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CN-119634690-B - Thin slab continuous casting method

CN119634690BCN 119634690 BCN119634690 BCN 119634690BCN-119634690-B

Abstract

The invention provides a thin slab continuous casting method, and belongs to the field of continuous casting. The method comprises the steps of casting molten steel, determining the types of the protective slag according to the drawing speed of a casting machine in the casting process, wherein the protective slag is first protective slag when the drawing speed of the casting machine is less than 4.5m/min, the viscosity of the first protective slag at 1300 ℃ is 0.10 Pa.s-0.20 Pa.s, the protective slag is second protective slag when the drawing speed of the casting machine is more than or equal to 4.5m/min, and the viscosity of the second protective slag at 1300 ℃ is 0.04 Pa.s-0.08 Pa.s. Through two-stage addition of the covering slag, the lubricating and heat transfer effects at low pulling speed can be met, and the consumption, heat transfer and liquid slag layer thickness of the covering slag at high pulling speed can be met. Therefore, the lubricating performance and the heat transfer performance of the casting powder at different pulling speeds can be effectively balanced, and the surface quality of a casting blank is further improved.

Inventors

  • LUO YANZHAO
  • XU HAIWEI
  • LIU JINGANG
  • JI CHENXI
  • LIU YANQIANG
  • JIA LIUBING
  • ZHANG CONGCONG
  • WANG SHENGDONG
  • WANG HAO
  • ZHOU HAICHEN
  • YANG FEIFEI
  • WANG BAOSHENG
  • YANG CHUNZHENG

Assignees

  • 首钢集团有限公司

Dates

Publication Date
20260512
Application Date
20241211

Claims (10)

  1. 1. A method of continuous sheet bar casting, the method comprising: Casting the molten steel, and adopting two-section low-carbon steel covering slag according to the difference of pulling speed during casting in the casting process; when the pulling speed of the casting machine is less than 4.5m/min, the casting powder is first casting powder, and the viscosity of the first casting powder at 1300 ℃ is 0.10 Pa.s-0.20 Pa.s; When the pulling speed of the casting machine is more than or equal to 4.5m/min, the mold flux is second mold flux, and the viscosity of the second mold flux at 1300 ℃ is 0.04 Pa.s-0.08 Pa.s; the first casting powder is added in the process that the pulling speed of the casting machine is increased from 0 to 0.8 m/min; When the pulling speed reaches 0.8m/min, the pulling speed is directly increased to 3.5m/min at the increasing speed of 1.5m/min 2 .
  2. 2. The method according to claim 1, wherein the chemical composition of the first mold flux includes ：CaO：25.0%~35.0%,SiO 2 ：24.0%~28.0%,Al 2 O 3 ：4.0%~8.0%,MgO：5.0%~9.0%,MnO：1.0%~3.0%,NaO 2 +K 2 O：5.0%~9.0%,LiO 2 ＜5.0%,C：4.0%~6.0%, balance unavoidable impurities in mass fraction.
  3. 3. The method of claim 2, wherein the first protective slag has a melting point of 1000 ℃ to 1100 ℃.
  4. 4. The method according to claim 3, wherein the basicity of the first mold flux is 1.05 to 1.15.
  5. 5. The method according to claim 2, wherein the chemical composition of the first mold flux is ：CaO：30.0%,SiO 2 ：25.5%,Al 2 O 3 ：5.8%,MgO：6.8%,MnO：1.63%,NaO 2 +K 2 O：7.1%,LiO 2 ：0.66%,C：5.65%, and the balance is unavoidable impurities, the melting point of the first mold flux is 1038 ℃, the viscosity of the first mold flux at 1300 ℃ is 0.10 Pa-s, and the basicity of the first mold flux is 1.10.
  6. 6. The method according to claim 1, wherein the chemical composition of the second mold flux includes ：CaO：30.0%~35.0%,SiO 2 ：25.0%~30.0%,Al 2 O 3 ：4.0%~8.0%,MgO：6.0%~8.0%,MnO：0.05%~0.20%,NaO 2 +K 2 O：6.0%~10.0%,LiO 2 ＜5.0%,C：4.0%~6.0%, the balance unavoidable impurities in mass fraction.
  7. 7. The method according to claim 6, wherein the second mold flux has a melting point of 950 ℃ to 1050 ℃.
  8. 8. The method according to claim 7, wherein the second mold flux has an alkalinity of 1.25 to 1.35.
  9. 9. The method according to claim 6, wherein the chemical composition of the second mold flux is ：CaO：32.9%,SiO 2 ：27.2%,Al 2 O 3 ：6.4%,MgO：5.9%,MnO：0.10%,NaO 2 +K 2 O：8.2%,LiO 2 ：0.88%,C：5.23%;, the melting point of the second mold flux is 1005 ℃, the viscosity of the second mold flux at 1300 ℃ is 0.06 Pa-s, and the basicity of the second mold flux is 1.29, in mass fraction.
  10. 10. The method according to claim 1, wherein the molten steel is molten steel for low carbon steel.

