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On the Fatigue Behaviour of Wrought Magnesium Alloys*

Über das Ermüdungsverhalten der Magnesiumknetlegierungen
  • Lenka Fuskova , Jan Bohlen , Sangbong Yi and Dietmar Letzig
From the journal Materials Testing

Abstract

The influence of crystallographic texture on the mechanical properties of magnesium alloys is already well-known. However, it is not clear how the crystallographic texture affects the fatigue properties in the sense of cyclic deformation behaviour of magnesium alloys. The objective of this study is to investigate and compare the deformation processes of the extruded magnesium alloys AZ31 and AZ80 during static and cyclic tensile testing. The influence of the loading condition and chemical composition on the evolution of the microstructure and the crystallographic texture has been observed. Changes of the plastic strain have been observed and have been interpreted for both AZ alloys with cyclic hardening curves. However, the maximal stress during the fatigue test was higher than the TYS for both alloys. Both experimental materials exhibited significant lower plastic deformations and lower density of tensile twins compared to static tensile test. The microstructure and texture analyses have been performed before and after experiments.

Kurzfassung

Der Einfluss der kristallographischen Textur auf die mechanischen Eigenschaften von Magnesiumlegierungen ist bereits bekannt. Allerdings ist es noch nicht klar, wie die kristallographische Textur die Ermüdungseigenschaften der Magnesiumlegierungen hinsichtlich das zyklischen Verformungsverhalten beeinflusst. Das Ziel dieser Studie ist die Deformationsprozesse von stranggepressten Magnesiumlegierungen AZ31 und AZ80 während des statischen und zyklischen Zugversuchs zu untersuchen und zu vergleichen. Der Einfluss der Belastungsbedingungen und der chemischen Zusammensetzung auf die Gefüge und auf die kristallographische Texturentwicklung wurde beachtet. Für beide geprüften Legierungen wurden die Änderungen in der plastischen Dehnung beobachtet und mit den zyklischen Verfestigungskurven interpretiert. Die Werte der maximalen Spannung in zyklischen Belastungen wurden für beide Legierungen höher als die Dehngrenze. Jedoch weisen beide experimentellen Materialien erheblich niedrigere plastische Verformungen und niedrigere Dichte der Zugzwillinge im Vergleich zu dem statischen Zugversuch auf. Die mikrostrukturellen und kristallographischen Analysen vor und nach den Versuchen wurden ausgeführt.


*

This Contribution has already been published in the Proceedings of the International Conference on Low Cycle Fatigue (LCF 6).

Dr.-Ing. Lenka Fuskova, born 1974, studied Material science at the Faculty of Mechanical Engineering of the University Zilina (Slovak Republic) and obtained her PhD degree in 2004 on cyclic plasticity of metals by investigating the mean stresses and higher frequencies. Since 2006, she has been working at the GKSS Research Centre in Geesthacht (Germany) in the field of wrought magnesium alloys (Magnesium Innovation Centre – MagIC).

Dr.-rer. nat. Jan Bohlen, born 1970, studied Metal and Material Physics at the Georg August University in Göttingen, Germany, and obtained his doctoral degree in 2000 on structural characterisation of polymer materials. Since 2001, he has been working with the GKSS Research Centre in Geesthacht in the field of wrought magnesium alloys.

Dr. Sangbong Yi, born 1972, studied Material Science and Engineering at the Kumoh National University of Technology in Kumi, Korea and obtained his PhD degree in 2005 on deformation mechanisms of Magnesium alloys at the Technical University Clausthal (Germany). Since 2008, he has been working at the GKSS Research Centre in Geesthacht (Germany) in the field of wrought magnesium alloys.

Dr.-rer. nat. Dietmar Letzig, born 1961, studied Physics at the University of Hamburg. In 1989, he started to work as a scientist at the Department of Physical Metallurgy of the Max-Planck Institute for Iron Research and obtained his doctoral degree in 1994 at the Technical University RWTH Aachen. After that he worked as a research metallurgist in the Research Centre Alcan International Banbury, UK, in the field of automotive Al-alloys. Since 2000, he has been working as head of the Department Wrought Magnesium Alloys and Characterisation at the GKSS Research Centre in Geesthacht.


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Published Online: 2013-05-28
Published in Print: 2009-09-01

© 2009, Carl Hanser Verlag, München

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