Temperature dependence of elongation in Zircaloy-4 nuclear fuel claddings

摘要

Temperature and strain rate dependence ofelongation and flow stress in Zircaloy-4 CANDU nuclear fuelcladdings were studied. The elongation minimum and strain ratesensitivity minimum occurred at each strain rate and the minimawere shifted to higher temperature with increasing strain rate. Theloss of ductility associated with dynamic strain aging was observedbetween 250~400 deg C. SEM observation revealed that thefracture surface of Zircaloy-4 nuclear fuel claddings was ductileirrespective of strain rate and temperature. The predicted strain ratesensitivity and elongation are in reasonably good agreement withexperimental data in the temperature region of the dynamic strainaging. In the temperature region of the flow stress plateau, thedecreases in the strain rate sensitivity due to dynamic strain agingresult in a low ductility. Above the temperature range of the flowstress plateau, the high strain rate sensitivity due to dynamic strainaging causes high ductility.