JB/T 7363-1994 Technical conditions for carbonitriding heat treatment of rolling bearing parts JB/T7363-1994 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
JB/T7363-94
Carbonitriding of rolling bearing parts
Technical conditions for heat treatment
Published on July 26, 1994
Ministry of Machinery Industry of the People's Republic of China
Implementation on July 1, 1995
Mechanical Industry Standard of the People's Republic of China
Carbonitriding of rolling bearing parts
Technical conditions for heat treatment
1 Subject content and scope of application
This standard specifies the technical requirements for carbonitriding of rolling bearing parts and the measurement method of the effective hardened layer depth. JB/T7363-94
This standard is applicable to the carbonitriding heat treatment quality inspection of 15CrMo, 20CrMo, 20CrMnTi, 20, 10, 08A1 and other steel cages and 10.08Al. steel needle roller bearing stamping outer ring (thin-walled stretched outer ring) (effective hardened layer depth is less than or equal to 0.3mm). The carbonitriding heat treatment quality of steel bearing parts with an effective hardened layer depth less than or equal to 0.3mm can also be implemented as a reference. 2 Reference standards
GB9451Www.bzxZ.net
Determination of the total hardened layer depth or effective hardened layer depth of thin surfaces of steel parts GB/T4342 Metal micro-Vickers hardness measurement method 3 Technical requirements
3.1 The effective hardened layer depth of carbonitriding shall comply with the provisions of the product drawings. 3.2 The surface hardness of the cage after direct quenching and tempering of the parts is 620~766HV; the surface hardness of the stamped outer ring is 664~795HV, and the hardness of the core should meet the requirements of the product drawings. 3.3 The structure of the carbonitriding layer should be nitrogen-containing martensite, retained austenite and carbonitride. The surface carbon content is 0.75%~0.85%, and the nitrogen content is 0.15%~0.30%. The structure of the carburized layer is evaluated according to the microstructure diagram of the carbonitriding layer of this standard (standard picture description of carburizing structure). Figures 1 and 2 are qualified, and levels 1 and 2 of Figure 3 are unqualified. The core structure can be lath martensite, pearlite, and ferrite depending on the material. 3.4 Deformation of the cage and thin-walled stretched outer ring The diameter change of the cage and thin-walled stretched outer ring after heat treatment is controlled according to Table 1. Table 1
Parts outer diameter
>30~50
4 Inspection method
Selection and preparation of samples
Diameter variation (maximum)
Cage Take the window lintel, and cut a thin villa stretch outer ring along the axial direction (cross section, longitudinal section are both acceptable) for metallographic observation and microhardness measurement. The sample preparation should be in accordance with the surface metallographic analysis sample preparation requirements. Grinding and polishing should ensure that the sample edge has no chamfers or curling. For this reason, the sample can be protected by inlay or special clamps. If necessary, the edge of the sample to be tested should be protected by copper sheets or electroplated metal. 4.2 Effective hardening layer depth measurement
4.2.1 Microstructure measurement method
For carbonitriding, annealing and tempering test pieces, the test can be measured with the aid of a microscope micrometer eyepiece or directly on the microscope frosted glass screen. Approved by the Ministry of Machinery Industry on July 26, 1994
Implementation on July 1, 1995
JB/T7363-94
The effective hardening layer depth is the vertical distance from the surface to the core where the structure changes. 4.2.2 Microhardness measurement method
Measure according to the methods specified in GB9451 and GB/T4342. The test force selected for microhardness measurement is 1.96N (0.2kgf) ~ 2.9N (0.3kgf). The distance between the center of the indentation closest to the surface and the surface of the specimen is approximately twice the length of the diagonal of the indentation, and the distance between two adjacent indentations must be at least 2.5 times the length of the diagonal of the indentation. The effective hardened layer depth is the vertical distance between the surface of the part and the place where the core structure changes.
4.3 Hardness measurement
4.3.1 Measurement method
The surface and core hardness are measured by microhardness method, and the test force is in accordance with the provisions of Article 4.2.2. 4.3.2 Measurement location
4.3.2.1 Surface hardness measurement location
The surface hardness of the cage is based on the measured value of the cage beam surface. The surface hardness of the thin-walled tensile outer ring can be measured directly on the end face if the end face is flat, and can be measured with a specimen of the same wall thickness if the end face is uneven. 4.3.2.2 Core hardness measurement position
The core hardness of the cage shall be measured at 1/2 of the cage cross section, and the core hardness of the thin-walled tensile outer ring shall be measured at 1/2 of the sampling section.
4.4 Observation and measurement of the carburized layer structure
The surface carburized layer structure can be observed and measured under a microscope with a magnification of 100 times. If there is any objection, 400 times shall prevail. The sample was not corrosive with 2% to 4% nitric acid alcohol solution.
5 Test report
The test report must be filled in by the inspector, including: product production date and batch number, inspection and inspection date, product specifications, code, material and heat treatment process, effective hardened layer depth, surface hardness, core hardness, carburized layer structure, core structure and other test data to determine whether the product is qualified or not, and signed by the tester and proofreader. Microstructure diagram of carbonitriding layer
Figure 1400×
Figure 2400×
Additional notes:
Level 1 400×
JB/T7363--94
Table 2 Description of carbonitriding microstructure diagram
Description of metallographic picture level
A small amount of carbon and nitrogen compounds
+ Nitrogen-containing martensite + a small amount of retained austenite
Ammonia-containing martensite + a small amount of retained austenite
Surface black structure
+ Nitrogen-containing martensite + a small amount of retained austenite More black structure appears on the surface
+ Nitrogen-containing martensite + a small amount of retained austenite This standard is proposed by the Standardization Technical Committee of Rolling Bearing Industry. Level 2
This picture is deep etching, mainly to show a small amount of carbon and nitrogen compounds on the surface (Figure 1). If the 10μme phase (self-color nitrogen-rich area) appears on the surface, it is normal tissue
The black tissue is the oxide produced by internal oxidation, or the product of medium-temperature decomposition of austenite around the oxide, with a network structure. After polishing, it is not shown that the carbon and nitrogen concentration is not appropriate, especially the nitrogen content is too high, which reduces the surface density and makes the parts brittle
This standard is under the jurisdiction of the Luoyang Bearing Research Institute of the Ministry of Machinery Industry and is responsible for drafting. The main drafters of this standard are Chen Xin, Xiao Zhenyu, and Yang Qiaoling. 3
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