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Tempering heat treatment method of carburized part and carburized part

A heat treatment method, carburizing and quenching technology, which is applied in the field of carburizing parts and tempering heat treatment of carburizing parts, can solve the problems of poor service reliability, poor resistance to contact fatigue, poor matching of strong plasticity of carburized parts, etc., and achieve strong plasticity Matching optimization, optimization of strong plastic matching, overcoming the effect of long time in the furnace

Active Publication Date: 2020-08-07
CHINA UNIV OF MINING & TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In view of the above analysis, the present invention aims to provide a carburized part tempering heat treatment method and a carburized part, which solves the problem of excessive high-carbon martensite content in the carburized layer after tempering in the prior art. High, resulting in poor strong-plastic matching of carburized parts, poor resistance to contact fatigue, and poor service reliability

Method used

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  • Tempering heat treatment method of carburized part and carburized part
  • Tempering heat treatment method of carburized part and carburized part
  • Tempering heat treatment method of carburized part and carburized part

Examples

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Effect test

Embodiment 1

[0062] Taking 20CrMnTi carburized parts as the base material as an example, the preparation method of the heat treatment method to control the clustering of carbon atoms and the precipitation of substructure transition state carbides can be found in image 3 , the preparation method comprises the steps of:

[0063] Step 1: Carburize the 20CrMnTi part at 930°C for 10 hours, then oil-cool and quench the sample, and detect that the volume fraction of retained austenite is 8%, and no cryogenic treatment is performed;

[0064] Step 2: Place the parts after carburizing and quenching in a tempering furnace at 210° C., keep them warm for 360 minutes, and the generation rate of transition state carbides in the substructure of the samples reaches 90%, and then conduct water cooling treatment.

[0065] After the heat treatment is completed, the carburized layer structure of the 20CrMnTi carburized part is taken for analysis and evaluation. The microstructure characteristics under the tra...

Embodiment 2

[0067] Taking 20CrMnTi carburized parts as the base material as an example, the preparation method of precisely controlling the clustering of carbon atoms and the precipitation of substructure transition state carbides includes the following steps:

[0068] Step 1: Carburize the 20CrMnTi part at 930°C for 30 hours, then oil-cool and quench the sample, detect that the volume fraction of retained austenite is 15%, and perform cryogenic treatment with liquid nitrogen for 30 minutes;

[0069] Step 2: Place the parts after carburizing and quenching in a tempering furnace at 230° C. and keep them warm for 120 minutes. The conversion rate of transition state carbides in the internal substructure of the samples reaches 92%, and then water-cooling treatment.

[0070] The microstructure of the carburized layer after heat treatment is: low-carbon tempered martensite (volume fraction 97.4%) + retained austenite (volume fraction 1%) + high carbon martensite without precipitation of carbide...

Embodiment 3

[0072] Taking 18Cr2Ni4W carburized parts as the base material as an example, the preparation method of precisely controlling the clustering of carbon atoms and the precipitation of substructure transition state carbides includes the following steps:

[0073] Step 1: Carburize the 18Cr2Ni4W part at 930°C for 30 hours, then oil-cool and quench the sample, detect that the volume fraction of retained austenite is 12%, and perform cryogenic treatment for 2 hours.

[0074] Step 2: place the carburized and quenched 20CrMnTi part in a tempering furnace at 240° C., keep it warm for 90 minutes, and the conversion rate of transition state carbides inside the sample reaches 95%, and then water-cooling treatment.

[0075] The microstructure of the carburized layer after heat treatment is: low-carbon tempered martensite (volume fraction 97%) + retained austenite (volume fraction 1.3%) + high carbon martensite without precipitation of carbides (volume fraction 0.8%) + Fe 3C precipitation ty...

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Abstract

The invention discloses a tempering heat treatment method of a carburized part and the carburized part, and belongs to the technical field of heat treatment of metal materials. The method solves the problems that matching of high plasticity is poor, resistance performance to contact fatigue is poor and service reliability is poor due to the fact the content of high-carbon martensite of which carbides are not precipitated is too high in the structure after a carburized layer is tempered in the prior art. The heat treatment method comprises the steps that tempering heat treatment is carried outon the part after carburizing and quenching, and the tempering heat treatment is terminated before Fe3C precipitation-type tempered martensite is formed so as to obtain a carburized layer with volumefraction of the tempered martensite being 90% or above and volume fraction of the Fe3C precipitation-type tempered martensite and bainite being 1% or below, wherein the microstructure of the carburized layer is characterized by carbon atom clustering and substructure transition state carbide precipitation. According to the carburized part prepared by the tempering heat treatment method, the wear resistance is obviously improved, and the contact fatigue service performance is good.

Description

technical field [0001] The invention belongs to the technical field of heat treatment of metal materials, and in particular relates to a carburized part tempering heat treatment method and the carburized part. Background technique [0002] For parts such as shafts and gears that require carburizing and quenching, it is necessary to obtain a carburized layer with a harder surface and a tougher core, and since the main failure mode of such parts is contact fatigue, it is necessary to improve the carburized layer The strength, plasticity, especially the matching of strong plasticity is the key to improve the reliability of such parts. [0003] Carburized parts have a high surface carbon content. Usually, after carburizing and quenching, low-temperature tempering at 150-170°C is used as the last step of the heat treatment process. The main purpose is to remove the quenching stress, and the subsequent tempering heat treatment process is not used. Further improve the ductility of...

Claims

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Application Information

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IPC IPC(8): C21D1/18C21D11/00C23C8/00C21D6/04C21D9/28C21D9/32
CPCC21D1/18C21D6/002C21D6/004C21D6/005C21D6/04C21D9/28C21D9/32C21D11/00C21D2211/001C21D2211/002C21D2211/004C21D2211/008C23C8/00
Inventor 陶庆张天宇沈承金朱真才彭玉兴赖伟潘治州孟庆睿沈刚
Owner CHINA UNIV OF MINING & TECH
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