MODELING OF TEXTURE EVOLUTION FOR MATERIALS OF HEXAGONAL SYMMETRY .2. APPLICATION TO ZIRCONIUM AND TITANIUM ALPHA-ALLOYS OR NEAR-ALPHA-ALLOYS

This work describes the evolution of texture and microstructure during cold rolling of different Ti and Zr alloys. These alloys accommodate deformation with prismatic glide and with ''secondary'' mechanisms (gliding and/or twinning) which are different according to the type of alloys and may vary with deformation degree. We have modelled texture evolution during cold rolling of two Ti and Zr alloys, using a Taylor theory. The choice or relevance of the model variant (FC = Full Constrained, RC = Relax Constrained) are discussed. In order to account for the changes in the secondary systems during deformation, we have decided to work by steps, since there are no defined hardening laws accepted for each system. The results of the modelling, both for the Pole Figures (PF) and for the Orientation Density Function (ODF), agree well with experiment in the range from 0 to 80% reduction. Therefore, a good knowledge of the microstructure evolution and of the deformation mechanisms is required.