Influence of the production process on the deformation and fatigue performance of friction drilled internal threads in the aluminum alloy 6060*

Philipp Wittke; Yang Liu; Dirk Biermann; Frank Walther

doi:10.3139/120.110712

Published by De Gruyter March 27, 2015

Influence of the production process on the deformation and fatigue performance of friction drilled internal threads in the aluminum alloy 6060*

Einfluss des Fertigungsprozesses auf die Verformungs- und die Ermüdungseigenschaften fließgebohrter Innengewinde in der Aluminiumlegierung 6060

Philipp Wittke , Yang Liu , Dirk Biermann and Frank Walther

From the journal Materials Testing

https://doi.org/10.3139/120.110712

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Abstract

Aluminum alloys are used for enhancement of dynamic range, resource optimization and emission reduction in many fields of traffic engineering, whereby aluminum components are manufactured by means of welded, adhesive and screw joints. Friction drilling, as forming process with subsequent manufacturing of threads, offers the opportunity to produce an internal thread in lightweight profiles with a usable thread depth larger than the profile thickness, making use of local material expansion. Moreover, the direct manufacturing offers a huge potential for time and cost saving in comparison to conventional thread machining. Microstructural characterization of mechanical properties of EN AW-6060 internal threads, both in profile and bulk material specimens, was carried out using tensile tests and fatigue tests in the tensile loading range. A comparison was made between the manufacturing techniques tapping, thread forming and thread milling. The maximum tolerable loads of the profile specimens are about 50 % lower in the quasi-static range and about 25 % lower in the cyclic range in comparison to bulk material specimens. Formed threads show the best and cut threads the worst mechanical properties which were correlated with the production-related profile qualities and changes in microstructure. Multiple step tests prove that the fatigue limit of aluminum internal threads, validated in single step tests until 10⁷ cycles, can be reliably estimated by means of plastic strain.

Kurzfassung

Aluminiumlegierungen werden zur Dynamiksteigerung, Ressourcenschonung und Emissionsminderung in vielen Bereichen der Verkehrstechnik eingesetzt, wobei Aluminiumbauteile mit Hilfe von Schweiß-, Löt-, Klebe- oder Schraubverbindungen hergestellt werden. Das Fließbohren, als umformendes Verfahren in Kombination mit anschließender Gewindefertigung, bietet für Leichtbauprofile die Möglichkeit, durch lokales Aufweiten des Materials, ein Innengewinde mit größerer nutzbarer Gewindetiefe als die eigentliche Profilstärke zu erzeugen. Die direkte Einbringung der Gewinde bietet im Vergleich zur konventionellen Gewindebearbeitung zudem ein enormes Potential hinsichtlich Zeit- und Kostenersparnis. Die mechanischen Eigenschaften von Innengewinden in Profilproben und Vollmaterial aus der Aluminiumlegierung EN AW-6060 wurden in Zug- und Schwingversuchen im Zug-Schwellbereich mikrostrukturell charakterisiert. Verglichen wurden dabei die Fertigungsverfahren wie Gewindebohren, Gewindeformen und Gewindefräsen. Die maximal ertragbaren Belastungen der Profilproben sind im Gegensatz zum Vollmaterial im quasistatischen Bereich um ca. 50 % und im zyklischen Bereich um ca. 25 % geringer. Dabei weisen geformte Gewinde die besten und gebohrte Gewinde die schlechtesten mechanischen Eigenschaften auf, die mit den fertigungsbedingten Profilgüten und Gefügestrukturänderungen korreliert wurden. Mehrstufige Ermüdungsversuche belegen zudem, dass die in Einstufenversuchen bis 10⁷ Lastzyklen validierte Ermüdungsfestigkeit der Aluminium-Innengewinde, auf Basis der aus Spannung-Dehnung-Hysteresiskurven ermittelten plastischen Dehnungsamplitude, zuverlässig abgeschätzt werden kann.

§Correspondence Address, Philipp Wittke, Department of Materials Test Engineering (WPT), TU Dortmund University, Baroper Str. 303, D-44227 Dortmund, Web: www.wpt-info.de, E-mail: philipp.wittke@tu-dortmund.de

Dipl.-Ing. Philipp Wittke, born in 1982, studied Mechanical Engineering with specialization in Materials Science and Engineering at Ruhr-Universität Bochum (RUB), Germany. After his diploma thesis, he was a scientific assistant for two months (July/August 2011) at Werkstoffprüfung at RUB headed by Prof. Pohl. Since September 2011, he is working as a scientific assistant at Materials Test Engineering (WPT) in the Faculty of Mechanical Engineering at TU Dortmund University, Germany, headed by Prof. Walther. Since March 2014, he is also serving as group leader of metals at WPT, where he is working in the field of destructive materials testing.

Dipl.-Ing. Yang Liu, born in 1979, studied Mechanical Engineering with specialization in Production Engineering and received his diploma at TU Dortmund University, Germany, in 2011. Since April 2011, he is Scientific Assistant at the Institute of Machining Technology (ISF) in the Faculty of Mechanical Engineering at the same university, headed by Prof. Biermann. His research focuses on flow drilling process and threading.

Prof. Dr.-Ing. Dirk Biermann, born in 1963, studied Mechanical Engineering with the focus on Machine Technology at Dortmund University, Germany, from 1983 to 1989. He received his PhD in the research field of turning aluminum matrix composites in 1994. During his research work at the Institute of Machining Technology (ISF) from 1989 to 1999, he headed the Department Cutting Technology from 1993 to 1995 and became Chief Engineer in 1995. Afterwards, he worked as Head of Production at Dr. Schrick GmbH in Remscheid, Germany and was responsible for the production of internal combustion engines. Since April 2007, he is Professor of Mechanical Engineering and Head of the Institute of Machining Technology at TU Dortmund University. His research focuses on nearly all relevant machining processes such as turning, drilling, deep hole drilling, milling, grinding, honing and blasting as well as on the information technology environment of machining. Besides his work in research and teaching, he is engaged in various committees, e. g., as referee for the German Research Foundation (DFG), member of the Scientific Society for Production Engineering (WGP) and associate member of the International Academy for Production Engineering (CIRP). In addition, he is in close contact with production-oriented institutes, as well as with research institutions in the field of materials science worldwide. He has also participated in comprehensive interdisciplinary collaborations with the methodological sciences (computer science, mathematics and statistics). Since 2014, he is the Prorector of Research of TU Dortmund University.

Prof. Dr.-Ing. Frank Walther, born in 1970, studied Mechanical Engineering with a focus on Materials Science and Engineering at TU Kaiserslautern University, Germany, from 1992 to 1997. There he finished his PhD on the fatigue assessment of highly-loaded railway ICE wheel steels at Institute of Materials Science and Engineering (WKK) in 2002. From 2002 to 2008, he headed the research group “Fatigue Behavior” at WKK and finished his postdoctoral qualification (habilitation) in Materials Science and Engineering in 2007. Afterwards, he joined Schaeffler AG in Herzogenaurach, Germany, and took responsibility for Public Private Partnership comprising public research funding and materials research projects within Corporate Development. Since 2010, he has been Professor for Materials Test Engineering (WPT) at TU Dortmund University, Germany. His research portfolio includes determination of structure property relationships of metal- and polymer-based construction materials and components taking the influence of manufacturing and joining processes as well as service loading and corrosion deterioration into account. New measurement and destructive/non-destructive testing techniques are applied for the characterization of fatigue behavior from LCF to VHCF range under mechanical, thermal, chemical and mixed influences, as well as new physically based approaches for the calculation of damage development and (remaining) fatigue life. Besides, he is engaged in various committees, e. g., as referee for German Research Foundation (DFG), member of board of German Materials Society (DGM), member of German Association for Materials Research and Testing (DVM), member of Association of German Engineers (VDI) and member of Scientific Association of Materials Engineering (WAW). Prof. Walther published more than 120 reviewed papers and conference proceedings and maintains close scientific contact with institutions and industries in materials science and engineering field worldwide.

Extended version of the presentation at the conference Werkstoffprüfung 2013, Neu-Ulm, Germany

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Published Online: 2015-03-27

Published in Print: 2015-04-01

Influence of the production process on the deformation and fatigue performance of friction drilled internal threads in the aluminum alloy 6060*

Abstract

Kurzfassung

References

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