ISIJ International
Online ISSN : 1347-5460
Print ISSN : 0915-1559
ISSN-L : 0915-1559
3D Crystal Orientation Mapping of Recrystallization in Severely Cold-rolled Pure Iron Using Laboratory Diffraction Contrast Tomography
Jun SunChristian HolznerHrishikesh BaleMiho TomitaNicolas GueninchaultFlorian BachmannErik LauridsenToru InagumaMasao Kimura
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JOURNALS OPEN ACCESS Advance online publication

Article ID: ISIJINT-2019-405

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Abstract

The mechanism of recrystallization texture development of cold-rolled metal and steel largely depends on the material chemical composition, cold-rolling reduction, and annealing treatment conditions. To clarify the mechanism, it is important to identify the locations where recrystallization starts and progresses within cold-rolled materials.

Using laboratory diffraction contrast tomography (LabDCT), three-dimensional (3D) crystal orientation mapping corresponding to different stages of recrystallization has been successfully performed for pure iron sheets that were severely cold-rolled and heated at different temperatures.

In cold-rolled iron with 99.2% reduction, the deformation texture was a strong α-fiber (RD//<110>). During annealing in the temperature range of 773–973 K, recrystallized grains were formed with textural components of {100}, {211}, {111} and {411}, and the α-fiber changed to the {100}<012> component. Recrystallized grains were generated at rather random locations within the sample. The size of recrystallized grains in the center region was 20–30% larger than that in the surface region. These results suggest that the nucleation is driven by the large strain caused by severe rolling. The number of recrystallization sites was larger in the surface region than in the center region and the competition of selective growth among recrystallized grains was more severe in the surface region, resulting in a smaller grain size.

The volume data of the 3D crystal orientation mapping obtained by LabDCT provided crucial information for understanding the recrystallization mechanism including the nucleation and/or selective growth.

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© 2019 by The Iron and Steel Institute of Japan
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