JB/T 5939-1991 General technical requirements for steel castings for construction machinery
Some standard content:
Machinery Industry Standard of the People's Republic of China
JB/T5939—91www.bzxz.net
Engineering Machinery
General Technical Conditions for Steel Castings
Published on December 12, 1991
Published by the Ministry of Machinery and Electronics Industry of the People's Republic of China
Implemented on July 1, 1992
Subject Content and Scope of Application
Cited Standards
Technical Requirements
Test Methods
Inspection Rules
Marking, Packaging, Transportation and Storage.
Appendix A||t t||Appendix B
Appendix C
Supplementary parts for machining allowance of castings….
Weight tolerance of castings (supplementary parts)
Draft angle of castings (reference parts).
Mechanical Industry Standards of the People's Republic of China
Engineering Machinery
General Technical Conditions for Steel Castings
Main Content and Scope of Application
JB/T5939—91
This standard specifies the technical requirements, test methods, inspection rules and marking, packaging, transportation, storage, etc. of steel castings in engineering machinery products. This standard applies to carbon steel and low alloy steel castings. 2 Reference standards
Sampling method for chemical analysis of steel and allowable deviation of chemical composition of finished products Chemical analysis methods for steel and alloys
GB223.1~223.7
GB2106
GB2828
3 Technical requirements
Metal tensile test method
Metal Charpy (V-notch) impact test methodMetal Charpy (U-notch) impact test methodMetal Brinell hardness test method
Surface roughness comparison specimenCasting surface
Batch inspectionCount sampling procedure and sampling table (applicable to inspection of continuous batches) 3.1 Grade, chemical composition and mechanical properties of carbon steel castings (hereinafter referred to as castings) 3.1.1 Grade and chemical composition
The grade and chemical composition of castings shall comply with the requirements of Table 1. 3.1.2 Mechanical properties
The mechanical properties of castings shall comply with the provisions of Table 2. If the purchaser has no requirements for the cross-sectional shrinkage and impact toughness, the supplier shall select one of them. Chemical composition
ZG230-450
ZG270-500
ZG310-570
ZG340-640
Note: ① For every 0.01% reduction in carbon in the upper limit, an increase of 0.04% manganese is allowed, up to 1.20%, ② The total amount of residual elements shall not exceed 1.00%. If the purchaser has no requirements, the residual elements may not be analyzed. When using an acid furnace to produce castings, the S and P contents shall be agreed upon by the supply and demand parties. Approved by the Ministry of Machinery and Electronics Industry on December 12, 1991 Cu
Implementation on July 1, 1992
ZG230-450
ZG270-500
ZG310-570
ZG340-640
Heat treatment method
Normalizing, tempering
Cancer strength
JB/T5939--91
Table 2 Mechanical properties
Tensile strength
Elongation
Choose according to contract
Shrinkage rate
Impact properties
Note: ① The properties of each grade listed in Table 2 are applicable to castings with a thickness of less than 100mm. When the thickness of the casting exceeds 100mm, the 6a. strength specified in Table 2 is for design purposes only.
②Asv-impact absorption energy (V type); a-impact toughness (U type) 3.2 Grade, chemical composition and mechanical properties of low alloy steel castings (hereinafter referred to as castings) 3.2.1 Grade and chemical composition
The grade and chemical composition of castings shall comply with the provisions of Table 3. 3.2.2 Mechanical properties
The mechanical properties of castings shall comply with the provisions of Table 4. The mechanical properties of castings shall be based on the test results of single casting test bars. Table 3 Chemical composition
ZG35Mn
ZG45Mn
ZG50Mn
ZG42SiMn
ZG45SiMn
ZG40Cr
ZB35Mn
ZG45Mn
ZG50Mn
ZG42 SiMn
ZG45SiMn
ZG40Cr||t t||0.30~0.40
0.40~0.50
0.45~0.55
0.38~0.45
0.42~0.49
1.20~1.60
1.20~1.50||tt ||1.20~1.50
1.10~1.40
0.80~1.10
0.17~0.37
0.35~0.45
0.20~0.45
0.60~0.80
0.80~1.10
0.20~0.40
Tensile strength
Heat treatment
Normalizing, tempering
Yield strength
Mechanical properties
Elongation
0.80 ~1.10
Shrinkage
Impact toughness
175~195
195235
180~220
≥229
207~241
≤212
3.3 Casting geometry and dimensions
JB/T593991
The casting geometry and dimensions shall comply with the requirements specified in the drawing or order agreement. 3.4 Casting dimensional tolerance
The casting dimensional tolerance value shall comply with the provisions of Table 5, and its tolerance grade shall comply with the provisions of Table 6. 3.4.1
Basic casting dimensions
Casting dimensional tolerance value
Note: ① The basic casting dimensions refer to the dimensions given on the drawing, which shall include the machining allowance and draft angle. CT
② For castings with basic dimensions less than or equal to 16mm, the tolerance value of CT12 is used for grades CT13 to CT15. 3.4.2
