of the bulging effect on both, partial and complete penetration, as well as for different sheet thicknesses ranging from 8 mm to 25 mm. The numerical analysis shows that the formation of a bulge region is highly dependent on the penetration depth and occurs more frequently during partial penetration above 6 mm and complete penetration above 8 mm penetration depth, respectively. The location of the bulge correlates strongly with the cracking location. The obtained experimental and numerical results reveal that the bulging effect increases the hot cracking susceptibility and limits the transfer of alloying elements from the top of the weld pool to the weld root. T2 - 18th Nordic Laser Materials Processing Conference (18th NOLAMP) KW - High-power laser beam welding KW - Bulge effect KW - Solidification cracking KW - Multi-physical modelling KW - Metal mixing PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-539149 DO - https://doi.org/10.1088/1757-899X/1135/1/012003 VL - 1135 IS - 012003 SP - 1 EP - 11 PB - IOP Publishing AN - OPUS4-53914 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael T1 - The bulging effect and its relevance in high power laser beam welding N2 - The present work deals with the recently confirmed widening of the weld pool interface, known as a bulging effect, and its relevance in high power laser beam welding. A combined experimental and numerical approach is utilized to study the influence of the bulge on the hot cracking formation and the transport of alloying elements in the molten pool. A technique using a quartz glass, a direct-diode laser illumination, a high speed camera, and two thermal imaging cameras is applied to visualize the weld pool geometry in the longitudinal section. The study examines the relevance of the bulging effect on both, partial and complete penetration, as well as for different sheet thicknesses ranging from 8 mm to 25 mm. The numerical analysis shows that the formation of a bulge region is highly dependent on the penetration depth and occurs above 10 mm penetration depth. The location of the bulge correlates strongly with the cracking location. The obtained experimental and numerical results reveal that the bulging effect increases the hot cracking susceptibility and limits the transfer of alloying elements from the top of the weld pool to the weld root T2 - The 18th Nordic Laser Materials Processing Conference CY - Lulea, Sweden DA - 18.01.2022 KW - Laser beam welding KW - Melt pool dinamics PY - 2022 AN - OPUS4-54333 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, Xiangmeng A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Üstündag, Ömer A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - The detrimental molten pool narrowing phenomenon in wire feed laser beam welding and its suppression by magnetohydrodynamic technique N2 - Element transport in the wire feed laser beam welding (WFLBW) is directly determined by the molten pool shape and thermo-fluid flow therein. In this paper, an untypical molten pool profile, i.e., elongated at its top and bottom but narrowed at the middle, is found experimentally by real-time metal/glass observa- tion and numerically by multi-physical modeling. Ex-situ X-ray fluorescence element mapping is used to characterize the element dilution status in the fusion zone. For the first time, the detrimental influence of the molten pool narrowing on the element transport is identified and discussed, combining the exper- imental and numerical results. A magnetohydrodynamic technique is utilized to suppress the narrowing, aiming at a more homogenous element distribution. It is found that due to the interaction of the two dominant circulations from the top and bottom regions of the molten pool, a low-temperature region is formed. It leads to an untypical growth of the mushy zone, narrowing the molten pool in the middle re- gion. Its detrimental effect on material mixing is non-negligible considering the direct blocking effect on the downward flow and the premature solidification at the middle region. The Lorentz force from a trans- verse oscillating magnetic field can change the flow pattern into a single-circulation type. The downward transfer channel is widened, and its premature solidification is prevented because the low-temperature- gradient region is mitigated. This paper provides a supplementary reason regarding the common issue of insufficient material mixing during LBW, and a promising technique to optimize the process. KW - Thermo-fluid flow KW - Element transport KW - Laser beam welding KW - Magnetohydrodynamics KW - Multi-physical modeling PY - 2022 DO - https://doi.org/10.1016/j.ijheatmasstransfer.2022.122913 VL - 193 SP - 122913 PB - Elsevier B.V. AN - OPUS4-55006 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinze, Christoph A1 - Schwenk, Christopher A1 - Rethmeier, Michael T1 - The effect of tack welding on numerically calculated welding-induced distortion N2 - A single-layer pulsed gas metal arc weld of structural steel S355J2+N with a thickness of 5 mm is experimentally and numerically investigated. Two tack welds are considered in the numerical simulation into two different ways. First, the tack welds are represented by elements belonging to the initial material. This implies that the 'tack weld material' was not exposed to any thermal load or phase transformation before actual welding was performed. The weld seam is shortened and there is an influence on the stiffness of the whole structure affecting the calculation result. Secondly, the tack welds were simulated as conducted in the experimental welding procedure. The cases considering tack welding are compared to a simulation neglecting tack welding and to the experimental results. The influence of tack welds on the calculated welding-induced distortion is clarified and a contribution to an improved simulation-based prediction of welding-induced distortion is possible by modeling tack welding according to the realistic fabrication procedure. KW - Welding simulation KW - Welding-induced distortion KW - Gas metal arc welding KW - Tack welding PY - 2012 DO - https://doi.org/10.1016/j.jmatprotec.2011.09.016 SN - 0924-0136 SN - 1873-4774 VL - 212 IS - 1 SP - 308 EP - 314 PB - Elsevier CY - Amsterdam AN - OPUS4-24820 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Churiaque Bermejo, C. A1 - Sánchez-Amaya, J. M. A1 - Porrúa-Lara, M. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - The Effects of HLAW Parameters for One Side T-Joints in 15 mm Thickness Naval Steel N2 - The present contribution is the first research reporting full penetration HLAW joints in 15 mm thick EH36 steel butt T-welds with square grooves on 2F welding position by single-sided welding. The effects of welding parameters were investigated to increase the quality of the joints. Conditions leading to defect-free full penetration welds fulfilling naval regulations includes a laser power of 12.5 kW, a welding speed of 1.6 m/min and the vertical laser offset distance from the flange of 1 mm. Advanced characterization of selected welds included a microstructural identification by optical microscopy, SEM, and XRD, revealing the presence of acicular, polygonal and Widmanstätten ferrite, lath martensite, and some retained austenite at FZ. Hardness and microhardness mapping tests showed values of 155 HV at base metal and 200 to 380 HV at the fusion zone connecting the web to the flange. KW - Ship building KW - Laser beam welding KW - Hybrid laser arc welding PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523931 DO - https://doi.org/10.3390/met11040600 VL - 11 IS - 4 SP - 600 PB - MDPI CY - Basel, Switzerland AN - OPUS4-52393 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yang, K. A1 - Meschut, G. A1 - Seitz, G. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - The Identification of a New Liquid Metal Embrittlement (LME) Type in Resistance Spot Welding of Advanced High Strength Steels on Reduced Flange Widths N2 - Liquid metal embrittlement (LME) cracking is a phenomenon observed during resistance spot welding (RSW) of zinc􀀀coated advanced high􀀀strength steels (AHSS) in automotive manufacturing. In this study, severe cracks are observed at the edge of the sheet under reduced flange widths. These cracks, traversing the AHSS sheet, culminate at the edge with a width of approximately 1.2 mm. Through combined numerical and experimental investigations, and material testing, these cracks are identified and validated as a new type of LME crack. The mechanism behind this crack formation is attributed to unique geometric conditions that, when compared to center welding, amplify radial material flow by ninefold to 0.87 mm. The resultant tangential tensile stresses approximate 760 MPa, which exceed the yield strength of the examined advanced high􀀀strength steel (AHSS) under heightened temperature conditions, and when combined with liquid zinc, promote the formation of this new type of LME crack. KW - Liquid metal embrittlement KW - Crack KW - Advanced high strength steels KW - Resistance spot welding KW - Simulation KW - Flange width PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-586940 DO - https://doi.org/10.3390/met13101754 VL - 13 IS - 10 SP - 1 EP - 13 PB - MDPI AN - OPUS4-58694 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Böhne, C. A1 - Meschut, G. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - The Influence of Electrode Indentation Rate on LME Formation during RSW N2 - During resistance spot welding of zinc-coated advanced high-strength steels (AHSSs) for automotive production, liquid metal embrittlement (LME) cracking may occur in the event of a combination of various unfavorable influences. In this study, the interactions of different welding current levels and weld times on the tendency for LME cracking in third-generation AHSSs were investigated. LME manifested itself as high penetration cracks around the circumference of the spot welds for welding currents closely below the expulsion limit. At the same time, the observed tendency for LME cracking showed no direct correlation with the overall heat input of the investigated welding processes. To identify a reliable indicator of the tendency for LME cracking, the local strain rate at the origin of the observed cracks was analyzed over the course of the welding process via finite element simulation. While the local strain rate showed a good correlation with the process-specific LME cracking tendency, it was difficult to interpret due to its discontinuous course. Therefore, based on the experimental measurement of electrode displacement during welding, electrode indentation velocity was proposed as a descriptive indicator for quantifying cracking tendency. KW - Liquid Metal Embrittlement (LME) KW - Crack KW - Resistance Spot Welding (RSW) KW - Advanced High-Strength Steel (AHSS) KW - Welding Current KW - Heat Input KW - Simulation PY - 2022 DO - https://doi.org/10.29391/2022.101.015 SN - 0043-2296 VL - 101 IS - 7 SP - 197-s EP - 207-s PB - American Welding Society CY - New York, NY [u.a.] AN - OPUS4-55600 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, Xiangmeng A1 - Bachmann, Marcel A1 - Artinov, Antoni A1 - Rethmeier, Michael T1 - The influence of magnetic field orientation on metal mixing in electromagnetic stirring enhanced wire feed laser beam welding N2 - The application of the electromagnetic stirring from an oscillating magnetic field can improve the metal mixing in wire feed laser beam welding. However, the extra parameters introduced in this technique make the selection of an optimal combination of process parameters more difficult. In the current study, besides the commonly concerned magnetic flux density and frequency, the influence of the magnetic field orientation (magnetic field angle) on the transport of filler metal is studied numerically and experimentally. Ex-situ X-ray fluorescence spectrometer measurements are used to map the metal mixing in the final weld. A three-dimensional transient multi-physical model is developed to reveal the deeper physical essence, considering the coupling between heat transfer, fluid flow, keyhole dynamics, element transport and magnetohydrodynamics. The spatial distribution of the laser energy on the keyhole wall is calculated by a ray tracing algorithm. The results show that the magnetic field with smaller angle with respect to the transverse direction provides better penetration capacity, and its stirring effect can reach the lower part of the molten pool. Therefore, the smaller magnetic field angle produces better metal mixing. A constant downward flow is formed at the lower part of the molten pool when magnetic field of 10° angle is applied, which brings the filler metal to the root region. As the magnetic field angle increases to 40°, the beneficial downward flow changes into a constant upward flow, resulting in a concentration of the filler metal in the upper region. This study provides further insight of the underlying physics in the electromagnetically enhanced laser beam welding, which may guide the optimization of parameters to achieve property homogeneity or to avoid potential defects. KW - Laser welding KW - Metal mixing KW - Magnetic field KW - Magnetohydrodynamics KW - Multi-physical modelling PY - 2021 DO - https://doi.org/10.1016/j.jmatprotec.2021.117135 VL - 294 SP - 117135 PB - Elsevier B.V. AN - OPUS4-52469 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meng, Xiangmeng A1 - Putra, Stephen Nugraha A1 - Bachmann, Marcel A1 - Artinov, Antoni A1 - Rethmeier, Michael T1 - The 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 ray-tracing 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 non-continuous 