Description

Thin slab continuous casting method Technical Field The application relates to the technical field of continuous casting, in particular to a thin slab continuous casting method. Background Shoudu Iron and Steel Co sheet bar continuous casting and rolling equipment is a world-first third-generation sheet bar continuous casting and rolling production line based on the existing second-generation TSCR technology, and integrates the forefront technology of the current continuous casting and rolling. Has a plurality of production modes of single blank production, semi-endless production and full endless production. The product line adopts endless rolling, mainly uses high-quality, high-strength and ultra-thin specification products, realizes the production of high-end thin specification hot rolled products by replacing cold with hot, and simultaneously can produce products with high surface quality, good plate shape and uniform and stable isotropic properties. Mainly comprises three major categories of thin-specification hot rolled coils, hot rolled pickled plates and hot-base galvanized plates. The total endless rolling specification is 0.8-4.0mm, and the varieties comprise automobile structural steel, high-strength steel, weather-resistant steel, acid-washed base plate, bidirectional steel, high-reaming steel, medium manganese steel, martensitic steel and cold rolling base stock. The casting machine of the equipment is of a straight arc type, the arc radius is 5.5m, the ladle and the medium inclusion are 200t and 70t respectively, the crystallizer is of a long funnel type, the casting blank specification range is (900-1600) x (110-123) mm, and the metallurgical length is 26.567m. Adopts a dual-mode fusion pressing technology, namely the fan-shaped 0-1 section liquid core pressing and the solidification tail end pressing lightly, thereby realizing the aims of thinning and improving the internal quality. However, as the thickness of the section of the crystallizer of the continuous casting and rolling production line of the sheet billet is small, the fluctuation of the liquid level is aggravated along with the increase of the pulling speed, and the problems of the adhesive alarm of the crystallizer, the casting blank with slag inclusion defects, the surface crack of the casting blank and the like are extremely easily caused. Disclosure of Invention The application provides a thin slab continuous casting method, which aims to solve the technical problem of how to improve the surface quality of a casting blank. The application provides a thin slab continuous casting method, which comprises the following steps: Casting the molten steel, and determining the kind of the covering slag according to the pulling speed of a casting machine in the casting process; when the pulling speed of the casting machine is less than 4.5m/min, the casting powder is first casting powder, and the viscosity of the first casting powder at 1300 ℃ is 0.10 Pa.s-0.20 Pa.s; when the pulling speed of the casting machine is more than or equal to 4.5m/min, the mold flux is second mold flux, and the viscosity of the second mold flux at 1300 ℃ is 0.04 Pa.s-0.08 Pa.s. Optionally, the chemical components of the first mold flux include ：CaO：25.0％～35.0％,SiO2：24.0％～28.0％,Al2O3：4.0％～8.0％,MgO：5.0％～9.0％,MnO：1.0％～3.0％,NaO2+K2O：5.0％～9.0％,LiO2＜5.0％,C：4.0％～6.0％, balance unavoidable impurities in mass fraction. Optionally, the melting point of the first protection slag is 1000 ℃ to 1100 ℃. Optionally, the alkalinity of the first mold flux is 1.05-1.15. Optionally, the chemical composition of the first protective slag is ：CaO：30.0％,SiO2：25.5％,Al2O3：5.8％,MgO：6.8％,MnO：1.63％,NaO2+K2O：7.1％,LiO2：0.66％,C：5.65％, percent by mass, the balance is unavoidable impurities, the melting point of the first protective slag is 1038 ℃, the viscosity of the first protective slag at 1300 ℃ is 0.10 Pa.s, and the alkalinity of the first protective slag is 1.10. Optionally, the chemical components of the second mold flux include ：CaO：30.0％～35.0％,SiO2：25.0％～30.0％,Al2O3：4.0％～8.0％,MgO：6.0％～8.0％,MnO：0.05％～0.20％,NaO2+K2O：6.0％～10.0％,LiO2＜5.0％,C：4.0％～6.0％, balance unavoidable impurities in mass fraction. Optionally, the melting point of the second mold flux is 950 ℃ to 1050 ℃. Optionally, the alkalinity of the second mold flux is 1.25-1.35. Optionally, the chemical composition of the second mold flux is ：CaO：32.9％,SiO2：27.2％,Al2O3：6.4％,MgO：5.9％,MnO：0.10％,NaO2+K2O：8.2％,LiO2：0.88％,C：5.23％;, the melting point of the second mold flux is 1005 ℃, the viscosity of the second mold flux at 1300 ℃ is 0.06pa·s, and the alkalinity of the second mold flux is 1.29. Optionally, the molten steel is molten steel for low-carbon steel. Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages: The application provides a thin slab continuous casting method, which comprises the steps of casting molten steel, determining the types of casting powder