Fatigue crack growth rates in alpha titanium: Faceted vs. striation growth

Cyclic and dwell fatigue crack growth (FCG) rates were measured in single-phase Ti–7Al (wt.%) directly from fractured samples. A quantitative method using stereo pairs was used to eliminate the uncertainty associated with these measurements on two-dimensional projections of the three-dimensional fracture features. The results show that FCG rates increased by up to two orders of magnitude under dwell fatigue loading conditions when propagating by the faceted mechanism compared to the classical striation growth mechanism.