Some standard content:
ICS 77.040.20
National Standard of the People's Republic of China
GB/T8651--2002
Replaces GB/T8651—1988
Metal plates---Flaw detection method by the ultrasonic plate wave
Metal plates---Flaw detection method by the ultrasonic plate waveIssued on 2002-07-15
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
Implementation on 2002-12-01
GB/T 8651--2002
This standard replaces GB/T8651-1988 "Metal plates---Flaw detection method by the ultrasonic plate wave". This revision of this standard has modified the following major technical contents: In the definition of plate wave, the original description of dispersion curve has been modified, and the types of specimens have been added according to the different types of defects actually detected, making the selection of specimens more flexible; the provisions of the original standard that "the specimen allows the supply and demand parties to reach an agreement, and other forms of reliable specimens can be determined according to requirements" have been deleted - the dispersion curves of plate waves of several commonly used materials have been added. Appendix A, Appendix B, Appendix C, Appendix D, Appendix E, Appendix F, Appendix G, Appendix H, Appendix 1, Appendix J, Appendix K, Appendix I, and Appendix M of this standard are informative appendices.
This standard was proposed by the former State Metallurgical Industry Bureau. This standard is under the jurisdiction of the National Steel Standardization Technical Committee. The drafting units of this standard are: General Iron and Steel Research Institute, Metallurgical Industry Information Standards Research Institute. The main drafters of this standard are: Fei Huiming, Zhang Guangchun, Xu Kebei, Zhang Jianwei, and Huang Ying. This standard was first published in 1988.
1 Scope
Metallic sheet ultrasonic plate wave flaw detection method
GB/T 8651—2002
This standard specifies the general requirements, flaw detection equipment, comparison specimens, selection of plate wave mode, flaw detection method and defect assessment of metallic sheet ultrasonic plate wave flaw detection method.
This standard is applicable to ultrasonic plate wave flaw detection of metallic sheet such as container steel, stainless steel, high temperature alloy, etc. whose thickness is not more than 5 times of the surface wave wavelength of the inspected sheet. However, it must be confirmed that the excited sound wave is indeed a plate wave and can be used for flaw detection with sufficient flaw detection sensitivity. 2 Normative references
The clauses in the following documents become the clauses of this standard through reference in this standard. For dated references, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties to an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For undated references, the latest versions are applicable to this standard. GB/T12604.1 Nondestructive testing terminology Ultrasonic testing JB/T10061 General technical conditions for type A pulse reflection ultrasonic flaw detector 3 Terms and definitions
The terms and definitions established in GB/T12604.1 and the following terms and definitions apply to this standard. 3.1
i wave plate wave
Plate wave refers to the acoustic traveling wave propagating in the plate when the cross-sectional thickness of the sound-conducting plate-shaped object is of the same order of magnitude as the wavelength. It includes Lamb wave and SH wave. Lamb wave is a composite of longitudinal wave and vertically polarized shear wave, while SH wave is a horizontally polarized shear wave. Each plate wave has its own frequency equation and dispersion curves drawn in turn, that is, the relationship curve between phase velocity and group velocity to the product of frequency and plate thickness and the particle displacement curve.
Dispersion
Also known as dispersion, it refers to the phenomenon that the speed of sound changes with frequency. 3.3
Mode mode
indicates the relationship between the direction of particle displacement and the direction of propagation. In plate waves, the mode of the wave indicates how the displacement of the particle changes with respect to the center of the plate during the sound propagation process.
4 General requirements
4.1 Plate wave flaw detection can be performed with piezoelectric transducers or electromagnetic acoustic transducers. Regardless of the transducer used, it should be ensured that the center frequency of the flaw detection sensitivity transducer should match the frequency of the transmitting and receiving units of the detection equipment. The bandwidth of the transmitting and receiving units of the detection equipment should be as narrow as possible.
4.2 The surface of the plate to be detected should be flat, smooth, and of uniform thickness, and should not have droplets, oil, corrosion, or other contaminants. 4.3 The metallographic structure of the plate to be detected should not produce disturbing echoes that affect the flaw detection during flaw detection. 4.4 The flaw detection site should avoid strong light, strong magnetic field, strong vibration, corrosive gas, severe dust and other factors that affect the stability of ultrasonic flaw detectors or reliable observation of flaw detectors.
