The influence of crack tip modeling on the prediction of critical crack length in pressure tube alloys

The need for accurate prediction of critical crack length (CCL) for materials exhibiting stable crack growth prior to the onset of fast fracture is demonstrated by accurately predicting CCL from Irwin's approach by simply varying the geometry factor to accommodate changes in crack tip shape for various heat treatments applied to the Zr-2.5 wt.% Nb (Zr-Nb) alloy used in pressure tubes for nuclear power reactors. The accuracy of the predictions is shown by experiments on 17 mm compact specimens for three heat treatments. The measured crack lengths were confirmed by applying the predictive capability of Irwin's approach to earlier work on this material and the sister pressure tube material, Zr-Sn