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Several matters needing attention on silicon steel smelting, do a good job with half the effort

  • Time of issue:2020-11-27 17:59

(Summary description)Silicon steel is a kind of soft magnetic material. It is mainly used to manufacture iron cores of motors and transformers. The performance requirements of silicon steel mainly include iron loss, magnetic induction, magnetic anisotropy, magnetic aging, and brittleness. The smelting process of silicon steel is more than other The steel grade is more complex, requiring precise process technology in all links such as refining, converter, RH vacuum, and continuous casting.

Several matters needing attention on silicon steel smelting, do a good job with half the effort

(Summary description)Silicon steel is a kind of soft magnetic material. It is mainly used to manufacture iron cores of motors and transformers. The performance requirements of silicon steel mainly include iron loss, magnetic induction, magnetic anisotropy, magnetic aging, and brittleness. The smelting process of silicon steel is more than other The steel grade is more complex, requiring precise process technology in all links such as refining, converter, RH vacuum, and continuous casting.

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  • Time of issue:2020-11-27 17:59
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  Silicon steel is a kind of soft magnetic material, which is mainly used to manufacture iron cores of motors and transformers. The performance requirements of silicon steel mainly include iron loss, magnetic induction, magnetic anisotropy, magnetic aging, brittleness, etc.; the smelting process of silicon steel is more than other The steel grade is more complex, requiring precise process technology in all links such as refining, converter, RH vacuum, and continuous casting.

  Silicon steel is a kind of soft magnetic material. The silicon content is in the range of 1.0% to 4.5%. It is mainly used to manufacture iron cores in motors and transformers, ballasts in fluorescent lamps, magnetic switches and relays, magnetic shields and magnets in high-energy accelerators. Wait. The performance of silicon steel has the following requirements:

  (1) Low iron loss. Because high iron loss will increase power loss, the main effect of adding silicon to steel is to reduce iron loss; reducing sulfur content is beneficial to reducing iron loss; appropriately increasing phosphorus content in steel is beneficial to reducing iron loss.

  (2) High magnetic induction intensity. The high magnetic induction can reduce the core excitation current (no-load current), reduce the copper loss and core loss caused by the wire resistance, and save energy.

  (3) Requirements for magnetic anisotropy. The motor works in the running state and requires the silicon steel to be magnetically isotropic and is made of non-oriented silicon steel; the transformer works in a static state and is made of cold-rolled oriented silicon steel.

  (4) The magnetic aging is small. The phenomenon that the magnetism of the iron core changes with the use time is magnetic aging. Magnetic aging is mainly caused by fine carbides and nitrides precipitated by supersaturated carbon and nitrogen in steel. Therefore, the carbon content in high-quality non-oriented silicon steel should be less than 0.0035%, and the nitrogen content should be less than 0.005%.

  (5) The brittleness is small. The silicon steel sheet must be stamped and formed when the iron core is made, and the punching performance is better; if the steel is brittle, it will reduce the yield and affect the life of the die. Sulfur is not only harmful to magnetism, but also makes steel hot and brittle, which should be reduced as much as possible.

  In addition, the surface of the silicon steel sheet should be smooth and flat, the thickness uniformity should be small, and the insulating film should be good.

  The smelting process must adapt to the requirements of different grades of silicon steel, and the non-oriented silicon steel requires ultra-low carbon, low sulfur and low nitrogen content. In general, the main points of silicon steel smelting are as follows:

 

  A. Concentrate

  (1) Use low-manganese molten iron for smelting, requiring wMn<0.35%, and using low-manganese scrap steel, requiring wMn<0.35%. High manganese content in the steel will deteriorate the magnetic properties of the silicon steel sheet;

  (2) Hot metal pretreatment desulfurization, molten iron entering the furnace w[s]<0.005%:

  (3) Use high-grade ferrosilicon alloy (low carbon and manganese content);

  (4) The auxiliary raw materials are stable in composition and less impurity.

  B, converter blowing

  top-bottom composite blowing process, decarburization, demanganization, temperature control, the end point carbon is controlled at 0.04%.

  C, ladle alloying and argon blowing at the bottom

  The alloy should be added uniformly, and the addition should be completed before the tapping amount reaches 70%.

  D, RH vacuum treatment

  Fine-tune the composition of molten steel to meet the specified requirements and control the end temperature.

  E, continuous casting process

  (1) Due to the high silicon content of molten steel and poor thermal conductivity, slow pouring is used, and the secondary cooling uses a weak cooling system.

  (2) The whole process of pouring is protected, and the mold uses special protective slag.

  (3) Electromagnetic stirring is used in the second cold zone to increase the ratio of equiaxed crystals and eliminate corrugated defects on the surface of the silicon steel sheet.

  (4) The continuous casting billet is delivered hot, and the heat preservation trolley is used to prevent cracks.

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