Observation and quantification of three-dimensional crack propagation in poly-granular graphite

► X-ray tomography was used to obtain a 3D image of the specimen made of polygranular graphite before and after fracture. ► Digital volume correlation was used to obtain the full-field displacement by following the features in tomographic image. ► The full-field displacements were used to visualise the crack and to measure the 3D crack opening displacement. ► No clear cut between the macromechanical crack and the uncracked material was observed. ► A fracture process zone, containing microcracks, forms the transition between the cracked and uncracked region.