High Temperature Fatigue of Mechanically Surface Treated Materials

Author:  Altenberger, Noster, Scholtes, Ritchie
Source:  Conf Proc: ICSP-8 Sept. 16-20, 2002 Garmisch-Partenkirchen, Germany pps. 48
Doc ID:  2002063
Year of Publication:  2002
Authors Igor Altenberger 1, Ulf Noster 2, Berthold Scholtes 2, Robert O. Ritchie 1 1 Department of Materials Science & Engineering, University of California, Berkeley, CA, USA 2 Institute of Materials Technology, University Kassel, Kassel, Germany Introduction The most well known effect of mechanical surface treatments on metallic materials is the improvement in fatigue properties. It is therefore not surprising that most of the archival literature on mechanical surface treatments, such as shot peening, deep rolling and laser shock peening, deals with the effect of near-surface properties on fatigue behavior. Most of these studies, however, are confined to room temperature fatigue behavior; in comparision, the effect of mechanical surface treatment on fatigue behavior at high temperatures has been rarely investigated [1-5]. The reason for this disparity can be found in the popular belief that fatigue strength improvement by mechanical surface treatments is mainly due to the presence of compressive residual stresses, and since such stresses should anneal out at elevated temperatures, mechanical surface treatments for high temperature applications would appear questionable. However, this view may be over simplistic as there is always a possibility that the residual stresses may be at least partially stable at elevated temperatures [6]; in addition, other factors may be involved, such as the nature of the near-surface microstructure. Accordingly, it is the objective of this study to examine the role of mechanical surface treatments on the high temperature fatigue behavior of several metallic engineering materials. Moreover, it is the aim of this work to clarify what are the critical temperature "thresholds' at which near-surface microstructures and residual stresses become unstable and whether this can explain the observed fatigue behavior.

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