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 - Ullner, Christian A1 - Brauser, Stephan A1 - Subaric-Leitis, Andreas A1 - Weber, Gert A1 - Rethmeier, Michael T1 - Determination of local stress-strain properties of resistance spot-welded joints of advanced high-strength steels using the instrumented indentation test N2 - For spot-welded joints, the resistance to mechanical stress depends on the local strength properties and gradients in the weld area. The commonly used methods for investigating the stress–strain behaviour across the weld area are connected with a high level of sample preparation and with considerable limitations in local resolution. A promising method for determining locally resolved stress–strain curves is the instrumented indentation test in connection with the method of representative stress and strain (RS) and the method of artificial neural networks (NNs). The stress–strain properties of the weld nugget and the base metal determined by these two methods are compared and discussed, additionally in relation to the stress–strain curves obtained from the tensile test. The measured Vickers hardness across the weld area is compared with the evaluated local stress–strain properties. Three steels used in automobile manufacturing are investigated: mild steel DC04 and two advanced high-strength steels (TRIP steel HCT690T and martensitic steel HDT 1200M). The results of the two methods (RS and NN) show good correspondence for the base metal area but some significant differences for the weld nugget. Comparing the data across the weld area, no evidence of the presence of residual stress (which would influence the results) was found. KW - Ortsaufgelöst KW - Lokale Spannungs-Dehnungskurven KW - Punktschweißverbindung KW - Instrumentierte Eindringprüfung PY - 2012 DO - https://doi.org/10.1007/s10853-011-5936-3 SN - 0022-2461 SN - 1573-4803 VL - 47 IS - 3 SP - 1504 EP - 1513 PB - Springer Science + Business Media B.V. CY - Norwell, Mass. AN - OPUS4-25276 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Babu, N. K. A1 - Brauser, S. A1 - Rethmeier, Michael A1 - Cross, C.E. T1 - Characterization of microstructure and deformation behaviour of resistance spot welded AZ31 magnesium alloy N2 - Resistance spot welds were prepared on 3 mm thick sheets of continuous cast and rolled AZ31 magnesium alloy. The microstructure and composition analysis of weld nugget, heat affected zone (HAZ) and base metal were examined using optical and scanning electron microscopy (HR-SEM and EDS/X). The resistance spot welded magnesium alloy joints consist mainly of weld nugget and HAZ. The nugget contains two different structures, i.e. the cellular-dendritic structure at the edge of the nugget and the equiaxed dendritic structure in the centre of the nugget. The structure transition is attributed to the changes of solidification conditions. In the HAZ, grain boundary melting occurred and grain boundaries became coarse. It has been shown that hardness reduction in the weld nugget and HAZ compared with base metal is evident due to dendritic microstructure and grain growth, respectively. The results showed that spot welded joints have failed in interfacial mode under torsion and tensile–shear loading conditions. Digital image correlation during tensile–shear testing showed that low surface strains occur in the interfacial failure mode, because fracture and deformation happened primarily in the nugget area. KW - Resistance spot welding KW - AZ31 magnesium alloy KW - Microstructure KW - Hardness KW - Torsion KW - Tensile–shear PY - 2012 DO - https://doi.org/10.1016/j.msea.2012.04.021 SN - 0921-5093 SN - 1873-4936 VL - 549 SP - 149 EP - 156 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-25924 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, A. A1 - Goecke, S.F. A1 - Rethmeier, Michael T1 - Laser beam oscillation welding for automotive applications N2 - Laser beam oscillation, applied one- or two-dimensional to the actual welding process, influences the welding process in terms of compensation of tolerances and reduction of process emissions like spatter and melt ejections that occur in industrial applications, such as in body-in-white manufacturing. If the welding process could be adapted to these tolerances by the momentarily demanded melt pool width to generate sufficient melt volume or to influence melt pool dynamics, e.g. for a better degassing, laser welding would become more robust. However, beam oscillation results are highly dependent on the natural frequency of the melt pool, the used spot diameter and the oscillation speed of the laser beam. The conducted investigations with an oscillated 300 μm laser spot show that oscillation strategies which are adjusted to the joining situation can bridge gaps to approximately 0.6 mm at metal sheet thickness of 0.8 mm. However, the complex behaviour of the melt pool has to be considered to generate proper welding results. This work puts emphasis on showing aspects of beam oscillation in fillet welding in lap joints. KW - Automotive application KW - Melt pool dynamics KW - Adaptive welding beam oscillation KW - Laser welding KW - Gap bridging PY - 2018 DO - https://doi.org/10.1007/s40194-018-0625-3 SN - 0043-2288 SN - 1878-6669 VL - 62 IS - 5 SP - 1039 EP - 1047 PB - Springer AN - OPUS4-45774 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - 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 - JOUR A1 - Häberle, Nicolas A1 - Pittner, Andreas A1 - Rethmeier, Michael A1 - Falkenberg, Rainer A1 - Kahlcke, Ole T1 - Application of multi-phase viscoplastic material modelling to computational welding mechanics of grade-s960ql steel N2 - The sound numerical prediction of welding-induced thermal stresses, residual stresses, and distortions strongly depends on the accurate description of a welded material’s thermomechanical deformation behaviour. In this work, we provide experimental data on the viscoplastic deformation behaviour of a grade-s960ql steel up to a temperature of 1000 ◦C. In addition, a multi-phase viscoplastic material model is proposed, which accounts for the experimentally observed isothermal deformation behaviour of grade-s960ql steel base and austenitised material, as well as for athermal contributions that originate from solid-state phase transformations. The multi-phase viscoplastic and a classic rateindependent isotropic hardening material model were applied in the numerical simulations of both-ends-fixed bar Satoh tests and a single-pass gas metal arc weld. The influence of material modelling choices on the agreement between numerical simulation and experimental results is discussed, and recommendations for further work are given. KW - Residual stress KW - Viscoplasticity KW - Material modeling KW - Grade S960QL steel PY - 2018 DO - https://doi.org/10.1016/j.crme.2018.08.001 VL - 346 IS - 11 SP - 1018 EP - 1032 PB - Elsevier Masson SAS AN - OPUS4-46512 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Üstündağ, Ö. A1 - Fritzsche, André A1 - Avilov, V. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Hybrid laser-arc welding of thick-walled ferromagnetic steels with electromagnetic weld pool support N2 - The hybrid laser-arc welding (HLAW) process provides many advantages over laser welding and arc welding alone, such as high welding speed, gap bridgeability, and deep penetration. The developments in hybrid laser-arc welding technology using modern high-power lasers allow single-pass welding of thick materials. This technology can be used for the heavy metal industries such as shipbuilding, power plant fabrication, and line-pipe manufacturing. The obvious problem for single-pass welding is the growth of the hydrostatic pressure with increasing thickness of materials leading to drop-out of molten metal. This phenomenon is aggravated at slow welding velocities because of increasing weld seam width followed by a decrease of Laplace pressure compensating the hydrostatic pressure. Therefore, weld pool support is necessary by welding of thick materials with slow welding velocities. The innovative electromagnetic weld pool support system is contactless and has been used successfully for laser beam welding of aluminum alloys and austenitic and ferromagnetic steels. The support system is based on generating Lorentz forces within the weld pool. These are produced by an oscillating magnetic field