Recovery behavior of cold-worked and quenched Zircaloy with varying oxygen content

Abstract

The recovery behavior of cold-worked and quenched Zircaloy-2 was examined in terms of variations in oxygen content, from about 140 ppm to 1700 ppm O. The cold work was produced by swaging to a 50% reduction in area at room temperature and the quenching was done into ice-brine from a temperature of 800° C. Isochronal recovery started at lower temperatures for the lowest oxygen alloys, but the rates of recovery were greater for the high-oxygen alloys. In addition, the high-oxygen alloys appeared to undergo hardening during the isochronal annealing, reaching a peak in the temperature region of 475–525°C. Net strengthening achieved by quenching was greater than the 50% cold work. This was attributed to the dual effect of solute supersaturation and formation of quenched-in defect clusters. Hardness change, however, occurred in three distinct stages. The change in oxygen content appeared to have a less significant effect on the recovery of quenched-in damage than on the recovery of cold-work damage.