TY - JOUR A1 - Üstündag, Ömer A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Influence of an external applied AC magnetic field on the melt pool dynamics at high-power laser beam welding JF - IOP Conference Series: Materials Science and Engineering N2 - The study deals with the determination of the influence of an externally applied oscillating magnetic field on the melt pool dynamics in high power laser beam and hybrid laser arc welding processes. An AC magnet was positioned under the workpiece which is generating an upward directed electromagnetic force to counteract the formation of the droplets. To visualise the melt flow characteristics, several experiments were carried out using a special technique with mild steel from S355J2 with a plate thickness of up to 20 mm and a quartz glass in butt configuration. The profile of the keyhole and the melt flow were recorded with a highspeed camera from the glass side. Additionally, the influence of the magnetic field orientation to the welding direction on the filler material dilution on laser hybrid welding was studied with variating oscillation frequency. The element distribution over the whole seam thickness was measured with X-ray fluorescence (XRF). The oscillation frequency demonstrated a great influence on the melt pool dynamics and the mixing of the elements of the filler wire. The highspeed recordings showed, under the influence of the magnetic field, that the melt is affected under strong vortex at the weld root, which also avoids the formation of droplets. T2 - 18th Nordic Laser Materials Processing Conference (18th NOLAMP) KW - Laser beam welding KW - AC magnetic field KW - Melt pool dynamics KW - Filler wire mixing PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-539231 DO - https://doi.org/10.1088/1757-899X/1135/1/012017 VL - 1135 IS - 012017 SP - 1 EP - 10 PB - IOP Publishing AN - OPUS4-53923 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Üstündag, Ömer A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Influence of oscillating magnetic field on the keyhole stability in deep penetration laser beam welding JF - Optics and Laser Technology N2 - The stability of the keyhole decreases for deep penetrated high-power laser beam welding. The keyhole tends to collapse with increasing laser power and e.g. keyhole induced porosity can occur. This study deals with the observation of the keyhole during high-power laser beam welding in partial penetration mode by means of a high-speed camera. A butt configuration of 25 mm thick structural steel and transparent quartz glass was used for the experiments. An oscillating magnetic field was applied perpendicular to the welding direction on the root side of the steel plate. The keyhole was highlighted with a coaxial diode laser. It was ascertained that the stability of the keyhole and the weld penetration depth were increased by applying an oscillating magnetic field with an oscillating frequency of 1.2 kHz and a magnetic flux density of 50 mT. KW - Magnetic field KW - Laser beam welding KW - Keyhole stability PY - 2021 DO - https://doi.org/10.1016/j.optlastec.2020.106715 SN - 0030-3992 VL - 135 SP - 106715 PB - Elsevier Ltd. AN - OPUS4-52007 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Straße, Anne A1 - Üstündag, Ömer A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael ED - Schmidt, M. ED - Vollertsen, F. ED - Govekar, E. T1 - LMD coatings as filler material for laser beam welded 30 mm thick plates T2 - Procedia CIRP N2 - The development of high energy laser sources enables single-pass welds of thick plates up to 30 mm, but often additional materials are needed to influence the properties of the weld seams. However, the homogenous distribution of filler materials in form of e.g. electrodes is only possible up to 7 mm while the elements are only traceable up to a depth of 14 mm. To overcome this problem a two-step process is used where first the edges of the weld partners are coated with the filler material by laser metal deposition (LMD) and afterwards are welded by laser beam. Single-pass welds with electromagnetic weld pool support of 30 mm thick S355 J2+N-plates with austenitic AISI 316L-coatings were investigated as well as the influence of the coatings to the penetration depth of the laser beam without electromagnetic weld pool support in double-sided joints. The weld seams were tested by X-ray inspection and cross sections. T2 - 11th CIRP Conference on Photonic Technologies [LANE 2020] CY - Online meeting DA - 07.09.2020 KW - Penetration depth KW - Laser metal deposition (LMD) KW - Laser beam welding KW - Filler material distribution PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-512790 DO - https://doi.org/10.1016/j.procir.2020.09.055 SN - 2212-8271 VL - 94 SP - 293 EP - 297 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-51279 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Straße, Anne A1 - Rethmeier, Michael A1 - Gumenyuk, Andrey T1 - Influence of edge‑deposited layers on mechanical and corrosion properties of laser beam welds of 15 mm thick AISI 2205 duplex stainless steel JF - Welding in the