Low cycle fatigue behavior and deformation mechanisms of zirconium and zircaloy-4

The low cycle fatigue behaviors of zirconium and zircaloy-4 at room temperature, 400 degrees C and 600 degrees C have been investigated. The macroscopic stress response curves show that the cyclic deformation behavior of hexagonal zirconium and zircaloy-4 is characterized by three stages of cyclic hardening, saturation and cyclic softening. Hexagonal metals are sensitive to loading history, just like plane-slip materials. Cyclic plastic dissipated energy and fractional dimension methods are applied to lifetime prediction of zirconium and zircaloy-4. A power relationship is obtained between plastic dissipated energy, fractional dimension and fatigue lifetime. The deformation mechanism analysis shows that the possible deformation modes of zirconium and its alloys include prismatic, pyramidal and basal slipping, and twinning.