JB/T 6289-1992 Metallographic inspection of cast aluminum pistons for internal combustion engines JB/T6289-1992 Standard download and decompression password: www.bzxz.net

J92 | | tt | | JB | ||Metallographic inspection
Implemented on 1993-07-01
Released by the Ministry of Mechanical and Electronics Industry of the People's Republic of China
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Technical requirements:
Inspection methods·
Metalographic structure grading standards...
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Machinery Industry Standard of the People's Republic of China
Internal Combustion Engine Casting Aluminum pistons
Metallographic examination
Subject content and scope of application
JB/T6289--92
This standard specifies the casting of eutectic aluminum-silicon alloys and aluminum for internal combustion engines Grades of macrostructure and microstructure of silicon-copper-magnesium alloy pistons. This standard is applicable to cast eutectic aluminum-silicon alloy and aluminum-silicon-copper-magnesium alloy pistons after heat treatment for reciprocating internal combustion engines with a diameter of less than 200 mm. Inspection of phase structure. 2. Technical requirements
2.1 Macrostructure
Macrostructure defects only refer to pinholes and looseness in the cast aluminum alloy piston, collectively referred to as hole run. 2.1.1 Dispersed pores
are evaluated according to the first level chart, with grades 1 to 4 being qualified, and those with levels greater than 4 being unqualified. ( Sodium salt deterioration): It should be a eutectic structure of fine α-solid solution and silicon. The eutectic silicon should be in the shape of small dots and fine strips. There should be no obviously bad strip silicon, large pieces of primary crystal silicon or coarse silicon. α-solid solution exists, and over-burning and cracks are not allowed to occur. Evaluate according to the third level chart, grades 1 to 4 are qualified, and those above grade 4 are unqualified. 2.2.2 Common aluminum-silicon alloy (phosphorus metamorphism): It should be a eutectic structure of fine primary crystal silicon and a solid drop. The eutectic silicon should be in the shape of short strips, and there should be no strips of silicon and large amounts of obviously poor quality. Primary crystal silicon that is massive and seriously aggregated is not allowed to have cracks or over-burned structures. It is evaluated according to the fourth level chart, with grades 1 to 4 being qualified, and those with levels greater than 4 being unqualified.
2.2.3 Aluminum-silicon-copper-magnesium alloy
should be a small a-solid solution, copper aluminum (A1, Cu) is in the shape of small pieces and strips, and silicon is in the shape of dots , small lumps or short strips, evenly distributed, and there must be no long strips of silicon, more primary crystal silicon and coarse α-solid solution. Evaluate according to the fifth level chart, levels 1 to 4 are qualified, and those greater than level 4 are not allowed. qualified.
2.2.4 Fish-like iron-phase inclusions
An appropriate amount of evenly distributed fish-bone-like iron phase inclusions are allowed, and there are not allowed to be many large or concentrated fish-bone-like iron inclusions. There are debris in the center of the phase. Evaluate according to the sixth level chart. Levels 1 to 4 are qualified, and those greater than level 4 are unqualified. 2.2.5 Acicular iron phase inclusions
A small amount of fine acicular iron phase inclusions are allowed, but there are not allowed to be many long acicular iron phase inclusions. Evaluated according to the seventh level chart, grades 1 to 4 are qualified, and those above grade 4 are unqualified. 3 Inspection method
3.1 Macrostructure inspection method
3.1.1 Sampling part
should be the entire section from the piston head to the skirt along the center line of the piston and the center line of the pin hole Section (see diagram). The Ministry of Mechanical and Electronic Industry approved the implementation on 1993-07-01 on 1992-06-10
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3.1.2 Corrosion-free method
JB/T6289--92
Trial After leveling, the sample was processed until the surface roughness parameter R. value was 1.6um, and then etched in 10% hydrogen complex aqueous solution. The eutectic saw-silicon alloy did not etch for 90 seconds; the aluminum-silicon-copper-magnesium alloy did not etch. 60s, the temperature of the etching solution is 65±2℃, and finally rinse and blow dry. 3.1.3 Rating method
Use the naked eye to evaluate the pore moisture level at the most serious pore moisture point on the entire section. 3.2 Microscopic group-level inspection method
3.2.1 Sampling location
Take a longitudinal sample at the center of the piston top (see diagram) Schematic diagram of the sampling location
A--Microscopic sampling B—Macroscopic sampling point
3.2.2 Etching method
The microstructure of eutectic aluminum-silicon alloy and aluminum-silicon-copper-magnesium alloy is displayed with 0.5% hydrofluoric acid aqueous solution or Mixed scattered etching, the etching time is 5~15B. The mixing ratio is as follows:
Hydrofluoric acid (HF)
Hydrochloric acid (HC1)
Nitric acid (HNO.)||tt ||Water (H,O)
0.5mL
1.5mL
2.5mL
95.5mL
Use 65±2 to display iron phase inclusions 20% sulfuric acid aqueous solution at ℃ will not corrode 20~308.3.2.3 Rating method
Divide the sample into 5 areas evenly from the top to the center (half of the thickness of the neck), and find in each city The worst field of view is used to evaluate the grade of the area, and the arithmetic mean of the five regional grades is used as the grade of the sample, but only a maximum of 2 of the 5 regions are allowed to exceed the qualified level.
Note: If there are decimals when averaging across 5 areas, the level will be moved back. If the average result is 5.1, it will be set as 6. 4 Metallographic structure grading standard
4.1 Macrostructure grading standard
4.1.1 Dispersed pore grading standard: Its level description is shown in Table 1.2
Level
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JB/T628992
Table 1
Kong Run Distribution
Number of pores per square centimeter
pcs/cm
<2
<5
≤15
≤25
40
>40
First level picture
Picture level 11
Picture level 22
Maximum hole diameter||tt ||mm
<0.15
≤0.30
<0.50
<0.80
≤1.20
>1.20
Drawing number
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JB/T6289-92|| tt||Picture level 33
Picture level 44
Picture level 55
JB/T6289-92
Picture level 66
4.1.2|| tt||Concentrated hole vortex classification standard: Its level description is shown in Table 2. Table 2
Grade
Classification
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2
4| | tt | |tt||The concentration of pores is serious
The concentration of pores is serious
Concentrated distribution of hole patterns
Maximum full hole diameter<0.30mm
Maximum hole diameter<0.50 mm
Maximum hole diameter<0.80mm
Maximum hole diameter<1.20mm
Maximum hole diameter<2.00mm
Maximum full hole diameter>2.00mm| |tt||Second level picture
Picture level 71
Picture number
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JB/T628992
Figure 82
Figure 93
Figure 104
4.2 Microstructure Grading standards
JB/T628992
Picture level 116
Picture level 126
4.2.1 Eutectic aluminum-silicon alloy microstructure (sodium salt deterioration, magnification 100 times) grading standards: See Table 3 for its grade description. Table 3
Farewell
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Microscopy
Group
Post
A solid falling body and eutectic silicon are tiny and evenly distributed. The melt is tiny in a circle. The eutectic silicon is star-shaped and evenly distributed. || tt | Strip-shaped, some are dot-shaped, with a small amount of small pieces (side length <0.50mm) of primary crystalline silicon. The eutectic silicon is all in the shape of long strips and has not deteriorated. The solid body is thick, eutectic silicon and tempered aluminum (AI). ,Cu) are integrated into massive blocks and distributed in chains along the grain boundaries, with overburning signs
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