4.5 Personnel engaged in plate flaw detection should hold a professional ultrasonic flaw detection qualification certificate of level 1 or above recognized by the authority, and have sufficient ultrasonic flaw detection knowledge, especially the basic knowledge and skills of plate wave flaw detection. Those who issue flaw detection reports should obtain a professional ultrasonic flaw detection qualification certificate of level [level] or [level] or above recognized by the authority. 5 Flaw detection equipment
5.1 The ultrasonic flaw detector used for plate flaw detection should have a sufficiently high transmission power and a sufficiently wide transmission pulse width. 5.2 The frequency band of the excitation pulse of the transmitting unit should be as narrow as possible to avoid exciting unnecessary plate wave modes. Pulse modulated sine wave transmitting units should be used as much as possible.
5.3 The piezoelectric probe chip should be long enough and the incident angle should be as close as possible to reduce the excitation of the unwanted plate wave mode, and the probe must actually measure the frequency of the emitted sound wave on the standard test block to meet the requirements in 4.1. 5.4 Other performances of the flaw detector should meet the requirements of B/T10061. 5.5 Other flaw detection equipment such as transmission mechanism should ensure the reliability and repeatability of the flaw detection results. 6 Comparison sample
6.1 The comparison sample is used to adjust the sensitivity of the flaw detection system. 6.2 The comparison sample should have the same thickness, acoustic properties and surface state as the plate to be detected and there should be no natural macroscopic defects inside that affect the flaw detection. 6.3 The comparison sample should be cut from the finished plate, with its long side perpendicular to the rolling direction, the end face straight, and the thickness tolerance less than 2% of the plate thickness.
6.4 The artificial flaws of the comparison sample can be made by drilling or notching. The size and shape of the comparison sample are shown in Figure 1 (a), (b), (c), (d). The through hole diameter in Figure 1(a) shall comply with the provisions of Table 1. 6.5 The type of comparison specimen shall be determined by negotiation between the supplier and the buyer. Table 1 Through hole type comparison specimen Through hole diameter
Plate thickness d
Through hole diameter
0. 5~1. 0
>1. 0～2.0
≥2.0～4.0
>4. 0～8. 0
>8.0～10
Unit: mm
≥500
a) Through hole type comparison specimen
(b) Wire cutting type comparison specimen
≥500
(c) Artificial layering (embedded mica) type comparison speciment
(d) Flat bottom groove type comparison specimen
1～~2
Note 1: The machining dimension tolerance of each drill hole or groove in all the above comparison specimens shall not be greater than 10%; Note 2: Machining requirements for comparison specimens: There shall be no burrs, and the bottom of the groove shall not have obvious chamfers; Note 3: The dimensions in the figure are all in mm,
Note 4: The distance between the artificial flaw and the board edge can be adjusted as needed. Figure 1 Schematic diagram of plate wave flaw detection specimen
GB/T 8651--2002
GB/T8651--2002
7 Selection of plate wave mode
7.1 The method of selecting the plate wave mode during flaw detection is to find the phase velocity of the required mode under the given plate thickness and selected working frequency based on the frequency equation of the plate wave or the dispersion curve drawn by it. For the organic glass wedge-type piezoelectric probe, the Lamb wave can be calculated according to the following formula for the incident angle α.
α arcsin
Where:
Cp---Phase velocity of the excited Lamb wave mode; Ct.---Longitudinal wave velocity of organic glass.
For several commonly used plate wave dispersion curves, see Appendix B, Appendix C, Appendix D, Appendix E, Appendix F, Appendix G, Appendix H, Appendix I, Appendix J, Appendix K, Appendix L, and Appendix M.
