Some standard content:
JB/T8421..96
Quality inspection of steel self-made forgings (hereinafter referred to as forgings) is an important means to control the quality of forgings. Due to the differences in service conditions, materials and heat treatment status, shapes, sizes, weights, and batch conditions of forgings, the inspection items for controlling the quality of forgings are different. This standard is a general inspection standard for carbon steel and alloy steel free forgings for special and general industrial use. The inspection items are determined according to the classification of forgings. The inspection items include chemical composition, mechanical properties, high and low magnification structures, ultrasonic flaw detection, appearance quality, etc. It also clearly stipulates the number of specimens for mechanical property tests, sampling locations and specimen directions, retests and reheat treatments, etc., thus providing a unified basis for the inspection of general forgings.
In this standard, the table of allowable deviations of chemical composition analysis values of finished forgings is equivalent to the content of ASTMA788-General Requirements for Forged Steels. The contents of the number of specimens, sampling location and specimen direction refer to the contents of J1SG0306≤ "General Rules for Inspection of Forged Steels" and ASTMA668 "General Industrial Carbon Steel and Alloy Steel Forgings". Appendix A of this standard is equivalent to Appendix A of ASMA788. This standard shall be implemented from July 1, 1997. Appendix A of this standard is the appendix of the standard.
This standard is proposed and managed by the National Technical Committee for Forging Standardization. The responsible drafting unit of this standard is China Second Heavy Machinery Group Corporation. The participating drafting units of this standard are Beijing Electromechanical Research Institute of the Ministry of Machinery Industry. The main drafters of this standard are Wang Li, Peng Yun, Hu Jiaer and Cai Fulin. 317
1 Scopebzxz.net
Machinery Industry Standard of the People's Republic of China
General Rules for Inspection of Steel Free Forgings
This standard specifies the general rules for inspection of steel free forgings (hereinafter referred to as forgings). JB/T 8421. 96
This standard applies to carbon steel and alloy steel forgings for general industrial use, and does not apply to forgings for special purposes or with special requirements. 2 Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB222-84 Sampling method for chemical analysis of steel and allowable deviation of chemical composition of finished products GB223.1~223.75—81~91 Chemical analysis methods for steel and alloys GB226—91 Acid immersion test method for macrostructure and defects of steel GB 228— 87
GB 229—-84
Metal tensile test method
Metal composite (U-notch) impact test method GB/T 230—91
Metal Rockwell hardness test method
GB 231---84
GB 1814 --79
GB1979-80
GB 2106--80
GB 2971--80
Metal Brinell hardness test method
Steel fracture test method
Structural steel macrostructure defect rating chart
Metal Charpy (V-type notch) impact test method Carbon steel and low alloy steel fracture test method GB4236
GB.4341-—84
GB6394
GB 8170--87
GB 10561
Steel sulfur print test method
Metal Shore hardness test method
Metal average grain size determination method
Numerical rounding rules
Microscopic evaluation method of non-metallic inclusions in steel GB/T12363--90
GB/T 13298 -91
GB/T 13299--91
Functional classification of forgings
Methods for testing metal microstructures
Methods for evaluating steel microstructures
GB/T15826-1995 Machining allowances and tolerances for hammer E steel free forgingsJB4009-85 Contact ultrasonic longitudinal wave direct flaw detection methodZB J04 005---87
ZB J04 006-- 87
Methods of penetrant testing
Magnetic particle testing of steel materials
ZBJ32003--88 Machining allowance and tolerance of free forgings on hydraulic presses 3 Chemical composition
3.1 Melting analysis
Approved by the Ministry of Machinery Industry of the People's Republic of China on September 3, 1996 318
Implemented on July 1, 1997
JB/T 8421--96
3.1.1 Steel mills shall take melting analysis samples when pouring each furnace of molten steel to determine the white content of the elements specified in the material standard. The analysis results shall meet the requirements of the material standard.
3.1.2 If multiple furnaces of molten steel are poured into a large ladle, the molten steel in the ladle shall be chemically analyzed, and the determined chemical composition shall meet the requirements of the material standard.