2 Position of tolerance zone
Tolerance zones should be distributed symmetrically, that is, half of the tolerance is positive and the other half is negative (see Figure 1). However, when there are special requirements, asymmetric arrangement can also be used, and it should be indicated on the drawing or specified in the technical documents. When the casting has an inclined part, its dimensional tolerance should be marked symmetrically along the inclined surface (see Figure 2). ：Table 6 Casting Dimension Tolerance Grade
Production Method
Casting Condition
Tolerance Grade
Sand Mould Hand Moulding
Batch and Mass Production
Casting Process Method
Sand Mould Machine
Molding and Shell Mould
Investment Casting
Small Batch and Single Item Production
Molding Material
Dry and Wet Sand
Note: For small batch and single item castings, when the basic size is less than or equal to 16mm, the tolerance grade shall be increased by 2 grades; when it is greater than 16 to 25mm, the tolerance grade shall be increased by 1 grade.
3.4.3 Different tolerance grades may be selected in a certain local range of the same casting, but the tolerance value shall be indicated on the drawing or in the relevant technical documents.
Basic dimensions of castings
Minimum limit dimensions
Maximum limit dimensions
JB/T5939—91
Dimensional tolerance zones of castings
3.4.4 The tolerance grade of castings shall be indicated on the drawings or specified in the technical documents; otherwise, the lowest tolerance grade shall be used. 3.4.5 The dimensional tolerance of wall thickness shall be selected according to the lower grade of the tolerance grade selected for the casting. If the selected tolerance grade of the casting is CT13, the dimensional tolerance of wall thickness shall be selected according to CT14. 3.5 Machining allowance of castings
The machining allowance of castings shall comply with the provisions of Table A1 in Appendix A (supplement): Its machining allowance grade shall comply with the provisions of Table A2. 3.6 Geometric tolerance of castings
3.6.1. The bending and warping deformation of castings shall be measured according to the maximum size of the inspected surface. The most concave part of the machined surface shall be guaranteed to have a machining allowance of not less than 1/2 (not less than 1.5mm); the non-machined surface shall comply with the provisions of Table 7. Table Bending and warping deformation
Maximum size of the inspected surface
Bending and warping deformation
≤250
>250~630
>630~1250
>1250~3150
3.6.2 The eccentricity of the casting shall ensure that there is a machining allowance of not less than 1/3 (not less than 1.5mm) on the machined surface; and shall not exceed the corresponding dimensional tolerance or wall thickness dimensional tolerance on the non-machined surface. 3.6.3 The concave and convexity of the casting surface shall ensure that there is a machining allowance of not less than 1/3 (not less than 1.5mm) on the machined surface, and the convex part shall not exceed 5mm; when the concave or convex value on the non-machined surface exceeds the corresponding dimensional tolerance or wall thickness dimensional tolerance value, trimming is allowed.
3.6.4 Misalignment value (see Figure 3)
In general, the misalignment value must be within the tolerance value specified in Table 5. When the misalignment value needs to be further restricted, it should be indicated on the drawing and its value should be selected from Table 8.
Tolerance grade
Misalignment value
JB/T5939—91
Misalignment value
Tolerance of casting weight
The weight tolerance of castings shall comply with the provisions of Table B1 in Appendix B (Supplementary Parts), and its weight tolerance grade shall comply with the provisions of Table B2. Casting draft angle
The draft angle value of castings can refer to the provisions of Table C1 in Appendix C (Reference Parts), and the type and application of its draft angle can refer to the provisions of Table C2.
3.9 Surface quality of castings
If there are special requirements for the surface roughness of castings, they should be indicated in the drawings or technical documents. If not indicated, the general R value is 1003.9.1
μm.
The residual marks on the casting surface should comply with the provisions of Table 9. Table 9
Mold, core sand, core bone, sticking sand
Firing riser diameter
≤100
>100~180
>180~280
>280400
Not allowed
After grinding, the protrusion is allowed to be no more than 1.5mm
It should be ensured that there is no less than 1/3 of the machining allowance (no less than 1.5mm)
On the non-machined surface
Note: The listed diameter of the annular mouth refers to the wall thickness of the pipe mouth. 3.9.3Under the condition that the service life and performance of the casting are not affected, the defects allowed on the non-machined surface of the casting shall comply with the provisions of Table 10.
