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Klaus Dilger
Institute of Joining and Welding, Technische Universität Braunschweig, Braunschweig, Germany

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Research paper
Published: 09 August 2021 in Welding in the World
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The so-called hairpin winding technology, which is specially tailored to electrical traction components, deploys rectangular plug-in copper wires in the stator. The fusion welding of the adjacent wire ends is associated with challenges due to the high thermal conductivity as well as the porosity formation of the copper. During this study, the electron beam (EB) welding of electrolytic tough pitch (ETP) and oxygen-free electronic grade (OFE) copper connectors was investigated. Subsequently, the specimens underwent X-ray computed tomography (CT) and metallographic examinations to characterize the joints. It was discovered that the residual oxygen content of the base material is responsible for the pore formation. With only a very low level of oxygen content in the copper, a porosity- and spatter-free welding can be reproducibly realized using the robust EB welding technology, especially for copper materials. By optimizing the parameters accordingly, joints exhibiting a low level of porosity were achieved even in the case of the alloy containing a high amount of residual oxygen. Beyond this, detailed analyses in terms of pore distribution were carried out and a good correlation between technological parameters and welding results was determined.

ACS Style

Tamás Tóth; Jonas Hensel; Sven Thiemer; Philipp Sieber; Klaus Dilger. Electron beam welding of rectangular copper wires applied in electrical drives. Welding in the World 2021, 1 -15.

AMA Style

Tamás Tóth, Jonas Hensel, Sven Thiemer, Philipp Sieber, Klaus Dilger. Electron beam welding of rectangular copper wires applied in electrical drives. Welding in the World. 2021; ():1-15.

Chicago/Turabian Style

Tamás Tóth; Jonas Hensel; Sven Thiemer; Philipp Sieber; Klaus Dilger. 2021. "Electron beam welding of rectangular copper wires applied in electrical drives." Welding in the World , no. : 1-15.

Journal article
Published: 04 August 2021 in Metals
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Increasing the service life of die casting dies is an important goal of the foundry industry. Approaches are either material- or process-related. Despite new material concepts, hot work steels such as H11 are still predominantly used in the uncoated condition for die casting dies. In order to withstand the stresses that occur, this steel is used exclusively in the quenched and tempered condition. Required properties such as high high-temperature strength and high hardness combined with high toughness are, in principle, contradictory and can only be adjusted consistently over the entire die by furnace-based heat treatment. However, the results of various investigations have shown that improvements in the thermal shock resistance and wear resistance of hot work tool steels can be achieved by thermally influencing the microstructure near the surface. Based on these studies and related findings, an approach to surface heat treatment using the electron beam was developed. Due to the particle character of the radiation and the associated possibility of high-frequency beam deflection, the electron beam offers significantly greater flexibility in energy input into the workpiece surface compared with lasers or induction. The overall technological concept envisages replacing furnace-based heat treatment in the production of casting dies by localized and demand-oriented boundary layer heat treatment with the electron beam. The experiments include, on the one hand, the experimental determination of a suitable temperature–time interval with a focus on short-term austenitization. On the other hand, a simulation-based approach of boundary layer heat treatment with validation of a suitable heat source is investigated. Regarding short-term austenitization, the corresponding temperature and time range could be narrowed down more precisely. Some of these parameter combinations seem to be very suitable for practical use. The test specimens show a hard surface layer with a depth of at least up to 6 mm and a very tough buffer layer. Numerical simulation is used to estimate the resulting metallurgical microstructure and the achievable hardness as a function of the temperature–time interval. In addition, the results provided show the possibility of determining and optimizing the material properties by means of a simulation-based approach within the framework of a purely digital process planning and subsequently transferring them into a process planning. In the technical implementation, a temperature control was first established by means of a two-color pyrometer. In the further course of research, the pyrometer will be supplemented by an internally installed infrared camera, which will allow the reproducible setting of specified temperature profiles even for complex, large-area contours in the future.

ACS Style

Torsten Schuchardt; Sebastian Müller; Klaus Dilger. A Near-Surface Layer Heat Treatment of Die Casting Dies by Means of Electron-Beam Technology. Metals 2021, 11, 1236 .

AMA Style

Torsten Schuchardt, Sebastian Müller, Klaus Dilger. A Near-Surface Layer Heat Treatment of Die Casting Dies by Means of Electron-Beam Technology. Metals. 2021; 11 (8):1236.

Chicago/Turabian Style

Torsten Schuchardt; Sebastian Müller; Klaus Dilger. 2021. "A Near-Surface Layer Heat Treatment of Die Casting Dies by Means of Electron-Beam Technology." Metals 11, no. 8: 1236.

