Recrystallization of the ultradispersed structure of pure iron formed at different stages of the deformation-induced strain hardening

Abstract

Grain growth has been investigated during heating of pure single-phase iron with an ultra-dispersed structure of different types under conditions which exclude retardation by impurity atoms or by dispersed particles. The rate of growth mainly depends on the type of boundaries formed in this structure during a preliminary treatment, which determines the different kinetics of primary recrystallization. The thermal stability of submicrocrystalline (SMC) structure increases with increasing degree of deformation. In contrast to the materials with an impurity and carbide retardation, in pure iron an intermediate annealing of the SMC structure, which usually leads during low-temperature recrystallization to the formation of a honeycomb structure, does not influence thermal stability. The formation of thermally activated centers of recrystallization has been found to occur during heating of iron with a uniform isotropic SMC structure at the temperature of the onset of the recrystallization of moderately deformed iron. The formation of a honeycomb structure does not lead to a considerable reduction in the accumulated strain energy, and, during further heating, thermally activated nuclei of recrystallization are formed.