Tensile test of hydrided Zircaloy

In order to examine the influence of precipitated zirconium hydride on the failure behavior and fracture strength of light water reactor (LWR) cladding tubes, tensile tests were performed at room temperature for non-hydrided and hydrided Zircaloy sheet-type specimens with gauge section of 10.0X5.0 mm and thicknesses of 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mm. For specimens with thickness more than 2.5 mm, the ultimate tensile strength of the specimens appeared to be independent of thickness, which implied that plane strain condition was attained. For the specimen with 2.5 mm. thickness, the ultimate tensile strength increased slightly with increasing average hydrogen concentration. Through microscopic observation of the hydrided specimen surface by scanning electron microscopy (SEM), it was found that matrix/hydride debonding was not generated but that micro-cracks perpendicular to the axial direction were produced at the hydride layer. (C) 2002 Elsevier Science B.V. All rights reserved.