Hot deformation behavior and processing map of ultrafine-grained pure zirconium refined by compounding

Abstract

An ultrafine-grained (UFG) pure zirconium(Zr) refined by compounding with a size of Φ4 × 6 mm was subjected to a unidirectional compression test using a Gellble-3800 thermal simulation tester at the temperature of 300 °C–450 °C and a strain rate range of 0.001–0.05 s ^−1 . Experimental results showed that the flow stress of UFG pure Zr refined by compounding is highly sensitive to temperature and strain rate, and the peak stress decreases with increase in deformation temperature and increases with increase in strain rate. The Arrhenius constitutive equation based on the experimental data can effectively predict peak stress in actual thermal deformation, The correlation coefficient between the actual value and the predicted value can reach as high as 0.99722. With the increase in deformation temperature and the decrease in strain rate, the UFG pure Zr refined by compounding otably undergoes dynamic recovery and dynamic recrystallization. These findings are based on the hot processing map and microstructure characteristics of UFG pure Zr refined by compounding. The optimal hot-working windows are determined to be in the deformation temperature of 320 °C–360 °C with strain rate of 0.005–0.01 s ^−1 and the deformation temperature of 410–450 °C with strain rate of 0.003–0.01 s ^−1 .

Keywords

• composite deformation ultrafine-grained pure zirconium
• arrhenius constitutive
• hot processing diagram
• microstructure
• dynamic recrystallization