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Microstructure of Inconel 718 parts with constant mass energy input manufactured with direct energy deposition

Procedia Manufacturing 2019年 36卷 256-266页

作者： Torsten Petrat Christian Brunner-Schwer Benjamin Graf Michael Rethmeier Fraunhofer Institut for Production Systems and Design Technology Pascalstraße 8-9 10587 Berlin Germany Federal Institute for Materials Research and Testing Unter den Eichen 87 12205 Berlin Germany Technical University Berlin Institute of Machine Tools and Factory Management Pascalstraße 8-9 10587 Berlin Germany

The laser-based direct energy deposition (DED) as a technology for additive manufacturing allows the production of near net shape components. Industrial applications require a stable process to ensure reproducible quality. Instabilities in the manufacturing process can lead to faulty components which do not meet the required properties. The DED process is adjusted by various parameters such as laser power, velocity, powder mass flow and spot diameter, which interact with each other. A frequently used comparative parameter in welding is the energy per unit length and is calculated from the laser power and the velocity in laser welding. The powder per unit length comparative parameter in the DED process has also be considered, because this filler material absorbs energy in addition to the base material. This paper deals with the influence of mass energy as a comparative parameter for determining the properties of additively manufactured parts. The same energy per unit length of 60 J/mm as well as the same powder per unit length of 7.2 mg/mm can be adjusted with different parameter sets. The energy per unit length and the powder per unit length determine the mass energy. The laser power is varied within the experiments between 400 W and 900 W. Energy per unit length and powder per unit length are kept constant by adjusting velocity and powder mass flow. Using the example of Inconel 718, experiments are carried out with the determined parameter sets. In a first step, individual tracks are produced and analyzed by means of micro section. The geometry of the tracks shows differences in height and width. In addition, the increasing laser power leads to a higher dilution of the base material. To determine the suitability of the parameters for additive manufacturing use, the individual tracks are used to build up parts with a square base area of 20×20 mm². An investigation by Archimedean principle shows a higher porosity with lower laser power. By further analysis of the mic

关键词： direct energy deposition porosity Inconel 718 additive manufacturing laser metal deposition

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Biomechanical validation of additively manufactured artificial femoral bones

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BMC biomedical engineering 2022年第1期4卷 6页

作者： F Metzner C Neupetsch A Carabello M Pietsch T Wendler W-G Drossel ZESBO Centre for Research on Musculoskeletal Systems Leipzig University Semmelweisstraße 14 04103 Leipzig Germany. florian.metzner@medizin.uni-leipzig.de. Department of Orthopaedics Trauma and Plastic Surgery Leipzig University Leipzig Germany. florian.metzner@medizin.uni-leipzig.de. Department of Orthopaedics Trauma and Plastic Surgery Leipzig University Leipzig Germany. Fraunhofer Institute for Machine Tools and Forming Technology Dresden Germany. Professorship of Adaptronics and Lightweight Design Chemnitz Universtiy of Technology Chemnitz Germany. ZESBO Centre for Research on Musculoskeletal Systems Leipzig University Semmelweisstraße 14 04103 Leipzig Germany.

Replicating the mechanical behavior of human bones, especially cancellous bone tissue, is challenging. Typically, conventional bone models primarily consist of polyurethane foam surrounded by a solid shell. Although nearly isotropic foam components have mechanical properties similar to cancellous bone, they do not represent the anisotropy and inhomogeneity of bone architecture. To consider the architecture of bone, models were developed whose core was additively manufactured based on CT data. This core was subsequently coated with glass fiber composite. Specimens consisting of a gyroid-structure were fabricated using fused filament fabrication (FFF) techniques from different materials and various filler levels. Subsequent compression tests showed good accordance between the mechanical behavior of the printed specimens and human bone. The unidirectional fiberglass composite showed higher strength and stiffness than human cortical bone in 3-point bending tests, with comparable material behaviors being observed. During biomechanical investigation of the entire assembly, femoral prosthetic stems were inserted into both artificial and human bones under controlled conditions, while recording occurring forces and strains. All of the artificial prototypes, made of different materials, showed analogous behavior to human bone. In conclusion, it was shown that low-cost FFF technique can be used to generate valid bone models and selectively modify their properties by changing the infill.

