Ultra-low phosphorus steel smelting method

Abstract

The invention discloses an ultra-low phosphorus steel smelting method. Dephosphorizing pretreatment is conducted firstly, and then operation is conducted through a double slag method. A dephosphorization period and a blowing period are included. According to the dephosphorization period, a dephosphorization agent and pre-slag left by a previous converter serve as slagging materials to be subjectedto dephosphorization smelting, and alkali converter slag is obtained; according to the blowing period, primary blowing is conducted, specifically, the oxygen flow rate during primary blowing is appropriately decreased, the converter bottom blowing strength is larger than or equal to 0.045 Nm<3> / (t.min), the oxygen-supplying blowing time is 6-7 min, after primary blowing is completed, converter slag is discharged, and then new slag is added to be slagged again; and the final converter slag alkalinity of secondary blowing is controlled to be 3.5-4.5, the content of FeO is 18-25%, the content ofMgO is 8-10%, the final temperature is 1600-1630 DEG C, the content of final C is 0.03-0.06%, a special slag-stopping plug is adopted before steel taping, after 3 / 4 steel taping is conducted, a slag-stopping awl is additionally arranged, and 40-60% of later-period slag which is generated after secondary blowing is finished is left to serve as a slagging material of later converter steel. Throughthe technology, the converter final P can be stably controlled to be 0.005% or below.

Description

[0001] This application is a divisional application with application number 2015105484814, application date August 31, 2015, and invention name "A Method for Smelting Ultra-low Phosphorus Steel". technical field [0002] The invention belongs to the field of metal material smelting, and in particular relates to a method for smelting ultra-low phosphorus steel. Background technique [0003] Phosphorus is a harmful element for most steel types and needs to be removed as much as possible during the smelting process. Phosphorus is prone to segregation during the solidification process of steel. When the phosphorus content in the steel is greater than 0.015wt%, the segregation of phosphorus increases sharply, which significantly reduces the low-temperature impact toughness and tempering toughness of the steel, and increases the brittle transition temperature of the steel, resulting in cold and brittle , It also deteriorates the weldability of steel. Pipeline steel, oil well pipe...

AI Technical Summary

Problems solved by technology

The commonly used flux mainly includes fluorite, which can reduce the viscosity and melting temperature of slag, increase the slag forming speed of slag in the dephosphorization period, and improve the kinetic conditions of dephosphorization reaction, but fluorite has serious corrosion on the converter lining, and will Pollution to the environment, so try to avoid using fluorspar

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