This standard specifies the metallographic inspection and evaluation method for cylinder liners of internal combustion engines with a boron content of 0.35% to 0.08%. This standard is applicable to the inspection of the metallographic structure of cylinder liners of internal combustion engines with a cylinder diameter less than or equal to 160mm. JB/T 5082-1991 Metallographic inspection of boron cast iron cylinder liners for internal combustion engines JB/T5082-1991 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
JB/T 5082--91
Boron Cast Iron Cylinder Liner for Internal Combustion Engines
Published on July 1, 1991
Metallographic Inspectionbzxz.net
Implementation on July 1, 1992
Published by the Ministry of Machinery and Electronics Industry of the People's Republic of China
Metallographic Inspection of Boron Cast Iron Cylinder Liner for Internal Combustion Engines
1 Subject Content and Scope of Application
JB/T5082--91
This standard specifies the metallographic inspection and evaluation methods for cylinder liners of internal combustion engines with a boron content of 0.035% to 0.08%. This standard applies to the inspection of the metallographic structure of cylinder liners of internal combustion engines with a cylinder diameter less than or equal to 160mm. 2 Reference standards
GB7216 Grey cast iron metallography
3 Technical requirements
3.1 Graphite
According to GB7216, the graphite shape should be type A, type B, type D, and a small amount of type E is allowed, with a large dispersion and uniform distribution. According to the first level diagram of this standard, it is qualified for levels 1~~4.
3.1.1 Graphite length: When the wall thickness of the finished cylinder liner is less than or equal to 5mm, the graphite length should be less than or equal to 200um. When the wall thickness of the finished cylinder liner is greater than 5mm, the graphite length should be less than or equal to 230um. 3.1.2 Type E graphite: The amount of type E graphite should be less than or equal to 30%. 3.2 Hard phase
Hard phase should be a boron-containing composite or boron carbide, and a small amount of phosphorus eutectic precipitated separately is allowed, but the total amount of phosphorus eutectic in the boron-containing composite and the phosphorus eutectic precipitated separately should be less than or equal to 40% of the total area of ​​hard phase in the field of view. 3.2.1 Distribution and quantity of hard phase
Hard phase should be discontinuous network or dispersed, evenly distributed, and no serious segregation or severe dendrites are allowed. 3.2.1.1 Distribution and quantity of hard phase
When the hard phase is distributed in a mesh, the mesh diameter should be less than or equal to 350μm, and the quantity of hard phase should be greater than 6% of the field of view area. According to the second level diagram of this standard, it is evaluated: 1 to 3 levels are qualified. 3.2.1.2 When the hard phase is distributed in an aggregated or dendritic shape, it is evaluated according to the third level diagram of this standard: 1 level is qualified. 3.2.2 Size of hard phase
When the hard phase is dispersed, its single block area should be less than or equal to 8000μm, and it should be qualified according to the fourth level diagram of this standard: 1~2 levels are qualified.
3.2.3 Composition of hard phase
The composition of hard phase should be mainly boron carbide, and it should be qualified according to the fifth level diagram of this standard: 1~2 levels are qualified. 3.2.4 Boron-containing cementite and ledeburite
A small amount of cementite and ledeburite is allowed in the hard phase, among which the number of cementite should be less than or equal to 7% of the viewing area, the number of ledeburite should be less than or equal to 11% of the viewing area, and the total amount of cementite and ledeburite should be less than or equal to 14% of the viewing area. The single block area of ​​cementite should be less than or equal to 1000uμm2, and the single block area of ​​ledeburite should be less than or equal to 2000μm2, and it should be qualified according to the sixth level diagram of this standard: 1 level is qualified.
3.3 Matrix structure
Approved by the Ministry of Machinery and Electronics Industry on July 1, 1991 and implemented on July 1, 1992
JB/T5082-91
The matrix structure should be pearlite, with a small amount of free ferrite allowed, the amount of which should be less than or equal to 5% of the viewing area. According to the seventh level diagram of this standard, it is evaluated as: 1 to 3 levels are qualified.
Testing method
4.1 Sampling position
When the piston ring is at the top dead center, the longitudinal section between 5mm above and 15mm below the center of the first piston ring groove should be used as the metallographic grinding surface, and the sample should be cut within 1mm of the working surface. 4.2 Evaluation method
4.2.1 The graphite distribution shape is selected by selecting the worst viewing field on the grinding surface, but if three viewing fields of graphite length and E-type stone are unqualified, it is unqualified. The length of the stone wall is calculated as the straight-line distance between the two ends of a single graphite. If there are three excessively long graphite lines in a single field of view, the field of view is unqualified.
Qualified.
The distribution, quantity and composition of the hard phase are evaluated by the majority of the fields on the grinding surface. If three consecutive fields of view are unqualified, it is considered unqualified. The distribution and size of the hard phase in the form of mulberry and dendrite, cementite, ferrite, etc. are evaluated by the worst field on the grinding surface. The evaluation of the stone is carried out on the unetched sample. For the evaluation of the hard phase and matrix structure, the sample is etched with 2% to 4% nitric acid alcohol solution.
4.2.5 The diameter of the image size of this standard is 70mm. 5 Rating of metallographic structure
5.1 Rating of graphite
Graphite is evaluated according to the first-level diagram at a magnification of 100 times. The description of each level is shown in Table 1. Table 1
Type A graphite, uniform distribution
Type B graphite, uniform distribution
Type D graphite
Type D and E graphite, E graphite ≤30%
Type D and E graphite, E graphite>30%
Coarse type A graphite
5.2 Rating of hard phase distribution and quantity
The distribution and quantity of the hard phase are evaluated according to the second level diagram under a magnification of 100 times. The description of each level is shown in Table 2. Table 2
Distribution
and quantity of hard phase
Fine intermittent mesh distribution (mesh diameter ≤ 150μm)Uniformly dispersed distribution (number> 10%)
Medium intermittent mesh distribution (150um<mesh diameter ≤ 250μm)Uniformly dispersed distribution (8%<number≤ 10%)Large intermittent mesh distribution (250um<mesh diameter ≤ 350μm)Uniformly dispersed distribution (6%<number≤ 8%)
Large intermittent mesh distribution (mesh diameter> 350μm)Dispersed distribution (number≤ 6%)|| tt||5.3 Rating diagram for the distribution of hard phase in aggregated and dendritic form
The distribution of hard phase in aggregated and dendritic form is rated according to the third level diagram when magnified 100 times, and the descriptions of each level are shown in Table 3. 2
Rating of hard phase size
JB/T5082--91
The hard phase is partially aggregated
The hard phase is partially crystalline
The hard phase is severely aggregated
The hard phase is severely crystalline
The size of the hard phase is rated according to the fourth level diagram when magnified 500 times, and the descriptions of each level are shown in Table 1. Table 1
Small block (single block area <4000um)
Medium block (single block area 400080001m) Large block (single block area>8000μm))
5.5 Rating of composition of boron-containing complexes
The composition of boron-containing complexes is evaluated according to the fifth level diagram under magnification of 500 times, and the description of each level is shown in Table 5. Table 5
Composition of boron-containing complexes
Mainly ketone-containing carbides
Boron-containing carbides and phosphorus eutectics
Mainly phosphorus eutectics
5.6 Rating of boron-containing cementite and ledeburite
Boron-containing cementite and ledeburite are evaluated according to the sixth level diagram under magnification of 500 times, and the description of each level is shown in Table 6. Table 6
A small amount of cementite (quantity ≤ 7%, single piece area ≤ 1000μm2)
A small amount of ledeburite (quantity ≤ 14%, single piece area ≤ 2000μm2)A large amount of cementite (quantity > 7%, single piece area > 1.000μm2)A large amount of ferrite (quantity > 14%, single piece area > 2000μm2)Rating of free ferrite in the matrix
The free ferrite in the matrix is ​​evaluated according to the seventh level diagram under a magnification of 500 times. The description of each level is shown in Table 7. Table 7
Ferrite ≤2
Ferrite ≤3
Ferrite ≤5
Ferrite>5
Rat (%)
JB/T5082—91
Grade diagram (100×)
Figure 71a grade
Figure 92a grade
Figure 113a grade
JB/T5082—97
Second grade diagram (100×)
Figure 81b grade
Figure 102b.Level
Figure 123 Levelb
Figure 134 Levela
Figure 151a Level
Figure 172a Level
JB/T5082—91
Third level diagram (100×)
Figure 14 Level
Figure 161 Levelb
Figure 1826 Level
Figure 191 Level
JB/T50 82—91
Fourth level diagram (500×)
Diagram 213 level
Fifth level diagram (500×)
Diagram 202 level
Diagram 232 level
Diagram 272a level
JB/T5082—91
Diagram 243 level
Sixth level diagram (500×)
Diagram 282b level
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