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Multi-segment combined nitrogen control method of high-strength microalloyed steel

A micro-alloyed steel, high-strength technology, applied in the field of multi-stage combined nitrogen control of high-strength micro-alloyed steel, can solve the problems of harmfulness, plasticity and toughness reduction, etc.

Inactive Publication Date: 2017-06-13
HEBEI IRON AND STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] The role of nitrogen in steel is both beneficial and harmful. For example, nitrogen can replace part of the alloy in stainless steel. Nitrogen can refine the grain and improve the strength of the material in vanadium-containing steel. Nitrogen becomes Beneficial elements; nitrogen in low carbon steel can cause cold and brittle materials, nitrogen in general steel can cause material aging, increase the hardness and strength of steel, but reduce plasticity and toughness, especially in the case of deformation aging , plasticity and toughness decrease significantly
Aging phenomena are therefore detrimental for low alloy steels

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] Production of C700L high-strength microalloy automotive steel, 16308199 heats, the composition of the semi-steel after vanadium extraction is C: 3.97%, P: 0.072%, S: 0.017%, and the temperature is 1385℃; the semi-steel is smelted in the converter, and the smelting end point C: 0.04%, P: 0.009%, S: 0.019%, temperature 1685℃, use 680℃ turnover ladle for tapping, blow argon 2min before tapping, add 2kg / t of pre-melted refined slag when tapping 1 / 5, add High-quality small-grain lime 1.2kg / t, add ferro-niobium, ferrovanadium, low-carbon ferromanganese, and Taiwan aluminum alloy when tapping 1 / 4, and add it when tapping 3 / 4, the order of addition is to add the weaker deoxidizing ability first. After adding alloy material with strong deoxidizing ability, the addition amount is 88% of the target composition. After tapping, argon was blown and stirred at the argon blowing station for 2 minutes. The result of oxygen determination was 8ppm. The nitrogen content was determined to be...

Embodiment 2

[0023] Production of C700L high-strength microalloy automotive steel, 16101786 heats, the composition of the semi-steel after vanadium extraction is C: 4.07%, P: 0.053%, S: 0.015%, and the temperature is 1389℃; the semi-steel is smelted in the converter, and the smelting end point C: 0.04%, P: 0.007%, S: 0.016%, temperature 1675℃, use 640℃ turnover ladle for tapping, blow argon for 2 minutes before tapping, add 2kg / t of pre-melted refined slag when tapping 1 / 5, Add high-quality small-grain lime 1.2kg / t, add ferro-niobium, ferrovanadium, low-carbon ferromanganese, Taiwan aluminum alloy when tapping 1 / 4, and add it when tapping 3 / 4, the order of addition is first to add the weak deoxidizing ability After adding alloy material with strong deoxidizing ability, the addition amount is 85% of the target composition. After tapping, argon was blown and stirred at the argon blowing station for 2 minutes. The result of oxygen determination was 4ppm. The nitrogen content was determined to ...

Embodiment 3

[0025] Production of C750L high-strength microalloy automotive steel, 16306970 heats, the composition of the semi-steel after vanadium extraction is C: 4.2%, P: 0.058%, S: 0.019%, and the temperature is 1379℃; the semi-steel is smelted into the converter, and the smelting end point C: 0.05%, P: 0.010%, S: 0.019%, temperature is 1679℃, use 660℃ turnover ladle for tapping, blow argon 2min before tapping, add 2kg / t of pre-melted refined slag when tapping 1 / 5, add High-quality small-grain lime 1.5kg / t, add ferro-niobium, ferro-vanadium, low-carbon ferromanganese, and Taiwan aluminum alloy when tapping 1 / 4, and add it when tapping 3 / 4. The order of addition is to add the weaker deoxidizing ability first. After adding alloy material with strong deoxidizing ability, the addition amount is 86% of the target composition. After tapping, argon was blown and stirred at the argon blowing station for 2 minutes. The result of oxygen determination was 13ppm. The nitrogen content was determined...

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Abstract

The invention discloses a multi-segment combined nitrogen control method of high-strength microalloyed steel. The multi-segment combined nitrogen control method comprises the following steps: a converter vanadium extracting process, a converter melting process, an LF (Ladle Furnace) refining process and a slab continuous casting protective casting process; the content of finished steel of the microalloyed steel is less than or equal to 0.005 percent. According to the multi-segment combined nitrogen control method disclosed by the invention, a slag layer with a certain thickness is formed on the surface of molten steel, so that a function of isolating air is obtained; a mode of firstly adding alloy materials with weak deoxidizing capacity and then adding alloy materials with strong deoxidizing capacity is adopted, so that the phenomenon of nitrogen increment caused by contact between the molten steel with the air due to a strong deoxidizing reaction in a steel ladle is prevented from happening; after tapping is ended, a steel ladle car can be driven to an argon blowing operation station, argon blowing and stirring can be carried out for 2 minutes, and the content of O in the molten steel is regulated to be less than or equal to 0.002 percent; the electric heating time is controlled through LF refining, calcium carbide is added in batches during a refining and heating process, so that furnace slag can be formed into good foam slag, the foam slag covers the surface of the molten steel to form a protective layer, and direct contact between the air and the molten steel is isolated. Through combined control of the processes, the microalloyed steel is finally obtained, and the content of N in the finished steel of the microalloyed steel is less than or equal to 0.005 percent.

Description

Technical field [0001] The invention belongs to the technical field of metallurgy, and specifically relates to a multi-stage combined nitrogen control method for high-strength microalloy steel. Background technique [0002] The role of nitrogen in steel has both beneficial and harmful aspects. For example, nitrogen can replace part of alloys in stainless steel. Nitrogen can refine grains in vanadium-containing steels and increase the strength of materials. Beneficial element; Nitrogen can cause cold brittleness of materials in low-carbon steel. Nitrogen can cause material aging in general steel, increasing the hardness and strength of steel, but reducing plasticity and toughness, especially in the case of deformation and aging , Plasticity and toughness decrease significantly. Therefore, the aging phenomenon is harmful to low alloy steel. [0003] On the other hand, due to the combination of nitrogen and the microalloying elements in the steel, the continuous casting billet crack...

Claims

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Application Information

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IPC IPC(8): C21C7/072C21C5/30C22B9/10B22D27/00
CPCC21C7/072B22D27/003C21C5/30C22B9/103
Inventor 薛启河王宝华徐立山程玉君于静张晓磊
Owner HEBEI IRON AND STEEL
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