A control method for oxide inclusions in ultra-low carbon steel produced by ld-rh process

A technology of ultra-low carbon steel and control method, which can be applied in the direction of improving process efficiency, manufacturing converters, etc., and can solve problems such as difficulty in determining the process effect.

Active Publication Date: 2021-06-15
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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  • A control method for oxide inclusions in ultra-low carbon steel produced by ld-rh process

Examples

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

A method for controlling oxide inclusions in ultra-low carbon steel produced by LD-RH process, which includes adding lime 2.0-3.5kg / t steel in the early tapping stage of LD converter, and adding 0.5-1.2kg / t Al-based modifier at the end of tapping Steel; then enter the RH furnace for vacuum decarburization; decarburization is completed, deoxidation, adding refining agent 0.3-2kg / t steel, the composition of the refining agent is: CaO: 50-60wt%, Al 2 o 3 : 30~40wt%, MgO: 2~6wt%, SiO 2 ≤3wt%, TiO 2 <0.08wt%, FeO≤1wt%, H 2 O≤0.5wt%; alloying; circulation of molten steel for 3‑12 minutes, and the vacuum refining process ends. The method greatly reduces the amount of oxide inclusions in the slab and the oxygen content of the finished product, reduces the blocking rate of cold rolling, and significantly improves the quality of ultra-low carbon steel products.

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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Patent Type & Authority Patents(China)
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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