Hot Deformation of Uranium in the α, β, and γ Phases

Abstract

Uniaxial compression tests were carried out on uranium from 0.003 to 5 s⁻¹ and 723 K to 1123 K (450 °C to 850 °C) covering the α, β, and γ phases. The flow stress in the β phase was the highest and that in the γ phase the lowest. The strain rate sensitivity (SRS) was plotted as an iso-SRS contour map. The phase revealed dynamically recrystallized grains at 0.1 s⁻¹ and 873 K (600 °C) with SRS = 0.14. The γ phase showed a high SRS domain of 0.25 at 0.1 to 1 s⁻¹ and 1073 K to 1123 K (800 °C to 850 °C). The activation energy of deformation matched that of self diffusion for α and γ phases, and was higher for the β phase. The stress exponents for all the phases were in the 4.5 to 7 range suggesting dislocation controlled deformation. It was suggested that U should be hot deformed in the α phase in the 873 K to 923 K (600 °C to 650 °C) and 0.1 s⁻¹ range.