Hydride embrittlement and irradiation effects on the hoop mechanical properties of pressurized water reactor (PWR) and boiling-water reactor (BWR) ZIRCALOY cladding tubes:: Part III.: Mechanical behavior of hydride in stress-relieved annealed and recrystallized ZIRCALOYs at 20 °C and 300 °C

This series of articles on the hydride embrittlement effect in ZIRCALOYs consists of three parts. Part III deals with the mechanical properties of some hydrides in some ZIRCALOYs at two temperatures (20 degreesC and 300 degreesC). The damage and fracture mechanisms were investigated by SEM in-situ testing. Based on the scanning electron microscopy (SEM) in-situ observations and the mechanical modeling, the mechanical behavior of hydrides confined within a matrix was determined. The hydrides can undergo significant plastic deformation under certain conditions. They have higher strength than the surrounding ZIRCALOY matrix. The radiation effect on hydrided ZIRCALOYs and the combined effect were also discussed. Part I is concerned with the general influence of hydrides on the mechanical properties and damage and fracture mechanisms of ZIRCALOYs at two temperatures (20 degreesC and 300 degreesC) and for hydrogen content up to 4500 ppm. In Part 11, the morphology and crystallographic structure of hydrides in two ZIRCALOYs are examined at different magnifications and by different techniques (SEM, transmission electron microscopy (TEM), and X-ray diffraction) as a function of their pre-heat treatment and their hydrogen content.