Accessible Requires Authentication Published by De Gruyter May 26, 2013

The Influence of Fatigue Loading on the Microstructure of an Austenitic Stainless Steel

Dariusz Skibicki and Stanislaw Dymski
From the journal Materials Testing

Abstract

The rotation of principal stress/strain axes, which takes place under conditions of non-proportional fatigue loading, may significantly worsen the fatigue life. An explanation of this phenomenon can be found through microstructure examination. In this paper, we present the results of a microstructure examination of a X5CrNi18-10 steel subjected to fatigue loading, both, proportional and non-proportional. The variability of the positions of the principal stress axes was controlled by a fatigue loading program that consisted of alternatively realised blocks of torsion and tension-compression. The microscopic investigations were carried out by X-ray structural analysis and the micro-hardness of the material was examined. The results revealed that the application of cyclic loading caused a plasticity-induced martensitic transformation. Comparative analysis showed that the transformation depended on intensity and the kind of applied loading.

Kurzfassung

Einfluss der Ermüdungsbelastung auf das Gefüge eines hochlegierten austenitischen Stahles. Die Rotation der Spannungs-/Dehnungs-Hauptachsen, wie sie unter nicht-proportionaler Ermüdungsbeanspruchung stattfindet, kann die Lebensdauer signifikant verringern. Erklärungen für dieses Phänomen können mittels Gefügeuntersuchungen gefunden werden. Im vorliegenden Beitrag werden die Ergebnisse der Gefügeuntersuchungen an dem hochlegierten austenitischen Stahl X5CrNi18-10 vorgestellt, der sowohl nichtproportionaler als auch proportionaler Beanspruchung unterzogen wurde. Die Veränderlichkeit der Positionen der Hauptachsen wurde mittels eines Ermüdungsbeanspruchungsprogrammes kontrolliert, das aus alternative realisierten Blöcken von Torsions- und Zug- Druck-Beanspruchungen bestand. Die Gefügeuntersuchungen wurden mittels Röntgenstrukturuntersuchungen durchgeführt und es wurde die Mikrohärte des Werkstoffes bestimmt. Die Ergebnisse zeigen, dass die aufgebrachten zyklische Beanspruchungen eine verformungsinduzierte martensitische Umwandlung verursachen. Vergleichsanalysen zeigten, dass diese Transformation von der Intensität und der Art der aufgebrachten Beanspruchung abhängt.


PhD, DSc. Dariusz Skibicki was born in 1967. He obtained his basic education in the area of mechanical engineering at University of Technology and Life Sciences in Bydgoszcz (Poland) in 1992. He started work on multiaxial fatigue of materials and in 2000 defended his Ph. D. After receiving the doctorate degree, his scope of interest has been enlarged by encompassing the fatigue of materials with problems of defining loading non-proportionality measures. In 2009 he received D.Sc. degree (Habilitation). Now he is associate professor at University of Technology and Life Science, where in the range of education he deals with CAD/CAE problems.

Professor Dr. habil. eng. Stanislaw Dymski represents sciences of engineering in discipline of the construction and operation of machinery. His research interests focus on metallography and heat treatment of cast iron. His degrees are: Ph.D. in 1983 at the Institute of Precision Mechanics, Warsaw and D.Sc., in 2002 at the Warsaw University of Technology. Now he is Professor Emeritus at the University of Technology and Life Sciences in Bydgoszcz.


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Published Online: 2013-05-26
Published in Print: 2010-11-01

© 2010, Carl Hanser Verlag, München