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Production method of low-phosphorous-content gear steel for automobile gearbox

A technology of automobile gearbox and production method, which is applied in the field of metallurgy, can solve the problems of large hardenability bandwidth, unstable composition, and high phosphorus content in gear steel for automobile gearbox, so as to reduce the hardenability bandwidth and strengthen the casting process Control and improve the effect of billet segregation

Active Publication Date: 2019-09-13
HANDAN IRON & STEEL GROUP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] The technical problem to be solved by the present invention is to provide a production method of low-phosphorus gear steel for automobile gearboxes, which can effectively solve technical problems such as high phosphorus content, unstable composition, and wide hardenability bandwidth of the gear steel for automobile gearboxes. , the hot-rolled bars produced can be directly used to process gears for high-quality automotive transmissions

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] The specification of the low-phosphorus gear steel bar for the automobile gearbox in this embodiment is φ35mm, and its production method comprises the following steps:

[0042] (1) After initial smelting in converter, LF refining, RH refining, and continuous casting process, a qualified steel slab is made. The size of the end face of the slab is 200mm*200mm. The chemical composition and mass percentage of the slab are: C: 0.18wt%, Si: 0.22wt%, Mn: 0.9wt%, P: 0.010wt%, S: 0.006wt%, Cr: 1.10wt%, Ti: 0.05wt%, Als: 0.023wt%, Ni: 0.02wt%, Cu: 0.01wt%, Mo: 0.001wt%, the rest is iron and unavoidable impurity elements; the primary smelting of the converter adopts double slag smelting, the control end point P: 0.007wt%, and the aluminum-containing modifier with a basicity of 7.3 is added to the tapping process. The ladle slag is modified, and the (FeO) content in the ladle slag is reduced to 1.3wt%; LF adopts a composite deoxidation process, and the binary basicity of the final ...

Embodiment 2

[0048] The specification of the low-phosphorus gear steel bar for the automobile transmission of this embodiment is φ45mm, and its production method comprises the following steps:

[0049] (1) After initial smelting in converter, LF refining, RH refining, and continuous casting process, a qualified steel slab is made. The size of the end face of the slab is 200mm*200mm. The chemical composition and mass percentage of the slab are: C: 0.19wt%, Si: 0.24wt%, Mn: 0.96wt%, P: 0.012wt%, S: 0.005wt%, Cr: 1.11wt%, Ti: 0.06wt%, Als: 0.028wt%, Ni: 0.01wt%, Cu: 0.01wt%, Mo: 0.002wt%, the rest is iron and unavoidable impurity elements; the primary smelting of the converter adopts double slag smelting, the control end point P: 0.008wt%, and the aluminum-containing modifier with a basicity of 7.3 is added to the tapping process. The ladle slag is modified, and the (FeO) content in the ladle slag is reduced to 1.5wt%; LF adopts a composite deoxidation process, and the binary basicity of the ...

Embodiment 3

[0055] The specification of the low-phosphorus gear steel bar for the automobile gearbox in this embodiment is φ50mm, and its production method comprises the following steps:

[0056] (1) After initial smelting in converter, LF refining, RH refining, and continuous casting process, a qualified steel slab is made. The size of the end face of the slab is 200mm*200mm. The chemical composition and mass percentage of the slab are: C: 0.19wt%, Si: 0.21wt%, Mn: 0.94wt%, P: 0.010wt%, S: 0.003wt%, Cr: 1.12wt%, Ti: 0.06wt%, Als: 0.029wt%, Ni: 0.01wt%, Cu: 0.01wt%, Mo: 0.001wt%, the rest is iron and unavoidable impurity elements; the primary smelting of the converter adopts double slag smelting, the control end point P: 0.007wt%, and the aluminum-containing modifier with a basicity of 7.6 is added to the tapping process. The ladle slag is modified, and the (FeO) content in the ladle slag is reduced to 1.2wt%; LF adopts a composite deoxidation process, and the binary basicity of the final...

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PUM

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Abstract

The invention relates to a production method of low-phosphorous-content gear steel for an automobile gearbox. The production method comprises the process flow including converter smelting, LF+RH refining, continuous casting, hot rolling and rolling. According to a converter technology, dual-drag smelting is adopted, steel ladle slag is improved while the quantity of slag discharged out of a largeladle is decreased, and the content of FeO in large ladle slag is controlled to be equal to or lower than 1.5wt%. According to the LF refining working step, final slag is subjected to refining operation with the high alkalinity and the low calcium-to-aluminum ratio, and in the process, aluminum wire making precipitation deoxidation is used in cooperation with slag top calcium carbide diffusion deoxidation. According to RH, ferrotitanium is added in the later period of high-vacuum circulation, and the soft blow time after calcium treatment is longer than or equal to ten minutes. Protective casting is carried out in the whole process of the continuous casting step, the problems in tundish oxygenation and working procedure recarburization are solved by adopting a covering agent with the low content of ferrous oxide and a low-carbon slag absorbing agent, and a casting blank enters a pit for slow cooling after being discharged out of a production line. With the production method of low-phosphorous gear steel for the automobile gearbox, the technical problem that the gear steel for the automobile gearbox is relatively high in phosphorus content, unstable in ingredient, wide in bandwidthrange of hardenability, and the like is solved.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a production method of low-phosphorus gear steel for automobile gearboxes. Background technique [0002] Gear products for automobiles are developing in the direction of high speed, heavy load, precision and low noise technology, so gear steels are required to have higher machining accuracy and dimensional stability. For high-quality gear steels for automotive transmissions, the basic requirements are to improve the stability and control accuracy of the hardenability of the steel, and to reduce the springback of the gears after heat treatment. A large number of industrial practices have proved that the narrower the hardenability bandwidth of gear steel, the smaller the springback after heat treatment and the higher the dimensional accuracy. Usually the hardenability bandwidth of gear steel does not exceed 6HRC, and the international advanced level reaches the hard...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/50C22C38/44C22C38/42C22C38/06C22C38/04C22C38/02C21C7/06C21C7/10B22D11/111B22D11/114C21D8/06
CPCB22D11/111B22D11/114C21C7/0056C21C7/06C21C7/10C21D8/065C21D2211/005C21D2211/009C22C38/002C22C38/02C22C38/04C22C38/06C22C38/42C22C38/44C22C38/50
Inventor 朱坦华王利伟许海平徐斌肖国华李玉谦肖振会鲁晓旭
Owner HANDAN IRON & STEEL GROUP
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