JB/T 5937-1991 General technical requirements for grey iron castings for construction machinery
Some standard content:
Machinery Industry Standard of the People's Republic of China
JB/T5937-1991
Engineering Machinery
General Technical Conditions for Grey Iron Castings
Issued on December 12, 1991
Implementation by the Ministry of Machinery and Electronics Industry of the People's Republic of China on July 1, 1992
JB/T5937-1991
Subject Content and Scope of Application
Cited Standards
Technical Requirements
Test Methods
Inspection Rules
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Appendix A
Appendix B
Appendix C
Appendix D
Machining allowance of castings (supplement)
Non-casting hole size range (reference):
Casting weight tolerance supplement)
Die draft angle of castings (reference
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Machinery Industry Standard of the People's Republic of China
Engineering Machinery
General Technical Conditions for Grey Iron Castings
Subject Content and Scope of Application
JB/T 5937-1991
This standard specifies the technical requirements, test methods, inspection rules, marking, packaging, transportation, and storage of gray iron castings in engineering machinery products.
This standard applies to gray iron castings with flake graphite. 2
Referenced standards
GB5612
GB7216
GB9439
GB 977
GB223.1~223.5
GB2828
Technical requirements
Method of indicating cast iron grades
Metallography of grey cast iron
Grey cast iron parts
Test methods for mechanical properties of grey cast iron
Metal Brinell hardness test method
Surface roughness comparison specimen
Casting surface
Sample collection method for chemical analysis of steel and allowable deviation of chemical composition of finished products Chemical analysis methods for steel and alloys
Batch inspection counting sampling procedure and sampling table (applicable to inspection of continuous batches) This standard specifies the six grades of grey iron castings, namely HT100HT150, HT200, HT250, HT300 and HT350, based on the tensile strength of $30mm single cast test bars and in accordance with GB5612. 3.2 Mechanical properties
Tensile strength
When the tensile strength of gray iron castings is measured by the sample processed by single casting test, its value shall comply with the provisions of Table 1. Table 1
Minimum tensile strength approved by the Ministry of Machinery and Electronics Industry on December 12, 1991
Implementation on July 1, 1992
JB/T 5937-1991
Tensile strength of cast test bars (blocks)
When the wall thickness of the casting exceeds 20mm and the weight exceeds 200kg, and there are special requirements, after consultation and agreement between the supply and demand parties, the tensile strength can also be measured by using the sample processed by the cast test ladder or cast test block with similar cooling conditions to the casting. Its tensile strength value shall comply with the provisions of Table 2.
Casting mold
Minimum tensile strength
Attached chain test bar
Attached test block
(reference value)
Note①The strength of HT100 grade gray iron castings is too low at thick sections and has no practical value. ②When the wall thickness of the casting exceeds 300mm, its mechanical properties should be negotiated by the supply and demand parties.②The values in the brackets are only applicable when the wall thickness of the casting is greater than the diameter of the specimen. R25mm
Tensile strength of gray iron castings with different wall thicknesses
The tensile strength of gray iron castings is related to the wall thickness of the castings. Different tensile strengths will be obtained at different wall thicknesses of the same grade of gray iron castings. Table 3 lists the reference values of tensile strength that can be achieved for gray iron castings of different wall thicknesses of various grades. When the supply and demand parties agree, the test blocks cut from the castings can also be processed into test specimens to measure the tensile strength of the castings. The tensile strength value shall conform to the provisions of Table 3. 3.2.2 Hardness
If the ordering unit requires hardness as the mechanical property of the casting material, it shall conform to the provisions of Table 4. 3.3 Chemical composition
If there are special requirements, it shall be indicated in the sample or relevant technical documents.
JB/T5937-1991
Reduced wall thickness
Minimum tensile strength
Note: When the wall thickness of the casting is uniform and the shape is simple, reference data can be found in this table; when the wall thickness of the casting is uneven or there is a core, this table can only approximately give the approximate tensile strength values at different wall thicknesses.
