Effect of hydrogen on the creep behavior of Zr–2.5%Nb alloy at 723 K

Increased plasticity is reported in Ti alloys, stainless steels and Pd by the introduction of hydrogen. The dissolved hydrogen in zirconium and its alloys which have similar properties as those of titanium and its alloys, can modify the creep properties of the matrix. Hydrogen, formed during the corrosion reaction of Zr–2.5%Nb pressure tube, in a CANDU design nuclear reactor, with the coolant can ingress into the metal matrix. This absorbed hydrogen can lead to an unexpected increase in length and in diameter of the pressure tube. In order to evaluate the effect of hydrogen on the creep behavior of the pressure tube material, tensile specimens with longitudinal and transverse orientations were hydrided to 65 and 160 wt ppm and creep tested at 723 K over a stress range. The combined influence of hydrogen and specimen orientations on creep rate is evaluated, and an attempt is made to explain the results using the deformation mechanisms reported in literature.