Technique for manufacturing ultra-low phosphoretic steel with outside-stove refining dephosphorization of liquid steel

Abstract

The invention relates to a method for controlling phosphorus in the production of ultra-low phosphorous steel by microalloy steel, high carbon steel and special steel, in particular to a process method for producing the ultra-low phosphorous steel by external refining dephosphorization of molten steel, which comprises the following steps of: 1) converter tapping: the temperature is between 1,550 and 1,660 DEG C, the content of the phosphorus is less than 0.02 percent, and the nondeoxidation and the slag-stopping treatment are adopted for tapping; 2) initial dephosphorization: dephosphorizing flux is added into a ladle with steel stream during the converter tapping, and the adding amount is between 5 and 20kg / t; 3) deep dephosphorization: the positions of a blanking tube and a descending tube are adjusted to ensure that the descending tube is positioned at the opposite side of the blanking tube, a ladle is transported to a RH station and is pumped into vacuum, compound spheres are added from a RH high-level bin with a circulation for 0.1 to 15min; 4) slag skimming: the vacuum breaking and the slag skimming are performed , and ladle covering flux is added; 5) heating and stirring: the heating and stirring are performed in a refining furnace, and the heating temperature is controlled to between 1,580 and 1,620 DEG C; 6) the deoxidation and the alloying refining treatment are performed; and 7) continuous casting: the continuous casting adopts the whole-process protection.

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