关键词： 3D-printing 3d-printing Additive manufacturing Artificial bone Biomechanics Bone model Femoral Femur Hip

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Considering Energy-Related Factors in the Simulation of Logistics Systems

Considering Energy-Related Factors in the Simulation of Logi...

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Simulation Winter Conference

作者： Moritz Poeting Bastian Prell Markus Rabe Tobias Uhlig Sigrid Wenzel Institute of Transport Logistics TU Dortmund University Dortmund GERMANY Department Factory of the Future Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz GERMANY Department IT in Production and Logistics TU Dortmund University Dortmund GERMANY Department of Computer Science Universität der Bundeswehr München Neubiberg GERMANY Department of Organization of Production and Factory Planning University of Kassel Kassel GERMANY

ISBN: (数字)9781728132839

ISBN: (纸本)9781728120522

Traditionally, aspects such as emissions and energy consumption have to be taken into account for environmental and economic reasons when it comes to transport. In other areas of logistics, such as production logistics and intralogistics, the energy aspect is also becoming increasingly important. Existing literature has been recently reviewed in a contribution of the Arbeitsgemeinschaft Simulation (ASIM) to the Winter Simulation Conference 2018 (Uhlig et al. 2018) to develop a map of common approaches and best practices for manufacturing and logistics systems. In the paper presented here, as a complement we are focusing on the application of energy simulation in logistics to give a comprehensive overview and present exemplary case studies. Furthermore, we show a classification of approaches to combine energy aspects with simulation. Finally, we will discuss open questions and future trends in this field of research.

关键词： tools Mathematical model Supply chains Matlab Adaptation models

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Process optimization for flexible self-pierce riveting of multi-material structures

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AIP Conference Proceedings 2019年第1期2113卷

作者： Tobias Falk Mathias Jäckel 1Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 01187 Dresden Germany

One of the most important mechanical joining technologies for mixed-material car body constructions is self-pierce riveting with semi-tubular rivet (SPR-ST). In order to achieve appropriate joint quality for SPR-ST, it is often necessary to use individual process parameters like die geometry or rivet length for each material and thickness combination. In this paper a method is presented, that allows to increase the flexibility of the SPR-ST process by an optimization of process parameters in regard to join several material combinations with one die geometry. Thereby FEM simulation is combined with statistical approaches to develop an optimized SPR-ST process.

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A New Systematic Approach to the Description of Processes and their Classification

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Procedia Manufacturing 2017年 8卷 199-206页

作者： Alexandr, P. Kuznetsov Hans-Joachim, Koriath Moscow State University of Technology “STANKIN” Moscow 127055 Russian Federation Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz 09126 Germany

Technical systems change their states and relations between elements during the transformation of energy, matter and information. Paper develops a new systematic approach to the description of processes and their classification, completed by a general description of systems. Systemic transformation categories of typical processes are proposed and applied for an energetic-informational model. Functional relations between categories, transformations and parameters of processes are developed for their classification and digital evaluation. The number of processes that may be formed by the elements of the system is determined by the number of combinations. The proposed general energy-information model of manufacturing processes and new classification will initiate progressive research and development activities on manufacturing processes and associated technologies, the evaluation of increased technological competitiveness, the strategic trend scouting, the optimization of manufacturing processes. © 2017 The Authors

关键词： energy information machine manufacturing matter process

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Parameter Measurement and Conductive Heating During Press Hardening by Hot Metal Gas forming

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IOP Conference Series: Materials Science and Engineering 2019年第1期651卷

作者： M Bach L Degenkolb F Reuther V Psyk R Mauermann M Werner Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany Salzgitter Hydroforming GmbH & Co. KG Crimmitschau Germany

Press hardening of steels for the production of car body components is very common. The reason for this is that the process allows the use of blanks with low wall thickness and the production of ultra-high strength components with complex geometries. The Hot Metal Gas forming (HMGF) process for closed profiles combines the advantages of hydroforming, such as increased rigidity, functional integration or elimination of joining operations, with those of press hardening. In this paper results of continuous tests with actively cooled tools are presented in combination with temperature and displacement measurement. Furthermore, test results for HMGF with tool integrated conductive heating are demonstrated. Tests were done with tube material PHS1800 by SSAB, part temperatures over the Point of austenitisation and maximum internal pressure of 70 MPa. Thermocouples recorded the heat distribution in the tools. Other measured and recorded variables were the displacement of the component wall while forming under increasing internal pressure by a tactile displacement sensor and simultaneous temperature of its surface with a thermal sensor head. For the first time, information on pressure, the corresponding deformation stage and temperature profile could be documented during an entire forming step. A close to series production geometry DP4 was used to investigate the tool-integrated conductive heating of components.

