The Influence of Hydrogen on the Deformation Behavior of Zircaloy-4

The deformation behavior of Zr-based cladding forms a basis for fuel behavior codes and affects failure criteria; as such, it is critical to reactor safety. The present study examines the influence of hydrogen on the uniaxial deformation behavior of hydrided cold worked and stressrelieved Zircaloy-4 plate material. Specimens of various orientations (i.e., stress axis aligned with the rolling direction, the transverse direction, or normal-to-the plate surface direction) were tested in compression at a range of temperatures (25°, 300°, and 400°C), and strain rates (from 10/s to 10/s). Contrasting the deformation behavior of the material containing ~45 wt ppm H with that of the material containing ~420 wt. ppm H shows that increasing H content (a) causes a small decrease in the 0.2% yield stress that is eliminated at 1.0% flow stress, (b) increases the strain hardening in the rolling direction but not in the other orientations, (c) has no effect on the temperature dependence of the strain hardening, and (d) does not affect the strain-rate hardening behavior. Increasing H content also has no observable effect on the high degree of plastic anisotropy of this plate material which is manifested in difficult through-thickness deformation, resulting in high flow stresses for specimens oriented in the normal-to-plate-surface direction.