3D characterisation of short fatigue crack in Ti 6246

In the present study, fatigue crack propagation was imaged non-destructively in 3 dimensions during in-situ fatigue loading of Ti-6246 using X-ray microtomography on beam-line ID19 at the European Synchrotron Radiation Facility (ESRF). Phase contrast enabled the visualization of the two-phase microstructure and in combination with absorption contrast the crack growth was recorded in-situ during fatigue test. In order to obtain the crystallographic orientation of individual grains along the crack path a 3D EBSD volume was recorded subsequently. By combining both techniques it was possible to relate the crystallographic orientation of grains to crack arrest and accelerated crack propagation. It is shown that the lamellar grain orientation and morphology have a great influence on the crack diversion and deviation. Moreover, crack resistance of the alloy is investigated by means of EBSD grain characterisation methodology, orientation and misorientation data evaluations.