Charpy impact test of oxidized and hydrogenated Zircaloy using a thin strip specimen

The impact properties of an oxidized and a hydrogenated Zircaloy have been studied separately by using a strip Charpy V-notch specimen, which has 1 m in thickness and 4 mm in width, with an instrumented Charpy machine. The aim was to examine influences of the oxide formed on the strip specimen and the hydride preferentially oriented in the strip specimen on a fracture process (properties of crack initiation and propagation) of Zircaloy strip. The fracture process was analyzed by separation of the absorbed energy calculated from a load-displacement curve. The impact property of the hydrogenated Zircaloy strip was mainly influenced by a crack propagation. The large secondary crack generated by a fracture of the hydride was observed in an inner part of fracture surface. For oxidized Zircaloy, the oxide layer and a high oxygen concentration layer were formed on the specimen surface. A crack initiation energy of the specimen oxidized for 60 min at 973 K decreased by 30%, compared with that of the as-received one. The high oxygen concentration layer on the surface constrained a deformation of the Zircaloy matrix at a notch root. (author)