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. T2 - International Congress of Applications of Lasers & Electro-Optics 2022 CY - Orlando, FL, USA DA - 17.10.2022 KW - Laser beam welding KW - laser energy distribution KW - Weld pool dynamics KW - Ray-tracing PY - 2022 SP - 1 EP - 9 AN - OPUS4-56533 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 - Theoretical study of influence of electromagnetic stirring on transport phenomena in wire feed laser beam welding N2 - The additional element from the filler wire in the laser beam welding is usually distributed inhomogeneously in the final weld due to the high solidification rate of weld pool. It has been found that the electromagnetic stirring produced by an external oscillating magnetic field can enhance the material mixing in the weld pool to achieve a more uniform element distribution. However, the magnetic field has a highly nonlinear and multicoupled interaction with the weld pool behavior, which makes the quantitative explanation of the physical mechanism difficult. In this study, the effect of electromagnetic stirring on the transport phenomena in the wire feed laser beam welding is investigated by a numerical modeling. A 3D transient multiphysical model considering the magnetohydrodynamics, heat transfer, fluid flow, keyhole dynamics, and element transport is developed. The multiple reflections and the Fresnel absorption of the laser on the keyhole wall are calculated using the ray tracing method. The numerical results show that a Lorentz force produced by the oscillating magnetic field and its induced eddy current gives significant influence on the transport phenomena in the molten pool. The forward and downward flow is enhanced by the electromagnetic stirring, which homogenizes the distribution of the additional elements from a nickel-based filler wire in a steel weld pool. The numerical results show a good agreement with the high-speed images of the molten pool, the fusion line from the optical micrograph, and the element distribution from the energy dispersive x-ray spectroscopy. This work provides a physical base for the electromagnetic-controlled laser beam welding and some guidance for the selection of electromagnetic parameters. KW - Magnetohydrodynamics KW - Molten pool dynamics KW - Element transport KW - Laser beam welding PY - 2020 DO - https://doi.org/10.2351/7.0000069 VL - 32 IS - 2 SP - 022026-1 EP - 022026-9 AN - OPUS4-50874 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Üstündag, Ömer A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Thermal Cycles and Charpy Impact Toughness of Single-Pass Hybrid Laser-Arc Welded Thick-Walled Structures N2 - The study deals with the influence of the heat input on the thermal cycles and Charpy impact toughness for hybrid laser-arc welding of 25 mm thick structural steel S355J2 using a 20-kW high-power laser in combination with an electromagnetic weld pool support. The main focus is on the change of the mechanical properties over the entire seam thickness. The cooling times were measured using a pyrometer in combination with an optical fibre in three different locations near to fusion lines corresponding to different heights of the seam. Also, Charpy impact specimens were taken from different parts of the weld joint corresponding to the different heights. The influence of the heat input was investigated for 1.8 kJ mm-1 and 3.2 kJ mm-1. 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 values could be reached in dependance on applied heat input. T2 - Lasers in Manufacturing Conference 2021 CY - Online meeting DA - 21.06.2021 KW - laser hybrid welding KW - Charpy impact toughness KW - thick plate welding KW - thermal cycles PY - 2021 SP - 1 EP - 8 AN - OPUS4-53926 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Su, H. A1 - Wu, Chuan Song A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Thermal energy generation and distribution in friction stir welding of aluminum alloys N2 - The accurate prediction of the thermal energy generation and distribution in friction stir welding process is of great significance for the optimization of the process parameters and the understanding of the underlying mechanisms. In this study, a new method of integrative calculation and measurement is proposed to obtain the more reasonable values of the frictional coefficient and the slip rate, which are both used to characterize the heat generation rate at the tool-workpiece contact interfaces. A three-dimensional model is established to fully couple the energy generation, heat transfer and