JB/T 7028-1993 Technical requirements for turbine discs and impeller forgings below 25MW
Some standard content:
Machinery Industry Standard of the People's Republic of China
JB/T 7028-93
Technical conditions for discs and impeller forgings for steam turbines below 25MW
Published on September 21, 1993
Ministry of Machinery Industry of the People's Republic of China
Implementation on July 1, 1994
Mechanical Industry Standard of the People's Republic of China
Technical conditions for discs and impeller forgings for steam turbines below 25MW
1 Subject content and scope of application
JB/T 7028-93
This standard specifies the technical requirements, inspection rules, test methods, certificates and marks of carbon steel and alloy steel plated parts for discs and impellers of steam turbines below 25MW.
This standard applies to the ordering, manufacturing and inspection of carbon steel and alloy steel forgings for discs and impellers of steam turbines below 25MW. 2 Reference standards
GB4236
GB6394
GB 6395
GB6397
GB10561
JB1581
JB/ZQ6101
JB/ZQ6134
3 Ordering requirements
Steel chemical analysis sample sampling method and finished product chemical composition allowable deviation Pin iron and alloy chemical analysis method
Metal tensile test method
Metal composite (U-notch) impact test method Metal Brinell hardness test method
Metal bending test method
Steel Sulfur print test
Method for determining average particle size of metal
Method for high temperature tensile endurance test of metal
Metal tensile test specimen
Microscopic evaluation method for non-metallic inclusions in steelUltrasonic flaw detection method for plated parts of turbine and turbine generator rotor and main shaftMagnetic particle inspection method for forged steel parts
Sulfur print test method and evaluation for plated parts of large shafts3.1 The purchaser shall specify the adopted standard, steel grade, forging grade, corresponding technical requirements, inspection items and inspection items other than those required by this standard in the order contract or technical agreement.
3.2 The purchaser shall provide the order drawing of forgings indicating the sampling position for mechanical property test. 4 Technical requirements
4.1 Manufacturing process
4.1.1 Smelting
4.1.1.1 The steel for plated parts shall be smelted in an alkaline electric furnace. 4.1.1.2 With the consent of the purchaser, other smelting methods that can ensure the requirements of this standard are allowed. 4.1.2 Forging
4.1.2.1 The steel ingots used for forgings shall have sufficient cuts to ensure that the finished forgings have no shrinkage cavities and unacceptable segregation. 4.1.2.2 The entire cross section shall be fully forged. The axial height of the forging before roughening shall be at least twice the thickness of the forging. Approved by the Ministry of Machinery Industry on September 21, 1993
Implementation on July 1, 1994
4.1.3 Heat treatment
JB/T7028-93
4.1.3.1 Forgings shall be normalized or annealed after silvering. 4.1.3.2 Performance heat treatment (quenching and tempering treatment should be carried out after each rough machining. For die forgings with a wheel section thickness of less than 150mm, the rough parts can be tempered after eliminating surface defects. 4.1.3.3 The furnace temperature must be uniform during heat treatment and kept warm for a sufficient time to austenitize. Then cool it appropriately to make it completely change phase. Carbon steel forgings are water-cooled and alloy steel plated parts are oil-cooled. 4.1.3.4 Under the condition of meeting the mechanical properties, the tempering temperature should be as high as possible to ensure that the plated parts have stable performance. The tempering cooling rate of silver parts should not be greater than 25℃/h to minimize residual stress. 4.1.4 Machining
4.1.4.1 Performance Before heat treatment, all surfaces of the parts should be rough-machined and mechanical properties should be left at the specified positions. 4.1.4.2 The size and surface roughness after rough machining shall comply with the requirements of the order drawing or rough machining drawing. 4.2 Steel type and chemical composition
Unless otherwise specified in the contract, the smelting analysis results of the steel shall comply with the provisions of Table 1. The finished product analysis and results of the forgings shall comply with the provisions of Table 1. Under the condition that the mechanical properties are qualified, the deviation specified in Table 2 of GB222 is allowed.
