High temperature deformation behavior and constitutive model of Zirlo zirconium alloy

Abstract

In order to study the thermal deformation behavior of Zirlo alloy at ranges of 550-700 ℃ deformation temperature and 0.01-10 s-1 strain rate, the Zirlo alloy was subjected to compression under condition of isothermal and constant strain rate by using the Gleeble-3800 thermal simulated test machine. Through introducing strains on the basis of the Arrhenius type hyperbolic sine function equation, an Arrhenius constitutive model was developed based on strain compensation, and founded on a combination of dislocation density evolution causing work hardening model and phenomenological softening model, a segmented phenomenological constitutive model was constructed. The results show that the flow stress of Zirlo zirconium alloy increases with the decrease of temperature and the increase of strain rate, the flow stress exhibits higher temperature sensitivity at low strain rate, and flow stress curves separately exhibit characteristics as work hardening, dynamic recovery and dynamic recrystallization under different deformation conditions. Through error analysis, it was revealed that errors of the most stresses predicted by the Arrhenius constitutive model based on strain compensation are within 15%, which exhibits high accuracy. The maximum relative average absolute errors of the segmented phenomenological constitutive model are less than 3%, exhibiting an accuracy of over 97%. The segmented phenomenological constitutive model can accurately predict the stress-strain curve of the Zirlo alloy and has good expansibility; moreover, it can preliminarily predict the type of the stress-strain curve and has good practicability.

Keywords

• zirlo zirconium alloy
• thermal deformation behavior
• constitutive model
• strain compen-sation
• phenomenological constitutive relationship