Oxide inclusion control method for producing ultra-low-carbon steel by using LD-RH process

A technology of ultra-low carbon steel and control method, which is applied to the improvement of process efficiency and the manufacture of converters, etc. It can solve the problems such as difficult to determine the process effect, achieve remarkable cleaning effect, improve product quality, reduce the number of oxide inclusions and finished products The effect of oxygen content

Active Publication Date: 2019-04-02
BAOSHAN IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The process effect emphasized in this patent is measured by the loss of acid-soluble aluminum in the steel, but the slag already contains metal Al, so its process effect is difficult to determine

Method used

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  • Oxide inclusion control method for producing ultra-low-carbon steel by using LD-RH process

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030]Converter blowing is completed, [C]=280ppm, [O]=650ppm, slag is blocked and tapped to ensure ladle slag thickness ≤ 50mm, lime 2.2-2.5kg / t steel is added at the beginning of tapping, and aluminum slag is added at the end of 0.8-1.0kg / t steel, ladle top slag composition before vacuum treatment (FeO wt%)+(MnO wt%)=6.7%, [(CaO wt%)+(MgO wt%)] / (Al 2 o 3 wt%)=1.72, and the slag thickness is 130mm.

[0031] In the RH furnace, vacuum decarburization treatment is carried out so that the carbon in the molten steel is below the required value of the finished product. After the vacuum decarburization is completed, Al is added to deoxidize the molten steel, followed by adding a refining agent of 0.7kg / t steel from the high-level silo. The composition of the refining agent is shown in Table 1. The molten steel is purely circulated for 2-7 minutes, the molten steel is alloyed, and the composition of the molten steel is adjusted to the specification range. The molten steel is purel...

Embodiment 2

[0034] Converter blowing is completed, [C] = 340ppm, [O] = 580ppm, slag blocking and tapping, to ensure that the ladle slag thickness is ≤ 50mm, add lime 2.3-2.7kg / t steel at the beginning of tapping, and add aluminum slag 0.9-1.2kg at the end / t steel, ladle top slag composition (FeOwt%)+(MnOwt%)=6.5% before vacuum treatment, [(CaO wt%)+(MgOwt%)] / (Al 2 o 3 wt%)=1.77, and the slag thickness is 132mm.

[0035] In the RH furnace, vacuum decarburization treatment is carried out so that the carbon in the molten steel is below the required value of the finished product. After the vacuum decarburization is completed, Al is added to deoxidize the molten steel, followed by adding a refining agent of 1.04kg / t steel from the high-level silo. The composition of the refining agent is shown in Table 1. The molten steel is purely circulated for 2-8 minutes, the molten steel is alloyed, and the composition of the molten steel is adjusted to the specification range. The molten steel purely...

Embodiment 3

[0038] Converter blowing is completed, [C] = 270ppm, [O] = 645ppm, slag is blocked and tapped to ensure ladle slag thickness ≤ 50mm, lime 2.5-3.4kg / t steel is added at the beginning of tapping, and aluminum slag is added at the end 0.7-0.9kg / t steel, ladle top slag composition (FeOwt%)+(MnOwt%)=6.2% before vacuum treatment, [(CaO wt%)+(MgOwt%)] / (Al 2 o 3 wt%)=1.82, and the slag thickness is 133mm.

[0039] In the RH furnace, vacuum decarburization treatment is carried out so that the carbon in the molten steel is below the required value of the finished product. After the vacuum decarburization is completed, Al is added to deoxidize the molten steel, followed by adding a refining agent of 0.48kg / t steel from the high-level silo. The composition of the refining agent is shown in Table 1. The molten steel is purely circulated for 3-7 minutes, the molten steel is alloyed, and the composition of the molten steel is adjusted to the specification range. The molten steel is purel...

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Abstract

The invention discloses an oxide inclusion control method for producing ultra-low-carbon steel by using an LD-RH process. The method comprises the following steps that 2.0-3.5 kg of lime is added intoper ton of steel at the early stage of steel tapping of an LD converter, and 0.3-2 kg of Al modifiers are added into per ton of steel at the end of steel tapping; then the mixture enters an RH furnace to be subjected to vacuum treatment and decarbonization; after decarbonization is finished, deoxidizing is carried out, and 0.3-2.0 kg of refining agents are added int per ton of steel, wherein therefining agent comprises the following components of, by weight, 50-60wt% of CaO, 30-40wt% of Al2O3, 2-6wt% of MgO, less than or equal to 3wt% of SiO2, less than 0.08wt% of TiO2, less than or equal to1wt% of FeO and less than or equal to 0.5wt% of H2O; and alloying is carried out, wherein molten steel is circulated for 3-12 minutes, and then the vacuum refining process is finished. According to the method, the number of oxide inclusions in the casting blank and the oxygen content of a finished product are greatly reduced, the cold rolling blocking rate is reduced, and the quality of the ultra-low carbon steel product is remarkably improved.

Description

technical field [0001] The invention belongs to the steelmaking process technology of metallurgical science, and in particular relates to an oxide inclusion control method for producing ultra-low carbon steel by LD-RH process. Background technique [0002] With the advancement of technology, users have higher and higher demands on steel quality. For ultra-low carbon steel, there has been demand for cold-rolled finished plates as thin as 0.05mm. When ultra-low carbon steel is smelted, the oxygen (free oxygen and combined oxygen) added by converter smelting is the most important oxygen source in the whole smelting process, and then during the tapping process, molten steel and steel slag containing a large amount of oxygen enter the ladle. Oxygen in molten steel is not only used for vacuum cycle refining decarburization, but also forms oxide inclusions in the deoxidation process, which is harmful to the quality of steel. [0003] From the point of view of smelting, it is nece...

Claims

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Application Information

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IPC IPC(8): C22C33/04C21C5/35C21C7/06C21C7/10C21C7/068C22C38/04C22C38/06C22C38/02C22C38/14
CPCC21C5/35C21C7/0006C21C7/06C21C7/068C21C7/10C22C33/04C22C38/02C22C38/04C22C38/06C22C38/14Y02P10/20
Inventor 胡汉涛马志刚王俊凯
Owner BAOSHAN IRON & STEEL CO LTD
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