  This study addresses ductile fracture of single grains in metals by modeling
of the formation and propagation of transgranular cracks. A proposed model
integrates gradient extended hardening, phase-field modeling for fracture, and
crystal plasticity. It is presented in a thermodynamical framework in large
deformation kinematics and accounts for damage irreversibility. A micromorphic
approach for variationally and thermodynamically consistent damage
irreversibility is adopted. The main objective of this work is to analyze the
capability of the proposed model to predict transgranular crack propagation.
Further, the micromorphic approach for damage irreversibility is evaluated in
the context of the presented ductile phase-field model. This is done by
analyzing the impact of gradient-enhanced hardening considering micro-free and
micro-hard boundary conditions, studying the effect of the micromorphic
regularization parameter, evaluating the performance of the model in ratcheting
loading and and testing its capability to predict three-dimensional crack
propagation. In order to solve the fully coupled global and local equation
systems, a staggered solution scheme that extends to the local level is
presented.
