TY - JOUR A1 - Graf, B. A1 - Marko, A. A1 - Petrat, T. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - 3D laser metal deposition: process steps for additive manufacturing JF - Welding in the World N2 - Laser metal deposition (LMD) is an established technology for two-dimensional surface coatings. It offers high deposition rates, high material flexibility, and the possibility to deposit material on existing components. Due to these features, LMD has been increasingly applied for additive manufacturing of 3D structures in recent years. Compared to previous coating applications, additive manufacturing of 3D structures leads to new challenges regarding LMD process knowledge. In this paper, the process steps for LMD as additive manufacturing technology are described. The experiments are conducted using titanium alloy Ti-6Al-4Vand Inconel 718. Only the LMD nozzle is used to create a shielding gas atmosphere. This ensures the high geometric flexibility needed for additive manufacturing, although issues with the restricted size and quality of the shielding gas atmosphere arise. In the first step, the influence of process parameters on the geometric dimensions of single weld beads is analyzed based on design of experiments. In the second step, a 3D build-up strategy for cylindrical specimen with high dimensional accuracy is described. Process parameters, travel paths, and cooling periods between layers are adjusted. Tensile tests show that mechanical properties in the as-deposited condition are close to wrought material. As practical example, the fir-tree root profile of a turbine blade is manufactured. The feasibility of LMD as additive technology is evaluated based on this component. KW - Laser metal deposition KW - Build-up strategy KW - Deposition rate KW - Additive manufacturing PY - 2018 DO - https://doi.org/10.1007/s40194-018-0590-x SN - 0043-2288 SN - 1878-6669 VL - 62 IS - 4 SP - 877 EP - 883 PB - Springer Berlin Heidelberg CY - Heidelberg AN - OPUS4-44868 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Siayah, A. A1 - El-Batahgy, A. A1 - Khafagi, S. A1 - Gumenyuk, Andrey A1 - Gook, S. A1 - Rethmeier, Michael T1 - A study on shielded metal arc welding of 9%Ni steel using non-conventional ferritic welding electrode for LNG facilities T2 - 4th International Conference on Welding and Failure Analysis of Engineering Materials N2 - The present research work aims at clarification of the effect of the welding electrode type on the mechanical properties of SMA welded joints of 9%Ni steel plates. Properties of produced SMA welded joints were evaluated using different non-destructive and destructive investigation methods. In comparison with the conventionally used Ni-based welding electrode ENiCrMo-3 (AWS A5.11), an experimentally produced non-conventional ferritic welding electrode with 11%Ni (ENi11-Company specification) has resulted in a better combination of the mechanical properties of SMA welded joints of this steel type for critical cryogenic applications. Besides, a positive economic impact for the experimentally produced non-conventional ferritic welding electrode, due to its lower cost, could be another attractive aspect. T2 - 4th International Conference on Welding and Failure Analysis of Engineering Materials CY - Aswan, Egypt DA - 19.11.2018 KW - 9%Ni steel, KW - SMAW KW - Conventional Ni-based austenitic welding electrode KW - Mechanical properties KW - Ferritic welding electrode PY - 2018 SP - W-21, 1 EP - 3 AN - OPUS4-46736 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bakir, Nasim A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - About the origin of solidification cracking in laser welded thick-walled structures T2 - 4th International Conference on Welding and Failure Analysis of Engineering Materials N2 - In this study, a three-dimensional CFD-simulation model was developed to simulate the fluid flow in the weld pool. The CFD-model showed a bulging region in the middle of the depth, which is separated from the top surface and bottom surface by two narrowing regions. It can be concluded that the interaction of the movement of the laser source with the Marangoni vortex leads to a teardrop shape at the upper and bottom surface of the workpiece. Additionally, it shows that the bulging in the weld is a result of the backflows on the upper and lower sides due to the thermo-capillary-driven flows. The weld pool shape was used as a heat source in a two-dimensional thermomechanical model, which allows a highly accurate transformation of the weld pool dimensions obtained from the CFD model. This developed technique allows the consideration of physical aspects, which cannot be considered when using traditional heat sources. The mechanical model has shown that the chronological order of the solidification of the weld