Low-phosphorous steel smelting method of mixed blowing of oxygen and nitrogen of top blowing oxygen lance of converter

Abstract

The invention relates to a low-phosphorous steel smelting method of mixed blowing of oxygen and nitrogen of a top blowing oxygen lance of a converter, and belongs to the technical field of converter steelmaking. The low-phosphorous steel smelting method of mixed blowing of the oxygen and the nitrogen of the top blowing oxygen lance of the converter includes the following steps that firstly, blowing of a dephosphorizing phase is conducted in the converter, blowing time is controlled in 6-9min, and normal blowing is conducted after deslagging; top-blowing air is mixed gas of the nitrogen and the oxygen in the dephosphorizing phase of the converter; and raw materials which are used by steelmaking are melted iron scrap steel, and scrap ratio is 5%-15%. The low-phosphorous steel smelting method of mixed blowing of the oxygen and the nitrogen of the top blowing oxygen lance of the converter has the advantages that a part of nitrogen is mixed into the top-blowing gas in the dephosphorizing phase, so that low oxygen supply is reached, and simultaneously top-blowing gas supply strength is not reduced (top-blowing mixing intensity is not reduced). Control of molten bath temperature1300DEG C-1380DEG C in the dephosphorizing phase is reduced, and dephosphorizing rate of the dephosphorizing phase is improved, low-phosphorou and extremely low-phosphorous steel with fished phosphorous content lower than 60ppm is achieved. High-phorphorous molten iron can be adopted to smelt, blowing is stable, and dephosphorizing efficiency is high.

Description

technical field [0001] The invention belongs to the technical field of converter steelmaking, and in particular provides a low-phosphorus steel smelting method in which oxygen and nitrogen are mixed blown by a converter top oxygen lance; it can realize the smelting of low-phosphorus or even extremely low-phosphorus steel; it is suitable for converter dephosphorization Pretreatment and converter double slag smelting. Background technique [0002] Phosphorus is an element that is easy to segregate in steel. When the phosphorus content in steel is greater than 0.015%, the segregation of phosphorus increases sharply and increases the hardness of the segregation zone. At the same time, phosphorus also deteriorates the welding performance and significantly reduces the low temperature impact toughness of steel. Increase the brittle transition temperature of steel. At present, pipeline steel, steel for offshore platforms, steel for oil well pipes, and steel for low-temperature vess...

AI Technical Summary

Problems solved by technology

[0007] The present invention is a low-phosphorus steel smelting method in which oxygen and nitrogen are mixedly blown by an oxygen blowing lance on the top of a converter, which solves the above-mentioned problems such as lowered oxygen supply intensity in the dephosphorization pretreatment stage, which easily causes lower agitation intensity of the molten pool and poor dephosphorization effect, etc. Realize the smelting of low-phosphorus or even extremely low-phosphorus steel

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