3.9.4Under the condition that the service life and performance of the casting are not affected, the defects on the surface after machining shall comply with the provisions of Table 11. 3.10 Repair of casting defects
3.10.1 If the casting defects on the non-machined surface or the machined surface of the casting exceed the provisions of Article 3.9 but do not exceed the provisions of Table 12, and the repair does not affect the service life and performance of the casting, repair is allowed. However, castings that are not allowed to have defects shall not be repaired.
Defect types
Scarring, etc.
Cold shut, wrinkling
JB/T5939—91
A (important castings and important parts of castings such as high-temperature and high-pressure containers, pipeline accessories, gear tooth surfaces, etc.)
Defect size
>3~↓6
Defect depth
Not more than 1/7
Wall thickness
Protrusion not more than
Number of defects
Not more than 3 within a 0mm
circle
Not more than 1 within a $50mm
circle
5mm , the remaining hole depth is not more than 1/7 of the wall thickness. The defect spacing is not more than 15~$30. B (general mechanical parts) The defect depth is not more than 1/3 of the wall thickness. The protrusion is not more than 1.5mm. The hole depth is not large. The wall thickness should be within the size deviation range after trimming. Note: ① There are two different important parts on the same casting, and the total number of defects is superimposed for assessment. ② Different types of defects appear on the same casting, and they are calculated separately. Table 11
Casting surface category
Defect size
<Tooth groove bottom width
Porosity,
Defect depth
Number of defects
Not allowed|||Not within 50mm
Not greater than 1/7
Wall thickness
Not greater than 1/5 tooth thickness
More than 3
Within a circle of 450mm
No more than 2
Defect spacing
Number of defects
Defect spacing
Within a circle of 450mm
No more than 5
Within a circle of 50mm
In 3
In a 50mm circle
No more than 1
In a 100mm
circleNo more than
In a 100mm
circleApplications
Hydraulic (pneumatic) parts, chains, sealing surfaces,
friction surfaces, important screw holes, etc.
General matching surfaces and bonding surfaces
Non-matching machined surfaces, such as wheel rims,
wheel end faces, box bottoms, etc.
No more than
On the same tooth surfaceNo more than
On the same tooth grooveNo more than 1/10 of the tooth diagram
More than 1
The number of defective teeth is less than 1/13
Total Number of teeth and not allowed to appear on three connected tooth surfaces or two tooth grooves. Casting category Non-box parts Box parts The total area of pores and defects accounts for the percentage of the surface area (%) The circumferential length of the hole is not greater than 1/5 of the circumference of the wheel hub, and the radial width is not greater than 1/3 of the wheel hub wall thickness Not greater than 1/3 The wall thickness is not greater than 1/15 Hub width Not greater than 1/2 Spoke plate thickness JB/T5939-91
Number of defects on the whole piece
Ratio of crack length to length along the
grain direction of the surface
≤1/3
≤1/4
Not more than 1/2
Whole thickness
Not allowed to exist and repair
Number of
grain on the whole piece
(pieces)
For 3 to 5 spokes, there shall be no more than 1 crack; for more than 6 spokes, there shall be no more than 2 adjacent cracks
Not allowed to exist and repair
3.10.2 Before welding, the defects must be scraped until good metal is exposed, and the area within 30mm from the edge of the groove and the groove surface must be cleaned.
