Method for adding nitrogen into steel ladle

A ladle and molten steel technology, applied in the field of ladle nitrogen increase, can solve problems such as increased production costs

Inactive Publication Date: 2012-10-10
SHANXI TAIGANG STAINLESS STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0002] For high-nitrogen steel types (such as dual-phase steel series steel types), the requirements for N in their products are relatively high, usually greater than 1500ppm to 2000ppm, but sometimes due to process control deviations, the N content in molten steel

Method used

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Examples

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Embodiment

[0045] In this embodiment, the duplex steel series steel grade (S31803) is taken as an example, and the amount of molten steel for tapping is 45t.

[0046] The mass percentage ratio of the chemical composition of this steel type is:

[0047] C: 0.01%~0.03% Si: 0.40%~0.60% Mn: 1.0%~1.5% P≤0.03% S≤0.003% Cr: 22.00%~23.00% Ni: 5.00%~5.50% N: 0.1500%~0.1800% Mo: 3.00% to 3.50%

[0048] The rest is Fe and unavoidable impurities.

[0049] After the AOD taps the steel, the components are sampled and analyzed in the ladle as follows:

[0050] C: 0.019% Si: 0.478% Mn: 1.11% P: 0.027% S: 0.002% Cr: 22.46% Ni: 5.13% N: 0.1395% Mo: 3.182%

[0051] The rest is Fe and unavoidable impurities.

[0052] It can be seen that the N content is 1395ppm, which is lower than the target lower limit of 1500ppm, and other components meet the control requirements, so it is necessary to increase nitrogen in LF to make the nitrogen content meet the control requirements.

[0053] This embodiment is the...

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Abstract

The invention relates to a method for adding nitrogen into a steel ladle. The method includes the following steps in sequence: (I) a steel ladle loaded with molten steel suitable for ladle furnace (LF) smelting is moved to an LF station; (II) according to the low limit of nitrogen content in the steel grade, the nitrogen content difference in AOD (argon oxygen decarburization) tapping and the amount of tapped molten steel, nitrogen to be replenished is calculated by the formula: (NL-NA)*MA*1000=G; the flow of nitrogen per minute is set as V which is converted into weight M by the formula: V/22.4*28=M; the nitrogen absorption of high-nitrogen molten steel is 95%+/-4%, the time of bottom nitrogen blowing is not shorter than T which is calculated by the formula: G*1000/M/(95%+/-4%), and nitrogen blowing T is added by 3 to 4 minutes. NL is the lower limit of nitrogen content in the smelted high-nitrogen steel; NA is the nitrogen content in the tapping of an AOD furnace; MA is the weight of the molten steel; and M is the weight of bottom-blown nitrogen per minute; and (III) the nitrogen-blowing operation is finished, and sample is taken out of the steel ladle and analyzed. The amount of nitrogen added by the method for adding nitrogen into the steel ladle can meet the requirement of high-nitrogen steel grades, and the time of adding nitrogen can be easily controlled.

Description

technical field [0001] The invention relates to a method for increasing nitrogen in a ladle. Background technique [0002] For high-nitrogen steel types (such as dual-phase steel series steel types), the requirements for N in the products are relatively high, usually greater than 1500ppm to 2000ppm, but sometimes due to process control deviations, the N content in the molten steel after tapping is slightly biased. Low, less than the lower limit of the target, it is particularly important to take effective remedial measures to avoid the generation of substandard products, and some have to go back to the furnace for re-smelting, resulting in increased production costs. Contents of the invention [0003] In order to overcome the above-mentioned shortcomings of the existing methods for increasing nitrogen in ladles, the present invention provides a method for increasing nitrogen in ladles in which the amount of nitrogen added meets the requirements of high-nitrogen steel grade...

Claims

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Application Information

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IPC IPC(8): C21C7/072
Inventor 谭建兴刘明生武鹏张耀龙刘睿智闫建新段鹏飞李强
Owner SHANXI TAIGANG STAINLESS STEEL CO LTD
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