Numerical simulations of cylindrical void growth in Mg single crystals

In this work, growth of cylindrical voids corresponding to different stress states in Mg single crystal under plane strain conditions is analyzed using a crystal plasticity based finite element procedure which accounts for twinning through a quasi-slip approximation. Two lattice orientations are considered with the c-axis along the thickness in one orientation and major principal stress direction in the other. Profuse tensile twinning occurs in the second orientation. To understand its influence clearly, this orientation is also analyzed with tensile twinning intentionally suppressed. The results show a pronounced effect of texture hardening triggered by tensile twinning in slowing down void growth. However, once lattice reorientation occurs, multiple slip systems become active causing more rapid void growth. The simulations also predict a transition in void coalescence mechanism from internal ligament necking to shear localization along an inclined band with reduction in biaxiality stress ratio when tensile twinning occurs.