Recovery and deformation substructures of Zry-4 in high temperature plasticity at stationary stress

M BOCEK; I ALVAREZ

JOURNAL OF NUCLEAR MATERIALS

Elsevier

Año: 1982 vol. 105 p. 293 - 301

0022-3115

. It was the aim of the present investigation to examine how the recovery rate in creep is influenced by a non-stationary stress. For purposes of phenomenological analysis it is postulated that, irrespective of whether the applied stress is stationary or not, for large strains the mean internal stress ói approaches a stationary value ói,s. The stationary recovery rate Rs for constant load creep turns out be governed by the applied stress indicating that the recovery mechanism is dynamic in nature. For ó-ramp loading, Rs is dependent on the stress rate ó. In tensional stress cycling, Rs is governed by the maximum stress óM and is also dependent on the ratio of óM to the minimum stress ó0.TEM examination of Zircaloy-4 specimens crept at 800°C at constant and cycling load respectively could not reveal any differences in the deformation substructure for the two loading types. Subgrain formation did not appear, individual dislocations were observed only rarely. However, typical networks were formed as well as pileups which perhaps are responsible for the back stress in high temperature plasticity (HTP).