Basic introduction
SiIiconsteelwithnon-orientedgrain
Silicon-iron alloy with very low carbon content. In the deformed and annealed steel sheet, its crystal grains are distributed randomly. The silicon content of the alloy is 1.5% to 3.0%, or the sum of the silicon and aluminum content is 1.8% to 4.0%. The products are usually cold-rolled plates or strips with nominal thicknesses of 0.35 and 0.5mm, which are mainly used to manufacture motors and generators.
Composition
The content of silicon, aluminum and manganese in steel is controlled within a certain range according to regulations, and the content of carbon, sulfur, nitrogen and oxygen is as low as possible. Different grades have different requirements for the content of these elements. Aluminum increases the strength and hardness of electrical steel and reduces ductility. However, the effect of aluminum on reducing ductility is not as obvious as that of silicon, and its effect is similar to that of silicon. Therefore, as the grade increases, the silicon content increases to about 3% without changing, and the aluminum content can gradually increase to 1%. The aluminum content of general grades is 0.3% to 0.6%. As the grade increases, the carbon, sulfur and manganese content is further reduced. The high-grade impurity content is: S<0.002%, C<0.003%, N2<0.002%, O2<0.002%. There is no need to decarburize after annealing to prevent the formation of internal oxide and internal nitride layers. In addition, Ti<0.005% and Zr<0.002% are required to prevent the formation of fine TiN, ZrN and TiC and hinder the growth of crystal grains.
Production process
Production process
Pre-desulfurization of molten iron is performed by adding Ca0+CaF: flux or rare earth elements and calcium for secondary desulfurization during converter blowing. Boiling molten steel undergoes vacuum treatment for decarburization and then further desulfurization. Ferrosilicon with low titanium and zirconium content is used for alloying. During continuous casting, it is sealed with argon gas and stirred by electromagnetic. The cast slab is sent to the hot rolling mill and placed in the slow cooling pit. The cast slab above 350C is charged into a heating furnace and heated to 1200±20C, the final hot rolling temperature is 850±20C, and the coiling temperature is 600±20C. The thickness of the hot-rolled sheet is 2.0-2.5mm. Steels with a silicon content of more than 2% generally use a one-shot cold rolling method, which is normalized at 900～1050C (1～3min) before cold rolling, and then cold rolled by a 20-high rolling mill. The secondary cold rolling method can also be used. After the first cold rolling, it is annealed at 830～870C (1～3min) in a continuous furnace with an atmosphere of 5%～20%H2+N2, and then subjected to 8%～10% critical deformation. Cold rolled to the thickness of the finished product. The final annealing is generally quickly heated to 850～860C (2～4min) annealing in a continuous furnace with a 20%H2+N2 atmosphere. If decarburization is required, it is best to use two-stage annealing. The first stage is decarburized at 800-850C in a wet atmosphere, and the latter stage is annealed at a higher temperature in a dry atmosphere for a short time to promote grain growth. During annealing, the tension in the furnace is best controlled below 2.9N/mm, which can reduce the magnetic anisotropy of the steel plate, and the ratio of the vertical and horizontal iron loss (P15) of the product is 1.1 to 1.3. After annealing, the steel plate is coated with a semi-organic insulating coating. Large motors that require high interlayer resistance can also be coated with inorganic salt insulation coatings.
Relationship
Relationship between non-oriented silicon steel sheet and oriented silicon steel sheet
Relationship between non-oriented silicon steel sheet and oriented silicon steel sheet:
1. Both are cold-rolled silicon steel sheets, but the silicon content is different. The silicon content of cold-rolled non-oriented silicon steel sheet is 0.5%-3.0%, and the silicon content of cold-rolled oriented silicon steel sheet is above 3.0%.
2. The production process and performance are different: non-oriented silicon steel sheet has relatively lower process requirements than oriented silicon steel sheet.
Non-oriented silicon steel sheets are hot rolled steel billets or continuous casting billets into coils with a thickness of about 2.3mm. When manufacturing low-silicon products, hot-rolled coils are pickled and then cold rolled to 0.5mm thickness in one pass. When manufacturing high-silicon products, the hot-rolled strip is pickled (or normalized at 800-850°C and then pickled), then cold-rolled to a thickness of 0.55 or 0.37mm, and annealed at 850°C in a hydrogen-nitrogen mixed atmosphere continuous furnace. It is cold rolled to 0.50 or 0.35mm thickness with a small reduction rate of 6-10%. Cold rolling with this low reduction ratio can increase the grain size during annealing and reduce the iron loss. Both cold-rolled sheets were finally annealed at 850℃ in a continuous furnace under a 20% hydrogen-nitrogen mixed atmosphere, and then coated with an insulating film of phosphate and chromate. After cold rolling to the thickness of the finished product, most of the steel strips in the supply state are 0.35mm and 0.5mm thick. The Bs of cold-rolled non-oriented silicon steel is higher than that of oriented silicon steel.
