Flow behaviour of a modified Zr–2.5wt%Nb pressure tube alloy

Anisotropy in flow behavior of cold worked and stress-relieved Zr–2.5wt%Nb pressure tube alloy was characterized by performing tensile tests in the temperature range of 298–823 K and under a constant nominal strain-rate of ∼3 × 10−4 s−1. Results showed that both yield and ultimate tensile strengths of this alloy decreased gradually with increasing test temperatures, with a rapid fall in strengths above a temperature of 623 K. The tensile ductility did not change appreciably up to 673 K but increased rapidly above this temperature. A strain energy model was developed to explain the occurrence of dynamic strain ageing (DSA). Analysis of the true stress–strain behavior suggested that the flow hardening or softening behavior of this alloy can be expressed in the form of a constitutive relationship comprising of a constant, work-hardening term and a term representing flow softening due to recovery.