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Technologies for the mechanical joining of aluminum die castings

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AIP Conference Proceedings 2019年第1期2113卷

作者： Thomas Grimm Mathias Jäckel Tobias Falk Welf-Guntram Drossel 1Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 01187 Dresden Germany

This paper shows a comparison of existing self-pierce riveting technologies with the newly developed self-pierce riveting with solid formable rivet (SPR-SF) for the joining of Aluminum die casts. The challenges during the mechanical joining of the Aluminum die cast AlSi9Mn by different joining technologies like self-pierce riveting with semi-tubular rivet (SPR-ST), self-pierce riveting with moveable die element and semi-tubular rivet (S-SPR-ST), self-pierce riveting with solid rivet (SPR-S) and self-pierce riveting with solid formable rivet (SPR-SF) will be discussed and the joining technologies in regard to process force, interlock, shear tensile strength and top tensile strength will be analyzed.

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Influence of an external applied AC magnetic field on the melt pool dynamics at high-power laser beam welding

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IOP Conference Series: Materials Science and Engineering 2021年第1期1135卷

作者： Ömer Üstündağ Nasim Bakir Andrey Gumenyuk Michael Rethmeier Bundesanstalt für Materialforschung und -prüfung (BAM) Unter den Eichen 87 12205 Berlin Germany Fraunhofer Institute for Production Systems and Design Technology Pascalstraße 8-9 10587 Berlin Germany Institute for Machine Tools and Factory Management Technische Universität Berlin Pascalstraße 8-9 10587 Berlin Germany

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.

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The bulging effect and its relevance in high power laser beam welding

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IOP Conference Series: Materials Science and Engineering 2021年第1期1135卷

作者： Antoni Artinov Xiangmeng Meng Nasim Bakir Ömer Üstündağ Marcel Bachmann Andrey Gumenyuk Michael Rethmeier Bundesanstalt für Materialforschung und -prüfung (BAM) Unter den Eichen 87 12205 Berlin Germany Fraunhofer Institute for Production Systems and Design Technology Pascalstraße 8-9 10587 Berlin Germany Institute for Machine Tools and Factory Management Technische Universität Berlin Pascalstraße 8-9 10587 Berlin Germany

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 an infrared camera 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 more frequently during partial penetration above 6 mm and complete penetration above 8 mm penetration depth, respectively. 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.

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Investigation of the gap bridgeability at high-power laser hybrid welding of plasma-cut thick mild steels with AC magnetic support

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Journal of Physics: Conference Series 2021年第1期2077卷

作者： Ömer Üstündag Nasim Bakir Andrey Gumenyuk Michael Rethmeier Bundesanstalt für Materialforschung und -prüfung (BAM) Unter den Eichen 87 12205 Berlin Germany Fraunhofer Institute for Production Systems and Design Technology Pascalstraße 8-9 10587 Berlin Germany Institute of Machine Tools and Factory Management Technische Universität Berlin Pascalstraße 8-9 10587 Berlin Germany

One of the challenges of the high-power hybrid laser welding of thick steels is the sensitivity of the process of the process to manufacturing tolerances. This usually leads to a time-consuming preparation of the welding edges, such as milling. The study deals with the influence of the edge quality of milled and plasma-cut steel made of S355J2 with a wall thickness of 20 mm on the laser hybrid welded seam quality. Furthermore, the gap bridgeability and the tolerances towards edge misalignment was investigated. An AC magnet was used as backing support to prevent sagging and positioned under the workpiece, to generate an upwards directed electromagnetic pressure. The profiles of the edges and the gap on the top and root side were measured using a digital camera. Single-pass laser hybrid welds of plasma-cut edges could be welded using a laser beam power of just 13.7 kW. A gap bridgeability up to 2 mm and misalignment of edges up to 2 mm could be achieved successful. Additionally, the independence of the cutting side and the welding side was shown, so that samples were welded to the opposite side to their cutting. For evaluation of internal defects or irregularities, X-ray images were carried out. Charpy impact strength tests were performed to determine the toughness of the welds.

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