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Method for producing high-grade non-oriented silicon steel by thin slab continuous casting and rolling process

  • Time of issue:2018-09-26 02:31

(Summary description)How to use the thin slab continuous casting and rolling process to produce high-grade non-oriented silicon steel so as to give full play to the advantages of the thin slab continuous casting and rolling process is a technical problem that urgently needs to be solved in the prior art.

Method for producing high-grade non-oriented silicon steel by thin slab continuous casting and rolling process

(Summary description)How to use the thin slab continuous casting and rolling process to produce high-grade non-oriented silicon steel so as to give full play to the advantages of the thin slab continuous casting and rolling process is a technical problem that urgently needs to be solved in the prior art.

  • Categories:Industry News
  • Author:
  • Origin:Electrical steel pilot
  • Time of issue:2018-09-26 02:31
  • Views:

  How to use the thin slab continuous casting and rolling process to produce high-grade non-oriented silicon steel so as to give full play to the advantages of the thin slab continuous casting and rolling process is a technical problem that urgently needs to be solved in the prior art.

 

Application Number
CN201810310721.0
Application date
2018.04.09
Public (Announcement) Number
CN108374130A
Public (Announcement) Day
2018.08.07
 
  The non-oriented silicon steel of the present invention has the following chemical composition mass percentages:
  Si: 2.5~3.5%, Al: 0.10~1.5%, Mn: 0.10~1.5%, [S+O+C+N+Ti]≤80ppm, rare earth elements (La and/or Ce and/or Nd): 0.001 ~0.01%, the balance is Fe and other impurity elements.
The method for producing non-oriented silicon steel in the thin slab continuous casting and rolling process of the present invention includes the following steps: Step A: Smelting; Step B: Continuous Casting; Step C: Heating; Step D: Hot Continuous Rolling; Step E: Pickling; Step F: cold rolling; Step G: recrystallization annealing.
   As a further improvement of the present invention, in the smelting process of step A, the converter smelting is carried out first, and then the RH refining treatment is carried out. After the treatment, the mass percentage of the chemical composition of the molten steel at the end point is:
Si: 2.5~3.5%, Al: 0.10~1.5%, Mn: 0.10~1.5%, [S+O+C+N+Ti]≤80ppm, rare earth elements (La and/or Ce and/or Nd): 0.001 ~0.01%, the balance is Fe and other impurity elements;
   The rare earth element is added within 1 to 2 minutes after the RH refining and alloying is finished, and the rare earth element is added after stirring, and the stirring time is ≥3 minutes.
"As a further improvement of the present invention, in the continuous casting process of step B, the drawing speed is controlled to be 2.8-4.6 m/min, and the continuous casting obtains a slab with a thickness of 30-70 mm.
   As a further improvement of the present invention, in the heating process of step C, the casting slab is sent to a tunnel furnace for heating, the casting slab entering the furnace temperature is ﹥800°C, the heating temperature is 950-1150°C, and the soaking time is less than 30 minutes.
As a further improvement of the present invention, in the process of step D hot tandem rolling, 7-stand hot tandem rolling is performed, the start-rolling temperature is controlled at 950-1100°C, the final rolling temperature is controlled at 900-920°C, and the coiling temperature is controlled at 600-700°C. , Control the target thickness of hot-rolled sheet from 0.8 to 1.0mm.
"As a further improvement of the present invention, in the cold rolling process of step F, cold rolling is performed to a thickness of 0.5 mm.
   As a further improvement of the present invention, in the recrystallization annealing process of step G, the annealing temperature is controlled to be 1000 to 1200° C., and the holding time is controlled to be 1 to 3 minutes.
As a further improvement of the present invention, in the continuous casting process of step B, the overheating degree of the tundish is controlled to be less than or equal to 0°C to ensure that the equiaxed crystal ratio is greater than or equal to 80%; Step F cold rolling process control reduction ratio≤50%.
   As a further improvement of the present invention, the step F cold rolling process adopts a single-stand reversible cold rolling mill or a cold tandem rolling mill; the step G recrystallization annealing process adopts a pure hydrogen atmosphere.
 
  Beneficial effect
   Compared with the prior art, the technical solution provided by the present invention has the following remarkable effects:
  

  (1) The existing thin slab continuous casting and rolling production process for low- and medium-grade non-oriented silicon steel is basically mature, but for high-grade non-oriented silicon steel, especially when the silicon content is greater than 2.5%, there are obvious product defects. In view of the above problems In the method for producing non-oriented silicon steel in the thin slab continuous casting and rolling process of the present invention, the process parameters from step A to step G are matched with each other, and the qualified high-grade non-oriented silicon steel is produced by the thin slab continuous casting and rolling process, thereby Give full play to the advantages of the thin slab continuous casting and rolling process.

  (2) The method for producing non-oriented silicon steel in the thin slab continuous casting and rolling process of the present invention, in the thin slab continuous casting and rolling process, by reasonably setting the composition and process, it is produced without electromagnetic stirring and impermanence. The high-grade high-efficiency non-oriented silicon steel with silicon content> 2.5% has high magnetic induction and low iron loss in the final product. It solves the corrugated defects that are easy to occur in the production of high-grade non-oriented silicon steel by the existing thin slab continuous casting and rolling process. Its main technology The characteristics are reflected in: molten steel [S+O+C+N+Ti] is required to be less than or equal to 80ppm, ultra-pure molten steel; adding rare earth elements, one is to deeply purify molten steel, reduce inclusions and improve magnetic properties, and the other is to use rare earth sulfides As a nucleation point, it refines the columnar crystals of the cast slab and eliminates corrugation; the casting process adopts negative superheat, so that the equiaxed crystal ratio is greater than 80%, and the corrugation is eliminated; the reduction rate of the last pass of the hot continuous rolling process is controlled to be greater than 50%, and the low temperature Large reduction reduces the band structure of the core of the hot-rolled sheet, improves the hot-rolled structure, and eliminates corrugation; optimizes the thickness of the hot-rolled sheet, controls the reduction rate in the cold rolling process ≤50%, and reduces the (111) texture in the medium reduction rate. , Increase (100) texture and improve magnetic properties.

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