Effect of Surface Integrity on Hot Fatigue Life of TiAlNb Intermetallic Alloy.

The effect of surface integrity on the hot fatigue performance of TiAlNb alloy was investigated. A turning process was used to prepare the standard specimens for hot fatigue tests. The surface integrity characterization and axial fatigue tests were performed. The results show that the influence of surface roughness on the hot fatigue performance of the TiAlNb alloy is a secondary factor. The compressive residual stress and enhanced microhardness in the surface layer has a significant effect on the hot fatigue life and they are dominant in the hot fatigue behavior of the TiAlNb alloy. Through the investigation on the characteristics of the fatigue fractures, the fatigue propagation process was significantly suppressed because of the strong residual compressive stress and microhardness distribution on the surface layer of the TiAlNb specimen.