Fatigue behaviour in titanium-based alloys

Abstract

Fatigue failures in Ti-alloys have been attributed by applications in gas turbine, biomedical and industrial sectors. The major variables are temperature, corrosion and loading regimes. Interior crack formations appear to be more difficult as compared to surface originating cracks. Type of alloy system, specification for operating status and heat treatment has affected fatigue properties in different manner. Sometimes precipitation produces favourable consequences, where as in some cases it disfavours development of fatigue properties. Ti-alloys consist transition parameters for application above which alloys undergo enhanced degradation under fatigue. The central theme of the paper is to study fatigue crack initiation and its propagation for various modes of fatigue processes. Simulation of different mechanical properties in titanium base alloys is described in the review to study the relative competencies with service exposure. Location and magnitude of plastic shear bands in α-phase grains, phase morphology and orientation and microscale plastic strain distribution of ratcheting under high cycle fatigue are some important parameters. Superior performance is achieved from coarse-grained alloy containing microstructurally small cracks under mixed mode loading. Foreign object damage induces microstructurally small defects, where as stress relief annealing improves fatigue limit. Comparative performance and scar formation under fretting fatigue evaluate best performance from coated components.