3.10.3 For gears and sprockets that need to be heat treated by quenching and tempering, quenching, etc., defects on the wheel rim after machining are not allowed to be repaired. 3.10.4 After welding repair of important castings (parts with complex shapes and high strength requirements), the welded area should be annealed or tempered. 3.10.5 After welding repair, the surface quality requirements of the casting should be met, and there should be no defects such as incomplete penetration, cracks, clamps, pores, etc. 3.10.6 For castings with airtightness requirements, leakage tests should be carried out after welding repair. For castings with hardness requirements, the hardness difference between the welded area and the parent body should be within the range of ±20HB. The surface color of the welded area is allowed to be slightly different from that of the parent body. 4 Test methods
4.1 Chemical analysis
4.1.1 The sampling method for chemical analysis samples shall be carried out in accordance with the provisions of GB222. 4.1.2 Chemical composition analysis method shall comply with the provisions of GB223.1~223.7. 4.2 Mechanical properties test
4.2.1 Test block
4.2.1.1 Test blocks for mechanical properties shall be cast separately in the middle of pouring, and the selection of test blocks shall be determined by the supplier. 4.2:1.2 The shape, size and cutting position of the single-cast test block shall comply with the requirements of Figure 4. 4.2.2 The tensile strength test shall be carried out in accordance with the provisions of GB288. 4.2.3 The impact value test shall be carried out in accordance with the provisions of GB2106. Note: Under the test conditions where the supplier does not have a V-notch, it can be carried out in accordance with the provisions of GB229. 4.2.4 The Brinell hardness test shall be carried out in accordance with the provisions of GB231. 4.2.5 The surface roughness inspection method of castings shall be carried out in accordance with the provisions of GB6060.1. 4.3 The geometric shape, size and surface quality shall be inspected by visual inspection or appropriate measuring tools or relevant test methods. 5 Inspection rules
JB/T5939—91
Figure 4 Single cast test block type for mechanical properties
5.1 The castings shall be inspected and accepted by the supplier's quality inspection department according to the drawings, relevant technical documents and this standard. They can be put into storage only after they are qualified. The buyer has the right to conduct random inspection and re-inspection of castings.
5.2 Chemical composition inspection
The chemical composition of castings shall be analyzed once for each melting furnace or each batch. The analysis results shall comply with the provisions of Table 1 or Table 3. The chip-like specimen shall be obtained from 6mm below the casting surface.
5.3 Mechanical property inspection
5.3.1 Inspection
5.3.1.1 Mechanical property test Take one tensile specimen from each batch, and the test results shall comply with the provisions of Table 2 and Table 4. 5.3.1.2 When the buyer needs to conduct an impact test, take three impact specimens from each batch for testing, and the average value of the three impact specimens shall comply with the provisions of Table 2 or Table 4. The value of one of the specimens may be lower than the specified value, but shall not be lower than two-thirds of the specified value. 5.3.1.3 The test results that do not meet the requirements due to the following reasons are invalid and should be retested according to Article 5.3.2: a.
The specimen is improperly installed or the test function is abnormal; the tensile test is broken outside the gauge length;
The specimen is improperly processed;
The specimen has casting defects.
5.3.2 Retest
JB/T5939-91
When the mechanical property test results do not meet the requirements (not due to the reasons listed in Article 5.3.1.3), the supplier can retest. 5.3.2.1 Take two spare tensile specimens from the same batch for testing. If both test results meet the requirements of Table 2 or Table 4, the tensile properties of the batch of castings are still qualified. If one specimen still fails in the retest, the supplier can re-heat treat it according to Article 5.3.3.
5.3.2.2 Take three spare impact specimens from the same batch for testing. The test results shall comply with the provisions of Article 5.3.1.2. The results shall be added to the original results to recalculate the average value. If the new average value complies with the provisions of Table 2 and Table 4, the impact value of the batch of castings is still qualified; otherwise, the supplier may reheat treat according to Article 5.3.3: 5.3.3 Reheat Treatment
When the mechanical properties re-test results still do not comply with the provisions of Table 2 or Table 4, the castings and test blocks may be reheat treated and then retested according to Articles 5.3.1.1 and 5.3.1.2. However, the number of reheat treatments without the consent of the purchaser shall not exceed two times (except tempering). 5.4. Geometric shape and size, dimensional tolerance, machining allowance, geometric shape tolerance, surface quality The geometric shape and size, dimensional tolerance, machining allowance, geometric shape tolerance, and surface quality of castings shall be inspected in accordance with the provisions of Articles 3.3, 3.4, 3.5, 3.6, and 3.9 respectively.
The first batch and single piece production should be inspected piece by piece, and the castings with regular batch production and stable process should be inspected randomly. The inspection method shall be specified by the manufacturer in the product technical standards or ordering technical requirements according to GB2828 based on the batch size and quality level of the product. 5.5 Others
Other items (weight tolerance, Brinell hardness, chemical analysis of residual elements, etc.) shall be inspected according to the agreement between the supplier and the buyer. 6 Marking, packaging, transportation, storage
6.1 Marking and certificate
6.1.1. Each casting shall be marked with the following marks or part of them on the non-machined surface. For example: factory mark;
Test batch:
Other marks required by the buyer.
When it is impossible to make a mark on 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. The certificate should include: 6.1.2
Supplier name;
Casting name:
Casting drawing number or order contract number;
Manufacturing date (or number) or production batch. 6.2 Packaging, transportation and storage
The packaging, transportation and storage of castings shall comply with the relevant standards or order agreement. 9
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