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CN-122007355-A - Method for reducing silicon dioxide on surface of crystallization roller for thin-strip continuous casting non-oriented silicon steel

CN122007355ACN 122007355 ACN122007355 ACN 122007355ACN-122007355-A

Abstract

The invention belongs to the technical field of metallurgical engineering, and particularly relates to a method for reducing silicon dioxide on the surface of a crystallization roller used for thin strip continuous casting non-oriented silicon steel. The invention reduces the wetting angle between molten steel and a crystallization roller and simultaneously reduces the content of silicon dioxide in a deposited film on the surface of the crystallization roller as much as possible under the synergistic effect of the preparation process by optimizing the rare earth types, the addition amount and the proportion. The method provides a key technical support for the high-efficiency and stable thin strip continuous casting production of the high-silicon non-oriented silicon steel. Through the cooperative regulation and control of the invention, the interfacial heat transfer of the non-oriented silicon steel is enhanced, and the surface quality is improved. The method effectively solves the problems of poor heat transfer performance and poor castable property of the high-silicon non-oriented silicon steel, and provides a brand new way for realizing stable casting and obtaining excellent surface quality.

Inventors

  • WANG WANLIN
  • YI SHUAN
  • ZHU CHENYANG
  • ZENG JIE

Assignees

  • 中南大学

Dates

Publication Date
20260512
Application Date
20260409

Claims (8)

  1. 1. A method for reducing silicon dioxide on the surface of a crystallization roller used for thin strip continuous casting non-oriented silicon steel is characterized by comprising the following steps: S1, adjusting and controlling the chemical components of molten steel, wherein the chemical components comprise, by mass, less than or equal to 0.003% of C, 2.5-3.5% of Si, 0.27% of Mn, less than or equal to 0.004% of P, less than or equal to 0.003% of S, less than or equal to 0.003% of N, 0.015-0.15% of mixed rare earth, and the balance of Fe and unavoidable impurities; S2, injecting the molten steel obtained in the step S1 into double-roller thin-belt continuous casting equipment, and enabling the molten steel to contact with a rotating crystallization roller to form a molten pool, casting under the condition of sub-rapid solidification with the cooling speed of 10 2 ~ 10 4 ℃ per second to obtain a casting belt, controlling the casting temperature to be 50-95 ℃ of superheat degree, taking Ar gas as protective atmosphere in the whole process and water as cooling medium, wherein the casting roller is made of copper, the roller gap is 1.8-2.0 mm, and the casting speed is 0.6-0.7 m/S; s3, forming a layer of natural deposition film on the surface of the crystallization roller in the molten steel cooling process through the step S2.
  2. 2. The method for reducing surface silicon dioxide of a crystallization roller for thin strip continuous casting non-oriented silicon steel as claimed in claim 1, wherein in the step S1, the misch metal is at least 2 kinds selected from La, ce, Y, sc. La and Ce are preferred.
  3. 3. The method for reducing the surface silicon dioxide of a crystallization roller for thin strip continuous casting non-oriented silicon steel according to claim 1, which is characterized by comprising the following steps: S1, adjusting and controlling chemical components of molten steel, wherein the chemical components comprise, by mass, less than or equal to 0.003% of C, 2.5-2.8% of Si, 0.27% of Mn, less than or equal to 0.004% of P, less than or equal to 0.003% of S, less than or equal to 0.003% of N, 0.015-0.02% of mixed rare earth, and the balance of Fe and unavoidable impurities, and the mixed rare earth consists of La and Ce according to a molar ratio of 1:2-2.3; S2, injecting the molten steel obtained in the step S1 into double-roller thin-belt continuous casting equipment, enabling the molten steel to contact with a rotating crystallization roller to form a molten pool, casting under the condition of sub-rapid solidification with the cooling speed of 10 2 ~ 10 4 ℃ per second to obtain a casting belt, controlling the casting temperature to be 50-55 ℃ of superheat degree, taking Ar gas as protective atmosphere in the whole process, taking water as cooling medium, enabling the casting roller to be made of copper, enabling the roller gap to be 1.8-2.0 mm, and enabling the casting speed to be 0.6-0.7 m/S.
  4. 4. A method for reducing surface silicon dioxide of a crystallization roller for thin strip continuous casting non-oriented silicon steel according to claim 3, wherein the content of SiO 2 in a deposited film on the surface of the crystallization roller is reduced to 28.9-29 wt.%.
  5. 5. The method for reducing the surface silica of a crystallization roll used for thin strip continuous casting non-oriented silicon steel according to claim 1, which is characterized in that: S1, smelting non-oriented silicon steel by adopting a vacuum induction furnace, wherein the mass percentage of chemical components of molten steel is controlled to be less than or equal to 0.003 percent, 3.2-3.5 percent, 0.27 percent, less than or equal to 0.004 percent, less than or equal to 0.003 percent, 0.015-0.02 percent and the balance of Fe and unavoidable impurities, and the mixed rare earth consists of La and Ce according to the molar ratio of 1:1-1.2; S2, heating the molten steel to a superheat degree of 85-90 ℃, injecting the molten steel into double-roller thin strip continuous casting equipment for casting, wherein the casting rollers are made of copper, the roller gap is 1.8-2.0 mm, and the casting speed is 0.7 m/S.
  6. 6. The method for reducing surface silicon dioxide of a crystallization roller for thin strip continuous casting non-oriented silicon steel as claimed in claim 5, wherein the content of SiO 2 in a deposited film of the crystallization roller is reduced to 29.2-29.35 wt.%.
  7. 7. The method for reducing surface silicon dioxide of a crystallization roller for thin strip continuous casting non-oriented silicon steel as claimed in claim 6, wherein the misch metal consists of La and Ce according to a molar ratio of 1:1.
  8. 8. The method for reducing surface silicon dioxide of a crystallization roller for thin strip continuous casting non-oriented silicon steel as claimed in claim 4 or 6, wherein the surface deposited film of the crystallization roller is a natural deposited film after 7 times of repeated experiments.