3.1.3 For steel ingots cast from multiple furnaces, the analysis value of each furnace or the weighted average value may be taken, and the result shall meet the requirements of the material standard. 3.1.4 For electroslag remelting steel ingots, if the remelting steel ingots are made of electrodes of the same furnace number, the chemical analysis of the remelting steel ingot (or forging) shall be taken as the smelting analysis; if the ingots are remelted in sequence by electrodes of different furnace numbers, the chemical analysis of each section corresponding to at least one electrode of each furnace number in the remelting steel ingot shall be carried out, and the measurement results of each section shall meet the requirements of the material standard. The smelting analysis results of the remelting steel ingot shall be expressed by the weighted average value of the chemical analysis of each section. 3.1.5 If the smelting analysis sample does not meet the requirements, the steel mill may take a substitute sample from a suitable position near the surface of the steel ingot or forging. 3.7.6 For all purchased steel ingots, steel or rolled products, the quality certificate shall contain the smelting analysis results of the steel mill. Manufacture) can be re-inspected by the factory. 3.2 Product Analysis
3.2.1 The purchaser may take samples for analysis on forgings representing each heat of molten steel or forgings cast from multiple heats. The sampling rules are as follows: a) For solid forgings and disc forgings, the samples shall be taken from any point within the range of one-third of the radius (or one-sixth of the diagonal) from the end face of the original lengthened section to the outer surface;
b) For hollow forgings, the samples shall be taken from the point where the wall thickness is one-half of the end face of the original lengthened section; c) For all forgings, the finished product analysis samples may also be taken from the samples for mechanical properties tests. 3.2.2 The chemical composition of the finished product analysis shall meet the requirements of the forging material standards, but the deviation specified in Table 1 is allowed. The allowable deviation of the chemical composition of the finished product analysis in Table 1 exceeds the upper limit or is lower than the lower limit. Xing element
Composition range
0.06~0.10
0.11~~0.25
0.26~0.55
0.0310.060
1.01~2.00
2.01~~5.30
5.31 ~10.00
0.91~2.10
2.11~-10.00
10.01~15.00
15, 01~~20. 00
>650～1 300
>1 300~～2 600
>5 200~10 300
≥2 600～5 200
Ingredient range
0.21～0.40
0. 41~1. 15
1.16~5.50
0. 11 ~~ 0. 25
0.26~0.50
0. 51~~1, 25
0.15~~0.50
0.26~5.00
5.01~10. 00
1. 01~4. 00
1.01~-2. 00
2.01~5.00
0.06~0.15
0.16~0.50
0.50~2.00
1 >0. 02 - 0. 19
>0. 19~0.25
0. 25~0. 35
>0.35~0.45
JB/T 8421
Table 1 (end)
The allowable deviation exceeds the upper limit or is lower than the lower limit. The cross-section should be perpendicular to the center line of the steel ingot or steel blank1
≥1300～2600
≥2 600-~5 200
≥5 200~-10 300 10 300
0、03
2 The cross-sectional area of the finished product is specified as follows: the maximum cross-sectional area of the forging after rough machining (excluding hole machining); the maximum cross-sectional area of the forging without mechanical machining; the maximum cross-sectional area of the steel blank.
3.3 Test method
3.3.1 The test method for chemical analysis shall be in accordance with the provisions of GB222. 3.3.2 Chemical analysis methods shall comply with the provisions of GB223. 4 Mechanical properties
4.1 Test items
4.1.1 The purchaser may determine the inspection level of forgings according to the provisions of GB/T12363. The inspection level of forgings is divided into five levels: 1, 』, , V, √. Each level specifies the test items and the number of forgings to be inspected, see Table 2. 321
Forging level
Chemical composition
Each--heat number
Each heat number
Each--heat number
Each--heat number
Each--heat number
Each·heat number
.JB/T 8421 - 96
Table 2 Test items and inspection quantity for forging grade Item
5% of each batch, but
not less than 5 pieces
Tensile (ob+0, or 0.2.0,)
2% of each batch, but not less than 2 pieces
Impact Ak
2% of each batch, but
not less than 2 pieces
Batch conditions
Piece-by-piece inspection
Same furnace number, same heat treatment furnace
Same steel number, same heat treatment furnace
Same steel number·same heat treatment furnace
Steel number
Each batch of forgings should be forged from the same drawing, or it can be batched from forgings of different drawings but with similar shapes and sizes. 2 After calculating the inspection quantity by percentage, the remainder less than one piece should be counted as one piece. [, The hardness value of Grade II forgings shall not be used as the basis for acceptance 4.1.2 The purchaser shall specify the grade of forgings in the contract or drawings. If there is no stipulation, the manufacturer shall deliver the forgings as Grade V. 4.1.3 1. For the impact test of Grade I forgings, the purchaser shall specify in the contract or drawings whether the notch of the impact specimen is V-shaped or U-shaped. If no stipulation is made, the manufacturer shall conduct the impact test as a U-shaped notch specimen. 4.1.4 The mechanical property test results of forgings shall meet the requirements specified in the corresponding material standards. 4.2 Number of specimens
4.2.1 When the weight of the forging to be inspected after rough machining is less than 3000kg, one set of specimens shall be taken for each piece, namely one tensile specimen and two impact specimens. 4.2.2 When the weight of the forging to be inspected after rough machining is equal to or greater than 3000kg, two sets of specimens shall be taken for each piece. The specific provisions are as follows and see Figure 1. a) For ring and disc forgings, one set of specimens shall be taken at each end 180° apart. b) For shaft and cylinder forgings, when the length is equal to or less than 2000mm (excluding the extended section of the sample material), one set of specimens shall be taken at one end at 180° intervals; when the length is greater than 2000mm (excluding the extended section of the sample material), one set of specimens shall be taken at both ends at 180° intervals. 4.2.3 If a double-length forging is split after heat treatment, it shall be regarded as one forging, and the number of specimens shall be in accordance with the provisions of 4.2.1 and 4.2.2. 4.2.4 The purchaser may also increase the number of specimens according to the use conditions of the forgings, but it shall be clearly specified in the contract or drawing. 4.3 Sampling position
4.3.1 The manufacturer shall reserve sufficient extended sections on the forgings for taking specimens. 4.3.2 If the diameter or the short side length of the end face of the forging is equal to or less than 100mm, the sample shall be taken from the extended section at the end. 4.3.3 If the diameter or the short side length of the end face of the forging is greater than 100mm, the sampling position shall be specified as follows, and see Figure 1. a) For solid circular shaft forgings, the sampling position shall be taken from the point where the end face of the extended section is one-third of the radius from the outer cylindrical surface. h) For solid polygonal shaft forgings, the sampling position shall be taken from the point where the end face of the extended section is one-sixth of the diagonal from the outer surface. c) For cylinder and ring forgings, the sampling position shall be taken from one-third of the wall thickness of the end face of the extended section. d) For solid disk forgings, the sampling position shall be taken from the outer circumference of the end face of the extended section. For such forgings, the purchaser shall clearly specify the location of the extended section in the contract, technical agreement or drawing, otherwise it shall be determined by the manufacturer. 4.3.4 If it is a random inspection piece of a batch of forgings, and it is not appropriate to reserve the extended section of the sample area, the manufacturer may destroy the forging to take samples, and the sampling regulations shall still be implemented in accordance with 4.3.2 and 4.3.3.
