RH refining method for removing inclusions in molten steel

Abstract

The invention provides an RH refining method for removing inclusions in molten steel. According to the method, nitrogen bottom blowing is carried out during the early and medium stages of RH vacuum treatment, and nitrogen serves as RH lift gas; a denitriding path in molten steel is controlled to prevent nitrogen elements in the molten steel from being removed from bubbles, application method the nitrogen separation and nitrogen increase process during vacuum treatment are carried out simultaneously to ensure that sufficient nitrogen elements are separated out from the molten steel with the inclusions as the core; and meanwhile, the effect of stably removing the inclusions in the molten steel is achieved under the condition that molten steel is continuously replaced and renewed in the RH refining process. The removal rate of small-size inclusions reaches up to 90% or more, the cleanliness of the molten steel is remarkably improved, and meanwhile, stable and continuous production can berealized at low cost.

Description

technical field [0001] The invention belongs to the field of metallurgical refining of iron and steel, in particular to an RH refining method for removing inclusions in molten steel. Used in high-quality special steels with strict requirements on inclusions, including bearings, springs, cord steels and other high-quality industrial wire rods in the RH refining production process, can significantly reduce the number of inclusions in steel (especially small-sized inclusions), Improve product quality. Background technique [0002] Non-metallic inclusions are an important factor affecting the fatigue life of high-quality special steel such as bearings, springs, and cords. The quantity and size of non-metallic inclusions in steel are important indicators to measure product quality. In the existing production process of high-quality special steel, the control of non-metallic inclusions is mostly through refining processes such as LF, RH or VD, and conventional refining processes ...

AI Technical Summary

Problems solved by technology

Although the above patents can reduce the effect of non-metallic inclusions in steel, there are problems in the following aspects: 1. The operation of increasing hydrogen (injecting hydrogen, coke oven gas, natural gas) into high-temperature liquid steel has relatively large Potential safety hazards, strict requirements on equipment sealing performance and daily gas pipeline leak detection, increase enterprise management costs; 2. The influence of oxygen and sulfur content in steel on the mass transfer of nitrogen in steel is not considered, and the reaction of nitrogen increase and nitrogen analysis The speed cannot be effectively controlled

3. The relationship between the denitrification pathway (internal precipitation of bubbles and removal from argon bubbles) and the de-inclusion effect in the vacuum denitrification process is not considered

Among them, if most of the nitrogen element in the molten steel is removed from the argon bubbles, the effect of removing tiny inclusions will not be achieved. The effect is not obvious

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