JB/T 1255—2001 This standard is a revision of JB/T 1255—1991 "Technical Conditions for Heat Treatment of High Carbon Chromium Bearing Steel Rolling Bearing Parts". The scope of application was expanded during the revision; some technical provisions were modified. This standard specifies the technical requirements for annealing, quenching and tempering of GCr15, GCr15SiMn, GCr15SiMo, GCr18Mo steel rolling bearing parts, as well as inspection procedures such as steel ball crushing load, cold and hot pickling, and magnetic flaw detection. This standard is applicable to the heat treatment quality inspection of the above-mentioned steel bearing parts between processes and finished parts. For bearing parts with special requirements, the corresponding standards and product drawings shall be followed. This standard was first issued in 1972, revised for the first time in 1981, revised for the second time in 1991, and this is the third revision. JB/T 1255-2001 Technical conditions for heat treatment of rolling bearing parts made of high carbon chromium bearing steel JB/T1255-2001 Standard download decompression password: www.bzxz.net

ICS21.100.20
Machinery Industry Standard of the People's Republic of China
JB/T1255-2001
Specification for heat-treatment of rolling bearing parts madefromhighcarbonchromium steel2001-05-23Promulgated
China Machinery Industry Federation
2001-10-01Implementation
JB/T1255-2001
1Scope
2Referenced standards
Technical requirements for bearing parts
4Testing methods
Appendix A (Appendix to the standard) Steel ball crushing load test procedure and crushing load valueAppendix B (Appendix to the standard) Magnetic flaw detection test procedureAppendix C (Appendix to the standard) Acid Cleaning and testing procedures, Appendix D (Standard Appendix) Surface hardness correction value and hardness conversion table Appendix E (Suggestive Appendix) Depth of decarburized layer after quenching and tempering of bearing parts: Appendix F (Suggestive Appendix) Allowable deformation of bearing rings after quenching and tempering Appendix G (Suggestive Appendix) Provisions for effective wall thickness of rings and effective diameter of rollers 13
JB/T1255-2001
This standard is a revision of JB/T1255--1991 "Technical Conditions for Heat Treatment of High Carbon Chromium Bearing Steel Rolling Bearing Parts". Compared with JB/T1255-1991, this standard has made the following changes: - The scope of application has been expanded, and new steel grades GCr15SiMn and GCr18Mo have been added; - Different hardness and structure requirements have been proposed for bearing parts of different size segments and different performance requirements; - The relevant clauses of "Technical conditions for special bearing parts" have been deleted; - The "Recommended technical requirements for bainite isothermal quenching or graded quenching bearing parts" have been revised and listed as the formal provisions of this standard;
- The provisions for calculating the effective wall thickness of bearing rings and the effective diameter of rollers have been added; - The arrangement of the content has been modified. This standard replaces JB/T1255-1991 from the date of implementation. Appendix A, Appendix B, Appendix C and Appendix D of this standard are all appendices to the standard. Appendix E, Appendix F and Appendix G of this standard are all indicative appendices. This standard is proposed and managed by the National Technical Committee for Standardization of Rolling Bearings. Drafting units of this standard: Luoyang Bearing Research Institute, Wanxiang Group Corporation. The main drafters of this standard are Liu Yaozhong, Zhang Zengqi, Lei Jianzhong, Guo Zengjun, Pan Yu, Huang Chunxiao and Fan Zhiqiang. This standard was first issued in 1972, revised for the first time in 1981, revised for the second time in 1991, and this is the third revision. 1
Mechanical Industry Standard of the People's Republic of China
High Carbon Chromium Bearing Steel Rolling Bearing Parts
Technical Conditions for Heat Treatment
Specificationforheat-treatmentof rolling bearingparts madefrom high carbon chromium steel1Scope
JB/T1255-2001
Replaces JB/T1255—1991
This standard specifies the technical requirements for annealing, quenching and tempering of rolling bearing parts made of GCr15, GCr15SiMn, GCr15SiMo and GCr18Mo steels, as well as the inspection procedures for steel ball crushing load, hot and cold pickling, magnetic flaw detection, etc. This standard applies to the heat treatment quality inspection of the above steel bearing parts between processes and finished parts. Bearing parts with special requirements should be in accordance with the provisions of the corresponding standards and product drawings. 2 Reference standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T231—1984
GB/T15822-1995
JB/T2974-1993
JB/T 7361-1994
JB/T7362—1994
YB/T5148—1993
3 Technical requirements for bearing parts
Metal Brinell hardness test method
Magnetic particle inspection method
Supplementary provisions for rolling bearing code method
Hardness test method for rolling bearing parts
Decarburization layer inspection method for rolling bearing parts
Method for determining average grain size of metal
3.1 Technical requirements for bearing parts after annealing
The technical requirements for bearing parts after annealing shall be in accordance with the provisions of Table 1. Table 1 Technical requirements after spheroidizing annealing
