JB/T 5942-1991 General technical requirements for open-die forgings for construction machinery
Some standard content:
Machinery Industry Standard of the People's Republic of China
JB/T5942-91
Engineering Machinery
General Technical Conditions for Free Forgings
Issued on December 12, 1991
Issued by the Ministry of Machinery and Electronics Industry of the People's Republic of China
Implemented on July 1, 1992
Machinery Industry Standard of the People's Republic of China
Engineering Machinery
General Technical Conditions for Free Forgings
1 Subject Content and Scope of Application
JB/T5942-91
This standard specifies the technical requirements, test methods, inspection rules, marking, packaging, transportation and storage of forgings in engineering machinery products.
This standard is applicable to carbon steel, high-quality carbon and alloy structural steel forgings manufactured by free forging and die forging. Reference standards
JB4249
JB4250
Machining allowance and tolerance of free-plated steel parts on manganeseMachining allowance and tolerance of steel tire die forgings on hammerSampling method for chemical analysis of steel and allowable deviation of chemical composition of finished productsGB223.1~223.65
Chemical analysis methods for steel and alloys
GB2975
GB1958
GB2828
3 Technical requirements||tt| |3.1 Steel for forgings
Metal tensile test method
Metal Charpy (U-notch) impact test methodMetal Brinell hardness test method
Steel mechanical and process performance test sampling regulationsMacrostructure and defect acid etching test method for steelShape and position tolerance·Testing regulations
Batch inspection counting sampling procedures and sampling tables (applicable to continuous batch inspection)3.1.1 Forgings can be directly forged with steel ingots. The steel ingots should be killed steel, and the furnace number must be marked, and a certificate of inspection qualification must be attached. 3.1.2 Forgings can be forged with steel forged from rolled products or steel ingots. These steels must have a factory certificate of compliance. 3.1.3 Steel ingots, steel pieces and rolled products without certificates of conformity must be retested according to relevant material standards and can only be used after being confirmed as qualified. 3.2 Manufacture of forgings
3.2.1 Before forging, surface defects of steel pieces or steel ingots must be removed, and sufficient cutting must be done at both ends of the steel ingots. 3.2.2 Forging ratio of forgings
3.2.2.1 When shaft forgings are forged with steel ingots, if calculated based on the main body section, the forging ratio shall not be less than 3 if no upsetting is performed during forging, and the forging ratio shall not be less than 2.5 if upsetting is performed during forging; if calculated based on flanges or other protruding parts, the forging ratio shall not be less than 1.7. When forging with steel bars or steel sections, if calculated based on the main section, the forging ratio shall not be less than 1.5; if calculated based on flanges or other protruding parts, it shall not be less than 1.33.2.2.2 The forging ratio of ring forgings shall generally not be less than 3. 3.2.2.3 Disc forgings; when directly roughened with steel ingots, the forging ratio shall not be less than 3; in other cases, the forging ratio shall generally not be less than 3, but the last process shall not be less than 2.
3.2.2.4 When users have special requirements for the forging ratio of certain forgings, it should be determined by negotiation between the supply and demand parties. Approved by the Ministry of Machinery and Electronics Industry on December 12, 1991 and implemented on July 1, 1992
JB/T5942-91
3.2.3 During the forging process, the heating and cooling of the rough, the control of the initial forging and final forging temperature should be carried out according to the heating and heat treatment specifications, and technical records should be made for important forgings.
3.3 Chemical composition
The chemical composition of steel for forgings should comply with the provisions of the current national standards and industry standards. When users have special requirements, it should be determined by negotiation between the supply and demand parties.
3.4 Mechanical properties
3.4.1 The mechanical properties of the longitudinal test specimens of forgings should comply with the provisions of Tables 1 to 3. The mechanical properties of tangential and transverse specimens are listed in Table 4 according to the percentage of mechanical properties of longitudinal specimens. 3.4.2 Test classification of forgings
Forgings are divided into five test levels: 1, 2, 3, 4, and 5 according to their use and working conditions. The test specifications are shown in Table 5. 3.4.3 The test level of forgings shall be indicated on the drawings and order contracts. Marking example: 3—JB/T5942—91
If the test level of forgings is not indicated in the drawings or order contracts, it shall be treated as level 1. 3.5 Heat treatment of forgings
3.5.1 When heat treatment is performed on forgings after forging, the heat treatment specifications shall be formulated by the manufacturer. If the user has special requirements, they shall be agreed upon by both parties and indicated in the contract.