Table 1 Chemical composition
34CrMo
34CrMo1
24CrMoV
35CrMoV
34CrNi3Mo
25CrNiMoV
Mechanical properties
JB/T 7028-93
Unless otherwise specified, the mechanical properties of silver parts shall comply with the provisions of Table 2. Table 2 Mechanical properties
Bending angle
Number of surface thickness
Recommended surface thickness
Note: The scattered surface thickness is for reference,
4.4 Hardness uniformity
≥440
34CrMo
35CrMoV
≤250
34CrMo
34CrMo1
24CrMoV
35CrMoV
≥690
≤200
34CrMol
35CrMoV
≥720
24CrMoV
34CrMo1
35CrMoV
≥690
760~900
810~950
25CrNiMoV34CrMi3Mo
≥730
850~970
34CrNi2Mo
The hardness difference between the rim and the hub should not exceed 40HRS. The hardness difference between the rim or the hub should not exceed 30HBS. The absolute value of hardness is for reference only.
4.5 Residual stress
For forgings with a diameter of 600~1000mm after finishing, the residual stress should not be greater than 40MPa. For forgings with a diameter greater than 1000mm, the residual stress should not be greater than 50MPa.
4.6 Cold bending test
The buyer has the right to conduct cold bending test. The supplier does not conduct this test. However, the results shall be in accordance with the provisions of Table 2. 4.7 Nondestructive testing
4.7.1 Forgings are not allowed to have defects such as cracks, white spots, shrinkage holes, etc. 4.7.2 Pickling or magnetic particle testing
Unless otherwise specified, the supplier shall ensure that for each inspection part, no more than 12 defects with an equivalent diameter of less than 2 mm are displayed, and no more than 5 defects with an equivalent diameter of 2~4 mm are displayed. 4.7.3 Ultrasonic testing
Unless otherwise specified, ultrasonic testing shall comply with the following provisions: 4. 7. 3. 1
4.7. 3. 2
Single scattered defects with an equivalent diameter of less than 2 mm are not counted. Scattered defects with an equivalent diameter of 2~4 mm are allowed, but no more than 10 defects are displayed in an area of 100cm. 4.7.3.3 It is allowed to have dense areas with an equivalent diameter not exceeding 2mm. The area of each dense area shall not be greater than 4cm. The height between each dense area shall not be less than 120mm. The number of dense areas shall not exceed 3. 4.7.4 Defects beyond the above provisions can be removed by local grinding in the grinding area, but the grinding depth shall not exceed 1.5mm, and the transition with the surrounding surface shall be smooth. If it cannot be removed, the two parties shall negotiate. 4.8 Grain size
When the grain size inspection is required, it shall be indicated in the order contract. Unless otherwise specified, the average product grain size shall not be coarser than grade 4.0. 4.9 Sulfur print test
The buyer has the right to conduct sulfur print inspection. The supplier does not conduct this inspection. However, it shall ensure that the result is not greater than grade 3. If it is greater than grade 3, the two parties shall negotiate 3
.
5 Inspection rules and test methods
5.1 Chemical composition analysis
5.1.1 Melting analysis shall be carried out for each furnace of molten steel. JB/T7028-93
5.1.2 The sample for product analysis is taken from the mechanical properties test ring, or from the performance sample. 5.1.3 The sampling of chemical analysis samples shall be in accordance with GB222. 5.1.4 The chemical composition analysis shall be in accordance with GB223 or other analysis methods that ensure the quality of the analysis. 5.2 Mechanical properties
5.2.1 Performance heat treatment Mechanical properties test shall be carried out piece by piece. 5.2.2-When the inner diameter of the wheel disc is less than 250mm, the sample is taken from the end of the wheel hub or the outer four of the wheel hub. When the inner diameter of the wheel disc is greater than or equal to 250mm, the sample is taken from the inner wall of the wheel hole.
