1/Influence of chemical composition:
The basic composition of silicon steel is composed of three major elements. The first category is basic alloying elements such as Si, Al, Mn; the second category is impurity elements such as C, S, N, O, Ti, Zr; and the third category is trace elements such as Sb, Sn.
- The influence of the first type of elements
Si, Al and Mn are useful alloying elements that can reduce the magnetic anisotropy constant K1 and the saturation hysteresis elastic constant λs, and make magnetization easier, so Ph decreases. In addition, these elements can also increase resistivity, so Pe decreases. Therefore, adding the content of the first type of elements can significantly reduce iron loss. But when these elements are too high, the material becomes hard and brittle and cannot be cooled.
- The influence of the second type of elements
Harmful elements such as C, S, N, O, Ti, Zr, etc. The presence of these elements can form small dispersed carbides, sulfides, nitrides and oxides in steel, which prevents the growth of finished annealed grains and is unfavorable to magnetism, so steel The lower the content of these elements, the better.
- The influence of the third type of elements
Adding a small amount of Sb to non-oriented silicon steel, Sn improves the texture of the non-oriented silicon steel sheet after recrystallization annealing, so that the favorable texture components of (100) and (110) are significantly added, so (111) is significantly reduced, and then Reduce iron loss and improve magnetic induction. Adding a small amount of these elements can suppress the formation of internal oxide and nitride layers and improve magnetic properties.
2/Grain size
The grain size is small, the amount of grain boundaries is small, the domain wall movement resistance is small, and the hysteresis loss is reduced. On the other hand, the grain size is large, the magnetic domain size increases, and the eddy current loss and abnormal loss increase. Therefore, there is an appropriate critical grain size to reduce the total iron loss.
-Impurities, inclusions and internal stresses
Inclusions and impurity elements in non-oriented silicon steel sheets should be reduced as much as possible, which is a more important measure to improve the magnetism. Not only do they prevent domain wall motion to add hysteresis losses and coercivity, but they also make magnetization difficult because of the drop in surrounding magnetostatic energy.
They also have a poor impact on particle growth and texture components. Any internal stress in the silicon steel sheet adds coercive force.
- Crystal texture
In grain-oriented silicon steel, advancing B8 significantly reduces hysteresis loss. For non-oriented silicon steel sheets, (100) plane texture is high, hysteresis loss and P15 are lower, followed by (110) texture, and (111) texture is the worst.
-Thickness of steel sheet
Usually, the thickness of the steel sheet decreases and the hysteresis loss increases. But as the thickness becomes thinner, the eddy current loss is significantly reduced. Therefore, the total iron loss also has an appropriate critical thickness. The surface of the steel sheet is smooth, the free magnetic poles on the surface are reduced, the static magnetic energy is reduced, the wall resistance is reduced, and the hysteresis loss and coercive force are reduced.