World N2 - AISI 2205 duplex stainless steel is used in a variety of industries, including the chemical and petrochemical industries. This is due to its high tensile strength combined with good ductility and corrosion resistance. However, in laser beam welding, these properties are negatively afected by the high cooling rates typical of the welding process. The resulting higher ferrrite content in the weld metal than in the base material leads to a reduction in the ductility and corrosion resistance of the welded joint. To overcome this problem, in this study, thick plates were coated by direct energy deposition (DED) prior to laser beam welding, whereas a duplex powder mixture containing a higher nickel concentration was used as a coating material. To improve the weld quality for the proposed two-step process, a method of additional material deposition instead of conventional tack weld was investigated. The resulting welded joints showed a well-balanced austenite to ferrite ratio and their properties and microstructure were verifed by metallographic analysis, electron backscatter difraction and Charpy impact testing. Using the standard ASTM G48 test method, it was found that the corrosion resistance of the welds was improved by a factor of four in average compared to the conventionally welded joints. The resulting properties, such as good ductility and corrosion resistance, of the welds with pre-coated edges showed good agreement with those of the base metal and confrmed the proposed two-step process as a promising alternative to the conventional approaches for welding thick duplex stainless steel plates. KW - Laser metal deposition KW - Laser beam welding KW - Duplex steels PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-581731 UR - https://rdcu.be/dlb6E DO - https://doi.org/10.1007/s40194-023-01567-7 SN - 0043-2288 SP - 1 EP - 12 PB - Springer AN - OPUS4-58173 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Straße, Anne A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Study on Duplex Stainless Steel Powder Compositions for the Coating of thick Plates of Laser Beam Welding JF - Advanced Engineering Materials N2 - Duplex stainless steels combine the positive properties of its two phases, austenite and ferrite. Due to its good corrosion resistance, high tensile strength, and good ductility, it has multiple applications. But laser beam welding of duplex steels changes the balanced phase distribution in favor of ferrite. This results in a higher vulnerability to corrosion and a lower ductility. Herein, different powder combinations consisting of duplex and nickel for coating layers by laser metal deposition (LMD) are investigated. Afterward, laser tracks are welded, and the temperature cycles are measured. The ferrite content of the tracks is analyzed by feritscope, metallographic analysis, and electron backscatter diffraction. The goal is the development of a powder mixture allowing for a duplex microstructure in a two-step process, where first the edges of the weld partners are coated with the powder mixture by LMD and second those edges are laser beam welded. The powder mixture identified by the pretests is tested in the two-step process and analyzed by metallographic analysis, energy-dispersive X-ray spectroscopy, and Vickers hardness tests. The resulting weld seams show a balanced duplex microstructure with a homogenous nickel distribution and a hardness of the weld seam similar to the base material. KW - Duplex AISI 2205 KW - Laser metal deposition KW - Laser beam welding KW - Nickel KW - Stainless steels PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-547024 DO - https://doi.org/10.1002/adem.202101327 SN - 1438-1656 SP - 1 EP - 11 PB - Wiley-VCH CY - Weinheim AN - OPUS4-54702 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schneider, André A1 - Gumenyuk, Andrey A1 - Lammers, Marco A1 - Malletschek, A. A1 - Rethmeier, Michael T1 - Laser beam welding of thick titanium sheets in the field of marine technology JF - Physics procedia N2 - The ever larger requirements of the material selection in the range of maritime industry necessitate the application of high-tech materials. Titanium because of its excellent mechanical properties at low weight is an attractive alternative for the construction of ships. The goal of this investigation was to design a welding method for joining samples of 16 mm thick Ti3Al2.5 V. The welding experiments with a 20 kW Yb-fiber laser source and varying combinations of parameters were intended to qualify the laser beam welding process. The welding results were analyzed by non-destructive and destructive testing. In addition, the welding tests were recorded with two high-speed cameras to observe the weld pool and the vapor plume. The evaluation of the high-speed images in correlation with the results of non-destructive testing shows, that a significant improvement of process stability and weld quality can be achieved by the suppression of the vapor plume. KW - Titanium alloy KW - Maritime industry KW - Vapor plume KW - Laser beam welding KW - Ti3Al2.5V PY - 2014 DO - https://doi.org/10.1016/j.phpro.2014.08.046 