CN101363068A

CN101363068A - Smelting method of low-phosphorus steel

Info

Publication number: CN101363068A
Application number: CNA2008102232544A
Authority: CN
Inventors: 许晓东; 朱志远; 王文军; 吕延春; 王浩然; 姜中行; 麻庆申; 刘金刚; 郝宁; 石磊
Original assignee: Shougang Corp
Current assignee: Shougang Group Co Ltd
Priority date: 2008-09-28
Filing date: 2008-09-28
Publication date: 2009-02-11
Anticipated expiration: 2028-09-28
Also published as: CN101363068B

Abstract

A smelting process of low-phosphorus molten steel by a low-carbon steel converter belongs to the technical field of converter steelmaking of the metallurgical industry. The process is as follows: smelting of low-carbon and low-phosphorus molten steel is realized by controlling amounts of molten iron, scrap steel, slag formers of the primary slag and the secondary slag, and the like, in the converter and by controlling bottom blowing, carbon drawing and end points. The weight percentages of the molten iron and the scrap steel in the metal charges which are put into the converter are respectively 82%-86% and 14%-18%, and the alkalinity of the primary slag and the secondary slag are respectively controlled at 1.8-2.2 and 4.0-5.0, the temperature of the molten steel is controlled at 1320-1370 DEG C when making the primary slag, the temperature of the molten steel is controlled at 1650-1670 DEG C when drawing the carbon, the carbon content of the molten steel is 0.035-0.045%, the carbon content at the reblowing end point of the converter is 0.02 -0.04%, and the phosphorus content of the molten steel is controlled below 50ppm.

Description

A kind of smelting method of low-phosphorus steel

Technical field

The invention belongs to metallurgy industry converter steeling technology field, a kind of smelting method of low-phosphorus steel particularly is provided, at the smelting method of low-phosphorus steel of soft steel.

Background technology

Over past ten years, the user increases greatly to the demand that high tensile steel particularly hangs down phosphoretic steel, as high-grade pipe line steel, oil well pipe steel etc., these high trade mark products have proposed very high requirement to phosphorus content in the steel, because phosphorus is a kind of easy segregation element in steel, especially when phosphorus content in the steel greater than 0.015% the time, the segregation of phosphorus sharply increases, thus influence the welding property of steel, significantly reduce steel low-temperature impact toughness, improve the brittle transition temperature of steel.There are some researches show that when phosphorus content in the steel was increased to 150ppm by 60ppm, the steel low-temperature impact toughness can reduce by 40%.

Conventional converter process is difficult to the requirement that realizes that molten steel is low-phosphorous, has therefore developed various dephosphorization technology both at home and abroad in succession, as Technologies such as the pre-dephosphorization of molten iron, converter double slag process, converter duplex methods.Dephosphorizing method can be divided into two classes at present, one class is to carry out dephosphorization in hot metal ladle or torpedo tank car, this technology is owing to a large amount of silicon in the hot metal pretreatment process is removed, so limited the add-on of steel scrap in the converter, this method is adopted in Japanese iron and steel enterprise on a large scale.Another kind of dephosphorizing method is to carry out dephosphorization in converter, comprises converter double slag process dephosphorizing technology and converter duplex smelting technology.Wherein the former (as patent documentation CN94192953.1 and JP7179921) utilizes the converter initial stage to help the characteristics of dephosphorization, carrying out decarburization after dephosphorized slag outwelled again smelts, its advantage is only to need single converter can realize the smelting of low phosphorus and low carbon molten steel, adopt this technology can produce high-quality low phosphoretic steel, but its shortcoming is that the converter smelting time is long and be difficult to realize optimum matching with continuous casting working procedure; And be to adopt two block converter duplex operations by the converter duplex smelting technology (as patent documentation JP1024517, JP11193413 and JP11193414) that Japan exploitation, Baosteel being are are being researched and developed, one is carried out the dephosphorization of molten iron operation, be called the dephosphorization stove, another block converter is accepted to carry out the decarburization operation from the low-phosphorous molten iron of dephosphorization stove, is called the decarburization stove.The advantage of the low production of phosphorus of this duplex is that dephosphorisation reaction speed is fast, efficient is high, help producing ultra-low phosphoretic steel, but duplex dephosphorized technology is higher to the arrangement requirement between production cycle and converter.

