Method for nitriding molten steel stably

Abstract

The invention discloses a method for nitriding molten steel stably, which comprises the following step of refining the molten steel in a ladle furnace (LF). The method is characterized by comprising the following step of: nitriding in an electric arc area by using a nitriding gun in the slagging process after the molten steel enters the LF, wherein the nitriding gun comprises an air blow main pipe (5), a protective pipe (7) and a gun body fixing device (6); the protective pipe (7) is approximately in a Y shape; the air blow main pipe (5) is fixed in the protective pipe (7); and a plurality ofspray orifices (13) are formed at inner arcs of arc sections (15 and 16) of the air blow main pipe (5) and arc sections (11 and 14) of the protective pipe (7). In the method, the nitriding effect is stable, and the utilization rate of nitrogen is up to over 75 percent; and the nitrogen blowing time is short, nitriding of the molten steel can be completed in the normal process of electric furnace heating without the prolonging of the smelting time, and the average nitriding amount of the molten steel is 0.0143 percent.

Description

technical field [0001] The invention belongs to the refining technology outside the furnace, in particular to a method for increasing nitrogen in molten steel in the LF refining process. Background technique [0002] In the iron and steel industry, most steel types require low nitrogen content, and the smelting process is often controlled at a low nitrogen content. However, some steel grades have different uses, and some steel grades require a certain amount of nitrogen, and the nitrogen in the steel is required to exist in the form of solid solution in the steel, and the nitrogen element produces solid solution strengthening, which can improve its corrosion resistance , improve the strength of the steel, improve the corrosion resistance of the welded joints of the steel, improve the overall pitting corrosion resistance of the material, and reduce the tendency of selective corrosion. In the smelting process, especially in the refining process, it is necessary to add a certa...

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Problems solved by technology

[0003] In the prior art, there are mainly two ways to increase nitrogen in molten steel: one is to add a solid nitrogen-containing alloy, which is added to the liquid steel in the later stage of refining in the steelmaking process, and the nitrogen element in the nitrogen-containing alloy is absorbed The molten steel is absorbed to make the molten steel reach a certain nitrogen content; the disadvantage of this method of increasing nitrogen is that the smelting cost is high, and the nitrogen absorption stability of the steel is poor, which easily leads to large fluctuations in the nitrogen content in the molten steel, and even nitrogen Composition out of standard range

This method can increase the nitrogen content in molten steel at a lower cost, but this method significantly prolongs the smelting time, and the nitrogen blowing time is longer, generally more than 15 minutes, and the cleaning time is also more than 10 minutes. At least prolong the smelting cycle for more than 25 minutes, the nitrogen yield is low and unstable

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