Mechanical surface treatments for improving fatique behavior in titanium alloys

• Autorzy: Ludian, T. , Wagner, L.
• Języki publikacji: EN

Abstrakty

EN

Mechanical surface treatments such as shot peening or ball-burnishing induce high dislocation densities and residual compressive stresses in near-surface regions. In addition, the surface roughness is changed. Micro-hardness and residual stress-depth profiles are evaluated in Ti-6Al-4V as a function of the Almes intensity being the main process parameter in shot peening. In the finite life regime, residual compressive stresses are shown to drastically increase the fatigue life by retarding crack growth from thesurface into the interior. However, in the HCF regime a shift in crack nucleation site occurs from the surface to subsurface regions where residual tensile stresses balance the outer compressive stress field. Therefore, the tensile mean stress sensitivity of the fatigue strength which can largely vary in Ti-6Al-4V needs to be taken into account in order to understand the observed differences in HCF responds to shot peening.

Słowa kluczowe

EN

shot peening; residual stresses; crack nucleation; micro-crack propagation

• Czasopismo: Advances in Materials Science
• Rocznik: 2008
• Tom: Vol. 8, nr 2(16)
• Strony: 44-52
• Opis fizyczny: Bibliogr. 8 poz., rys., tab.

Twórcy

autor

Ludian, T.

autor

Wagner, L.

• Clausthal University of Technology, Institute of Materials Science and Engineering, Agricolastr.6, 39768 Clausthal-Zellerfeld, Germany

Bibliografia

• 1. Schulze V.: Modern Mechanical Surface Treatments. Wiley-VCH, 2004.
• 2. Wagner L. and Luetjering G.: Influence of Shot Peening on the Fatigue Behavior of Ti-Alloys. Shot Peening, A. Niku-Lari [ed.], Pergamon Press, 1982, p. 453.
• 3. Gray H., Wagner L. and Lutjering G.: Influence of Shot Peening Induced Surface Roughness, Residual Macrostresses and Dislocation Density on the Elevated Temperature HCF-Properties of Ti-Alloys. Shot Peening, DGM, 1987. p. 447.
• 4. Peters M., Luetjering G. and Jaffee R.I.: Mechanical Properties of a Titanium Blading Alloy. EPRI-Report CS-2933, Electric Power Research Institute, Palo Alto, CA, USA, 1983.
• 5. Wagner L.: Mechanical Surface Treatments on Titanium Alloys: Fundamental Mechanisms. Gregory J. K, Rack H. J. and Eylon D. [eds.] TMS-AIME, 1996.
• 6. Kocan M., Rack H.J. and Wagner L.: Considering Environmental and Mean Stress Effects in Understanding the Fatigue Performance of Shot Peened Titanium Alloys. 11th World Conf. on Titanium, Kyoto, Japan, 2007. (in press)
• 7. Mueller J., Rack H. J. and L. Wagner.: Effects of Supra- and Subtransus Heat Treatments on HCF Performance of Ti-6Al-4V. 11th World Conf. on Titanium, Kyoto, Japan, 2007. (in press)
• 8. Mueller J., Rack H. J., Ludian T. and Wagner L.: Microstructural and Mean Stress Effects in Fatigue Performance of Shot Peened Ti-6Al-4V, 11th World Conf. on Titanium, Kyoto, Japan, 2007. (in press)