Research Progress of Titanium Alloys and Their Diffusion Bonding Fatigue Characteristics

This paper concentrates on the research progress of titanium alloys and their diffusion bonding fatigue characteristics, and summarizes the laws of fatigue crack initiation and growth of titanium alloys with/without welding. The chemical composition, classification, and common welding method of titanium alloys are stated, with emphasis on the features and advantages of diffusion bonding. The phenomena of slip band formation and dislocation movement under cyclic loading are described, and the mechanism of fatigue crack initiation is clarified. The selection of microstructures is a common method to optimize mechanical properties of titanium alloys. Previous studies suggested that the laminated structure is an important mode to realize the low fatigue crack growth rate of titanium alloys. Improper parameters of the welding process can cause joint defects, and further heat treatment can reduce joint defects while improving the fatigue life and strength. Finally, the multilayer and heterogeneous laminates of titanium alloys produced by diffusion bonding are briefly described to realize the possibility of high damage tolerance.