4.3.5 The manufacturer may decide to provide another forging to replace the extension, but the forging shall be made from the same furnace of molten steel, forged in the same way, with the same forging ratio, have the same dimensions as the replaced extension, and be heat treated in the same furnace as the delivered forging. The sampling provisions shall still be implemented in accordance with 4.3.2 and 4.3.3. 321
JB/T8421
a Longitudinal-end/one group
b Tangential/one end/one group
Longitudinal/two ends/each group
d Tangential/two ends/each group
Longitudinal end group
Longitudinal/two ends/each
Tangential/one end/one group
One end/one group
Tangential,-
8 Longitudinal/one end/one group Tangential/two ends/each group Figure 1A Schematic diagram of casting sampling position and specimen direction (shaft forgings) JB/T 8421
hLongitudinal/two ends/each groupTangential/two ends/each-groupFigure 1A (end)
Longitudinal/end/one group
Longitudinal/two ends/each
Tangential/two ends/each
Longitudinal end
Tangential end/group
hTangential.end·group
Figure 1BSchematic diagram of sampling position and specimen direction of forgings (simple forgings)aTangential/end/—group
Figure 1C Schematic diagram of sampling position and specimen direction of forgings (ring forgings)323
JB/T 8421
b Tangential/one end/two groups
Tangential/two ends/one group each
Figure 1C (end)
Tangential/one end·group
b Tangential/end/two groups
Tangential/two ends/each group
Figure 1D Schematic diagram of sampling position and specimen direction of forgings (disc forgings) Note: The dot-dash line in the figure is an extended section.
JB/T8421-96
4.3.6 Hardness test should be carried out on the forging surface L, as follows: a) For shaft, rod and tube forgings, when the length is equal to or less than 2000mm, one measurement should be made; when the length is greater than 2000mm, one measurement should be made at each end.
b) For ring and disc forgings, when the outer diameter is equal to or less than 1000mm, the test should be conducted at - locations; when the outer diameter is greater than 1000mm, the test should be conducted at - locations 180° apart.
If it is not appropriate to measure the hardness on the surface of the forging, it may be allowed to measure on the tensile test specimen or impact test specimen of the forging. 4.4 Test specimen direction
4.4.1 The test specimen direction shall be the main deformation direction of the forging, see Figure 1. a) For shafts, cylinders and forgings that are mainly subjected to elongation deformation, the direction of the tensile and impact test specimens shall be longitudinal. bh) For rings, discs and forgings that are mainly subjected to rough deformation, the direction of the tensile and impact test specimens shall be tangential. 4.4.2 For forgings that are required to take longitudinal test specimens according to 4.4.1, tangential test specimens (see Figure 1) may also be taken after consultation between the supplier and the buyer, but the mechanical property values shall be lower than the longitudinal specified values. The mechanical property values shall be determined by negotiation between the supplier and the buyer based on the smelting method, forging ratio, heat treatment method and the size of the extended section of the sample area of the forging. 4.5 Retest
4.5.1 If the performance value of a sample fails to meet the specified requirements due to a failure of the test equipment, incorrect sample preparation, or scratches unrelated to the material, the sample shall be discarded and a new sample may be taken at an adjacent position of the sample in the forging. 4.5.2 During the tensile test, if the sample breaks outside the gauge length or at a distance beyond half the distance from the gauge length center to the gauge length point, and the test results do not meet the specified requirements, the sample shall be invalid and a new sample may be taken at an adjacent position of the sample in the forging. 4.5.3 If the sample fails to meet the specified requirements not due to white spots or cracks in the forging, the forging may be retested without reheat treatment, and double samples may be taken at adjacent positions of the sample. Both samples shall meet the specified requirements. 4.6 Reheat treatment
4.6.1 If the strength performance index of the forging is high, but the plasticity and toughness indexes fail to meet the specified requirements, the forging can be supplemented with tempering, but there is no limit on the number of supplementary tempering. After tempering, the test shall be carried out according to the original regulations. 4.6.2 If the mechanical property test results of the forgings fail to meet the specified requirements, the manufacturer may re-heat treat the forgings and conduct tests according to the original regulations. Without the permission of the purchaser, the number of re-heat treatments shall not exceed two times. 4.7 Test methods
4.7.1 The tensile test method shall be in accordance with the provisions of GB228. 4.7.2 Punch test method, U-notch specimen shall be in accordance with the provisions of GB229, V-notch specimen shall be in accordance with the provisions of GB2106. 4.7.3 Hardness test method, Rockwell, Brinell, Shore hardness test, shall be in accordance with the provisions of GB/T230, GB231 and GB4341 respectively. 5 Other inspection items
The manufacturer shall conduct inspection only when the purchaser has made requirements for one or more of the following inspection items in the contract, technical agreement or drawings, and after the purchaser and the manufacturer have agreed.
