Silicon steel sheet is a ferrosilicon soft magnetic alloy with extremely low carbon content, general silicon content is 0.5-4.5%. The addition of silicon increases the resistivity and maximum permeability of iron, and reduces coercivity, core loss (iron loss), and magnetic aging. Silicon Steel mainly used to make cores for various transformers, motors and generators. The performance indicators of silicon steel sheet including:

1.The iron loss of silicon steel sheet should be low

2. The magnetic sensitivity of silicon steel sheet should be high

3. The surface of the silicon steel sheet is required to be smooth, flat and uniform in thickness

4. The silicon steel sheet need have good adhesion and weldability

Generally, as the silicon content increases, the iron loss, punchability and magnetic induction decrease, and the hardness increases. The higher the working frequency, the greater the eddy current loss, and the thinner the silicon steel sheet should be.

Why use silicon steel to make transformers?

With strong magnetic permeability, silicon steel suitable for making transformer cores. In the energized coil,  the silicon steel core can generate a larger magnetic induction intensity, which can reduce the transformer volume.

As we know, during real application transformer is always in the AC state. The power loss exists not only in the coil resistance, but also in the core under the AC magnetization. Usually, iron loss is caused by "hysteresis loss" and "eddy current loss". Hysteresis loss is the iron loss caused by hysteresis during magnetization. The magnitude of this loss is proportional to the area enclosed by the material's hysteresis loop. The silicon steel hysteresis loop is narrow, and the transformer hysteresis loss is very small, which can reduce the heat generation greatly.

Silicon steel has the above advantages, why not we use a piece of silicon steel to integrally form thecore, but process it into sheets again? This is because the thin plate core reduces "eddy current losses". When the transformer is working, there is alternating current in the coil, and the magnetic flux generated by it is also alternating. This changing magnetic flux induces an induced current in the iron core.

The induced current generated in the iron core circulates in a plane perpendicular to the direction of the magnetic flux, so it is called eddy current. Eddy current losses also cause the core to heat up. To reduce eddy current losses, the transformer cores are laminated with silicon steel sheets insulated from each other, allowing eddy currents to flow through a narrow cross-section, thereby increasing the resistance on the eddy current path. At the same time, the silicon in the silicon steel increases the resistivity of the material and also reduces the eddy current.