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

Effects of Annealing Temperature on Recrystallization Texture and Microstructure Uniformity of High Purity Tantalum

“…Meanwhile, these initial nuclei were thermodynamically unstable and prefer to adjust their orientations favorably to grow when they encounter non-uniformly distributed energy in deformed grain or {111}-{100} boundaries, which can be attributed to growth selection [7,25], resulting in the appearance of grains with random orientation. However, at high temperature, {111} matrix possessed a much superior recrystallization ability compared with {100} matrix, not only due to the rapid migration of {111} grain boundaries [26] but also because of the high stored energy to drive the migration. The fast migration of {111} grain boundaries can swallow other randomly orientated grains and significantly increase the {111} grain size, causing the increase of {111}<uvw> texture intensity.…”

Grain Refinement by Rapid Transformation Annealing of Cold Rolled Low Carbon Steels

“…Equation 2 has often been employed to determine the recrystallized fractions in sub-critical annealing treatments of cold rolled steel strips [10,13,14]. It has been employed here to determine the softened (recrystallized or α-γ-α transformed) ferrite fractions at each temperature.…”

Cold Rolled Microstructure and Its Evolution during Recovery and First Recrystallisation Stages in Low Carbon Steels

“…The orientations at the transition band are close to the {111}<1-10> γ/α fibre, with the rotation axis close to the <1-10>, and having a bigger scatter around the {111}. Previous OIM results obtained in cold rolled ELC and IF samples, indicate that the quality factor inside the grains with orientations belonging to the γ fibre is significantly lower than inside grains belonging to α fibre [21,22]. This result is related to a heterogeneous distribution of stored energy after cold working depending on the grain orientation [23,24].…”

“…Evolving from this matrix, an important amount of recrystallised grains can be distinguished. Aspects of orientation-dependent grain growth in ELC and IF steels during continuous annealing were reported by the authors [21,22].…”