Effect of Hydrogen Concentration on the Threshold Stress Intensity Factor for Delayed Hydride Cracking in Zr-2.5Nb Pressure Tubes

The Zr-2.5Nb pressure tubes of CANDU reactors are susceptible to a crack initiation and growth mechanism known as Delayed Hydride Cracking (DHC), which is a repetitive process that involves hydrogen diffusion, hydride precipitation, hydrided region formation and fracture at a flaw or crack tip. The threshold stress intensity for DHC initiation from a crack, KIH , is an important material parameter for assessing DHC initiation from flaws in …