TY - GEN A1 - Walther, Dominik A1 - Schmidt, Leander A1 - Räth, Timo A1 - Schricker, Klaus A1 - Bergmann, Jean Pierre A1 - Sattler, Kai-Uwe A1 - Mäder, Patrick T1 - Deep learning-driven active sheet positioning using linear actuators in laser beam butt welding of thin steel sheets T2 - Journal of advanced joining processes N2 - Welding thin steel sheets in industrial applications is difficult because joint gaps occur during the process, which can lead to weld interruptions. Such welds are considered a reject and in order to avoid the weld to interrupt it is crucial to hinder the formation of joint gaps. Especially laser beam welding is affected by the emergence of gaps. Due to the narrow laser spot, product quality is highly dependent on the alignment and positioning of the sheets. This is typically done by clamping devices, which hold the workpieces in place. However, these clamps are suited for a specific workpiece geometry and require manual redesign every time the process changes. Adaptive clamping devices instead are designed to realize a time-dependent workpiece adjustment. Modeling the joint gap behavior to realize a controller for adaptive clamps can be difficult as the influence of heating, melting, and cooling on the joint gap formation is unknown and varies due to temperature dependent physical properties. Instead, the control parameters and actions can be derived using data-driven methods. In this paper, we present a novel data-driven approach how deep learning can be utilized to manipulate the sheet position during the weld with two actuators that apply force. A temporal convolution neural network (TCN) analyzes the change of the joint gap and predicts the required force to adapt the workpiece position. The developed method has been integrated into the welding process and improves the length of the average weld seam by 39.5% compared to welds without an active adjustment and 1.4% to welds that have been adapted with a constant force. KW - Laser beam welding KW - Temporal convolutional neural network KW - Thin steel sheets KW - Inductive probes KW - Gap adjustment KW - Deep learning Y1 - 2025 U6 - https://doi.org/10.1016/j.jajp.2025.100303 SN - 2666-3309 VL - 11 SP - 1 EP - 12 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Walther, Dominik A1 - Schmidt, Leander A1 - Schricker, Klaus A1 - Junger, Christina A1 - Bergmann, Jean Pierre A1 - Notni, Gunther A1 - Mäder, Patrick T1 - Dataset for weld seam analysis and discontinuity prediction in laser beam welding scenarios T2 - Data in brief N2 - Laser beam welding can produce narrow, high-quality welds in various industrial joining processes. The thermal expansion and contraction of the metal during the weld results in the displacement of the sheets. That leads to the formation of joint gaps and subsequent to a process interruption. This behavior has only been analyzed to a limited extent and causes manufacturers to rely on heavy clamping systems rather than using more flexible fixtureless approaches. Due to the time-consuming and costly nature of recording and producing erroneous weld seams, such recordings and datasets are rarely available in this area. This often limits the research towards adaptable fixtureless welding setups. Because of this, we present a multi-modal dataset consisting of 100 recorded welds that tracks the metal sheets movement. The developed setup enables the determination of boundary conditions for fixtureless welding. Two types of sensors record the welding process. First, three inductive probes are applied to record the metal sheets` movement and second, a long-wave infrared (LWIR) camera records changes in the thermal radiation field. Two different welding speeds and laser powers were used to produce a variety of welds. The dataset can be used for data-driven algorithms to predict the metal movement, analyze the thermal radiation field, or develop quality control methodologies. KW - Laser Beam Butt Welding KW - Inductive Probes KW - LWIR Camera KW - Time Series KW - Images KW - Thin Steel Sheets KW - Classification KW - Regression Y1 - 2025 U6 - https://doi.org/10.1016/j.dib.2025.111381 SN - 2352-3409 VL - 59 SP - 1 EP - 8 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Diegel, Christian A1 - Schricker, Klaus A1 - Schmidt, Leander A1 - Seibold, Marc A1 - Friedmann, Hannes A1 - Hellwig, Peter A1 - Fröhlich, Fabian A1 - Nagel, Falk A1 - Kallage, Peter A1 - Rack, Alexander A1 - Requardt, Herwig A1 - Chen, Yunhui A1 - Bergmann, Jean Pierre T1 - In situ characterization of keyhole behavior and spatter formation in full penetration laser beam welding with local gas flow using high-speed synchrotron X-ray imaging T2 - Optics & laser technology N2 - Spatter formation is a major issue at welding speeds above 8 m/min for full penetration laser beam welding of high-alloyed steels. In experiments using a local gas flow directed at the keyhole rear wall, a reduction in spatter formation on the specimen top side was observed for welding of AISI 304. However, the interaction between gas flow and keyhole behavior with respect to the mechanisms and locations of spatter detachment, especially on the bottom side, is not yet fully understood. High-speed synchrotron X-ray imaging enables detailed insights into the keyhole behavior and the spatter formation to obtain a deeper understanding of the underlying mechanisms. During the reference experiments welding without shielding gas flow, the spatter detach from a melt pool swelling behind the keyhole aperture on both sides of the sheet. A gas flow with a low flow rate of 4.8 L/min reduces the spatter formation on the top side and the keyhole length due to the absence of oxygen affecting the surface tension. A swelling also forms on the keyhole front on the bottom side and small spatter detach undirected. Increasing the flow rate to 12.8 L/min elongates the keyhole, particularly on the specimen top side. The increased momentum transfer of the gas flow results in a periodic keyhole oscillation on the specimen top side. In combination with an elongated melt pool, the oscillation is directly correlated with the hump formation, caused by melt being pushed over the already solidified weld seam. In addition, spatter does not detach from the top side due to the changed melt flow and only detach from the keyhole front on the bottom side. KW - Laser welding KW - Spatter formation KW - Gas flow KW - High-speed X-ray imaging KW - Synchrotron KW - In situ Y1 - 2025 U6 - https://doi.org/10.1016/j.optlastec.2025.113367 SN - 0030-3992 VL - 191 SP - 1 EP - 17 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Ermilova, E. A1 - Hlushkova, D.B. A1 - Volchuk, V.M. T1 - The effect of plasma coatings on the properties of low-alloy steels T2 - Functional materials N2 - The paper considers the possibility of using ion-plasma spraying of coatings on low-alloy steels 4Х5MFS and 5ХNM. The choice of these grades is due to the fact that they do not contain tungsten, given the sharp increase in its deficiency, and the molybdenum content is limited, and these steels also meet the requirements for the substrate material on which the titanium nitride coating is applied. The coatings were applied by the method of condensation of the substance under ion bombardment conditions. To determine the required nitrogen pressure, titanium nitride is applied at different partial nitrogen pressures – from 310 -3 to 1 Pa. Coatings obtained under different nitrogen pressures differ in the amount and size of the droplet phase. The largest amount of the droplet phase containing α-Ti is observed in coatings obtained at nitrogen pressures of 3x10–3 Pa, 3x10–2 Pa. An increase in nitrogen pressure (4·10–1 Pa, 1 Pa) significantly reduces the level of microdistortions of crystal lattices in the coating, its plasticity increases. In this regard, the fragility of the coating decreases with its sufficiently high hardness. As laboratory tests have shown, a titanium nitride coating applied under optimal technological parameters increases the corrosion resistance of the materials on which it is applied three times, and scale resistance – two to four times. KW - Ion-plasma coatings KW - Surface KW - Phase KW - Strengthening KW - Parameters Y1 - 2025 U6 - https://doi.org/10.15407/fm32.01.50 SN - 1027-5495 SN - 2218-2993 VL - 32 IS - 1 SP - 50 EP - 55 PB - National Academy of Sciences of Ukraine (Co. LTD Ukrinformnauka) (Publications) CY - Charkiw ER - TY - GEN A1 - Nikitin, A. A1 - Hlushkova, D.B. A1 - Volchuk, V.M. A1 - Ragulin, V.M. T1 - Multifractal approach to assessing the heterogeneity of carbon alloys T2 - Functional materials N2 - A multifractal structural analysis of carbon alloy structures after multi-stage flow processing was carried out. The statistical dimensions of the D-300 structure varied from 4.18 to 2.47, indicating the compactness of filling the space with martensite, bainite and pearlite. Indicators of the statistical dimension of cementite in the range from 2.18 to 1.55 characterize the dimension of the D300 structure. The fractal D0, information D1, correlation D2 dimensions of martensite, bainite, pearlite also varied in the range from 2.66 to 2.13, indicating the heterogeneity of the structure. A one-to-one correspondence between the multifractal indicators of the structure and the hardness of the iron-carbon alloy was established. KW - Carbon alloys KW - Multifractal KW - Structure KW - Hardness KW - Statistical dimensions KW - Orderliness KW - Regularity Y1 - 2025 U6 - https://doi.org/10.15407/fm32.01.161 SN - 1027-5495 SN - 2218-2993 VL - 32 IS - 1 SP - 161 EP - 165 PB - National Academy of Sciences of Ukraine (Co. LTD Ukrinformnauka) (Publications) CY - Charkiw ER - TY - GEN A1 - Morozova, Iuliia A1 - Obrosov, Aleksei A1 - Naumov, Anton A1 - Michailov, Vesselin A1 - Doynov, Nikolay ED - Markopoulos, Angelos P. ED - Astolfi, Davide T1 - Factors affecting mechanical properties of impulse friction stir welded AA2024-T351 under static and cyclic loads T2 - Machines N2 - This study investigates the factors affecting the mechanical performance of conventional and impulse friction stir welded (FSW and IFSW) AA2024-T351 joints under static and cyclic loading. Emphasis is placed on the influence of fracture-inducing features such as oxide inclusions, constituent particle distributions, crystallographic texture, and precipitation state. A series of IFSW welds produced at varying impulse parameters were compared to conventional FSW welds in terms of microhardness, tensile strength, fatigue life, and Taylor factor distribution. IFSW joints demonstrated a significant improvement in tensile strength and elongation, particularly at higher impulse frequencies. Enhanced material mixing due to the reciprocating tool motion in IFSW resulted in finer particle distribution, more favorable crystallographic texture, and reduced weld pitch, all contributing to increased ductility and strength. Fractographic analyses revealed that fatigue failures primarily initiated in the stir zone, typically at unplasticized metallic inclusions. However, IFSW joints displayed longer fatigue lives, particularly when impulse parameters were optimized. These findings underline the complex interplay of microstructural and textural factors in determining weld performance, highlighting IFSW as a promising technique for enhancing the durability of high-strength aluminum welds. KW - Friction stir welding KW - Al alloy AA2024 KW - Fracture KW - Taylor factor KW - Intermetallic bands Y1 - 2025 U6 - https://doi.org/10.3390/machines13060529 SN - 2075-1702 VL - 13 IS - 6 SP - 1 EP - 16 PB - MDPI CY - Basel ER - TY - GEN A1 - Schricker, Klaus A1 - Schmidt, Leander A1 - Nagel, Falk A1 - Diegel, Christian A1 - Friedmann, Hannes A1 - Seibold, Marc A1 - Hellwig, Peter A1 - Fröhlich, Fabian A1 - Kallage, Peter A1 - Chen, Yunhui A1 - Requardt, Herwig A1 - Rack, Alexander A1 - Bergmann, Jean Pierre T1 - A comprehensive study on the influence of spatial power distribution on time-dependent keyhole behavior in laser beam welding of copper by means of high-speed synchrotron X-ray imaging T2 - Optics & laser technology N2 - This paper examines the impact of spatial power distributions on the time-dependent keyhole behavior during laser beam welding of copper using high-speed synchrotron X-ray imaging. The experimental setup utilized a COHERENT HighLight FL8000-ARM fiber laser with concentric intensity distribution created by an optical fiber cable. The European Synchrotron Radiation Facility (ESRF, beamline ID19) was used to conduct high-speed synchrotron imaging at 20,000 images per second to study the spatio-temporal keyhole behavior. Keyhole geometries were extracted through advanced image processing techniques, allowing quantification of parameters like depth, aperture, bulging, and determination of related oscillation frequencies. The results showed that core-dominated processes exhibit significant variations in keyhole geometry. In contrast, ring-dominated processes exhibited reduced penetration depths but increased melt pool dynamics due to altered absorption conditions and increased temperatures within the melt pool. A stabilized core-ring power distribution minimized fluctuations, resulting in improved process stability. The findings were summarized in a model concept describing three characteristic keyhole regimes: core-dominated, ring-dominated, and stabilized core-ring processes. KW - Laser welding KW - Synchrotron KW - In situ KW - Copper KW - Intensity, spatial power distribution Y1 - 2025 U6 - https://doi.org/10.1016/j.optlastec.2025.113999 SN - 0030-3992 VL - 192, Part E SP - 1 EP - 15 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Kotlarski, Georgi A1 - Ormanova, Maria A1 - Nikitin, Alexander A1 - Parasar, Ashirwad A1 - Ossenbrink, Ralf A1 - Doynov, Nikolay A1 - Valkov, Stefan A1 - Michailov, Vesselin T1 - Wire arc deposition of specimens using a special-designed aluminum-cored wire with CNTs T2 - Journal of physics : conference series N2 - This work investigated the possibility of manufacturing components using an aluminum welding wire with an aluminum powder core reinforced with carbon nanotubes (CNTs). Appropriate technological conditions of deposition were selected for the successful manufacturing of a wall-shaped specimen. The last was built using a multi-track approach. The results indicated the presence of a large quantity of pores within the volume of the specimen with values of over 30%. Regardless of the high defect quantity within the specimen a number of successfully integrated carbon nanoparticles were detected in certain areas of the cross-section of the specimen in the form of an Al₄C₃ composite. Y1 - 2025 U6 - https://doi.org/10.1088/1742-6596/2994/1/012024 SN - 1742-6588 SN - 1742-6596 VL - 2994 IS - 1 SP - 1 EP - 6 PB - IOP Publishing CY - Bristol ER - TY - GEN A1 - Zaiß, Felix A1 - Powell, John A1 - Haas, Michael A1 - Wahl, Johannes A1 - Diegel, Christian A1 - Schricker, Klaus A1 - Bergmann, Jean Pierre A1 - Hummel, Marc A1 - Spurk, Christoph A1 - Olowinsky, Alexander A1 - Beckmann, Felix A1 - Moosmann, Julian A1 - Hagenlocher, Christian A1 - Graf, Thomas T1 - The influence of different core-ring intensity distributions on the capillary shape and resulting weld in laser welding of steel T2 - Optics & laser technology N2 - Laser welding was carried out using a co-axial core-ring beam, with independent control of the power to the core and the ring. The welding process was observed using high-power X-rays and high-speed imaging equipment. Adjusting the relative powers of the core and the ring beams was found to have profound effects on the shape of both the capillary created and the weld melt pool. Moderate laser power densities in the ring were found to increase the top diameter of the weld pool and reduce fluctuations in the welding process. High laser power densities in the ring led to the creation of a second capillary which largely acted independently of the capillary generated by the laser power in the core. At high power densities and welding speeds the two capillaries were almost completely separated in the direction of travel. KW - Laser welding KW - Capillary KW - Weld seam KW - High-speed synchrotron KW - X-ray imaging KW - Beam shaping KW - Multi-core fiber system KW - Spatter formation KW - High-speed imaging Y1 - 2026 U6 - https://doi.org/10.1016/j.optlastec.2025.114495 SN - 0030-3992 VL - 194 SP - 1 EP - 12 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Zaiß, Felix A1 - Powell, John A1 - Haas, Michael A1 - Diegel, Christian A1 - Schricker, Klaus A1 - Bergmann, Jean Pierre A1 - Spurk, Christoph A1 - Hummel, Marc A1 - Olowinsky, Alexander A1 - Beckmann, Felix A1 - Moosmann, Julian A1 - Hagenlocher, Christian A1 - Graf, Thomas T1 - Core-ring laser welding : the influence of ring diameter on the capillary dynamics and the formation of pores in the resulting weld T2 - Lasers in manufacturing and materials processing N2 - Double-core fibers that deliver laser beams with adjustable amounts of power to the central core and the surrounding ring component of the fiber are of major interest for optimizing laser welding processes. However, the central focussed laser spot and the ring diameters are fixed by the fiber dimensions, the focusing optics, and the laser systems involved. This work investigates the influence of different ring beam diameters, with a constant central spot diameter, on the capillary dynamics and the formation of pores in the resulting welds in 1.4301 stainless steel (X5CrNi18-10, AISI 304). The different core-ring configurations were achieved using specially designed beam-shaping optics. The generation of pores during the welding process was examined by means of synchrotron X-ray imaging. The results show that different ring diameters have a profound effect on the melt pool geometry, the capillary shape and the location of the capillary collapse which gives rise to pore formation in the weld. In the examples presented here, larger ring diameters extended the melt pool in the direction of welding without contributing directly to the capillary evaporation. In this case the narrow, deep capillaries which are created by the core beam alone can bulge and collapse, trapping vapor and gas to create large pores. If, however, the ring beam has a small enough diameter, it can help to produce a wider capillary which does not trap gas and create pores in the same way. The mechanisms by which large bubbles in the melt can result in non-spherical pores in the weld are also explained. KW - Core-ring laser welding KW - Pore formation KW - Synchrotron x-ray imaging KW - Stainless steel KW - Multicore fiber system KW - Keyhole dynamics Y1 - 2026 U6 - https://doi.org/10.1007/s40516-026-00331-1 SN - 2196-7229 PB - Springer Science and Business Media LLC CY - New York, NY ER -