This standard specifies the inspection and evaluation methods for the metallographic structure of ordinary alloy cast iron barrel cast piston rings. This standard is applicable to the inspection of the metallographic structure of piston rings of reciprocating internal combustion engines with a cylinder diameter less than or equal to 160mm. JB/T 6290-1992 Metallographic inspection of internal combustion engine barrel cast piston rings JB/T6290-1992 Standard download and decompression password: www.bzxz.net

J92 | | tt | | JB |
Metallographic Inspection of the Ministry of Mechanical and Electronic Industry of the People's Republic of China
Implemented on 1993-07-01
Released
Machinery Industry Standards of the People's Republic of China
Metallographic Inspection
Internal combustion engine barrel cast piston rings
1 Subject content and scope of application
This standard specifies the metallographic structure inspection and evaluation methods of ordinary alloy cast iron simplified cast piston rings. JB/T6290—92
This standard is applicable to the inspection of the metallographic structure of piston rings of reciprocating internal combustion engines with a cylinder diameter less than or equal to 160mm. 2 Reference standards
GB7216 Gray cast iron metallography
3 Technical requirements
3.1 Graphite
Graphite should be type A and B of appropriate size, and type D and A small amount of type E. The dispersion is large and the distribution is even. 3.1.1 When the radial thickness of the ring is less than 4.5mm, the stone length is not more than 150um, and the quantity of type E graphite is not more than 20% of the field of view area. According to the first level Picture assessment, grades 1 to 6 are passed. 3.1.2 When the radial thickness of the ring is not less than 4.5mm, the length of the stone should not be more than 180um, and the number of E-type graphite should not be more than 10% of the field of view area. Evaluate according to the first level chart, and grades 1 to 5 are qualified. 3.2 Matrix structure
3.2.1 Phosphorus eutectic distribution
The phosphorus eutectic should be in the shape of a single small block or intermittent mesh, with fine mesh and even distribution, and no serious dendrites are allowed. or severe segregation. Evaluate according to the second level chart, with grades 1 to 4 passing.
3.2.2 Phosphorus eutectic size
The phosphorus eutectic should be in the shape of small blocks. The maximum area of ??a single phosphorus eutectic should not be greater than 2000um, and the maximum chain length should not be greater than 200um. Evaluate according to the third level chart. Passed Level 1~3.
3.2.3 Phosphorus eutectic-carbide composite
The length of the carbide in the composite shall not be greater than 50um, and the area shall not be greater than 500um. It will be evaluated according to the fourth level chart, and Level 1 is qualified. 3.2.4 The number of free ferrite
free ferrite is not greater than 3% of the field of view area. It is evaluated according to the fifth level chart, and level 13 is qualified. 3.2.5 Pearlitewww.bzxz.net
Pearlite should be Soxhlet type pearlite, fine flake pearlite, and needle-like knitting is allowed. It will be evaluated according to the sixth level chart, and grades 1 to 3 will be qualified. 3.2.6 Granular pearlite, free cementite and ledeburite are not allowed to exist. 4 Inspection methods
4.1 Sampling position
The sample should be loaded within 5mm on the left and right opposite the opening of the ring, and its cross section should be used as a metallographic grinding surface. 4.2 Assessment method
4.2.1 Assessment of graphite length
The assessment of graphite length is carried out by selecting the largest graphite in the entire grinding surface. It is calculated based on the linear length of both ends of the graphite. Three graphites are not allowed to exceed Specify size.
The Ministry of Mechanical and Electronic Industry approved the implementation on 1993-07-01 on 1992-06-10
1
Evaluation of 4.2.2E type stone feel
JB/T6290—92
E-type graphite should be carried out by selecting the worst field of view on the working surface layer of the ring (that is, within the area 1mm from the outer cylindrical surface and the upper and lower end surfaces). If 3 fields of view are unqualified, it is considered unqualified. , and indicate the average percentage content of E-type stone. 4.2.3 Evaluation of graphite distribution shape
The distribution shape of graphite should be based on the comparison pictures of the majority of the stones occupying the entire grinding surface. 4.2.4 Evaluation of the matrix structure
After the matrix structure is etched with 2% 4% nitric acid alcohol, the worst field of view of pearlite, phosphorus eutectic and iron body on the entire depression surface is selected for evaluation. If there are 3 Unsatisfactory results in one field of view are considered unqualified, and the presence of free cementite and ledeburite in one field of view is considered unqualified. 4.2.5 The image field of view size is 75mm×56mm5 Metallographic structure rating
5.1 Rating of graphite
Graphite is evaluated according to the first level diagram under magnification of 100 times. The description of each level is shown in Table 1 .Level picture (100×)
Picture level 11
Picture 3
2
Level 3
Picture level 22
Picture Level 44
Level
2
4
6
6
Level 5
Picture 77 Level||tt ||JB/T6290--92
Table 1
Microstructure
Fine A-type graphite, evenly distributed
Type A right chlorine + type B stone scene , evenly distributed
B-type graphite, evenly distributed
A-type stone feel + D-type stone quantity, evenly distributed
E-type stone photo <10%
E-type graphite<20%
E-type graphite>20%
Thick A-type graphite
Picture level 66
Picture level 88
Picture
3
5
6
7
8
3
5.2 Rating of matrix tissue||tt| |5.2.1 Distribution rating of phosphorus eutectic
JB/T6290-92
The distribution of phosphorus eutectic is evaluated according to the second level diagram under 100 times magnification. The description of each level is shown in Table 2. Second level picture (100×)
Picture level 91
Picture level 113
Picture level 135
Picture level 102
Picture 124||tt ||Figure 146 Level
Level
1
3
6
6
5.2.2
JB/ T6290--92
Table 2
Distribution of phosphorus eutectic
The phosphorus eutectic is in the form of an intermittent network, with fine mesh and even distribution. The phosphorus eutectic is in the form of an intermittent network, and the network is The pores are larger and the distribution is uniform. The phosphorus eutectic is in the form of a discontinuous network. A small amount of the phosphorus eutectic is in the form of a dendritic network. The phosphorus eutectic in a small amount is dendrite segregated and has a severe dendrite distribution
The crystals show severe segregation distribution
The size of the phosphorus eutectic is evaluated according to the third-level diagram at 500 times magnification. The description of each level is shown in Table 3. The third-level diagram (500×)
Figure 15|| tt||Figure 17
Level 3
Figure Level 162
Figure Level 184
No.
10
11||tt| |12
13
14
level
different
2
3
4
5.2 .3 Rating of phosphorus eutectic complex
JB/T6290—92
Figure 195 level
Table 3
Size of phosphorus eutectic
Small Bulk phosphorus eutectic
Medium chain phosphorus eutectic (chain length <200μum)) Medium block phosphorus eutectic (area <2000μm\) Long chain phosphorus eutectic (chain length>200μm)||tt ||Bulk phosphorus eutectic (area>2000μm*)
The phosphorus eutectic complex is evaluated according to the fourth level diagram under 500 times magnification. The description of each level is shown in Table 4. The fourth level picture (500×)
Picture level 201
Picture level 212
15
16
17
18|| tt||19
Level
2
JB/T6290-92
Table 4
eutectic complex structure
small pieces Like phosphorus eutectic complex (carbide area <500um*, length <50m) Bulk phosphorus eutectic complex (carbide area >500um, length >50um) 5.2.4 Rating of free iron wire
The free iron cable body is evaluated according to the fifth level diagram under 200 times magnification. The description of each level is shown in Table 5. The fifth level diagram (200×)
Fig. 221 level
Fig. 243 level||tt ||Picture level 232
Picture level 254
Picture
No.
20
21
2
Level| |tt||1
2
3
4
5.2.5 Pearlite rating
JB/T6290--92
Table 5
Ferrite content
Ferrite <1%
Ferrite Ferrite<2%
Ferrite<3%
Ferrite>3%
The pearlite matrix is ??evaluated according to the sixth level diagram under 500 times magnification, and its levels are explained. See Table 6. The sixth level picture (500×)
Picture level 261
Picture level 283
8
Picture level 272
Picture level 294
Picture number
22
23
24
25
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