Hydrogen-assisted fatigue crack growth in beta-annealed Ti-6Al-4V

In the present study, the effect of internal hydrogen on beta-annealed Ti-6Al-4V subjected to a very small amplitude fatigue loading (a cyclic amplitude equal to 5% of the maximum load or a stress ratio, R, of 0.90) was determined. The fatigue crack growth rates and fatigue crack growth threshold stress intensities were determined and compared for beta-annealed Ti-6Al-4V with hydrogen contents of 40 ppm, 370 ppm, and 1000 ppm. The observed secondary cracking and unique fatigue crack growth kinetics in 1000 ppm hydrogen-charged Ti-6Al-4V are discussed in relation to stress-assisted hydride information in the crack tip region