orientated perpendicular to the welding direction. The electromagnetic weld pool support facilitates a decrease in the welding speed without a sagging and drop-out of the melt thus eliminating the limitations of weldable material thickness. KW - Hybrid laser-arc welding KW - Thick-walled steel KW - Electromagnetic weld pool support KW - Ferromagnetic steels KW - High-power laser beam PY - 2018 DO - https://doi.org/10.1007/s40194-018-0597-3 SN - 1878-6669 VL - 62 IS - 4 SP - 767 EP - 774 PB - Springer AN - OPUS4-46825 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Marko, A. A1 - Raute, J. A1 - Linaschke, D. A1 - Graf, B. A1 - Rethmeier, Michael T1 - Porosity of LMD manufactured parts analyzed by Archmimedes method and CT N2 - Pores in additive manufactured metal parts occur due to different reasons and affect the part Quality negatively. Few investigations on the origins of porosity are available, especially for Ni-based super alloys. This paper presents a new study to examine the influence of common processing Parameters on the Formation of pores in parts built by laser metal Deposition using Inconel 718 powder. Further, a comparison between the computed tomography (CT) and the Archimedes method was made. The Investigation Shows that CT is able to identify different kinds of pores and to give further Information about their distribution. The identification of some pores as well as their shape can be dependent on the Parameter Setting of the Analysis tool. Due to limited measurement Resolution, CT is not able to identify correctly pores with Diameters smaller than 0.1 mm, which leads to a false decrease on Overall porosity. The applied Archimedes method is unable to differentiate between gas porosity and other Kinds of holes like internal cracks or lack of Fusion, but it delivered a proper value for Overall porosity. The method was able to provide suitable data for the statistical Evaluation with design of Experiments, which revealed significant Parameters ont he Formation of pores in LMD. KW - Laser metal deposition KW - Additive manufacturing KW - Density measurement KW - Porosity KW - Design of experiments PY - 2018 DO - https://doi.org/10.3139/120.111232 SN - 0025-5300 VL - 60 IS - 11 SP - 1055 EP - 1060 PB - Hanser CY - Berlin AN - OPUS4-47094 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bachmann, Marcel A1 - Avilov, Vjaceslav A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Fluid flow simulation of the influence of a steady magnetic field on the weld pool dynamics in deep penetration laser beam welding of aluminium N2 - A multi-physics numerical model was developed to investigate the influence of a steady magnetic field during partial penetration keyhole laser beam welding of an aluminum plate in flat position. Three-dimensional heat transfer, fluid dynamics including phase transition and electromagnetic field partial differential equations were solved with the finite element differential equation solver COMSOL Multiphysics. The magnetic field was aligned perpendicularly to the welding direction. The main objective of these simulations was to estimate the critical value of the magnetic field needed to suppress convective flows in the weld pool during high-power (up to 20 kW) laser beam welding of aluminum alloys with up to 20 mm deep weld pool. It reveals that steady magnetic fields with corresponding Hartmann numbers Ha^2 ~ 10^4 based on the half-width of the weld pool can effectively suppress convective flows in the weld pool. Moreover, the typically occurring wineglass-shape of the weld cross section caused by thermo-capillary flow is weakened. KW - Laser beam welding KW - Lorentz force KW - Marangoni stresses KW - Natural convection KW - Hartmann effect PY - 2012 SN - 1006-706X SN - 1001-0963 VL - 19 IS - Suppl. 1 SP - 467 EP - 470 PB - Ed. Board CY - Beijing AN - OPUS4-26914 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bachmann, Marcel A1 - Avilov, Vjaceslav A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Simulation of an inductive weld pool support for deep penetration laser beam welding of metal parts N2 - three-dimensional laminar steady state numerical model was used to investigate the influence of an altemating current (ac) magnetic field during single pass high power laser beam keyhole welding of 20 mm thick aluminum. The three-dimensional heat transfer, fluid dynamics and electromagnetic field equations were solved with the commercial finite element package COMSOL Multiphysics. Dominant physical effects of the process were taken into account: Thermo-capillary (Marangoni) convection at the upper and lower weld pool surfaces, natural convection due to the gravity influence and the latent heat of solid-liquid phase transition. Simulations were conducted for several magnetic field strengths and it was found that the gravity drop-out associated with welding of thick plates due to the hydrostatie pressure can be prevented by the application of an ac magnetic field below the weld specimen of around 70 mT (rms) at an oscillation frequency of 450 Hz. The inductive support System allows for single-pass laser beam welding of thick aluminum plates. The flow pattem in the molten zone and the temperature distributions are significantly changed by the application of the electromagnetic forces in the weld pool. KW - Electromagnetic weld pool support KW - Laser beam welding KW - Lorentz force KW - Marangoni stresses KW - Natural convection PY - 2012 SN - 1006-706X SN - 1001-0963 VL - 19 IS - Suppl. 1 SP - 114 EP - 117 PB - Ed. Board CY - Beijing AN - OPUS4-26913 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shcheglov, Pavel A1 - Gumenyuk, Andrey A1 - Gornushkin, Igor B. A1 - Rethmeier, Michael A1 - Petrovskiy, V.N. T1 - Vapor-plasma plume investigation during high-power fiber laser welding N2 - This work is devoted to the investigation of the laser–matter interaction during up to 20 kW ytterbium fiber laser welding of thick mild steel plates. The plume attenuation of a probe 1.3 µm wavelength diode laser beam as well as of continuous radiation in the 250–600 nm wavelength range was measured during welding with and without Ar shielding gas supply. The measured results allow the calculation of the average size and concentration of fine condensed metal particles in different plume areas using the multi-wavelength method and the Mie scattering theory. The plume temperature, which determines the condensation conditions, was measured by means of Fe I atom spectral line emission registration. The spatial distribution of the extinction coefficient in the welding plume was measured and the plume attenuation of the high-power fiber laser beam during the welding process was estimated. PY - 2013 DO - https://doi.org/10.1088/1054-660X/23/1/016001 SN - 1054-660X SN - 1531-8494 VL - 23 IS - 016001 SP - 1 EP - 7 PB - MAIK Nauka/Interperiodica Publ. CY - Moscow AN - OPUS4-27280 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gebhardt, Moritz Oliver A1 - Gumenyuk, Andrey A1 - Quiroz Penaranda, Vanessa A1 - Rethmeier, Michael T1 - Laser/GMA hybrid welding of thick-walled precision pipes N2 - Thick-walled pipes made of steel are the basis of a large number of components in mechanical and installation engineering, e.g. for hydraulic components, in power station technology or in the petroleum industry. Particularly when strict positional and shape tolerances are demanded, the classical manufacturing process is chip-producing machining from the solid material. However, this is time-intensive and material-intensive. The laser/GMA hybrid processes with modern high-power lasers are a suitable alternative. With these processes, it is currently possible to weld components with a wall thickness up to approx. 15 mm with little distortion in one pass. However, in initial experiments, solidification cracks with longitudinal and vertical orientations in relation to the welding direction, so-called central line cracks, were established in welds on pipes. Within the framework of a research project, it was possible to determine the cause of the cracking and to find measures in order to avoid it. The technical boundary conditions could be complied with in this respect. The article gives an overview of the research project and the essential results. PY - 2012 SN - 1612-3433 VL - 11 IS - 5 SP - 312 EP - 318 PB - DVS - German Welding Society CY - Düsseldorf AN - OPUS4-26912 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Albert, F. A1 - Baum, S. A1 - Goecke, S. A1 - Müller, A. A1 - Sievi, P. A1 - Rethmeier, Michael T1 - Nahtgeführtes Laserstrahl-Remoteschweißen mit Strahloszillation - Beeinflussung der Schweißnahtanmutung, der Schweißnahtgeometrie und der Spaltüberbrückbarkeit PY - 2013 SN - 0036-7184 VL - 65 IS - 9 SP - 631 EP - 635 PB - Verl. für Schweißen u. Verwandte Verfahren, DVS-Verl. CY - Düsseldorf AN - OPUS4-29300 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Graf, B. A1 - Ammer, S. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Design of experiments for laser metal deposition in maintenance, repair and overhaul applications N2 - Modern and expensive parts lead to an increasing demand for maintenance, repair and overhaul (MRO) technologies. Instead of part replacement, MRO technologies are economically advantageous throughout the life cycle. Laser metal deposition as modern MRO technology can be used to repair cracks or protect damaged surfaces with a hard facing layer. It is necessary to adjust weld bead profile to the specific task. For this purpose, Design of Experiment (DoE) has a high potential to decrease experimental effort. In this paper, a full factorial design is used to determine the effect of process parameters on the geometric dimensions of the weld bead. The paper is of interest to engineers working with laser metal deposition as well as DoE methods. T2 - 2nd International Through-life Engineering Services Conference CY - Cranfield, UK DA - 05.11.2013 KW - Design of experiments KW - Laser metal deposition KW - Laser powder cladding KW - Repair welding KW - MRO PY - 2013 DO - https://doi.org/10.1016/j.procir.2013.07.031 SN - 2212-8271 VL - 11 SP - 245 EP - 248 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-29339 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bachmann, Marcel A1 - Avilov, Vjaceslav A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Magnets improve quality of high-power laser beam welding N2 - Welding is one of the most critical industrial processes, essential for building reliable metal structures in everything from ships to reactor vessels. When welds fail, often the entire structure fails, and expectations on weid quality have never been higher. Any process that uses a localized heat source, such as welding, is likely to result in some distortion. The welding process of very thick metal components is not inherently stähle and is barely controllable without external forces. KW - Laser beam welding KW - Hartmann effect KW - Marangoni flow PY - 2013 UR - http://weldingdesign.com/processes/magnets-improve-quality-high-power-laser-beam-welding SN - 0043-2253 SP - 1 EP - 3 PB - Penton/IPC CY - Cleveland, Ohio AN - OPUS4-29412 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 - Müller, A. A1 - Goecke, S.F. A1 - Rethmeier, Michael T1 - Laser beam oscillation for fillet welding N2 - In today’s automotive frame-and-body construction, laser welds are typically carried out as square butt welds in lap joints. These welds are increasingly produced by remote laser welding optics with working distances of 500 mm and more. This enables simple path programming because clamping devices are traversed over and therefore low cycle times with improved productivity is achieved. However, workpiece tolerances lead to part displacements and varying joint positions over time. These displacements have to be acted against by appropriate flange length that contain for positioning deviations. Using this concept, aspired light-weight optimisations, e.g. reducing flange length, are difficult to achieve. By using seam tracking sensors, part tolerances are automatically detected and counteracted for. In addition, joint edge detection allows constructive changes on the type of weld. Fillet welds reduce flange lengths', improve force flow and open up possibilities for visual quality monitoring. Apart from that, vertical displacements in the form of height tolerances still occur. This needs consideration by adapting the set of welding parameter to the current welding situation. In this respect, one main welding parameter is the lateral beam offset to the upper sheet. Since body-in-white welding applications mainly comprise of zinc-coated steel sheets, special requirements for the welding process are given. Especially zero-gap-welding and welding of joints with gaps larger than 0.2 mm are critical. Using a laser beam oscillation process can stabilise these situations. Approaches to finding parameter sets are presented in this paper. KW - Laser beams KW - Welding KW - Fillet welds KW - Gap KW - Process procedures KW - Monitoring systems PY - 2014 DO - https://doi.org/10.1007/s40194-014-0165-4 SN - 0043-2288 SN - 1878-6669 VL - 58 IS - 6 SP - 865 EP - 872 PB - Springer CY - Oxford AN - OPUS4-32075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Su, H. A1 - Wu, Chuan Song A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Numerical modeling for the effect of pin profiles on thermal and material flow characteristics in friction stir welding N2 - Understanding the influence of tool/pin shapes on the thermal and material flow behaviors in friction stir welding is of great significance for the optimal design of tool/pin based on a scientific principle. In this study, a numerical method based on computational fluid dynamics is employed to quantitatively analyze the thermo-physical phenomena in friction stir welding with two tools of different pin shapes (axisymmetrical conical tool and asymmetrical triflat tool). Through combining a steady state model with a transient state model, both the computation efficiency and accuracy are ensured. The boundary conditions of heat transfer and material flow are determined with considering a partial sticking/sliding contact condition at the tool–workpiece interface. The total heat generation, heat density and temperature distribution during the welding process with triflat tool are elucidated and compared with that of conical tool, and the material flow patterns and deformation regions of various pin orientations are illustrated in detail. It is found that the deformation zone caused by triflat tool is larger than that by conical tool, which is validated by the weld macrographs. The computed thermal cycles and peak temperature values at some locations are in good agreement with the experimentally measured ones. KW - Friction stir welding KW - Pin profile KW - Heat generation KW - Material flow KW - Modeling PY - 2015 DO - https://doi.org/10.1016/j.matdes.2015.04.012 SN - 0261-3069 SN - 0264-1275 VL - 77 SP - 114 EP - 125 PB - Elsevier Ltd. CY - Oxford AN - OPUS4-33031 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ebert-Spiegel, M. A1 - Goecke, S.-F. A1 - Rethmeier, Michael T1 - Possibilities for compensating a higher heat input, in particular by the torch offset relative to the top sheet at the fillet weld on a lap joint N2 - This paper deals with the use of an adaptive control system for compensating the variation in the gap height of a fillet welded lap joint. Gap bridging requires the input of additional filler material and is related to an increased energy input. Hence, the aim was a compensation of the effect of an increased heat input, in order to maintain the weld pool and excessive penetration, which can prevent consequently root reinforcement and burn-through. The findings achieved in this work show possibilities for a real-time controlled adjustments of the welding parameters in automated metal active gas (MAG) welding for compensating a higher heat input, in particular by means of the torch offset relative to the top sheet at the fillet weld on a lap joint. KW - MAG welding KW - Adaptive control KW - High strength steels KW - Gap KW - Energy input KW - Mathematical models PY - 2015 DO - https://doi.org/10.1007/s40194-015-0220-9 SN - 0043-2288 SN - 1878-6669 VL - 59 IS - 3 SP - 443 EP - 453 PB - Springer CY - Oxford AN - OPUS4-33079 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thater, Raphael A1 - Wiethop, P. A1 - Rethmeier, Michael T1 - Welding simulation in car body construction N2 - Laser remote welding is a dynamic and flexible joining technology which enables various new approaches in welding sequence and weld position planning. However, the challenge is to find the optimal set-up within this