Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-44604 Beitrag zu einem Tagungsband Rockenhäuser, Christian; von Hartrott, P.; Metzger, M.; Schriever, Sina; Augenstein, E.; Karlin, J.; Piesker, Benjamin; Schweizer, Ch.; Skrotzki, Birgit Lebensdauerberechnung von Aluminium-Radialverdichterrädern unter Berücksichtigung der Werkstoffalterung In this project, a procedure was developed to improve the lifetime assessment precision of exhaust turbo charger radial compressor wheels made from the age hardenable aluminum alloy EN AW-2618A. This comprises particularly the consideration of material aging, which has to be anticipated during operation of such components under relevant service conditions (temperature, time, stress). First of all, a solid experimental database was established for the investigated material. This includes a mechanical as well as a microstructural characterization of the as-received state (T61) and after aging up to 25,000 h at relevant service temperatures (160 °C, 180 °C, 190 °C). The microstructural investigations focused on the development of the radii of the cylindrical hardening phase, which coarsens during aging. The relation between aging temperature, time and mechanical load (if applicable) was established for the first time to this extent. An interrelationship to describe the coarsening was established. The effect of aging on hardness, strength, creep behavior and fatigue lifetime (LCF, TMF) was studied and a correlation to the microstructure was established. The results of the creep tests were used to calibrate a modified hyperbolic sine creep model. A time and temperature dependent deformation model according to Chaboche, which describes the relevant phenomena of high temperature deformation and cyclic plasticity, was extended. It now considers material aging by describing the strength not only as a function of temperature but also as a function of aging, i.e. of the mean radius of the precipitates. A similar procedure was applied to extend the model in order to assess the fatigue lifetime. The calculated lifetimes of LCF and TMF tests completed during this project match well with the experimental results. Only one LCF test with a hold time of 900 s in tension deviates clearly from the mean value and shows the limits of the time independent damage model. Tests with shorter hold times of 60 s are within the scatter band, likewise the different aging conditions. A damage accumulation model additionally describing the progressive aging during lifetime was developed and implemented. Besides considering aging in the deformation and lifetime assessment, it is also possible to judge complex loading cycles in a postprocessing by rain flow classification of typical complex loading cycles. The methodology and the models were implemented into the Finite-Element software Abaqus and Ansys and are available for numerical assessment of components. 2018 Tagungsband R583 FVV Frühjahrstagung 2018 FVV Frühjahrstagung 2018 Bad Neuenahr, Germany 22.03.2018 97 130 2018-04-04 OPUS4-45284 Beitrag zu einem Tagungsband von Hartrott, P.; Rockenhäuser, Christian; Schriever, Sina; Skrotzki, Birgit Correlation of the precipitate size evolution and the creep rate of the aluminium alloy EN AW 2618A at 190 °C A short description of the work done on the topic "Correlation of the precipitate size evolution and the creep rate of the aluminium alloy EN AW 2618A at 190 °C" is given. 2018 Proceedings of the International Conference on Aluminium Alloys 16 978-1-926872-41-4 International Conference on Aluminium Alloys 16 Montreal, Canada 17.06.2018 99 2018-07-09 OPUS4-45287 Beitrag zu einem Tagungsband Rockenhäuser, Christian; Augenstein, E.; Skrotzki, Birgit Long term ageing of alloy 2618A The result of an Investigation of the "Long term ageing of alloy 2618A" are discussed. 2018 Proceedings of the International Conference on Aluminium Alloys 16 International Conference on Aluminium Alloys 16 Montreal, Canada 17.06.2018 Paper 400101 2018-06-26 OPUS4-45288 Vortrag Rockenhäuser, Christian Long term ageing of alloy 2618A Results of the in vestigation of the "Long term ageing of alloy 2618A" were presented. 2018 ICAA 16 Montreal, Canada 17.06.2018 2018-06-26 OPUS4-44090 Zeitschriftenartikel Rockenhäuser, Christian; Schriever, Sina; von Hartrott, P.; Piesker, Benjamin; Skrotzki, Birgit Comparison of long-term radii evolution of the S-phase in aluminum alloy 2618A during ageing and creep A study was made on the effect of creep loading on the precipitate radii evolution of the aluminum alloy 2618A. The overageing process of the alloy was investigated under load at a temperature of 190 °C with stresses between 79 and 181 MPa and compared to stress free isothermal ageing. The precipitates responsible for strength were characterized using dark-field transmission electron microscopy (DFTEM). This allows the experimental Determination of radii distributions of the rod-shaped Al2CuMg precipitates and the evaluation regarding their mean precipitate radius. It was found that the mean precipitate radius enables the comparison of the different microstructural conditions of crept and uncrept samples. The mean precipitate radii of the samples experiencing creep are significantly higher than those of undeformed samples. It was shown that the acquired radii distributions are viable to determine averaged particle radii for comparison of the aged samples. A ripening process including pipe diffusion along dislocations describes the data on coarsening very well for the creep samples. Elsevier B. V. 2018 Materials Science & Engineering A 716 78 86 10.1016/j.msea.2018.01.033 2018-02-12 OPUS4-44706 Vortrag Rockenhäuser, Christian Lifetime Assessment of Aluminium radial compressor wheels considering material ageing The results of the project "Lifetime Assessment of Aluminium radial compressor wheels considering material ageing" were presented. 2018 FVV Frühjahrstagung 2018 Bad Neuenahr, Germany 22.03.2018 2018-04-18 OPUS4-44618 Forschungsbericht Rockenhäuser, Christian; von Hartrott, P.; Metzger, M.; Karlin, J.; Skrotzki, Birgit; Schweizer, C. Lebensdauerberechnung von Aluminium-Radialverdichterrädern unter Berücksichtigung der Werkstoffalterung Die Mikrostruktur von ausscheidungsgehärteten Aluminiumlegierungen ist von herausragender Bedeutung für ihre Festigkeit, da nur Werkstoffe mit gezielt eingestellter Mikrostruktur für Radialverdichterräder ausreichende Festigkeiten erreichen. Diese optimierte Mikrostruktur ändert sich jedoch während des Betriebs, denn die Bauteile werden bei Temperaturen eingesetzt, die nahe der Aushärtetemperatur liegen oder sogar darüber hinausgehen und folglich ist mit Alterung der Mikrostruktur und damit einhergehender Degradation der Eigenschaften zu rechnen. Diese Effekte konnten bisher in der Lebensdauervorhersage nicht berücksichtigt werden, da ihre diesbezüglichen Auswirkungen lediglich qualitativ bekannt waren. In diesem Forschungsvorhaben wurde daher für die Legierung EN AW-2618A einerseits eine sorgfältige und umfassende Charakterisierung der Gefügeentwicklung für anwendungsrelevante Temperaturen und Zeiten bis zu 25.000 h vorgenommen und andererseits eine solide Datenbasis bezüglich der mechanischen Eigenschaften (Zugfestigkeit, Kriechwiderstand, LCF-, TMF-Verhalten) und ihren Änderungen geschaffen. Darauf aufbauend wurde ein Verfahren entwickelt, um die Genauigkeit der Lebensdauerbewertung für Abgasturbolader (ATL)-Verdichterräder aus EN AW-2618A zu verbessern. Ein zeit- und temperaturabhängiges Verformungsmodell nach Chaboche, welches die wesentlichen Phänomene der Hochtemperaturverformung und der Wechselplastizität beschreibt, wurde erweitert und berücksichtigt nun die Werkstoffalterung, indem die Festigkeit nicht nur als Funktion der Temperatur, sondern auch des Alterungszustands (d. h. des mittleren Radius der Ausscheidungen) dargestellt wird. Für die Erweiterung des Modells zur Bewertung der Ermüdungslebensdauer unter Rainflow-klassierten Betriebslastkollektiven wurde analog verfahren. Die berechnete Lebensdauer der im Verlauf des Vorhabens durchgeführten LCF- und TMF-Versuche stimmt gut mit den experimentellen Ergebnissen überein. Forschungsvereinigung Verbrennungskraftmaschinnen e. V. (FVV) 2018 1 123 2018-04-04 OPUS4-45090 Zeitschriftenartikel Nützmann, Kathrin; Wollschläger, Nicole; Rockenhäuser, Christian; Kranzmann, Axel; Stephan-Scherb, Christiane Identification and 3D reconstruction of Cr5S6 precipitates along grain boundaries in Fe13Cr Metal sulfide grain boundary precipitates of a ferrous model alloy with 13 wt.% chromium formed at 650°C under a gas atmosphere containing 0.5% SO2 and 99.5% Ar were investigated after ageing for 3 h, 6 h, and 12 h. The precipitates formed along grain boundaries were identified as Cr5S6 using energy-dispersive x-ray spectroscopy in transmission electron microscopy and electron backscatter diffraction analysis. Serial focused ion beam slicing was conducted followed by three-dimensional reconstruction to determine the number, size, and penetration depth of the precipitates evolved at the different time steps. There was a linear increase in the number of precipitates with time, while their average size increased only for the initial aging time but became constant after 6 h. Based on these results, a model for grain boundary sulfidation of ferritic alloys is discussed. New York, NY Springer Science + Business Media The Minerals, Metals & Materials Society 2018 JOM 70 8 1478 1483 10.1007/s11837-018-2940-y 2018-06-04 OPUS4-46064 Zeitschriftenartikel von Hartrott, P.; Metzger, M.; Rockenhäuser, Christian; Skrotzki, Birgit Lebensdauerbewertung von alternden Werkstoffen Werkstoffe im Hochtemperatureinsatz verändern mit der Zeit ihre Mikrostruktur. Mit diesem Alterungsprozess einher geht eine Veränderung der mechanischen Eigenschaften ebenso wie eine Veränderung des Schädigungsverhaltens. Im Rahmen des FVV Vorhabens „Alterung und Lebensdauer" haben das Fraunhofer IWM in Freiburg und die BAM in Berlin die weit verbreitete warmfeste Aluminiumlegierung EN AW-2618A in verschiedenen Alterungszuständen experimentell charakterisiert und darauf aufbauend Modelle für die Lebensdauerbewertung mit der Finite-Elemente- Methode implementiert. Springer 2018 MTZ - Motortechnische Zeitschrift 79 10 72 76 10.1007/s35146-018-0085-8 2018-09-27 OPUS4-46065 Zeitschriftenartikel von Hartrott, P.; Metzger, M.; Rockenhäuser, Christian; Skrotzki, Birgit Lifetime assessment of aging materials Materials subjected to high-temperature service conditions will change their microstructure with time. Associated with this aging process is a change of mechanical properties as well as a change of damage mechanisms. Within the scope of the FVV project Aging and Lifetime, Fraunhofer IWM in Freiburg and BAM in Berlin (both Germany) experimentally characterized the widespread high-temperature aluminum alloy EN AW-2618A in different overaging states. Based on the experimental findings, models for numerical lifetime assessment with the finite-element method were implemented. Springer 2018 MTZ Worldwide 79 10 64 68 10.1007/s38313-018-0084-7 2018-09-27 OPUS4-46131 Posterpräsentation Rockenhäuser, Christian Influence of heat treatment and creep loading on an Al-Cu-Li alloy The influence of heat treatment and creep loading on the microstructure of an Al-Cu-Li alloy was investigated. Especially the formation of different precipitates (T1 and Theta') were characterized and the microstructural changes under different ageing conditions (with and without external strain) were investigated to determine the effect od stress on the ageing process. 2018 19th International Microscopy Congress (IMC19) Sydney, Australia 09.09.2018 14.09.2018 2018-10-02 OPUS4-46120 Vortrag Rockenhäuser, Christian The long-term ageing process of alloy 2618A The long-term ageing process of alloy 2618A was introduced and discussed The dark-field transmission electronmicroscopical resilts werde shown and evaluated regarding the precipitate radii. The influence of the precipitate radii regarding ageing was used for a preliminary ageing assessment. 2018 19th International Microscopy Congress (IMC19) Sydney, Australia 09.09.2018 14.09.2018 2018-10-02 OPUS4-46123 Posterpräsentation Rockenhäuser, Christian The long-term ageing process of alloy 2618A The long-term ageing process of alloy 2618A was introduced and discussed The dark-field transmission electronmicroscopical resilts werde shown and evaluated regarding the precipitate radii. The influence of the precipitate radii regarding ageing was used for a preliminary ageing assessment. 2018 19th International Microscopy Congress (IMC19) Sydney, Australia 09.09.2018 14.09.2018 2018-10-04 OPUS4-46129 Vortrag Rockenhäuser, Christian Influence of heat treatment and creep loading on an Al-Cu-Li alloy The influence of heat treatment and creep loading on the microstructure of an Al-Cu-Li alloy was investigated. Especially the formation of different precipitates (T1 and Theta') were characterized and the microstructural changes under different ageing conditions (with and without external strain) were investigated to determine the effect od stress on the ageing process. 2018 19th International Microscopy Congress (IMC19) Sydney, Australia 09.09.2018 14.09.2018 2018-10-02