SEDL / STP / STP1023-EB / STP18889S

Stress Versus Strain Rate Characteristics of Zircaloy Cladding Tubes Subjected to Various Deformation Paths

Suzuki, H
Research assistant and professor, Sophia University, Tokyo,

Okubo, T
Research assistant and professor, Sophia University, Tokyo,

Pages: 22    Published: Jan 1989

Download this paper for $25 PDF (344K)          View License Agreement
Abstract

Load relaxation properties of unirradiated Zircaloy nuclear fuel claddings were measured at 648 K. Deformation paths preceding the relaxation were altered in order to study the factors affecting relaxation properties. The histories chosen were (1) constant strain rate tensile deformation, (2) constant load creep deformation, and (3) biaxial followed by uniaxial creep. Stress versus time records were obtained from the relaxation runs. Stress versus strain rate curves were further derived and effects of prior strain rate, strain, transient deformation and strain hardening on relaxation properties were discussed. It was found from the experimental results that after strain hardening and transient deformation saturates, the strain rate just prior to relaxation has a major effect on the stress versus strain rate characteristics. This finding holds both for the relaxation after tension and creep. Existing models could not describe these findings.