  Strength, ductility, and failure properties of metals are tailored by plastic
deformation routes. Predicting these properties requires modeling of the
structural dynamics and stress evolution taking place on several length scales.
Progress has been hampered by a lack of representative 3D experimental data at
industrially relevant degrees of deformation. We present an X-ray imaging based
3D mapping of an aluminum polycrystal deformed to the ultimate tensile strength
(32% elongation). The extensive dataset reveals significant intra-grain stress
variations (36 MPa) up to at least half of the inter-grain variations (76 MPa),
which are dominated by grain orientation effects. Local intra-grain stress
concentrations are candidates for damage nucleation. Such data are important
for models of structure-property relations and damage.
