Coleman, C. E.,Rodgers, Douglas Keith.2009-03-232009-03-2319921992Source: Masters Abstracts International, Volume: 33-04, page: 1328.9780315936089http://hdl.handle.net/10393/7494http://dx.doi.org/10.20381/ruor-15370Delayed Hydride Cracking (DHC) occurs in Zr-2.5Nb when certain requirements are met. The mechanism of DHC consists of diffusion of hydrogen to a stress concentrator, such as a crack-tip, precipitation then fracture of a hydride at the crack-tip, and repetition of the process; the crack advances in steps. Incubation times, to the start of cracking and crack-tip hydride morphologies have been measured in pre-cracked cantilever beam specimens tested at applied K$\rm\sb I$'s up to 20 MPam$\sp{1/2}$ and temperatures ranging from 100 to 250$\sp\circ$C. The incubation time for DHC was found to vary inversely with DHC velocity. Contrary to previous research, the incubation time is highly variable, even for a given temperature and applied K$\rm\sb I,$ and the crack-tip hydride morphology is much more complicated than the simple model of a single hydride at a crack-tip.159 p.Engineering, Mechanical.Thesis