Direct observation of three-dimensional short fatigue crack closure behavior in Ti-6Al-4V alloy using ultra-high-resolution X-ray microtomography

Local 3D short fatigue crack closure behavior was investigated in Ti-6Al-4V alloy using ultra-high-resolution X-ray microtomography (XMT). The results show that the inhomogeneous distribution of plasticity-induced and roughness-induced crack closure is caused by the variation of crack path morphologies. These crack path mor-phologies exhibited heterogeneous plastic deformation at the crack-tips due to the anisotropic nature of alpha grains and varying extents of crack tilting and twisting caused by the interaction of the crack front with alpha/alpha boundary or alpha/alpha + beta interface. It was revealed via surrogate-based statistical analysis that the Schmid factor has the strongest effect on crack growth rate.

Automated summary

Local 3D short fatigue crack closure behavior in Ti-6Al-4V alloy was investigated using ultra-high-resolution X-ray microtomography (XMT). The study revealed that the inhomogeneous distribution of plasticity-induced and roughness-induced crack closure is caused by the variation in crack path morphologies. These crack path morphologies exhibit heterogeneous plastic deformation at the crack tips due to the anisotropic nature of alpha grains and varying extents of crack tilting and twisting caused by the interaction of the crack front with alpha/alpha boundary or alpha/alpha + beta interface. Surrogate-based statistical analysis showed that the Schmid factor has the strongest effect on crack growth rate.