Mechanisms of recrystallization in cold and warm rolled low carbon steel and IF steel

Abstract

Strain localization is inevitable during the rolling process and this manifests itself most clearly in ferrite by the formation of shear bands and deformation and transition bands. Nucleation of recrystallisation is strongly associated with these microstructures and it is clear that nucleation is a process of subgrain growth out of these features. In this work it is shown that the γ fibre component of the rolling texture is most prone to strain localization, and that the rotation of materials in the shear bands and deformation bands is around <111>/ND, which gives rise to the {111}<hkl> rolling texture. For shear band and deformation band nuclei to dominate the final texture it is necessary to break the recrystallisation process into two stages, nucleation by growth of subgrains, and "impingement growth" of strings of small grains allowing invasion of all other material. The impingement growth provides, in effect, a super-nucleus, and these comprise strings of {111}<hkl> recrystallised material in cold and warm rolled IF steel, and also in a low carbon steel alloy suitable for box annealing.