3.5.2 After heat treatment of forgings, if the bending and warping deformations produced exceed the tolerance range, they shall be straightened by the manufacturer. After straightening in the cold state (carbon content of forgings is less than 0.3%) and semi-hot state, forgings of grades 4 and 5 shall be tempered to eliminate stress and ensure their mechanical properties. Whether to temper forgings of grades 1, 2 and 3 shall be agreed upon by the supplier and the buyer. 3.6 Surface quality
3.6.1 If there are defects such as interlayer, folding, forging scratches, cracks, scars and slag inclusions on the forgings, they shall comply with the following provisions. 3.6.1.1 Defects on the machined surface of forgings shall be subject to the consent of the user, and their maximum depth is allowed to be kept below 1/2 of the machining allowance. 3.6.1 .2 For defects on the non-machined surface of forgings, the maximum depth of repair shall not exceed the lower deviation of the size at that location. The repaired area must be smooth.
3.6.1.3 When the depth of surface defects of forgings exceeds the machining allowance, the defects can be removed and welded with the consent of the purchaser. The quality of the welded repair should meet the requirements of the purchaser.
3.6.2 No white spots are allowed on forgings. Forgings with white spots should be scrapped, and forgings with the same smelting furnace number and heat treatment in the same furnace as the forging should be inspected one by one.
3.7 Geometry Shape, size, machining allowance and tolerance 3.7.1 The geometric shape and size of forgings shall comply with the requirements of forging drawings. 3.7.2 The machining allowance and tolerance of forgings shall comply with the provisions of JB4249 and JB4250. 3.8 Shape and position tolerance
3.8.1 The straightness of forgings
For machined surfaces, it shall not exceed 1/5 of the actual machining allowance of its cross section; for non-machined surfaces, it shall comply with the provisions of Table 6. 3.8.2 Flatness of forgings
For machined surfaces, the flatness shall not exceed the machining allowance of the plane. 1/3 of the actual machining allowance; the tolerance of the corresponding size shall not exceed that of the non-machined surface. 3.8.3 The roundness and cylindricity of the forging shall be within the corresponding size tolerance range. 3.8.4 The parallelism, verticality, coaxiality and symmetry of the forging shall not be less than 1/2 of the actual machining allowance for the machined surface, and shall not be greater than 1/2 of the corresponding size tolerance of the surface for the non-machined surface. 3.9 Residue on the parting surface
After the flash on the machined surface is removed, its residual disk shall comply with the provisions of Table 7; the flash on the non-machined surface must be removed cleanly.
3.10 The displacement of die forgings shall comply with the provisions of Table 8. 2
Extension strength. ,
JB/T5942-91
Mechanical properties of carbon cable structural steel
Material thickness (diameter)
Tensile strength
315~390
335410
375~460
410510
490~610
Elongation. ,
Steel thickness (diameter)
Impact test
Impact energy
(longitudinal)
not less than
35SiMn
42SiMn
15CrMo
20CrMo
35CrMo
42CrMo
35CrMnSiA
20CrMnMo
40CrMnMo
20CrMnTi
30CrMnTi
Specimen rough
JB/T5942-91
First tempering
Second tempering
780~820
880Temperature tempering at 280~310
Table 2
Coolant
Water, oil
Water, oilwwW.bzxz.Net
Note: ①The heat treatment listed in the table allows adjustment range: tempering less than 15℃, low temperature tempering less than 30℃, high temperature tempering less than 50℃, ②Normalizing can be performed on steel before tempering, and normalizing can be used instead of first tempering for titanium steel.
?No yield was found on the steel during the tensile test, so the yield strength could not be determined. , under such circumstances, it is allowed to determine the nominal super service strength e1: junction
coolant
water, oil
water, oil
water, oil
water, oil
water, oil
water, oil
water, oil
water, oil
water, oil
water, oil
water, oil
water, oil
water, oil
air, oil
water, air
water, oil
water, air
water, oil
water, air
tensile strength.
