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Steel melting method for reducing nitrogen content in steel by converter tapping feeble deoxidization

A nitrogen content, converter technology, applied in the field of iron and steel metallurgy, can solve the problems of reducing nitrogen absorption, uncontrollable nitrogen increase, reducing nitrogen content, etc., and achieves obvious effects, good industrial application prospects, and lower steelmaking costs.

Inactive Publication Date: 2009-07-01
ANYANG IRON & STEEL GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Practice has proved that the amount of nitrogen added in the process of molten steel smelting has the following steps: converter tapping, LF furnace refining process and continuous casting process. The slag and submerged arc operations reduce the amount of nitrogen absorption. The continuous casting process can also reduce the amount of nitrogen absorption by adding a cover to the ladle, sealing the nozzle with argon gas, and using an intrusive long nozzle. Steel process becomes bottleneck in reducing nitrogen content in steel

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Embodiment 1: Utilize the steelmaking method of converter tapping weak deoxidation to reduce nitrogen content in steel, be used for smelting low-alloy high-strength steel (manganese content is required to be 1.5~1.7% in steel), and its process steps are as follows:

[0018] 1. Desulfurization: the molten iron is desulfurized by the molten iron pretreatment station, and the sulfur content of the molten iron leaving the station is kept at 0.0035%;

[0019] 2. Soft stirring with argon gas: add 145.9 tons of desulfurized hot metal and 5.07 tons of scrap steel to the top-bottom combined blowing converter, and carry out blowing. At the end of the smelting period, stop blowing, and bottom blow argon for 8 minutes before tapping;

[0020] 3. Tapping with slag blocking: Tapping with slag blocking during tapping, add 2591kg of ferromanganese, 200kg of synthetic slag, 400kg of lime to the ladle, 45cm thick of ladle slag, and the manganese content in the molten steel is 1.16%.

[0...

Embodiment 2

[0023] Embodiment 2: Utilize the steelmaking method of converter tapping weak deoxidation to reduce nitrogen content in steel, smelt low-alloy high-strength steel (manganese content in steel is required to be 1.55~1.75%), and its process steps are as follows:

[0024] 1. Desulfurization: the molten iron is desulfurized by the molten iron pretreatment station, and the sulfur content of the molten iron leaving the station is kept at 0.0038%;

[0025] 2. Soft stirring with argon gas: add 144.6 tons of desulfurized hot metal and 9.6 tons of scrap steel to the top-bottom combined blowing converter for blowing. At the end of smelting, stop blowing, and bottom blow argon for 7 minutes before tapping;

[0026] 3. Tapping with slag blocking: when tapping, 2619kg of ferromanganese, 209kg of synthetic slag, 454kg of lime are added to the ladle, the thickness of ladle slag is 50cm, and the manganese content in the molten steel is found to be 1.19% through laboratory tests;

[0027] 4. Hoi...

Embodiment 3

[0029] Embodiment 3: Utilize the steelmaking method of converter tapping weak deoxidation to reduce nitrogen content in steel, smelt low-alloy high-strength steel (manganese content in steel is required to be 1.5-1.7%), and its process steps are as follows:

[0030] 1. Desulfurization: The molten iron is desulfurized by the molten iron pretreatment station, and the sulfur content of the molten iron leaving the station is kept at 0.004%.

[0031] 2. Soft stirring with argon gas: add 145.2 tons of desulfurized hot metal and 10.24 tons of scrap steel to the top-bottom combined blowing converter, and carry out blowing. At the end of the smelting period, stop blowing, and bottom blow argon for 9 minutes before tapping;

[0032] 3. Tapping with slag blocking: when tapping, 2686kg of ferromanganese, 211kg of synthetic slag, 445kg of lime are added to the ladle, the thickness of ladle slag is 50cm, and the manganese content in the molten steel is found to be 1.2% through laboratory tes...

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PUM

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Abstract

The invention discloses a steel-making method for reducing nitrogen content in steel by utilizing the weak deoxidation of tapping of a converter, which comprises the following steps: performing desulfurization, wherein molten iron is desulfurized through a molten iron pretreatment station, and the sulfur content of the molten iron taken out of the station is ensured to be lower than 0.04 percent; performing soft argon stirring, wherein a top and bottom combined blown converter is adopted to smelt molten steel, and the time of the soft argon stirring at a smelting terminal is between 5 and 10 minutes; performing slag-stopping tapping, wherein the slag-stopping tapping is performed during the tapping to ensure that slag thickness in a ladle is not more than 50cm, lime, ferromanganese and synthetic slag calcium aluminate are added into the ladle during the tapping, and no deoxidizing agent is added; and then hoisting the ladle to an LF position, making and refining reducing slag, and performing continuous casting to obtain the steel after deoxidation, the desulfurization and full alloying. By adopting the steel-making process, the nitrogen content of a steel billet is between 15 and 25ppm, and the nitrogen content in the steel is between 20 and 30ppm; the method does not need to add new equipment or retrofit old equipment, and has simple and easy operation; in addition, no deoxidizing agent is added, so the method can reduce steel-making cost and has good application prospect.

Description

Technical field: [0001] The invention belongs to the field of iron and steel metallurgy, and mainly relates to a steelmaking method for reducing nitrogen content in steel during iron and steel smelting. Background technique: [0002] Under normal circumstances, nitrogen is regarded as an impurity element in steel. When the nitrogen content in steel is high, it can cause aging embrittlement of steel, reduce the impact toughness of steel, and also cause adverse effects such as cold brittleness of steel. Nitride The precipitation of steel has a very significant effect on improving the yield strength of steel. When heated to a temperature range of 250-450 ° C, its surface turns blue, the strength of the steel increases, the impact toughness decreases, and the phenomenon of "blue brittleness" occurs. It can be seen that, Reducing the nitrogen content in steel can improve the toughness index of steel. As users have increasingly stringent requirements on steel quality, reducing th...

Claims

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Application Information

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IPC IPC(8): C21C5/28C21C7/064C21C5/30
Inventor 李子林段贵生毛尽华陈波刘海强李新林黄重李明儒苏晓峰张景宜陈丛虎郭永谦付振鹏张远强孙玉强齐新霞
Owner ANYANG IRON & STEEL GRP