5.2.3 Each set of specimens shall have 1 tensile specimen, 2 impact specimens and 1 bending specimen. 5.2.4 The tensile test shall comply with the provisions of GB228, and the impact test shall comply with the provisions of GB229. 5.2.5 The preparation and cutting of tensile test specimens shall comply with the short proportion specimens specified in GB6397, and the impact test specimens shall comply with the provisions of GB229. 5.3 Hardness uniformity
5.3.1 Hardness uniformity inspection is carried out after performance heat treatment. 5.3.2 Inspection location: Measure two points on the two radials of the rim and the hub at 90° to each other. 5.3.3 Hardness inspection method shall comply with GB231. 5.4 Cold bending test
5.4.1 Take a 10mm×20mm×160mm sample in accordance with GB223. When sampling is difficult, a 6mm×12mm×12mm sample is allowed. The edge of the sample should be a circular arc with a radius of 1mm. The diameter of the bending core is 40mm. 5.4.2 Test method shall comply with GB232. 5.5 Nondestructive testing
5.5.1 Pickling or magnetic particle testing
5.5.1.1 Pickling or magnetic particle testing shall be carried out by the purchaser. Magnetic particle testing shall be carried out after fine processing, and pickling testing shall be carried out under the condition of leaving 1~2mm margin.
5.5.1.2 The magnetic particle testing area is the entire surface of the wheel. The pickling testing area is the wheel hole and the wheel segment end face, and the surface roughness R. value is 3.2um.
5.5.1.3 The magnetic particle testing method shall be in accordance with JB/2Q6101 or other recognized methods. 5.5.1.4 Pickling testing method
The surface roughness R. value of the pickling area is 1.6um. When pickling, first use 15% ammonium persulfate aqueous solution, then use 10% nitric acid aqueous solution, and wash the test surface. The pickling time shall not be less than 15min respectively. After pickling, two inspections are carried out. The first inspection is 10 minutes after pickling. The second inspection is not less than 12 hours after pickling. 5.5.2 Ultrasonic inspection
5.5.2.1 After the final heat treatment, the forgings shall be subjected to ultrasonic inspection on the hub (and the rim when necessary). The supplier shall not inspect the rim, but shall ensure that the results comply with the provisions of Article 4.7.3 of this standard. 5.5.2.2 Forgings that need to be reheat treated shall be subjected to ultrasonic inspection again after reheat treatment. 5.5.2.3 The ultrasonic inspection method shall comply with the provisions of JB1582. 5.6 Residual stress
5.6.1 When the diameter of the forging is greater than 600mm, the residual stress inspection shall be carried out after quenching and tempering. 5.6.2 Randomly select one piece from the batch of forgings heat treated in the same furnace (the purchaser shall conduct residual stress inspection on each forging), unless otherwise specified. The ring cutting method or the ring core resistance strain method shall be used. When cutting the mechanical properties test ring, the residual stress shall be inspected (the sample size is 25mmX25mm). The residual stress shall be calculated by measuring the average deformation of the ring before and after cutting. 4
5.6.3 Residual stress calculation formula
Where: a,——residual stress.MPa
3-algebraic value of diameter increment.mm
D-—outer diameter of the ring before cutting.mm;
E—elastic modulus of the material, MPa,
JB/T702893
a, =E/D
If the test does not meet the requirements, the batch of silver pieces shall be inspected for residual stress piece by piece or heat treated again according to Article 5.10.1 of this standard. 5.7 Dimensional inspection
Forging dimensions shall be inspected remotely according to the drawings. 5.8 Metallographic inspection
5.8.1 Unless otherwise specified, the sulfur print inspection method shall be in accordance with GB4236, and the grading shall be carried out in accordance with JB/ZQ6134. 5.8.2 Unless otherwise specified, the sample for measuring grain size shall be taken from the end face of the mechanical properties sample. The grain size inspection method shall be in accordance with GB6394. 5.9 Retest
5.9.1 Retest is allowed when the mechanical properties test results do not meet the specified requirements. However, retest is not allowed for samples that fail due to white spots or cracks. 5.9.2 When a test result fails due to equipment failure or poor sample preparation, samples can be taken from adjacent positions of the forging for retesting. 5.9.3 When one of the mechanical properties tests does not meet the requirements, two samples should be taken from adjacent positions for retesting, and the test results should meet the requirements.
