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Method for manufacturing high-quality SCr420 HB automobile gear steel

A manufacturing method and scr420hb technology, applied in the field of metal material manufacturing, can solve the problems of steel surface quality, composition segregation, affecting surface quality, etc., and achieve the effect of reducing the fluctuation of quenching hardness and reducing composition segregation

Active Publication Date: 2013-10-16
FUSHUN SPECIAL STEEL SHARES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In order to ensure the safety and stability of its products, Hyundai Motor Company has put forward stricter requirements on material quality and technical indicators. In order to reduce heat treatment deformation, wear and noise of gears, the hardenability bandwidth is only 30% of normal steel grades. Only 3HRC; high cleanliness requirements, oxygen content ≤ 15ppm, inclusions are inspected according to the Japanese standard JIS G0555, dB+dC ≤ 0.05%; strict surface quality requirements, suitable for precision forging requirements, no domestic and foreign literature reports related Valuable smelting, processing technology information and hardenability research information; Fushun Special Steel Co., Ltd. is the only manufacturer of SCr420HB steel in China, and the product specifications are ∮20mm~∮90mm
The continuous casting and rolling process is adopted, and the continuous casting slab is directly formed into a material, which is easy to cause composition segregation and steel surface quality problems, and it is difficult to achieve the technical requirement that the hardenability bandwidth is not greater than 3HRC. In production, the hardenability exceeds the specified range and is often found in batches. Qualified steel; because SCr420HB steel contains B and Nb elements, it is easy to form carbon and nitride, resulting in poor surface quality of the billet, affecting the surface quality of finished products, causing surface defects in the forging process of steel parts, and often surface quality objections

Method used

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  • Method for manufacturing high-quality SCr420 HB automobile gear steel
  • Method for manufacturing high-quality SCr420 HB automobile gear steel
  • Method for manufacturing high-quality SCr420 HB automobile gear steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0061] Steel specification: φ30mm, processing ratio 81.5;

[0062] The technological process adopted is: 60-ton ultra-high power electric furnace → LF → VD → continuous casting → continuous furnace heating → continuous rolling mill rolling → finishing → straightening and chamfering → surface eddy current flaw detection → packaging;

[0063] (1) The charging capacity of the electric furnace is 68 tons, and the furnace materials are scrap steel and pig iron, of which the amount of scrap steel is 38 tons, and the amount of pig iron is 30 tons; the tapping temperature is 1665°C, the P content is 0.013%, the end carbon is 0.10%, and 3 minutes before tapping Reduce the intensity of oxygen consumption, and the amount of carbon injection is 350kg; add 60kg of aluminum for final deoxidation, 100 kg of calcium carbide; 900kg of lime, 100kg of pre-melted slag, and no oxidation slag;

[0064] ⑵The LF furnace is in place to feed the aluminum wire 300m, the whole process uses SiC powder + A...

Embodiment 2

[0082] Steel specification: φ45mm, processing ratio 36.2;

[0083] The technological process adopted is: 60-ton ultra-high power electric furnace → LF → VD → continuous casting → continuous furnace heating → continuous rolling mill rolling → finishing → straightening and chamfering → surface eddy current flaw detection → packaging;

[0084] (1) The charging capacity of the electric furnace is 65 tons, and the furnace materials are scrap steel and pig iron, of which the amount of scrap steel is 35 tons, and the amount of pig iron is 30 tons; the tapping temperature is 1670 ° C, the P content is 0.010%, the end point carbon is 0.12%, and 3 minutes before tapping Reduce the intensity of oxygen consumption, and the amount of carbon injection is 400kg; add 60kg of aluminum for final deoxidation, 100 kg of calcium carbide; 1000kg of lime, 100kg of pre-melted slag, and no oxidation slag;

[0085] ⑵The LF furnace feeds 300m of aluminum wire in place, and adopts SiC powder + Al particl...

Embodiment 3

[0099] Steel specification: φ60mm, processing ratio 20.3;

[0100] The technological process adopted is: 60-ton ultra-high power electric furnace → LF → VD → continuous casting → continuous furnace heating → continuous rolling mill rolling → finishing → straightening and chamfering → surface eddy current flaw detection → packaging;

[0101] (1) The charging capacity of the electric furnace is 65 tons, and the furnace materials are scrap steel and pig iron, of which the amount of scrap steel is 25 tons, and the amount of pig iron is 40 tons; the tapping temperature is 1668°C, the P content is 0.010%, the end carbon is 0.10%, and 3 minutes before tapping Reduce the intensity of oxygen consumption, and the amount of carbon injection is 400kg; add 60kg of aluminum for final deoxidation, 100 kg of calcium carbide; 1185kg of lime, 100kg of pre-melted slag, and no oxidation slag;

[0102] ⑵The LF furnace feeds 300m of aluminum wire in place, and uses SiC powder + Al particle diffusio...

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Abstract

The invention discloses a method for manufacturing high-quality SCr420 HB automobile gear steel. The method aims at reducing the oxygen content and occluded foreign substances in the steel, guaranteeing the stability of the quenching degree and guaranteeing the high quality of the surface of the steel. The method includes the process routes of using an ultra high power electric furnace, conducting LF, conducting VD, conducting continuous casting, continuously heating through the ultra high power electric furnace, conducting rolling through a continuous rolling mill, conducting finishing, conducting straightening and chamfering, conducting surface eddy current testing and packaging. The continuous casting in the steelmaking process adopts long nozzle protection, casting powder and argon shielding pouring, internal control compositions are appropriately designed, the N element content in the steel is controlled, and the form of the B element in the steel is controlled. The superheat degree and the casting speed in the continuous casting are controlled. The method has the advantages of reducing the oxygen content and the occluded foreign substances in the steel, enabling the gas oxygen content in the steel to be less than 15ppm, and enabling the non-metallic inclusion completely to meet the Korea modern standards, controlling the close limit of the chemical element, guaranteeing the quenching degree, guaranteeing the high quality of the surface of the steel, and meeting the precision forging requirement.

Description

technical field [0001] The invention belongs to the field of metal material manufacturing and discloses a method for manufacturing high-quality automobile gear steel, which is mainly used for the production of alloy structural steel SCr420HB steel. Background technique [0002] SCr420HB is a Korean brand. It is based on the Japanese brand SCr420H steel to increase the control content of Mn elements, and additional B and Nb elements are added. It is widely used in the manufacture of Hyundai automobile transmission gears in South Korea. In order to ensure the safety and stability of its products, Hyundai Motor Company has put forward stricter requirements on material quality and technical indicators. In order to reduce heat treatment deformation, wear and noise of gears, the hardenability bandwidth is only 30% of normal steel grades. Only 3HRC; high cleanliness requirements, oxygen content ≤ 15ppm, inclusions are inspected according to the Japanese standard JIS G0555, dB+dC ≤ ...

Claims

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Application Information

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IPC IPC(8): B22D11/18B22D11/16C21C5/52
CPCY02P10/20
Inventor 王志才冯桂萍李涛刘金鑫陈庆新王海江马群赵敏薛井恒穆立峰赵成志顾文涛赵志刚
Owner FUSHUN SPECIAL STEEL SHARES
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