Description

Method for reducing silicon dioxide on surface of crystallization roller for thin-strip continuous casting non-oriented silicon steel Technical Field The invention belongs to the technical field of metallurgical engineering, and particularly relates to a method for reducing silicon dioxide on the surface of a crystallization roller used for thin strip continuous casting non-oriented silicon steel. Background The magnetic property of the non-oriented silicon steel serving as a core soft magnetic material of electric equipment such as motors, generators and the like directly determines the energy efficiency level of the equipment. Research shows that the improvement of the silicon content is the most effective technical approach for reducing the iron loss and improving the magnetic induction performance, and particularly under the high-frequency working condition, the eddy current loss can be obviously restrained by the high resistivity caused by the high silicon. Therefore, the non-oriented silicon steel is necessarily developed to the high-silicidation direction in the high-end application fields of high-efficiency motors, new energy automobile driving motors and the like. However, the increase in silicon content, while optimizing magnetic properties, also presents a significant challenge to the thin strip casting process. When the silicon content goes into a high silicon system (> 3.0%), the physicochemical properties of silicon steel will also change significantly. Firstly, the viscosity of molten steel is increased to greatly reduce wettability, secondly, the heat conductivity coefficient of silicon steel is obviously reduced, the solidification rate is slowed down to restrict the improvement of pulling speed and the production efficiency, furthermore, the high silicon steel lacks austenite phase transformation in the solidification process, volume shrinkage compensation cannot be formed, and the air gap formation tendency is aggravated. The factors are mutually overlapped, so that the silicon dioxide content in the deposited film on the surface of the crystallization roller in the double-roller thin-belt continuous casting process of the high-silicon non-oriented silicon steel is too high, the interfacial heat transfer is blocked, the solidification uniformity is poor, the surface quality of the casting belt is deteriorated, and stable and efficient production is difficult to realize. In contrast, although the medium silicon non-oriented silicon steel has certain castability, the magnetic property of the medium silicon non-oriented silicon steel is difficult to meet the high-end application requirement. If the interfacial behavior of the molten steel can be further improved, the surface quality of the molten steel can be optimized. Under a high-silicon system, due to the problems of poor wettability, slow heat transfer, multiple air gaps and the like, stable casting of molten steel is difficult, production efficiency is limited, surface quality control is difficult, and the method becomes a technical bottleneck for restricting the industrial application of high-silicon non-oriented silicon steel thin strip continuous casting. In view of the above interface problem, studies have shown that the naturally formed oxide deposition film (mainly composed of oxides of O, fe, si, mn and other elements) on the surface of the crystallization roller can affect the interface heat transfer behavior to some extent. The deposited film with proper thickness can fill up microscopic air gaps, improve interface contact state and has certain lubrication function. However, the composition, thickness and distribution of the deposited film are doubly influenced by the molten steel composition and technological parameters, and the regulation and control difficulty is high. Rare earth elements have obvious potential in regulating and controlling the interface behavior of metal melt due to the unique electronic layer structure and surface activity characteristics. The atomic radius is large, the electronegativity is low, and the interfacial energy state is easy to be absorbed and changed at the interface, so that the surface tension and the interfacial tension of molten steel are effectively reduced. It has been widely used in the preparation process of non-oriented silicon steel. For example, patent CN120818740A, CN117904394A, CN119876733a relates to the introduction of rare earth into non-oriented silicon steel, but so far, there is a few related records of rare earth species ratio selection matching with thin strip continuous casting process parameters to reduce the silica on the surface of the used crystallization roller. Disclosure of Invention Aiming at the defects of the prior art, the invention firstly proposes to reduce the silicon dioxide on the surface of the used crystallization roller by utilizing the rare earth type proportion to select and match with the thin strip continuous casting process parameters. According t