large parameter space. In this article, numerical welding simulation is used to deal with this challenge. For a car door, different welding sequences and weld positions were numerically analyzed and compared with respect to its welding distortion behavior. PY - 2015 DO - https://doi.org/10.1002/latj.201500009 SN - 1613-7728 SN - 1863-9119 VL - 12 IS - 2 SP - 33 EP - 37 PB - Wiley-VCH CY - Weinheim AN - OPUS4-33110 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bachmann, Marcel A1 - Avilov, Vjaceslav A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Magnets improve quality of high-power laser beam welding N2 - Welding is one of the most critical operations for the construction of reliable metal structures in everything from ships to reactor vessels. When welds fail, the entire structure often fails—so expectations on weld quality have never been higher. Any process that uses a localized heat source, such as welding, is likely to result in some distortion. The welding process of very thick metal components is not inherently stable and is barely controllable without external forces. KW - Laser beam welding KW - Hartmann effect KW - Electromagnetic weld control KW - Finite element simulation PY - 2015 UR - http://digital.industrial-lasers.com/industriallasers/20150304#pg1 SN - 1523-4266 SN - 0888-935X VL - 30/2 IS - March/April SP - 10 EP - 12 PB - Pennwell CY - Tulsa, Okla., USA AN - OPUS4-33037 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schaumann, P. A1 - Schürmann, K. A1 - Dänekas, C. A1 - Rethmeier, Michael A1 - Schippereit, Christian A1 - Pittner, Andreas T1 - Automatisierte Fertigung von Hohlprofilknoten für Jacket-Gründungsstrukturen T1 - Automated manufacturing of tubular joints for jacket support structures - Description of the welding process chain as well as integration of the process parameters within the fatigue design N2 - The development within the offshore wind energy 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 support structures. Besides XL-monopiles the jacket support structure is a reasonable alternative due to the high rigidity combined with low material consumption. However, the effort for manufacturing of the hollow section joints reduces the economic potential of jacket structures significantly. Therefore, a changeover from an individual towards a serial production based on automated manufactured tubular joints combined with standardized pipes must be achieved. Hence, this paper addresses the welding process chain of automated manufactured tubular joints including digitization of the relevant manufacturing parameters such as laser scanning of the weld seam geometry. Additionally, a methodology for the computation of the notch radius as well as the weld seam angle is presented based on the scanned profiles of three analysis points of an automated manufactured tubular X-joint. Subsequently, these parameters are considered within the notch stress approach based fatigue design and their impact is quantified by a comparison with the structural stress approach using equivalent stress concentration factors. KW - Hohlprofilknoten KW - Tubular joints KW - Automatisierte Fertigung KW - Digitalisierung KW - Schweißnahtgeometrie KW - Kerbspannungskonzept KW - Äquivalente Spannungskonzentrationsfaktoren KW - Automated manufacturing KW - Digitization KW - Weld seam geometry KW - Notch stress approach KW - Equivalent stress concentration factors PY - 2018 DO - https://doi.org/10.1002/stab.201810017 SN - 0038-9145 SN - 1437-1049 VL - 87 IS - 9 SP - 897 EP - 909 PB - Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG CY - Berlin AN - OPUS4-46633 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - El-Batahgy, A.M. A1 - Gumenyuk, Andrey A1 - Gook, S. A1 - Rethmeier, Michael T1 - Comparison between GTA and laser beam welding of 9%Ni steel for critical cryogenic applications N2 - IncomparisonwithGTAweldedjoints,highertensilestrengthcomparabletothatofthebasemetalwasobtained for laser beam welded joints due to fine martensitic microstructure. Impact fracture toughness values with much lower mismatching were obtained for laser beam welded joints due to similarity in the microstructures of its weld metal and HAZ. In this case, the lower impact fracture toughness obtained (1.37J/mm2) was much higher than that of the GTA welded joints (0.78J/mm2), which was very close to the specified minimum value (≥0.75J/mm2). In contrast to other research works, the overall tensile and impact properties are influenced not only by the fusion zone microstructure but also by the size of its hardened area as well as the degree of its mechanical mismatching, as a function of the welding process. A better combination of tensile strength and impact toughness of the concerned steel welded joints is assured by autogenous laser beam welding process. KW - Impact absorbed energy KW - 9%Ni steel KW - GTAW KW - Laser beam welding KW - Fusion zone size KW - Microstructure Tensile strength PY - 2018 DO - https://doi.org/10.1016/j.jmatprotec.2018.05.023 SN - 0924-0136 IS - 261 SP - 193 EP - 201 PB - Elsevier AN - OPUS4-45776 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karkhin, Victor A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Simulation of solidification during laser welding of thin plates T1 - Моделирование процесса кристаллизации при лазерной сварке пластин малой толщины N2 - It is proposed to model the experimentally observed weld pool boundary with superellipses (Lamé curves) and to find the unknown parameters of the curves using optimization methods. It has been shown experimentally that during laser welding of austenitic stainless steel with a thickness of 2 mm at a speed of 20 mm/s, the rear weld pool part has a shape close to triangular which can be accurately approximated by a superellipse. Analytical dependences of the trajectory and growth rate of the crystal and its cross-sectional area on the geometry of the rear weld pool part are obtained. KW - Laser beam welding KW - Plane crystalization KW - Mathematical modeling KW - Superellipse KW - Thin steel plates PY - 2023 DO - https://doi.org/10.34641/SP.2023.1061.4.033 VL - 4 SP - 28 EP - 33 AN - OPUS4-59649 LA - rus AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gook, S. A1 - Üstündag, Ömer A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Verfahren zum fehlerfreien Laserstrahl-MSG-Hybridschweißen geschlossener Rundnähte N2 - In diesem Beitrag werden Ergebnisse der Untersuchungen eines Verfahrens zum fehlerfreien Laserstrahl-MSG-Hybridschweißen von geschlossenen Rundnähten vorgestellt. Das Verfahren zielt auf die Vermeidung von Schweißnahtunregelmäßigkeiten im Überlappbereich einer hybridgeschweißten Rundnaht. Eine Strategie der Prozessführung beim Schließen der Rundnaht wurde entwickelt, mit der ein fehlerfreier Überlappbereich durch die Kontrolle der Erstarrungsbedingungen am Schweißnahtende erreicht wird. Die kontrollierte Wärmeführung wird durch eine Anpassung der Parameter von beiden beteiligten Schweißprozessen, dem Laserstrahl sowie dem Metallschutzgas (MSG)-Schweißprozess, realisiert. Experimentelle Untersuchungen wurden an 12 bis 15 mm dicken Rohrabschnitten durchgeführt. Der Einfluss von Prozessparametern wie der Veränderung des Abbildungsmaßstabs und der Defokussierung des Laserstrahls auf die Erstarrungsbedingungen am Ende der Rundnaht wurde untersucht, um eine optimale Strategie zum Herausführen der Prozessenergie zu finden. Im Rahmen der experimentellen Untersuchungen konnte gezeigt werden, dass eine Defokussierung des Laserstrahls im Bereich zwischen 60 mm und 100 mm über einen kurzen Auslaufbereich der Naht von etwa 15 mm zu einer deutlich besseren Nahtausbildung im Überlappbereich führt. Es konnte eine günstige kelchförmige Schweißnaht ohne eine Tendenz zur Rissbildung erzielt werden. Die Laseroptik mit motorisch angesteuertem Linsensystem ermöglichte dabei eine Vergrößerung des Laserstrahldurchmessers ohne eine Veränderung der Position des MSG-Lichtbogens relativ zur Bauteiloberfläche. KW - Hybrid welding KW - Laser beam welding KW - Pipe manufacturing KW - As-shielded arc welding KW - Weld defects PY - 2021 VL - 73 IS - 3 SP - 116 EP - 121 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-52365 LA - deu 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 - JOUR A1 - El-Batahgy, A. A1 - Saiyah, A. A1 - Khafagi, S. A1 - Gumenyuk, Andrey A1 - Gook, Sergej A1 - Rethmeier, Michael T1 - Shielded metal arc welding of 9%Ni steel using matching ferritic filler metal N2 - Motivated by the tensile strength loss of 9%Ni steel arc welded joints made using Ni-based austenitic filler metals, the feasibility of maintaining the tensile strength using matching ferritic filler metal has been demonstrated. In comparison with shielded metal arc welded joint made using Ni-based austenitic electrode ENiCrMo-6, higher tensile strength comparable to that of the base metal was obtained using matching ferritic electrode. Besides, sufficient impact toughness energies with much lower mismatch were obtained for weld metal and heat-affected zone. Welded joint with a lower mechanical mismatching is of considerable importance for achieving acceptable combination of tensile strength and impact toughness. A better combination of These mechanical properties is ensured by applying a post weld heat treatment. KW - 9%Ni steel KW - Ni-based austenitic welding electrode KW - Matching ferritic welding electrode KW - Mechanical properties KW - Mechanical mismatching KW - Microstructure KW - SMAW PY - 2020 DO - https://doi.org/10.1080/13621718.2020.1846936 VL - 26 IS - 2 SP - 116 EP - 122 PB - Taylor & Francis AN - OPUS4-52025 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Marko, A. A1 - Schafner, A. A1 - Raute, J. A1 - Rethmeier, Michael T1 - Relative density prognosis for directed energy deposition with the help of artificial neural networks N2 - Additive manufacturing, and therefore directed energy deposition, is gaining more and more interest from industrial users. However, quality assurance for the components produced is still a challenge. Machine learning, especially using artificial neuronal networks, is a potential method for ensuring a high-quality standard. Based on process Parameters and monitoring data, part quality can be predicted. A further advantage is the ability to constantly learn and adopt to slight process changes. First tests using artificial neural networks focus on the prediction of track geometry. The results show that even a small data set is enough to provide high accuracy in the predictions. In this work, an artificial neural network for the predictive analysis of relative density in laser powder cladding has been developed. A central composite experimental design is used to generate 19 data sets. Input variables are laser power, feed rate and powder mass flow. Cubes are built up where density is considered as a target value. Several neural networks are trained and evaluated with these data sets. Different topologies and initial weights are considered. The best network reaches a confidence level of around 90 % for the prediction of relative density based on the process parame� ters. Finally, the optimization of the generalization performance is investigated. To this purpose, methods of variation in error limit as well as cross-validation are applied. In this way, density is predictable by an artificial neural network with an accuracy of about 95 %. KW - Directed energy deposition KW - Artificial neural network PY - 2021 DO - https://doi.org/10.1515/mt-2020-0004 SN - 0025-5300 VL - 63 IS - 1 SP - 41 EP - 47 PB - DE Gruyter CY - Berlin AN - OPUS4-52690 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Ökologische Bilanzierung von Schmelzschweißverfahren unter Berücksichtigung vor- und nachgelagerter Prozessschritte N2 - Ein wesentliches Ziel der deutschen Industriepolitik besteht darin, Rahmenbedingungen zu schaffen, welche die Positionierung nachhaltiger Produkte und Prozesse innerhalb globaler Wertschöpfungsketten ermöglichen und ökoeffiziente Fertigungsprozesse langfristig sichern. In diesem Beitrag werden aktuelle Forschungsarbeiten zur Bewertung der Umweltwirkungen der schweißtechnischen Fertigungskette anhand ausgewählter Schmelzschweißverfahren unter Berücksichtigung vor- sowie nachgelagerter Fertigungsschritte dargestellt. Eine weit verbreitete und standardisierte Methode zur Abschätzung der Umweltwirkungen eines Produkts oder Prozesses ist die Ökobilanzierung. Hierbei stellen die Sachbilanzierung, das heißt die Ermittlung sämtlicher relevanter Energie- und Ressourcenverbräuche während der schweißtechnischen Fertigung, aufgrund des hohen Dokumentationsaufwands, sowie die Ableitung assoziierter Wirkkategorien das größte Hindernis für eine Etablierung und Akzeptanz der Ökobilanzierung in der Praxis dar. Gleichwohl wird seitens Unternehmen, welche als Zulieferer von OEM’s (engl.: original equipment manufacturer) agieren, die Dokumentation des fertigungsspezifischen CO2-Verbrauches gefordert. Ein weiterer Aspekt der Arbeiten beinhaltet Methoden zur automatisierten Erfassung von schweißtechnischen Produktionsdaten sowie deren Nachverfolgbarkeit. Anhand unterschiedlicher Schweißverfahren werden die aus den Produktionsdaten abgeleiteten Energie- und Ressourcenverbräuche automatisiert in die relevanten Umweltwirkungen überführt. Die analysierten Schweißprozesse umfassen dabei ein breites für kleine und mittlere Unternehmen (KMU) relevantes Spektrum. Durch die softwareseitige Bereitstellung der aufgestellten Umweltprofile ist der Anwender in der Lage, Schweißprozesse unter ökologischen Aspekten zu bewerten und die effizienteste Variante zu identifizieren. KW - Umweltschutz PY - 2021 VL - 73 IS - 5 SP - 276 EP - 282 PB - DVS Media GmbH AN - OPUS4-52842 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tölle, Florian A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael A1 - Backhaus, A. A1 - Olschok, S. A1 - Reisgen, U. T1 - Mechanische Entlastung zur Eigenspannungsreduzierung in Strahlschweißnähten durch Anwendung eines defokussierten Strahls - Teil 1: Spannungsabbaumechanismus an linearen Strahlschweißnähten N2 - Schweißzugeigenspannungen in Strahlschweißnähten auf Höhe der lokalen Werkstoffstreckgrenze können die Bauteileigenschaften sowie deren Lebensdauer beeinflussen. Die Nutzung der Schweißquelle für eine nachträgliche Behandlung der geschweißten Bauteile bietet eine kostengünstige und flexible Methode zur Reduzierung dieser Spannungen. Dabei wird durch einen oszillierenden defokussierten Elektronen- bzw. Laserstrahl der Werkstoff beidseitig der Schweißnaht auf mehrere hundert Grad Celsius erwärmt, um dort zusätzliche Zugspannungsbereiche hervorzurufen. Die so erzeugten Längszugspannungszonen führen zu einer mechanischen Entlastung der Schweißnaht. Experimentelle Messungen zeigen, dass die Längseigenspannungen in der Schweißnaht mit diesem Verfahren um bis zu 70% reduziert werden können. Hierbei wurde neben der experimentellen Untersuchung dieses Verfahrens an Linearnähten an 5 mm dicken Blechen des Werkstoffs S355J2+N auch eine umfassende Analyse der Einflüsse der Verfahrensparameter auf die Spannungsreduktion mittels FEMSimulation durchgeführt. Anhand der Ergebnisse wird der Entlastungsmechanismus diskutiert. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Residual tensile welding stresses in beam welds at the level of the local yield strength of the material may influence the properties of components as well as their service lives. The utilisation of the welding source for the subsequent treatment of the welded components offers a cost-favourable and flexible method of reducing these stresses. In this respect, an oscillating defocused electron or laser beam serves to heat the material on both sides of the weld up to several hundred degrees Celsius in order to induce additional tensile stress regions there. The longitudinal tensile stress zones produced in this way lead to the mechanical relief of the weld. Experimental measurements show that the longitudinal residual stresses in the weld can be reduced by up to 70% with this process. In this case, not only was the experimental investigation into this process conducted on linear welds on 5 mm thick sheets made of the S355J2+N material but a comprehensive analysis of the influences of the process parameters on the stress reduction was also made by means of FEM simulation. The relief mechanism is discussed on the basis of the results. KW - Elektronenstrahlschweißen KW - Laserstrahlschweißen KW - Simulation und Berechnung KW - Spannungen KW - Wärmebehandlung KW - Electron beam welding KW - Laser welding KW - Simulation and calculation KW - Stresses KW - Heat treatment PY - 2012 SN - 0036-7184 VL - 64 IS - 6 SP - 332 EP - 340 PB - Verl. für Schweißen u. Verwandte Verfahren, DVS-Verl. CY - Düsseldorf AN - OPUS4-26340 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rethmeier, Michael A1 - Gumenyuk, Andrey A1 - Bachmann, Marcel T1 - High-power laser beam welding for thick section steels – new perspectives using electromagnetic systems N2 - In recent years, it was shown that the introduction of additional oscillating and permanent magnetic fields to laser beam and laser-arc hybrid welding can bring several beneficial effects. Examples are a contactless weld pool support for metals of high thickness suffering from severe drop-out when being welded conventionally or an enhanced stirring to improve the mixing of added filler material in the depth of the weld pool to guarantee homogeneous resulting mechanical properties of the weld. The latest research results show the applicability to various metal types over a wide range of thicknesses and welding conditions. The observations made were demonstrated in numerous experimental studies and a deep understanding of the interaction of the underlying physical mechanisms was extracted from numerical calculations. KW - Laser beam welding KW - Numerical simulations KW - Electromagnetic support PY - 2021 DO - https://doi.org/10.1080/13621718.2021.1999763 VL - 27 IS - 1 SP - 43 EP - 51 PB - Taylor & Francis Group AN - OPUS4-53970 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jokisch, T. A1 - Gook, S. A1 - Marko, A. A1 - Üstündag, Ömer A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Laserstrahlschweißen additiv gefertigter Bauteile: Einsetzbarkeit bestehender Bewertungsvorschriften N2 - Bei der additiven Fertigung im Pulverbett ist die Bauteilgröße durch den Bauraum begrenzt. Das Verbindungsschweißen additiv gefertigter Teile bietet eine Möglichkeit diese Größenbegrenzung aufzuheben. Aufgrund des spezifischen Spannungs- und Gefügezustands im additiv aufgebauten Teil ist jedoch unklar, inwiefern bestehende Bewertungsvorschriften des Verbindungsschweißens auch für Schweißnähte an additiv gefertigten Bauteilen geeignet sind. Dies wird anhand des Laserstrahlschweißens additiv gefertigter Rohrverbindungen untersucht. Die Schweißnähte werden mittels visueller Prüfung, metallografischer Untersuchungen sowie Computertomografie ausgewertet. Die festgestellten Fehlerarten sind vergleichbar zu konventionellen Bauteilen. Dies ist ein Indikator dafür, dass bestehende Bewertungsvorschriften die möglichen auftretenden Defekte auch für Schweißnähte an additiven Bauteilen abbilden. KW - Schweißunregelmäßigkeiten KW - Additive Fertigung KW - Laserstrahlschweißen KW - Schweißeignung PY - 2021 VL - 73 IS - 3 SP - 132 EP - 137 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-53575 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Raute, J. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Elektronenstrahl schweißt additiv gefertigte Nickel-Superlegierungen N2 - Die Additive Fertigung ist ideal zur Herstellung und Reparatur komplexer Bauteile aus hochfesten Werkstoffen. Doch es fehlen Fügeverfahren, die Heißrisse vermeiden. Die Lösung heißt Elektronenstrahl. KW - Additive Fertigung PY - 2021 SP - 1 EP - 6 AN - OPUS4-53979 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Raute, J. A1 - Jokisch, T. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Effects on crack formation of additive manufactured Inconel 939 sheets during electron beam welding N2 - The potential of additive manufacturing for processing precipitation hardened nickel-base superalloys, such as Inconel 939 is considerable, but in order to fully exploit this potential, fusion welding capabilities for additive parts need to be explored. Currently, it is uncertain how the different properties from the additive manufacturing process will affect the weldability of materials susceptible to hot cracking. Therefore, this work investigates the possibility of joining additively manufactured nickel-based superalloys using electron beam welding. In particular, the influence of process parameters on crack formation is investigated. In addition, hardness measurements are performed on cross-sections of the welds. It is shown that cracks at the seam head are enhanced by Welding speed and energy per unit length and correlate with the hardness of the weld metal. Cracking parallel to the weld area shows no clear dependence on the process variables that have been investigated, but is related to the hardness of the heat-affected zone. KW - Electron beam welding KW - Hot Cracks KW - Superalloy KW - Inconel 939 PY - 2021 DO - https://doi.org/10.1016/j.vacuum.2021.110649 SN - 0042-207X VL - 195 SP - 10649 PB - Elsevier Ltd. AN - OPUS4-53689 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Rethmeier, Michael A1 - Karkhin, V. A1 - Khomich, P. T1 - Modeling of hydrodynamic and thermal processes at laser welding with through penetration N2 - A mathematical model for physical processes in fusion welding has been developed. It is based on the equivalent heat source concept and consists of two parts: thermo-hydrodynamics of the weld pool and heat conduction in the weldment outside the pool. In thermo-hydrodynamic problem, temperature – dependent material properties, keyhole shape, thermo-capillary and natural convection, phase transformations and other physical phenomena are taken into consideration. Solution of the thermo-hydrodynamic problem by the finite element method is demonstrated with keyhole laser beam welding of a 15 mm thick steel plate. Thermo-capillary convection is primarily responsible for the intricate convex-concave melt pool shape and pool enlargement near the plate surfaces. The calculated and experimental molten pool dimensions are in close agreement. KW - Laser welding KW - Weld pool modeling KW - Heat conduction KW - Greens function method PY - 2021 DO - https://doi.org/10.1080/09507116.2021.1989209 SP - 1 EP - 12 PB - Taylor & Francis Group AN - OPUS4-54022 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - El-Sari, B. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Verbesserung der Vorhersagegüte von künstlichen neuronalen Netzen zum Widerstandspunktschweißen durch Auswertung des dynamischen Widerstands N2 - Das Widerstandspunktschweißen ist ein etabliertes Fügeverfahren in der Automobilindustrie. Es wird vor allem bei der Herstellung sicherheitsrelevanter Bauteile, zum Beispiel der Karosserie, eingesetzt. Daher ist eine kontinuierliche Prozessüberwachung unerlässlich, um die hohen Qualitätsanforderungen zu erfüllen. Künstliche neuronale Netzalgorithmen können zur Auswertung der Prozessparameter und -signale eingesetzt werden, um die individuelle Schweißpunktqualität zu gewährleisten. Die Vorhersagegenauigkeit solcher Algorithmen hängt von dem zur Verfügung gestellten Trainingsdatensatz ab. In diesem Beitrag wird untersucht, inwieweit die Vorhersagegüte eines künstlichen neuronalen Netzes durch Auswertung einer Prozessgröße, dem dynamischen Widerstand, verbessert werden kann. KW - Künstliche Intelligenz KW - Qualität KW - Neuronales Netz KW - Widerstandspunktschweißen PY - 2021 SP - 785 EP - 789 AN - OPUS4-53976 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 - 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 - Bachmann, Marcel A1 - Meng, Xiangmeng A1 - Artinov, Antoni A1 - Rethmeier, Michael T1 - Investigating defects caused by narrow pool shapes in deep penetration welding N2 - Laser beam welding is a widely used joining technique in many industrial applications. This is mainly due to its many unique advantages, especially compared to conventional arc welding processes. These advantages include, among others, highly concentrated energy deposition, low total heat input and a capacity to penetrate deep into the material while causing only small welding distortions. However, at the same time, the small dimension of the laser spot, high solidification rates, and small dimensions of the weld pool itself can provoke issues regarding the assembly tolerances of the workpiece, the hot-cracking phenomena, as well as keyhole-induced bubbles escaping from the melt. Weld pool shapes in laser beam welding are elongated at the external, free surfaces under the action of the main driving forces in the melt – such as recoil pressure and surface tension forces – while being shorter in the internal areas of the weld pool. This leads to a regular solidification sequence from the