Effect of the annealing temperature on the creep strength of cold-worked Zircaloy-4 cladding

Transverse creep strength of Zircaloy-4 tubing annealed in the range of 440 to 650°C has been evaluated by internal pressure tests, short-time control tests at 400°C, and long-time tests, as well as out-pile or in-pile, between 330 to 400°C. For low and intermediate stresses (lower than 133 MPa), it is observed that transverse creep strength increases while the annealing temperature is increased from 440 to 650°C. In-pile tests do confirm this trend. The effect of the annealing temperature on the yield and creep anisotropy of the tubes has been evaluated at 400°C. From these results, it is concluded that the beneficial effect of a recrystallization treatment on the creep strength of Zircaloy-4 tubes is related to an effect of texture variation.