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Smelting preparation method of high-cleanliness titanium-containing steel

A high cleanliness, titanium steel technology, applied in the smelting field of construction machinery steel, can solve problems affecting product quality and achieve the effect of less TiN inclusions

Inactive Publication Date: 2020-12-29
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] In order to solve the problem of exceeding the standard of B-type inclusions in special steel types, more and more special-purpose steel types choose to use appropriate refining slag systems and deoxidation systems to solve the problem of inclusions in steel, especially Ti-containing steel types such as construction machinery. The representative grade is 35MnB series. The Ti element of this type of steel is easy to combine with the gas element N of the steel type to form large-grained TiN inclusions. The unsuitable cooling system in the continuous casting process will also cause the formation of TiN during the solidification of molten steel. Such inclusions are Participating in the rating of B-type inclusions seriously affects product quality. All iron and steel enterprises are exploring the optimization of TiN inclusions in titanium-containing steels

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] (1) Converter smelting: endpoint control C: 0.08%, P: 0.009%, tapping temperature 1590°C;

[0023] (2) Converter tapping:

[0024] Bottom stirring: Turn on the bottom stirring of the converter before the molten steel is tapped to reduce the oxidation of molten steel and the P content of molten steel;

[0025] Slag removal: slag dumping before tapping the converter, and double-block tapping in the later stage of tapping, no slag removal is serious, and slag removal is not carried out;

[0026] (3) Deoxidation alloying: Add 140kg of aluminum block for deoxidation in the early stage of tapping, and then add alloys (680kg of manganese alloy, 1100kg of silicon-manganese alloy, 410kg of refining slag, 500kg of lime) and slag in sequence. argon;

[0027] (4) LF treatment: control the inclusions in the steel, and the percentage content of the slag in the LF process is 59.61% for CaO and 59.61% for Al 2 o 3 The basicity of the final slag is controlled at 5.28. The power supp...

Embodiment 2

[0031] 1) Converter smelting: endpoint control C: 0.0718%, P: 0.0124%, tapping temperature 1633°C;

[0032] 2) Converter tapping:

[0033] Bottom stirring: Turn on the bottom stirring of the converter before the molten steel is tapped to reduce the oxidation of molten steel and the P content of molten steel;

[0034] Slag removal: slag dumping before tapping the converter, and double-block tapping in the later stage of tapping, no slag removal is serious, and slag removal is not carried out;

[0035] (3) Deoxidation alloying: Add 120kg of aluminum block for deoxidation in the early stage of tapping, and then add alloys (1299kg of manganese alloy, 650kg of silicon-manganese alloy, 382kg of refining slag, 510kg of lime) and slag in sequence. argon;

[0036] (4) LF treatment: control the inclusions in the steel, the percentage of slag in the LF process: CaO is 58.53%, Al 2 o 3 The basicity of the final slag is controlled at 4.89. During the power supply smelting process, deox...

Embodiment 3

[0040] (1) Converter smelting: endpoint control C: 0.0812%, P: 0.0217%, tapping temperature 1631°C;

[0041] (2) Converter tapping:

[0042] Bottom stirring: Turn on the bottom stirring of the converter before the molten steel is tapped to reduce the oxidation of molten steel and the P content of molten steel;

[0043] Slag removal: slag dumping before tapping the converter, and double-block tapping in the later stage of tapping, no slag removal is serious, and slag removal is not carried out;

[0044] (3) Deoxidation alloying: Add 130kg of aluminum block for deoxidation in the early stage of tapping, and then add alloys (1000kg of manganese alloy, 620kg of silicon-manganese alloy, 402kg of refining slag, 500kg of lime) and slag in sequence. argon;

[0045] (4) LF treatment: control inclusions in steel: LF process slag percentage content: CaO is 59.62%, Al 2 o 3 The basicity of the final slag is controlled at 6.17, the power supply smelting process uses silicon carbide and...

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Abstract

The invention discloses a smelting preparation method of high-cleanliness titanium-containing steel. The Ti content of the high-cleanliness titanium-containing steel is above 0.010%. The smelting preparation method comprises the following smelting steps of (1) carrying out converter smelting, (2) carrying out converter tapping, (3) carrying out deoxidation alloying, (4) carrying out LF treatment,(5) carrying out RH treatment, wherein the vacuum degree is controlled to be below 5 mbar, the high vacuum holding time of the vacuum degree below 2.5 mbar is 8-20 min, the mass percentage of N in molten steel is less than or equal to 50ppm, a ferrotitanium wire is fed according to the LF end point residual Ti content to adjust the Ti content, then calcium treatment is conducted, and soft blowingis conducted for above 10 min after calcium treatment; and (6) carrying out continuous casting. According to the smelting preparation method, in order to avoid the situation that TiN is formed due tothe fact that the N content in the molten steel is too high in the refining process, the process is adjusted, a titanium alloy is not added in the LF process to adjust the Ti component, a titanium wire is fed after N removal in RH treatment to adjust the component, and TiN inclusions generated in the steel smelting process are greatly reduced.

Description

technical field [0001] The invention relates to the smelting of construction machinery steels, in particular to a smelting and preparation method for high-cleanness titanium-containing steels. Background technique [0002] In order to solve the problem of exceeding the standard of B-type inclusions in special steel types, more and more special-purpose steel types choose to use appropriate refining slag systems and deoxidation systems to solve the problem of inclusions in steel, especially Ti-containing steel types such as construction machinery. The representative grade is 35MnB series. The Ti element of this type of steel is easy to combine with the gas element N of the steel type to form large-grained TiN inclusions. The unsuitable cooling system in the continuous casting process will also cause the formation of TiN during the solidification of molten steel. Such inclusions are Participating in the rating of B-type inclusions seriously affects product quality, and various ...

Claims

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Application Information

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IPC IPC(8): C21C7/06C21C7/00C21C7/072C21C7/10
CPCC21C7/0006C21C7/06C21C7/072C21C7/10
Inventor 周杨胡志勇李林翟卫江许旭东李天学刘义唐前进鲁川韦士琨周士北殷天颖赵治国
Owner NANJING IRON & STEEL CO LTD
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