Effect of Specimen Geometry, Orientation and Temperature on the Impact Toughness of Zr-2.5Nb Pressure Tube

Impact toughness of Zr-2.5Nb pressure tube material was evaluated as a function of specimen geometry, orientation and test temperature. Two types of samples were used. Curved impact specimens were machined directly from the tube section thereby retaining the pressure tube curvature and flat impact specimens were machined from a flattened tube section subjected to stress relieving treatment. In both the cases the specimen thickness was the actual pressure tube thickness that is 3.5 mm and the other dimension of the impact specimen was 55 mm × 10 mm. The tests were carried out for both as-received and hydrided pressure tubes between room temperature and 300 °C. As the Zr-2.5Nb pressure tube material is anisotropic, the studies were also carried out using specimens with crack growth either along axial or along transverse direction of the tube. The paper describes the results generated and discusses the materials impact toughness behaviour under different conditions.