has a significant influence on the nature and distribution of the stresses in the weld. High tensile stress has been observed in the bulging region, i.e. in the susceptible region for solidification cracking, when compared to the other narrowing regions, which show compressive stress. T2 - 4th International Conference on Welding and Failure Analysis of Engineering Materials CY - Aswan, Egypt DA - 19.11.2018 KW - Laser beam welding KW - Solidification cracking KW - Numerical simulation KW - Weld pool geometry KW - CFD-model KW - FE-model PY - 2018 SP - W-6, 1 EP - 10 CY - Aswan, Egypt AN - OPUS4-46735 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gumenyuk, Andrey A1 - Üstündağ, Ö. A1 - Fritzsche, A. A1 - Avilov, Vjaceslav A1 - Rethmeier, Michael T1 - Anwendung der Magnettechnik zum Laserstrahlschweißen von dickwandigen Konstruktionen N2 - Elektromagnetische Schmelzbadkontrolle wurde erfolgreich für Laser-MSG-Hybridprozess an einem (ferromagnetischen) 20 mm Baustahl und einem Pipelinestahl eingesetzt. Einlagiges Laserstrahlschweißen von dickwandigen(>20 mm) in PA-Position bei geringeren Schweißgeschwindigkeiten prinzipiell möglich. Reduzierung der Schweißgeschwindigkeit beim Laserstrahlschweißen hat eine Verringerung der notwendigen Laserleistung und eine Verbesserung der mechanisch-technologischen Eigenschaften von Schweißverbindungen zur Folge. T2 - Anwendertreffen Laserverbund Berlin-Brandenburg e.V. CY - Berlin, Germany DA - 17.10.2018 KW - Magnettechnik PY - 2018 AN - OPUS4-43943 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Petrat, T. A1 - Graf, B. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Build-up Strategies for Laser Metal Deposition in Additive Manufacturing T2 - Fraunhofer Direct Digital Manufacturing Conference - Konferenzband N2 - Laser Metal Deposition (LMD) as a technology for additive manufacturing allows the production of large components outside of closed working chambers. Industrial applications require a stable process as well as a constant deposition of the filler material in order to ensure uniform volume growth and reproducible mechanical properties. This paper deals with the influence of travel path strategies on temperature profile and material deposition. Meandering and spiral hatching strategies are used in the center as well as in the edge of a specimen. The temperature is measured with thermocouples attatched to the backside of the specimen. The tests are carried out on the materials S235JR and 316L. The results show a strong dependence of the maximum temperatures on the travel path strategy and the welding position on the component. T2 - Fraunhofer Direct Digital Manufacturing Conference (DDMC) CY - Berlin, Germany DA - 14.03.2018 KW - Additive Manufacturing KW - Temperature behavior KW - Laser Metal Deposition KW - Stainless Steel KW - 316L KW - Edge effects PY - 2018 SN - 978-3-8396-1320-7 VL - 1 SP - 1 EP - 6 PB - Fraunhofer-Gesellschaft CY - München AN - OPUS4-44719 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Petrat, T. A1 - Winterkorn, René A1 - Graf, B. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Build-up strategies for temperature control using laser metal deposition for additive manufacturing JF - Welding in the World N2 - The track geometry created with laser metal deposition (LMD) is influenced by various parameters. In this case, the laser power has an influence on the width of the track because of an increasing energy input. A larger melt pool is caused by a rising temperature. In the case of a longer welding process, there is also a rise in temperature, resulting in a change of the track geometry. This paper deals with the temperature profiles of different zigzag strategies and spiral strategies for additive manufacturing. A two-color pyrometer is used for temperature measurement on the component surface near the melt pool. Thermocouples measure the temperatures in deeper regions of a component. The welds are located in the center and in the edge area on a test part to investigate the temperature evolution under different boundary conditions. The experiments are carried out on substrates made from mild steel 1.0038 and with the filler material 316L. The investigations show an influence on the temperature evolution by the travel path strategy as well as the position on the part. This shows the necessity for the development and selection of build-up strategies for different part geometries in additive manufacturing by LMD. KW - Laser welding KW - Clad steels KW - Temperature distribution KW - Heat flow KW - Laser surfacing PY - 2018 DO - https://doi.org/10.1007/s40194-018-0604-8 SN - 0043-2288 SN - 1878-6669 VL - 62 IS - 5 SP - 1073 EP - 1081 PB - Springer AN - OPUS4-45773 LA - eng 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 JF - Journal of Materials Processing Tech. 