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 (gl iding and/or twinning) which are different according to the type of al loys and may vary with deformation degree. We have modelled texture ev olution during cold rolling of two Ti and Zr alloys, using a Taylor th eory. The choice or relevance of the model variant (FC = Full Constrai ned, RC = Relax Constrained) are discussed. In order to account for th e 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 Figur es (PF) and for the Orientation Density Function (ODF), agree well wit h experiment in the range from 0 to 80% reduction. Therefore, a good k nowledge of the microstructure evolution and of the deformation mechan isms is required.