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

In this article, 0.075 mm gauge ultra-thin grain-oriented (UTGO) silicon steel was prepared using a commercial 0.27 mm gauge glassless grain-oriented (GlGO) silicon steel plate as the 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 the 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 the increase in deviation angles, the cold rolled textures transited from {111}
$\langle 112\rangle $
to {223}
$\langle 362\rangle $
and ultimately to {112}
$\langle 110\rangle $
. Meanwhile, the required annealing texture component of Goss ({011}
$\langle 100\rangle $
) and
$\eta $
-fiber texture ({
$0kl$
}
$\langle 100\rangle $
,
$k, l \ne 1$
) also decreases. It indicates that the initial samples with sharp Goss texture (G0) strongly promote recrystallized
$\langle 100\rangle $
//RD texture (
$\eta $
-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 an unfavorable effect on the formation of
$\eta $
-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
$\langle 100\rangle $
//RD texture (
$\eta $
-fiber + Goss texture) and appropriate recrystallized grain size. Specifically, the 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 processes even when one uses low-cost and low-permeability raw materials with weaker Goss texture to produce economical and high-performance UTGO steel.