5.1 In the case of low-power inspection, the sampling location and acceptance level shall be clearly stated for each inspection. The inspection methods are as follows: a) The low-magnification inspection method shall be in accordance with the provisions of GB226, and the evaluation method shall be in accordance with the provisions of GB1979. b) The fracture inspection and evaluation methods shall be in accordance with the provisions of GB1814 and GB2971. ) The evaluation method of combing inspection shall be in accordance with the provisions of (GB4236. 5.2 During high-magnification inspection, the sampling location and acceptance level shall be clearly specified for each inspection. The test methods are as follows: a) The microstructure inspection method shall be in accordance with the provisions of GB/T13298, and the evaluation method shall be in accordance with the provisions of GB/T13299. b) The grain size determination method shall be in accordance with the provisions of GB6394. c) The evaluation method of non-metallic inclusions shall be in accordance with the provisions of GB10561. 5.3 During ultra-Luper flaw detection, the flaw detection location, range, depth, flaw detection method and acceptance conditions shall be clearly specified. The test method can refer to the provisions of JB4009.
JB/T8421-96
5.4 The white spot inspection can be carried out on a specially cut test piece, or on the forging body by any method that can ensure the reliability of the inspection. If white spots are found in the sampled forgings, the batch of forgings should be inspected piece by piece. 6 Appearance quality
6.1 There shall be no defects such as cracks, shrinkage holes, folds, interlayers, etc. on the surface of forgings. 6.2 Surface defects of forgings are allowed to be repaired and removed, but they shall comply with the following provisions 6.2.1 The maximum depth of the repaired part of the non-machined surface of the forging shall not exceed the lower deviation of the size at that place, and the repaired part must have a smooth transition. 6.2.2 For the surface of forgings that need to be machined, after repair, it should be ensured that 50% of the nominal single-sided allowance is left at that place, and the repaired part must have a smooth transition.
6.2.3 After the defect is repaired, it should be inspected to confirm that the defect has been completely removed. 6.3 When the surface defects of forgings exceed the requirements of 6.2.1 or 6.2.2, except for forgings that are clearly specified in the material standards as weldable, forgings of other materials shall be welded with the consent of the purchaser. After the manufacturer thoroughly removes the defects in accordance with the provisions of 6.2.3, it shall use appropriate welding technology to weld. After welding, it shall be inspected by magnetic particle inspection or penetrant inspection, and ultrasonic testing shall be used when necessary to ensure the quality of the welded area. 6.4 The magnetic particle inspection method shall be in accordance with the provisions of ZBJ04006, and the penetrant inspection method shall be in accordance with the provisions of ZBJ04005. 7 Shape and size
The shape and size of forgings that have not been machined shall comply with the provisions of ZBJ32003 and GB/T15826 when delivered. 7.2
Forgings delivered in a rough-machined state, the deviation of the unmarked dimensional tolerance shall comply with the provisions of Table 3 and Table 4 unless otherwise specified in the contract. Table 3 Deviation of rough-machined forgings without dimensional tolerances 10.1 Nominal size 1 ≥ 1 000 > 2 000 ≥ 12 000 ≥ 4 000 ≥ 1 ≥ 8 000 1 16 000 The deviation of fillet radius and chamfer height of rough-machined forgings > 3 to 6 > 6 to 30 The dimensions of forgings delivered in the rough-machined and final heat-treated state shall conform to the dimensions on the drawing. 7.3
8 Marking
~12 000
30～120
~16 000
≥120～400
8.1 Forgings that pass the inspection shall be marked. The marking content may include: manufacturer's mark, work order number or joint number, steel grade, furnace number, forging number.
8.2 Medium-sized forgings shall be marked at the designated location of the drawing or process. If not specified, the location may be determined by the manufacturer. 8.3 Small batch forgings may be marked by hanging tags in batches. The tags may be made of thin steel plates or thin aluminum plates, on which the standard state is printed or the mark is written with paint.
9 Quality certificate
9.1 The manufacturer shall provide the purchaser with a quality certificate of the inspection results of each item of this standard. 9.2 The contents of the quality certificate shall include:
a) manufacturing name;
b) contract number;
c) drawing number and part name;
d) steel grade;
e) melting furnace number;
f) forging number or serial number;
g) heat treatment status;
h) main dimensions of forgings;
i) batch number and quantity of forgings;
i) inspection items and results,
k) inspection conclusion.
