High-purity duplex stainless steel smelting process with precise control of n content

Abstract

The invention discloses a high-purity duplex stainless steel smelting process with precisely controlled N content, which adopts the smelting method of "electric arc furnace + AOD furnace refining". Firstly, the initial melting is carried out in the electric arc furnace, and the furnace charge includes the steel return material, stainless steel return material, alloy, and auxiliary materials; then it enters the AOD furnace to refine the molten steel, blowing N throughout the refining process, through the ratio of oxygen to nitrogen, blowing gas Control the flow rate and time, blow nitrogen and oxygen mixed gas in 4 times for decarburization, through reduction, slagging, desulfurization, composition adjustment, precise control of N, tapping, casting and other steps, to achieve rapid decarbonization and precise control of N , and control P, S content, gas content and oxide inclusions to a lower level. In the electric arc furnace smelting stage, carbon is highly allocated, and in the early stage of AOD refining, the temperature is raised by carbon-oxygen reaction; S32205 stainless steel ingots that meet the standard requirements are produced, which greatly improves production efficiency and reduces production costs.

Description

technical field [0001] The invention relates to the technical field of stainless steel smelting, in particular to a high-purity duplex stainless steel smelting process with precisely controlled N content. Background technique [0002] Duplex stainless steel refers to the stainless steel whose solid solution structure is composed of ferrite and austenite. Each of ferrite and austenite accounts for about 50%. Generally, the content of lesser phases needs to reach at least 30%. Duplex stainless steel has the advantages of both ferritic stainless steel and austenitic stainless steel. Compared with austenitic stainless steel, duplex stainless steel has the advantage of higher mechanical properties, including solid solution strengthening, grain refinement, precipitation hardening , and has excellent resistance to stress corrosion and pitting corrosion. Compared with ferritic stainless steel, it has high toughness, low brittle transition temperature, good intergranular corrosion r...

AI Technical Summary

Problems solved by technology

[0006] There are currently two ways to increase nitrogen: one is to add ferrochromium nitride, but the recovery rate of N is not stable, and the cost of ferrochromium nitride is also higher; the other is to use nitrogen 2 Alloying method, blowing N into molten steel 2 , N has a certain solubility in molten steel, alloying can be achieved, and the cost is also low

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