Smelting method of high-nitrogen sulfur-containing free-cutting steel

A technology of free-cutting steel and smelting methods, which is applied to the improvement of process efficiency and the manufacture of converters, etc. It can solve the problems of difficult control of nitrogen and sulfur content, unfavorable mass production, low purity of molten steel, etc., and achieve a stable refining cycle , Guarantee the rhythm of production and improve the purity of molten steel

Inactive Publication Date: 2020-11-03
WUHAN IRON & STEEL GRP ECHENG IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is: in the production process of high-nitrogen and sulfur-containing free-cutting steel in the prior art, it is difficult to control the content of nitrogen and sulfur, the operation is cumbersome, and the purity of molten steel is low, which is not conducive to the control of inclusions and large-scale production. To solve production problems, a method for smelting high-nitrogen and sulfur-containing free-cutting steel is provided; the method of the present invention is simple and effective, easy to operate, can precisely control the refining time and refining composition, improve the quality of molten steel, ensure the production rhythm, and ensure a narrow range of molten steel components Precise control to achieve mass and stable production of high-nitrogen and sulfur-containing free-cutting steel

Method used

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] The smelting method of free-cutting steel in this embodiment mainly includes: converter smelting and tapping → LF refining furnace → RH vacuum furnace → continuous casting, especially:

[0030] (1) Converter smelting and tapping

[0031] ①Molten iron and steel scrap are used as raw materials for smelting in a converter, wherein the mass fraction of molten iron is 81% of the raw material, and the mass fraction of scrap steel is 19%. Control C: 0.12%, P: 0.023%, tapping temperature is 1595°C, and slide plate is used to stop slag;

[0032] ② Add aluminum ingots to molten steel during the tapping process. The amount of aluminum ingots added is 2.2kg / t, and then add ferrosilicon, silicon manganese, ferrochromium and ferrovanadium to molten steel to adjust the content of Si in molten steel to 0.65%, Mn The content of Cr is 1.00%, the content of Cr is 0.17%, and the content of V is 0.19%;

[0033] (2) LF refining furnace

[0034] ① The refining furnace produces low-basic sl...

Embodiment 2

[0045] The smelting method of free-cutting steel in this embodiment mainly includes: converter smelting and tapping → LF refining furnace → RH vacuum furnace → continuous casting, especially:

[0046] (1) Converter smelting and tapping

[0047] ①Molten iron and steel scrap are used as raw materials for smelting in a converter, wherein the mass fraction of molten iron is 80% of the raw material, and the mass fraction of scrap steel is 20%. Control C: 0.15%, P: 0.026%, tapping temperature is 1590°C, and slide plate is used to stop slag;

[0048] ② Add aluminum ingots to molten steel during the tapping process, the amount of aluminum ingots added is 2.3kg / t, and then add ferrosilicon, silicon manganese, ferrochrome and ferrovanadium to molten steel to adjust the content of Si in molten steel to 0.65%, Mn The content of Cr is 0.98%, the content of Cr is 0.15%, and the content of V is 0.19%;

[0049] (2) LF refining furnace

[0050] ① The refining furnace produces low-basicity s...

Embodiment 3

[0061] The smelting method of free-cutting steel in this embodiment mainly includes: converter smelting and tapping → LF refining furnace → RH vacuum furnace → continuous casting, especially:

[0062] (1) Converter smelting and tapping

[0063] ①Molten iron and steel scrap are used as raw materials for smelting in a converter. The mass fraction of molten iron in the raw material is 85%, and the mass fraction of scrap steel in the raw material is 15%. During smelting, the temperature of the molten iron is controlled at 1370°C, P: 0.110%; at the end of smelting Control C: 0.16%, P: 0.026%, the tapping temperature is 1585°C, and slide plate is used to stop slag;

[0064] ② Add aluminum ingots to the molten steel during the tapping process. The amount of aluminum ingots added is 2.2kg / t, and then add ferrosilicon, silicon manganese, ferrochrome and ferrovanadium to the molten steel to adjust the content of Si in molten steel to 0.68%, Mn The content of Cr is 1.01%, the content of...

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Abstract

The invention discloses a smelting method of high-nitrogen sulfur-containing free-cutting steel. The smelting method mainly comprises the following steps of converter smelting tapping, LF refining furnace treatment, RH vacuum furnace treatment and continuous casting; an aluminum ingot is added in the tapping process for pre-deoxidation, low-alkalinity slag is made by an LF refining furnace, a small amount of aluminum particles are added in the slag surface, the diffusion deoxidation efficiency is improved, and molten steel is greatly purified; and an RH vacuum furnace adopts nitrogen drive, limit vacuum is kept for a certain time, a first-stage pump is retreated to a fourth-stage pump after vacuum breaking, a nitrogen-containing alloy is added, and circulation is conducted for 5 min, so that the S content and the N content in the steel can be accurately controlled, narrow-range accurate control over molten steel components is guaranteed, meanwhile, the refining period is stabilized, operation is easy, and the method is suitable for mass production. The method is simple, effective, easy to operate, capable of accurately controlling refining time and refining components, improving molten steel quality and guaranteeing the production rhythm and suitable for wide popularization.

Description

technical field [0001] The invention belongs to the technical field of free-cutting steel manufacturing, and in particular relates to a method for smelting high-nitrogen and sulfur-containing free-cutting steel. Background technique [0002] When many domestic manufacturers produce high-nitrogen and sulfur-containing free-cutting steel, the LF refining furnace uses high-basicity slag, which has a great influence on the S content in the steel, especially the S yield will be affected Large impact, not easy to stabilize S narrow range control. However, the N in the steel is at a low level after the RH vacuum treatment. In the later stage, a large amount of nitrogen-containing alloy or cored wire needs to be added, and the large bottom blowing is used to stir the alloy to help melt the alloy. The temperature drop is relatively large, and it is easy to cause secondary oxidation of the molten steel. [0003] In "Modern Metallurgy", there is a paper titled "Narrow Composition Cont...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/24C22C38/06C22C38/22C22C38/44C22C38/46C22C38/60C22C33/06C21C5/28C21C7/06C21C7/00C21C7/10
CPCC22C38/02C22C38/04C22C38/24C22C38/06C22C38/22C22C38/44C22C38/46C22C38/60C22C38/001C22C33/06C21C5/28C21C7/06C21C7/0087C21C7/10C21C7/0006Y02P10/20
Inventor 张渊普杜方汪菊华陈华强万升陈曦孙晶黄海玲
Owner WUHAN IRON & STEEL GRP ECHENG IRON & STEEL CO LTD
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