Journal article
Published: 20 May 2021 in Applied Sciences
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Wire arc additive manufacturing (WAAM) is a direct energy deposition (DED) process with high deposition rates, but deformation and distortion can occur due to the high energy input and resulting strains. Despite great efforts, the prediction of distortion and resulting geometry in additive manufacturing processes using WAAM remains challenging. In this work, an artificial neural network (ANN) is established to predict welding distortion and geometric accuracy for multilayer WAAM structures. For demonstration purposes, the ANN creation process is presented on a smaller scale for multilayer beads on plate welds on a thin substrate sheet. Multiple concepts for the creation of ANNs and the handling of outliers are developed, implemented, and compared. Good results have been achieved by applying an enhanced ANN using deformation and geometry from the previously deposited layer. With further adaptions to this method, a prediction of additive welded structures, geometries, and shapes in defined segments is conceivable, which would enable a multitude of applications for ANNs in the WAAM-Process, especially for applications closer to industrial use cases. It would be feasible to use them as preparatory measures for multi-segmented structures as well as an application during the welding process to continuously adapt parameters for a higher resulting component quality.

ACS Style

Christian Wacker; Markus Köhler; Martin David; Franziska Aschersleben; Felix Gabriel; Jonas Hensel; Klaus Dilger; Klaus Dröder. Geometry and Distortion Prediction of Multiple Layers for Wire Arc Additive Manufacturing with Artificial Neural Networks. Applied Sciences 2021, 11, 4694 .

AMA Style

Christian Wacker, Markus Köhler, Martin David, Franziska Aschersleben, Felix Gabriel, Jonas Hensel, Klaus Dilger, Klaus Dröder. Geometry and Distortion Prediction of Multiple Layers for Wire Arc Additive Manufacturing with Artificial Neural Networks. Applied Sciences. 2021; 11 (10):4694.

Chicago/Turabian Style

Christian Wacker; Markus Köhler; Martin David; Franziska Aschersleben; Felix Gabriel; Jonas Hensel; Klaus Dilger; Klaus Dröder. 2021. "Geometry and Distortion Prediction of Multiple Layers for Wire Arc Additive Manufacturing with Artificial Neural Networks." Applied Sciences 11, no. 10: 4694.

Research paper
Published: 18 May 2021 in Welding in the World
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In the meantime, it’s well known that post-weld fatigue strength improvement techniques for welded structures like high-frequency mechanical impact (HFMI) treatment increase the fatigue live of welded joints. Although the current design recommendations for HFMI-treated welded joints give first design proposals for the HFMI-treated welds, in practice the application of HFMI treatment and the associated increase in fatigue resistance are still being discussed. There are, for example, reservations regarding the efficiency of HFMI-treated welded joints under variable amplitude loading (VAL). This paper analyses first results for the sequence effect of VAL of a p (1/3) spectrum on the service fatigue strength of HFMI-treated transverse stiffeners (TS) of mild steel (S355). Fatigue test results with random and high-low loading for the two states as-welded (AW) and HFMI-treated joints will be presented. The modified linear damage accumulation and the failure locations will be discussed. The experimental results show a clear change in the slope of the S-N curve from the as-welded (AW) state to the HFMI state and additionally in the HFMI state from constant amplitude loading (CAL) to variable amplitude loading (VAL). It was particularly noticeable in the experimental results of all tested HFMI series that the specimens failed exclusively in the base material 2–4mm before the HFMI-treated welds. The presented results of the investigations show that with application of the nominal stress concept, no sequence effect was recognizable.

ACS Style

R. Schiller; D. Löschner; P. Diekhoff; I. Engelhardt; Th. Nitschke-Pagel; K. Dilger. Sequence effect of p(1/3) spectrum loading on service fatigue strength of as-welded and high-frequency mechanical impact (HFMI)-treated transverse stiffeners of mild steel. Welding in the World 2021, 1 -19.

AMA Style

R. Schiller, D. Löschner, P. Diekhoff, I. Engelhardt, Th. Nitschke-Pagel, K. Dilger. Sequence effect of p(1/3) spectrum loading on service fatigue strength of as-welded and high-frequency mechanical impact (HFMI)-treated transverse stiffeners of mild steel. Welding in the World. 2021; ():1-19.

Chicago/Turabian Style

R. Schiller; D. Löschner; P. Diekhoff; I. Engelhardt; Th. Nitschke-Pagel; K. Dilger. 2021. "Sequence effect of p(1/3) spectrum loading on service fatigue strength of as-welded and high-frequency mechanical impact (HFMI)-treated transverse stiffeners of mild steel." Welding in the World , no. : 1-19.

Journal article
Published: 23 February 2021 in International Journal of Pressure Vessels and Piping
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Duplex stainless steels are commonly used in the chemical as well as in the oil and gas industry due to their excellent mechanical properties and corrosion resistance. In this research, electron beam welded duplex stainless steel joints were investigated regarding their microstructure, mechanical and corrosion properties. Since the balance between austenite and ferrite is determined by the cooling rate and the chemical composition, a pre-placed nickel-based filler material was added to the weld joint in order to promote the austenite formation, which is suppressed by the rapid cooling. This is a common phenomenon in power beam welding processes. A suitable weld geometry was achieved by oscillating and defocusing the electron beam. Thereby, the process tolerates the diverse disturbances resulting from the production as well as an unexpected occurrence of a non-zero gap size. Using a nickel-based filler wire, the welds show an excellent austenite-ferrite balance, but with heterogeneous distribution over depth due to the insufficient dilution of filler wire and base material. As a result of a balanced microstructure, the post-welding heat treatment may become necessary solely in exceptional cases. The measured values of tensile strength as well as the impact energy meet all the requirements of the EN 10088-2 and EN ISO 17781, respectively. Furthermore, the critical pitting temperature values measured in the various regions of the seam are lower compared to the base material, although, they are above of the acceptance value according to EN ISO 17781.

ACS Style

Tamás Tóth; Sergii Krasnorutskyi; Jonas Hensel; Klaus Dilger. Electron beam welding of 2205 duplex stainless steel using pre-placed nickel-based filler material. International Journal of Pressure Vessels and Piping 2021, 191, 104354 .

AMA Style

Tamás Tóth, Sergii Krasnorutskyi, Jonas Hensel, Klaus Dilger. Electron beam welding of 2205 duplex stainless steel using pre-placed nickel-based filler material. International Journal of Pressure Vessels and Piping. 2021; 191 ():104354.

Chicago/Turabian Style

Tamás Tóth; Sergii Krasnorutskyi; Jonas Hensel; Klaus Dilger. 2021. "Electron beam welding of 2205 duplex stainless steel using pre-placed nickel-based filler material." International Journal of Pressure Vessels and Piping 191, no. : 104354.

Chapter
Published: 27 November 2020 in Dubbel Taschenbuch für den Maschinenbau 2: Anwendungen
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Kapitel basiert auf: H. Wohlfahrt†, K. Thomas† und M. Kaßner†. Beim Verbindungsschweißen werden die Teile durch Schweißnähte am Schweißstoß zum Schweißteil zusammengefügt. Mehrere Schweißteile ergeben die Schweißgruppe und mehrere Schweißgruppen die Schweißkonstruktion. Durch Auftragschweißen können verschlissene Flächen von Werkstücken neu aufgetragen, Oberflächen weniger verschleißfester Werkstoffe mit Schichten aus Verschleißwerkstoffen gepanzert (Schweißpanzern), korrosiv unbeständige Trägerwerkstoffe mit korrosionsbeständigen Werkstoffen „plattiert“ (Schweißplattieren) oder zwischen nichtartgleichen Werkstoffen kann durch den Auftragwerkstoff eine beanspruchungsgerechte Bindung erzielt werden (Puffern). Neben Metallen lassen sich auch viele Kunststoffe durch Schweißen miteinander verbinden.

ACS Style

Helmut Wohlfahrt; Thomas Widder; Manfred Kaßner; Karl Thomas; Klaus Dilger; Heinz Mertens; Robert Liebich. Bauteilverbindungen. Dubbel Taschenbuch für den Maschinenbau 2: Anwendungen 2020, 155 -243.

AMA Style

Helmut Wohlfahrt, Thomas Widder, Manfred Kaßner, Karl Thomas, Klaus Dilger, Heinz Mertens, Robert Liebich. Bauteilverbindungen. Dubbel Taschenbuch für den Maschinenbau 2: Anwendungen. 2020; ():155-243.

Chicago/Turabian Style

Helmut Wohlfahrt; Thomas Widder; Manfred Kaßner; Karl Thomas; Klaus Dilger; Heinz Mertens; Robert Liebich. 2020. "Bauteilverbindungen." Dubbel Taschenbuch für den Maschinenbau 2: Anwendungen , no. : 155-243.

Journal article
Published: 08 September 2020 in Metals
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In the case of casting processes with permanent molds, there is still a relatively pronounced lack of knowledge regarding the locally prevailing heat transfer between casts and mold. This in turn results in an insufficient knowledge of the microstructure and the associated material properties in the areas of the casting component close to the surface. Therefore, this work deals with the design and evaluation of a test tool with an integrated sensor system for temperature measurements, which was applied to obtain a time-dependent heat transfer coefficient (HTC) during casting solidification. For this purpose, the setup, design and computational approach are described first. Special attention is paid to the qualification of the multi-depth sensor and the calculation method. For the calculations, an inverse estimation method (nonlinear sequential function) was used to obtain the HTC profiles from the collected data. The developed sensor technology was used in a test mold to verify the usability of the sensor technology and the plausibility of the obtained calculation results under real casting conditions and associated temperature loads. Both the experimental temperature profiles and the HTC profiles showed that, in the evaluated casting series, the peak values determined were close to each other and reached values between 6000 W/(m2·K) and 8000 W/(m2·K) during solidification.

ACS Style

Yosra Kouki; Sebastian Müller; Torsten Schuchardt; Klaus Dilger. Development of an Instrumented Test Tool for the Determination of Heat Transfer Coefficients for Die Casting Applications. Metals 2020, 10, 1206 .

AMA Style

Yosra Kouki, Sebastian Müller, Torsten Schuchardt, Klaus Dilger. Development of an Instrumented Test Tool for the Determination of Heat Transfer Coefficients for Die Casting Applications. Metals. 2020; 10 (9):1206.

Chicago/Turabian Style

Yosra Kouki; Sebastian Müller; Torsten Schuchardt; Klaus Dilger. 2020. "Development of an Instrumented Test Tool for the Determination of Heat Transfer Coefficients for Die Casting Applications." Metals 10, no. 9: 1206.

Journal article
Published: 15 July 2020 in Metals
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Wire and arc additive manufacturing (WAAM) provides a promising alternative to conventional machining for the production of large structures with complex geometry, as well as individualized low quantity components, using cost-efficient production resources. Due to the layer-by-layer build-up approach, process conditions, such as energy input, deposition patterns and heat conduction during the additive manufacturing process result in a unique thermal history of the structure, affecting the build-up properties. This experimental study aims to describe the effects of thermal cycling on the geometrical and material properties of wire arc additive manufactured Al-5356 aluminum alloy. Under consideration, that Al-5356 is a non-heat treatable alloy, a significant effect on geometrical formation is expected. Linear wall samples were manufactured using pulsed cold metal transfer (CMT-P) under variation of wire-feed rate, travel speed and interpass temperatures. The samples were analyzed in terms of geometry; microstructural composition; hardness and residual stress. Furthermore, the mechanical properties were determined in different building directions.

ACS Style

Markus Köhler; Jonas Hensel; Klaus Dilger. Effects of Thermal Cycling on Wire and Arc Additive Manufacturing of Al-5356 Components. Metals 2020, 10, 952 .

AMA Style

Markus Köhler, Jonas Hensel, Klaus Dilger. Effects of Thermal Cycling on Wire and Arc Additive Manufacturing of Al-5356 Components. Metals. 2020; 10 (7):952.

Chicago/Turabian Style

Markus Köhler; Jonas Hensel; Klaus Dilger. 2020. "Effects of Thermal Cycling on Wire and Arc Additive Manufacturing of Al-5356 Components." Metals 10, no. 7: 952.

Research paper
Published: 25 June 2020 in Welding in the World
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The notch stress concept has been established for fatigue life calculations of welded components. One of its advantages is that the S-N curve is not based on an S-N curve catalog in which the user has to identify a suitable FAT class; instead, a single S-N curve (based on modeling, failure location, and material) is used for different weld geometries. In return, however, the weld needs to be modeled in a detailed manner for finite element analysis. The evaluation of experimental fatigue results collected in a database shows a relatively high degree of scattering (low accuracy) of the strengths calculated according to the notch stress concept. With fatigue tests on different specimen geometries manufactured from the same welded base plates, a correlation between the highly stressed weld seam length and the experimentally determined notch stress strength can be observed. The fatigue strength decreases with the increasing length of the highly stressed weld seam area. The latter quantity can be calculated using the finite element simulations that are needed to determine the notch stress. The presented results are used to describe the statistical size effect as a qualitative influence and quantitative support factor that can be used within the notch stress concept to increase its accuracy.

ACS Style

Andreas Deinböck; Ann-Christin Hesse; Michael Wächter; Jonas Hensel; Alfons Esderts; Klaus Dilger. Increased accuracy of calculated fatigue resistance of welds through consideration of the statistical size effect within the notch stress concept. Welding in the World 2020, 64, 1725 -1736.

AMA Style

Andreas Deinböck, Ann-Christin Hesse, Michael Wächter, Jonas Hensel, Alfons Esderts, Klaus Dilger. Increased accuracy of calculated fatigue resistance of welds through consideration of the statistical size effect within the notch stress concept. Welding in the World. 2020; 64 (10):1725-1736.

Chicago/Turabian Style

Andreas Deinböck; Ann-Christin Hesse; Michael Wächter; Jonas Hensel; Alfons Esderts; Klaus Dilger. 2020. "Increased accuracy of calculated fatigue resistance of welds through consideration of the statistical size effect within the notch stress concept." Welding in the World 64, no. 10: 1725-1736.

Journal article
Published: 29 April 2020 in Journal of Manufacturing and Materials Processing
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In recent decades, beam welding processes have been set up as a key technology for joining applications in automotive engineering and particularly in gearbox manufacturing. Due to their high beam quality, energy efficiency, reliability as well as flexible beam guidance, modern solid-state lasers offer numerous advantages, but also pose increased requirements on the production and positional accuracy of the components for the joining process. In particular, small-focus diameters present a challenge for components with process-induced tolerances, i.e., disc carriers in automatic transitions. Furthermore, welding processes utilizing solid-state lasers show an increased spatter formation during welding at high welding speeds. Accordingly, the primary objective of the presented work consists in extending the current areas of application for solid-state laser beam welding in gearbox manufacturing through an improved process reliability regarding tolerance compensation and spatter formation. Therefore, this experimental study aimed to describe the effects of a dynamic beam oscillation in combination with a reduced ambient pressure in the process environment on both gap bridging ability and spatter formation during the laser beam welding of case hardening steel. For basic process evaluations, laser beam welding at reduced ambient pressure and laser beam welding with dynamic beam oscillation were initially studied separately. Following a basic process evaluation, samples for 2 mm full-penetration-welds with varying gap sizes were analyzed in terms of weld seam geometry and weld spatter formation.

ACS Style

Markus Köhler; Tamás Tóth; Andreas Kreybohm; Jonas Hensel; Klaus Dilger. Effects of Reduced Ambient Pressure and Beam Oscillation on Gap Bridging Ability during Solid-State Laser Beam Welding. Journal of Manufacturing and Materials Processing 2020, 4, 40 .

AMA Style

Markus Köhler, Tamás Tóth, Andreas Kreybohm, Jonas Hensel, Klaus Dilger. Effects of Reduced Ambient Pressure and Beam Oscillation on Gap Bridging Ability during Solid-State Laser Beam Welding. Journal of Manufacturing and Materials Processing. 2020; 4 (2):40.

Chicago/Turabian Style

Markus Köhler; Tamás Tóth; Andreas Kreybohm; Jonas Hensel; Klaus Dilger. 2020. "Effects of Reduced Ambient Pressure and Beam Oscillation on Gap Bridging Ability during Solid-State Laser Beam Welding." Journal of Manufacturing and Materials Processing 4, no. 2: 40.

Journal article
Published: 10 April 2020 in Manufacturing Review
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Monitoring the deformation within an adhesive joint during the curing cycle provides valuable information regarding the build-up of thermal strain and stress. Distributed fibre optic sensors are very useful for spatial continuous measurements of deformation or temperature. Integrated into a hybrid joint, the thermal curing process of the adhesive can be monitored. This detailed insight into the joint helps to understand the deformation and thereby also the resulting stress. Analysing the deformation process establishes the foundation to adapt techniques to reduce the thermally induced deformation and thereby the resulting stress.

ACS Style

Hinrich Grefe; Dennis Weiser; Maja Wanda Kandula; Klaus Dilger. Deformation measurement within adhesive bonds of aluminium and CFRP using advanced fibre optic sensors. Manufacturing Review 2020, 7, 14 .

AMA Style

Hinrich Grefe, Dennis Weiser, Maja Wanda Kandula, Klaus Dilger. Deformation measurement within adhesive bonds of aluminium and CFRP using advanced fibre optic sensors. Manufacturing Review. 2020; 7 ():14.

Chicago/Turabian Style

Hinrich Grefe; Dennis Weiser; Maja Wanda Kandula; Klaus Dilger. 2020. "Deformation measurement within adhesive bonds of aluminium and CFRP using advanced fibre optic sensors." Manufacturing Review 7, no. : 14.

Journal article
Published: 20 March 2020 in Materials
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The welding of aluminium high pressure die castings is a well known and broadly investigated challenge in various fields of industry and research. Prior research in this specific field mainly focused on the optimisation of the welding and the casting process and on the cause of the frequently occurring porosity and incomplete fusion phenomena, whereas the impacts of these defects have hardly been addressed. Therefore, the underlying study presents the investigation of weldments in EN AC-AlSi10MnMg high pressure aluminium die castings by linear elastic finite element analysis based on X-ray computed tomography as a novel approach. Hereby, four laser weldments with differing surfaces and pore contents were investigated by X-ray computed tomography and tensile testing. Based on the voxel datasets of the porous weldments, triangular finite element meshes were generated and a numerical finite element analysis was conducted. Good agreement of the stress–strain curves between the simulations and the experiments was achieved.

ACS Style

Fabian Teichmann; Arne Ziemer; Martin Leitner; Jonas Hensel; Klaus Dilger. Linear Elastic FE-Analysis of Porous, Laser Welded, Heat Treatable, Aluminium High Pressure Die Castings Based on X-Ray Computed Tomography Data. Materials 2020, 13, 1420 .

AMA Style

Fabian Teichmann, Arne Ziemer, Martin Leitner, Jonas Hensel, Klaus Dilger. Linear Elastic FE-Analysis of Porous, Laser Welded, Heat Treatable, Aluminium High Pressure Die Castings Based on X-Ray Computed Tomography Data. Materials. 2020; 13 (6):1420.

Chicago/Turabian Style

Fabian Teichmann; Arne Ziemer; Martin Leitner; Jonas Hensel; Klaus Dilger. 2020. "Linear Elastic FE-Analysis of Porous, Laser Welded, Heat Treatable, Aluminium High Pressure Die Castings Based on X-Ray Computed Tomography Data." Materials 13, no. 6: 1420.

Journal article
Published: 03 December 2019 in Batteries
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Laser cutting is a promising technology for the singulation of conventional and advanced electrodes for lithium-ion batteries. Even though the continuous development of laser sources, beam guiding, and handling systems enable industrial relevant high cycle times, there are still uncertainties regarding the influence of, for this process, typical cutting edge characteristics on the electrochemical performance. To investigate this issue, conventional anodes and cathodes were cut by a pulsed fiber laser with a central emission wavelength of 1059–1065 nm and a pulse duration of 240 ns. Based on investigations considering the pulse repetition frequency, cutting speed, and line energy, a cell setup of anodes and cathodes with different cutting edge characteristics were selected. The experiments on 9 Ah pouch cells demonstrated that the cutting edge of the cathode had a greater impact on the electrochemical performance than the cutting edge of the anode. Furthermore, the results pointed out that on the cathode side, the contamination through metal spatters, generated by the laser current collector interaction, had the largest impact on the electrochemical performance.

ACS Style

Tobias Jansen; Maja W. Kandula; Sven Hartwig; Louisa Hoffmann; Wolfgang Haselrieder; Klaus Dilger. Influence of Laser-Generated Cutting Edges on the Electrical Performance of Large Lithium-Ion Pouch Cells. Batteries 2019, 5, 73 .

AMA Style

Tobias Jansen, Maja W. Kandula, Sven Hartwig, Louisa Hoffmann, Wolfgang Haselrieder, Klaus Dilger. Influence of Laser-Generated Cutting Edges on the Electrical Performance of Large Lithium-Ion Pouch Cells. Batteries. 2019; 5 (4):73.

Chicago/Turabian Style

Tobias Jansen; Maja W. Kandula; Sven Hartwig; Louisa Hoffmann; Wolfgang Haselrieder; Klaus Dilger. 2019. "Influence of Laser-Generated Cutting Edges on the Electrical Performance of Large Lithium-Ion Pouch Cells." Batteries 5, no. 4: 73.

Journal article
Published: 04 November 2019 in International Journal of Adhesion and Adhesives
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A significant influence on the strength of adhesively bonded fibre-reinforces plastics is the local ply orientation of the adherend, especially in a hybrid or multi-material joint. In this paper, the joint strength and failure behaviour is investigated for different ply orientations using single lap shear tests. The tests are performed with quasi static loading and also under high strain rates. Digital image correlation is used to monitor the specimen deformation and separation. Analysing the cracking process, a distinction between the appearance of a cohesive failure pattern and an actual cohesively progressing failure can be made. This provides an insight to the fracture mechanics and allows a comparison between high and low strain rates. A correlation between the cracking behaviour and the maximum load and displacement is observed.

ACS Style

H. Grefe; M.W. Kandula; Klaus Dilger. Influence of the fibre orientation on the lap shear strength and fracture behaviour of adhesively bonded composite metal joints at high strain rates. International Journal of Adhesion and Adhesives 2019, 97, 102486 .

AMA Style

H. Grefe, M.W. Kandula, Klaus Dilger. Influence of the fibre orientation on the lap shear strength and fracture behaviour of adhesively bonded composite metal joints at high strain rates. International Journal of Adhesion and Adhesives. 2019; 97 ():102486.

Chicago/Turabian Style

H. Grefe; M.W. Kandula; Klaus Dilger. 2019. "Influence of the fibre orientation on the lap shear strength and fracture behaviour of adhesively bonded composite metal joints at high strain rates." International Journal of Adhesion and Adhesives 97, no. : 102486.

Reviews
Published: 26 September 2019 in The Journal of Adhesion
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The aim of this investigation is to generate a basic understanding of the formation of the joining zone of fusion bonded hybrid joints made of press hardened steel (22MnB5) and polyamide 6 (PA6) glass mat reinforced thermoplastic (GMT). To this end, lap-shear samples are produced by varying the steel surface and the fusion bonding temperature. In order to evaluate the resulting joint properties, micrographs of the joining zone are analyzed. Moreover, roughness measurements, scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) investigations are used to characterize the steel surface and undercut geometries before joining. By correlating the results of the interface characterization with the mechanical joint strength, optimized fusion bonding parameters can be defined. The results outline the necessity of heating the metal above the melting temperature of the GMT material in order to prevent a solidification in the joining zone. Additionally, the GMT material has to be melted completely to allow the GMT to flow into the geometry undercuts of the AlSi surface. The maximum lap-shear strength is 22.9 ± 2.1 MPa. It was achieved with the samples showing to a metal temperature of 280°C and a GMT temperature of 260°C.

ACS Style

L. Kaempf; Klaus Dilger; S. Hartwig. Bonding behavior of fusion bonded hybrid joints with press hardened steel and glass mat reinforced thermoplastic. The Journal of Adhesion 2019, 96, 113 -129.

AMA Style

L. Kaempf, Klaus Dilger, S. Hartwig. Bonding behavior of fusion bonded hybrid joints with press hardened steel and glass mat reinforced thermoplastic. The Journal of Adhesion. 2019; 96 (1-4):113-129.

