Surface Effects on the Mechanical Properties of Gamma Titanium Aluminides

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Surface conditions are of significant importance for the fatigue performance of rotating components for aircraft and automotive applications. Compared to the electropolished reference state the fatigue performance of gamma titanium aluminides at ambient temperature can be significantly improved by shot peening, while the fatigue strength after roller burnishing is hardly affected. Fatigue strength improvements after shot peening are mainly caused by cyclically stable residual compressive stresses in the near-surface region. Notably, also conventional turning operations generate high dislocation densities and residual compressive stresses in the near-surface region resulting in fatigue strength improvements similar to shot peening. Surface strengthening by shot peening or machining leads to subsurface fatigue crack nucleation and overcompensates the detrimental influence of the high surface roughness on fatigue. However, for temperatures above 650 °C, residual compressive stresses induced by shot peening and machining quickly relax. This indicates that, at elevated temperatures, surface roughness and dislocation strengthening become increasingly important for the fatigue performance of components.

Info:

Periodical:

Materials Science Forum (Volumes 706-709)

Main Theme:

Edited by:

T. Chandra, M. Ionescu and D. Mantovani

Pages:

1071-1076

DOI:

10.4028/www.scientific.net/MSF.706-709.1071

Citation:

J. Lindemann et al., "Surface Effects on the Mechanical Properties of Gamma Titanium Aluminides", Materials Science Forum, Vols. 706-709, pp. 1071-1076, 2012

Online since:

January 2012

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$38.00

[1] M. Glavatskikh: Verbesserung des Ermüdungsverhaltens von g-TiAl-Legierungen durch mechanische Oberflächenbehandlung (PhD thesis, Technical University Cottbus, 2011).

[2] J. Lindemann, M. Glavatskikh, C. Leyens, M. Oehring, F. Appel, in: Ti-2007 Science and Technology, edited by M. Niinomi et al, Vol. II, The Japan Institute of Metals (2007).

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