Hardness classification
Hardness range on the casting HB
3.4 Metallographic structure
≤170
Gray iron casting hardness classification
150~200
170~220
190~240
210260
230~280
When the metallographic structure of the casting is subject to special requirements, it should be indicated in the drawings or relevant technical documents, and its metallographic structure should comply with the provisions of GB7216.
3.5 Geometry and size
The geometry and size of the casting shall comply with the requirements specified in the drawings or order agreements. 3.6 Dimension tolerance
3.6.1 The dimensional tolerance of castings specified in this standard refers to the tolerance that should be achieved under normal production conditions. 2 The numerical value of the dimensional tolerance of castings shall comply with the provisions of Table 5; the tolerance grade shall be selected according to the provisions of Table 6. 3.6.2
Basic dimensions of castings
JB/T5937-1991
Tolerance values of casting dimensions
Note: ① Basic dimensions of castings refer to the dimensions given on the drawings, which should include machining allowances and draft angles. ② For CT13 to CT15 grades with basic dimensions less than or equal to 16mm, the tolerance value of CT12 is used. Table 6
Mass production in batches
Casting process method
Hand-made sand mold
Sand mold machine mold and polishing
Metal mold
Low pressure casting
Investment casting
Tolerance grade
Dimensional tolerance grade of castings
Small batch and single piece production
Molding material
Dry and diffuse sand
Self-hardening sand
Tolerance grade
Note: For small batch and single piece production, when the basic size of the casting is less than or equal to 16mm, its tolerance grade is increased by 2 forgings; when it is greater than 16mm to 25mm, its tolerance grade is increased by 1 grade.
The tolerance grade of the casting should be indicated in the drawing or relevant technical documents. If not indicated, the lowest tolerance grade shall be used. Different tolerance grades are allowed within a certain local range of the same casting, but the tolerance value should be indicated in the drawing or relevant technical documents.
Tolerance zone position
The tolerance zone should be arranged symmetrically with respect to the basic size of the casting, that is, half of the tolerance is located on the positive side and the other half is located on the negative side (see Figure 1); when there are special requirements, the tolerance zone can also be arranged asymmetrically, but it should be indicated on the drawing. 3.6.5.2
In the parts where the design requires a slope, the slope tolerance should be arranged symmetrically along the inclination direction of the slope (see Figure 2). Internal and external corner tolerances
For the internal and external fillet tolerances of castings, the tolerance values in Table 5 are used as the upper limit, and the lower limit is zero. 4
Basic dimensions of castings
Minimum limit dimensions
Maximum limit dimensions
3.6.7 Wall thickness tolerance
JB/T5937-1991
The wall thickness tolerance is selected one level lower than the tolerance grade selected for the casting. 3.6.8 Misalignment value
Casting dimension tolerance zone
Generally, the misalignment value (see Figure 3) must be within the tolerance value in Table 5. When the misalignment value needs to be further limited, it should be indicated on the drawing and its value should be selected from Table 7.
Tolerance grade
Misalignment value
3.6.9 Drawing marking
Specially required tolerances should be marked directly after the basic dimensions of the casting. For example: 95±1.1 or 951.
3.7 Machining allowance
3.7.1 The machining allowance of castings shall comply with the provisions of Appendix A (Supplement). 3.7.2 The minimum dimensional limit deviation of the machined surface of the casting shall ensure a machining allowance of not less than 1/3. 3.7.3 The size range of non-cast holes can refer to the provisions of Appendix B (reference). 3.8 Geometric shape tolerance
3.8.1 The bending and warping deformation of castings can be corrected, but the deformation after correction shall not exceed the provisions of Table 8 on the non-machined surface. On the machined surface, a machining allowance of not less than imm shall be guaranteed. Large size of the measured surface
Bending and warping deformation
≤250
JB/T 5937—1991
>250~500
>500~800
>800~-1200
>1200~4000
The eccentricity of the casting shall ensure that there is a machining allowance of not less than 1/3 on the machined surface and not more than the specification in Table 5 on the non-machined surface. 3.9 Weight tolerance
The weight tolerance of castings shall comply with the provisions of Appendix C (supplement). If there are special requirements, they shall be indicated in the drawings or relevant technical documents. 3.10 Draft angle
The draft angle value of castings can refer to the provisions of Appendix D (reference). 3.11 Surface quality
3.11.1 If there are special requirements for the casting surface roughness of the casting, it should be indicated in the drawing or relevant technical documents; if not indicated, the general R. The maximum allowable value is 50μm.
The residual traces on the casting surface shall comply with the provisions of Table 9. 3.11.2
Burrs, molding sand, core sand, core bone, sand-sticking porcelain mouth, vents and other concave and convex defects
Not allowed
The concave and convex amount on the non-machined surface shall not exceed 1.5mm, and the allowed protrusion on the machined surface shall not exceed 5mm. The concave amount should ensure 1/3 machining allowance
The allowed protrusion after grinding shall not exceed 1.5mm
The allowed defects on the non-machined surface of the casting shall comply with the provisions of Table 10. The allowed defects on the surface of the casting after machining shall comply with the provisions of Table 11. Defects are not allowed to appear at the same time on the symmetrical positions on both sides of the same section of important parts and important parts of castings. Table 10
Blisters, pores
Sand inclusions, scars
Cold shut, wrinkles
Cracks, pores
A (liquid flow surface of high-pressure vessels and important parts and important parts such as impact-resistant, pressure-resistant and wear-resistant parts)
Defect size
Defect depth
Number of defects
Not more than 1/7
Within 50mm
Not more than
Wall thickness
Not more than 1/7
Within 4100mm
Not more than】
|Wall thickness
Defect distance
Defect depth is not more than 1/7 of the wall thickness, no more than 3 in a circle of 450mm
B(General mechanical parts)
Defect size
Defect depth
Number of defects
In $50mm
No more than 1/3
No more than 1/3
Wall thickness
In 100mm
No more than 2
No more than 1/7
Wall thickness
In 100mm
|No more than 1
Defect spacing
Defect depth is not greater than 1/3 of the wall thickness, no more than 6 in a $50mm circle
After trimming, the wall thickness should be within the dimensional tolerance range. No
Defect size
3.12 Defect repair
Defect depth
Not greater than
1/7
Not greater than
1/5
JB/T5937-1991
Defect condition
Number of defects in a 50mm
circle
(pieces)
Not allowed to exist
Defect distance
Entire, etc.
(pieces)
Hydraulic (gas) pressure parts, sealing surfaces, friction surfaces, etc. Bushing inner surface, etc.
Other matching surfaces
Flange, upper and lower joint surfaces of the box
Village bushing outer surface, keyway, etc.
Non-matching machined surfaces such as wheel rims, wheel hub end faces, etc. worktable surfaces, etc.
3.12.1 If the casting defects on the non-machined surfaces of castings or the machined Class E surfaces exceed the provisions of Tables 9 to 11, but do not exceed the provisions of Table 12. And after repair, if it does not affect the service life and performance of the castings, then repair is allowed; but for castings that are not allowed to have defects, repair is not allowed.
Non-box parts
Box parts
Important parts such as gear boxes and
Important parts
Clean them.
The percentage of total area of sand holes to the area of the surface where they are located
The ratio of the length of crack to the length along the crack direction of the surface where they are located
≤1/3
≤1/2
Wall where they are located
Not allowed to exist
Number of
Number of grains on the whole piece
(pieces)
Before welding repair, the defects must be scraped off until good metal appears. And the defects within 30mm from the edge of the groove and on the surface of the groove that are not important parts shall be cleaned. Epoxy resin repair is allowed. After welding repair, the repaired part shall be repaired to meet the surface quality requirements of the casting, and there shall be no defects such as incomplete penetration, cracks, slag inclusions, pores, etc. 3.12.4
3.12.5 After welding repair, the castings that originally required aging treatment must be aged; castings with airtightness requirements must be subjected to leakage tests; castings with hardness requirements, the difference between the hardness of the weld repair and the base material hardness should be within the range of ±20HB. 3.13 Heat treatment
If the castings need to be artificially aged or naturally aged, it should be indicated in the drawings or relevant technical documents. 3.13.1
If the casting is completely or partially too hard, and white spots appear on the edge or thin wall of the casting, heat treatment is allowed to improve the cutting performance. Test method
4.1 Preparation of test bars (blocks) and test specimens
JB/T 5937-1991
Single casting test bars and attached casting test bars (blocks) are prepared in accordance with the provisions of GB9439; tensile test specimens are processed and manufactured in accordance with the provisions of GB977. 4.2 Mechanical property tests
4.2.1 Tensile tests are carried out in accordance with the provisions of GB977, and 4.2.2 Hardness tests are carried out in accordance with the provisions of GB231. The specimens for hardness tests are taken from the ends of the specimens for tensile tests. If hardness tests are required on castings, they must be carried out after machining to remove 1 to 2 mm of the surface skin. 4.3 Chemical analysis
4.3.1 The sampling method for chemical analysis of castings shall be carried out in accordance with the provisions of GB222, and 4.3.2 The arbitration method for chemical composition of castings shall be carried out in accordance with the provisions of GB223.1~223.5. 4.4 Metallographic structure
The metallographic inspection of castings shall be carried out in accordance with the provisions of GB7216, and 4.5 Surface roughness
The inspection of the casting surface roughness of castings shall be carried out in accordance with the provisions of GB6060.1. 4.6 Geometric shape, size, surface quality
The geometric shape, size and surface quality inspection of castings shall be carried out by visual inspection or appropriate measuring tools or in accordance with the provisions of relevant test methods. 5 Inspection rules
5.1 The castings shall be inspected and accepted by the quality inspection department of the manufacturer according to the drawings, relevant technical documents and this standard. The ordering unit has the right to conduct re-inspection.
5.2 Tensile test
5.2.1 At least one tensile test shall be carried out for each batch. 5.2.2 Evaluation of test results
5.2.2.1 When testing the tensile strength, first use a tensile test specimen for testing. If it meets the requirements, the batch of specimens is qualified in terms of material. If the test results do not meet the requirements, but it is not caused by Article 5.2.3, two more specimens can be taken from the same batch for retesting. 5.2.2.2 If the retest results all meet the requirements, the batch of castings is still qualified in terms of material. If there is still one specimen that does not meet the requirements in the retest results, the batch of castings is unqualified.
5.2.2.3 Validity of the test
If the test results do not meet the requirements due to one of the following circumstances, the test is invalid. The specimen is improperly installed on the testing machine or the testing machine is improperly operated. a.
The specimen has casting defects or the specimen is improperly cut. b.
The specimen is broken outside the parallel section.
There are casting defects on the fracture surface after the specimen is pulled apart. At this time, the test should be repeated according to Articles 5.2.2.1 and 5.2.2.2. 5.3 Hardness test
5.3.1 The number of hardness tests to be conducted on each batch of castings shall be agreed upon by the supply and demand parties. 5.3.2 Evaluation of test results
5.3.2.1 During the hardness test, the hardness value is first measured at one point. If it meets the requirements, the material of the batch of castings is qualified. If the test results do not meet the requirements, the hardness values of two points near the measurement point can be measured again for re-testing. 5.3.2.2 If the re-test results meet the requirements, the material of the batch of castings is still qualified. If the hardness value of one point does not meet the requirements, the material of the batch of castings is unqualified.
5.4 Chemical analysis
The chemical composition of the castings shall be inspected batch by batch according to the melting furnace, and shall be used as the basis for acceptance when there are chemical composition requirements. 5.5 Metallographic structure
The metallographic structure of the castings shall be inspected according to the requirements of Article 3.4. 8
6 Geometry and size
JB/T5937-1991
The geometry and size of castings shall be checked in accordance with the requirements of 3.5 to 3.8. 5.7
Weight tolerance
The weight tolerance of castings shall be checked in accordance with the requirements of 3.9. Surface quality and defect repair quality
The surface quality and defect repair quality of castings shall be checked in accordance with the requirements of 3.11 and 3.12. The geometry, size, surface quality and defect repair quality of castings shall be checked piece by piece for the first batch and single piece production; for those that have been 5.9
regularly mass-produced and have stable processes, random inspections shall be carried out. The random inspection method shall be specified by the manufacturer in the product technical standards or ordering technical requirements according to the provisions of GB2828 based on the product batch size and quality level. 6 Marking, packaging, transportation and storage
6.1 Marking and certificates
6.1.1 If the size of the casting allows, the manufacturer's trademark and other necessary marks should be made on the non-machined surface. The position, size and method of marking should be agreed upon by the supplier and the buyer, but care should be taken not to damage the quality of the casting. When it is impossible to mark the casting, the mark can be printed on the label attached to each batch of castings.
Castings leaving the factory should be accompanied by an inspection certificate or quality certificate. It must include 6.1.2
Manufacturer name;
Casting name;
Casting drawing number (or order contract number), material brand and necessary inspection results; c
Manufacture date (or number) or production batch, d.
Packaging, transportation and storage
The packaging, transportation and storage of castings should comply with the provisions of relevant standards or order agreements. 912 requirements. The geometry, size, surface quality and defect repair quality of the castings shall be checked piece by piece for the first batch and single piece production; for those that have been regularly mass-produced and have stable processes, random inspections shall be carried out. The random inspection method shall be specified by the manufacturer in the product technical standards or ordering technical requirements according to the product batch size and quality level in accordance with the provisions of GB2828. 6 Marking, packaging, transportation, storage
6.1 Marking and certificate
6.1.1 If the size of the casting allows, the manufacturer's trademark and other necessary marks shall be made on the non-machined surface. The position, size and method of marking shall be agreed upon by the supply and demand parties, but care shall be taken not to damage the quality of the castings. When it is impossible to mark the casting, the mark can be printed on the label attached to each batch of castings.
The castings leaving the factory shall be accompanied by an inspection certificate or quality certificate. 6.1.2 The manufacturer's name; casting name; casting drawing number (or order contract number), material grade and necessary inspection results; c. manufacturing date (or number) or production batch; d. Packaging, transportation and storage The packaging, transportation and storage of castings shall comply with the relevant standards or order agreement.12 requirements. The geometry, size, surface quality and defect repair quality of the castings shall be checked piece by piece for the first batch and single piece production; for those that have been regularly mass-produced and have stable processes, random inspections shall be carried out. The random inspection method shall be specified by the manufacturer in the product technical standards or ordering technical requirements according to the product batch size and quality level in accordance with the provisions of GB2828. 6 Marking, packaging, transportation, storage
6.1 Marking and certificate
6.1.1 If the size of the casting allows, the manufacturer's trademark and other necessary marks shall be made on the non-machined surface. The position, size and method of marking shall be agreed upon by the supply and demand parties, but care shall be taken not to damage the quality of the castings. When it is impossible to mark the casting, the mark can be printed on the label attached to each batch of castings.
The castings leaving the factory shall be accompanied by an inspection certificate or quality certificate. 6.1.2 The manufacturer's name; casting name; casting drawing number (or order contract number), material grade and necessary inspection results; c. manufacturing date (or number) or production batch; d. Packaging, transportation and storage The packaging, transportation and storage of castings shall comply with the relevant standards or order agreement.
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