Effect of irradiation on the strength, ductility, and defect sensitivity of fully recrystallized zircaloy tube

The effect of irradiation on the strength, ductility, and defect sensitivity of recrystallized Zircaloy has been investigated. Plane strain burst specimens were irradiated to fast-neutron fluences between 2.4*1024 and 10.8*1024 n/m2, E>1 MeV. A few of the specimens contained well-characterized internal surface flaws. It was shown that the effect of fluence on yield stress could not be described by the theoretical relationship sigma.sigma/sub O/+A[1-exp(-B phi t)]/sup 1/2/. As an alternative the empirical relation sigma.sigma/sub O/+A( phi t)/sup 1/n/ could be used to describe the result. It was found that irradiated Zircaloy is very sensitive to defects with pinhole failures occurring after very small plastic strains. The defect sensitivity could be explained as a combination of the loading conditions and the absence of strain hardening in the irradiated material. 11 refs