A model of the threshold stress intensity factor, KIH, for delayed hydride cracking of Zr–2.5Nb alloy

Abstract

An analytical model to predict a threshold stress intensity factor, K IH, for delayed hydride cracking of Zr–2.5Nb alloy was developed based on a criterion to fracture hydrides: σ max A( r c)+ σ h( r c)= σ f h. The hydride platelet is assumed to cover a process zone ahead of the crack tip. By using the cohesive zone model and von Mises yield criterion at the boundary of the cohesive zone, the cohesive stress and the cohesive zone length (or the process zone length) were determined. The maximum stress and a critical distance in the process zone, corresponding to its occurrence, were obtained by assuming an elastic and linearly plastic materials with a constant tangent modulus, E t. The feasibility of the developed K IH model was discussed by comparing the predicted K IH with the measured one by accounting for a temperature dependence of K IH.