Chicago/Turabian Style

L. Kaempf; Klaus Dilger; S. Hartwig. 2019. "Bonding behavior of fusion bonded hybrid joints with press hardened steel and glass mat reinforced thermoplastic." The Journal of Adhesion 96, no. 1-4: 113-129.

Journal article
Published: 23 September 2019 in Progress in Organic Coatings
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Water uptake and diffusion in polymer coatings, which can induce electrochemical reactions at the polymer-metal interface, are the main cause for the degradation and failure of polymer-coated metals under service conditions. Herein electrochemical impedance spectroscopy has been used to study the water uptake and interfacial reaction of an epoxy coated galvanized steel system during exposure to 3.5 wt.% NaCl solutions at 20, 37, 50 and 65 °C for up to 620 h, respectively. Water diffusion coefficient and its temperature dependence were determined from the capacitance change of the epoxy coating upon exposure at early stage. The electrochemical impedance spectra were analyzed using different equivalent circuit models to derive the time-dependence of the parameters of the coating (Cc, Rpo), delaminated area (fb, θ10Hz, α) and interfacial processes (Cdl, Rct, fb, θ10Hz). It is found that the breakpoint frequency, fb and the phase angle at 10 Hz, θ10Hz show a good agreement in monitoring the degradation dynamic of the epoxy-coated galvanized steel system. The delaminated area ratio at the epoxy-steel interface increased from about 4.7 × 10−6 to about 1.1 × 10-4 before and after aging at 50 °C for 620 h. Thus the combined analysis of the time evolution of the breakpoint frequency, fb and the phase angle θ10Hz provides a simple and consistent procedure to evaluate the performance of polymer coatings and to quantitatively monitor the delamination dynamic at the polymer-metal interface.

ACS Style

Changfeng Fan; Jianmin Shi; Klaus Dilger. Water uptake and interfacial delamination of an epoxy-coated galvanized steel: An electrochemical impedance spectroscopic study. Progress in Organic Coatings 2019, 137, 105333 .

AMA Style

Changfeng Fan, Jianmin Shi, Klaus Dilger. Water uptake and interfacial delamination of an epoxy-coated galvanized steel: An electrochemical impedance spectroscopic study. Progress in Organic Coatings. 2019; 137 ():105333.

Chicago/Turabian Style

Changfeng Fan; Jianmin Shi; Klaus Dilger. 2019. "Water uptake and interfacial delamination of an epoxy-coated galvanized steel: An electrochemical impedance spectroscopic study." Progress in Organic Coatings 137, no. : 105333.

Letters
Published: 11 September 2019 in The Journal of Adhesion
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The Fused-Layer-Modeling process is an established process for Additive Manufacturing of polymers and provides many possibilities for the individualization of parts. One of this customization is the individualization of injection molded parts by a direct extrusion method based on Fused-Layer-Modeling. One of the biggest challenges in establishing this bonding process is to workout testing strategies which can help to optimize the bonding area. In general, for Additive Manufacturing there are no existing standards of experimental tests. Most of the time, the standards of related manufacturing technologies like bonding and other joining processes are used and modified for each application. Nonetheless, the opportunity for testing Fused-Layer-Modeling parts is helpful to get useful and repeatable results to investigate interlayer and other mechanical properties. This paper investigates the strength of the bonding area between Fused-Layer-Modeling parts and injection molded parts. Therefore, we modify two different standards of conventional joining processes and present the results. In the first step, all modifications from the original standard including constructions and dimensions are shown and valued. In the next step, we evaluate the mechanical properties of both bonding partners and material combination. The strength of the bonding is compared against the maximum strength in the z-direction of the Fused-Layer-Modeling part since this is the strength limitation of the layer-by-layer process. In order to guaranty that the specific circumstances of this bonding process are covered and comparable results are realized, we developed new standards.

ACS Style

A. Richter; F. Fischer; Klaus Dilger. Evaluation of various standards of adhesion properties between fused-layer-modeling parts and injection molded parts. The Journal of Adhesion 2019, 96, 13 -32.

AMA Style

A. Richter, F. Fischer, Klaus Dilger. Evaluation of various standards of adhesion properties between fused-layer-modeling parts and injection molded parts. The Journal of Adhesion. 2019; 96 (1-4):13-32.

Chicago/Turabian Style

A. Richter; F. Fischer; Klaus Dilger. 2019. "Evaluation of various standards of adhesion properties between fused-layer-modeling parts and injection molded parts." The Journal of Adhesion 96, no. 1-4: 13-32.

