Effect of strain rate on microstructure evolutions and mechanical properties of cryorolled Zr upon annealing

The effect of rolling strain rate on the microstructures of cryorolled Zr before and after 450 degrees C annealing has been investigated. With increasing strain rate, dislocation density increases and dislocation configuration changes from dislocation cells or tangles to dislocation lamellas in the cryorolled Zr, resulting in different microstructures after annealing. High-density dislocations with the lamella configurations produced at a high strain rate of (epsilon) over dot = 2.24 s(-1) lead to a multimodal grain microstructure in the annealed Zr sample. The multimodal-structured Zr exhibits a simultaneous enhancement of strength and toughness as compared with the samples cryorolled at low strain rates and the coarse-grained Zr. (C) 2011 Elsevier B.V. All rights reserved.