Oriented silicon steel sheet requires a low content of oxide inclusions in the steel, and must contain C0.03-0.05% and inhibitors (second-phase dispersed particles or grain boundary segregation elements). The role of the inhibitor is to prevent the growth of primary recrystallization grains and promote the development of secondary recrystallization, thereby obtaining high (110) [001] orientation. The inhibitor itself is harmful to magnetism, so after the inhibition is completed, it must be subjected to high-temperature purification annealing. When the second phase inhibitor is used, the heating temperature of the slab must be increased to make the original coarse second phase particles solid solution, and then the fine particles will be precipitated during hot rolling or normalization in order to enhance the inhibition effect. The thickness of the cold rolled product is 0.28, 0.30 or 0.35mm. The cold-rolled oriented thin silicon steel strip is made of 0.30 or 0.35mm thick oriented silicon steel strip, which is then pickled, cold rolled and annealed. Compared with cold-rolled non-oriented silicon steel, oriented silicon steel has much lower loss than non-oriented silicon steel, and has strong magnetic directionality; it has superior high permeability and low loss characteristics in the rolling direction of easy magnetization. The iron loss of the oriented steel strip in the rolling direction is only 1/3 of the transverse direction, the magnetic permeability ratio is 6:1, and the iron loss is about 1/2 of that of the hot-rolled strip, and the magnetic permeability is 2.5 times of the latter. .
3. Performance and use: Due to the different performance characteristics of the two, there is a difference in the direction of use. The main use of cold-rolled non-oriented silicon steel sheet is for generator manufacturing, so it is also called cold-rolled motor silicon steel. . The main purpose of cold-rolled oriented silicon steel strip is for transformer manufacturing, so it is also called cold-rolled transformer silicon steel.
Non-oriented silicon steel sheet
Silicon steel is commonly known as silicon steel sheet or silicon steel sheet. It is an indispensable low-carbon ferrosilicon soft magnetic alloy in the power, electronics and military industries. It is the metal functional material with the largest output, and its output accounts for about 1% of the world's steel output. It is a ferrosilicon alloy with a silicon content of 0.8%-4.8%, which is hot and cold rolled into a silicon steel sheet with a thickness of less than 1mm. The addition of silicon can increase the resistivity and maximum permeability of iron, reduce coercivity, core loss (iron loss) and magnetic aging. It is mainly used as the core of various motors, generators and transformers.
Classification
A, silicon steel sheets can be divided into low silicon and high silicon according to their silicon content. Low silicon wafer contains silicon less than 2.8%, it has certain mechanical strength, it is mainly used to make motors, commonly known as motor silicon steel sheet; high silicon wafer has silicon content of 2.8%-4.8%, it has good magnetic properties, but is relatively brittle, and is mainly used Used in the manufacture of transformer cores, commonly known as transformer silicon steel sheets. There is no strict boundary between the two in actual use, and high-silicon wafers are often used to manufacture large motors.
B. According to the production process, it can be divided into two types: hot rolling and cold rolling. Cold rolling can be divided into two types: non-oriented and oriented. Cold-rolled sheets have uniform thickness, good surface quality and high magnetic properties. Therefore, with the development of industry, hot-rolled sheets have a tendency to be replaced by cold-rolled sheets. "Replace heat with cold").
Performance indicators
A, low iron loss. The most important indicator of quality, all countries in the world classify grades by iron loss value. The lower the iron loss, the higher the grade and the higher the quality.
B. High magnetic induction intensity. In the same magnetic field, a silicon steel sheet with higher magnetic induction can be obtained. The motor or transformer core made of it has a small volume and weight, and relatively speaking, it can save silicon steel sheet, copper wire and insulating materials.
C, high stacking factor. The surface of the silicon steel sheet is smooth, flat and uniform in thickness, and the stacking factor of the manufactured iron core is improved.
D. Good film development. This is even more important for the manufacture of small and micro motor cores.
E. The surface has good adhesion and weldability to the insulating film, which can prevent corrosion and improve the punching property.
F, magnetic aging phenomenon is small
G, silicon steel sheet must be delivered after annealing and pickling.