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Method for increasing nitrogen content in steel

A nitrogen content, oxygen and nitrogen technology, applied in the manufacture of converters, etc., can solve the problems of high cost and low efficiency of nitrogen addition in molten steel, and achieve the effects of increasing nitrogen content, reducing smelting difficulty, and reducing alloy and process costs

Pending Publication Date: 2021-09-03
CHONGQING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a method for increasing the nitrogen content in steel, which is used to solve the problems of low efficiency and high cost of nitrogen increase in molten steel in the prior art, so as to meet the needs of different steel types. Different requirements for nitrogen content under different process routes

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] Set the initial oxygen step of mixed blowing of oxygen and nitrogen to 60%, the ratio of oxygen to nitrogen to 3:1, the blowing time of nitrogen to 2 minutes, and the total amount of blowing nitrogen to 1Nm 3 / t steel, 1 heat of steel is about 80t steel, that is, the total amount of nitrogen blowing is 80Nm 3 / furnace;

[0032] When the blowing reaches 60% of the initial oxygen step, nitrogen and oxygen are simultaneously blown in at the set oxygen-nitrogen ratio through the oxygen lance;

[0033] When tapping the converter, 1.2 kg / t steel silicon-vanadium alloy is added to the molten steel for nitrogen fixation; the nitrogen content of the finally obtained tundish molten steel is 100 ppm.

Embodiment 2

[0035] Set the initial oxygen step of mixed blowing of oxygen and nitrogen to 62.5%, the ratio of oxygen to nitrogen to 3.5:1, the blowing time of nitrogen to 3 minutes, and the total amount of blowing nitrogen to 1.875Nm 3 / t steel, 1 heat of steel is about 80t steel, that is, the total amount of nitrogen blowing is 150Nm 3 / furnace;

[0036] When the blowing reaches 62.5% of the initial oxygen step, nitrogen and oxygen are blown in at the same time through the oxygen lance to set the ratio of oxygen to nitrogen;

[0037] When tapping the converter, 1.2kg / t steel silicon-vanadium alloy is added to the molten steel for nitrogen fixation; the nitrogen content of the finally obtained tundish molten steel is 103ppm.

Embodiment 3

[0039] Set the initial oxygen step of mixed blowing of oxygen and nitrogen to 80%, the ratio of oxygen and nitrogen to 6:1, the blowing time of nitrogen to 4.5 minutes, and the total amount of blowing nitrogen to 4Nm 3 / t steel, 1 heat of steel is about 80t steel, that is, the total amount of nitrogen blowing is 320Nm 3 / furnace;

[0040] When the blowing reaches 80% of the initial oxygen step, nitrogen and oxygen are blown in at the same time through the oxygen lance to set the ratio of oxygen to nitrogen;

[0041] When tapping the converter, 1.2kg / t steel silicon-vanadium alloy is added to the molten steel for nitrogen fixation; the nitrogen content of the finally obtained tundish molten steel is 119ppm.

[0042] To sum up, in a method for increasing the nitrogen content in steel provided by the embodiment of the present invention, by setting different oxygen and nitrogen blowing parameters of the converter oxygen lance, supplemented by nitrogen blowing at the bottom of the...

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Abstract

The invention provides a method for increasing the nitrogen content in steel, the method comprises the following steps that at the last stage of converter smelting, an initial oxygen step of oxygen-nitrogen mixed blowing is set according to a turning point of decarburization rate reduction at the last stage of blowing; the oxygen-nitrogen ratio, the nitrogen blowing time and the total nitrogen blowing amount are set according to the steel grade nitrogen requirement; when blowing reaches the initial oxygen step of oxygen-nitrogen mixed blowing, nitrogen and oxygen are blown into molten steel at the same time according to the oxygen-nitrogen ratio through an oxygen lance, and nitrogen blowing lasts for the nitrogen blowing time to reach the total nitrogen blowing amount; and during converter tapping, silicon-vanadium alloy is added into the molten steel for nitrogen fixation. The nitrogen content in the molten steel can be remarkably increased, the nitrogen content in the molten steel after tapping can reach 80-120 ppm so as to meet different requirements of different steel types for the nitrogen content under different process routes, nitrogen-containing alloy (HRB400E) is completely replaced, or nitrogen-containing alloy (HRB500E) is partially replaced, and the alloy cost and the smelting difficulty are reduced under the condition that the requirements for the nitrogen content and the strength of twisted steel are met.

Description

technical field [0001] The invention belongs to the technical field of smelting technology, and in particular relates to a method for increasing nitrogen content in steel carried out in the later stage of converter smelting. Background technique [0002] Rebars account for a large proportion of steel products in my country, and vanadium nitrogen microalloying is the most widely used microalloying process to increase the strength of rebars. Some enterprises use abundant and cheap nitrogen as a raw material, blowing nitrogen into the molten steel to make the molten steel reach a certain nitrogen content, which can greatly reduce the production cost of steel. It is an important technology in the production of nitrogen-containing steel at present. . [0003] Generally, there are three methods for increasing molten steel nitrogen by blowing nitrogen from the bottom of the converter, nitrogen by blowing nitrogen from the bottom of the ladle, and increasing nitrogen by nitrogen-co...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C7/072C21C7/00C21C5/35
CPCC21C7/072C21C7/0006C21C5/35
Inventor 廖明文敏程殿张俊张杰新王田杨金伟陈鸿员
Owner CHONGQING IRON & STEEL CO LTD
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