Technique for manufacturing ultra-low phosphate steel by molten steel refining and dephosphorizing outside furnace

Abstract

The present invention relates to a method for controlling phosphorus in micro-alloy steel, high-carbon steel and special steel to produce ultra-low-phosphorus steel, especially a process for producing ultra-low-phosphorus steel by refining and dephosphorizing molten steel outside the furnace, comprising the following steps: ① Converter tapping: the temperature is 1550℃~1660℃, the phosphorus content is below 0.02%, and the steel is tapped with non-deoxidation and slag blocking treatment; 5~20kg / t; ③Deep dephosphorization: adjust the position of the feeding pipe and the descending pipe so that they are on the opposite side of the feeding pipe, the ladle is transported to the RH station, vacuumized, and the composite ball is put into the RH high-level silo, and the cycle 0.1~15min; ④Slagging: breaking vacuum, removing slag, adding ladle covering agent; ⑤Heating and stirring: heating and stirring in the refining furnace, and the heating temperature is controlled at 1580~1620℃; ⑥Deoxidation, alloying refining treatment: ⑦Continuous casting : Continuous casting adopts full protection pouring.

Description

technical field [0001] The invention relates to a method for controlling phosphorus in micro-alloy steel, high-carbon steel and special steel to produce ultra-low-phosphorus steel, especially a process for producing ultra-low-phosphorus steel by refining and dephosphorizing molten steel outside the furnace. The invention belongs to metallurgical technology field. Background technique [0002] It is well known that phosphorus is usually controlled as a harmful element in steel. Because the segregation of phosphorus in the steel is serious, the toughness of the steel is deteriorated, resulting in "cold brittleness", especially at low temperature conditions, it is more likely to occur "cold brittleness", and the segregation of phosphorus will also cause the anisotropy of the steel, reducing the Welding performance, causing corrosion fatigue of stainless steel. With the rapid development of science and technology, high-grade high-quality steel has continuously improved the met...

AI Technical Summary

Problems solved by technology

For this reason, most of the current steel mills use the "double slag method", that is, two slagging in the converter smelting, or the "duplex method", that is, one converter is used to smelt molten iron for half the time and then pour it into another converter to continue smelting. method, the shortcomings of these two methods are that the process is complex, the smelting time is long, and the productivity of the converter cannot be fully utilized; there is another way to carry out "three removals" on the molten iron in advance, that is, desiliconization, desulfurization, and dephosphorization, such as Japanese iron and steel companies , its disadvantage is that it requires a lot of equipment, large investment, complex process, large heat loss, and because the temperature of molten iron after "three removals" is low, the amount of scrap steel added during converter smelting is greatly reduced

Therefore, in order to produce these low-phosphorus and ultra-low-phosphorus steels, conventional converter smelting can no longer meet the phosphorus requirements of these steel types, so it is urgent to study the method of assisting dephosphorization by refining outside the furnace, so as to realize the production of ultra-low-phosphorus steel