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Gear steel 20CrMnTiH isothermal normalizing treatment method

A technology of isothermal normalizing and treatment method, applied in heat treatment equipment, heat treatment process control, manufacturing tools, etc., can solve the problems of unstable process, low pass rate, uneven hardness, etc., and achieve the effect of process stability

Active Publication Date: 2017-01-25
SHOUGANG CORPORATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The normalizing process of automotive gear blanks is generally austenitized at 930°C. It takes 50 minutes to cool the steel evenly to 550°C, and then cools the steel evenly to 250°C for 100 minutes and then air-cools. The control is difficult, and the process is generally unstable.
For example, Chinese patent CN101429587A discloses a car differential gear isothermal normalizing treatment, which only cools the forging to 600-720 degrees Celsius under the condition of nitrogen air cooling, and does not limit the cooling rate, nitrogen temperature, nitrogen speed and other conditions , resulting in unstable final material properties, uneven hardness, and low pass rate

Method used

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  • Gear steel 20CrMnTiH isothermal normalizing treatment method
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  • Gear steel 20CrMnTiH isothermal normalizing treatment method

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Embodiment 1

[0033] The present invention is applied in the isothermal normalizing after forging of 40mm gear steel 20CrMnTiH gear blank, and the steps are as follows: (a) After austenitizing and heating, the warm air cooling process is adopted: in the first zone, the warm air temperature is 50°C, and the wind speed is controlled At 12m / s, the air cooling time of the parts is controlled at 3min; in the second zone, the air temperature is 55°C, the wind speed is 8m / s, and the air cooling time of the parts is controlled at 4min b) Adjust the isothermal normalizing furnace into two stages of control: the first stage The temperature is controlled at 550°C, and the holding time is 1.5h; the temperature of the second stage is controlled at 570°C, and the isothermal time is 1.5h. (c) After isothermal normalizing, enter the air-cooled room, control the air temperature at 30°C and the wind speed at 8m / s, cool to 250°C, and then air-cool. The hardness of the tooth blank treated by this process can r...

Embodiment 2

[0035] The present invention is applied in isothermal normalizing after forging a 30mm gear steel 20CrMnTiH tooth blank, and the steps are as follows:

[0036] (1) Warm air partition cooling process is adopted after austenitizing heating: in the first area, the warm air temperature is 55°C, the wind speed is controlled at 8m / s, and the air cooling time of parts is controlled at 2min; in the second area, the air temperature is 60°C, and the wind speed 5m / s, the air cooling time of parts is controlled at 3min

[0037] (2) Adjusting the isothermal normalizing furnace is divided into two stages of control: the temperature of the first stage is controlled at 570°C, and the holding time is 1h; the temperature of the second stage is controlled at 600°C, and isothermal for 1h.

[0038] (3) After isothermal normalizing, enter the air-cooled room, the air temperature is controlled at 40°C, the wind speed is controlled at 5m / s, and after cooling to 200°C, it is air-cooled. The hardness ...

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Abstract

The invention discloses a gear steel 20CrMnTiH isothermal normalizing treatment method, and belongs to the field of material thermal treatment. The gear steel 20CrMnTiH isothermal normalizing treatment method comprises the steps: adopting a warm-air district cooling technology after austenitizing heating: in district I, the warm air temperature is 50 to 55 DEG C, the air speed is controlled to be 8 to 12 m / s, and the air cooling time of parts is controlled to be 2 to 3 minutes; in district II, the air temperature is 55 to 60 DEG C, the air speed is 5 to 8 m / s, and the air cooling time of parts is controlled to be 3 to 4 minutes; regulating an isothermal normalizing furnace to be in two-stage control: first stage, the temperature is controlled to be 550 to 570 DEG C, and the heat preservation time is 1 to 1.5 hours; second stage, the temperature is controlled to be 570 to 600 DEG C, and the isothermal control time is 1 to 1.5 hours; after isothermal normalizing, entering an air cooling chamber, controlling the air temperature to be 30 to 40 DEG C and the air speed to be 5 to 8 m / s, and carrying out air cooling after cooling to 200 to 250 DEG C. The hardness of gear blank treated by the technology can be up to 165 to 180 HB, the pearlite interlamellar spacing is controlled to be 0.18 to 0.24 mu m, the grade of a banded structure is controlled to be 1 to 1.5, the cutting performance is good, deformation after quenching can be stably controlled, and the reject ratio is basically zero.

Description

technical field [0001] The invention belongs to the field of material heat treatment, and in particular relates to a gear steel 20CrMnTi isothermal positive treatment method. After this heat treatment process, the structure and hardness of the gear steel blank parts are optimized, which is very suitable for chip processing and is a subsequent part. Advanced finishing and heat treatment provide tissue performance guarantee. Background technique [0002] In automobile production, gears are essential and basic parts. When the quality of the gears, especially the gears of the rear axle gear transmission is low, there will be problems such as difficult assembly, high noise and tooth surface wear. Carburizing and quenching deformation is one of the reasons that affect the quality of the assembly. Among the factors affecting deformation, it is often concentrated on carburizing and quenching, and it is easy to ignore the influence of pre-heat treatment of forging billet on deforma...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/28C21D11/00
CPCC21D1/28C21D11/00C21D2211/001
Inventor 王猛崔京玉罗志俊王丽萍王立峰李舒笳佟倩王晓晨杨子森孔祥涛
Owner SHOUGANG CORPORATION
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