5.10 Reheat treatment
5.10.1 If the residual stress test result is unqualified, stress relief treatment can be carried out again. The stress relief treatment temperature should be 20-50°C lower than the final heat treatment tempering temperature. Hardness test and residual stress test should be carried out after heat treatment. When the stress relief treatment temperature is less than 20°C lower than the final heat treatment tempering temperature, mechanical property test and residual stress test should be carried out piece by piece after heat treatment. When the mechanical property retest of forgings is unqualified, reheat treatment is allowed. After reheat treatment, samples should be taken again for mechanical property test. 5.10.2
The number of reheat treatments shall not exceed 3 for carbon steel and 2 for alloy steel. 6 Acceptance and certificate of conformity
The supplier shall provide the necessary convenient conditions for the purchaser's inspector to facilitate the purchaser's inspector to carry out his work. 6.1
6.2. The purchaser has the right to select certain acceptance test items for forgings. If it is found during the acceptance test or in subsequent processing or testing that the forgings do not meet the supplementary technical requirements specified in this standard and the order contract, the purchaser shall promptly notify the supplier and the two parties shall resolve the issue through consultation. 6.3 The supplier shall provide the purchaser with a certificate of conformity, which shall include the following: a.
Contract number,
Forging drawing number:
Standard number, plating grade and steel type:
Smelting furnace number and roasting method:
Smelting analysis and finished product analysis results:
Main dimensions of steel ingots and actual silver-to-metal ratio of forgings: Actual temperature, holding time and cooling method of each heat treatment; Test results of mechanical properties;
Ultrasonic test report:
Results of other tests and supplementary tests required by the purchaser; Actual dimensions and weight of the delivered forgings;
7 Marking and packaging
The supplier shall mark the contract number, melting furnace number, ingot section number, part number and factory name on the outer peripheral surface of the rim of each forging. The supplier shall pack the products according to the requirements of transportation. 7.2
Additional Notes:
JB/T7028-93
This standard is proposed and managed by Deyang Large Castings and Forgings Research Institute of the Ministry of Machinery Industry. This standard is drafted by Deyang Large Castings Research Institute. The main drafters of this standard are Jiang Xinliang, Li Wenhua, Pan Yixiang and Jiang Jie.=E/D
When the test does not meet the requirements, the batch of silver pieces shall be checked for residual stress piece by piece or heat treated again according to Article 5.10.1 of this standard. 5.7 Dimensional inspection
Forging dimensions shall be inspected remotely according to the drawings. 5.8 Metallographic inspection
5.8.1Unless otherwise specified, the sulfur print inspection method shall be in accordance with GB4236, and the rating shall be in accordance with JB/ZQ6134. 5.8.2Unless otherwise specified, the sample for measuring grain size shall be taken from the end face of the mechanical properties sample. The product grain size inspection method shall be in accordance with GB6394. 5.9 Retest
5.9.1Retest is allowed when the mechanical properties test results do not meet the specified requirements. However, if the sample fails due to white spots or cracks, retest is not allowed. 5.9.2 If a test result fails due to equipment failure or poor sample preparation, a sample can be taken from the adjacent position of the forging for retesting. 5.9.3 If one of the mechanical properties test does not meet the requirements, two samples should be taken from the adjacent position for retesting, and the test results should meet the requirements.
5.10 Reheat treatment
5.10.1 If the residual stress test result fails, stress removal treatment can be performed again. The stress removal treatment temperature should be 20~50C lower than the final heat treatment tempering temperature. After heat treatment, hardness test and residual stress test should be performed. When the stress removal treatment temperature is within 20℃ lower than the final heat treatment tempering temperature, mechanical property test and residual stress test should be performed piece by piece after heat treatment. When the mechanical property retest of the forging fails, reheat treatment is allowed. After reheat treatment, resampling should be performed for mechanical property test. 5.10.2
The number of reheat treatments shall not exceed 3 for carbon steel and 2 for alloy steel. 6 Acceptance and Certificate of Qualification
The supplier shall provide the necessary convenience to the purchaser's inspector so that the purchaser's inspector can carry out his work. 6.1
6.2. The purchaser has the right to select certain acceptance test items for forgings. If it is found in the acceptance test or in the subsequent processing or test that the forgings do not meet the supplementary technical requirements specified in this standard and the order contract, the purchaser shall promptly notify the supplier and the two parties shall negotiate to resolve the issue. 6.3 The supplier shall provide the purchaser with a certificate of conformity, which shall include the following: a.www.bzxz.net
Contract number,
Forging drawing number:
Standard number, plating grade and steel type:
Smelting furnace number and roasting method:
Smelting analysis and finished product analysis results:
Main dimensions of steel ingots and actual silver-to-metal ratio of forgings: Actual temperature, holding time and cooling method of each heat treatment; Test results of mechanical properties;
Ultrasonic test report:
Results of other tests and supplementary tests required by the purchaser; Actual dimensions and weight of the delivered forgings;
7 Marking and packaging
The supplier shall mark the contract number, melting furnace number, ingot section number, part number and factory name on the outer peripheral surface of the rim of each forging. The supplier shall pack the products according to the requirements of transportation. 7.2
Additional Notes:
JB/T7028-93
This standard is proposed and managed by Deyang Large Castings and Forgings Research Institute of the Ministry of Machinery Industry. This standard is drafted by Deyang Large Castings Research Institute. The main drafters of this standard are Jiang Xinliang, Li Wenhua, Pan Yixiang and Jiang Jie.=E/D
When the test does not meet the requirements, the batch of silver pieces shall be checked for residual stress piece by piece or heat treated again according to Article 5.10.1 of this standard. 5.7 Dimensional inspection
Forging dimensions shall be inspected remotely according to the drawings. 5.8 Metallographic inspection
5.8.1Unless otherwise specified, the sulfur print inspection method shall be in accordance with GB4236, and the rating shall be in accordance with JB/ZQ6134. 5.8.2Unless otherwise specified, the sample for measuring grain size shall be taken from the end face of the mechanical properties sample. The product grain size inspection method shall be in accordance with GB6394. 5.9 Retest
5.9.1Retest is allowed when the mechanical properties test results do not meet the specified requirements. However, if the sample fails due to white spots or cracks, retest is not allowed. 5.9.2 If a test result fails due to equipment failure or poor sample preparation, a sample can be taken from the adjacent position of the forging for retesting. 5.9.3 If one of the mechanical properties test does not meet the requirements, two samples should be taken from the adjacent position for retesting, and the test results should meet the requirements.
5.10 Reheat treatment
5.10.1 If the residual stress test result fails, stress removal treatment can be performed again. The stress removal treatment temperature should be 20~50C lower than the final heat treatment tempering temperature. After heat treatment, hardness test and residual stress test should be performed. When the stress removal treatment temperature is within 20℃ lower than the final heat treatment tempering temperature, mechanical property test and residual stress test should be performed piece by piece after heat treatment. When the mechanical property retest of the forging fails, reheat treatment is allowed. After reheat treatment, resampling should be performed for mechanical property test. 5.10.2
The number of reheat treatments shall not exceed 3 for carbon steel and 2 for alloy steel. 6 Acceptance and Certificate of Qualification
The supplier shall provide the necessary convenience to the purchaser's inspector so that the purchaser's inspector can carry out his work. 6.1
6.2. The purchaser has the right to select certain acceptance test items for forgings. If it is found in the acceptance test or in the subsequent processing or test that the forgings do not meet the supplementary technical requirements specified in this standard and the order contract, the purchaser shall promptly notify the supplier and the two parties shall negotiate to resolve the issue. 6.3 The supplier shall provide the purchaser with a certificate of conformity, which shall include the following: a.
Contract number,
Forging drawing number:
Standard number, plating grade and steel type:
Smelting furnace number and roasting method:
Smelting analysis and finished product analysis results:
Main dimensions of steel ingots and actual silver-to-metal ratio of forgings: Actual temperature, holding time and cooling method of each heat treatment; Test results of mechanical properties;
Ultrasonic test report:
Results of other tests and supplementary tests required by the purchaser; Actual dimensions and weight of the delivered forgings;
7 Marking and packaging
The supplier shall mark the contract number, melting furnace number, ingot section number, part number and factory name on the outer peripheral surface of the rim of each forging. The supplier shall pack the products according to the requirements of transportation. 7.2
Additional Notes:
JB/T7028-93
This standard is proposed and managed by Deyang Large Castings and Forgings Research Institute of the Ministry of Machinery Industry. This standard is drafted by Deyang Large Castings Research Institute. The main drafters of this standard are Jiang Xinliang, Li Wenhua, Pan Yixiang and Jiang Jie.
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