A review of texture and texture formation in Zircaloy tubing. Discussion

In hexagonal close-packed metals, the development of a strong deformation texture is caused by the reduced availability of slip systems, their nonsymmetrical distribution, and the fact that twinning obeys strict, crystallographic orientation relationships. This in turn occurs characteristically according to the metal-specific structure parameters. In zirconium and Zircaloy, the development of the strong deformation texture is caused by the complicated interaction between slip and twinning. The factor governing the texture formation is the material flow, which for tube reductions is determined not only by the reduction in cross-section, but in addition by the reductions in wall thickness and diameter, and more specifically by the relative ratio of wall to diameter reduction. The knowledge gained from the tube reduction process can be used to explain the texture formation during sheet rolling and wire drawing. By knowing the relationship between texture formation and reduction parameters, it is possible to tailor the texture in Zircaloy tubing within the given limits, according to in-service requirements.