A method for dephosphorizing molten steel

Abstract

The invention discloses a method for dephosphorizing molten steel, wherein the method includes: (1) controlling the end point of converter smelting, so that the phosphorus content in the obtained molten steel is not higher than 0.012% by weight, and the carbon content is 0.03-0.05% by weight %, the temperature is 1640-1680°C; (2) tap the molten steel obtained in step (1) into a ladle, add a pre-refining agent to the ladle, and carry out argon blowing refining, wherein the pre-refining agent includes active lime and fluorite; (3) The molten steel obtained after argon blowing and refining is subjected to RH vacuum treatment, wherein a dephosphorizing agent is added during the RH vacuum treatment, and the dephosphorizing agent includes active lime and iron oxide scale. The method can achieve the purpose of dephosphorization of molten steel, so that the phosphorus content in the treated molten steel is not higher than 0.007% by weight.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a method for dephosphorizing molten steel. Background technique [0002] Phosphorus is a harmful element in most steels. It has adverse effects on the surface quality, tensile strength, and stress corrosion resistance of steel. It is easy to segregate at grain boundaries, resulting in "cold and brittle" steel, which significantly reduces the low temperature impact toughness. In recent years, as users have increasingly stringent requirements for steel performance, higher requirements have been put forward for the phosphorus content of many steel types; Steel and tinplate require phosphorus to be less than 0.010% by weight; some aviation, atomic energy, and corrosion-resistant pipeline steels require finished phosphorus to be less than 0.005% by weight. Therefore, how to reduce the phosphorus content in molten steel has become a difficult problem in the production ...

AI Technical Summary

Problems solved by technology

This method has the following disadvantages: it is necessary to have strict requirements on the control of the oxygen content of molten steel. If the oxygen content of the tapping is too high, the phenomenon of "blasting" of the ladle may occur during the tapping process or after the tapping is completed, and there is a certain potential safety hazard. The deep dephosphorization agent must be added to the ladle before and after, and the molten steel should be weakly deoxidized. The process takes too long and affects the production efficiency.

This method has the following disadvantages: when the phosphorus content in the furnace is high, it is difficult to control the final phosphorus within 0.006% by weight by using the single slag method, and it is difficult to control the amount of slag in the tapping process.