Effects of 3D Microstructure on Short Fatigue Crack Growth Behavior in Ti-6Al-4V

Abstract

A load-controlled fatigue test was performed at R = 0.1 in low cycle region in a dual phase Ti-6Al-4V alloy. In situ computed tomography was employed to measure short crack growth rates in the α, β phase and interphase for two crack length regions. Afterwards, a post-mortem serial sectioning coupled with electron backscattering diffraction (EBSD) was conducted to identify the crystallographic orientations of the α phase. Crack mainly propagates through the α phase in a facet-like growth in the first region. As crack follows the basal planes with high basal Schmid factors its growth rate increases, however, this rate decreases by following the prismatic planes with low factors. In the second region, crack follows mainly the prismatic planes with high prismatic Schmid factors in a tortuous-like growth.