Book Description

The effects of hydrogen concentration and hydride morphology on the tensile properties of alpha-annealed and beta-quenched Zircaloy have been experimentally determined at 78 and 500 F for unnotched and notched specimens. Three hydrogen levels, approximately 15, 275, and 550 ppm by weight, with the precipitated hydride either predominantly at grain boundaries or uniformly distributed within the grains, were investigated. Generally, the effects of hydrogen are not deleterious at 500 F, and at 78 F the deleterious effects are less pronounced when the hydrides are uniformly distributed rather than concentrated at grain boundaries. An evaluation of the integrity of Zircaloy-2 containing hydrogen is made based upon the measured ductility and notch sensitivity. Fracture of hydrided Zircaloy-2 under tension was observed metallographically to proceed by initiation of cracks in the hydride platelets and by propagation through the ductile metal.