An EBSD investigation on the columnar grain growth in non-oriented electrical steels assisted by strain induced boundary migration

• Published in: Materials letters Vol. 252; pp. 42 - 46
• Main Authors: Gutiérrez Castañeda, E.J., Hernández Miranda, M.G., Salinas Rodríguez, A., Aguilar Carrillo, J., Reyes Domínguez, I.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-10-2019; Elsevier BV
• Subjects: Annealing; Annealing time; Cold rolling; Columnar growth; Deformation effects; Electrical steels; Electron backscatter diffraction; Grain boundary migration; Grain growth; Hot rolling; Magnetic properties; Materials science; Misalignment; Morphology; Non-oriented electrical steels; Plastic deformation; Steels; Strain induced boundary migration (SIBM); Strain induced boundary migration (SIBM); Plastic deformation; Columnar growth; Annealing time; Non-oriented electrical steels
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2019.05.073

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•Columnar grain growth in “hot-rolled GNO electrical steels” investigated by grain average misorientation and electron backscattering diffraction.•Columnar growth is driven by the strain induced boundary migration mechanism due to a strain gradient along the steel thickness.•Growing of surface ferrite grains leads to the formation of a continuous layer with lower strain inverting the strain gradient.•Strain gradient along the steel thickness is reduced for high deformation levels.•Higher plastic deformations lead to primary recrystallization and equiaxial grains due to a more homogeneous deformation along steel thickness.
Recent studies regarding the development of high efficiency grain non-oriented (GNO) electrical steels demonstrate that development of columnar-grained microstructures prior to cold rolling is an efficient method to improve the magnetic behavior of the final product. However, the columnar morphology obtained by annealing of the hot-rolled bands was not developed after further processing by cold rolling and final annealing. Understanding the effects of plastic deformation on the development of such microstructures will help to promote them during the final annealing and improve even more the magnetic behavior of these materials. The present research reports the effects of small plastic deformations (0–25%) and annealing time (10–180 min) on the development of columnar microstructures in GNO electrical steels. The columnar grain growth is explained in terms of the strain induced grain boundary migration (SIBM) mechanism, based on the changes in the grain average misorientation (GAM) maps obtained by electron backscattering diffraction (EBSD).