JB/T 8421-96
A1 Explanation of weighted average analysis method
JB/T 8421—96
Appendix A
(Appendix of the standard)
Weighted average analysis method
Weighted average analysis is a scientific calculation method. In this standard, it is applicable to steel ingots cast from two furnaces or two furnaces with molten steel. Assuming that the absolute content of a certain element in the steel ingot is the sum of the absolute contents of the element in each furnace of the molten steel, the composition value of the element in the steel ingot can be calculated by the weight ratio of each furnace of steel to the steel ingot. A2 Example of weighted average analysis method
A2.1 Weight and chemical composition of molten steel from each furnace of the cast steel ingot The weight and chemical composition of molten steel from each furnace of a three-furnace cast steel ingot are shown in Table A1. Table A1 Weight and chemical composition of molten steel in each furnace of combined cast steel ingot Steelmaking furnace number
Molten steel weight
The weight of the combined cast steel ingot is 125t.
Determine the weight of the molten steel of each furnace (W.)
According to the ratio of the weight of the molten steel of each furnace to the weight of the ingot, determine the weight of the molten steel of each furnace: W, weight of the first molten steel × 100%
weight of the ingot
According to Table A1, obtain:
Furnace No. 1: W, = (25/125) × 100% = 20%
Furnace No. 2: Wz = (50/125) X100% = 40%
Furnace No. 3 W = (50/125) X100% = 40%
A2.3 Calculate the weighted average value of the content of each element in the ingot.
The weighted average value of the content of a certain element (%) is equal to the sum of the products of the content of the element (%) in the molten steel of each furnace and the weight W. Taking carbon content as an example, according to the weights of molten steel from each furnace obtained in Tables A1 and A2.2, we can calculate: Furnace No. 1: 0.20×20%=0.04
Furnace No. 2: 0.25×40%0.10
Furnace No. 3: 0.25×40%-0.10
Then the weighted average carbon content (%) of this steel ingot is 0.04+0.10-+-0.10=0.24. Take manganese content as an example:
Furnace No. 1: 0.50×20%=0.10
Furnace No. 2: 0.50×40%=0.20
Furnace No. 3: 0.50×40%=0.20
The weighted average of manganese content (%) is 0.10+0.20+0.20=0.50.2 During high-power inspection, the sampling location and acceptance level shall be clearly defined for each inspection. The test methods are as follows: a) The microstructure inspection method shall be in accordance with the provisions of GB/T13298, and the evaluation method shall be in accordance with the provisions of GB/T13299. b) The grain size determination method shall be in accordance with the provisions of GB6394. c) The evaluation method of non-metallic inclusions shall be in accordance with the provisions of GB10561. 5.3 During ultra-Luper flaw detection, the flaw detection location, range, depth, flaw detection method and acceptance conditions shall be clearly defined. The test method can refer to the provisions of JB4009.
JB/T8421-96
5.4 White spot inspection can be carried out on a specially cut test piece, or on the forging body using any method that can ensure the reliability of the inspection. If white spots are found in the sampled forgings, the batch of forgings shall be inspected piece by piece. 6 Appearance quality
6.1 There shall be no defects such as cracks, shrinkage holes, folds, and interlayers on the surface of the forgings. 6.2 Repair and removal of surface defects of forgings are allowed, but they shall comply with the following provisions: 6.2.1 The maximum depth of the repaired area of the non-machined surface of the forging shall not exceed the lower deviation of the size at that location, and the repaired area must have a smooth transition. 6.2.2 For the surface of forgings that need to be machined, 50% of the nominal single-sided allowance shall be left after repair, and the repaired area must have a smooth transition.
6.2.3 After the defects are repaired, they shall be inspected to confirm that the defects have been completely removed. 6.3 When the surface defects of forgings exceed the provisions of 6.2.1 or 6.2.2, except for forgings that are clearly specified in the material standards as weldable, forgings of other materials: If welding repair is required, the purchaser shall agree. After the manufacturer has completely removed the defects in accordance with the provisions of 6.2.3, it shall use a suitable welding repair process for welding repair. After welding repair, it shall be inspected by magnetic particle inspection or penetrant inspection, and ultrasonic probing inspection shall be used if necessary to ensure the quality of the weld repair area. 6.4 The magnetic particle inspection method shall comply with the provisions of ZBJ04006, and the penetrant inspection method shall comply with the provisions of ZBJ04005. 7 Shape and size
Forgings that have not been machined shall comply with the provisions of ZBJ32003 and GB/T15826 when delivered. 7.2
Forgings delivered in a rough-machined state, the deviation of the unmarked dimensional tolerance shall comply with the provisions of Table 3 and Table 4 unless otherwise specified in the contract. Table 3 Deviation of rough-machined forgings without specified dimensional tolerances Nominal deviation 10.1 Nominal size 1 ≥ 1 000 > 2 000 ≥ 12 000 ≥ 4 000 ≥ 1 ≥ 8 000 11 6 000 The deviation of fillet radius and chamfer height of rough-machined forgings > 3 to 6 > 6 to 30 The dimensions of forgings delivered in the rough-machined and final heat-treated state shall conform to the dimensions on the drawing. 7.3
8 Marking
~12 000
30～120
~16 000
≥120～400
8.1 Forgings that have passed the inspection shall be marked. The marking content may include: manufacturer's mark, work order number or joint number, steel grade, furnace number, forging number.
8.2 Medium-sized forgings shall be marked at the designated location of the drawing or process. If not specified, the location may be determined by the manufacturer. 8.3 Small batch forgings may be marked by hanging tags in batches. The tags may be made of thin steel plates or thin aluminum plates, on which the standard state is printed or the mark is written with paint.