internal zones toward the free surfaces, e.g. from the bottom to the top in partial penetration welding. However, in recent studies reported in the literature and seen in the experimental and numerical investigations of BAM Bundesanstalt für Materialforschung und -prüfung in Berlin, it was found that an internal narrowing phenomenon can occur that is often accompanied by a distinct bulging of the weld bead in deeper zones. As the internal behaviour of the melt during the process is hardly optically accessible, several numerical models and experimental techniques were established to visualise the mechanisms of the formation of the bulging and the narrowing phenomenon and to reveal the consequences on the solidification sequence, pore formation, and filler metal dilution. KW - Weld pool shape KW - Laser beam welding KW - Solidification PY - 2022 SN - 1759-0752 IS - 57 SP - 28 EP - 29 PB - Europa Science CY - Cambridge, UK AN - OPUS4-56995 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kromm, Arne A1 - Brauser, Stephan A1 - Kannengießer, Thomas A1 - Rethmeier, Michael T1 - High-energy synchrotron diffraction study of a transformation induced plasticity steel during tensile deformation N2 - Energy-dispersive x-ray diffraction offers the possibility for measurement and evaluation of diffraction spectra containing information of various diffraction lines of all contributing crystalline phases of a material. Combined strain imaging and diffraction analysis was conducted during the tensile test of a low alloyed transformation-induced plasticity (TRIP) steel in order to investigate the transformation induced plasticity, strain hardening, and load partitioning effects. Optical strain imaging allowed for determination of localized true strains from three-dimensional deformations measured in situ. High-energy synchrotron radiation has permitted diffraction analysis in transmission mode to gather information from the material interior. Phase-specific stress evolution during loading could be observed applying the sin2ψ technique during certain load steps. The strains of the individual lattice planes were determined in different locations under varying angles between loading and perpendicular direction. Using energy-dispersive methods it was also possible to determine the transformation behaviour during elastic and plastic regime taking into account a large number of diffraction lines. The results show that the approach practised here enables one to pull together macroscopic and phase-specific microscopic material behaviour in order to improve existing models for prediction of complex load situations. KW - EDXRD KW - Transformation-induced plasticity (TRIP) KW - Residual stress KW - Synchrotron KW - Martensite transformation PY - 2011 DO - https://doi.org/10.1177/0309324711403969 SN - 0309-3247 SN - 2041-3130 VL - 46 IS - 7 SP - 581 EP - 591 PB - Sage CY - London AN - OPUS4-24604 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kannengießer, Thomas A1 - Rethmeier, Michael A1 - Portella, Pedro Dolabella A1 - Ewert, Uwe A1 - Redmer, Bernhard T1 - Assessment of hot cracking behaviour in welds N2 - Hot crack assessment during production and processing of metallic materials is an essential prerequisite for the safety of welded structures. The hot cracking investigations presented here were carried out as part of a study aimed at the development of Cr/Ni low transformation temperature filler materials. Low transformation temperature alloys open up the possibility for welding high strength steels. The externally loaded Modified Varestraint Transvarestraint hot cracking test was employed in the experiments described. The hot cracking resistance was evaluated with the help of light microscopy applied at the specimen surface. The proportionality between hot cracking susceptibility and Cr/Ni alloy content was explained by the altered solidification kinetics and by the enlarged solidification interval. The internal crack paths and the three-dimensional structure of the crack net in the material volume were examined using X-ray computer tomography. The total crack lengths for different material depths and circumjacent rectangular volumes, respectively, were be determined. An increasing hot cracking susceptibility with increasing Cr/Ni alloy content was also be established for the specimen volume. KW - Hot cracking KW - Low transformation temperature (LTT) alloy KW - Modified varestraint transvarestraint (MVT) hot cracking test KW - X-ray computer tomography PY - 2011 DO - https://doi.org/10.3139/146.110545 SN - 1862-5282 VL - 102 IS - 8 SP - 1001 EP - 1006 PB - Carl Hanser CY - München AN - OPUS4-24400 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Üstündag, Ömer A1 - Bakir, Nasim A1 - Brunner-Schwer, C. A1 - Knöfel, F. A1 - Gook, S. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Laserstrahlhybridschweissen von Türmen für Windkraftanlagen Ökonomische und ökologische Vorteile N2 - Das Laserstrahlhybridschweißen ist beim Schweißen von Türmen für Windkraftanlagen eine Alternative zum Unterpulverschweißen von Dickblechen in Mehrlagentechnik und bietet hier ökonomische und ökologische Vorteile. Der industrielle Einsatz des Verfahrens ist jedoch durch prozessspezifische Herausforderungen eingeschränkt. Die im Beitrag beschriebene kontaktlose elektromagnetische Badstütze dient zur Erweiterung des Verfahrenspotenzials im Dickblechbereich >15 mm. KW - Elektromagnetische Badstütze KW - Laserhybridschweißen KW - Windkraftanlagen KW - Ökonomische und ökologische Vorteile PY - 2022 VL - 7 SP - 340 EP - 347 PB - DVS Media GmbH AN - OPUS4-56372 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gook, Sergej A1 - El-sari, Bassel A1 - Biegler, Max A1 - Rethmeier, Michael T1 - Application of AI-based welding process monitoring for quality control in pipe production N2 - The paper presents the experimental results into the development of a multi-channel system for monitoring and quality assurance of the multi-wire submerged arc welding (SAW) process for the manufacture of large diameter pipes. Process signals such as welding current, arc voltage and the acoustic signal emitted from the weld zone are recorded and processed to provide information on the stability of the welding process. It was shown by the experiments that the acoustic pattern of the SAW process in a frequency range between 30 Hz and 2.5 kHz contains the most diagnostic information. The on-line quality assessment of the weld seam produced is carried out in combination with methods of artificial intelligence (AI). From the results obtained, it can be concluded that the use of the latest concepts in welding and automation technology, combined with the high potential of AI, can achieve a new level of quality assurance in pipe manufacturing. KW - Submerged arc welding KW - Artificial intelligence KW - High-strength fine-grain steels KW - Quality control PY - 2024 DO - https://doi.org/10.37434/tpwj2024.06.01 SN - 0957-798X IS - 6 SP - 3 EP - 8 PB - The Paton Publishing House AN - OPUS4-61000 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neumann, Benedikt A1 - Biegler, Max A1 - Goecke, Sven-Frithjof A1 - Rethmeier, Michael T1 - Detektion von Bindefehlern beim DED-Arc T1 - Detection of Lack of Fusion during DED-Arc N2 - Based on artificial intelligence (AI) developed for monitoring arc welding, this article presents a deep neural network for monitoring lack of fusion defects in wire arc additive manufacturing of aluminium. The aim is to detect defects in built-up volumes on the basis of weld source data. These can be successfully processed by the algorithm presented and a trained AI. The achieved accuracy of the network is 90 percent. N2 - In dem Beitrag wird aufbauend auf Machine-Learning-Modellen, welche bereits zum Überwachen des Schutzgasschweißen erforscht wurden, ein tiefes neuronales Netz (DNN) zum Monitoring beim DED-Arc von Aluminium vorgestellt. Ziel ist die Detektion von Bindefehlern in den aufgebauten Volumina auf Grundlage von in Echtzeit gemessenen Schweißstromquellensignalen. Es werden Merkmalsvariablen durch Vorverarbeitung extrahiert sowie die Korrelation zwischen den Merkmalsvariablen und den Defekten analysiert. Durch den vorgestellten Algorithmus werden diese automatisiert als Input an ein DNN übergeben. Das entwickelte und trainierte neuronale Netz erkennt anhand signifikanter Merkmale aus den Strom- und Spannungsdaten Bindefehler mit einer Genauigkeit von ca. 90 Prozent. KW - DED-Arc KW - Aluminiumschweißen KW - Bindefehler KW - Prozessüberwachung KW - Maschinelles Lernen KW - Deep Neural Network PY - 2024 DO - https://doi.org/10.1515/zwf-2024-1107 VL - 8 SP - 577 EP - 583 PB - Walter de Gruyter GmbH AN - OPUS4-61630 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Marquardt, R. A1 - Gook, S. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Handgeführtes Laserstrahlschweißen am T-Stoß eines niedrig legierten Stahls N2 - Das handgeführte Laserstrahlschweißen gewinnt in der Industrie zunehmend an Bedeutung, da die hohe Produktivität und die einfache Handhabung Unternehmen wirtschaftliche Vorteile bieten. Derzeit ist der Einsatz in der Industrie jedoch auf Teile mit ästhetischen Anforderungen beschränkt, die häufig aus hochlegiertem Stahl bestehen. Um das Handschweißen mit Laserstrahl auch für Bauteile aus kostengünstigen Stähle mit guten mechanischen Eigenschaften einsetzen zu können, untersucht diese Studie den Einfluss des Schutzgases auf die Porosität am mikrolegierten Stahl HX340LAD mit einer Dicke von 1,5 mm. Getestet wurden die Gase Argon, Stickstoff, CO2 sowie Mischungen aus Argon und CO2 an T-Stöße mit Zusatzdraht. Die Qualifizierung der Porosität erfolgte gemäß DIN EN ISO 13919-1 an Querschliffen als auch mittels Röntgenuntersuchung. Die Ergebnisse zeigen, dass für diesen Stahl die Bewertungsgruppe B mittels CO2 als Schutzgas erreicht werden kann. Stickstoff führt zu Gruppe C, Argon zu D. KW - Handgeführtes Laserstrahlschweißen KW - HHLW KW - Stahl KW - Laser PY - 2025 VL - 2025 IS - 06 SP - 44 EP - 47 PB - DVS Media AN - OPUS4-63345 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Huo, Wenjie A1 - Schmies, Lennart A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael A1 - Wolter, Katinka T1 - Prediction of mean strain from laser beam welding images and detection of defects via strain curves based on machine learning N2 - With the advancement of machine learning, many predictions and measurements in visual tasks can be achieved by convolutional neural networks (CNNs). Solidification hot cracking is a significant defect in laser beam welding, commonly encountered in practical applications. Existing theories indicate that the formation of cracks is closely related to strain accumulation near the solidification front. In this paper, we first leverage supervised Regression networks to design CNNs that achieve real-time average strain estimation for each frame in the collected welding videos. Two different architectures are proposed and compared: the first model stacks two frames at a set interval and feeds them into the network, while the second model extracts image features individually and predicts the results by calculating the correlation between them. Each network has its own advantages in Terms of computational efficiency and accuracy. Finally, we further train a multilayer perceptron (MLP) classification model that can detect the occurrence of cracks based on the predicted strain behaviors. KW - Laser beam welding KW - Mean strain prediction KW - Solidification cracking detection Convolutional neural networks KW - Convolutional neural networks PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-644495 DO - https://doi.org/10.1016/j.optlastec.2025.113975 SN - 0030-3992 VL - 192, Part F SP - 1 EP - 8 PB - Elsevier Ltd. AN - OPUS4-64449 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 - Chaurasia, Prashant Kumar A1 - Fabry, Çağtay A1 - Pittner, Andreas A1 - De, Amitava A1 - Rethmeier, Michael T1 - Automated in situ monitoring and analysis of process signatures and build profiles during wire arc directed energy deposition N2 - Wire arc directed energy deposition (DED-Arc) is an emerging metal additive manufacturing process to build near-net shaped metallic parts in a layer-by-layer with minimal material wastage. Automated in situ monitoring and fast-responsive analyses of process signatures and deposit profiles during DED-Arc are in ever demand to print dimensionally consistent parts and reduce post-deposition machining. A comprehensive experimental investigation is presented here involving real-time synchronous measurement of arc current, voltage, and the deposit profile using a novel multi-sensor monitoring framework integrated with the DED-Arc set-up. The recorded current–voltage transients are used to estimate the time-averaged arc power, and energy input in real time for an insight of the influence of wire feed rate and printing travel speed on the deposit characteristics. A unique attempt is made to represent the geometric profiles of the single-track deposits in a generalized mathematical form corresponding to a segmented ellipse, which has exhibited the minimum root-mean-square error of 0.03 mm. The dimensional inconsistency of multi-track deposits is evaluated quantitatively in terms of waviness using build profile monitoring and automated estimation, which is found to increase with an increase in step-over ratio and energy input. For the multi-track mild steel deposits, the suitable range of step-over ratio for the minimum surface waviness is observed to lie between 0.6 and 0.65. Collectively, the proposed framework of synchronized process monitoring and real-time analysis provides a pathway to achieve dimensionally consistent and defect-free parts, and highlights the potential for closed-loop control systems for a wider industrial application of DED-Arc. KW - Additive Manufacturing KW - Arc welding KW - DED-arc KW - Real-time monitoring and control KW - Dimensional inconsistency PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-642029 DO - https://doi.org/10.1007/s40964-025-01333-9 SN - 2363-9512 SP - 1 EP - 20 PB - Springer Science and Business Media LLC CY - Cham AN - OPUS4-64202 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - El-Sari, B. A1 - Biegler, M. A1 - Gook, S. A1 - Rethmeier, Michael T1 - KI zur Prozessüberwachung im Unterpulverschweißen N2 - Beim Unterpulverschweißen sind die Prozessgeräusche ein Indikator für eine gute Fügequalität. Diese Beurteilung kann i.d.R. nur von einer erfahrenen Fachkraft durchgeführt werden. Eine kürzlich entwickelte künstliche Intelligenz kann automatisch das akustische Prozesssignal anhand vortrainierter Merkmale klassifizieren und die Fügequalität anhand des Geräuschs beurteilen. Der Algorithmus, einmal richtig trainiert, kann den Prüfaufwand beim Unterpulverschweißen deutlich reduzieren. KW - Unterpulverschweißen KW - Künstliche Intelligenz KW - Prozessüberwachung KW - Körperschall PY - 2024 SP - 1 EP - 2 AN - OPUS4-59483 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Üstündag, Ömer A1 - Bakir, Nasim A1 - Gook, S. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Hybrid Laser-Arc Welding of Thick-Walled, Closed, Circumferential Pipe Welds N2 - The application of hybrid laser-arc welding (HLAW) for joining closed circumferential welds is a challenge due to the high risk of forming a defective overlap area with a shrinkage void or solidification cracks in the material thickness. A series of HLAW experiments were performed to understand the development of a faulty overlap area when closing the circumferential weld. Welding trials on flat specimens and pipe segments were supported by numerical analyses in which the thermomechanical behavior of the welds in the overlap area was investigated. Different process control strategies were tested, including variations in defocusing levels and the overlap length. The newly developed HLAW head, including laser optics with a motor-driven collimation system, made it possible to defocus the laser beam during welding without disturbing the stability of the welding process. High-level defocusing of the laser beam of more than 40 mm relative to the specimen surface with a resulting beam diameter of > 2.9 mm, and in combination with a short overlap length of 15 mm, was promising with respect to the formation of a desired cup-shaped weld profile that is resistant to solidification cracks. KW - Hybrid Laser-Arc Welding KW - Thick-Walled Steel KW - High-Power Welding KW - Crater KW - Pipe Welding PY - 2022 DO - https://doi.org/10.29391/2022.101.002 SN - 0043-2296 VL - 101 IS - 1 SP - 15 EP - 26 PB - American Welding Society CY - New York, NY AN - OPUS4-55508 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -