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Method for reducing nitrogen content in steel

A technology of nitrogen content and molten steel, applied in the field of steelmaking, can solve the problems affecting the plasticity and toughness of high-strength steel, high nitrogen content of high-strength steel slabs, and long process steps, so as to prevent nitrogen increase, suppress nitrogen absorption, and reduce nitrogen content. low effect

Pending Publication Date: 2022-03-22
SHOUGANG CORPORATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] At present, because high-strength steel will add a variety of alloying elements in the composition, based on considerations such as desulfurization, more alloying elements, and inclusion control, the converter→LF→RH→CC process is generally adopted, and the process is relatively long, so The nitrogen increase in the smelting process is accumulated, and the high-strength steel slab produced has a high nitrogen content, and the slab cannot remove nitrogen during the rolling process, thus affecting the plasticity and toughness of the high-strength steel

Method used

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  • Method for reducing nitrogen content in steel
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Embodiment approach

[0032] As an implementation manner of the embodiment of the present invention, the loading amount of the scrap steel is 8-15% of the total loading amount.

[0033] In the present invention, steel scrap and molten iron are loaded into a converter for smelting. The converter is the most important link in controlling the nitrogen content of molten steel. Especially in the later stage of converter blowing, due to the weakening of the carbon-oxygen reaction, it is very easy to cause nitrogen increase in molten steel. Therefore, the present invention proposes to control The loading amount of scrap steel is 8-15% of the total loading amount, which ensures that the converter has sufficient heat. At the end of the converter, the molten steel will not be overoxidized due to insufficient heat, which will cause the molten steel to absorb nitrogen; on the other hand, it can also ensure the end temperature of the converter. Avoid the problem that the temperature of molten steel in the tundis...

Embodiment 1

[0058] Embodiment 1 provides a method for reducing the nitrogen content in steel. The method adopts the process route of 210t converter → RH → continuous casting, and adopts the following smelting process, specifically:

[0059] 1. Put the molten iron and steel scrap into the converter for converter oxygen blowing smelting to obtain converter smelting molten steel. Specifically, the total charging amount is 235t, wherein the charging amount of scrap steel is 8% of the total charging amount, when the oxygen supply in the converter smelting process is 85%, the adding amount of converter pellets is 8kg / t steel; The carbon content of the end point molten steel is 0.045%, the oxygen content is 0.04%, and the temperature is 1640°C.

[0060] 2. Tapping the converter smelting molten steel obtained in step 1 into a ladle to obtain tapping molten steel; adding a deoxidizer to deoxidize during the tapping process, and adding an alloy for alloying. Specifically, Si deoxidation is used to...

Embodiment 2

[0065] Embodiment 1 provides a method for reducing the nitrogen content in steel. The method adopts the process route of 300t converter → RH → continuous casting, and adopts the following smelting process, specifically:

[0066] 1. Put the molten iron and steel scrap into the converter for converter oxygen blowing smelting to obtain converter smelting molten steel. Specifically, the total charging amount is 328t, of which the charging amount of scrap steel is 11% of the total charging amount. When the oxygen supply in the converter smelting process is 87%, the adding amount of converter pellets is 11kg / t steel; The carbon content of the end point molten steel is 0.04%, the oxygen content is 0.04%, and the temperature is 1638°C.

[0067] 2. Tapping the converter smelting molten steel obtained in step 1 into a ladle to obtain tapping molten steel; adding a deoxidizer to deoxidize during the tapping process, and adding an alloy for alloying. Specifically, Si deoxidation is used ...

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Abstract

The invention provides a method for reducing the content of nitrogen in steel, which comprises the following steps: mixing scrap steel and molten iron, and smelting to obtain final molten steel; tapping deoxidation operation is conducted on the smelted molten steel, so that the mass fraction of oxygen in the molten steel is larger than or equal to 0.01%, and tapping molten steel is obtained; the tapping molten steel is subjected to RH refining treatment under the vacuum pressure of 0.067-0.50 KPa, and RH refined molten steel is obtained; and the RH refined molten steel is subjected to full-protection pouring, and the plate blank for the low-nitrogen-content steel is obtained. By adopting the method provided by the invention, the nitrogen content in the plate blank can be as low as 26-32ppm, the nitrogen content is low, the sulfur content is 0.0017-0.0019%, the requirement of high-strength steel is met, and the pouring process is smooth.

Description

technical field [0001] The invention belongs to the technical field of steelmaking, in particular to a method for reducing nitrogen content in steel. Background technique [0002] Due to the advantages of high strength, great potential for weight reduction, and good formability, high-strength steel is now more and more used to replace conventional varieties to better meet the development of green, high-efficiency, and low-carbon production. An important difficulty in the production of target high-strength steel lies in smelting, especially the elemental control of molten steel. Large fluctuations in the control of elements can lead to poor quality high-strength steels. In order to improve the strength, high-strength steel generally uses Mn, Ti and other alloying elements to increase the strength. In this context, if the nitrogen content of molten steel is high, it is easy to precipitate TiN precipitates or inclusions during solidification. When TiN When the size exceeds a ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C7/06C21C7/10C21C7/064C21C7/068
CPCC21C7/06C21C7/10C21C7/064C21C7/068Y02P10/20
Inventor 高攀朱国森龚坚韩少伟郭玉明江腾飞朱良赵晓东李海波刘风刚黄福祥黄桂斌马文俊刘道正朱克然刘珍童韩凯峰
Owner SHOUGANG CORPORATION
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