9 Quality certificate
9.1 The manufacturer shall provide the purchaser with a quality certificate of the inspection results of each item of this standard. 9.2 The contents of the quality certificate should include:
a) manufacturing name;
b) contract number;
c) drawing number and part name;
d) steel grade;
e) melting furnace number;
f) forging number or serial number;
g) heat treatment status;
h) main dimensions of forgings;
i) batch number and quantity of forgings;
i) inspection items and results,
k) inspection conclusion.
JB/T 8421-96
A1 Explanation of weighted average analysis method
JB/T 8421-96
Appendix A
(Appendix of the standard)
Weighted average analysis method
Weighted average analysis is a scientific calculation method. In this standard, it is applicable to steel ingots cast from two furnaces or two furnaces with molten steel. Assuming that the absolute content of a certain element in the steel ingot is the sum of the absolute contents of the element in each furnace of the molten steel, the composition value of the element in the steel ingot can be calculated by the weight ratio of each furnace of steel to the steel ingot. A2 Example of weighted average analysis method
A2.1 Weight and chemical composition of molten steel from each furnace of the cast steel ingot The weight and chemical composition of molten steel from each furnace of a three-furnace cast steel ingot are shown in Table A1. Table A1 Weight and chemical composition of molten steel in each furnace for combined cast ingot Steelmaking furnace number
Weight of molten steel
The weight of combined cast ingot is 125t.
Determine the weight of the molten steel of each furnace (W.)
According to the ratio of the weight of the molten steel of each furnace to the weight of the ingot, determine the weight of the molten steel of each furnace: W, weight of the first molten steel × 100%
weight of the ingot
According to Table A1, obtain:
Furnace No. 1: W, = (25/125) × 100% = 20%
Furnace No. 2: Wz = (50/125) X100% = 40%
Furnace No. 3 W = (50/125) X100% = 40%
A2.3 Calculate the weighted average value of the content of each element in the ingot.
The weighted average value of the content of a certain element (%) is equal to the sum of the products of the content of the element (%) in the molten steel of each furnace and the weight W. Taking carbon content as an example, according to the weights of molten steel from each furnace obtained in Tables A1 and A2.2, we can calculate: Furnace No. 1: 0.20×20%=0.04
Furnace No. 2: 0.25×40%0.10
Furnace No. 3: 0.25×40%-0.10
Then the weighted average carbon content (%) of this steel ingot is 0.04+0.10-+-0.10=0.24. Take manganese content as an example:
Furnace No. 1: 0.50×20%=0.10
Furnace No. 2: 0.50×40%=0.20
Furnace No. 3: 0.50×40%=0.20
The weighted average of manganese content (%) is 0.10+0.20+0.20=0.50.2 During high-power inspection, the sampling location and acceptance level shall be clearly defined for each inspection. The test methods are as follows: a) The microstructure inspection method shall be in accordance with the provisions of GB/T13298, and the evaluation method shall be in accordance with the provisions of GB/T13299. b) The grain size determination method shall be in accordance with the provisions of GB6394. c) The evaluation method of non-metallic inclusions shall be in accordance with the provisions of GB10561. 5.3 During ultra-Luper flaw detection, the flaw detection location, range, depth, flaw detection method and acceptance conditions shall be clearly defined. The test method can refer to the provisions of JB4009.
JB/T8421-96
5.4 White spot inspection can be carried out on a specially cut test piece, or on the forging body using any method that can ensure the reliability of the inspection. If white spots are found in the sampled forgings, the batch of forgings shall be inspected piece by piece. 6 Appearance quality
6.1 There shall be no defects such as cracks, shrinkage holes, folds, and interlayers on the surface of the forgings. 6.2 Repair and removal of surface defects of forgings are allowed, but they shall comply with the following provisions: 6.2.1 The maximum depth of the repaired area of the non-machined surface of the forging shall not exceed the lower deviation of the size at that location, and the repaired area must have a smooth transition. 6.2.2 For the surface of forgings that need to be machined, 50% of the nominal single-sided allowance shall be left after repair, and the repaired area must have a smooth transition.
6.2.3 After the defects are repaired, they shall be inspected to confirm that the defects have been completely removed. 6.3 When the surface defects of forgings exceed the provisions of 6.2.1 or 6.2.2, except for forgings that are clearly specified in the material standards as weldable, forgings of other materials: If welding repair is required, the purchaser shall agree. After the manufacturer has completely removed the defects in accordance with the provisions of 6.2.3, it shall use a suitable welding repair process for welding repair. After welding repair, it shall be inspected by magnetic particle inspection or penetrant inspection, and ultrasonic probing inspection shall be used if necessary to ensure the quality of the weld repair area. 6.4 The magnetic particle inspection method shall comply with the provisions of ZBJ04006, and the penetrant inspection method shall comply with the provisions of ZBJ04005. 7 Shape and size
Forgings that have not been machined shall comply with the provisions of ZBJ32003 and GB/T15826 when delivered. 7.2
Forgings delivered in a rough-machined state, the deviation of the unmarked dimensional tolerance shall comply with the provisions of Table 3 and Table 4 unless otherwise specified in the contract. Table 3 Deviation of rough-machined forgings without dimensional tolerances 10.1 Nominal size 1 ≥ 1 000 > 2 000 ≥ 12 000 ≥ 4 000 ≥ 1 ≥ 8 000 1 16 000 The deviation of fillet radius and chamfer height of rough-machined forgings > 3 to 6 > 6 to 30 The dimensions of forgings delivered in the rough-machined and final heat-treated state shall conform to the dimensions on the drawing. 7.3
8 Marking
~12 000
30～120
~16 000
≥120～400
8.1 Forgings that pass the inspection shall be marked. The marking content may include: manufacturer's mark, work order number or joint number, steel grade, furnace number, forging number.
