Title: Cycle induced microstructural changes

Authors: Jaroslav Fiala; Pavel Mazal; Michal Kolega

Addresses: New Technologies Research Centre of the University of West Bohemia Plze?, Universitní 8, 30614 Plze?, Czech Republic. ' Faculty of Mechanical Engineering, Brno University of Technology, Technicka 2, 616 69 Brno, Czech Republic. ' New Technologies Research Centre of the University of West Bohemia Plze?, Universitní 8, 30614 Plze?, Czech Republic

Abstract: The aim of this research was to look for systematic structural changes in a metal subjected to repetitive or fluctuating stress which may be used for monitoring structural degradation and estimating residual life of fatigued components. A special X-ray technique was used to this end, which consists in the examination of the number and size of individual diffraction spots. As each diffraction spot represents the diffraction image of a coherent scattering region, such an examination provides information on the architecture of dislocation network forming the interface between the coherent X-ray diffraction scattering regions. Analysis of the structure of an aluminium alloy EN-AW-6082 subjected to cyclic stress proved that the effect of cycling was first to transform an irregular dislocation distribution into cellular one. The cells of the dislocation network formed in this way coagulated and grew in size under repeated stress up to a certain number of cycles when the effect of cycling reversed and the cells gradually disintegrated.

Keywords: fatigue; aluminium alloys; microstructure; X-ray diffraction; cyclic stress; dislocation network; structural degradation; coherent scattering region; cellular distribution; dislocations; residual life.

DOI: 10.1504/IJMMP.2011.043221

International Journal of Microstructure and Materials Properties, 2011 Vol.6 No.3/4, pp.259 - 272

Available online: 20 Oct 2011 *

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