MATEC Web Conf.
Volume 165, 201812th International Fatigue Congress (FATIGUE 2018)
|Number of page(s)||7|
|Section||Very High Cycle Fatigue|
|Published online||25 May 2018|
Crack growth behaviour of aluminium wrought alloys in the Very High Cycle Fatigue regime
Institut für Werkstofftechnik, Universität Siegen, 57068 Siegen, Germany
2 Institut für Werkstoffwissenschaft, Technische Universität Dresden, 01069 Dresden, Germany
3 Institut für Werkstofftechnik, Universität Kassel, 34125 Kassel, Germany
* Corresponding author: firstname.lastname@example.org
Investigations have shown that in the regime of Very High Cycle Fatigue (VHCF) “natural” crack initiation often takes place underneath the material surface leading to crack propagation without contact to atmospheric components. In order to elucidate the environmental damage contribution and its effect on the VHCF long crack propagation, fatigue experiments with alternating environment (vacuum and laboratory air) were performed. An ultrasonic fatigue testing system (USFT) equipped with a small vacuum chamber was applied that enables the in-situ examination of the long fatigue crack propagation at a resonance frequency of about 20 kHz by using a long distance microscope. By means of the Focused-Ion-Beam technique, micro-notches were prepared in the USFT specimens. The tests were carried out on the aluminium alloys EN-AW 6082 and 5083 in different conditions. It has been found that the atmosphere has a significant influence on the VHCF long crack propagation which manifests itself in the crack path as well as in the crack growth rates. Because of pronounced single sliding in vacuum, shear-stress-controlled crack propagation was detected whereas in laboratory air normal-stress-controlled crack propagation occurred. Furthermore, it has been proven that the secondary precipitation state of the aluminium alloy significantly influences the VHCF long crack propagation in vacuum.
© The Authors, published by EDP Sciences, 2018
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (http://creativecommons.org/licenses/by/4.0/).
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