JB/T 8881—2001 This standard is a revision and merger of JB/T 8881—1999 and JB/T 8882—1999. The control level of carburized layer network carbides for effective hardened layer depth was added during the revision; the surface and core hardness of carburized bearing parts were modified. This standard specifies the technical requirements for heat treatment, carburization, high temperature tempering, quenching and tempering of rolling bearing parts made of carburized bearing steels such as G20CrMo(A), G20GrNiMo(A), G20CrNi2Mo(A), G20Cr2Ni4(A), G10CrNi3Mo(A) and G20Cr2MnMo(A) in accordance with GB/T 3203 "Technical Conditions for Carburized Bearing Steels", as well as the measurement of effective carburized hardened layer depth, hardness, microstructure, surface cracks and other inspection procedures. This standard applies to the carburizing heat treatment quality inspection of the above-mentioned carburizing bearing steel and low-carbon alloy steel rolling bearing parts that can meet the requirements of this standard. For bearing parts with special requirements. The quality of carburizing heat treatment should be in accordance with the product drawings and relevant technical conditions. The previous versions of the standards replaced by this standard are: ——ZB J36 001-1986, JB/T 8881-1999 (adjustment); ——ZB J36 002-1986, JB/T 8882-1999 (adjustment). JB/T 8881-2001 Technical conditions for carburizing heat treatment of rolling bearing parts JB/T8881-2001 Standard download decompression password: www.bzxz.net

ICS 21. 100. 20
Machinery Industry Standard of the People's Republic of China
FB/T8881-2001
Rolling Bearing Parts
Specifications for carburizing heat treatment of rolling bearing parts
Published on 2001-05-23
Published by China Machinery Industry Federation
Implemented on 2001-10-01
JB/T 8881-2001
1 Scope
2 Reference standards
3 Technical requirements
4 Measurement, inspection and evaluation methods
Appendix A (Appendix to the standard) Method for measuring the depth of effective carburized hardened layer Appendix B (Appendix to the standard) Procedure for detecting defects with dye penetrant inspection: Appendix C (Appendix to the standard) Allowable deformation of carburized bearing rings 13
JB/T8881-2001
This standard is a revision of JB/T8881-1999 (formerly numbered ZBJ36001-1986) "Quality Standard for Carburizing Heat Treatment of Rolling Bearing Parts" and JB/T8882-1999 (formerly numbered ZB336002-1986) "Quality Standard for Deep Carburizing Heat Treatment of Rolling Bearing Parts".
Compared with the original standard, the main technical contents of this standard have been changed as follows: 1. The name of the standard has been changed to "Technical Conditions for Carburizing Heat Treatment of Rolling Bearing Parts", and the two original standards have been merged into one: the control level of carburizing layer network carbides for deep carburizing with effective hardening layer depth = 2.5mm has been added: the surface and core hardness of carburized bearing parts have been modified. Appendix A, Appendix B and Appendix C of this standard are all appendices of the standard. This standard replaces JB/T8881--1999 and JB/T88821999 from the date of implementation. This standard is proposed and managed by the National Technical Committee for Standardization of Rolling Bearings. The responsible drafting units of this standard are: Luoyang Bearing Research Institute, Xiangfang Group Co., Ltd. The main drafters of this standard are: Mei Yali, Yang Jianhong, Lei Jianzhong, Chen Xin, Yang Qiaoling, Li Hong. The versions of the standards replaced by this standard are: - ZBJ36001-1986, JB/T8881-1999 (adjustment) - ZBJ36002-1986, JB/T8882-1999 (adjustment). 1 Scope
Machinery Industry Standard of the People's Republic of China
Specifications for carburizing heat treatment of rolting bearing parts
JB/T 881-2001
Replaces JB/T 888[—1999
JB/T 8882--1999
This standard specifies the technical requirements for forging heat treatment, carburizing high temperature tempering and annealing, and tempering of rolling bearing parts made of carburizing bearing steels such as G20CrMo (A), G20CrNiMo (A), G20CrNi2Mo (A), G20Cr2Ni4 (A), GI0CrNi3Mo (A) and G20Cr2Mn2Mo (A) in accordance with GB/T3203, as well as the measurement of effective carburized hardened layer depth, hardness, microstructure, surface cracks and other inspection procedures
This standard is applicable to the carburizing heat treatment quality inspection of the above-mentioned carburized bearing steels and low-carbon alloy steel rolling bearing parts that can meet the requirements of this standard. For bearing parts with special requirements, the carburizing heat treatment quality shall be in accordance with the product drawings and the provisions of relevant technical parts. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. The versions shown are valid at the time of publication of this standard. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest version of the following standards. GB/T 230-—1991
GB/T 231-1984
GB/T 3203--1982
GBT4340.1—1999
GB/T 9450—1988
JB/T1255—2001
3 Technical requirements
3.1: Technical requirements for heat treatment of forgings
Metal Rockwell hardness test method
Metal Brinell hardness test method
Technical conditions for carburized bearing steel
Metal Vickers hardness test Part 1: Test method Determination and verification of carburizing rate and effective carburizing layer depth of steel parts Technical conditions for heat treatment of high carbon chromium bearing steel rolling bearing parts The hardness of forgings of bearing parts or after heat treatment shall not be greater than 229HB, that is, the indentation diameter shall not be less than 4.0mm. The hardness of forgings made of G20Cr2Ni4 (A) shall not be greater than 241HB, that is, the indentation diameter shall not be less than 3.9mm. 3.2 Technical requirements after carburizing, high temperature tempering, and rate annealing and tempering 3.2.1 Surface carbon content
The surface carbon content of carburized bearing products and other parts should be 0.80%~1.05%, and the surface carbon content of deep carbon with an effective hardened layer depth of ≥2.5mm should not be less than 0.80%. If there are special requirements, they can be specified separately if the surface hardness is qualified. 3.2.2 Carbides
5.2.2.1 After carbon treatment, the depth of coarse carbides in the carburized surface layer shall not exceed 2/3 of the minimum single-side wear amount. The measurement method of the disc China Machinery Industry Federation approved on May 23, 2001 and implemented on October 0, 2001
can be in accordance with the provisions of the coarse carbide measurement diagram of this standard. :JBYT $R81-2001
3.2.2.2" The coarse carbides remaining on the working surface of the finished parts shall be evaluated according to the first level diagram of this standard based on their size, quantity and distribution. Levels 1 and 2 are qualified, and level 3 for deep carburizing with an effective hardening layer depth of 2.5mm is also qualified. 3.2.2.3 The network carbides on the surface of the finished parts shall be evaluated according to the second level diagram of this standard based on the size and degree of closure of the carbide network. Levels 1-3 are qualified.
3.2.3 Hardness
The surface hardness and core hardness of carburized bearing parts after direct annealing (or secondary annealing) and tempering after carburization shall comply with 3.2, 3. 13
Regulations.
Table 1 Surface and core hardness of carburized bearing parts Steel grade
Effective free carbon
Deepness of hardened layer
G20CrMo（A）
G20CrNiMo tA)
G20CrNi2Mo (A)
G20Cr2Ni4 (A)
G20Cr2Ni4 (A)
GI0CrN3Mo（A）
G20Cr2Mn2Mo (A)
Core hardness
Surface hardness
After carburizing, quenching or secondary annealing
After the same size
3.1.3.2 When there is no provision in the product drawing, the surface hardness difference of the same part should not be greater than 2HRC. When the effective hardening depth is 2.5mm, the uniformity of the surface hardness does not need to be checked.
3.2.4 Effective carburizing hardening layer depth
The effective carburizing hardening layer depth of the finished bearing parts shall comply with the provisions of the product drawing or Table 2. Table 2 Effective carburizing hardening layer depth of bearing parts Effective thickness or effective true diameter of bearing parts
1 The effective carburizing hardening layer depth of the inner and outer peripheries of bearings of the same model is the same. And the outer effective wall thickness shall prevail. 2 The effective full thickness or effective diameter of the bearing parts shall be calculated according to BT 1255-200I Appendix G. 2
Effective free carburized hardened layer depth
3.2.5 Microstructure
JBFT 8881-2001
3.2.5.1 Microstructure of the carburized layer after quenching and high temperature tempering The microstructure of the carburized layer after quenching and high temperature tempering should be a fine, evenly distributed pearlite type structure, while allowing a small amount of retained austenite and a certain amount of intermittent, fine needle-shaped carbides. It can be evaluated according to the third level diagram of this standard based on the morphology of the pearlite type structure, the size and quantity of needle-shaped carbides and the amount of retained austenite. Levels 1 to 3 are qualified, and those greater than level 3 are unqualified. 3.2.5.2 Microstructure of the surface layer after carburizing, quenching or secondary quenching and tempering The microstructure of the surface layer after carburizing, quenching or secondary quenching and tempering is evaluated according to the coarseness of martensite and the content of residual austenite. Carburizing, direct quenching and tempering are evaluated according to the fourth level diagram of this standard. Levels 2 to 4 are qualified organizations. Carburizing, quenching + (or high temperature tempering) secondary quenching + tempering are evaluated according to the fifth level diagram of this standard. Levels 1 to 3 are qualified organizations; for G20Cr2Ni4 (A) and parts with an effective carburizing hardening layer depth of 22.5mm, a certain degree of fine needle-shaped martensite and a small amount of intermittent residual needle-shaped carbides are allowed to exist, and Level 4 is also a qualified organization. 3.2.5.3 Core organization
The core organization should be lath martensite, bainite and a small amount of ferrite is allowed to exist. It can be evaluated according to the sixth level diagram of this standard based on the amount and distribution of ferrite. Levels 1 to 3 are qualified organizations. When the effective hardened layer depth is ≥2.5mm, the core structure does not need to be checked. 3.2.6 Decarburization and soft spots
The surface decarburization, magnetic depletion layer depth and rate tempering soft spots of carburized bearing parts after quenching should not exceed 23 of the single-side wear. 3.2. 7 Cracks
After carburizing heat treatment of carburized bearing parts, cracks are not allowed on the surface. 3.2.8 Ring deformation
The deformation of the ring after carburizing heat treatment should be in accordance with Appendix C (Standard Appendix) or the manufacturer's regulations. 3.2.9 Tempering stability
After quenching and tempering of carburized bearing parts, the maximum hardness difference of the corresponding points after tempering at the original tempering temperature for 3~5h should not be greater than 1HRC. This item does not need to be checked when the effective hardened layer depth is ≥2.5mm. 4 Measurement, inspection and evaluation methods
4.1 Effective carburized hardened layer depth
The effective hardened layer depth can be measured by any of the following methods: hardness method, macro fracture method and microstructure analysis method [see Appendix A (Standard Appendix) 1. In case of dispute, the hardness method shall prevail. 4.2 Hardness
4.2.1 Hardness of forgings
The hardness of forgings or after heat treatment shall be measured in accordance with the provisions of GB/T231. 4.2.2 Surface hardness of carbon parts
The surface hardness of carburized parts shall be measured in accordance with the provisions of JB/T1255. 4.2.3 Core hardness of carburized parts
For tapered roller bearing rings, the measurement shall be at the point 13 ring widths away from the large end face of the ring on the longitudinal section, and for cylindrical roller bearing rings, the measurement shall be at the longitudinal section or the center of the specimen. For cylindrical rollers, the measurement shall be at the center line of the longitudinal section or the center of the cross section 13 lengths from the large end face of the roller. For large parts, the measured excess value at the center of the specimen shall prevail. 3
4.3 Microstructure
JB/T 8881—2001
The microstructure is evaluated at 500 times, and it is also allowed to be evaluated at 450~600 times, but the effect of magnification should be taken into account. The etchant can generally be 4% nitric acid alcohol solution.
4.3.1 The microstructure of the carbonized surface layer shall be based on the first field of view of the surface after the wear amount is removed (or the finished product). 4.3.2 The microstructure of the core shall be based on the microstructure near the core hardness. 4.4 Carbide
4.4.1 Depth of coarse carbide
After the specimen is etched with 4% nitric acid alcohol solution, it shall be measured under a microscope with a magnification of 100 times. It is also allowed to measure at 90~110 times, but the effect of magnification should be taken into account.
4.4.2 Coarse carbides and network carbides
Based on the first visual field of the surface after removing the remaining wear (or finished product), evaluate at 500 times. It is also allowed to evaluate at 450-600 times, but the influence of the magnification factor should be taken into account: deep etching with 4% nitric acid alcohol solution. 4.5 Surface cracks
First, 100% visual inspection shall be carried out. If necessary, rolling elements and rings with an outer diameter of 400mm can be inspected according to Appendix B of JB/T1255-2001 after sandblasting or rough grinding; rings with an outer diameter of >400mm can be inspected by dye penetrant flaw detection [see Appendix B (Standard Appendix)] or other methods that can show surface cracks.
First level
JB 8881—2001
Deep measurement of coarse carbides in carburized layer
Magnification: 100×
First level figure
Coarse carbides in carburized layer
Magnification: 500×
Second level
First level
JB/T 8881—2001
Third level
Second level circle
Network carbides in carburized layer
Magnification: 500×
Second level
Third level
JB 8881—2001
Third level figure
Carburized layer high temperature tempering microstructure
Effective multiple 500×
Level 4
Level 2
Effective stable carbon hardening layer depth <2.5mm
Level 4
JB/T 8881—2001
Level 3
Effective carbon hardening layer depth = 2.5mm
Level 5
Level 1
Level 3
JB/T 8881--2001
Fourth level figure
Carburized layer microstructure after direct carburizing fire
Effective multiple 500×
Rebound 25 Surface cracks
Firstly, 100% visual inspection shall be carried out. If necessary, rolling elements and rings with an outer diameter of 400mm can be inspected according to Appendix B of JB/T1255-2001 after sandblasting or rough grinding; rings with an outer diameter of >400mm can be inspected by dye penetrant testing [see Appendix B (Appendix of the standard)] or other methods that can show surface cracks.
First level
JB 8881—2001
Deep measurement of coarse carbides in carburized layer
Magnification: 100×
First level figure
Coarse carbides in carburized layer
Magnification: 500×
Second level
First level
JB/T 8881—2001
Third level
Second level circle
Network carbides in carburized layer
Magnification: 500×
Second level
Third level
JB 8881—2001
Third level figure
Carburized layer high temperature tempering microstructure
Effective multiple 500×
Level 4
Level 2
Effective stable carbon hardening layer depth <2.5mm
Level 4
JB/T 8881—2001
Level 3
Effective carbon hardening layer depth = 2.5mm
Level 5
Level 1
Level 3
JB/T 8881--2001
Fourth level figure
Carburized layer microstructure after direct carburizing fire
Effective multiple 500×
Rebound 25 Surface cracks
Firstly, 100% visual inspection shall be carried out. If necessary, rolling elements and rings with an outer diameter of 400mm can be inspected according to Appendix B of JB/T1255-2001 after sandblasting or rough grinding; rings with an outer diameter of >400mm can be inspected by dye penetrant testing [see Appendix B (Appendix of the standard)] or other methods that can show surface cracks.
First level
JB 8881—2001
Deep measurement of coarse carbides in carburized layer
Magnification: 100×
First level figure
Coarse carbides in carburized layer
Magnification: 500×
Second level
First level
JB/T 8881—2001
Third levelwww.bzxz.net
Second level circle
Network carbides in carburized layer
Magnification: 500×
Second level
Third level
JB 8881—2001
Third level figure
Carburized layer high temperature tempering microstructure
Effective multiple 500×
Level 4
Level 2
Effective stable carbon hardening layer depth <2.5mm
Level 4
JB/T 8881—2001
Level 3
Effective carbon hardening layer depth = 2.5mm
Level 5
Level 1
Level 3
JB/T 8881--2001
Fourth level figure
Carburized layer microstructure after direct carburizing fire
Effective multiple 500×
Rebound 2
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