Evolution of Microstructure and Texture in Low-Carbon Grain Non-Oriented Electrical Steels Processed from Solid-State Columnar Microstructures

Decarburizing annealing in the two-phase (ferrite/austenite) region is a known method to provide columnar grain growth in grain non-oriented (GNO) electrical steels. This method involves a long-term preliminary annealing in vacuum and subsequent decarburizing annealing in a wet hydrogen atmosphere. Such method has been used to modify the deformation and recrystallization textures of cold-rolled and temper-rolled electrical steels to improve their magnetic behavior. In the present work, columnar microstructures were obtained, but in hot-rolled GNO electrical steels, and without using a preliminary vacuum annealing. Changes in microstructure, texture, and energy losses obtained during further processing were followed by optical microscopy, electron backscatter diffraction and magnetometry. Results show that samples subjected to modification exhibit lower energy losses than unmodified samples, which is attributed to texture improvement, carbon reduction and grain size increment caused by the solid-state columnar growth produced in hot-rolled bands.