material flow in friction stir welding of aluminum alloys. The energy produced by both interfacial friction and plastic deformation are taken into consideration. The analysis accuracy of the thermal energy generation and distribution is improved, and the distribution features of thermal energy density in the vicinity of the tool are elucidated. The predicted peak temperature values at some locations are in agreement with the experimentally measured ones. KW - Thermal energy generation KW - Energy density distribution KW - Heat transfer KW - Material flow KW - Friction stir welding PY - 2014 DO - https://doi.org/10.1016/j.energy.2014.09.045 SN - 0360-5442 VL - 77 SP - 720 EP - 731 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-32076 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brauser, Stephan A1 - Kromm, Arne A1 - Dabah, Eitan A1 - Kannengießer, Thomas A1 - Rethmeier, Michael T1 - Thermal stability of retained austenite in low alloyed TRIP-steel determined by high energy synchrotron radiation N2 - TRIP-steels offer a good combination between strength and ductility. Therefore TRIP-steels are widely used in the automobile industries. The aim of this work is to study the stability of involved phases during heating and to identify the kinetics of the occuring phase transformations. For that purpose, in-situ diffraction measurements, using high energy synchrotron radiation were conducted. The analysis revealed the decomposition of the metastable austenitic phase into carbide and ferrite along the heating process and the regeneration of the austenite by further heating of the sample. KW - Austenite stability KW - Phase transformation KW - TRIP steel KW - Energy dispersive synchrotron X-ray diffraction PY - 2014 DO - https://doi.org/10.4028/www.scientific.net/MSF.772.129 SN - 0255-5476 VL - 772 SP - 129 EP - 133 PB - Trans Tech Publications CY - Aedermannsdorf, Switzerland AN - OPUS4-29700 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schlichting, Joachim A1 - Brauser, Stephan A1 - Pepke, Lutz-Alexander A1 - Maierhofer, Christiane A1 - Rethmeier, Michael A1 - Kreutzbruck, Marc T1 - Thermographic testing of spot welds N2 - Spot welding is one of the most important technologies for joining sheet metal. While there are lot of approaches to non-destructive testing, quality assurance still mainly relies on welding parameter monitoring and destructive testing, leading to significant failure rates. In this paper an approach to spot weld testing using flash thermography is presented. The main focus of attention is on the identification of two typical error classes: stick welds and welds at the splash limit. Besides investigating the principal feasibility of thermography for zinc plated samples the results of a series test of spot welds joining 1 mm thick TRIP steel are shown. Based upon these results a statistical criterion is developed which allows a reliable classification of the named error classes. KW - Thermography KW - Spot welding KW - Automotive industry PY - 2012 DO - https://doi.org/10.1016/j.ndteint.2012.02.003 SN - 0963-8695 VL - 48 SP - 23 EP - 29 PB - Butterworth-Heinemann CY - Oxford AN - OPUS4-26276 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, Xiangmeng A1 - Bachmann, Marcel A1 - Yang, Fan A1 - Rethmeier, Michael T1 - Toward prediction and insight of porosity formation in laser welding: A physics-informed deep learning framework N2 - The laser welding process is an important manufacturing technology for metallic materials. However, its application is often hindered by the occurrence of porosity defects. By far, an accurate prediction of the porosity defects and an insight into its formation mechanism are still challenging due to the highly nonlinear physics involved. In this paper, we propose a physics-informed deep learning (PIDL) framework by utilizing mechanistic modeling and experimental data to predict the porosity level during laser beam welding of aluminum alloys. With a proper selection of the physical variables (features) concerning the solidification, liquid metal flow, keyhole stability, and weld pool geometry, the PIDL model shows great superiority in predicting the porosity ratio, with a reduction of mean square error by 41 %, in comparison with the conventional DL model trained with welding parameters. Furthermore, the selected variables are fused into dimensionless features with explicit physical meanings to improve the interpretability and extendibility of the PIDL model. Based on a well-trained PIDL model, the hierarchical importance of the physical