Inspection items
Microstructure
Network carbide
Decarburization layer depth
Technical requirements
Other steel types
179~217HB (indentation diameter 4.5~4.1mm) or 88~97HRB179~207HB (indentation diameter 4.5~4.2mm) or 88~94HRB Small, evenly distributed spheroidized group The organization is evaluated according to the first level diagram: 2~4 levels are qualified organizations, fine point spheroidization organization is allowed, and 1 (underheating), 5 (uneven carbide hooking) and 6 (overheating) organizations are not allowed. According to the fourth level diagram, the organization is evaluated: no more than 2.5 is qualified and no more than 2/3 of the minimum machining allowance on one side
1 The hardness of bearing parts after annealing after special processing such as cold extrusion or refinement treatment should not be greater than 229HB (indentation diameter is not greater than 4.0mm). 2 Other steel types refer to GCr15SiMn, GCr15SiMo and GCr18Mo. Approved by China Machinery Industry Federation on May 23, 2001, implemented on October 1, 2001
JB/T1255—2001
3.2 Technical requirements for bearing parts after martensite quenching and tempering3.2.1
The hardness of bearing parts after martensite tempering and the hardness difference of the same parts shall be in accordance with the provisions of Table 2 and Table 3 respectively. Table 2 Hardness of bearing parts after martensite quenching and tempering Finished product size
After quenching
After tempering
200℃
Hardness after conventional tempering
Hardness after high temperature tempering
250℃
Hardness after conventional tempering
Hardness after conventional tempering
1 The provisions of the effective wall thickness of the ring and the effective diameter of the roller in the table are shown in the attached Record G (Appendix of Prompt) 300℃
350℃
400℃
2 The high temperature tempering temperatures in the table are 200℃, 250℃, 300℃, 350℃, 400℃ and the hardness requirements after tempering. Their codes correspond to SO, S1, S2, S3, S4 in JB/T2974 respectively; for rolling elements with "hardness after conventional tempering", high temperature tempering can also be performed when there are special requirements. 3 For the division of size segments in the table and the corresponding hardness requirements, manufacturers and users can specify them according to the working conditions and performance requirements of the bearings. Table 3 Hardness difference of the same part of bearing parts after martensitic quenching and tempering Part name
Finished product size
Hardness difference max
Ring (outer diameter)
Note: The provisions of the effective diameter of the roller in the table are shown in Appendix G. 400
Rolling element (effective diameter)
Miniature bearing parts
Not inspected
3.2.2 The microstructure of bearing parts after martensite quenching and tempering shall be composed of cryptocrystalline, fine crystalline martensite, evenly distributed fine residual carbides, a small amount of retained austenite and a small amount of temite. The microstructure requirements after quenching and tempering shall be in accordance with the provisions of Table 4. 2
All tolerance levels
JB/T1255—2001
Table 4 The structure of bearing parts after martensite quenching and tempering Finished size
Effective wall thickness of ring
Steel ball diameter
Miniature bearings
(Grade 3,5,10)
Effective roller diameter
（0.1 grade)
Organization level
Mortensitic
Martensite
Within 3mm from working surface
t~3 grade
1~5 grade
1~5 grade
Beyond 3mm from working surface
Not allowed
1~2 grade
1~2 grade
1~5 grade
1~2 grade
1~5 grade
1~2 grade
1~2 grade
Not controlled
1All steel grades refer to GCr15, GCr15SiMn, GCr15SiMo and GCr18Mo, and other steel grades refer to GCr15SiMn, GCr15SiMo and GCr18Mo. 2 The provisions of the effective wall thickness of the ring and the effective diameter of the roller in the table are shown in Appendix G. Other technical requirements for bearing parts after quenching and tempering shall be in accordance with the provisions of Table 5. 3.2.3
Table 5 Other technical requirements for bearing parts after quenching and tempering Inspection items
Steel ball crushing load
Tempering stability
Decarburization and soft spots
Ring deformation
After quenching and tempering, no cracks are allowed in bearing parts Technical requirements
The crushing load value of the steel ball after quenching and tempering shall not be less than the provisions of Table A1 and Table A2 in Appendix A (Standard Appendix) Tempering stability must be ensured after quenching and tempering of bearing parts. Tempering stability refers to the maximum hardness difference of the corresponding points before and after the second tempering of the tested parts. The hardness difference is not more than 1HRC. If there is any objection to the quality of heat treatment after tempering, the fracture test can be carried out. The fracture should be light gray fine porcelain. Level 2 is qualified. Level 1 underheating or level 3 overheating fracture is not allowed. The depth of decarburization layer (or surface soft spot) between processes should comply with the regulations of the manufacturer or the provisions of Appendix E (Suggested Appendix), but the finished product is not allowed to have decarburization or soft spots.
The deformation of the bearing parts after tempering shall be in accordance with the provisions of Appendix F (Suggested Appendix) or the regulations of the manufacturer. 3.3 Technical requirements for bainite after isothermal quenching of bearing parts. The bainite isothermal quenching organization consists of bainite, retained carbides and a small amount of troostite. The hardness and organization of bainite after isothermal quenching of bearing parts shall be in accordance with the provisions of Table 6, and other items not listed shall be in accordance with the provisions of Table 5. Steel type
GCr18Mo
JB/T1255—2001
Table 6 Hardness and structure of bearing parts after austempering Ring effective wall thickness
Note: The provisions of the effective wall thickness of the ring in the table are shown in Appendix G. Inspection method
The inspection method shall be in accordance with the provisions of Table 7.
Inspection items
Bainite
1~3 levels
Table 7 Inspection methods and procedures
Troussite
Within 3mm from the working surface
1~2 levels
1~5 levels
1~2 levels
[~5 levels
Inspection methods and procedures
Beyond 3mm from the working surface
Not controlled
Grain size|| The hardness test of grains of grade 8 or finer can be carried out by using Brinell, Rockwell, Vickers or Leeb hardness testers according to the hardness value and size of the workpiece to be tested, and according to the provisions of GB/T Hardness Microstructure Network Carbide Decarburization and Soft Spot Ring Deformation Steel Ball Crushing Load Tempering Stability Austenite Grain Size 231 and JB/T7361. The diameter of the steel ball shall not exceed 15.8750mm, and the diameter of the roller shall not exceed 15mm. The hardness of the measured curved surface shall be measured according to the provisions of Table D1 and Table D2 of Appendix D (Standard Appendix) plus the correction value. The hardness test of the spherical roller is carried out on the end face. When the rolling element diameter or the ring end face width is not greater than 2mm, hardness inspection is not required between processes, but the finished product must be inspected for hardness. The microstructure should be evaluated using a metallographic microscope at 500×, and it is also allowed to be carried out at (450~600)×, but the influence of magnification should be considered. The annealed structure is etched with 2% nitric acid alcohol or 5% picric acid alcohol solution, and evaluated according to the first level diagram according to the size, quantity and shape of the carbides: the tempered structure is based on the longitudinal section and is etched with 2%~4% nitric acid alcohol solution. The martensite structure is evaluated according to the second level diagram according to the coarseness of the martensite and the size and quantity of the residual carbide particles. If the overheated structure cannot be distinguished after annealing, it is allowed to be carried out after tempering; the martensite is evaluated according to its shape, size and quantity according to the third level diagram: the bainite is evaluated according to the coarseness of the bainite and the size, quantity and shape of the residual carbides according to the sixth level diagram. It is evaluated with a metallographic microscope at 500×, and it is also allowed to be carried out at (450~600)×, but the influence of the magnification should be considered. After normal quenching, the specimen is deep etched with 4% nitric acid alcohol solution on the cross section. Cracks are evaluated according to the fourth level diagram. Magnetic flaw detection (see Appendix B (Appendix to the standard)], cold and hot pickling [see Appendix C (Appendix to the standard) 1 and other instruments and methods can be used for inspection. In case of dispute, hot pickling shall prevail. Surface decarburization and soft spots can be inspected by cold pickling (see Appendix C); the inspection method for the depth of the decarburization layer shall be carried out in accordance with the provisions of JB/T7362. When measured by metallographic method, 2% nitric acid or 5% picric acid alcohol solution is used for etching in the annealed state. For hot steel balls, the grinding surface of the specimen should be perpendicular to the ring band; 4% nitric acid alcohol solution is used for etching in the quenched and tempered state. The decarburization layer is based on the deepest depth. For small-sized rings, dial indicators and internal diameter gauges are used. , outside diameter gauge and flatness gauge inspection; large size set drawing with vernier caliper, pipe ruler, feeler gauge inspection according to the provisions of Appendix A
The tested sample or part shall be tempered again according to the tempering process specification specified in the process document, and the hardness difference of the corresponding points before and after tempering shall be checked. The part shall be crushed and the cross section shall be observed, and evaluated according to the fifth level drawing according to the provisions of YB/T5148
Level 2
JB/T1255-2001
First level drawing
Annealed structure
Magnification
Level 1
Level 3
Level 5
JB/T1255--2001
Level 4
Level 63 Technical requirements for bearing parts after isothermal quenching of bainite The isothermal quenching structure of bainite consists of bainite, carbides and a small amount of troostite. The hardness and structure of bearing parts after isothermal quenching shall be in accordance with the provisions of Table 6, and other items not listed shall be in accordance with the provisions of Table 5. Steel type
GCr18Mo
JB/T1255—2001bzxZ.net
Table 6 Hardness and structure of bearing parts after isothermal quenching Ring effective wall thickness
Note: The provisions of the effective wall thickness of the ring in the table are shown in Appendix G. Inspection method
The inspection method shall be in accordance with the provisions of Table 7.
Inspection items
Bainite
1~3 levels
Table 7 Inspection methods and procedures
Troussite
Within 3mm from the working surface
1~2 levels
1~5 levels
1~2 levels
[~5 levels
Inspection methods and procedures
Beyond 3mm from the working surface
Not controlled
Grain size|| The hardness test of grains of grade 8 or finer can be carried out by using Brinell, Rockwell, Vickers or Leeb hardness testers according to the hardness value and size of the workpiece to be tested, and according to the provisions of GB/T Hardness Microstructure Network Carbide Decarburization and Soft Spot Ring Deformation Steel Ball Crushing Load Tempering Stability Austenite Grain Size 231 and JB/T7361. The diameter of the steel ball shall not exceed 15.8750mm, and the diameter of the roller shall not exceed 15mm. The hardness of the measured curved surface shall be measured according to the provisions of Table D1 and Table D2 of Appendix D (Standard Appendix) plus the correction value. The hardness test of the spherical roller is carried out on the end face. When the rolling element diameter or the ring end face width is not greater than 2mm, hardness inspection is not required between processes, but the finished product must be inspected for hardness. The microstructure should be evaluated using a metallographic microscope at 500×, and it is also allowed to be carried out at (450~600)×, but the influence of magnification should be considered. The annealed structure is etched with 2% nitric acid alcohol or 5% picric acid alcohol solution, and evaluated according to the first level diagram according to the size, quantity and shape of the carbides: the tempered structure is based on the longitudinal section and is etched with 2%~4% nitric acid alcohol solution. The martensite structure is evaluated according to the second level diagram according to the coarseness of the martensite and the size and quantity of the residual carbide particles. If the overheated structure cannot be distinguished after annealing, it is allowed to be carried out after tempering; the martensite is evaluated according to its shape, size and quantity according to the third level diagram: the bainite is evaluated according to the coarseness of the bainite and the size, quantity and shape of the residual carbides according to the sixth level diagram. It is evaluated with a metallographic microscope at 500×, and it is also allowed to be carried out at (450~600)×, but the influence of the magnification should be considered. After normal quenching, the specimen is deep etched with 4% nitric acid alcohol solution on the cross section. Cracks are evaluated according to the fourth level diagram. Magnetic flaw detection (see Appendix B (Appendix to the standard)], cold and hot pickling [see Appendix C (Appendix to the standard) 1 and other instruments and methods can be used for inspection. In case of dispute, hot pickling shall prevail. Surface decarburization and soft spots can be inspected by cold pickling (see Appendix C); the inspection method for the depth of the decarburization layer shall be carried out in accordance with the provisions of JB/T7362. When measured by metallographic method, 2% nitric acid or 5% picric acid alcohol solution is used for etching in the annealed state. For hot steel balls, the grinding surface of the specimen should be perpendicular to the ring band; 4% nitric acid alcohol solution is used for etching in the quenched and tempered state. The decarburization layer is based on the deepest depth. For small-sized rings, dial indicators and internal diameter gauges are used. , outside diameter gauge and flatness gauge inspection; large size set drawing with vernier caliper, tube ruler, feeler gauge inspection according to the provisions of Appendix A
The tested sample or part shall be tempered again according to the tempering process specification specified in the process document, and the hardness difference of the corresponding points before and after tempering shall be checked. The part shall be crushed and the cross section shall be observed, and evaluated according to the fifth level drawing according to the provisions of YB/T5148
Level 2
JB/T1255-2001
First level drawing
Annealed structure
Magnification
Level 1
Level 3
Level 5
JB/T1255--2001
Level 4
Level 63 Technical requirements for bearing parts after isothermal quenching of bainite The isothermal quenching structure of bainite consists of bainite, carbides and a small amount of troostite. The hardness and structure of bearing parts after isothermal quenching shall be in accordance with the provisions of Table 6, and other items not listed shall be in accordance with the provisions of Table 5. Steel type
GCr18Mo
JB/T1255—2001
Table 6 Hardness and structure of bearing parts after isothermal quenching Ring effective wall thickness
Note: The provisions of the effective wall thickness of the ring in the table are shown in Appendix G. Inspection method
The inspection method shall be in accordance with the provisions of Table 7.
Inspection items
Bainite
1~3 levels
Table 7 Inspection methods and procedures
Troussite
Within 3mm from the working surface
1~2 levels
1~5 levels
1~2 levels
[~5 levels
Inspection methods and procedures
Beyond 3mm from the working surface
Not controlled
Grain size|| The hardness test of grains of grade 8 or finer can be carried out by using Brinell, Rockwell, Vickers or Leeb hardness testers according to the hardness value and size of the workpiece to be tested, and according to the provisions of GB/T Hardness Microstructure Network Carbide Decarburization and Soft Spot Ring Deformation Steel Ball Crushing Load Tempering Stability Austenite Grain Size 231 and JB/T7361. The diameter of the steel ball shall not exceed 15.8750mm, and the diameter of the roller shall not exceed 15mm. The hardness of the measured curved surface shall be measured according to the provisions of Table D1 and Table D2 of Appendix D (Standard Appendix) plus the correction value. The hardness test of the spherical roller is carried out on the end face. When the rolling element diameter or the ring end face width is not greater than 2mm, hardness inspection is not required between processes, but the finished product must be inspected for hardness. The microstructure should be evaluated using a metallographic microscope at 500×, and it is also allowed to be carried out at (450~600)×, but the influence of magnification should be considered. The annealed structure is etched with 2% nitric acid alcohol or 5% picric acid alcohol solution, and evaluated according to the first level diagram according to the size, quantity and shape of the carbides: the tempered structure is based on the longitudinal section and is etched with 2%~4% nitric acid alcohol solution. The martensite structure is evaluated according to the second level diagram according to the coarseness of the martensite and the size and quantity of the residual carbide particles. If the overheated structure cannot be distinguished after annealing, it is allowed to be carried out after tempering; the martensite is evaluated according to its shape, size and quantity according to the third level diagram: the bainite is evaluated according to the coarseness of the bainite and the size, quantity and shape of the residual carbides according to the sixth level diagram. It is evaluated with a metallographic microscope at 500×, and it is also allowed to be carried out at (450~600)×, but the influence of the magnification should be considered. After normal quenching, the specimen is deep etched with 4% nitric acid alcohol solution on the cross section. Cracks are evaluated according to the fourth level diagram. Magnetic flaw detection (see Appendix B (Appendix to the standard)], cold and hot pickling [see Appendix C (Appendix to the standard) 1 and other instruments and methods can be used for inspection. In case of dispute, hot pickling shall prevail. Surface decarburization and soft spots can be inspected by cold pickling (see Appendix C); the inspection method for the depth of the decarburization layer shall be carried out in accordance with the provisions of JB/T7362. When measured by metallographic method, 2% nitric acid or 5% picric acid alcohol solution is used for etching in the annealed state. For hot steel balls, the grinding surface of the specimen should be perpendicular to the ring band; 4% nitric acid alcohol solution is used for etching in the quenched and tempered state. The decarburization layer is based on the deepest depth. For small-sized rings, dial indicators and internal diameter gauges are used. , outside diameter gauge and flatness gauge inspection; large size set drawing with vernier caliper, tube ruler, feeler gauge inspection according to the provisions of Appendix A
The tested sample or part shall be tempered again according to the tempering process specification specified in the process document, and the hardness difference of the corresponding points before and after tempering shall be checked. The part shall be crushed and the cross section shall be observed, and evaluated according to the fifth level drawing according to the provisions of YB/T5148
Level 2
JB/T1255-2001
First level drawing
Annealed structure
Magnification
Level 1
Level 3
Level 5
JB/T1255--2001
Level 4
Level 6
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.