Dynamic Recrystallization Model of Ultrafine-Grained Pure Zirconium Refined by Compounding

An ultrafine-grained (UFG) pure zirconium refined by compounding with grain size of 200 similar to 250 nm was subjected to a unidirectional compression test using a Gleeble-3800 thermal simulation tester at the temperatures of 300 similar to 450 degrees C and strain rates of 0.001 similar to 0.05 s(-1). Experimental results show that the hot process parameters influence the flow stress of the UFG pure zirconium. Experimental data and microstructure analysis reveal that dynamic recrystallization is more likely to occur at higher deformation temperatures and lower strain rates. The critical strain model of UFG pure zirconium was established, and the relationship between the temperature-compensated strain rate factor Z and epsilon(c) (critical strain), sigma(c) (critical stress), epsilon(p) (peak strain) and sigma(p) (peak stress) was obtained. The constitutive model of UFG pure zirconium was confirmed based on dynamic recrystalization (DRX) volume fraction and proven to occur at a strain of 0.1 to 0.45.