7.2 No matter which method is used to select the plate wave mode, the consistency of the detection sensitivity of the supplier and the buyer must be ensured, and various defects must not be missed. If necessary, two or more plate wave modes can be used for flaw detection. 7.3 In order to reduce the mixed phenomenon on the signal display caused by dispersion, when selecting the plate wave mode and frequency, the rate of change of the group velocity to the frequency-thickness product should be as small as possible. The plate wave mode selected by the supplier and the buyer must be consistent. 8 Flaw detection method and defect assessment
8.1 Flaw detection method
8.1.1 According to the artificial flaws agreed upon in the contract (agreement) between the supply and demand parties, adjust the initial sensitivity of the flaw detection, so that the echo height of all artificial flaws is adjusted to not less than 80% of the full scale of the instrument's fluorescent screen, and the instrument has sufficient sensitivity margin. The sensitivity should be increased by at least 6dB during scanning. In order to improve the efficiency of flaw detection, the distance from the probe to the artificial flaw should be as large as possible. 8.1.2 The detection direction should be perpendicular to the rolling direction of the plate. If necessary, it should be detected again along the rolling direction. 8.1.3 When using a piezoelectric probe, ensure that the acoustic coupling is stable. 8.1.4 During the flaw detection process, ensure that the blind area of the plate edge is not greater than 50mm. 8.2 Defect evaluation
8.2.1 When an echo signal appears between the initial wave and the plate edge reflection wave on the flaw detector's fluorescent screen or the position of the plate edge reflection wave is abnormal, it should be regarded as a defect signal after eliminating factors such as interference and changes in the scanning distance, and the size and echo height of the defect should be further evaluated from other directions. For strip defects, the 6dB attenuation method can be used to determine its indication length. 8.2.2 The location of the defect can be determined by the drop method or the test block comparison method. 8.2.3 The location and size of the detected defect can be verified by ultrasonic thickness measurement or other appropriate methods. 9 Flaw detection records and reports
9.1 The flaw detection record should at least include the following main contents: a) test items, plate number, plate specification, flaw detection standard number; b) flaw detection method (or process specification), flaw detection instrument, working frequency, probe frequency, probe size, probe angle, plate wave mode; comparison sample thickness, comparison sample size of artificial flaws used to calibrate sensitivity, detection distance: c)
flaw detection initial sensitivity, defect indication position and indication length and echo height and other detection results; flaw detection date, flaw detection personnel signature, etc. e)
9.2 The flaw detection report should include the appropriate content in the flaw detection record and the signature of the person issuing the report. Frequency equation of symmetric type (s type):
Frequency equation of asymmetric type (a type):
In the formula: α/C-2
w2/C22
w=2-element f
(Informative Appendix)
Frequency equation of plate wave under free boundary conditions tg(dp/2)
tg(dα/2)
tg(dp/2)
tg(dα/2)
C. Longitudinal wave velocity in the material, in seconds per meter (m/s); C.
Shear wave velocity in the material, in seconds per meter (m/s); -Lamb wave phase velocity, in seconds per meter (m/s); Plate thickness, in meters (m);
Lamb wave excitation frequency, in Hertz (Hz). 4a2
(2 - pe)2
(e2 p2)2
GB/T8651—2002
GB/T8651—2002
Appendix B
(Informative Appendix)
Plate wave dispersion curve of 406 high strength steel plate
In 406 steel: longitudinal wave velocity Ct=5920m/s10000
Shear wave velocity C=3200m/s
Frequency×thickness/(MHz·mm)
Figure B1 Lamb wave phase velocity curve of 406 steel plate Line
Frequency×thickness/(MHzmm）
Figure B2406 Lamb wave group velocity curve for steel plate
Symmetrical type n=0,2,4,6·…·
Asymmetric type n-1,3,5,7…
Frequency×thickness/(MHzmm）
Figure B3406 SH wave phase velocity curve for steel
Frequency×thickness/(MHzmm）
Figure B4406 SH wave group velocity curve for steel plate
GB/T 8651—2002
GB/T 8651-—2002
Appendix C
(Informative Appendix)
Plate wave dispersion curve of low carbon steel plate
Low carbon steel: longitudinal wave velocity CL-5954m/s10000
(/a)4g
Shear wave velocity C,=3229m/s
Frequency×thickness/(MHz?mm)
Lamb wave phase velocity curve of low carbon steel plate
Frequency×thickness/(MHz-mm）
Figure C2 Lamb wave group velocity curve of low carbon steel plate 10
Appendix D
(Informative Appendix)
1Cr13 material plate wave dispersion curve
In 1Cr13 material: longitudinal wave velocity Cl=6220m/s12000
(s/)/提
Shear wave velocity C-3220m/s
Frequency×thickness/(MHzmm）
Figure D1 1Cr13 material Lamb Wave phase velocity curve 6000
Frequency×thickness/(MHzmm）
Figure D21Cr13 material Lamb wave group velocity curve 10
GB/T 8651-2002
GB/T 8651—2002
Appendix E
(Informative Appendix)
1 Plate wave dispersion curve of Cr18Ni9Ti material
1 In Cr18Ni9Ti material: longitudinal wave velocity CL = 5895m/s12000
Shear wave velocity C, = 3098m/s
Frequency×thickness/(MHzmm）
Figure E11 Lamb wave phase velocity curve of Cr18Ni9Ti material 2
Frequency×thickness/MHz·mm）
Figure E21 Lamb wave group velocity curve of Cr18Ni9Ti material 10
The shear wave velocity in the material, in m/s; -Lamb wave phase velocity, in m/s; plate thickness, in m;
Lamb wave excitation frequency, in Hz. 4a2
(2 - pe)2
(e2 p2)2
GB/T8651—2002
GB/T8651—2002
Appendix B
(Informative Appendix)
Plate wave dispersion curve of 406 high-strength steel plate
In 406 steel: longitudinal wave velocity Ct=5920m/s10000
Transverse wave velocity C=3200m/s
Frequency×thickness/(MHz·mm)
Figure B1 Lamb wave phase velocity curve of 406 steel plate Line
Frequency×thickness/(MHzmm）
Figure B2406 Lamb wave group velocity curve for steel plate
Symmetrical type n=0,2,4,6·…·
Asymmetric type n-1,3,5,7…
Frequency×thickness/(MHzmm）
Figure B3406 SH wave phase velocity curve for steel
Frequency×thickness/(MHzmm）
Figure B4406 SH wave group velocity curve for steel plate
GB/T 8651—2002
GB/T 8651-—2002
Appendix C
(Informative Appendix)
Plate wave dispersion curve of low carbon steel plate
Low carbon steel: longitudinal wave velocity CL-5954m/s10000
(/a)4g
Shear wave velocity C,=3229m/s
Frequency×thickness/(MHz?mm)
Lamb wave phase velocity curve of low carbon steel plate
Frequency×thickness/(MHz-mm）
Figure C2 Lamb wave group velocity curve of low carbon steel plate 10
Appendix D
(Informative Appendix)
1Cr13 material plate wave dispersion curve
In 1Cr13 material: longitudinal wave velocity Cl=6220m/s12000
(s/)/提
Shear wave velocity C-3220m/s
Frequency×thickness/(MHzmm）
Figure D1 1Cr13 material Lamb Wave phase velocity curve 6000
Frequency×thickness/(MHzmm）
Figure D21Cr13 material Lamb wave group velocity curve 10
GB/T 8651-2002
GB/T 8651—2002
Appendix E
(Informative Appendix)www.bzxz.net
1 Plate wave dispersion curve of Cr18Ni9Ti material
1 In Cr18Ni9Ti material: longitudinal wave velocity CL = 5895m/s12000
Shear wave velocity C, = 3098m/s
Frequency×thickness/(MHzmm）
Figure E11 Lamb wave phase velocity curve of Cr18Ni9Ti material 2
Frequency×thickness/MHz·mm）
Figure E21 Lamb wave group velocity curve of Cr18Ni9Ti material 10
The shear wave velocity in the material, in m/s; -Lamb wave phase velocity, in m/s; plate thickness, in m;
Lamb wave excitation frequency, in Hz. 4a2
(2 - pe)2
(e2 p2)2
GB/T8651—2002
GB/T8651—2002
Appendix B
(Informative Appendix)
Plate wave dispersion curve of 406 high-strength steel plate
In 406 steel: longitudinal wave velocity Ct=5920m/s10000
Transverse wave velocity C=3200m/s
Frequency×thickness/(MHz·mm)
Figure B1 Lamb wave phase velocity curve of 406 steel plate Line
Frequency×thickness/(MHzmm）
Figure B2406 Lamb wave group velocity curve for steel plate
Symmetrical type n=0,2,4,6·…·
Asymmetric type n-1,3,5,7…
Frequency×thickness/(MHzmm）
Figure B3406 SH wave phase velocity curve for steel
Frequency×thickness/(MHzmm）
Figure B4406 SH wave group velocity curve for steel plate
GB/T 8651—2002
GB/T 8651-—2002
Appendix C
(Informative Appendix)
Plate wave dispersion curve of low carbon steel plate
Low carbon steel: longitudinal wave velocity CL-5954m/s10000
(/a)4g
Shear wave velocity C,=3229m/s
Frequency×thickness/(MHz?mm)
Lamb wave phase velocity curve of low carbon steel plate
Frequency×thickness/(MHz-mm）
Figure C2 Lamb wave group velocity curve of low carbon steel plate 10
Appendix D
(Informative Appendix)
1Cr13 material plate wave dispersion curve
In 1Cr13 material: longitudinal wave velocity Cl=6220m/s12000
(s/)/提
Shear wave velocity C-3220m/s
Frequency×thickness/(MHzmm）
Figure D1 1Cr13 material Lamb Wave phase velocity curve 6000
Frequency×thickness/(MHzmm）
Figure D21Cr13 material Lamb wave group velocity curve 10
GB/T 8651-2002
GB/T 8651—2002
Appendix E
(Informative Appendix)
1 Plate wave dispersion curve of Cr18Ni9Ti material
1 In Cr18Ni9Ti material: longitudinal wave velocity CL = 5895m/s12000
Shear wave velocity C, = 3098m/s
Frequency×thickness/(MHzmm）
Figure E11 Lamb wave phase velocity curve of Cr18Ni9Ti material 2
Frequency×thickness/MHz·mm）
Figure E21 Lamb wave group velocity curve of Cr18Ni9Ti material 10
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