8.2 Medium-sized forgings shall be marked at the designated location of the drawing or process. If not specified, the location may be determined by the manufacturer. 8.3 Small batch forgings may be marked by hanging tags in batches. The tags may be made of thin steel plates or thin aluminum plates, on which the standard state is printed or the mark is written with paint.
9 Quality certificate
9.1 The manufacturer shall provide the purchaser with a quality certificate of the inspection results of each item of this standard. 9.2 The contents of the quality certificate shall include:
a) manufacturing name;
b) contract number;
c) drawing number and part name;
d) steel grade;
e) melting furnace number;
f) forging number or serial number;
g) heat treatment status;
h) main dimensions of forgings;
i) batch number and quantity of forgings;
i) inspection items and results,
k) inspection conclusion.
JB/T 8421-96
A1 Explanation of weighted average analysis method
JB/T 8421—96
Appendix A
(Appendix of the standard)
Weighted average analysis method
Weighted average analysis is a scientific calculation method. In this standard, it is applicable to steel ingots cast from two furnaces or two furnaces with molten steel. Assuming that the absolute content of a certain element in the steel ingot is the sum of the absolute contents of the element in each furnace of the molten steel, the composition value of the element in the steel ingot can be calculated by the weight ratio of each furnace of steel to the steel ingot. A2 Example of weighted average analysis method
A2.1 Weight and chemical composition of molten steel from each furnace of the cast steel ingot The weight and chemical composition of molten steel from each furnace of a three-furnace cast steel ingot are shown in Table A1. Table A1 Weight and chemical composition of molten steel in each furnace for combined cast ingot Steelmaking furnace number
Weight of molten steel
The weight of combined cast ingot is 125t.
Determine the weight of the molten steel of each furnace (W.)
According to the ratio of the weight of the molten steel of each furnace to the weight of the ingot, determine the weight of the molten steel of each furnace: W, weight of the first molten steel × 100%
weight of the ingot
According to Table A1, obtain:
Furnace No. 1: W, = (25/125) × 100% = 20%
Furnace No. 2: Wz = (50/125) X100% = 40%
Furnace No. 3 W = (50/125) X100% = 40%
A2.3 Calculate the weighted average value of the content of each element in the ingot.
The weighted average value of the content of a certain element (%) is equal to the sum of the products of the content of the element (%) in the molten steel of each furnace and the weight W. Taking carbon content as an example, according to the weights of molten steel from each furnace obtained in Tables A1 and A2.2, we can calculate: Furnace No. 1: 0.20×20%=0.04
Furnace No. 2: 0.25×40%0.10
Furnace No. 3: 0.25×40%-0.10
Then the weighted average carbon content (%) of this steel ingot is 0.04+0.10-+-0.10=0.24. Take manganese content as an example:
Furnace No. 1: 0.50×20%=0.10
Furnace No. 2: 0.50×40%=0.20
Furnace No. 3: 0.50×40%=0.20
The weighted average of manganese content (%) is 0.10+0.20+0.20=0.50.1
Nominal size
1≥1 000
>2 000
≥12 000
≥4 000
1≥8 000
116 000
Rough forgings Radius and chamfer height deviation>3～6
>6～30
Forgings delivered in rough and final heat treatment state shall conform to the dimensions on the drawing. 7.3
8 Marking
~12 000
30～120
~16 000
≥120～400
8.1 Forgings that pass the inspection shall be marked. The marking content may include: manufacturer's mark, work order number or workshop number, steel grade, furnace number, forging number.
8.2 Medium-sized forgings shall be marked at the designated location of the drawing or process. If not specified, the location may be determined by the manufacturer. 8.3 Small batch forgings may be marked by hanging tags in batches. The tags may be made of thin steel plates or thin aluminum plates, on which the marking state is printed or painted.
9 Quality Certificate
9.1 The manufacturer shall provide the purchaser with a quality certificate of the test results of this standard. 9.2 The contents of the quality certificate should include:
a) manufacturing name;
b) contract number;
c) drawing number and part name;
d) steel grade;
e) melting furnace number;
f) forging number or serial number;
g) heat treatment status;
h) main dimensions of forgings;
i) batch number and quantity of forgings;
i) inspection items and results,
k) inspection conclusion.
