Dynamic Recrystallization of Copper during Hot Torsion

Abstract

Tubular specimens of oxygen-free, high-conductivity copper have been deformed by hot torsion at 800° C (1073 K) (O.8T _m ) or at 950° C (1323 K) (0.9T _m ) at strain rates of 3.7–11.1 S⁻¹ to true strains of ∼ 30. The specimens were quenched to room temperature in 3 s under one of two conditions: stopping the deformation and then quenching immediately, or quenching followed quickly by stopping the deformation. The resulting structures were examined by optical and transmission electron microscopy. The specimens quenched after stopping the deformation had recrystallized statically (subsequent to deformation) during cooling. The specimens deformed without stopping until quenched had not recrystallized statically but retained the as-worked grains that formed by dynamic recrystallization (concurrent with deformation). Since these grains nucleated at different times during the deformation, they contained dislocation substructures of varying densities. The theories of dynamic and static recrystallization are discussed.