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 - CONF A1 - Altenburg, Simon A1 - Maierhofer, Christiane A1 - Straße, Anne A1 - Gumenyuk, Andrey T1 - Comparison of MWIR thermography and high-speed NIR thermography in a laser metal deposition (LMD) process T2 - Proceedings of Conference QIRT 2018 N2 - Additive manufacturing (AM) offers a range of novel applications. However, the manufacturing process is complex and the production of defect-free parts with high reliability and durability is still a challenge. Thermography is a valuable tool for process surveillance, especially in metal AM processes. The high process temperatures allow one to use cameras usually operating in the visible spectral range. Here, we compare the results of measurements during the manufacturing process of a commercial laser metal deposition setup using a mid-wavelength-IR camera with those from a visual spectrum high-speed camera with band pass filter in the near-IR range. T2 - Conference QIRT 2018 CY - Berlin, Germany DA - 25.06.2018 KW - Additive manufacturing KW - Laser metal deposition KW - ProMoAM KW - Thermography PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-454993 UR - http://www.qirt.org/archives/qirt2018/papers/p35.pdf DO - https://doi.org/10.21611/qirt.2018.p35 SP - 1 EP - 5 PB - QIRT Council CY - Quebec, Canada AN - OPUS4-45499 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pavlov, V.A. A1 - Zavialov, S.V. A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Development of a measuring technology of strain field in welds T2 - 20th International Conference Digital Signal Processing N2 - In the article considered the problem of hot cracks occurrence during laser welding process. The main reason of their appearance is strain. The optical method for measuring full field strain locally near the solidification front during laser welding process is proposed. The proposed method of optical measurement allows to determine the real values of the critical strain for various materials characterizing the occurrence of hot cracks in laser welding process. T2 - 20th international conference "Digital signal processing and applications DSPA-2018" CY - Moskau, Russia DA - 28.03.2018 KW - Solidification cracking KW - Critical strain KW - Strain rate KW - Optical measurement KW - Laser welding KW - In situ strain PY - 2018 SN - 978-5-905278-33-4 SP - 749 EP - 754 AN - OPUS4-44910 LA - rus AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - El-Batahgy, A. A1 - Gook, S. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Effect of laser-beam and hybrid-laser-arc welding parameters and filler metal on microstructure and mechanical properties of thick heat-treated steel X8ni9+Qt640 for cryogenic service T2 - 4th International Conference on Welding and Failure Analysis of Engineering Materials N2 - The present research work encloses results of experimental investigations of the interaction between welding process parameters for laser-beam and hybrid-laser-arc as well as type of the filler metal and the achievable mechanical properties of the weld joints on steel grade X8Ni9+QT640 for cryogenic service containing 9% nickel. The results obtained contribute to the development and conversion in the industrial practice a new laser beam-based welding technology for the automated manufacturing of facilities for the liquefaction, storage and the transport of natural gases (LNG facilities). The results show, that the martensitic microstructure of the laser weld metal including low amount of retained austenite not exceeding 3.5% leads to the relatively low V-notch impact energy. The remarkable heterogeneity in the chemical composition of the weld metal through the weld thickness could be recognized in the case of hybrid-laser-arc welding with ERNiCrMo-3 austenitic filler metal, what also led to insufficient impact toughness of the weld metall. The most promising results could be achieved by using 11%Ni filler wire, which is similar to the base metal and provides a homogeneous microstructure with uniform distribution of Ni through the weld seam. It is remarkable, that a correlation between Charpy impact toughness and wire feeding speed and respectively process heat input exists. The highest toughness values were 134±58 J at -196C. The both laser as well as laser-hybrid welds passed the tensile test. The failure stress of 720±3 MPa with a fracture location in the base material was achieved for all samples tested. T2 - 4th International Conference on Welding and Failure Analysis of Engineering Materials CY - Aswan, Egypt DA - 19.11.2018 KW - Hybrid-laser-arc welding KW - Laser-beam welding, KW - Cryogenic steel KW - Microstructure KW - Tensile strength PY - 2018 SP - W-29, 1 EP - 10 AN - OPUS4-46738 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -