JB/T 8837-2000 JB/T 8837-2000 Metallographic inspection of connecting rod bolts for internal combustion engines JB/T8837-2000 Standard download decompression password: www.bzxz.net

ICS 27.020
Machinery Industry Standard of the People's Republic of China
JB/T 8837--2000
Internal combustion engines
Connecting rod bolts-Metallographic examination
Published on April 24, 2000
State Bureau of Machinery Industry
Implemented on October 1, 2000
JB/F 8837-2000
This standard is a revision of JB/F8837-1999 (Metallographic Inspection of Connecting Rod Bolts for Internal Combustion Engines). During the revision, editorial changes were made to the original standard, and the main technical content remained unchanged. This standard replaces JB/T8837-1999 from the first implementation. This standard is not proposed and managed by the National Technical Committee for Standardization of Internal Combustion Engines. The drafting unit of this standard is Shanghai Internal Combustion Engine Research Institute. The main drafter of this standard is Du Rong.
This standard was first issued on July 25, 1983 as NJ309--83, and the standard number was adjusted to JBT8837-1999 in April 1999.
Mechanical Industry Standard of the People's Republic of China
Metallographic Inspection of Connecting Rod Bolts for Internal Combustion Engines
Internal eombustion eliginesConnceting rod bolts-Metallographic examination
This standard specifies the technical requirements, inspection methods and metallographic structure of internal combustion engine connecting rod bolts. B/T8837-2000
Replaces JB/T8837-1999
This standard specifies the metallographic structure inspection of internal combustion engine connecting rod bolts made of F40Cr, 35CrMaA, 15MnB, 15MnVB, 20MnV and other steels after heat treatment:
2 Technical requirements
2.1 The material and hardness of the internal combustion engine connecting rod bolts shall comply with the provisions of the product sample. 2.2 The connecting rod bolts made of 40Cr, 35CrMoA and other steels shall be inspected. 2.2.1 The matrix structure of hot forged connecting rod bolts after quenching and tempering should be tempered troostite, and a small amount of ferrite is allowed. Its content should not exceed 3%. According to the first level diagram of this standard, it is qualified for levels 1 to 3. 2.2.2 The matrix structure of connecting rod bolts after spheroidizing annealing and cold treatment should be tempered troostite after quenching and tempering. A small amount of undissolved granular carbide is allowed. Its content of undissolved granular carbide is evaluated according to the second level diagram of this standard, and it is qualified for levels 1 to 3. 2.3 The matrix structure of connecting rod bolts made of 15MnB, 15MnVB, 20MnV and other steels is allowed to have a small amount of ferrite, and its content should not exceed 3%. According to the third level diagram of this standard, it is qualified for levels 1 to 3. 3 Inspection method
3.1 Take a sample of the transverse section at a distance of 1.5 times the bolt diameter from the end of the thread as the metallographic grinding surface: 3.2 The sample is etched with 2%-5% dichloroacetic acid alcohol
3.3 Observe at a magnification of 500 times, and take the worst visual field as the basis for evaluation. 4 Metallographic structure rating standard
The first level rating description is shown in Table 1.
Approved by the State Machinery Industry Bureau on April 24, 2000 Microstructure description
No free defect body
With micro ferrite
With a small amount of ferrite
With more ferrite
With large plaque ferrite
Drawing number country
2000-10-01 implementation
The second level rating description is shown in Table 2.
Grade description of the first level diagram is shown in Table 3
JB/T 8837—2000
Microstructure description
No dissolved viscous carbide
With slightly dissolved granular carbide
With a small amount of partially dissolved granular carbide
With a large amount of dissolved granular carbide
Microstructure description
No free ferrite
With trace ferrite
With a small amount of parent ferrite
With more ferrite
With a large amount of ferrite
First level diagram (500×)
Grade 22
Figure 44
JB/T 8837-2000
Figure 33rd level
Figure 55th level
Figure 61st level
Figure 83rd levelbzxz.net
JB/ 8837-2000
Figure 72nd level
Figure 94th level
Figure II1st level
JB/T 8837—2000
Figure 105th level
Third level figure (500×)
Figure 122nd level
Figure 133rd level
JB/T 8837-2000
Figure 155th level
Figure 144th level
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