This standard specifies the metallographic structure of the camshaft and injector body of the main parts of the diesel engine fuel injection pump and injector assembly. This standard is applicable to the metallographic inspection of the carburizing quenching and tempering of the camshaft made of 20, 20Cr and other steels, and the metallographic inspection of the high-frequency (or flame) quenching and tempering of the injector body made of 55, 60, ZG55, ZG60 and other steels. JB/T 5175-1991 Metallographic inspection of the main parts of diesel engine fuel injection pump and injector assembly JB/T5175-1991 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of ChinaWww.bzxZ.net
JB/T 5175-1991
Diesel engine fuel injection pump and fuel injector assembly
Metallographic inspection of main parts
Published on May 18, 1991
Implementation by the Ministry of Machinery and Electronics Industry of the People's Republic of China on January 1, 1992
Metallographic inspection of main parts of the People's Republic of China's Mechanical Industry Standard
Diesel engine fuel injection pump and fuel injector assembly
Metallographic inspection of main parts
1 Subject content and scope of application
JB/T5175-1991
This standard specifies the metallographic structure of the finished products of camshafts and injector bodies, the main parts of diesel engine fuel injection pump and injector assemblies. This standard is applicable to the carburizing quenching and tempering metallographic inspection of camshafts made of 20, 20 steel, and the high-frequency (or flame) quenching and tempering metallographic inspection of injector bodies made of 55, 60, etc. ：Referenced standards
94 008
Technical conditions for alloy structural steel
Technical conditions for high-quality carbon structural steel
Classification and technical conditions for carbon steel castings
Determination and verification of effective hardened layer depth of steel parts by carburizing and quenching Technical conditions for diesel engine injection pump camshaft
Determination of effective hardened layer depth after induction quenching or flame quenching of steel 3 Camshaft metallographic inspection
3.1 Technical requirements
3.1.1 The raw materials shall meet the requirements of
3077,
699. The camshaft forging shall be pre-heat treated. 3.1.2 The effective hardened layer depth and hardness of each part of the cam shall meet the requirements of the product drawing. 3.1.3 The carbon content of the cam carburized layer surface shall not be lower than the eutectoid composition. 55,
60 and other steel
3.1.4 The microstructure of the cam working surface should be martensite + carbide + a small amount of retained austenite. Carbide is evaluated according to the I-level diagram of this standard, and 26 is qualified. Martensite and retained austenite are evaluated according to the II-level diagram of this standard, and 25 is qualified. 3.1.5 The working surface of the finished parts is not allowed to have cracks and other abnormal structures. 3.2 Inspection method
3.2.1 The sampling part should be cut on the cross section of the cam working part, and the section is used as the metallographic grinding surface. 3.2.2
The etchant is 2%4% nitric acid ethanol solution.
3.2.3 Evaluation method
3.2.3.1 The effective hardened layer depth is measured according to 9450 (see Figure Ⅲ1). The inspection between heat treatment processes can also be approximately measured by metallographic method under 100 times magnification. Its depth is approximately hypereutectoid layer + eutectoid layer + 1/2 transition layer (see Figure IIII2). In case of any dispute, the effective hardened layer method shall be used for arbitration.
3.2.3.2 Carbides shall be evaluated by selecting the worst viewing field under 500 times magnification in the quenching and tempering state and comparing with the Class I diagram. 3.2.3.3 Martensite and retained austenite shall be evaluated by selecting the worst viewing field under 500 times magnification and comparing with the Class II diagram. 3.3 Microstructure classification standard
Approved by the Ministry of Machinery and Electronics Industry on May 18, 1991 and implemented on January 1, 1992
JB/T5175-1991
The carbide classification standard is divided into 8 grades according to the shape, size, quantity and distribution of carbides (see Figures 1 to 8). The grade description is shown in Table 1.
Needle-shaped tempered martensite
Carbides are not obvious or the number is small and they are fine-grained and evenly distributed. Carbides are fine-grained and evenly distributed.
Carbides are fine-grained and distributed in a discontinuous network. Carbides are granular and distributed in a discontinuous network.
Carbides are distributed in a small number of blocks.
Carbides are strip-shaped and distributed in a discontinuous network.
Carbides are large blocks. + Needle-shaped dense distribution
Martensite and austenite classification standard, according to the length of martensite and the amount of retained austenite is divided into 6 levels (see Figure I1Ⅱ6), and its
level description is shown in Table 2.
Fine needle-shaped martensite + troostite
Fine needle-shaped martensite + a small amount of retained austenite
Fine needle-shaped martensite + a small amount of retained austenite Needle-shaped martensite + a medium amount of retained austenite
Coarse needle-shaped martensite + a large amount of retained austenite Coarse needle-shaped martensite + a large amount of retained austenite
Carbide level diagram (magnified 500 times)
Figure 111 level
Figure 122 level
Figure 133 level
Figure 155 level
JB/T 51751991
Figure I44 level
Figure 166 level
Figure 177 level
JB/T 51751991
Figure 188 level
Martensite retained austenite level diagram (magnified 500 times) Figure II11 level
Figure I22 level
Figure II33 level
Figure I55 level
JB/T 51751991
Figure II44 level
Figure II66 level
JB/T5175-1991
Metallographic inspection of injector body
4.1 Technical requirements
Appear.
Bad material of injector body should be pre-heat treated. JB/T 5175-1991
The effective hardened layer depth and hardness shall meet the requirements of the product drawing. The seal end face of the injector body,
The microstructure shall be evaluated in accordance with the IV level diagram of this standard, and 38 levels are qualified. After the parts are quenched, the finished product is not allowed to have cracks and local melting phenomena, and the seal end face is not allowed to have abnormal structures such as leanness and decarburization. 4.2
Inspection method
The sampling position shall be longitudinally sectioned along the center of the quenched part of the injector body surface (the metallographic grinding surface shall be two sides away from the positioning hole and the return oil hole).
The etchant is 2%4% nitric acid ethanol solution.
Evaluation method
The martensite level shall be evaluated in accordance with the IV level diagram of this standard under a magnification of 500 times. The evaluation of the effective hardened layer depth shall be carried out according to
5617.
and above), and the microstructure classification should be divided into 10 levels according to the coarseness and arrangement of martensite (see Figure IV1IV10), and the level description is shown in Table 3. Table 3
Coarse martensite
Relatively coarse martensite
Medium martensite
Medium martensite
Relatively fine martensite
Fine martensite
Fine martensite
Inhomogeneous martensite
Martensite + troostite
Martensite + troostite + ferrite
Figure IV11 level
Figure IV33 level
JB/T 51751991
Martensite grade diagram (magnified 500 times)
Figure IV22 level
Figure IV44 level
Figure IV55 level
Figure IV77 level
JB/T 5175—1991
Figure IV66 level
Figure IV88 level
Additional notes:
Figure IV99 level
JB/T5175-1991
This standard is proposed and managed by Wuxi Oil Pump and Nozzle Research Institute. This standard is drafted by Wuxi Oil Pump and Nozzle Research Institute. The main drafter of this standard is Deng Dongchang.
Figure IV1010 level
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