Method for preventing nitrogen increment of LF refined low-nitrogen steel

A low-nitrogen steel and converter technology, applied in the field of low-nitrogen steel smelting, can solve the problems of high argon cost, high cost, and difficult implementation, and achieve the effects of low production cost, reduced nitrogen increase, and reduced nitrogen increase amount

Inactive Publication Date: 2015-10-21
HEBEI IRON AND STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method needs to modify the electrode, and the cost of argon gas is high, which has the disadvantages of difficult implementation and high cost

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Embodiment 1: The method for refining low-nitrogen steel in this LF furnace to prevent nitrogen increase adopts the following specific processes.

[0023] 125 tons of molten steel tapped from the converter enters the station without encrustation, the entry temperature is 1493 degrees, the steel type is XY77B, and the N content before refining is 13ppm; according to the key requirements before the furnace, 400kg of fine ash and 200kg of fluorite are added during the tapping process. Large argon stirring is not allowed when entering the refining station, and the argon gas is controlled at 50Nm / l. Flow rate) is controlled at 86Nm / l, the supplementary component is controlled at argon flow rate of 157Nm / l, and the dissolution of carbon powder is promoted by means of electrode heating. The flow of argon gas is controlled at 36Nm / l by soft blowing. The process heating adopts 4 gears and 36000 heating mode. After the treatment is completed, the silicon-calcium line is fed for 3...

Embodiment 2

[0024] Embodiment 2: The method for refining low-nitrogen steel in this LF furnace to prevent nitrogen increase adopts the following specific process.

[0025] Adopt 125 tons LF refining furnace. The molten steel tapped from the converter enters the station without encrustation, the entry temperature is 1482 degrees, the steel type is XY77B, and the N content before refining is 20ppm; 450kg of small grain ash and 200kg of fluorite are added during the tapping process according to the key requirements before the furnace. Large argon stirring is not allowed in the refining station, and the argon gas is controlled at 40Nm / l. The order of feeding into the station is: 160kg of fluorite, 225kg of submerged arc slag, 425kg of small ash, 62.5kg of calcium carbide, and 87.5kg of deoxidizer; (Actual flow rate) is controlled at 90Nm / l, and the argon gas flow rate is controlled at 146Nm / l by supplementary components, and the dissolution of carbon powder is promoted by means of electrode h...

Embodiment 3

[0026] Embodiment 3: The method for refining low-nitrogen steel in this LF furnace to prevent nitrogen increase adopts the following specific process.

[0027] Adopt 125 tons LF refining furnace. The molten steel tapped from the converter enters the station without crust, the entry temperature is 1490 degrees, the steel type is XY77B, and the N content before refining is 15ppm; according to the key requirements before the furnace, 500kg of small grain ash and 200kg of fluorite are added during the tapping process. Large argon stirring is not allowed in the refining station, and the argon gas is controlled at 60Nm / l. The order of feeding into the station is: 200kg of fluorite, 210kg of submerged arc slag, 398kg of small ash, 31.25kg of calcium carbide, and 96kg of deoxidizer; during the heating process, argon ( The actual flow rate) is controlled at 88Nm / l, the argon gas flow rate is controlled at 150Nm / l, and the dissolution of carbon powder is promoted by means of electrode h...

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Abstract

The invention discloses a method for preventing nitrogen increment of LF refined low-nitrogen steel. The method comprises the following steps: allowing molten steel tapped from a converter to enter a station, and carrying out argon stirring under an argon flow of 30-60Nm/l; sequentially adding fluorite, submerged arc slag, small-grain ash, calcium carbide and a deoxidizer in the LF refining process; and selecting a high-grade heavy-current heating mode of the above LF furnace. The method avoids exposure of the molten steel through controlling the argon flow amount without changing present devices or refractory, shortens the existence time of high temperature slag through controlling the heating grade and the current value, avoids slag agglomeration induced long-time heating and stirring through controlling the charging sequence, and reduces the nitrogen absorption of the molten steel in a low oxygen state through controlling the deoxidation moment in order to reduce the nitrogen increment of the molten steel in the refining process. The method has the characteristics of production of low-carbon steel through fully utilizing present conditions of refining without vacuum treatment, easy realization and low production cost.

Description

technical field [0001] The invention relates to a method for smelting low-nitrogen steel, in particular to a method for preventing nitrogen increase by refining low-nitrogen steel in an LF furnace. Background technique [0002] Since nitrogen is a harmful element in the production of some steel types, it can combine with TI or AL of the steel type to form (TiN) or (AlN), which weakens the grain boundary strength, reduces the toughness, welding performance, and toughness of the thermal stress zone of the steel. Especially in the production of hard wire steel, it is easy to cause quality fluctuations. During the operation of the refining furnace, heating and feeding the line is a serious process of absorbing nitrogen, and due to the different operators and the different conditions of the molten steel entering the station, the nitrogen content in the molten steel is extremely unstable, and the nitrogen content of individual furnaces will exceed Finished product requirements, r...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C7/06C21C7/076C21C7/00
CPCY02P10/20
Inventor 国富兴连庆康毅盖少群李亚厚张艳丽
Owner HEBEI IRON AND STEEL
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