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a b s t r a c tVoid growth and coalescence in single crystals are investigated using crystal plasticity based 3D finite element calculations. A unit cell involving a single spherical void and fully periodic boundary conditions is deformed under constant macroscopic stress triaxiality. Simulations are performed for different values of the stress triaxiality, for different crystal orientations, and for low and high work-hardening capacity. Under low stress triaxiality, the void shape evolution, void growth, and strain at the onset of coalescence are strongly dependent on the crystal orientation, while under high stress triaxiality, only the void growth rate is affected by the crystal orientation. These effects lead to significant variations in the ductility defined as the strain at the onset of coalescence. An attempt is made to predict the onset of coalescence using two different versions of the Thomason void coalescence criterion, initially developed in the framework of isotropic perfect plasticity. The first version is based on a mean effective yield stress of the matrix and involves a fitting parameter to properly take into account material strain hardening. The second version of the Thomason criterion is based on a local value of the effective yield stress in the ligament between the voids, with no fitting parameter. The first version is accurate to within 20% relative error for most cases, and often more accurate. The second version provides the same level of accuracy except for one crystal orientation. Such a predictive coalescence criterion constitutes an important ingredient towards the development of a full constitutive model for porous single crystals.

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Rolling textures of low-carbon steel predicted by full constraints and relaxed constraints Taylor models, as well by a self-consistent model, are quantitatively compared to experimental results. It appears that none of these models really performs well, the best results being obtained by the Pancake model. A new model ("Lamel model") is then proposed as a further development of the Pancake model. It treats a stack of two lamella-shaped grains at a time. The new model is described in detail, after which the results obtained for rolling of low-carbon steel are discussed. The prediction of the overall texture now is quantitatively correct. However, the "),-fibre components are better predicted than the a-fibre ones. Finally it is concluded that further work is necessary, as the same kind of success is not guaranteed for other cases, such as rolling of f.c.c, materials.

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