JB/T 8421-96
A1 Explanation of weighted average analysis method
JB/T 8421-96
Appendix A
(Appendix of the standard)
Weighted average analysis method
Weighted average analysis is a scientific calculation method. In this standard, it is applicable to steel ingots cast from two furnaces or two furnaces with molten steel. Assuming that the absolute content of a certain element in the steel ingot is the sum of the absolute contents of the element in each furnace of the molten steel, the composition value of the element in the steel ingot can be calculated by the weight ratio of each furnace of steel to the steel ingot. A2 Example of weighted average analysis method
A2.1 Weight and chemical composition of molten steel from each furnace of the cast steel ingot The weight and chemical composition of molten steel from each furnace of a three-furnace cast steel ingot are shown in Table A1. Table A1 Weight and chemical composition of molten steel in each furnace for combined cast ingot Steelmaking furnace number
Weight of molten steel
The weight of combined cast ingot is 125t.
Determine the weight of the molten steel of each furnace (W.)
According to the ratio of the weight of the molten steel of each furnace to the weight of the ingot, determine the weight of the molten steel of each furnace: W, weight of the first molten steel × 100%
weight of the ingot
According to Table A1, obtain:
Furnace No. 1: W, = (25/125) × 100% = 20%
Furnace No. 2: Wz = (50/125) X100% = 40%
Furnace No. 3 W = (50/125) X100% = 40%
A2.3 Calculate the weighted average value of the content of each element in the ingot.
The weighted average value of the content of a certain element (%) is equal to the sum of the products of the content of the element (%) in the molten steel of each furnace and the weight W. Taking carbon content as an example, according to the weights of molten steel from each furnace obtained in Tables A1 and A2.2, we can calculate: Furnace No. 1: 0.20×20%=0.04
Furnace No. 2: 0.25×40%0.10
Furnace No. 3: 0.25×40%-0.10
Then the weighted average carbon content (%) of this steel ingot is 0.04+0.10-+-0.10=0.24. Take manganese content as an example:
Furnace No. 1: 0.50×20%=0.10
Furnace No. 2: 0.50×40%=0.20
Furnace No. 3: 0.50×40%=0.20
The weighted average of manganese content (%) is 0.10+0.20+0.20=0.50.1
Nominal size
1≥1 000
>2 000
≥12 000
≥4 000
1≥8 000
116 000
Rough forgings Radius and chamfer height deviation>3～6
>6～30
Forgings delivered in rough and final heat treatment state shall conform to the dimensions on the drawing. 7.3
8 Marking
~12 000
30～120
~16 000
≥120～400
8.1 Forgings that pass the inspection shall be marked. The marking content may include: manufacturer's mark, work order number or workshop number, steel grade, furnace number, forging number.
8.2 Medium-sized forgings shall be marked at the designated location of the drawing or process. If not specified, the location may be determined by the manufacturer. 8.3 Small batch forgings may be marked by hanging tags in batches. The tags may be made of thin steel plates or thin aluminum plates, on which the marking state is printed or painted.
9 Quality Certificate
9.1 The manufacturer shall provide the purchaser with a quality certificate of the test results of this standard. 9.2 The contents of the quality certificate should include:
a) manufacturing name;
b) contract number;
c) drawing number and part name;
d) steel grade;
e) melting furnace number;
f) forging number or serial number;
g) heat treatment status;
h) main dimensions of forgings;
i) batch number and quantity of forgings;
i) inspection items and results,
k) inspection conclusion.
JB/T 8421-96
A1 Explanation of weighted average analysis method
JB/T 8421-96
Appendix A
(Appendix of the standard)
Weighted average analysis method
Weighted average analysis is a scientific calculation method. In this standard, it is applicable to steel ingots cast from two furnaces or two furnaces with molten steel. Assuming that the absolute content of a certain element in the steel ingot is the sum of the absolute contents of the element in each furnace of the molten steel, the composition value of the element in the steel ingot can be calculated by the weight ratio of each furnace of steel to the steel ingot. A2 Example of weighted average analysis method
A2.1 Weight and chemical composition of molten steel from each furnace of the cast steel ingot The weight and chemical composition of molten steel from each furnace of a three-furnace cast steel ingot are shown in Table A1. Table A1 Weight and chemical composition of molten steel in each furnace for combined cast ingot Steelmaking furnace number
Weight of molten steel
The weight of combined cast ingot is 125t.
Determine the weight of the molten steel of each furnace (W.)
According to the ratio of the weight of the molten steel of each furnace to the weight of the ingot, determine the weight of the molten steel of each furnace: W, weight of the first molten steel × 100%
weight of the ingot
According to Table A1, obtain:
Furnace No. 1: W, = (25/125) × 100% = 20%
Furnace No. 2: Wz = (50/125) X100% = 40%
Furnace No. 3 W = (50/125) X100% = 40%
A2.3 Calculate the weighted average value of the content of each element in the ingot.
The weighted average value of the content of a certain element (%) is equal to the sum of the products of the content of the element (%) in the molten steel of each furnace and the weight W. Taking carbon content as an example, according to the weights of molten steel from each furnace obtained in Tables A1 and A2.2, we can calculate: Furnace No. 1: 0.20×20%=0.04
Furnace No. 2: 0.25×40%0.10
Furnace No. 3: 0.25×40%-0.10
Then the weighted average carbon content (%) of this steel ingot is 0.04+0.10-+-0.10=0.24. Take manganese content as an example:
Furnace No. 1: 0.50×20%=0.10
Furnace No. 2: 0.50×40%=0.20
Furnace No. 3: 0.50×40%=0.20
The weighted average of manganese content (%) is 0.10+0.20+0.20=0.50.
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