Heat treatment technology for high-carbon chromium bearing ring with extremely low retained austenite

A technology of residual austenite and high-carbon chromium bearings, which is applied in heat treatment furnaces, heat treatment equipment, and improvement of process efficiency, can solve problems such as insufficient austenite cooling transformation, reduced bearing life, failure deformation, etc., and promotes More fully transform, increase the quenching cooling rate, and promote the effect of further transformation

Inactive Publication Date: 2018-09-07
LUOYANG LUOLING BEARING SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] It is well known that during the quenching and tempering process of high-carbon chromium bearing rings, due to insufficient austenite cooling transformation, there is a certain amount of residual austenite after heat treatment; at present, the national standard JB / T 1255-2014 rolling bearing high The technical conditions for heat treatment of carbon chromium bearing steel parts are classified according to bearing tolerances, the retained austenite content of P2 and P4 grades is ≤5%, and the retained austenite content of P0, P5, P6, and P6X grades is ≤15%; austenite is due to its low Hardness and low wear resistance will reduce the life of the bearing. At the same time, as an unstable structure, the retained austenite is prone to dimensional changes, failure deformation and aging cracking. During the use of the bearing, the transformation of the retained austenite will cause Serious bearing service life; therefore, reducing the content of retained austenite is of great benefit to the service life of bearings, especially precision bearings

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] The heat treatment process of GCr15 bearing rings, taking the DGBB bearing rings (model 6219, 6313 or 6320) on the production line as an example, specifically includes the following steps:

[0032] a) The temperature in the quenching and holding zone is 835°C, and the holding time is 60 minutes;

[0033] b), cooling, cooling temperature 190 ° C, cooling medium: composition is 50% sodium nitrite and 50% potassium nitrate salt;

[0034] c), air-cooled, using axial flow fan 4-stage air-cooled, single station time 6 minutes;

[0035] d) Cleaning, 2-stage cleaning, the temperature is controlled at 50°C and room temperature respectively, and the single-station time is 6 minutes;

[0036] e) Spray cooling is used for secondary cooling at a temperature of 7°C;

[0037] f) The tempering temperature is 240°C and the time is 240 minutes.

[0038] After polishing the surface of the sample for inspection, place it on the X-350A X-ray stress tester for residual austenite analysis:...

Embodiment 2

[0040] The heat treatment process of GCr15 bearing ring, taking the CRB bearing ring (model NU2216, NU314 or NU330) on the production line as an example, specifically includes the following steps:

[0041] a) The temperature in the quenching and holding zone is 837°C, and the holding time is 63 minutes;

[0042] b), cooling, cooling temperature 193 ° C, cooling medium: composition is 50% sodium nitrite and 50% salt of potassium nitrate;

[0043] c), air-cooled, using axial flow fan 4-stage air-cooled, single station time 6 minutes;

[0044] d) Cleaning, 2-stage cleaning, the temperature is controlled at 53°C and room temperature respectively, and the time for a single station is 6 minutes;

[0045] e) Spray cooling is used for secondary cooling, and the temperature is 7±2°C;

[0046] f), the tempering temperature is 243°C, and the time is 242 minutes.

[0047] After polishing the surface of the sample for inspection, place it on the X-350A X-ray stress tester for residual a...

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PUM

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Abstract

The invention relates to a heat treatment technology for a high-carbon chromium bearing ring with extremely low retained austenite, and relates to the technical field of heat treatment technologies. The heat treatment technology specifically comprises the following steps of holding the high-carbon chromium bearing ring heat-treated for 60+ / -5 min at 835+ / -5 DEG in a quenching heat preservation area; cooling the high-carbon chromium bearing ring held in the first step, the temperature of cooling medium which is salt is 190+ / -5 DEG C; air-cooling the high-carbon chromium bearing ring cooled in the second step, the level of the air cooling is 4, and the time for a single station is 6 min; going on the last step, performing secondary cleaning, the cleaning temperature is controlled within 50+ / -5 DEG C, then performing cleaning at room temperature, the time for the single station is 6 min; and performing secondary cooling and tempering. According to the heat treatment technology, through multi-stage air cooling, cleaning, selection of a proper cooling amount and cleaning temperature, adding of secondary cooling and the tempering process, the retained austenite is changed thoroughly, andfinally the retained austenite of the high-carbon chromium bearing ring is no more than 3%.

Description

technical field [0001] The invention relates to the technical field of heat treatment processes, in particular to a heat treatment process for high-carbon chromium bearing rings with extremely low residual austenite. Background technique [0002] It is well known that during the quenching and tempering process of high-carbon chromium bearing rings, due to insufficient austenite cooling transformation, there is a certain amount of residual austenite after heat treatment; at present, the national standard JB / T 1255-2014 rolling bearing high The technical conditions for heat treatment of carbon chromium bearing steel parts are classified according to bearing tolerances, the retained austenite content of P2 and P4 grades is ≤5%, and the retained austenite content of P0, P5, P6, and P6X grades is ≤15%; austenite is due to its low Hardness and low wear resistance will reduce the life of the bearing. At the same time, as an unstable structure, the retained austenite is prone to dim...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/18C21D9/40C21D1/607
CPCC21D1/18C21D1/607C21D9/40C21D2211/008Y02P10/20
Inventor 陈亚杰刘长建马志杰郭睿东
Owner LUOYANG LUOLING BEARING SCI & TECH
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