Method of ultra-low-carbon steel dephosphorization outside furnace

Abstract

The invention provides a method of ultra-low-carbon steel dephosphorization outside a furnace. According to the invention, a converter tapping target temperature is reduced, and small-particle lime is added to a ladle according to a proportion that 2.3-3.1kg of the small-particle lime is added to every ton of steel; during an LF refining process, appropriate amounts of lime and refining slag are respectively added, increased-temperature slagging is carried out, and temperature compensation is controlled; when the temperature increasing process is finished, and the slag is completely melted, an argon stirring dephosphorization process is carried out. According to the invention, temperature controlling is carried out, appropriate amounts of lime and refining slag are respectively added to the ladle and the LF furnace, and dephosphorization is carried out with the argon stirring measure, such that thermo-dynamical and dynamical conditions of dephosphorization are improved, and the controlling level of phosphorus in ultra-low-carbon steel is improved. With the method, an average dephosphorization rate after tapping is above 35%, steel judgment accidents and economic loss caused by standard-exceeding phosphorus content are reduced, and qualification rate of ultra-low-carbon steel quality is improved.

Description

technical field [0001] The invention belongs to the technical field of steelmaking technology, and in particular relates to a method for dephosphorizing ultra-low carbon steel outside a converter furnace. Background technique [0002] At present, the production process of domestic ultra-low carbon steel is generally carried out in the order of converter and vacuum circulation degassing furnace (referred to as RH furnace), and generally does not pass through the ladle refining furnace (referred to as LF furnace). Since the RH furnace is required to heat up as little as possible or not to heat up during the refining production process, so as not to pollute the molten steel, it is required that the tapping temperature of the converter should be high when producing ultra-low carbon steel. According to the thermodynamic conditions of dephosphorization, high-temperature tapping of converter is not good for dephosphorization. On the other hand, most of the finished product phosphor...

AI Technical Summary

Problems solved by technology

According to the thermodynamic conditions of dephosphorization, the high-temperature tapping of the converter is not good for dephosphorization. On the other hand, most of the finished phosphorus of ultra-low carbon steel is required to be controlled below 0.012%, which brings certain difficulties to the smelting control of the converter.

If the control is not good, the phosphorus content of ultra-low carbon steel will exceed the standard. The direct consequence is to change the steel treatment, which will not only affect the qualified rate of steel quality and economic benefits, but also affect the delivery rate of products.