TY - RPRT A1 - Behrens, Bernd-Arno A1 - Krimm, Richard A1 - Fries, Stefan A1 - Härtel, Sebastian A1 - Schmidt, Alexander T1 - Eigenschaften individuell gefertigter Bauteile für Umformanlagen N2 - Die Dauerschwingfestigkeit ist eine wichtige sowie für die Auslegung von zyklisch belasteten Bauteilen in Umformmaschinen notwendige Materialkenngröße. Diese Kenngröße ist nicht nur material- sondern auch fertigungsprozessabhängig. Aufgrund der rapiden Entwicklung von additiven Fertigungsanlagen und Werkstoffen mangelt es an hinreichenden Erfahrungswerten zu den Betriebseigenschaften von additiv gefertigten Bauteilen. Daher ist es wichtig, die Eignung von additiv gefertigten Bauteilen für Umformmaschinen im Vorfeld technologisch und wissenschaftlich zu untersuchen. Die Ermittlung der Dauerschwingfestigkeit von additiv gefertigten Komponenten für Umformmaschinen liefert außerdem einen Mehrwert für die konstruktive Auslegung anderer AM-Bauteile mit einem vergleichbaren Belastungskollektiv und ermöglicht eine Topologieoptimierung von Komponenten von Umformmaschinen. Im Rahmen dieses Forschungsvorhabens wurde die Dauerschwingfestigkeit additiv gefertigter Bauteile in Abhängigkeit von der Gesamtheit der Herstellungsparameter eines WAAM-Prozesses sowie diverser Nachbehandlungsmethoden erfolgreich anhand des Fallbeispiels Pleuel ermittelt. Außerdem wurde die Anwendbarkeit von WAAM-Prozessen zur Herstellung von individuellen Anlagenbauteilen für den Bereich Umformmaschinen erfolgreich belegt. Mit den ermittelten Dauerschwingfestigkeitswerten konnte eine Grundlage zur Auslegung weiterer AM-Bauteile mit vergleichbaren Belastungskollektiv sowie Topologieoptimierung genannter Bauteile geschaffen werden. Die Untersuchungen erfolgten an Laborproben geeigneter Geometrie in Bezug auf das Realbauteil und unter Gewährleistung der thermischen Übertragbarkeit auf Realbauteile. Abschließend ist mittels eines skalierten Demonstratorbauteils die Machbarkeit nachgewiesen worden. Y1 - 2023 SN - 978-3-86776-660-9 CY - Hannover ER - TY - GEN A1 - Schmidt, Alexander A1 - Jensch, Felix A1 - Härtel, Sebastian T1 - Multi-material additive manufacturing-functionally graded materials by means of laser remelting during laser powder bed fusion T2 - Frontiers of Mechanical Engineering N2 - Many processes may be used for manufacturing functionally graded materials. Among them, additive manufacturing seems to be predestined due to near-net shape manufacturing of complex geometries combined with the possibility of applying different materials in one component. By adjusting the powder composition of the starting material layer by layer, a macroscopic and step-like gradient can be achieved. To further improve the step-like gradient, an enhancement of the in-situ mixing degree, which is limited according to the state of the art, is necessary. In this paper, a novel technique for an enhancement of the in-situ material mixing degree in the melt pool by applying laser remelting (LR) is described. The effect of layer-wise LR on the formation of the interface was investigated using pure copper and low-alloy steel in a laser powder bed fusion process. Subsequent cross-sectional selective electron microscopic analyses were carried out. By applying LR, the mixing degree was enhanced, and the reaction zone thickness between the materials was increased. Moreover, an additional copper and iron-based phase was formed in the interface, resulting in a smoother gradient of the chemical composition than the case without LR. The Marangoni convection flow and thermal diffusion are the driving forces for the observed effect. KW - multi-material additive manufacturing (MMAM) KW - functionally graded materials (FGMs) KW - laser powder bed fusion (L-PBF) KW - laser remelting (LR) KW - pure copper Y1 - 2023 UR - https://link.springer.com/article/10.1007/s11465-023-0765-z U6 - https://doi.org/10.1007/s11465-023-0765-z SN - 2095-0233 VL - 18 IS - 4 SP - 1 EP - 11 ER - TY - GEN A1 - Alimov, Artem A1 - Sviridov, Alexander A1 - Sydow, Benjamin A1 - Jensch, Felix A1 - Härtel, Sebastian T1 - Additive Manufacturing of Hot-Forming Dies Using Laser Powder Bed Fusion and Wire Arc Direct Energy Deposition Technologies T2 - Metals N2 - Additive technologies are now widely used for the production of complex precise parts and have high potential for the production of forming dies. In this work, hot-forming dies optimized for additive manufacturing were developed and produced with wire arc direct energy deposition (WA-DED) and laser powder bed fusion (L-PBF) technologies. The concept of lightweight hot-forming dies with a 2D-lattice structure was developed, which reduced the weight of each die by 56%, from 14.2 kg to 6.1 kg, in production using L-PBF. Maraging/precipitation-hardened steel 17-4PH was used as an alternative to traditional hot-working steels with slightly lower mechanical properties and a much higher processability in the additive manufacturing process. The workability of the manufactured dies was confirmed by forging tests on an industrial screw press. KW - additive manufacturing KW - hot-forming dies KW - L-PBF KW - WA-DED KW - WAAM Y1 - 2023 UR - https://www.mdpi.com/2075-4701/13/11/1842 U6 - https://doi.org/10.3390/met13111842 SN - 2075-4701 VL - 13 IS - 11 ER - TY - GEN A1 - Jäger, Reyk A1 - Sydow, Benjamin A1 - Schmidt, Alexander A1 - Witt, Susanne A1 - Härtel, Sebastian ED - Mocellin, Katia T1 - Design and Manufacturing of a Lightweight Press-Hardening Forming Tool by Wire Arc Additive Manufacturing T2 - Proceedings of the 14th International Conference on the Technology of Plasticity - Current Trends in the Technology of Plasticity, Volume 3 N2 - Press-hardening is an important metal sheet manufacturing process to improve the metal sheet properties during forming with an inline quenching process. This requires higher cooling rates often obtained by cooling channels within the tools, that enable the formation of martensite for a high strength. The manufacturing of those forming tools with internal cooling channels is quite complex, time and material consuming and therefore expensive. Optimal cooling channel geometry cannot be realized by conventional machining operations, that limits cooling efficiency too. Wire Arc Additive Manufacturing (WAAM) is a layer-wise welding process, that allows the manufacturing of near net shapes and internal cooling channels. In contrast to conventional machining, manufacturing of a complex lightweight design forming tool can be realized by WAAM. This will further reduce the WAAM process time and material consumption. However, the lightweight design reduces on one hand the thermal mass and thus the capability of heat transfer, making cooling via the cooling channels more crucial. On the other hand, elastic tool deformation has to be as low as possible. In this study, a press-hardening forming tool made of S235JR is designed and manufactured by means of WAAM. FEM analysis are performed to optimize the design of the forming tool regarding lightweight aspects. Simple near net shapes of cooling channels are considered for a simplification of the WAAM process. The forming tool is mechanically tested to compare and evaluate the stiffness with the FEM analysis. KW - lightweight forming tool KW - press-hardening KW - wire arc additive manufacturing KW - integrated surface cooling KW - CO2 balance Y1 - 2023 SN - 978-3-031-41340-7 SN - 978-3-031-41341-4 U6 - https://doi.org/10.1007/978-3-031-41341-4_25 SN - 2195-4364 SP - 235 EP - 246 PB - Springer ER - TY - GEN A1 - Neumann, Andreas A1 - Härtel, Sebastian ED - Mocellin, Katia T1 - Limitations of a new forming process for vault structured recuperator tubes T2 - Proceedings of the 14th International Conference on the Technology of Plasticity - Current Trends in the Technology of Plasticity ICTP 2023 - Volume 1 N2 - Classic forming technologies can make a difference to a climate-neutral economy. This also applies to the production of innovative hydrogen coolers (recuperators). To improve the efficiency of hydrogen coolers, heat transfer and heat flux can be increased by tube structures made by pressing spherical elements on their surface. Hydrogen is passed through the tubes of the recuperators and the cooling medium flows across it (Figure 1a). The tube serves as an atmosphere separator. Structured tubes can increase the power den-sity with the same dimensions. Figure 1b shows a process for introducing the structure into the pipe using radially and symmetrically arranged tools. Sheet metal forming usually involves pressing with structural tools, bending into a tube, and longitudinally welding. However, producing small tube diameters in the range of one inch presents a technical challenge. The challenge considered in this paper is to develop a new structuring process while maintaining the structural integrity and wall thickness of the tubes. This study aims to determine the feasibility of a multi-stage vault structuring process for recuperator tubes us-ing heat-resistant semi-finished products. KW - Forming limit, model-based evaluation, Tool Development Y1 - 2023 SN - 978-3-031-41022-2 U6 - https://doi.org/10.1007/978-3-031-41023-9_58 SN - 2195-4356 SP - 577 EP - 583 PB - Springer Nature CY - Cham, Schweiz ET - 1 ER - TY - GEN A1 - Jhanji, Avantika A1 - Sydow, Benjamin A1 - Adams, Tom-Eric A1 - Habisch, Stefan A1 - Härtel, Sebastian T1 - Influence of the Initial Microstructure on the Mechanical Behavior During Forming for Inline Manufacturing Process Routes T2 - Proceedings of the 14th International Conference on the Technology of Plasticity - Current Trends in the Technology of Plasticity, ICTP 2023 - Volume 2 N2 - With a view of sustainability and the rising energy costs currently, manufacturing processes of metals are becoming increasingly focused on optimizing process parameters such as energy and time consumption. A conventional hot-forming process route currently involves casting an ingot, letting it cool down, and heating it up again for the hot-forming process (see Fig. 1a). In order to implement the combination of casting and forging, avoiding the reheating cycle and using less energy, by utilizing the casting heat (see Fig. 1b), a methodology was developed within the present work to quantify the influence of the resulting microstructure as a function of the cooling rate on the forming and recrystallization behavior (see Fig. 1c). For this purpose, AISI 301 austenitic stainless-steel cast samples with different cast cooling rates were generated. An in-situ high-temperature microscope is used to determine the holding time and the heating rate. Dilatometer tests are performed to characterize the interaction between initial microstructure and the flow curves to verify the determination method (see Fig. 1d). The aim was to demonstrate whether the microstructure evolution and mechanical behavior is affected by the initial microstructure. The flow curves and the post-forming microstructure show a higher degree of recrystallization in fast-cooled microstructure than slow-cooled microstructure. Hence, it was found that the initial microstructure and the associated temperature history does have an impact on the mechanical properties. Y1 - 2023 SN - 978-3-031-40919-6 SN - 978-3-031-40920-2 U6 - https://doi.org/10.1007/978-3-031-40920-2_53 SN - 2195-4356 SP - 513 EP - 524 PB - Springer Nature Switzerland CY - Cham ER - TY - GEN A1 - Graf, Marcel A1 - Pippig, Robert A1 - Lehnert, Tim A1 - Jedynak, Angelika A1 - Härtel, Sebastian ED - Mocellin, Katia T1 - Aluminium-Matrix-Composites (AMC) for Hot Forged Components T2 - Proceedings of the 14th International Conference on the Technology of Plasticity - Current Trends in the Technology of Plasticity, ICTP 2023 - Volume 1 N2 - The development of new materials or material systems is always accompanied by the development of processing technologies suitable for the material. The reduction of process steps, the saving of material and the optimization of material properties are aims of forming processes. The basis for this is the comprehensive characterisation of the thermos-physical and thermos-mechanical technologically relevant material behaviour, taking into account the real process conditions. In the present work, the material-specific process limits were determined by means of experimental simulation and used in the numerical simulation in order, on the one hand, to identify the forming steps for optimizing the manufacturing conditions and, on the other hand, to be able to set the final material properties. It was essential to homogenize the casting microstructure for the forming processes and to adjust it to globulitical grains by solution annealing. The previously limited forming behaviour of the cast AlSi9Mg alloy with 20 vol.-% SiC could be increased thus to forging-relevant plastic strains without occurring damages. Based on the comprehensive temperature-dependent material data, a one-step and resource-efficient manufacturing process for AMC materials by hot forming could be developed with the help of the FE software Simufact Forming and validated in reality under near-industrial conditions. Y1 - 2023 SN - 978-3-031-41022-2 SN - 978-3-031-41023-9 U6 - https://doi.org/10.1007/978-3-031-41023-9_4 SN - 2195-4356 SP - 36 EP - 47 PB - Springer Nature Switzerland CY - Cham ER - TY - GEN A1 - Buhl, Johannes A1 - Härtel, Sebastian A1 - Besong, Lemopi Isidore ED - Mocellin, Katia T1 - Temperature Control of the Two-Point Incremental Forming Process to Achieve Homogeneous Martensite Content Based on Finite Element Simulations T2 - Proceedings of the 14th International Conference on the Technology of Plasticity - Current Trends in the Technology of Plasticity, ICTP 2023 - Volume 1 N2 - Deformation-induced martensite has been observed in the incremental sheet forming of metastable austenitic stainless steels (MASS). The presence of martensite improves the characteristics of the springs. Martensite transformation usually occurs at low temperatures (<70 ℃). Depending on the tool speed, incremental forming of disk springs requires between 3 to 5 min. The forming time needs to be short to increase the process output in industrial settings. However, accelerating the process leads to high temperatures above the martensite transformation temperature that suppress martensite formation, necessitating temperature control during forming. It is suggested to enhance the martensite content of the blank by cooling during the forming operation. In this contribution, two-point incremental sheet forming is conducted to determine the influence of process temperature on the phase content of MASS disk springs. A temperature-dependent phase change material model that includes the strain rate effect is implemented in finite element (FE) simulations to predict the martensite content. FE simulations are performed to investigate the convection coefficients and cooling time leading to process temperatures below 70 ℃. The framework can be used to control and speed up the incremental forming of disk springs while maintaining a high martensite content. Y1 - 2023 SN - 978-3-031-41022-2 SN - 978-3-031-41023-9 U6 - https://doi.org/10.1007/978-3-031-41023-9_74 SN - 2195-4356 SP - 739 EP - 747 PB - Springer CY - Cham ER - TY - GEN A1 - Szyndler, Joanna A1 - Härtel, Sebastian A1 - Bambach, Markus T1 - Machine learning of the dynamics of strain hardening based on contact transformations T2 - Journal of Intelligent Manufacturing N2 - Dislocation density-based models offer a physically grounded approach to modeling strain hardening in metal forming. Since these models are typically defined by Ordinary Differential Equations (ODEs), their accuracy is constrained by both, the model formulation and the parameter identification process. Machine Learning (ML) provides an alternative by allowing models to be constructed directly from experimental data, bypassing the accuracy limitations of explicitly defined models. However, applying ML to ODEs introduces the need for novel training techniques. This work presents a new approach for developing neural ODE models for flow curve description, utilizing a contact transformation to simplify the problem of learning an ODE into a learning a multivariate function. Y1 - 2025 UR - https://link.springer.com/article/10.1007/s10845-025-02577-6 U6 - https://doi.org/10.1007/s10845-025-02577-6 VL - 2025 PB - Springer ER - TY - GEN A1 - Grüger, Lennart A1 - Szyndler, Joanna A1 - Jensch, Felix A1 - Härtel, Sebastian T1 - Porosity analysis of L-PBF manufactured AZ91D components T2 - Materials research proceedings N2 - Several materials for joint replacement parts approved in medical technology are being investigated. Magnesium alloys are very suitable for implants due to the similar strength properties between magnesium alloys and human bone. Therefore, the present work aims to examine the parameters for producing the magnesium alloy AZ91D. For this purpose, 16 samples were manufactured with varying laser power and exposure speed and examined using µCT analyses. As a result, densities between 99.56 and 95.21 percent were achieved. The samples with the lowest density were subjected to a HIP process to increase the relative density. However, a further µCT analysis revealed only minor positive effects of the HIP process. An analysis of the number and size of the pores indicates that the pores bonded together instead of being closed. KW - A91D KW - Additive Manufacturing KW - L-PBF KW - HIP KW - Process Parameter Analysis Y1 - 2025 SN - 978-1-64490-359-9 U6 - https://doi.org/10.21741/9781644903599-22 SN - 2474-395X VL - 54 SP - 199 EP - 208 PB - Materials Research Forum LLC CY - Millersville, PA ER - TY - GEN A1 - Sviridov, Alexander A1 - Alimov, Artem A1 - Jensch, Felix A1 - Dubinin, Sergej A1 - Härtel, Sebastian T1 - Influence of surface quality on performance of forging dies produced by additive manufacturing the role of post-processing in LPBF-manufactured X55 steel T2 - Materials research proceedings N2 - Laser Powder Bed Fusion (LPBF) has become a key technology in additive manufacturing (AM), enabling the production of highly complex geometries and is increasingly applied in serial production. With the continuous expansion of processable materials, LPBF is now also being considered for the manufacturing of forging dies. However, LPBF application for tool steels such as H11 is limited by their susceptibility to hot cracking. Maraging steels like X55 present a promising alternative due to their superior resistance to such defects. A major advantage of this technology for forging dies lies in the potential elimination of extensive machining required to refine rough as-built surfaces, thereby streamlining and accelerating the production process. Achieving this goal requires systematic investigations into non-machining post-processing techniques for targeted surface modifications, along with a comprehensive evaluation of mechanical properties and surface integrity after post-processing. This study examines the influence of different post-processing methods on the surface quality, mechanical properties, and tribological behavior of LPBF-manufactured X55 (1.2709) specimens. To evaluate surface roughness and mechanical performance, slope specimens and tensile specimens were analyzed in different conditions: as-built, mechanically machined, sandblasted, and treated via Hirtisition®. Additionally, flat dies were produced and subjected to ring compression tests to determine friction factors under varying surface and lubrication conditions. The findings emphasize the crucial role of post-processing in optimizing the surface quality and functional performance of LPBF-manufactured forging tools, offering valuable insights for their further development. KW - Additive manufacturing KW - L-PBF KW - Forging dies KW - Hot bulk forging KW - Friction KW - X55 Y1 - 2025 SN - 978-1-64490-359-9 U6 - https://doi.org/10.21741/9781644903599-27 SN - 2474-395X VL - 54 SP - 245 EP - 253 PB - Materials Research Forum LLC CY - Millersville, PA ER -