JB/T 8569-1997 This standard is a revision of JB/CQ/T 131-91 "Technical Conditions for Carburizing Heat Treatment of Carbon Steel Balls" and is formulated for the first time as an industry standard. This standard specifies the technical requirements, inspection methods and inspection rules for carburizing and quenching and tempering of carbon steel balls made of 10 and 15 high-quality carbon structural steels or carbon steels with carbon content and mechanical properties close to those of GB 699 "Technical Conditions for High-quality Carbon Structural Steels". This standard is applicable to the quality inspection of carburizing heat treatment of carbon steel balls. For carbon steel balls with special requirements, the quality of carburizing heat treatment shall be implemented in accordance with the relevant provisions of the product drawings. JB/T 8569-1997 Technical Conditions for Carburizing Heat Treatment of Carbon Steel Balls for Rolling Bearing Parts JB/T8569-1997 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
JB/T8569—1997
Rolling Bearing Parts
Technical Conditions for Carburizing Heat Treatment of Carbon Steel Balls
1997-04-15 Issued
Ministry of Machinery Industry of the People's Republic of China
1998-01-01 Implementation
JB/T8569—1997
This standard is a revision of JB/CQ/T131-91 "Technical Conditions for Carburizing Heat Treatment of Carbon Steel Balls". It is formulated for the first time as an industry standard. This standard mainly revises the carburizing core hardness and carburizing microstructure of carbon steel balls in the original standard, and supplements the correction value of carbon steel ball surface hardness and the test specifications for crushing and loading drugs of carbon steel balls. Appendix A, Appendix B, Appendix C and Appendix D of this standard are all standard appendices. This standard was proposed and managed by the National Technical Committee for Rolling Bearing Standardization. The drafting units of this standard are: Machinery Industry Bureau Yang Bearing Research Institute, Chuandong Steel Ball Factory. The main drafters of this standard are: Yang Qiaoling, Wang Jiejun, Li Suhua. 1 Scope
Machinery Industry Standard of the People's Republic of China
Rolling Bearing Parts
Carbon Steel Ball Carburizing Heat Treatment Technical Conditions
JB/T 8569-1997
This standard specifies the carburizing and tempering technical requirements, inspection methods and inspection rules for carbon steel balls made of 10.15 high-quality carbon steel structural steel or carbon steel with carbon content and mechanical properties close to that of GB6996 "Technical Conditions for High-quality Carbon Structural Steel". This standard is applicable to the quality inspection of carbon steel balls carburizing heat treatment. Carbon steel balls with special requirements should be subject to the relevant provisions of the product drawings.
Cited Standards
The texts 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 the parties using this standard should explore the possibility of using the latest versions of the following standards. GB 224-87
GB 230-91
GB 699-88
GB 181879
GR 9450--88
JB 1255—91
3 Technical requirements
Surface carbon contentbZxz.net
Method for determining the depth of decarburized layer of steel
Method for testing Rockwell hardness of metal
Technical conditions for high-quality carbon structural steel
Method for testing Rockwell hardness of metal surface
Determination and verification of carburization rate and effective hardening layer depth of steel parts Heat treatment technology of high carbon chromium bearing steel rolling bearing parts Carburization quality of parts The surface carbon content of saw ball should be 0.8%~1.05%. 3.2 Hardness
3.2.1 The surface hardness after carburizing and tempering shall not be less than 62HRC. The surface hardness of the tempered sheet shall not be less than 60HRC. 3.2.2 The core hardness shall not be less than 20HRC. 3.2.3 The difference in surface hardness of the same steel ball shall not be less than 2.0HRC. 3.3 Effective hardened layer depth
The effective hardened layer depth of the steel ball shall comply with the provisions of Item 1. Table 1
Nominal diameter of copper ball
Approved by the Ministry of Machinery Industry on April 15, 1997
Minimum depth of effective hardened layer
Implemented on January 1, 1998
3.4 ​​Microstructure
Nominal diameter of steel ball
JB/T8569-1997
Minimum depth of effective hardened layer
3.4.1 The microstructure of the surface layer after carburizing and tempering shall be composed of martensite and carbide. The coarse needle wustene structure shall not be greater than the provisions of Figure 1.
3.4.2 When the hardness of the surface layer is qualified, the existence of flexure is allowed: the core structure is not controlled. 3.4.3 The network carbide of the carburized layer shall not exceed the provisions of Figure 2. Figure 1 Body structure 500×
3.5 Cracks
No cracks are allowed after carburizing and tempering of steel balls. 3.6 Decarburization layer
The depth of decarburization layer on the surface of steel balls after heat treatment should not be greater than 2/3 of the single-side reserve. 3.7 Crushing load of steel balls
The crushing load value of steel balls after quenching and tempering and finished products should not be less than the requirements in Table 2. 2
Figure 2 Network carbide 500×
Nominal diameter
Inspection method and inspection rules
4.1 Hardness test
JB/T 856#—1997
2. Crushing load of steel ball
Crushing load
Nominal diameter
11:112
4.1.1 The Rockwell impact strength and surface Rockwell hardness shall be measured in accordance with the provisions of GB230 and GB1818 respectively. Positive load
4.1.2 The hardness of a steel ball with a diameter of 4.7625mm (3/16in) to 15.8750mm (5/8in) is measured on the spherical surface, and the hardness correction value of the curved surface is added according to the provisions of Appendix A (Standard Appendix). 4.1.3 The determination of the hardness of the core of the saw ball between processes and finished products should be carried out on the ground plane. 4.2 Effective hardening layer depth measurement
The effective hardening layer depth measurement is carried out according to any method specified in Appendix B (Standard Appendix). If there is a difference, the degree determination method shall prevail.
4.3 Microscopic group observation
The microstructure of the surface layer of the steel ball should be evaluated at 500 times, and it is also allowed to be carried out at 450-600 times-but the magnification should be taken into account. The etching agent is 2% to 4% nitric acid alcohol solution. 4.4 Determination of decarburization
The depth of the decarburized layer on the surface of the ball The measurement is in accordance with the provisions of GB224. 4.5 Crack inspection
Ball cracks shall be inspected in accordance with the cold pickling inspection procedures specified in JB1255. In case of objection, the hot pickling method specified in Appendix C (Appendix to the standard) shall prevail.
4.6 Steel ball crushing load test
The steel ball crushing load test after tempering and finished product shall be carried out in accordance with the provisions of Appendix D (Appendix to the standard). 3
A1 See Table A1 for the correction value of the spherical surface of the steel ball. Nominal diameter of the steel ball
JB/T 8569-1997
Appendix A
(Standard Appendix)
Correction value of spherical hardness of steel ball
4.714.5 4. 3
3.7 3. 5 3. 53. 12. 9
3.3 3.1:2.92.72.52.2
3.33.12.9 2.8 2.62.42.22.0
3.02. 92.7 2. 5 2. 32. 22. 0|1. 8282625232,1201.81.7
2. 62. 42. 3 2.1, 2. 01. 81. 61. 52. 715
2. 52.2. 22. 1 1. 9 1. 81. 61. 5/1. 32. 12. 22. 11. 9*1. 8- 1. 61. 51. 3; 1. 21. . 2 1.10. 92. 12. 01. 8|1. 7:1. 6;1:41. 31. 2;1. 00. 82. 01. 51. 71. 6,1. 5;1. 31. 21.1. 0. 50. 82. 01. 61. 61. 5 1. 4: 1. 21. 11. 0:0. 80. 71.91.71. 61.5 1. 3 1.21.10, 90. 80. 61. 7[1. 61. 51. : 1. 2 1.10. 90. 80, 70. 51.41.31.2:1.10.90.80.70.50.41,6
1.31. 21. 00. 0.80. 70. 50. 40. 31.4
1.21.110.90.80.70.50.40.30.213
Fractography method
Crush the steel ball and crack it.
JB/T 8569—1997
Appendix B
(Appendix of the standard)
Effective hardened layer depth measurement method
B1.2 Observe the fracture surface. The carburized layer is white porcelain-like, and the uncarburized part is gray fiber-like. The carbon content at the junction of the two parts is about 0.4%. Note: To increase the visibility of the carburized layer, the fracture surface can be heated in a 2GU air furnace for 13~15min so that the carburized layer is dyed golden yellow while the core color is not porcelain. Use a low-power engraving magnifier to measure the effective hardened layer depth. B2 Microstructure method
On a microscope, observe the surface layer structure of the cross section of the corrosion sample, and measure the depth from the surface to half of the over-plating layer, which is the depth of the effective hardened layer E2.1
.
2.2 The effective hardened layer depth should include the sum of the depth of the hypereutectoid layer-eutectoid layer + 1/2 transition layer. Feng
1 Applicable to the measurement of carburized layers with eutectoid layers greater than the total depth: 2 The sample is preferably measured in the quenching state.
Hardness determination method
The determination of the effective hardened layer depth by steel ball penetration quenching shall be in accordance with the provisions of GB 9450. The radial depth measured from the surface to the point where the hardness value is 550HV under a load of 9.8N is the depth of the effective penetration hardened layer. 5
JB/T 8569-1997
Appendix C
(Appendix of the mark)
Hot pickling inspection procedure
This procedure applies to the crack inspection of bearing parts after tempering. The parts should be sandblasted or degreased before pickling. The pickling liquid is 50% hydrochloric acid aqueous solution, the temperature is 60℃±5℃. The pickling time is 10~30min. The parts after hot etching can be neutralized with 4%-6% sodium carbonate aqueous solution at room temperature. The time is about 1min. C3
C4 Observe the surface of the pickled parts with naked eyes. 6
J1/18569—1997
Appendix D
(Appendix to the standard)
Steel ball crushing load test procedure
This procedure specifies the crushing load test of saw balls with a nominal diameter of 3~50mm. D1 Three groups of balls (9 balls) are taken from each batch of heat-treated steel balls for steel ball crushing quality inspection. The size tolerance of the balls should be consistent: D2 When the heat-treated flat finished balls are subjected to the crushing test, the steel ball surface is not allowed to have visible grinding wheel scratches, pits, bumps and pitting and other surface defects.
D3 When the steel ball crushing load test is performed, the loading speed can be 980~5880N/s. D4 The load applied to the steel ball has exceeded the standard. Although the steel ball is not crushed, the load can be unloaded. If there are special requirements, the steel ball can be loaded until it is crushed.
D5 Remove the ball pressing jig from the testing machine, open the safety cover, and quickly take out the ball and throw it into the iron box with a cover to prevent the steel ball from exploding and injuring people, and then record the test results.
D6 During the test, if the ball falls off due to improper placement or cracks in the ball, resulting in inaccurate results, the result should be corrected and reconnected for testing.
D7 During the test, the ball crushing load reaches or exceeds the specified standard requirements. When the load is removed, the ball is crushed. This result is treated as qualified. D8 During the test, the loading speed shall not be changed suddenly and the load shall not be removed in the middle. When the steel ball is crushed, some testing machines vibrate greatly, and the pointer jumps, making the reading incorrect. Therefore, attention should be paid to the load number when the steel ball is crushed.
110 The crushing jig is designed according to the size of the ball. The crushing jig angle is 90°. The jig can be made of carbon tool steel or bearing steel. The hardness after rate reduction is required to be 60~65 IRC. 7
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