variables/procedures on the porosity formation is for the first time revealed with the help of the Shapley Additive Explanations analysis. The keyhole ratio is identified as the most influential factor in the porosity formation, followed by the downward flow-driven drag force, which offers a valuable guideline for process optimization and porosity minimization. KW - Laser beam welding KW - Physics-informed deep learning KW - Porosity prediction KW - Feature fusion KW - Hierarchical importance PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-624708 DO - https://doi.org/10.1016/j.actamat.2025.120740 VL - 286 SP - 1 EP - 13 PB - Elsevier B.V. AN - OPUS4-62470 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 - Transferability of ANN-generated parameter sets from welding tracks to 3D-geometries in Directed Energy Deposition N2 - Directed energy deposition (DED) has been in industrial use as a coating process for many years. Modern applications include the repair of existing components and additive manufacturing. The main advantages of DED are high deposition rates and low energy input. However, the process is influenced by a variety of parameters affecting the component quality. Artificial neural networks (ANNs) offer the possibility of mapping complex processes such as DED. They can serve as a tool for predicting optimal process parameters and quality characteristics. Previous research only refers to weld beads: a transferability to additively manufactured three-dimensional components has not been investigated. In the context of this work, an ANN is generated based on 86 weld beads. Quality categories (poor, medium, and good) are chosen as target variables to combine several quality features. The applicability of this categorization compared to conventional characteristics is discussed in detail. The ANN predicts the quality category of weld beads with an average accuracy of 81.5%. Two randomly generated parameter sets predicted as “good” by the network are then used to build tracks, coatings,walls, and cubes. It is shown that ANN trained with weld beads are suitable for complex parameter predictions in a limited way. KW - Welding parameter KW - Quality assurance KW - DED KW - Artificial neural network KW - Additive manufacturing PY - 2022 DO - https://doi.org/10.1515/mt-2022-0054 SN - 0025-5300 VL - 64 IS - 11 SP - 1586 EP - 1596 PB - De Gruyter AN - OPUS4-56278 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Transient Process Simulation of Heat Transfer in Laser Beam Welding with an Equivalent Heat Source N2 - This paper presents a multiphysics modelling framework developed for the prediction of the three-dimensional transient temperature field of the laser welding process. The numerical model consists of two studies. In the first study, a steady-state CFD process simulation of full-penetration keyhole laser beam welding was performed. Considering the effects of, thermo-capillary and natural convection, latent heat of fusion and temperature-dependent material properties up to evaporation temperature the local weld pool geometry and temperature field were obtained. These results were used in the second subsequent study as an equivalent volumetric heat source by the prediction of the transient thermal cycle during and after fusion welding. Here the energy input and the movement of the heat source were realized by a novel technique, making use of pointwise constraints and a moving mesh provided with helper lines and additional remeshing condition. The numerically calculated results were compared to experimentally observed weld pool shapes and time-temperature curves showing a very good agreement. T2 - COMSOL Conference 2017 CY - Rotterdam, Netherlands DA - 18.10.2017 KW - High power laser beam welding KW - Transient heat transfer KW - Equivalent volumetric heat source KW - Moving mesh KW - Pointwise constraints PY - 2017 SP - 1 EP - 7 CY - Rotterdam AN - OPUS4-42701 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael T1 - Trends in European thin sheet welding N2 - 1. Steel Production and Processing in Europe 2. Design Trends in the Automotive Industry 3. Welding Technologies in the Automotive Industry 4. Problems while Processing AHSS/UHSS 5. Challenges in Joining Multi-Material Structures 6. Mechanical Joining Technologies 7. Thermal-Mechanical Joining Processes 8. Energy Efficiency of Welding Processes T2 - AWS Sheet Metal Welding Conference XVII CY - Livonia, MI, USA DA - 19.10.2016 KW - Lightweight concepts PY - 2016 AN - OPUS4-38763 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -