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Isothermal normalizing process for carburizing steel gear

A technology of isothermal normalizing and carburizing steel, which is applied in the field of heat treatment, can solve the problems of obvious segregation and affect the mechanical properties and service life of carburized steel gears, and achieve the effect of improving segregation, improving mechanical properties and prolonging service life

Inactive Publication Date: 2017-03-15
WUXI BAOLU FORGING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide an isothermal normalizing process for carburized steel gears, so as to solve the problem of obvious segregation and affecting the mechanical properties and service life of carburized steel gears when conventional normalizing processes are used to treat carburized steel gears

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] In this embodiment, an isothermal normalizing process for carburized steel gears includes the following steps:

[0017] a. Put the gear formed by carburizing steel forging into the heating furnace, heat it to 915°C, and keep it warm for 5.3h;

[0018] b. After the heat preservation is over, take out the gear and carry out air cooling at a cooling rate of 75°C / h;

[0019] c. When the temperature of the gear is cooled to 675°C, place it in a holding furnace with a temperature of 660°C to cool the gear slowly. When the temperature of the gear is cooled to 660°C, keep it warm for 6.5 hours;

[0020] d. After the heat preservation is over, take out the gear and air cool to room temperature.

[0021] The segregation of the gear produced by the above process is obviously improved, the band structure is reduced, and the tensile strength can be increased by 13%, the elongation can be increased by 13%, and the impact toughness can be increased by 25%.

Embodiment 2

[0023] In this embodiment, an isothermal normalizing process for carburized steel gears includes the following steps:

[0024] a. Put the gear formed by carburizing steel forging into the heating furnace, heat it to 925°C, and keep it warm for 4.7h;

[0025] b. After the heat preservation is over, take out the gear and carry out air cooling at a cooling rate of 85°C / h;

[0026] c. When the temperature of the gear is cooled to 685°C, place it in a holding furnace with a temperature of 660°C to cool the gear slowly. When the temperature of the gear is cooled to 660°C, keep it warm for 5.5 hours;

[0027] d. After the heat preservation is over, take out the gear and air cool to room temperature.

[0028] The segregation of the gear produced by the above process is obviously improved, the band structure is reduced, and the tensile strength can be increased by 15%, the elongation can be increased by 12%, and the impact toughness can be increased by 23%.

Embodiment 3

[0030] In this embodiment, an isothermal normalizing process for carburized steel gears includes the following steps:

[0031] a. Put the gear formed by carburizing steel forging into the heating furnace, heat it to 920°C, and keep it warm for 5 hours;

[0032] b. After the heat preservation is over, take out the gear and carry out air cooling at a cooling rate of 80°C / h;

[0033] c. When the temperature of the gear is cooled to 680°C, place it in a holding furnace with a temperature of 660°C to cool the gear slowly. When the temperature of the gear is cooled to 660°C, keep it warm for 6 hours;

[0034] d. After the heat preservation is over, take out the gear and air cool to room temperature.

[0035] The segregation of the gear produced by the above process is obviously improved, the band structure is reduced, and the tensile strength can be increased by 20%, the elongation can be increased by 15%, and the impact toughness can be increased by 30%.

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Abstract

The invention discloses an isothermal normalizing process for a carburizing steel gear. The isothermal normalizing process comprises the following steps: (a) putting a gear which is formed by forging carburizing steel into a heating furnace, heating to the temperature of 915 to 925 DEG C and maintaining the temperature for 4.7 to 5.3 hours; (b) taking out the gear after temperature maintaining is ended, and performing air cooling at a cooling speed of 75 to 85 DEG C / h; (c) putting the gear in a heat maintaining furnace of which the temperature is 660 DEG C after the gear is cooled to the temperature of 675 to 685 DEG C, slowly cooling the gear, and maintaining the temperature for 5.5 to 6.5 hours after the gear is cooled to the temperature of 660 DEG C; and (d) taking out the gear after temperature maintaining is ended, and performing air cooling until the gear reaches a room temperature. According to the isothermal normalizing process for the carburizing steel gear, the air cooling speed is controlled and the gear is retuned to the furnace to be slowly cooled to the temperature of 660 DEG C after the gear is cooled to the temperature of 675 to 685 DEG C, and then temperature is maintained so that formation of proeutectoid ferrite is inhibited, a produced steel forge piece is obviously improved in segregation condition, banded structures are reduced, the mechanical properties are improved and the service life is prolonged.

Description

technical field [0001] The invention relates to the field of heat treatment, in particular to an isothermal normalizing process for carburized steel gears. Background technique [0002] Carburizing steel is a kind of steel that can withstand carburizing and quenching to improve the surface hardness and wear resistance while maintaining proper strength and toughness in the core. Carburized steel is widely used in the manufacture of gears in wind power, reducers, locomotives and other industries. The existing carburized steel gears need to be normalized after being forged, and then, after the conventional normalizing process, the segregation is obvious, which affects the mechanical properties and service life of the carburized steel gears. Therefore, it is urgent to solve . Contents of the invention [0003] The purpose of the present invention is to provide an isothermal normalizing process for carburized steel gears to solve the problem of obvious segregation and affecti...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/28C21D9/32
CPCC21D1/28C21D9/32
Inventor 华志伟
Owner WUXI BAOLU FORGING