A Study on the Hot Deformation Behavior of 47Zr-45Ti-5Al-3V Alloy with Initial Lamellar α Structure

Abstract

The hot deformation behavior of the 47Zr-45Ti-5Al-3V (wt pct) alloy with initial lamellar α structure was investigated by compression tests in the temperature range of 823 K to 1073 K (550 °C to 800 °C) and strain rate range of 10⁻³ to 10⁰ s⁻¹. In the α + β phase field, the flow curves exhibited a continuous flow softening. The extent of flow softening first decreased with increasing strain rate from 10⁻³ to 10⁻¹ s⁻¹, and then increased with further increasing strain rate to 10⁰ s⁻¹. In the single β phase field, the flow curves exhibited a pronounced stress drop at the very beginning of deformation at low temperatures and high strain rates. The magnitude of the stress drop increased with decreasing deformation temperature and increasing strain rate. At higher temperatures and lower strain rates, the flow curves exhibited typical characteristics of dynamic recrystallization. A hyperbolic-sine Arrhenius-type equation was used to characterize the dependence of the flow stress on deformation temperature and strain rate. The activation energy for deformation at different strains was calculated. In the α + β phase field, the activation energy for deformation increased from 333 to 355 kJ/mol with increasing strain, and then decreased to 312 kJ/mol. In the single β phase, the activation energy for deformation decreased from 169 to 136 kJ/mol with increasing strain.