Improvement of yield locus calculation, i.e. better fit with experimental results, was
achieved for Zircaloy tubes with deformation and recrystallization textures in
the following way: (1) Replacement of information from {101¯0}- and (0001)-pole
figures by identification of preferred orientation parallel to the tube axis in
combination with the basal pole density distribution in the plane between radial and
tangential direction as a function of the tilt angle γi. (2) Calculation of those parts of
the yield locus which are independent of mechanical twinning. For uniaxial tensile
stress parallel to the tube axis the slope m of the yield locus line for prismatic glide is
given by mi=cos2γi. (3) Calculation of yield locus parts depending on mechanical
twinning using experimentally well established ratios of critical resolved shear
stresses for prismatic slip and several twinning systems.Mechanical twinning on {112¯2}-planes was confirmed by texture analysis of
plastically deformed tubes after yield locus investigation.