High-Temperature Deformation Constitutive Relationship of Zr-Sn-Nb Alloy for Nuclear Power

Zr-Sn-Nb zirconium alloys are widely used in the field of nuclear power instead of traditional zirconium alloys and can be used as structural materials for nuclear power fuel assemblies. In this paper, the constitutive relation of high temperature plastic deformation of Zr-Sn-Nb alloy for nuclear power is described. Gleeble-3800 thermal simulation tester was used to conduct compression tests at different temperatures (450∼700°C) and deformation rates (0.01∼10s−1), stress-strain curves under different deformation conditions were drawn based on stress-strain data. According to the analysis of flow stress curve types, Zr-Sn-Nb alloy shows obvious temperature sensitivity and strain rate sensitivity. Under the condition of low temperature and high strain rate, the power dissipation efficiency is calculated according to Murty instability discriminant. Zirconium alloy material shows flow instability due to the formation of adiabatic shear band. In order to control the successful rolling of microstructure, careful process design must be carried out to avoid the flow instability zone. Based on the types of stress-strain curves, the curves are divided into work hardening stage and dynamic recovery (DRV)/ dynamic recrystallization (DRX) stage. A piecewise constitutive model is established, which can accurately predict the machining properties of Zr-Sn-Nb alloy for nuclear power.