A method for increasing nitrogen by blowing nitrogen at the bottom of a ladle

Abstract

The inventiondiscloses a steel ladle bottom nitrogen blowing and adding method. The method process comprises the steps of firstly, calculating nitrogen partial pressure PN2 according to the formula (I); secondly, calculating the bottom blowing gas total pressure P<total> according to the formula (II); thirdly, calculating the argon partial pressure PAr according to the formula (III); and fourthly, setting pressure of the nitrogen and pressure of the argon according to the nitrogen partial pressure PN2 and the argon partial pressure PAr and performing steel ladle bottom blowing at the same time. According to the method, through control over the partial pressure of the nitrogen in the argon and nitrogen mixed gas in the steel ladle bottom nitrogen blowing process, nitrogen adding for nitrogenous steel can be achieved accurately, use of high-cost nitralloy is reduced, and the defect of low control accuracy of sectional bottom nitrogen blowing and adding is prevented; adding of the high-cost nitralloy can be prevented, and high nitrogen mass fraction hit rate can be guaranteed; the steel ladle bottom nitrogen blowing and adding method has the characteristics of being low in cost, high in hit rate and easy to operate.

Description

technical field [0001] The invention relates to an alloy smelting method, in particular to a method for increasing nitrogen by blowing nitrogen at the bottom of a ladle. Background technique [0002] With the progress of society and the development of technology, users have higher and higher requirements for the strength, toughness and processing performance of steel. Some high-strength steels use nitrided alloys to strengthen the performance of steel. The finished steel has certain requirements for nitrogen content, making The control of nitrogen content in steel has become a key technology for the smelting of these steels. In the process of steelmaking, nitrogen addition to molten steel can be carried out by blowing nitrogen from the top of the ladle, blowing nitrogen from the bottom, or adding nitrided alloys. Ladle top blowing nitrogen requires an additional top blowing spray gun, which is rarely used due to high molten steel temperature, low spray gun life, unstable ni...

AI Technical Summary

Problems solved by technology

Ladle top blowing nitrogen requires an additional top blowing spray gun. During use, it is rarely used due to high molten steel temperature, low spray gun life, unstable nitrogen yield, and difficult nitrogen content to hit the target.

Although the addition of nitride alloys can ensure a high yield of nitrogen, the production cost is relatively high

For example, the Chinese Patent Publication No. CN103146875A discloses a method for smelting high-nitrogen steel under normal pressure. It needs to add 25-35 kg of manganese nitride to smelt 1 ton of steel, and the alloy cost per ton of steel is as high as 175-145 yuan / t of steel.

The cost of nitrogen-increasing treatment by blowing nitrogen at the bottom of the ladle is lower than that of nitrided alloys, but the nitrogen yield of conventional bottom-blowing nitrogen-increasing methods is low and unstable, and it is difficult to hit the steel nitrogen mass fraction control target

For example, a kind of nitrogen alloying process disclosed by the Chinese patent of the publication number CN101538636A is carried out with nitrogen in a ladle furnace, and a kind of nitrogen-increasing method of nitrogen-containing pure steel disclosed by the Chinese patent of the publication number CN101168817A, all adopt pure nitrogen gas alloying first Nitrogen is alloyed by stirring with pure argon and removing excess nitrogen, but it is difficult to select the switching point of nitrogen and argon in this method, which is not only complicated to operate but also has a low hit rate at the end point

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