Aspects of orientation-dependent grain growth in extra-low carbon and interstitial-free steels during continuous annealing

Abstract

The present work concentrates on the application of orientation imaging microscopy (OIM) based on the electron backscattered diffraction (EBSD) technique to the investigation of the microstructural evolution of an extra-low carbon (ELC) steel and a Ti-Nb-bearing interstitial-free (IF) steel, during continuous annealing. Aspects like the nucleation, the evolution of the recrystallized volume fraction and grain size of grains with different orientations, the interface area limiting recrystallized {111} regions, and the apparent growth rates have been considered. Different criteria have been applied in order to identify crystallites produced during annealing. During the first stages of annealing, a network of grain boundaries with misorientations higher than 10 deg is produced, mainly inside the deformed g-fiber grains. The crystallites formed within this network, free from cells or subgrains at their interiors, can be considered as potential nuclei. However, among all, only some of them become effective due to an important selection. The {111} recrystallized grains have a significant size and number advantage as compared with other texture components, and a hard impingement between clusters of {111} grains is produced during grain growth. The effect of grain growth behind the recrystallization front seems to be negligible as compared with the grain coarsening produced by the migration of this front, driven by the cold-work stored energy.

Sensitivity of Conventional and Non-destructive Characterization Techniques to Recovery and Recrystallization

“…3,12,[17][18][19] Recrystallized fraction is generally determined in the laboratory by metallographic observations, which are time consuming and often rather subjective, or by hardness measurements. Although hardness has provided good estimations of the recrystallized fractions in some extra low carbon (ELC) steels, 3,20,21) in others (including IF steels) the mechanical softening significantly deviated from the recrystallized fraction. 12,20,22,23) Higher softening fractions than recrystallized fractions are generally attributed to recovery concurrent with recrystallization.…”

“…Although hardness has provided good estimations of the recrystallized fractions in some extra low carbon (ELC) steels, 3,20,21) in others (including IF steels) the mechanical softening significantly deviated from the recrystallized fraction. 12,20,22,23) Higher softening fractions than recrystallized fractions are generally attributed to recovery concurrent with recrystallization. Moreover, NDT methods are applied at the plants as microstructurally blind quality control techniques and some information related to microstructure implicit in the signals is lost.…”

Recrystallization Texture of Cold-rolled Oxide Dispersion Strengthened Ferritic Steel

“…At last, we attempt to investigate why {110}<112> can not become dominance in non-ODS ferritic steels using the theory above: After similar cold-rolling reduction, the intensity of {001}<110> texture, which suppress the growth of nuclei, in conventional ferritic steels 6,7) is lower comparing with our ODS steel. The possible reason of this difference is that the initial texture in ODS ferritic steel is hot-extrusion texture, while the initial texture of conventional ferritic steels which is hot band texture.…”

“…Because of the tremendous industrial importance, many authors have studied the recrystallization behaviors of ferritic steels, such as interstitial free (IF) steel [6][7][8] and silicon steel. [9][10][11][12] Nevertheless, fewer works of recrystallization texture of cold-rolled ODS ferritic steels have been reported.…”

Effect of Mode of Rolling on Recrystallization Kinetics and Microstructure Evolution in Interstitial Free High Strength Steel Sheet

“…kinetics, microstructure evolution and texture development) in different grades of IF steel during straight (unidirectional) rolling. 2,4,11,13,[27][28][29][30][31] Similarly, there are studies on effect of cross rolling in non-oriented electrical steels, 32) pure iron 33) and many other metals/alloys [34][35][36] on microstructure and texture development. It has been reported in these studies [32][33][34][35][36] that change in the path of plastic deformation results in completely different sub-structure (i.e.…”