JB/T 1582-1996 Ultrasonic flaw detection method for steam turbine impeller forgings
Some standard content:
Machinery Industry Standard of the People's Republic of China
JB/T1582—1996
Ultrasonic Flaw Detection Method for Steam Turbine Impeller Forgings Issued on September 3, 1996
Ministry of Machinery Industry of the People's Republic of China
Implementation on July 1, 1997
JB/T1582—1996
This standard is based on JB/T1266—93 "Technical Conditions for 25~200MW Steam Turbine Discs and Impeller Forgings" and JBT7028-93 "Technical Conditions for 25MW or Less Steam Turbine Discs and Impeller Forgings", and revises JB1582-85 "Ultrasonic Flaw Detection Method for Steam Turbine Impellers".
Since the specific requirements for ultrasonic testing in the two standards JBT1266-93 and B7028-93 are not exactly the same, this standard stipulates a unified evaluation standard as much as possible for easy use. This standard will replace JB1582-85 from the date of implementation. Appendix A of this standard is the appendix of the standard
This standard is proposed and managed by Deyang Large Castings and Forgings Research Institute of the Ministry of Machinery Industry. The drafting unit of this standard: China Second Heavy Machinery Group Corporation. The main drafter of this standard: Fu Tingzhong.
1 Scope
Machinery Industry Standard of the People's Republic of China
Ultrasonic Flaw Detection Method for Steam Turbine Impeller Forgings JB/T1582-1996
This standard specifies various inspection procedures, classification of defect signals, measurement and recording of defects, and flaw detection reports for contact pulse reflection ultrasonic testing of impeller forgings using the direct method. This standard is applicable to ultrasonic flaw detection of various impeller forgings in JB/T1266 and JB/T7028, and can be used as a reference for other wheel forgings. This method should be used as long as the order contract stipulates that forgings are to be ultrasonically inspected according to this method. 2 Reference 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 are subject to revision. Parties using this standard should explore the possibility of using the latest version of the following standards: GB 9445—88
JB/T1266—93
JB4126—85
JB/T 7028—93
ZBY230—84
ZBY231—84
3 General requirements
General rules for technical qualification appraisal of non-destructive testing personnel Technical conditions for 25-200MW steam turbine disks and impeller forgings Manufacture and control of steel test blocks for ultrasonic inspection Technical conditions for steam turbine disks and impeller forgings below 25MW Technical conditions for type A pulse reflection ultrasonic flaw detector Performance test method for probe for ultrasonic flaw detection
3.1 Ultrasonic flaw detection of impeller forgings should be carried out after the final heat treatment, and the material attenuation coefficient should not be greater than 4dBm. 3.2 Impeller forgings should be processed into simple oblate shapes as much as possible to avoid geometric shapes such as cones and grooves that hinder the flaw detection operation. There should be no tool scratches, oxide scale, fine chips left after machining, paint or other foreign matter on the surface. The surface roughness R is not greater than 3.2um3.3 Personnel engaged in ultrasonic flaw detection of impeller forgings should hold a qualification certificate of the corresponding level issued by the relevant department and be able to correctly understand and use this method. The qualification appraisal of flaw detection personnel should comply with the provisions of GB94454 Equipment and accessories
4.1 The ultrasonic flaw detection of impeller forgings adopts A-type pulse reflection ultrasonic flaw detector, and its performance indicators should comply with the provisions of ZBY230.
4.2 The ultrasonic flaw detector used for flaw detection of impeller forgings should have a detection frequency of at least 1 to 5MHz. 4.3 The instrument should provide a linear display of at least 75% of the range from the scanning line to the full screen height, and its vertical linear error should not exceed 5%. 4.4 The combined sensitivity of the instrument should be such that when a Φ2 equivalent defect is found at the maximum sound path of the impeller forging, the residual quantity should not be less than 20B. 4.5 For flaw detection of impeller forgings, a straight probe with a frequency of 2 to 2.5 MHz and a diameter of 20 to 24 mm is generally used. Other probes can be used to evaluate and locate defects, or to detect flaws in special parts. The performance of the probe shall be measured in accordance with the provisions of ZBY231. 4.6 Ordinary engine oil or other coupling agents with good performance can be used as coupling agents, but the same coupling agent shall be used for calibration and testing. Approved by the Ministry of Machinery Industry on September 3, 1996
Implementation on July 1, 1997
5 Inspection Procedures
5.1 General Rules
JB/T 1582—1996
5.1.1 Impeller flaw detection shall be carried out on the end face according to the parts specified in the standard or order agreement. 5.1.2 The scanning speed shall not exceed 150mm/s. 5.1.3 To ensure a comprehensive scan of the impeller forging, the probe shall have at least 15% overlap each time it moves. 5.2 Flaw detection sensitivity
5.2.1 The flaw detection sensitivity used for impeller forgings should be able to effectively detect defects in the impeller being inspected that are equivalent to and greater than Φ2mm flat-bottom holes. During the scanning process, the sensitivity can be appropriately increased to facilitate the detection of defects. However, when defects are found and various measurements are required, the original reference sensitivity should be restored.
5.2.2 The reference height of the flaw detection sensitivity should be selected within the range of 40% to 70% of the scanning line and the full screen height. 5.2.3 When the thickness of the impeller being inspected is equal to or greater than three times the near field of the probe used, the bottom wave method or the test block method can be used to adjust the flaw detection sensitivity; when it is less than three times the near field, the test block method should be used to adjust the flaw detection sensitivity. 5.2.4 Test block adjustment method
5.2.4.1 In principle, the test block adjustment method is carried out using the CS-2 reference test block. Adjust the echo of the flat-bottom hole with a distance equal to or close to the thickness of the impeller being tested and a diameter of 2mm to the reference height selected in 5.2.2. 5.2.4.2 For the shape, size, quantity, material and processing requirements of the CS-2 reference test block, see Appendix A (Appendix to the standard). 5.2.4.3 This standard does not restrict the use of other test blocks with equivalent effects to the CS-2 test block to adjust the flaw detection sensitivity. 5.2.5 Bottom wave adjustment method
5.2.5.1 At the intact part of the impeller forging, adjust the bottom wave to the reference height selected in 5.2.2, and then increase the flaw detector gain dB to the specified value according to the required sensitivity of the Φ2mm flat-bottom hole at the thickness of the impeller being tested. 5.2.5.2 The specified value of the instrument gain can be obtained by formula (1): 4dB = 201g 22T
Wherein: 4dB-the gain decibel number to be increased; T-the thickness of the probed part, mm;
Φ-the diameter of the flat bottom hole, mm (Φ is equal to 2mm here); wavelength, mm;
Yuan-the pi, take 3.14.
5.3 Determination of material attenuation coefficient
5.3.1 The material attenuation coefficient is determined by selecting three locations in the intact part of the impeller and taking the average value. 5.3.2 The material attenuation coefficient (dB/m) of the impeller forging is obtained according to formula (②): a=(B -B,)- 6dB
Material attenuation coefficient, dB/m;
Where: a
(B,-B)--the amplitude difference between the first bottom wave and the second bottom wave, dB; TThe thickness of the workpiece, m.
6 Classification of defect signals
6.1 Dense defect signals
In a cube with a side length of 50mm, the number of defects is five or more, and the equivalent diameter is not less than 1.6mm. 2
6.2 Single scattered defect signals
JB/T1582—1996
The distance between two adjacent defects is greater than 10 times the equivalent diameter of the largest defect, and the equivalent diameter is not less than 2mm.
6.3 Continuous defect signal
A defect signal with an equivalent diameter of not less than 2mm at a certain distance, and a signal amplitude fluctuation range of not more than 2dB within the interval where the probe continuously moves a distance equal to or greater than 30mm.
7 Measurement and recording of defects
7.1 After encountering a defect signal during flaw detection, different methods should be used to measure the defect according to the type of defect signal. 7.2 Measurement of dense defect signals
a) Measure the depth distribution range of the defect according to the position of the defect signal on the scanning line; b) Measure the plane distribution range of the defect according to the moving range of the defect detected by the center of the probe; the equivalent diameter of the defect;
d) The position of the dense defect area on the forging. 7.3 Measurement of single scattered defects
a) Measure the equivalent diameter of the defect using the bottom wave method or the test block comparison method; b) The position of the defect on the forging.
7.4 Measurement of continuous defect signals
a) Measure the indicated length and width of the defect using the half-wave height method; b) The maximum equivalent diameter of the defect;
The location of the defect on the forging.
7.5 When it is necessary to determine the nature of defects, a comprehensive analysis should be conducted based on the defect size (equivalent, length, width, etc.), quantity, shape, orientation distribution, static and dynamic characteristics of the signal, and process factors such as smelting, forging, and heat treatment of the forgings, and opinions on determining the nature of the defects should be put forward. If necessary, other inspection methods should be used for collaborative verification. 7.6 Record all measurement results described in 7.1 to 7.5, as well as other defect signals that the flaw detector believes should be recorded. 8 Flaw Detection Report
8.1 After the flaw detection is completed, a flaw detection report should be written. 8.2 The flaw detection report requires neat handwriting, clear charts, and is completed in the prescribed format. The flaw detection report should include the following contents: a) Forging name, drawing number, material, size diagram, heat treatment status; b) Forging production number, furnace number, card number (workpiece serial number); c) Commissioning unit, commission date, commission number, flaw detection standard, flaw detection conditions, and flaw detection location; ① Defect location, defect depth, equivalent diameter, defect distribution diagram, etc. must be explained; e) Undetected parts and reasons, other situations that the flaw detector considers necessary to explain: \Flaw detection evaluation results;
g) Flaw detection date, signatures of the flaw detector and reviewer. 3
JB/T1582—1996
Appendix A
(Appendix to the standard)
CS-2 reference test block and its technical requirements
A1CS-2 reference test block is a flat test block, which consists of two types of test blocks. One is a large flat bottom block without a flat bottom hole, and the other is a test block with a flat bottom hole with a bottom diameter of 2~8mm.
The total number of test blocks is 36, including 6 large flat-bottom test blocks and 30 flat-bottom hole test blocks. They are made of 45 carbon steel ingots smelted in electric furnaces or open-hearth furnaces, and processed after forging and normalizing (forging ratio is not less than 3). The manufacturing and quality control of CS-2 reference test blocks shall comply with the provisions of B4126. The appearance and dimensions of each part of the test block are shown in Table A1 and Figure A1. Table A1
Aperture d
Range measurement L
Type reference test block dimensions and appearance
Outer diameter D
Height L
≥ 35
≥ 50
≥ 50
≥ 50
≥ 60
Schematic diagram
No.
22100/4
28125/4
29125/6
32150/2
33150/3
34150/4
35150/6
Schematic diagram
Aperture α
Range measurement L
Outer diameter D
Height L
Schematic diagram
Mechanical industry standard
Ultrasonic flaw detection method for turbine impeller forgings JB/T1582—1996| |tt||Published by the Mechanical Science Research Institute
Printed by the Mechanical Science Research Institute
(No. 2, Shouti South Road, Beijing: Postal Code 100044)*
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First Edition in October 1996Www.bzxZ.net
First Printing in October 1996
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Price 5.00 Yuan
No. 96-107
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