Stacking fault energy and microstructure effects on torsion texture evolution

A series of experiments and simulations that vary the texture and microstructure simultaneously are used to establish the role of the microstructure in texture formation in FCC metals. The stacking fault energy (SFE) of the metal, which is known to have a strong impact on texture and microstructure, is the vital parameter used to make these variations. It was determined that the wide variety of textures and microstructures observed as a function of SFE and temperature was developed by slip processes alone; twinning was not necessary, as previously thought. The different textures are caused by (i) variations in local slip patterns within a single grain, as revealed by grain subdivision into differently deforming cell blocks; and (ii) more subtly by the cell-block shape. The local selection of slip systems creating the lattice rotations within a cell block is altered by the planarity of slip. Slip planarity is controlled by the SFE and temperature. It is hypothesized that the new texture components, that are distinct from the generally accepted ideal components, are created by the different slip processes occurring as a result of low SFE and low temperature. A more subtle effect of grain subdivision is related to the cell-block shapes that develop as a function of SFE and temperature and correspond to the different textures observed. The shape of the cell block is related to the level of constraint required by the deformation. The slip pattern changes and cell-block shapes correlate with the presence or absence of certain ideal texture components whose evolution is not simulated. Materials and conditions with similar deformation microstructures developed similar textures in the experiments.