Journal article
Published: 23 August 2019 in Materials
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From the viewpoint of mechanics, weld cracking tends to occur if the induced tensile stress surpasses a certain value for the particular materials and the welding processes. Welding residual stresses (WRS) can be profoundly affected by the restraint conditions of the welded structures. For estimating the tendency of weld cracking, the small-scale H-type slit joints have been widely used for cracking tests. However, it is still hard to decide whether the real large-scale component can also be welded without cracking even though the tested weld cracking specimens on the laboratory scale can be welded without cracking. In this study, the intensity of restraint which quantitatively indicates how much a joint is restrained is used. The influence of restraint condition (intensity of restraint) on WRS is systematically investigated using both the numerical simulation and the experimental method. The achievement obtained in the current work is very beneficial to design effective H-type self-restrained cracking test specimens for evaluating the sensitivity of the material and the welding procedures for weld cracking in the real large-scale components.

ACS Style

Jiamin Sun; Jonas Hensel; Thomas Nitschke-Pagel; Klaus Dilger. Influence of Restraint Conditions on Welding Residual Stresses in H-Type Cracking Test Specimens. Materials 2019, 12, 2700 .

AMA Style

Jiamin Sun, Jonas Hensel, Thomas Nitschke-Pagel, Klaus Dilger. Influence of Restraint Conditions on Welding Residual Stresses in H-Type Cracking Test Specimens. Materials. 2019; 12 (17):2700.

Chicago/Turabian Style

Jiamin Sun; Jonas Hensel; Thomas Nitschke-Pagel; Klaus Dilger. 2019. "Influence of Restraint Conditions on Welding Residual Stresses in H-Type Cracking Test Specimens." Materials 12, no. 17: 2700.

Research paper
Published: 02 August 2019 in Welding in the World
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The economic efficiency of die-casting processes is largely determined by the lifetime of the die. Such dies are exposed to high cyclical loads of thermal, mechanical, tribological and chemical loads during operation. These loads cause various types of damage, which reduce the lifetime. If the production comes to an unexpected stop due to a critical defect in the casting tool, repair welding is often the only way to return the tool to production immediately. At present, primarily manual TIG or plasma-welding processes are used for this purpose, which, however, exhibit insufficient process reliability and thus achieve an insufficient extension of lifetime. The primary objective of the research project is therefore the development of a technology for the economical regeneration of locally damaged die-casting dies with improved metallurgical properties compared with conventional repair welds. This forms an elementary basis for extending the service life of dies in series production. For this reason, electron-beam welding is to be qualified because of its possibilities for variable, need-adapted designs of the overall heat balance and the use of filler material as a welding process for industrially used hot-work steels.

ACS Style

T. Schuchardt; S. Müller; K. Dilger. Remanufacturing of die casting dies made of hot-work steels by using the wire-based electron-beam welding with an in situ heat treatment. Welding in the World 2019, 63, 1669 -1679.

AMA Style

T. Schuchardt, S. Müller, K. Dilger. Remanufacturing of die casting dies made of hot-work steels by using the wire-based electron-beam welding with an in situ heat treatment. Welding in the World. 2019; 63 (6):1669-1679.

Chicago/Turabian Style

T. Schuchardt; S. Müller; K. Dilger. 2019. "Remanufacturing of die casting dies made of hot-work steels by using the wire-based electron-beam welding with an in situ heat treatment." Welding in the World 63, no. 6: 1669-1679.

Research paper
Published: 29 July 2019 in Welding in the World
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For the fatigue design of welded structures under constant amplitude loading, often the nominal stress approach based on design S-N curves is used. The design S-N curves, which can be found in commonly used guidelines, cover arc welds as well as beam welds. However, the experimental data basis for the guideline consists mainly of arc-welded joints. Beam-welded components on the other hand show different weld geometries (e.g., weld width, weld enforcement, weld radii) compared with arc-welded components. The local geometry of weldments as well as imperfections can affect the fatigue strength, theoretically in dependence of the ultimate strength. Therefore, the fatigue strength of beam-welded samples in the high cycle fatigue range made from S355J2+N and S960Q was tested in this study. Additionally, the weld geometry of all samples was measured and classified according to the weld quality groups in ISO 13919-1. Furthermore, numerical notch stress calculations were conducted to cover imperfections and weld geometries that were not covered by the experimental investigations. Finally, recommendations for the fatigue resistance of beam-welded butt joints are given. Correlations between the fatigue strength and certain quality groups of selected geometrical features and imperfections are shown.

ACS Style

Ann-Christin Hesse; Jonas Hensel; Thomas Nitschke-Pagel; Klaus Dilger. Investigations on the fatigue strength of beam-welded butt joints taking the weld quality into account. Welding in the World 2019, 63, 1303 -1313.

AMA Style

Ann-Christin Hesse, Jonas Hensel, Thomas Nitschke-Pagel, Klaus Dilger. Investigations on the fatigue strength of beam-welded butt joints taking the weld quality into account. Welding in the World. 2019; 63 (5):1303-1313.

Chicago/Turabian Style

Ann-Christin Hesse; Jonas Hensel; Thomas Nitschke-Pagel; Klaus Dilger. 2019. "Investigations on the fatigue strength of beam-welded butt joints taking the weld quality into account." Welding in the World 63, no. 5: 1303-1313.