SN - 1875-3892 VL - 56 SP - 582 EP - 590 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-31439 LA - eng 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 JF - Science and Technology of Welding and Joining 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 - Rethmeier, Michael A1 - Gook, Sergej A1 - Lammers, Marco A1 - Gumenyuk, Andrey T1 - Laser-Hybrid Welding of Thick Plates up to 32 mm Using a 20 kW Fibre Laser JF - Quarterly journal of the Japan Welding Society N2 - New brilliant high-power lasers such as disc laser and fibre laser open up new fields of applications for laser-hybrid welding, e.g. power generation, shipbuilding and pipeline construction. For the use of laser-hybrid welding in pipe laying, insensibility towards tolerances and the possibility of orbital welding are very important factors in addition to the weld seam quality. Within the scope of a basic research project, first promising results for laser-hybrid welding of thick materials could be demonstrated. As base material, the typical pipeline steel API 5L X65 was selected. With the help of a 20 kW fibre laser in combination with an arc-welding process it was possible to produce high-quality welds in plates of up to 20 mm thickness in a single pass and of up to 32 mm in three to five passes, both welded in position PA. Various joint preparations were examined to weld 20 mm thick plates in one pass. Besides different welding positions, gap bridgeability and misalignment were studied. Results for microhardness and Charpy toughness are presented to proof the applicability of laser-hybrid welding for joining in pipe laying. KW - Laser beam welding KW - High power fibre laser KW - Laser-hybrid welding KW - Tick plates KW - Pipe laying PY - 2009 DO - https://doi.org/10.2207/qjjws.27.74s SN - 0288-4771 VL - 27 IS - 2 SP - 74 EP - 79 CY - Tokyo, Japan AN - OPUS4-20345 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael A1 - Artinov, Antoni A1 - Meng, Xiangmeng A1 - Bakir, Nasim A1 - Üstündag, Ömer A1 - Bachmann, Marcel A1 - Gumenyuk, Andrey T1 - The bulging effect and its relevance in high power laser beam welding N2 - The present work deals with the recently confirmed widening of the weld pool interface, known as a bulging effect, and its relevance in high power laser beam welding. A combined experimental and numerical approach is utilized to study the influence of the bulge on the hot cracking formation and the transport of alloying elements in the molten pool. A technique using a quartz glass, a direct-diode laser illumination, a high-speed camera, and two thermal imaging cameras is applied to visualize the weld pool geometry in the longitudinal section. The study examines the relevance of the bulging effect on both, partial and complete penetration, as well as for different sheet thicknesses ranging from 8 mm to 25 mm. The numerical analysis shows that the formation of a bulge region is highly dependent on the penetration depth and occurs above 10 mm penetration depth. The location of the bulge correlates strongly with the cracking location. The obtained experimental and numerical results reveal that the bulging effect increases the hot cracking susceptibility and limits the transfer of alloying elements from the top of the weld pool to the weld root. T2 - 1st Annual Assembly and Conference of The Welding Federation of Africa (TWF-Africa) CY - Cairo, Egypt DA - 14.03.2023 KW - Laser beam welding KW - Melt pool dinamics PY - 2023 AN - OPUS4-58695 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Quiroz Penaranda, Vanessa A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Comparison between CO2- and Nd: YAG-laser beam welding of high-strength CrMnNi steels for the automotive industry JF - Welding in the world N2 - IIW-2326 Austenitic and austenitic-ferritic CrMnNi-stainless steels are suitable materials in the transport and automotive industry due to their high corrosion resistance and high strength that allows weight and cost savings. This study focuses on the laser weldability of a commercial lean duplex and an austenitic high manganese stainless steel. The impact of different laser sources, i.e. a 5 kW CO2- and a 4 kW Nd:YAG-laser, and of the main process parameters on the resulting weld quality will be investigated. One important aspect will concern the appearance of weld defects such as pores and hot cracks. The factors causing such internal imperfections will be analysed in order to find effective methods for preventing them. Weld microstructure and the associated corrosion and mechanical properties will be assessed with different techniques and adequate process parameters for high quality welds will be determined. The advantages and limitations of the applied welding processes will be evaluated for future applications. KW - Laser beam welding KW - Stainless steel KW - Austenitic KW - Duplex KW - Weld microstructure KW - Pores KW - Cracks KW - Corrosion KW - Tensile strength PY - 2012 SN - 0043-2288 SN - 1878-6669 VL - 56 IS - 11/12 SP - 129 EP - 142 PB - Springer CY - Oxford AN - OPUS4-27911 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -