JB/T 7178-1993 Technical requirements for 300～600MW steam turbine generator rotor forgings
Some standard content:
Machinery Industry Standard of the People's Republic of China
JB/T 7178-1993
300~600MW Steam Turbogenerator
Technical Conditions for Rotor Forgings
Issued on September 21, 1993
Ministry of Machinery Industry of the People's Republic of China
Implementation on July 1, 1994
Machinery Industry Standard of the People's Republic of China
300~600MW Steam Turbogenerator
Technical Conditions for Rotor Forgings
1 Subject Content and Scope of Application
JB/T 7178-1993
This standard specifies the technical requirements, inspection rules, test methods, certificates and marks of vacuum-treated alloy steel forgings for 300~600MW steam turbine generator rotors.
This standard applies to the ordering, manufacturing and inspection of vacuum-treated alloy steel forgings for 300~600MW steam turbine generator rotors. Cited standards
GB6394
JB1581
JB/ZQ6157
JB/ZQ6101
JB/ZQ6117
JB/ZQ6140
3 Ordering requirements
Chemical analysis methods for steel and alloys
Methods for determining average grain size of metals
Ultrasonic flaw detection methods for turbine and turbo-generator rotor and main shaft forgingsDC impact methodTest methods for determining DC magnetism of materialsMagnetic particle inspection methods for forged steel parts
Test methods for mechanical properties of steel products
Macro-etching test, inspection and evaluation methods for steel products1 The purchaser shall specify the adopted standards, forging grades, steel grades, corresponding technical requirements and inspection items, as well as other additional instructions in the order contract or technical agreement.
Forging grade and steel number shall be marked on the drawing as follows: Steel number
Forging grade × number of this standard
3.2 The purchaser shall provide a rough machining drawing indicating the location of the test specimen for mechanical properties (provide the finishing dimensions if necessary). 4 Technical requirements
4.1 Manufacturing process
4.1.1 Smelting and casting
4.1.1.1 Steel for forgings shall be smelted by ladle refining or electroslag remelting. With the consent of the purchaser, other methods of smelting that ensure quality may also be used. 4.1.1.2 Before or during ingot casting, the molten steel shall be vacuum degassed. During the vacuum treatment process, the ultimate pressure of the vacuum system shall generally be lower than 133Pa.
4.1.2 Forging
4.1.2.1 The upper and lower ends of the steel ingot shall have sufficient removal to ensure that the forging has no shrinkage cavities and unacceptable segregation. 4.1.2.2 Forging should be done on a forging press with sufficient capacity so that the entire cross section of the forging is fully forged. The axial centerline of the forging and the ingot should roughly coincide. The end of the ingot with better quality should be the turbine end of the forging. 4.1.3 Fillet
At each manufacturing stage, the corresponding fillet should be retained at the different step transitions of the forging diameter change. 4.1.4 Heat treatment
The heat treatment after forging is normalizing and tempering.
Approved by the Ministry of Machinery Industry on September 21, 1993
Implementation on July 1, 1994
JB/T7178-1993
Performance heat treatment is quenching and tempering, which should be carried out in a vertical state. The cooling rate of the forging circumference and the entire length should be as consistent as possible.
4.1.4.3 After rough machining and rough bore to the inner and outer diameters specified in the order drawing and leaving a margin of less than 13mm, the forgings shall be subjected to stress relief treatment to ensure that there is no residual stress. 4.1.4.4 For stress relief treatment, the forgings shall be heated to at least 550℃ and not less than 40℃ below the tempering temperature, kept at a sufficient temperature for complete burning, and then cooled to 250℃ at a cooling rate not exceeding 15℃/h and air-cooled out of the furnace. 4.1.5
Machining
The supplier shall punch the center hole of the forging before stress relief treatment. 4.1.5.1
After the performance heat treatment, take the center hole core rod sample. After stress relief treatment, the center hole shall be finely bore and polished or polished by a method that does not cover defects, and the surface roughness R. value is 1.6um. The shipped forgings shall meet the size, tolerance and surface roughness requirements specified in the purchaser's order drawing. Chemical composition
Steel smelting analysis shall comply with the provisions of Table 1.
Forging finished product analysis shall comply with the provisions of Table 1, and the deviation of Table 2 is allowed. Table 1
Chemical composition
25Cr2Ni4MoV
25Cr2Ni4MoV
3.25~4.00
0.20~0.50
0.15-0.35
0.05~0.13
The silicon content shall not exceed 0.10%.
Note: 1) When vacuum carbon deoxidation is used, 1
25Cr2Ni4MoVbzxz.net
The finished product analysis exceeds the specified value,
Note: 1) When vacuum carbon deoxidation is used, the silicon deviation is 0.02%.
The hydrogen content of forgings is not allowed to exceed 1ppm. Mechanical properties
The mechanical properties of forgings shall comply with the provisions of Table 3. P
Table 3 Mechanical properties
Sampling position
Longitudinal, tangential, radial
Longitudinal of center hole core rod
Longitudinal, tangential, radial
Longitudinal of center hole core rod
Longitudinal, tangential, radial
Longitudinal of center hole core rod
1.50-2.00
Analysis and determination, report for reference
Lower limit allowable deviation
590~690
540~690
≥670
660~76 0
610~760
≥690
FATTso
JB/T7178-1993
Continued Table 3
Sampling position
Longitudinal, tangential, radial
Longitudinal of center hole mandrel
Longitudinal, tangential, radial
Longitudinal of center hole mandrel
Note: When other indicators are qualified, the 902 value is allowed to exceed the upper limit by 1
4.3.2 The fluctuation value of the radial tensile strength or yield strength of the forging shaft body is not allowed to exceed 40MPa. 4.4 Residual stress
The residual stress of the forging is not allowed to be greater than 60MPa. Magnetic properties
Magnetic properties shall meet the following requirements:
5.0×10°A/m
15.0×103A/m
50.0×103A/m
120.0×10°A/m
Grain size
B≥1.60 T
The grain size of radial specimen shall not be coarser than grade 5, and grade 4 shall not exceed 5%. The grain size inspection result report of center hole core rod specimen shall be submitted to the purchaser and shall not be used as the basis for acceptance.
4.7 Nondestructive testing
4.7.1 Pickling or magnetic particle testing
4.7.1.1 Forgings shall be free of white spots, cracks, folds and other defects. The buyer reserves the right to use various tests, including pickling and magnetic particle testing. 4.7.1.2 The buyer shall pickle or magnetic particle test one forged R transition zone (one at each end) 200mm outward from both ends of the forged shaft and two bearing parts.
4.7.1.3 Pickling or magnetic particle testing of the bearing parts and the transition zones at both ends of the shaft shall meet the following requirements: On an area of 25cm2 (a rectangle with a maximum side length of 15cm), 5 single defects with a length of 0.5~1mm are allowed to be displayed, or 2 single defects with a length greater than 1~1.5mm are allowed to be displayed. No more than 15 single defects are allowed to be displayed at each bearing part. No more than 20 single defects are allowed to be displayed in each transition zone. When the above provisions are exceeded, the supply and demand parties shall negotiate for settlement.
Ultrasonic flaw detection
Ultrasonic flaw detection is carried out on the outer cylindrical surface of forgings, and the results shall meet the following provisions: a. No defects such as cracks, white spots, shrinkage holes, etc. are allowed; b. No continuous defect signals and floating defect signals with an equivalent diameter equal to or greater than 1.6mm are allowed; c. Defects with an equivalent diameter less than 1.6mm are not counted, and defects with an equivalent diameter equal to or greater than 1.6mm should be recorded and reported to the demander; d. Defects with an equivalent diameter of 1.6~3.5mm are allowed, but the distance between two adjacent defects shall not be less than 10 times the diameter of the larger equivalent defect, and the total number of defects shall not exceed 30; e. In the area with greater stress (within the range of the center hole diameter plus 60mm, and the outer cylindrical groove depth plus 25mm), defects with an equivalent diameter greater than 2mm and dense defect signals greater than or equal to an equivalent diameter of 1.6mm are not allowed; f. Use 2~2.When inspecting at a frequency of 5MHz, the attenuation of the bottom wave caused by the defect shall not exceed 6dB, and the attenuation coefficient of the forging material shall be less than or equal to 4 dB/m.
4.7.3 Center hole
JB/T 71781993
4.7.3.1 When inspecting with a borescope, the inner surface of the center hole shall not have cracks, residual shrinkage holes, pores, slag inclusions, harmful scratches, and defects greater than 3mm in length. The total number of various defects shall not exceed 30. The specific provisions are as follows: a. The number of defects with a length of 0.5~1.5mm gathered on an area of 60cm2 shall not exceed 10; b. The number of scattered defects with a length of 1.5~3mm shall not exceed 10; c. On the entire inner surface of the center hole, the number of point defects with a length of 0.5~1.5mm shall not exceed 25, and defects distributed in a chain shape shall not be allowed.
4.7.3.2 If local trimming or enlargement of the center hole is required to remove larger defects, the purchaser's consent must be obtained in advance. 4.7.3.3 If the purchaser requires magnetic particle inspection of the center hole, it can be carried out by the purchaser. In the event of objections during the magnetic particle inspection, the supply and demand parties shall negotiate to resolve the issue. 4.8 Dimensions, tolerances, and surface roughness
4.8.1 Forging processing shall comply with the dimensions, tolerances, and surface roughness requirements specified in the purchaser's order drawings. 4.8.2 The roundness error of the center hole is not allowed to exceed 0.3mm. The surface roughness R value of the center hole is 1.6um. The coaxiality error between the center hole and the outer circle shall not exceed 1.0mm. The straightness tolerance value of the center hole axis is within a cylinder with a diameter of less than 6mm. 5 Inspection rules and test methods
5.1 Chemical composition analysis
5.1.1 Melting analysis
5.1.1.1 The supplier shall take samples for melting analysis when casting each furnace of molten steel ingots and report the analysis results. The weight analysis results shall also be reported when multiple furnaces are cast.
5.1.1.2 If the sample is not suitable for melting analysis, the supplier may take a substitute sample from a suitable position near the surface of the ingot or forging, and inform the buyer of the analysis results and sampling location.
5.1.2 Finished product analysis
The supplier shall conduct finished product analysis for each forging. The sample is taken from the longitudinal sample of the mechanical properties of the forging, and can also be taken from the radial performance sample. 5.1.3 Gas analysis
Take radial samples to analyze the hydrogen content.
5.1.4 Analysis method
Perform in accordance with GB223 and related methods.
5.2 Mechanical properties test
5.2.1 After heat treatment or stress relief treatment, the test is carried out according to the JB/ZQ6117 method. 5.2.2 Impact test specimens are in accordance with the provisions of the Charpy V-notch test specimens in JB/ZQ6117. The notch direction of the radial impact test specimen should be tangential. 5.2.3 Sampling position and number of test specimens shall comply with the following provisions if there are no special requirements: 5.2.3.1 Longitudinal test specimens: The supplier and the buyer shall take 2 tensile test specimens and 2 impact test specimens at both ends of the forging. Forgings with center holes shall be sampled at 1/2 of the wall thickness, and forgings without center holes shall be sampled at 1/3 of the radius from the surface. 5.2.3.2 Tangential test specimens: Tangential test specimens shall be cut from test rings cut as close as possible to 1/3 of the radius of the shaft surface at both ends of the shaft body. The supplier shall cut the ring at the end of the shaft body corresponding to the poorer quality of the ingot, and the buyer shall cut the ring at the other end. Take 4 tensile specimens and 2 impact specimens from each end of the test ring, and cut them at the same relative position of the diameter of the test ring. 5.2.3.3 Radial specimens: 4 radial material rods should be set on a baseline parallel to the axis in the radial direction. The distance from both ends of the shaft body shall not be less than 200mm. The hole diameter and hole depth after setting shall comply with the requirements of the order drawing. a. Take 2 tensile specimens (1 each) from the bottom of the groove of the two set material rods, and take 1 room temperature impact specimen and 1 specimen for measuring the brittle transition temperature from the outer end close to the tensile specimen. b. The other two set material rods should adopt the opposite method, that is, take 2 tensile specimens (1 each) from the outer end, and take 1 room temperature impact specimen and 1 specimen for measuring the brittle transition temperature from the bottom of the groove. 4
JB/T7178—1993
c. The impact test specimens for determining the brittle transition temperature shall be carried out at the temperature specified in Table 3, and both specimens shall show at least 50% of the plastic fracture.
d. The radial tensile test specimens may be specimens with a diameter of not less than 5mm, and the radial impact test specimens shall be 10mm×10mm×55mm (V-notch) specimens.
5.2.3.4 Center hole test specimens: One tensile test specimen shall be taken from the mandrels at both ends and the middle of the shaft body, and at least four impact test specimens shall be taken from the mandrel in the middle of the shaft body to determine the value of the brittle transition temperature. 5.3 Residual stress test
5.3.1 The residual stress shall be determined by the ring cutting method or the ring core resistance strain method. 5.3.2 The supplier and the buyer shall take a 25mm×25mm ring at one end of the forged shaft respectively, and calculate the residual stress by measuring the average deformation of the ring before and after cutting. The calculation formula is: G=E8/D
Where: α is the residual stress, MPa;
3 is the algebraic value of the diameter increment, mm;
D is the outer diameter of the ring before cutting, mm;
E is the elastic modulus of the material, MPa.
5.3.3 If the residual stress is unqualified, the forging can be supplemented with tempering. The residual stress inspection results after supplementary tempering shall comply with the provisions of Article 4.4 of this standard.
5.4 Magnetic property measurement
The buyer shall measure the magnetic properties of the forging. Unless otherwise specified by the buyer, it shall be carried out according to the JB/ZQ6157 method. Take a magnetic property sample on the tangential test ring of the shaft, and its size shall be determined according to the equipment of each factory. 5.5 Grain size determination
On the shaft radial specimen near the bottom of the groove and the end face of the center hole mandrel specimen, according to the GB6394 method. 5.6 Nondestructive testing
5.6.1 Pickling or magnetic particle inspection
5.6.1.1 The purchaser shall order the parts specified in the drawing, and pickle them after semi-finishing with a single side margin of 2mm and a surface roughness R of 0.8um.
5.6.1.2 Pickling shall be carried out according to the JB/ZQ6140 method. 5.6.1.3 If the purchaser requires magnetic particle inspection, it shall be carried out according to the JB/ZQ6101 method. 5.6.2 Ultrasonic flaw detection inspection
After rough machining and performance heat treatment, it is carried out according to the JB1581 method, but the "defect signal with an equivalent diameter of not less than 2mm" in the definition of defect signals in this method is adjusted to "defect signal with an equivalent diameter of not less than 1.6mm". 5.6.3 Center hole inspection
After the surface roughness R value of the center hole reaches 1.6μm, use a bore peep tester or a magnetic particle combined with a bore peep tester to inspect the entire inner hole surface. The magnetic particle inspection is carried out according to the JB/ZQ6101 method. 5.7 Retest and re-heat treatment
5.7.1 Retest is allowed if the mechanical property test results do not meet the requirements. Retest is not allowed when the test results are unqualified due to cracks or white spots. 5.7.2 When the test results of any sample are unqualified, select two samples at adjacent positions for retest, and the test results of the two samples must meet the requirements.
If the retest result of any mechanical property test is still unqualified, the supplier may reheat treat the forging. Without the consent of the purchaser, the number of reheat treatments is not allowed to exceed three times. Reheat treated forgings shall be inspected in accordance with Article 5.2 of this standard. 5.7.4 When reheat treating forgings, the remaining center hole core rod shall be put back into the center hole. 5
Acceptance and Certificate of Qualification
JB/T7178-1993
6.1 The supplier shall provide the purchaser's inspector with necessary convenient conditions so that the purchaser's inspector can carry out his work. The purchaser's inspector shall not cause unnecessary obstruction to the supplier's production. Unless otherwise specified, all inspections shall be carried out at the supplier. 6.2 Forgings shall be accepted by the supplier's quality inspection department in accordance with this standard, and the purchaser may re-inspect in accordance with this standard. 6.3 The supplier shall provide the purchaser with a certificate of conformity, including the following: a. Order contract number; b. Forging drawing number, steel number: c. Standard number and forging grade number; d. Melting furnace number, forging card number; e. Melting analysis and finished product analysis results; f. Mechanical properties test results; g. Non-destructive test results, including defect distribution sketch; h. Final austenitizing temperature and tempering temperature and cooling method; i. Other required test results. 6.4 After the supplier's acceptance of the forging, if the purchaser re-inspects and during the processing, any unacceptable defects are found, the purchaser shall promptly notify the supplier and the two parties shall negotiate to resolve.
7 Marking and Packaging
7.1 The supplier shall mark the supplier’s factory name or logo, contract number, smelting furnace number and forging card number on the end face of each forging that is equivalent to the lower end face of the steel ingot. 7.2
The center hole of each forging should be coated with an antiseptic and plugged with a wooden plug to prevent damage or corrosion during transportation and storage. Additional remarks:
This standard was proposed and managed by the Deyang Large Castings and Forgings Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Deyang Large Castings and Forgings Research Institute. The main drafters of this standard were Zeng Xiushi, Guo Chenghai, Xuan Pinfan, and Ma Feiliang. 6
People's Republic of China
Mechanical Industry Standard
300~600MW Steam Turbine Generator
Technical Conditions for Rotor Forgings
JB/T71781993
Published and issued by the China Academy of Mechanical Science
Printed by the China Academy of Mechanical Science
(No. 2 Shouti South Road, Beijing
Postal Code 100044)
Sheet 5/8
Format 880×1230
Word Count 12,000
First Edition in May 1994
First Printing in May 1994
Print Quantity 1-500
Price 6.00 Yuan
Mechanical Industry Standard Service Network: http://www.JB.ac.cn66_8
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