Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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Historical Paper Documents

2023 , Rögner, Frank-Holm , Schottner, Gerhard , Grählert, Wulf , Gruber, Florian , Fuchs, Theobald , Hügle, Johannes

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Retaining Mechanical Properties of GMA-Welded Joints of 9%Ni Steel Using Experimentally Produced Matching Ferritic Filler Metal

2022-11-30 , El-batahgy, Abdel-monem , Elkousy, Mohamed Raafat , Al-Rahman, Ahmed Abd , Gumenyuk, Andrey , Rethmeier, Michael , Gook, Sergej

Motivated by the loss of tensile strength in 9%Ni steel arc-welded joints performed using commercially available Ni-based austenitic filler metals, the viability of retaining tensile strength using an experimentally produced matching ferritic filler metal was confirmed. Compared to the austenitic Ni-based filler metal (685 MPa), higher tensile strength in gas metal arc (GMA) welded joints was achieved using a ferritic filler metal (749 MPa) due to its microstructure being similar to the base metal (645 MPa). The microstructure of hard martensite resulted in an impact energy of 71 J (−196 °C), which was two times higher than the specified minimum value of ≥34 J. The tensile and impact strength of the welded joint is affected not only by its microstructure, but also by the degree of its mechanical mismatch depending on the type of filler metal. Welds with a harder microstructure and less mechanical mismatch are important for achieving an adequate combination of tensile strength and notched impact strength. This is achievable with the cost-effective ferritic filler metal. A more desirable combination of mechanical properties is guaranteed by applying low preheating temperature (200 °C), which is a more practicable and economical solution compared to the high post-weld heat treatment (PWHT) temperature (580 °C) suggested by other research.

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Untersuchung zum Elektronenstrahlschweißen additiv gefertigter Ni-Basis-Bauteile

2022-10-26 , Raute, Maximilian Julius , Marquardt, Raphael , Biegler, Max , Rethmeier, Michael

Die vorliegende Untersuchung befasst sich mit dem Einfluss des Additive Manufacturing auf die Schweißeignung von Bauteilen aus Inconel 718. Hierfür wurden Proben mittels DED und L-PBF hergestellt und ihr Verhalten in Blindschweißversuchen anhand eines Vergleichs mit konventionellen Gussblechen untersucht. Im zweiten Schritt wurden die verschiedenen additiv hergestellten Proben mit dem Gussmaterial im I-Stoß sowie untereinander verschweißt. Als Schweißverfahren wurde für alle Proben das Elektronenstrahlschweißen angewandt. Zur Auswertung wurde anhand von Schliffen das Nahtprofil vermessen und die Proben auf Poren und Risse untersucht. Zusätzlich wurde die Dichte vermessen und eine Prüfung auf Oberflächenrisse durchgeführt. Das AM-Material zeigte dabei Unterschiede in Nahtform und Defektneigung im Vergleich zum Gusswerkstoff. Insbesondere die DED-proben neigten unter bestimmten Parameterkonstellationen verstärkt zu Porenbildung. Risse konnten nicht beobachtet werden. Trotz auftretender Nahtunregelmäßigkeiten wurde in den kombinierten AM-Schweißproben die Bewertungsgruppe C erreicht. Eine Prüfung der bestehenden Regelwerke zur Schweißnahtbewertung anhand der gewonnenen Erkenntnisse zu additiv gefertigten Proben im Elektronenstrahlschweißprozess zeigte keinen Ergänzungsbedarf.

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Result quality evaluation of Directed Energy Deposition Additive Manufacturing simulations with progressive simplification of transient heat-source motion

2022-09-05 , Biegler, Max , Elsner, Beatrix A.M. , Neubauer, Ingo , Lemke, Josefine , Rethmeier, Michael

Directed Energy Deposition (DED) additive manufacturing has recently been adopted in the industry for the build-up of structural components with weld lengths up to kilometers. As with all welding processes, DED suffers from thermal distortion, causing loss of dimensional accuracy and risk of cracking. Currently, process optimization with objective to minimize distortion requires expensive experimental trial-and-error. With numerical simulation of the DED process, this distortion compensation can be performed virtually, significantly reducing experimental trials. Although such approaches are generally available, their widespread adoption is currently being hampered by long computational times for large builds. This work presents a novel approach to reduce the calculation time by a simplification of the transient heat-source motion. This approach is assessed in terms of result accuracy for an industrial-scale component by progressively reducing the resolution of the heat-source motion. Calculation times as well as distortions in comparison to experimental trials are investigated.

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Fraunhofer Technologies for Heritage Protection in Times of Climate Change and Digitization

2023 , Pollmer, Uta

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Additive Fertigung von Funktional Gradierten Materialien für den Verschleißschutz

2022-11-07 , Marquardt, Raphael

Das Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik in Berlin erforscht die Additive Fertigung von Funktional Gradierten Materialien für Verschleiß- und Korrosionsschutzanwendungen. Damit können Bauteile mit maßgeschneiderten Eigenschaften und verbesserter Lebensdauer vollständig additiv aufgebaut oder auch nachträglich gepanzert werden.

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Prognose von Qualitätsmerkmalen durch Anwendung von KI-Methoden beim "Directed Energy Deposition"

2022-10 , Marko, Angelina , Bähring, Stefan , Raute, Maximilian Julius , Biegler, Max , Rethmeier, Michael

Dieser Beitrag enthält die Ergebnisse eines im Rahmen der DVS Forschung entwickelten Ansatzes zur Qualitätssicherung im Directed Energy Deposition. Es basiert auf der Verarbeitung verschiedener während des Prozesses gesammelter Sensordaten unter Anwendung Künstlicher Neuronale Netze (KNN). So ließen sich die Qualitätsmerkmale Härte und Dichte auf der Datenbasis von 50 additiv gefertigten Probenwürfel mit einer Abweichung < 2 % vorhersagen. Des Weiteren wurde die Übertragbarkeit des KNN auf eine Schaufelgeometrie untersucht. Auch hier ließen sich Härte und Dichte hervorragend prognostizieren (Abweichung < 1,5 %), sodass der Ansatz als validiert betrachtet werden kann.

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Mittels Scangineering und Schweiß-Knowhow zum reparierten Umformwerkzeug

2022-12-19 , Biegler, Max , Mönchinger, Stephan , Müller, Vinzenz , Rethmeier, Michael

Zum wirtschaftlichen und nachhaltigen Einsatz von Stanz- und Formwerkzeugen ist in der Regel eine Reparatur der verschlissenen Werkzeuge erforderlich. Das Additive Fertigungsverfahren Laser-Powder Directed Energy Depositon (LP-DED) in Kombinationen mit intelligenten Reverse-Engineering-Ansätzen bietet die Möglichkeit, Bauteile materialschonend und effizient zu reparieren.

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Transferability of ANN-generated parameter sets from welding tracks to 3D-geometries in Directed Energy Deposition

2022-11-04 , Marko, Angelina , Bähring, Stefan , Raute, Maximilian Julius , Biegler, Max , Rethmeier, Michael

Directed energy deposition (DED) has been in industrial use as a coating process for many years. Modern applications include the repair of existing components and additive manufacturing. The main advantages of DED are high deposition rates and low energy input. However, the process is influenced by a variety of parameters affecting the component quality. Artificial neural networks (ANNs) offer the possibility of mapping complex processes such as DED. They can serve as a tool for predicting optimal process parameters and quality characteristics. Previous research only refers to weld beads: a transferability to additively manufactured three-dimensional components has not been investigated. In the context of this work, an ANN is generated based on 86 weld beads. Quality categories (poor, medium, and good) are chosen as target variables to combine several quality features. The applicability of this categorization compared to conventional characteristics is discussed in detail. The ANN predicts the quality category of weld beads with an average accuracy of 81.5%. Two randomly generated parameter sets predicted as “good” by the network are then used to build tracks, coatings, walls, and cubes. It is shown that ANN trained with weld beads are suitable for complex parameter predictions in a limited way.

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Resource efficient production of car body parts - implementation of digital twins across process chains

2022-09-21 , Weber, Joshua , Lemke, Josefine , Sunderkoetter, Christina , Haase, Patrick , Hoefemann, Matthias , Joos, Paul , Merklein, Marion

Sustainable production and environmentally friendly life cycle of every car is a main goal in the automotive industry. But there is a conflict between the rising demands of crash safety, the addition of components due to electric mobility and the reduction of weight. Car body parts can increase the crash safety and have a high lightweight construction potential. Especially tailor welded blanks made of multi-phase steel with a tensile strength of 1000 MPa, which are not established in car body parts, have the potential to improve the crash safety, save resources and lower the weight. The main challenge in the manufacturing of tailor welded blanks made of highest strength steel is the complex and expensive development. Due to the heat input and geometrical changes, the welding process affects the forming properties of the metal sheets. To evaluate the influence from different welding parameters to the forming process, a high number of expensive experiments must be repeated. This includes welding and forming parameter changes as well as adjustments to the forming tool. In order to make the development and manufacturing of tailor welded blanks made of highest strength steels more resource efficient, this work discusses the development and implementation of a digital and bidirectional twin in an industry-oriented environment. The objective is to demonstrate the data management based on the sheet metal properties, the change of properties due to laser welding simulated in Simufact Welding and the final forming process in AutoForm Forming. Additionally, the concept of a life cycle assessment of a tailor welded blank during these steps is developed. As summary the challenges, limitations, and improvements of the digital and bidirectional twin as replacement or, in addition to a consisting development process are discussed.

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