Yield strength
JB/T5942—91
Elongation%,
Reduction of area
Impact energy
Steel delivery status
Hardness HB
Not more than
Heat treatment
JB/T594291
Mechanical properties of high-quality carbon structural steel
Tensile strength
Yield strength
Elongation
Reduction of area
Not less than
Impact energy
Steel delivery status
Not more than
Unheat treated
Annealing pot
Note: ①For steel with a diameter or thickness less than 25mm, heat treatment is carried out on a rough specimen with the same cross-sectional size as the finished product. ② The recommended holding time for normalizing listed in the table is not less than 30min, air cooling, recommended holding time for quenching is not less than 30min, water; recommended holding time for tempering is not less than Th.
Percentage reduction of mechanical properties of tangential and transverse specimens Acid flat steel and electric furnace steel
Mechanical properties
Tensile strength
Fuzz strength
Specimen orientation
Forging ratio
125t steel
Basic open hearth steel
>25t steel
Mechanical properties
Elongation
Reduction of area
Type of impact toughness
Specimen orientation
Required to be measured
Mechanical properties
Not tested
HB,a,or
HB,,or.
Acid open-hearth and electric furnace steel
Forging ratio
JB/T594291
Continued Table 4
1~25t steel rotation
Table 5 Test classification of forgings
Number of test items
The number of spot checks shall be stipulated in the contract between the supply and demand parties
Piece-by-piece test
Piece-by-piece test
Piece-by-piece test
Basic open-hearth steel
Axis check number The quantity is stipulated in the contract between the supply and demand parties. Piece-by-piece test. Piece-by-piece test. >25t ingots. Conditions for constituting a batch. One pot number. Same heat treatment. Same furnace steel. Same furnace heat treatment. Note: Each batch of forgings should be forged according to one drawing. If permitted by the contract, forgings with similar shapes and sizes forged according to different drawings can also be included in one batch. Table 6. Straightness of forgings
Diameter or side length
Length of forgings
>160~250
>250~400
>400~630
>630~1000
>1000~1600
>1600~2500
>2500~4000
80~120
120~160
Straightness of forgings (not more than)
160~200
Schematic diagram||tt ||Length or maximum width of forging
>50~120
>120~250
>250~500
Test method
JB/T5942—91
Residual amount of forging
Maximum dimension A of parting surface
≤100
>100~200
Misalignment of forging
Maximum height of forging
Allowable misalignment
Chemical analysis of forgings shall be carried out in accordance with the provisions of GB222 and GB223.1~223.65. 4.1
4.2 Mechanical property tests shall be carried out in accordance with the following standards: a.
Tensile test shall be carried out in accordance with GB228;
Impact test shall be carried out in accordance with GB229;
Hardness test shall be carried out in accordance with GB231.
Sampling direction
Residue
The cutting direction of the specimen shall be in accordance with the requirements of the drawing. If the requirements are not specified in the drawing, the manufacturer may choose the direction (longitudinal, transverse or tangential) at his own discretion. 4.2.2
Sampling location
Circular shaft: 1/3 radius from the surface;
Rectangular shaft: 1/6 diagonal from the surface; Hollow forging: 1/2 wall thickness from the surface, 1/3 wall thickness when the wall thickness exceeds 100mm; Ring and disc: The outer circle of the end face;
Special shape forgings: If the cutting location is not specified in the drawing, it shall be determined by the manufacturer. 4.2.3 The cutting method of the specimen shall comply with the provisions of GB2975. 4.2.4 Sampling quantity
It can be cut from each test block, with no less than 1 tensile specimen and no less than 2 impact specimens. 4.2.5 The cut specimens are not allowed to undergo any heat treatment. 4.3 According to the test level of the forging, the test items of the forging or the test items specified in the contract shall be tested. 4.4 If there are cracks, non-metallic debris or other defects on the surface of the forging tensile test specimen, the forging should be supplemented with low-power inspection and ultrasonic flaw detection. Low-power inspection shall be carried out in accordance with the provisions of GB226 and JB/T5942-91
4.5 White spot inspection can be carried out on the specially cut test piece or the forging body by any method that can ensure reliable inspection; if necessary, fracture inspection shall be carried out.
