Surface refining process for high-carbon chromium (GCr15) bearing after carbonitriding treatment

A carbonitriding and high-carbon chromium technology, which is applied in the field of surface refinement technology after carbonitriding of high-carbon chromium bearings, can solve the problems of bearing failure, large tensile stress, and reducing the beneficial effects of high paralympic content.

Inactive Publication Date: 2010-06-23
SHANGHAI C&U GRP CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the carbonitrides in the surface microstructure of the parts treated by this process are in the form of large blocks or even shells. This structure will greatly reduce the beneficial effects of high residual content during the use of the bearing, and even increase the brittleness of the bearing. Serious failure of bearings often occurs, causing unpredictable accidents
Since the surface of the GCr15 bearing after conventional heat treatment has a very small amount of retained austenite and a large tensile stress, such a bearing is very prone to failure when used in harsh working conditions (such as automotive transmissions, etc.)

Method used

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  • Surface refining process for high-carbon chromium (GCr15) bearing after carbonitriding treatment
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  • Surface refining process for high-carbon chromium (GCr15) bearing after carbonitriding treatment

Examples

Experimental program
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Effect test

Embodiment 1

[0009] Example 1: Heat the bearing ring to 810°C, keep the carbon potential at 1.0-1.5 in a carbon-nitrogen atmosphere, and keep the nitrogen potential at 2-6% for 1.0 hour, then quench it with 30°C oil, and then heat the bearing Heat the ring to 500°C for stress relief and tempering for 2 hours, then heat the bearing ring to 800°C for 0.5 hour, quench it with 30°C oil, and then heat the bearing ring to 150°C for 2 hours. After testing and testing, the surface residual austenite content is 25-30%, and the surface stress is 200-300Mpa compressive stress. After testing, there are no large carbonitrides on the surface, and the maximum carbonitride size is 25μm; enhanced fatigue life test After that, the minimum life of the test bearing is 801 hours, which is greater than 9L 10 (L 10 87 hours), a total of 8 sets of test bearings, the reliability is greater than 99.5%.

Embodiment 2

[0010] Example 2: Heat the bearing ring to 825°C, keep the carbon potential at 1.0-1.5 in a carbon-nitrogen atmosphere, and keep the nitrogen potential at 2-6% for 2.5 hours, then quench it with 65°C oil, and then put the bearing Heat the ring to 550°C for stress relief and tempering for 2.5 hours, then heat the bearing ring to 815°C for 1.2 hours, then quench it with 65°C oil, then heat the bearing ring to 180°C for 2.5 hours. After testing and testing, the surface residual austenite content is 27-35%, and the surface stress is 200-400Mpa compressive stress. After testing, there are no large carbonitrides on the surface, and the maximum carbonitride size is 20μm;; Enhanced fatigue life After the test, the minimum life of the test bearing is 889 hours, greater than 10L 10 (L 10 87 hours), a total of 8 sets of test bearings, the reliability is greater than 99.5%.

Embodiment 3

[0011] Example 3: Heat the bearing ring to 840°C, keep the carbon potential at 1.0-1.5 in the carbon-nitrogen atmosphere, and keep the nitrogen potential at 2-6% for 3 hours, then quench it with 100°C oil, and then the bearing The ring is heated to 600°C for stress relief and tempering for 3 hours, then the bearing ring is heated to 830°C for 1.5 hours, then quenched with 100°C oil, and then the bearing ring is heated to 200°C for 3 hours and tempered. After testing and testing, the surface residual austenite content is 27-35%, and the surface stress is 200-400Mpa compressive stress. After testing, there are no large carbonitrides on the surface, and the maximum carbonitride size is 20μm;; Enhanced fatigue life After the test, the minimum life of the test bearing is 889 hours, greater than 10L 10 (L 10 87 hours), a total of 8 sets of test bearings, the reliability is greater than 99.5%.

[0012] The testing of the above test bearings is carried out according to the bearing m...

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Abstract

The invention relates to a surface refining process for a high-carbon chromium (GCr15) bearing after carbonitriding treatment, which is characterized by comprising the following steps: insulating a bearing ring for 1.5-3 hours at the temperature of 810-840 DEG C under the carbon and nitrogen atmosphere conditions that the carbon potential is 1.0-1.5 and the nitrogen potential is 2-6%, and then carrying out quenching, wherein the quenching temperature is 810-840 DEG C; heating the bearing ring to 500-600 DEG C, eliminating the stress and tempering for 2-3 hours; heating the bearing ring to 800-830 DEG C, insulating for 0.5-1.5 hours, and then carrying out quenching again, wherein the quenching temperature is 800-830 DEG C; and then, heating the bearing ring to 150-200 DEG C, and tempering for 2-3 hours. The two quenching processes are carried out by using oil of 30-100 DEG C. The invention has the advantage of refining the carbonitride penetrating into the surface of the bearing ring, thereby being more favorable for prolonging service life of the bearing.

Description

technical field [0001] The invention relates to a process for refining the surface of a high-carbon chromium (GCr15) bearing after carbonitriding treatment. Background technique [0002] The current conventional GCr15 bearing steel surface carbonitriding process: the bearing ring is at a lower temperature (810-840 ° C), a higher carbon-nitrogen atmosphere (the carbon potential is controlled at 1.0-1.5, and the nitrogen potential is controlled at 2 ~6%) and heat for 1.5 to 3 hours, followed by quenching and tempering. According to this heat treatment process, the residual austenite content of the bearing ring is 25-35%, and the surface is in a state of relatively large compressive stress. However, the carbonitrides in the surface microstructure of the parts treated by this process are in the form of large blocks or even shells. This structure will greatly reduce the beneficial effects of high residual content during the use of the bearing, and even increase the brittleness o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/18
Inventor 刘斌郭长建高向阳
Owner SHANGHAI C&U GRP CO LTD
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