Email:
Phone/Whatsapp:+8618437960706
Oriented silicon steel, also known as grain-oriented silicon steel (GO), cold rolled grain-oriented silicon steel (CRGO), or transformer steel, is a soft magnetic polycrystalline metallic alloy. It has a silicon content of 3%, which increases the electrical resistivity, reduces eddy current losses, reduces coercive forces, and significantly improves the magnetic and electrical properties of iron. By controlling the rolling direction and rolling temperature, its grains are arranged along the rolling direction to form an oriented structure. The larger the size of grains lesser the losses and hence the grain size of GO silicon steel is larger than other normal steel.
In addition, according to the magnetic measurement, oriented silicon steel can be divided into two categories: common grain-oriented silicon steel and high magnetic induction grain-oriented silicon steel.
Common grain-oriented silicon steel: known as CGO silicon steel. Its magnetic induction is less than 1.88T.
High magnetic induction oriented silicon steel: known as HiB oriented silicon steel. Its magnetic induction is greater than 1.88T.
Grain-oriented silicon steel is usually smelted in an oxygen converter and goes through some necessary manufacturing steps, including:
Smelting — casting — slab heating — hot rolling (1100℃-1250℃) — normalizing — pickling — cold rolling (20℃-50℃) — heat treatment — paint MgO — annealing (700℃-900℃) — stretching annealed coating — magnetic measurement
*Note:
1. When alloying, the concentration levels of carbon, sulfur, oxygen, and nitrogen must be kept low, as these elements indicate the presence of carbides, sulfides, oxides, and nitrides. These compounds, even in particles as small as one micrometer in diameter, increase hysteresis losses while also decreasing magnetic permeability.
2. The silicon content of grain-oriented silicon steel is about 3%, the carbon mass fraction is 0.03%-0.05%, and the iron content is more than 95%. It also requires that the oxide inclusion content in the steel is low and that it must contain some kind of inhibitor (MnS, A1N). The function of the inhibitor is to prevent the growth of primary recrystallized grains and promote the development of secondary recrystallization, thereby obtaining high orientation. However the inhibitor itself is harmful to magnetism, so after completing the inhibitory effect, it must be purified and annealed at high temperature. When using second-phase inhibitors, the slab heating temperature must be increased to a solid solution of the original coarse second-phase particles, and then precipitate as fine particles during hot rolling or normalization to enhance the inhibitory effect.
3. The quality of GO silicon steel is measured in terms of lower losses of electrical current, which flows in the core. The proper design of the core and good quality of the core material do the best job in combination. Mainly the core losses are measured in Watts per Kg.
| Type | Grade | Thickness
(mm) |
Theoretical Density
(kg/dm3) |
Core Loss Value P17/50 (W/kg) | Magnetic Induction B8(T) |
| Common | B23G110 | 0.23 | 7.65 | 1.1 | 1.8 |
| B23G120 | 1.2 | 1.8 | |||
| B27G120 | 0.27 | 7.65 | 1.2 | 1.8 | |
| B27G130 | 1.3 | 1.8 | |||
| B30G120 | 0.3 | 7.65 | 1.2 | 1.8 | |
| B30G130 | 1.3 | 1.8 | |||
| B30G140 | 1.4 | 1.8 | |||
| B35G135 | 0.35 | 7.65 | 1.35 | 1.8 | |
| B35G145 | 1.45 | 1.8 | |||
| B35G155 | 1.55 | 1.8 | |||
| High magnetic induction | B23P090 | 0.23 | 7.65 | 0.9 | 1.87 |
| B23P095 | 0.95 | 1.87 | |||
| B23P100 | 1 | 1.87 | |||
| B27P095 | 0.27 | 7.65 | 0.95 | 1.88 | |
| B27P100 | 1 | 1.88 | |||
| B27P110 | 1.1 | 1.88 | |||
| 330P100 | 0.3 | 7.65 | 1 | 1.88 | |
| B30P105 | 1.05 | 1.88 | |||
| B30P110 | 1.1 | 1.88 | |||
| B30P120 | 1.2 | 1.88 | |||
| B35P115 | 0.35 | 7.65 | 1.15 | 1.88 | |
| B35P125 | 1.25 | 1.88 | |||
| B35P135 | 1.35 | 1.88 | |||
| High magnetic induction (Magnetic domain refinement) | B23R080 | 0.23 | 7.65 | 0.8 | 1.87 |
| B23R085 | 0.85 | 1.87 | |||
| B23R090 | 0.9 | 1.87 | |||
| B27R090 | 0.27 | 7.65 | 0.9 | 1.87 | |
| B27R095 | 0.95 | 1.87 |
1. High magnetic permeability. The grains of oriented silicon steel are arranged along the rolling direction to form an oriented structure, which optimizes the magnetic permeability of silicon steel and improves the efficiency and performance of electrical equipment.
2. High magnetic saturation. The grains of oriented silicon steel are arranged along the rolling direction to form an orientation structure, which improves the magnetic saturation induction intensity of the silicon steel and improves the output power of electrical equipment. This is essential for maintaining efficiency at varying loads.
3. Low hysteresis loss and eddy current losses. The grains of oriented silicon steel are arranged along the rolling direction to form an oriented structure, which reduces the hysteresis loss of silicon steel and reduces the energy consumption of electrical equipment.
4. Good processing performance. Grain-oriented silicon steel has low hardness, making it easy to process into electrical components of various shapes and sizes.
5. High electrical resistivity. Another important property of GO silicon steel is its high resistivity level. When silicon is added to the steel, it increases its resistivity which is otherwise quite low. This high resistivity then reduces the core losses by minimizing the eddy current components there. Thus, the overall transformer working gets optimized.
6. High mechanical elasticity. GO silicon steel offers exceptionally high mechanical elasticity. When used in the core of transformers or in any other motor or component, it adds to their life. And when the object comes under strain, the steel allows itself to retain its shape.
7. Reduced magnetostriction. It also has a very low level of magnetostriction, which leads to noise reduction. Magnetostriction is an important property as it helps in the conversion of electrical energy into mechanical energy, which is what transformers do. However high magnetostriction leads to high vibration levels. So, oriented silicon steel greatly helps lower magnetostriction, although it can’t be eliminated completely.
8. High lamination/stacking. GO laminations help minimize eddy currents and hysteresis losses in transformers. Additionally, it can lead to better and more compact designs and hence low material required. Usually, the stacking factor of oriented silicon steel often exceeds 95 percent of the theoretical maximum.
9. High magnetism. Compared with non-oriented silicon steel, oriented silicon steel has a strong magnetic property in the direction of rolling. This is because these crystals are aligned in the direction of cold rolling followed by a heat treatment process to form an oriented structure.
10. Cost-effectiveness. It also has a small size, excellent quality, and energy-saving properties, which can meet the needs of large nuclear power plants, hydropower plants, and thermal power plants. Under the same capacity, the size and weight of the transformer core made of oriented silicon steel are reduced so that silicon steel sheets, electromagnetic wires, and insulation materials can be saved.
Grain-oriented silicon steel is an indispensable soft magnetic material in the power industry, it can be used in the production of many different electrical equipment, including:
– Transformer. It can be used in manufacturing iron cores of various types of transformers like power transformers, distribution transformers, and pulse transformers.
– Current Rectifier.
– Shunt reactors.
– Large motor.
– Magnetic amplifier.
– Stabilizer.
– Power generators.
– Large rotating machines.
– Machine parts and automotive components.
– Directional magnetic field electrical products.
– High-voltage direct current (HVDC) transmission systems.
– Noise and vibration reduction.
