Waste heat isothermal normalizing treatment method for medium carbon steel forging

A processing method and forging waste heat technology, applied in the field of warm normalizing treatment, can solve the problems of reducing the strength and plasticity of medium carbon steel, increasing brittleness, etc.

Inactive Publication Date: 2017-04-05
YANGZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] Therefore, the problem existing in the prior art is: after forging waste heat isothermal normalizing treatment of medium carbon steel, reticular ferrite appears, which reduces the strength and plasticity of medium carbon steel and increases brittleness

Method used

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  • Waste heat isothermal normalizing treatment method for medium carbon steel forging
  • Waste heat isothermal normalizing treatment method for medium carbon steel forging
  • Waste heat isothermal normalizing treatment method for medium carbon steel forging

Examples

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Effect test

Embodiment 1

[0028] Material: S55C car wheel bearing forging billet, final forging temperature: 900°C (±50°C), the standard requires that the metallographic structure after normalizing is 1-4, and the grain size is ≧4.

[0029] The process of the present invention is as follows: heat preservation at 950°C for 30 minutes, complete austenitization; then take out the sample, cool it in the quenching water-based suspension medium for 8s, and stay in the air for 3s, repeat the above process 12 times; 2 h in an electric resistance furnace, and then cooled to room temperature in air. figure 2 It is the microstructure obtained after the process of the above-mentioned invention is processed. Below the figure is the magnification. image 3 It is the microstructure after direct isothermal normalizing treatment after forging. Below the figure is the magnification. By comparison, it can be seen that figure 2 In the middle, no network ferrite was found at low magnification, and fine and disjointed...

Embodiment 2

[0031] Material: 55 steel hub bearing forging billet, final forging temperature: 900°C (±50°C), performance requirements, hardness after normalizing: HB220-250.

[0032] The process of the present invention is as follows: heat preservation at 950°C for 40 minutes, complete austenitization; then take out the sample, cool it in the quenching water-based suspension medium for 4s, and stay in the air for 4s, repeat the above process 13 times; 1 h in a resistance furnace, and then cooled to room temperature in air. Figure 4 It is the hardness value obtained after the process of the above invention. It can be seen that the hardness values ​​of the five groups of parts are all within the required range, and the fluctuations are not large. The hardness value after the direct isothermal normalizing treatment after the prior art forging is shown in Figure 5 middle. It can be seen that the Brinell hardness of process 1 and process 2 is as follows Figure 4 , 5 As shown, the averag...

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Abstract

The invention discloses a waste heat isothermal normalizing treatment method for medium carbon steel forging. The method comprises the following steps that in the tenth step, austenitizing treatment is conducted, after a medium carbon steel component is forged, austenitizing treatment is conducted within a forging stop temperature range, heat preservation is conducted, and the heat preservation time is determined according to the effective component thickness; in the twentieth step, quenching is conducted, the component obtained after heat preservation is rapidly placed in a flowing water base suspension liquid quenching medium to be cooled and then taken out to stay in air, and the above cooling and staying processes are repeatedly conducted many times; in the thirtieth step, the component is placed in a resistance furnace, and heat preservation is conducted at the normalizing temperature; and in the fortieth step, cooling is conducted, and the component obtained after normalizing is taken out and cooled to the room temperature in air. According to the waste heat isothermal normalizing treatment method for medium carbon steel forging, network ferrite cannot occur, strength and plasticity are not lowered, and brittleness is not increased.

Description

technical field [0001] The invention belongs to the technical field of forging heat treatment, in particular to an isothermal normalizing treatment method for medium-carbon steel forging residual heat without reticular ferrite, strength and plasticity reduction, and brittleness increase. Background technique [0002] Adopting the isothermal normalizing process with forging waste heat can greatly save the energy consumption of forging heat treatment, shorten the production cycle of forgings, and improve production efficiency and product quality. [0003] Due to its good comprehensive mechanical properties, medium carbon structural steel can be manufactured into bearing parts such as shafts, bolts and balance shafts, and is widely used in ships, automobiles, infrastructure and other fields. [0004] However, medium carbon steel, especially medium carbon steel with a carbon content of 0.5-0.6wt%, will first precipitate proeutectoid ferrite from austenite when it is cooled from ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/18C21D1/28
CPCC21D1/18C21D1/28
Inventor 刘澄崔锡锡杨晨华高赵振波张剑峰高吉成周睿
Owner YANGZHOU UNIV
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