Effects of Initial Grain Orientation and Annealing Parameters on Grain Size, Texture, and Magnetic Properties of Ultra-Thin Grain-Oriented Silicon Steel

In this paper, 0.075 mm gauge ultra-thin grain-oriented silicon steel (UTGO) was prepared using a commercial 0.27 mm gauge glassless grain-oriented silicon steel (GlGO) plate as initial material. The influence of textures of the initial samples on deformed and recrystallized grain orientations and magnetic properties of the prepared samples of UTGO was investigated. The samples with various initial textures were cut from the GlGO plate along rolling direction (RD) with different deviated angles ranging from 0° to 35°, namely G0-G35. After being cold rolled to 0.075 mm, the samples were subjected to annealing at 900 °C and 700 °C for various periods of time. Results show that with increase in deviation angles, the cold rolled textures transited from {111}<112> to {223}<362> and ultimately to {112}<110>. Meanwhile, the required annealing texture component of Goss ({011}<100>) and η-fiber texture ({0kl}<100>, k, l≠1) also decreases. It indicates that the initial samples with sharp Goss texture (G0) strongly promotes recrystallized <100>//RD texture (η-fiber + Goss texture), which is required of UTGO with high magnetic induction along RD but also with high iron loss in this condition. With increasing annealing time, the iron loss reduces, but it poses unfavorable effect on the formation of η-fiber texture and magnetic induction. Thus, iron loss and magnetic induction are inversely related. Therefore, it is necessary to find the initial state required for the balance of high magnetic induction and low loss of UTGO, which is the ideal combination of sharp <100>//RD texture (η-fiber + Goss texture) and appropriate recrystallized grain size. Specifically, evolution of texture is strongly dependent on initial grain orientations which greatly affects the deformed microstructure and nucleation behaviors. It implies that the magnetic properties of UTGO could be improved by controlled rolling and annealing process even when one uses low cost and low permeability raw materials with weaker Goss texture to produce economical and high-performance UTGO steel.