A nitrogen control method for carburized gear steel

A gear steel and carburizing technology, applied in the field of metallurgy, can solve the problems of low yield, great influence on the purity of molten steel, instability, etc., to achieve uniform composition, promote inclusions to float, and reduce decomposition.

Active Publication Date: 2021-06-18
SHIJIAZHUANG IRON & STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, when manganese nitride is added during the alloying process of converter tapping, due to the high oxygen content in molten steel and the high temperature of molten steel, the manganese nitride alloy is easily decomposed, and the yield is low and unstable; while in VD vacuum Feeding manganese nitride cored wire into molten steel after refining has a great influence on the purity of molten steel

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] The nitrogen control method of carburized gear steel in this embodiment includes converter smelting, LF ladle refining, VD vacuum refining, and continuous casting processes. The specific process steps are as follows:

[0023] (1) Converter smelting: After the converter is tapped, the molten steel in the ladle is soft blown for 2 minutes at a flow rate of 80NL / min, and manganese nitride alloy (nitrogen content: 4.5%) is added to the molten steel during the soft blowing process;

[0024] (2) Refining of LF ladle: During the refining process of LF ladle, when the temperature of molten steel reaches 1560°C, nitrogen gas is blown into the molten steel by ladle bottom blowing. The nitrogen pressure is 0.6MPa and the flow rate is 300NL / min. The time is 10 minutes;

[0025] (3) VD vacuum refining: when the vacuum degree of VD vacuum refining is 65Pa, the ladle starts to blow argon gas at the bottom, the pressure of argon gas is 0.2MPa, the flow rate is 15NL / min, the argon gas i...

Embodiment 2

[0030] The nitrogen control method of carburized gear steel in this embodiment includes converter smelting, LF ladle refining, VD vacuum refining, and continuous casting processes. The specific process steps are as follows:

[0031] (1) Converter smelting: After the converter is tapped, the molten steel in the ladle is soft blown for 3 minutes at a flow rate of 110NL / min, and manganese nitride alloy (nitrogen content: 5%) is added to the molten steel during the soft blowing process;

[0032] (2) Refining of LF ladle: During the refining process of LF ladle, when the temperature of molten steel reaches 1555°C, nitrogen gas is blown into molten steel by ladle bottom blowing. The pressure of nitrogen is 1.0MPa and the flow rate is 500NL / min. The time is 12 minutes;

[0033] (3) VD vacuum refining: When the vacuum degree of VD vacuum refining is 63Pa, the ladle starts to blow argon gas at the bottom, the pressure of argon gas is 0.4MPa, the flow rate is 25NL / min, the argon gas is ...

Embodiment 3

[0038] The nitrogen control method of carburized gear steel in this embodiment includes converter smelting, LF ladle refining, VD vacuum refining, and continuous casting processes. The specific process steps are as follows:

[0039] (1) Converter smelting: After the converter is tapped, the molten steel in the ladle is soft blown for 3 minutes at a flow rate of 90NL / min, and manganese nitride alloy (nitrogen content: 4.8%) is added to the molten steel during the soft blowing process;

[0040] (2) Refining of LF ladle: During the refining process of LF ladle, when the temperature of molten steel reaches 1565°C, nitrogen gas is blown into the molten steel by ladle bottom blowing. The nitrogen pressure is 0.8MPa and the flow rate is 400NL / min. The time is 11 minutes;

[0041] (3) VD vacuum refining: When the vacuum degree of VD vacuum refining is 64Pa, the ladle starts to blow argon gas at the bottom, the pressure of argon gas is 0.3MPa, the flow rate is 20NL / min, and the argon g...

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Abstract

The invention discloses a nitrogen control method for carburizing gear steel. The nitrogen control method comprises the steps of converter smelting, LF ladle refining, VD vacuum refining and continuous casting. In the present invention, the molten steel in the ladle is softly blown after the converter is tapped, the manganese nitride alloy is added to the molten steel during the soft blowing process, and nitrogen is blown into the molten steel during the refining process of the LF ladle, so as to effectively improve the content of the molten steel in the molten steel. Nitrogen content; degassing and de-inclusion during VD vacuum refining. The nitrogen control method of the carburized gear steel of the present invention can realize precise control of the nitrogen content in the carburized gear steel, so as to have a better effect of refining grains. The high cleanliness of the carburized gear steel is realized, and the cleanliness requirements are met; the nitrogen control method of the present invention can be realized by simply improving the preparation process of the existing carburized gear steel, and has the advantages of low cost of process improvement and easy popularization. Advantage.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a nitrogen control method for carburized gear steel. Background technique [0002] Gear steel is one of the key materials with high requirements among special alloy steels used in automobiles, railways, ships, and construction machinery, and is a manufacturing material for core components that ensure safety. The commonly used steel types for gear steel include quenched and tempered steel, quenched steel, and carburized steel, etc., which have high strength, high wear resistance, and can resist impact. Among them, carburized gear steel is widely used because of its better grain size and better comprehensive performance. [0003] Carburized gear steel has strict requirements on grain size. Usually, by increasing the content of fine-grained elements Al and N in the steel, Al≥0.030%, N≥0.0110%, so that the steel can be heated at a high heating rate and kept at a high ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21C7/00C21C7/072C21C7/10C22C38/02C22C38/04C22C38/06C22C38/22C22C38/44
CPCC21C7/0006C21C7/072C21C7/10C22C38/001C22C38/002C22C38/02C22C38/04C22C38/06C22C38/22C22C38/44
Inventor 李世琪李建业刘勇容晨光张红卫高鹏秦影
Owner SHIJIAZHUANG IRON & STEEL
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