4.6 Shape and position tolerances shall be tested in accordance with the provisions of GB1958. 5 Inspection rules
5.1 The finished forgings shall be inspected and accepted by the quality inspection department of the manufacturing unit according to the drawings, relevant technical documents and this standard, and the ordering unit has the right to conduct re-inspection.
5.2 Chemical composition inspection
The chemical composition of the forging shall be inspected for each smelting furnace. When there is a chemical composition requirement; it shall be used as the basis for acceptance. 5.3 Mechanical property inspection
5.3.1 When a tensile test is required, at least one tensile test shall be carried out for each batch, and the test results shall comply with the provisions of Table 1, Table 2 or Table 3.
5.3.2 When an impact test is required, at least two specimens shall be taken from each batch for testing, and the average test value shall comply with the provisions of Table 1, Table 2 or Table 3.
5.3.3 If the test result does not meet the requirements due to one of the following reasons, the test result is invalid and needs to be retested. The original number of specimens should be used directly.
Irrational installation of the specimen or incorrect test operation; a.
The specimen has obvious forging defects on the outside or inside; the specimen is broken outside the gauge length.
5.3.4 Each batch of forgings shall be subjected to hardness test. During the hardness test, the hardness value shall be measured at the specified location, and the test result shall comply with the provisions of Table 2 or Table 3.
5.4 Retest regulations
When one or more performance indicators of the mechanical property test results do not meet the specified values and are not the reasons listed in Article 5.3.3, the manufacturer may retest.
5.4.1 Take out double the number of specimens from the same batch and repeat the test. If one of them is still lower than the specified value, the batch of forgings is unqualified.
5.4.2 Reheat treatment
When it is confirmed that the unqualified test results are caused by improper heat treatment, the forging and the sample can be reheat treated together and then sampled for testing. The number of repeated heat treatments shall not exceed two times, and the number of retested samples shall be the same as the first time. 5.4.3 Surface quality
The surface quality of the parts shall be inspected piece by piece in accordance with the provisions of Article 3.6. 5.5 Geometric shape, size, machining allowance and tolerance shall be inspected in accordance with the provisions of Articles 3.7.1 and 3.7.2. 5.6 Shape and position tolerance
The shape and position tolerance of forgings shall be inspected in accordance with the provisions of Article 3.8. 5.7 Residue on the parting surface
The residue on the parting surface of forgings shall be inspected in accordance with the provisions of Article 3.9. 5.8 Misalignment of die forgings
The misalignment of die forgings shall be inspected in accordance with the provisions of Article 3.10. 5.9 The first batch and single piece forgings shall be inspected piece by piece according to the provisions of 5.5 to 5.8. Forgings produced in regular batches and with stable processes shall be inspected by sampling. The sampling 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 and storage
6.1 Marking and certificate
JB/T5942—91
6.1.1 All forgings that pass the inspection shall be marked. The content of the mark is generally the drawing number (or code), steel grade, furnace number, work order number (contract number), manufacturer's mark, etc.
6.1.1.1 Large and medium-sized forgings shall be marked on prominent parts (process-specified parts). 6.1.1.2 Small batches of forgings may be labeled in batches. The labels are made of thin aluminum or steel plates and are written by punching or using indelible paint.
6.1.1.3 For forgings packed in boxes, the content of the label may be marked on the box or printed on a label that can be firmly attached to the box. 6.1.2 The delivered forgings shall be accompanied by a certificate of forging inspection, which includes: a.
Manufacturer name;
Drawing number, part name, work order number (contract number); steel grade, furnace number;
Chemical composition, various test results;
Heat treatment state of delivery;
Quantity and unit weight of forgings;
Seal of the quality inspection department and signature and date of the inspection personnel. 6.2 Packaging, transportation and storage
Forgings shall be protected after passing the inspection, and the packaging, transportation and storage shall comply with the relevant standards or order agreements. Additional remarks:
This standard was proposed and managed by Tianjin Engineering Machinery Research Institute of the Ministry of Machinery and Electronics Industry. This standard was drafted by Tianjin Engineering Machinery Research Institute of the Ministry of Machinery and Electronics Industry. The main drafters of this standard are Yang Chengshan,
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