Ladle furnace use nitrogen gas nitrogen alloying process

Abstract

The invention relates to a ladle furnace use nitrogen gas nitrogen alloying process. The process comprises the following steps: a) smelting nitrogen-contained stainless steel, controlling the components of the molten steel except the nitrogen to the targeted components, and controlling a nitrogen flush initial temperature at 30 to 50 DEG C above a refining treatment out-station temperature; b) during the nitrogen bottom blowing for the smelting of the nitrogen-contained stainless steel in the LF furnace, adding 1 to 20 ppm of nitrogen to each standard cube of nitrogen; c) during the nitrogen bottom blowing for the micro-alloying treatment, controlling the nitrogen flow at 6 to 120m<3> / h and the nitrogen flush pressure at 0.60 to 0.80 MPa; and d) when the nitrogen bottom blowing is finished, carrying out the argon bottom blowing for 4 to 6 minutes with the argon flow of 2 to 20 m<3> / h so as to average the stainless steel components and temperature. The process adds the nitrogen alloying function through the nitrogen bottom flowing to the ladle furnace (LF) in the prior stainless steel production process so as to replace a nitro alloy, make the nitrogen-contained stainless steel carry out continuous and stable nitrogen alloying in the ladle furnace, improve the purity of the molten steel, and consequently improve the molten steel quality and reduce the production cost.

Description

technical field [0001] The invention relates to a stainless steel smelting technology, in particular to a nitrogen alloying process using nitrogen in a ladle furnace (LF) for smelting nitrogen-containing stainless steel. Background technique [0002] Stainless steel refers to the general term for alloy steel that is resistant to corrosion by the atmosphere, acid, alkali and salt. The so-called "stainless steel" refers to its corrosion resistance, which can be attributed to the formation of a chromium oxide surface film in an oxidizing environment. This film has the characteristics of insolubility, self-healing and non-porous. Argon oxygen decarburization furnace (AOD) is one of the main refining methods for producing stainless steel. [0003] At present, 88% of stainless steel in the world is produced by two-step process, of which 76% is produced by AOD furnace. The ladle furnace (LF furnace) is one of the refining equipment installed between the AOD furnace and the contin...

AI Technical Summary

Problems solved by technology

[0020] (1) Nitriding alloys are not pure metals and contain impurities. Adding more nitriding alloys will pollute stainless steel molten steel, affect the purity of molten steel, and thus affect the quality of molten steel

[0021](2) If the target value of free nitrogen content is large at the beginning of smelting, more nitrided alloys need to be added, which will cause fluctuations in other alloy components and exceed the standard. Resulting in unqualified stainless steel components

[0022](3) The price of nitrided alloy is relatively expensive, adding more nitrided alloy will obviously increase the cost

[0023] (4) Since the slag shell of stainless steel is very hard, when adding nitrided alloys, part of the nitrided alloy is often added to the slag shell, which cannot be melted into molten steel, resulting in nitrogen Unstable yield and uneven nitrogen composition