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Production method of low-carbon sulfur series free-cutting steel continuous casting billet

A free-cutting steel and production method technology, applied in the production field of low-carbon sulfur-based free-cutting steel continuous casting slabs, can solve the problems of many hard oxides, fewer continuous casting furnaces, poor castability, etc., and achieve stable composition control , reduced energy consumption, and strong field operability

Inactive Publication Date: 2013-12-25
武汉钢铁有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] The present invention aims at the current problems of long process route, slag rolling, poor castability, steel breakout, few continuous casting furnaces and high content of hard oxides affecting cutting performance in the continuous casting process, and provides a blast furnace molten iron that does not require After desulfurization treatment, the slag is directly loaded into the converter, the continuous casting process is stable, no breakout occurs, the number of continuous casting furnaces is increased, and the quality of the continuous casting billet is continuous casting of low-carbon sulfur-based free-cutting steel with less hard oxide content. billet production method

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] Test conditions: Process: Converter smelting → argon blowing at argon station → continuous casting with arc continuous casting machine, the production section size is 200×200mm 2 , the steps of continuous casting slab of American brand 1215 low-carbon sulfur-based free-cutting steel are as follows:

[0046] 1) Now put the steel scrap into the converter, and then put the molten iron directly into the converter, the ratio of molten iron to steel scrap is controlled at 10:1.5;

[0047] 2) Perform top-bottom compound blowing: before blowing oxygen, supply nitrogen for 2 minutes, and then blow oxygen until the end;

[0048] 3) Tapping: Control the tapping temperature at 1685~1690°C, and the oxygen activity in the steel is 800ppm;

[0049] 4) When tapping reaches 20% of the total amount of molten steel, add 280 kg of Si-Al-Mn alloy according to 0.35 kg / ppm×800ppm (tapping oxygen activity), the chemical composition of Si-Al-Mn alloy and The weight percentage content is: Si: ...

Embodiment 2

[0063] Test conditions: Process: Converter smelting → argon blowing at argon station → continuous casting with arc continuous casting machine, the production section size is 150×150mm 2 , the Japanese brand SUM22 low-carbon sulfur-based free-cutting steel continuous casting steps are as follows:

[0064] 1) Now put the steel scrap into the converter, and then put the molten iron directly into the converter, the ratio of molten iron to steel scrap is controlled at 10:2;

[0065] 2) Perform top-bottom compound blowing: before blowing oxygen, supply nitrogen for 2 minutes, and then blow oxygen until the end;

[0066] 3) Tapping: Control the tapping temperature at 1715~1720°C, and the oxygen activity in the steel is 800ppm;

[0067] 4) When tapping reaches 20% of the total amount of molten steel, add 44.88 kg of Si-Al-Mn alloy according to 0.051 kg / ppm×800ppm (tapping oxygen activity), the chemical composition of Si-Al-Mn alloy and The weight percentage content is: Si: 14%, Al: ...

Embodiment 3

[0081] Test conditions: Process: Converter smelting → argon blowing at argon station → continuous casting with arc continuous casting machine, the production section size is 220×220mm 2 , German brand 11SMn37 low-carbon sulfur-based free-cutting steel continuous casting steps are as follows:

[0082] 1) Now put the steel scrap into the converter, and then put the molten iron directly into the converter, the ratio of molten iron to steel scrap is controlled at 10:3;

[0083] 2) Perform top-bottom compound blowing: before blowing oxygen, supply nitrogen for 2 minutes, and then blow oxygen until the end;

[0084] 3) Tapping: Control the tapping temperature at 1660~1665°C, and the oxygen activity in the steel is 600ppm;

[0085] 4) When tapping reaches 20% of the total amount of molten steel, add 270 kg of Si-Al-Mn alloy according to 0.45 kg / ppm×600ppm (tapping oxygen activity), the chemical composition of Si-Al-Mn alloy and The weight percentage content is: Si: 15%, Al: 14%, Mn...

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Abstract

The invention relates to a production method of a low-carbon sulfur series free-cutting steel continuous casting billet. The method comprises the steps of: first placing scrap steel into a converter, then loading liquid iron into the converter; conducting top-bottom combined blowing; carrying out tapping; performing deoxygenation and alloying; implementing argon blowing treatment; conducting soft argon blowing after alloy fine adjustment; adding carbonized rice hulls into a steel ladle when the argon blowing is over; starting continuous casting when the molten steel temperature reaches 1530-1570DEG C; and employing a continuous casting process of tundish treatment, crystallizer control, secondary cooling, straightening and cutting. The invention has the characteristics that: the smelting is free of desulfurization, LF refining treatment and other processes, no steel breakout phenomenon exists in casting, the composition control is stable, the yields of S and Mn elements are both above 90%, the cutting-tool wear can be reduced during processing so as to improve the service life, the tundish has a high utilization rate, the continuous casting billet has no subcutaneous bubble, heart crack, surface crack and other defects, and is free of composition segregation, and the inclusions in the casting billet are thick, big and in a spherical shape, thus being in favor of shape control of the rolled inclusions and improvement of the steel cutting performance.

Description

technical field [0001] The invention relates to a production method of free-cutting steel, in particular to a production method of continuous casting slabs of low-carbon sulfur series free-cutting steel. Background technique [0002] In recent years, the machinery manufacturing industry has developed towards high speed, precision and automation. In order to reduce cutting processing costs, increase production efficiency, and improve product quality, there is an increasing demand for sulfur-based free-cutting steels with excellent cutting performance. Sulfur-based free-cutting steel is the steel type with the most varieties and the largest output among free-cutting steels today, accounting for about 70% of the total output of free-cutting steel. The sulfur-based free-cutting steel produced in developed countries has been serialized and standardized. Sulfur and sulfur-composite free-cutting steel with cutting performance as the mainstay, the sulfur content is generally between...

Claims

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Application Information

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IPC IPC(8): C22C38/60C22C33/06C21C7/00B22D11/00
Inventor 罗国华范植金朱玉秀王瑞敏徐志东
Owner 武汉钢铁有限公司
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