Refining method for reducing inclusions in steel for steel cord

A technology for inclusions and steel cords, applied in the refining field of reducing inclusions in steel for steel cords, can solve problems such as insufficient capacity, high strength, incomplete deoxidation, etc., and achieve the effect of reducing inclusions

Inactive Publication Date: 2013-09-25
JIANGSU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002]Steel for steel cord is a high-quality hard steel product, and also one of the highest strength steel types in commercial steel. Due to the production process of steel cord, the Wire rods with a diameter of 5-8mm are drawn into filaments with a diameter of 0.1-0.2mm, and the filaments need to be twisted, which requires high strength and does not allow broken filaments; therefore, it is required to have a very high degree of cleanliness, especially for The requirements for inclusions in steel are the highest, and inclusions > 30 microns are not allowed, especially for brittle Al2O3 and calcium aluminate inclusions. Exist; the existing technology to reduce the inclusions in the steel is mainly that the steel used for the steel cord cannot be deoxidized by Al, the acid slag produced by refining outside the furnace absorbs the aluminum-calcium inclusions, and the time of argon blowing is increased; the existing technology produces steel curtain For wire steel, the main problem is the removal and control of deoxidation and oxide inclusions during refining outside the furnace. Since the cord steel cannot be deoxidized with Al, the deoxidation with silicon and manganese is not complete, resulting in more oxide inclusions in the steel. , because in order to make the top slag in the ladle have a higher ability to absorb Al2O3, the LF refining process produces acid slag, which causes the top slag to absorb silicon deoxidation product SiO2 is insufficient, so the current steel for steel cord often has silicate inclusions, which has become one of the main factors affecting the performance of steel cord

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Using 100 tons of converter for smelting, the amount of scrap steel added is 10%, the amount of molten iron added is 90%, the sulfur content in the molten iron is 0.030%, and the steel composition at the end of smelting is: carbon content 0.50%, phosphorus content 0.008%, sulfur content 0.012%, titanium 0.004 %, the tapping temperature is 1630°C, during the tapping process, when the tapping amount reaches half, pre-deoxidize and alloy with ferromanganese and ferrosilicon, adjust the composition of molten steel in the ladle to silicon: 0.20%, manganese: 0.55%, and Add ladle slag reducing agent and pre-melted top slag to the ladle when the amount of steel tapping reaches three-quarters. The ladle slag reducing agent is 300kg calcium carbide, and the sum of iron oxide and manganese oxide content in the ladle top slag is controlled to be less than 1%. The slag is pre-melted with 80% lime-20% boron anhydride, and the addition amount is 1t. During the process from tapping out ...

Embodiment 2

[0019] Using 80 tons of converter for smelting, the amount of scrap steel added is 10%, the amount of molten iron added is 90%, the sulfur content in the molten iron is 0.030%, and the steel composition at the end of smelting is: carbon content 0.20%, phosphorus content 0.008%, sulfur content 0.013%, titanium 0.004 %, the tapping temperature is 1640°C, during the tapping process, when the tapping amount reaches half, pre-deoxidize and alloy with ferromanganese and ferrosilicon, adjust the composition of molten steel in the ladle to silicon: 0.15%, manganese: 0.50%, and Add ladle slag reducing agent and pre-melted top slag to the ladle when the amount of steel tapping reaches 3 / 4. The slag is pre-melted with 60% lime-40% boron anhydride, and the addition amount is 0.8t. During the process from tapping out of the smelting furnace to LF exiting the station, the molten steel in the ladle is blown with argon at a pressure of 0.45MPa. , promote the floating of inclusions, use carbon...

Embodiment 3

[0021] Using 200 tons of converter for smelting, the amount of scrap added is 12%, the amount of molten iron added is 88%, the sulfur content in the molten iron is 0.030%, and the steel composition at the end of smelting is: carbon content 0.45%, phosphorus content 0.008%, sulfur content 0.013%, titanium 0.004 %, the tapping temperature is 1630°C, during the tapping process, when the tapping amount reaches half, pre-deoxidize and alloy with ferromanganese and ferrosilicon, adjust the composition of molten steel in the ladle to silicon: 0.18%, manganese: 0.55%, and Add ladle slag reducing agent and pre-melted top slag to the ladle when the amount of steel tapping reaches 3 / 4. The slag is pre-melted with 70% lime-30% boron anhydride, and the addition amount is 2t. During the process from the tapping of the smelting furnace to the exit of the LF, the molten steel in the ladle is blown with argon at a pressure of 0.45MPa. Promote the floating of inclusions; use carbon powder as a ...

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Abstract

The invention provides a refining method for reducing inclusions in steel for steel cord. The refining method provided by the invention is characterized in that converter or electric furnace smelting tapping control elements comprise: by weight, 0.20-0.50% of carbon content, less than 0.01% of phosphorus content, less than 0.02% of sulfur content and less than 0.005% of titanium; during the tapping process, pre-deoxidation and alloying are carried out by the use of manganese and silicon alloys, powdered carbon is used as a carburant, a steel ladle slag reducing agent and premelting top slag are added in steel ladle, calcium carbide or silicon carbide are used as the steel ladle slag reducing agent, and the premelting slag is formed by premelting lime-boron oxide; deep deoxidation and desulphurization are carried out by the use of silico-calcium or silico-calcium-barium alloy during the LF refining process, the content of Al2O3 is controlled to be less than 5%, and from tapping in the smelting furnace to LF outbound, argon blowing is carried out on molten steel in ladle in the whole course to promote inclusions to float. By the adoption of the refining method provided by the invention, it is beneficial to remove oxide inclusions, sulfide inclusions, titanium inclusions and the like in steel for steel cord and raise performance of steel cord, cost is reduced, and resources are saved.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgical production, and in particular relates to a refining method for reducing inclusions in steel for steel cords. Background technique [0002] The steel for steel cord is a high-quality hard wire steel, and it is also one of the steel types with the highest strength in commercial steel. During the production process of steel cord, the wire rod with a diameter of 5-8mm should be drawn into a wire rod with a diameter of 0.1-0.2mm. Filaments, and filaments also need to be twisted, require high strength, and broken filaments are not allowed; therefore, it is required to have a very high degree of cleanliness, especially the highest requirements for inclusions in steel, and inclusions > 30 microns are not allowed substances exist, especially for brittle Al 2 o 3 and calcium aluminate inclusions are not allowed to exist; the current existing technologies for reducing inclusions in steel are ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C7/06C21C7/064
Inventor 王宏明李桂荣
Owner JIANGSU UNIV
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