Effect of Shot Peening on Fatigue Performance of Gamma Titanium Aluminides

Author:  Lindemann, Roth-Fagaraseanu and Wagner
Source:  Conf Proc: ICSP-8 Sept. 16-20, 2002 Garmisch-Partenkirchen, Germany
Doc ID:  2002051
Year of Publication:  2002
Abstract:  
Authors Janny Lindemann 1), Dan Roth-Fagaraseanu 2) and Lothar Wagner 1) 1) Chair of Physical Metallurgy and Materials Technology, Technical University of Brandenburg at Cottbus, Cottbus, Germany 2) Rolls-Royce Deutschland, Dahlewitz, Germany Introduction Gamma titanium aluminides are attractive candidates for application as blade material in the high-pressure part of the compressor of gas turbines. Compared to the yield stress values at both room temperature and the typical service temperature of 650 C, the 10 7 cycles fatigue strengths at these temperatures are extraordinarily high, particularly if related to the material's density being only half that of the commonly used Ni-superalloys [1,2]. To further improve the fatigue performance of y(TiA1), mechanical surface treatments such as shot peening or roller-burnishing can be utilized. These treatments induce high dislocation densities owing to plastic deformation in near-surface regions, change the surface topography and generate residual compressive stresses. While the effect of process parameters of mechanical surface treatments on fatigue in structural steels, aluminum and conventional titanium alloys was often studied, no such information is available for gamma titanium aluminides. The present work is part of a project which was undertaken to determine potential improvements in room and elevated temperature applications of y(TiA1) by shot peening.