  Ductile fracture has been extensively studied in metals with weak mechanical
anisotropy such as copper and aluminum. The fracture of more anisotropic
metals, especially those with a hexagonal crystal structure (e.g. titanium),
remains far less understood. This paper investigates the ductile fracture
process in commercially pure titanium (CP-Ti) with particular emphasis on the
influence of grain orientation and local state of strain on void growth. An
experimental approach was developed to directly relate the growth of a void in
three dimensions to its underlying grain orientation. Grain orientation was
obtained by electron back scattered diffraction on void-containing CP-Ti sheets
prior to their diffusion bonding. Changes in void dimensions were measured
during in-situ straining within an x-ray tomography system. The strong
influence of the embedded grain orientation and that of its neighbors on void
growth rate and coalescence has been experimentally quantified. Finite element
crystal plasticity simulations that take into account both grain orientation
and the local strain state were found to predict the experimental void growth.
Grains where basal slip dominates show the largest void growth rates because
they are closer to a plane strain condition that favors void growth and
coalescence.
