This standard specifies the technical requirements, inspection methods and evaluation of the metallographic structure of the intake and exhaust valve seats for reciprocating piston internal combustion engines with a cylinder diameter less than or equal to 200 mm. This standard is applicable to the metallographic structure inspection of valve seat materials listed in JB/T 9769. Other materials of the same type can also be implemented as a reference. JB/T 8893-1999 Metallographic Inspection of Valve Seats for Internal Combustion Engines JB/T8893-1999 Standard Download Decompression Password: www.bzxz.net

ICS77.040;27.020
Machinery Industry Standard of the People's Republic of China
JB/T8893-1999
Internal Combustion Engine
Valve Seat
Metallographic Test for Valve Seat ofinternal Combustion Engines
1999-09-17 Issued
State Machinery Industry Bureau·Issued
2000-01-01Implementation
JB/T 8893—1999
Cited Standards
Test Methods and Inspection Rules
Evaluation of Metallographic Structure
JB/T8893—1999
This standard is proposed and managed by the National Technical Committee for Standardization of Internal Combustion Engines. The drafting units of this standard are: Shanghai Internal Combustion Engine Research Institute, Handan Internal Combustion Engine Parts Factory. The main drafters of this standard are: Li Shaoqiu, Zhao Shiqun, and Lu Jishen. 1
1 Scope
Mechanical Industry Standard of the People's Republic of China
Metallographic test for valve seat ofinternal combuston engines
JB/T 8893--1999
This standard specifies the technical requirements, inspection methods and evaluation of the metallographic structure of the intake and exhaust valve seats for reciprocating piston internal combustion engines with a cylinder diameter less than or equal to 200 mm.
This standard is applicable to the metallographic structure inspection of valve seat materials listed in JB 976. Other materials of the same type may also be implemented as a reference. 2 Referenced 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. The parties using this standard should explore the possibility of using the latest versions of the following standards, GB/T 7216—1988 Grey cast iron metallography
JB/T9769—1999
3 Requirements
Technical conditions for valve seats in internal combustion engines
3.1 QZ1, QZ2. QZ3 materials
3.1.1 Graphite morphology and distribution
Graphite should be type A, type E as specified in GB/T 7216, and type D, type F and a small amount of type E are allowed. Type. The graphite dispersion is large and evenly distributed. According to the first level of this standard, 1-4 levels are qualified. 3.1.2 Distribution and quantity of alloy carbides
Alloy carbides should be dispersed in the form of discontinuous mesh or small blocks. The block size is moderate. Severe dendrites and severe segregation are not allowed. The number of gold-containing carbides should be: 7%~20%. According to the second level, 1~3 levels are qualified. 3.1.3 The shape of alloy carbides
The shape of alloy carbides should be small strips and medium blocks. Large blocks are not allowed. Follow the third level assessment, 1-2 levels are qualified. 3.1.4 Matrix structure:
The matrix structure should be a correct optical structure. , needle-like structure, phosphorus content is less than or equal to 2%, free ferrite is less than or equal to 2%,: 3.2QZ4 material
3.2.1 Graphite morphology and distribution
Graphite should be in the form of floccules or dots, and the distribution is evenly distributed. According to the fourth level peeling diagram, 1~3 levels are qualified. 3.2.2 Distribution and number of gold-containing carbides
Alloy carbides should be fine and blocky, and serious irregular distribution and serious segregation are not allowed. The number of alloy carbides should be 20%-40%, and according to the fifth level diagram, 1~3 levels are qualified. 3.2.3 The morphology of alloy carbides
National Machinery Industry Bureau 1999-09-17 Approved 2000-01-01 Implementation
JB/T 8893—1999
The morphology of alloy carbides should be small or medium lumps, and large lumps are not allowed. According to the sixth level diagram, 1~2 levels are qualified. 3.2.4 Matrix structure
Should be tempered martensite.
3.3QZ5, Q26 high-cast cast iron materials
3.3.1 Distribution and quantity of alloy carbides
Gold-containing carbides should be distributed in a discontinuous mesh or dispersed state. Severe directional or plate-killing distribution is not allowed. The amount of alloy carbides should be 10%~40%, and according to the seventh level circle, 1~5 levels are qualified. 3.3.2 Alloy carbide morphology
The morphology of alloy carbides should be small or medium lumps, and large lumps or larger strips are not allowed. According to the eighth level chart, the evaluation is as follows: 1-3 levels are qualified.
3.3.3 Matrix structure
Should be tempered martensite. Granular halogen is not allowed. 4 Test methods and inspection rules
4.1 Sampling location
Any longitudinal section of the finished product of the internal combustion engine valve seat is the metallographic grinding surface. 4.2 Evaluation method
4.2.1 The distribution and morphology of graphite are evaluated by selecting the worst field of view on the grinding surface. If two standard fields are unqualified, it is unqualified. 4.2.2 The alloy carbide and matrix structure are evaluated by the representative field of view on the entire grinding surface. If three fields are unqualified, it is unqualified. 4.2.3 Inspection of graphite should be carried out on the unetched grinding surface: For the evaluation of alloy carbides and matrix structure, the sample is etched with 2%~5% nitric acid alcohol solution or blue ferric fluoride hydrochloric acid solution. 4.2.4 The evaluation of graphite in this standard should be observed at a magnification of 100 times: the distribution and quantity evaluation of alloy carbides, QZ1, QZ2, QZ3, QZ5 and QZ6 should be observed at a magnification of 200 times, Q24 should be observed at a magnification of 100 times: the morphology evaluation of alloy carbides should be observed at a magnification of 500 times.
4.2.5 The image size of this standard is 95mm×70mm. 5 Metallographic structure evaluation
S. 1 QZ1, QZ2, QZ3 materials
5.1.1 Graphite rating
Graphite is evaluated according to the first level image at a magnification of 100 times, see Table 1. Table: Graphite grading
Microstructure
Type A, evenly distributed
Type B, evenly distributed
Type A+Type B, evenly distributed
Type D+Type B, evenly distributed
Type A+Type C graphite
Severe E, D right graphite
JB/T8893—1999
First level figure (100×)
Figure 22nd level
JB/T8893—1999
Figure 33rd level
Figure 44th level
JB/T8893—1999
5S levelWww.bzxZ.net
5.1.2 Distribution and quantity grading of alloy carbidesJB/T 8893-1999
The distribution and quantity of alloy carbides are evaluated according to the second-level diagram under magnification of 200 times, see Table 2 Table 2 Distribution and quantity of alloy carbides Rating Grade
"Distribution of alloy carbides Prime number
Alloy magnets have small intermittent mesh distribution Alloy carbides are evenly dispersed (quantity = 7%) Alloy carbides have medium intermittent mesh distribution
Alloy carbides are evenly distributed (quantity -15%) Alloy carbides have large intermittent mesh distribution Alloy carbides are evenly dispersed (quantity -20%) Alloy carbides have large intermittent mesh distribution
Alloy carbides are crystal-encapsulated distribution [quantity>20%] Second-level diagram Distribution and quantity of alloy carbides (200×) Figure la level
JB/T8893-1999
Figure 9 Level 2a
JB/T 8893-1999
Figure 102 Level b
Figure H13 Level a
JB/T 8893-1999
Figure 123 Level b
Figure 134 Level a
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