One of the main limiting factors on the lifetimes of nuclear fuel rod claddings is the formation of hydrides and associated detrimental effects on mechanical properties. In this study, we examined the behavior of hydrides in zirconium and zircaloy-4 after tensile stress is applied to determine whether the more ductile??-ZrH phase was stabilized by the mechanical stress. We did not find a significant increase in the ratio of ?-ZrH phase to ?-ZrH1.5 phases after tensile stress is applied in previously hydrided metals. Previous reports indicate that this stabilization does occur when zircaloy is stressed and hydrided simultaneously, indicating that the formation of the ?-ZrH phase may reverse upon relaxation or may require the stress in-situ during the hydriding process to form in significant quantities.