Classification and properties of silicon steel sheets

Jun 22, 2022

Silicon steel sheet for electrical purposes is commonly known as silicon steel sheet or silicon steel sheet. As the name suggests, it is an electrical silicon steel with silicon content up to 0.8%-4.8%, which is made by hot and cold rolling. Generally, the thickness is less than 1mm, so it is called thin plate. In a broad sense, silicon steel sheet belongs to plate, which is an independent branch due to its special use.

Silicon steel sheet for electrical engineering has excellent electromagnetic properties and is an indispensable and important magnetic material in the power, telecommunication and instrument industries.

(1) Classification of silicon steel sheets

A. Silicon steel sheet can be divided into low silicon and high silicon according to its silicon content. Low silicon wafer contains less than 2.8% silicon, which has certain mechanical strength and is mainly used to manufacture motor, commonly known as motor silicon steel sheet; The silicon content of high silicon chip is 2.8%-4.8%. It has good magnetism, but it is brittle. It is mainly used to manufacture transformer iron core, commonly known as transformer silicon steel sheet. There is no strict boundary between the two in practical use, and large motors are usually made of high silicon wafers.

B. According to the production process, it can be divided into hot rolling and cold rolling, and cold rolling can be divided into grain non orientation and grain orientation. Cold rolled sheets have uniform thickness, good surface quality and high magnetic properties. Therefore, with the development of industry, hot rolled sheets tend to be replaced by cold rolled sheets (China has clearly requested to stop using hot-rolled silicon steel sheets, that is, in the early stage, "cold instead of hot").

(2) Performance index of silicon steel sheet

A. Low iron loss. As an important indicator of quality, all countries in the world classify the brand by iron loss value. The lower the iron loss, the higher the brand and the higher the quality.

B. High magnetic induction. Silicon steel sheet with high magnetic induction can be obtained under the same magnetic field. The volume and weight of motor or transformer iron core manufactured with it are small, which can relatively save silicon steel sheet, copper wire and insulating materials.

C. High stacking factor. The surface of silicon steel sheet is smooth, flat and uniform in thickness, and the stacking coefficient of manufacturing iron core is improved.

D. Good punching performance. This is more important for manufacturing iron cores of small and micro motors.

E. The surface has good adhesion and weldability to the insulating film.

F. Magnetic aging

G. Silicon steel sheets shall be delivered after annealing and pickling.

(1) Hot rolled silicon steel sheet for electrical purposes (gb5212-85)

The hot-rolled silicon steel sheet for electrical purposes is made of silicon iron soft magnetic alloy with low carbon loss and is hot rolled into a sheet with a thickness of less than 1mm. Hot rolled silicon steel sheet for electrical purposes is also called hot rolled silicon steel sheet.

Hot rolled silicon steel sheets can be divided into low silicon (Si ≤ 2.8%) and high silicon (Si ≤ 4.8%) steel sheets according to their silicon content.

(2) Cold rolled silicon steel sheet for electrical purposes (gb2521-88)

It is made of electrical silicon steel containing 0.8%-4.8% silicon by cold rolling.

Cold rolled silicon steel sheet can be divided into two kinds of steel strip: grain non oriented and grain oriented. Cold rolled electrical steel strip has the characteristics of flat surface, uniform thickness, high stacking coefficient and good punching performance, and has higher magnetic induction and lower iron loss than hot-rolled electrical steel strip. Using cold strip instead of hot rolled strip to make motor or transformer, its weight and volume can be reduced by 0%-25%. If cold-rolled oriented strip is used, the performance is better. Using it instead of hot-rolled strip or low-grade cold-rolled strip can reduce the power consumption of transformer by 45%-50%, and the working performance of transformer is more reliable.

For manufacturing motors and transformers. Generally, grain oriented cold rolled strip is used as a state of motor or welding transformer, etc; Grain oriented cold rolled strip is used as the core of power transformer, pulse transformer and magnetic amplifier.

Specification and dimension of steel plate: thickness: 0.35, 0.50, 0.65mm, width: 800-1000mm, length: ≤ 2.0m.

(3) Hot rolled silicon steel sheet for household appliances (gbh46002-90)

The brand of hot-rolled silicon steel sheet for household appliances is represented by J (home) d (electricity) r (hot rolling), namely JDR. The number after JDR is the iron loss value *100, and the number after the horizontal line is the steel plate thickness (mm) *100. The requirements for electromagnetic properties of hot-rolled silicon steel sheets for household appliances can be slightly lower, and the minimum iron loss value (p15/50) is 5.40w/kg. Generally, it is delivered without washing.

It is used for differential motors of various electric fans, washing machines, vacuum cleaners, range hoods and other household appliances.