Summary of the invention

The object of the present invention is to provide a kind of smelting method of low-phosphorus steel, at the two slag smelting method of low-phosphorus steel of the converter of soft steel, to satisfy high-quality pipe line steel, High Strength Construction Steel, low-temperature (low temperature) vessel with the low-phosphorous composition requirement of soft steel such as steel.

The blowing that smelting process of the present invention adopts, slag making, the CONTROL PROCESS of catch carbon and terminal point is: converter is gone into the stove molten iron silicon content 0.40-0.60%, go in the stove metal charge molten iron and steel scrap weight proportion respectively 82-86% and 14-18%, lime and light dolomite add-on are respectively into 3.0-4.5% and 1.6-2.0% of stove metal charge weight when making head batch slag, basicity of slag is controlled at 1.8-2.2, liquid steel temperature is controlled at 1320-1370 ℃, after head is criticized 4-5 minutes time of slag slag making, remove 50% slag, go into the lime of stove metal charge weight 3.0-4.5% afterwards once more.Two batches of basicity of slag are controlled at 4.0-5.0, and blowing argon bottom-blowing flow in latter stage remains on 500-600m ³/ h, 0.035-0.045%, the rear converter endpoint molten steel carbon content of re-blowing can be controlled in 0.02-0.04% to the control liquid steel temperature at 1650-1670 ℃, carbon content of molten steel, phosphorus content can be controlled to≤50ppm during catch carbon.

Advantage of present method and effect:

1. deep dephosphorization is to guarantee to adopt double slag process to realize under the low endpoint carbon content condition, and blowing, slag making, catch carbon and the end point controlling process parameter of the present invention's design make the converter terminal carbon content between 0.02-0.04%, end phosphorus content≤50ppm.

2. the design on the feed stock for blast furnace proportioning that present method adopted, add-on, adding opportunity makes converter steelmaking process be easy to control more, and end point carbon and phosphorus content reach desired scope easily.

Embodiment

Embodiment 1:

100 tons of top and bottom combined blown converters of certain factory adopt this technology to smelt X70 pipe line steel, converter process control parameters such as following table 1.Converter terminal carbon content and phosphorus content are respectively: 0.030% and 40ppm.

The major equipment parameter of converter: furnace shell external diameter 5750mm, overall height 8390mm, aspect ratio: 1.46, the heat size ratio: 0.83, pool depth: about 1100mm.

Table 1 X70 pipe line steel converter process control parameters and end phosphorus content

Embodiment 2: 100 tons of top and bottom combined blown converters of certain factory adopt this technology to smelt X80 pipe line steel, converter process control parameters such as following table 2.Converter terminal carbon content and phosphorus content are respectively: 0.025% and 40ppm.

Table 2 X80 pipe line steel converter process control parameters and end phosphorus content

Claims

1, a kind of converter smelting method of low-phosphorus steel, it is characterized in that: converter is gone in the stove metal charge molten iron and steel scrap weight proportion respectively 82%-86% and 14%-18%, molten iron silicon content is 0.40-0.60%, utilize two slag methods, liquid steel temperature is controlled at 1320-1370 ℃ when making head batch slag, and liquid steel temperature is controlled at 1650-1670 ℃ during catch carbon.

2, method according to claim 1, it is characterized in that, lime and light dolomite add-on are respectively into 3.0-4.5% and 1.6-2.0% of stove metal charge weight when making head batch slag, basicity of slag is controlled at 1.8-2.2, after criticizing 4-5 minutes time of slag slag making, removes on head 50% slag, the amount of lime that adds once more is to control basicity 4.0-5.0 into 3.0-4.5%, two batches of slags of stove metal charge weight afterwards.

3, method according to claim 1 is characterized in that, carbon content of molten steel is controlled at 0.035-0.045% during catch carbon, the rear converter endpoint molten steel carbon content of re-blowing 0.02-0.04%, the molten steel phosphorus content is below 50ppm.