Some standard content:
National Standard of the People's Republic of China
Ultrasonic angle beam examination by the contact method
1 Subject content and scope of application
UDC 620. 178. 16
GB 11343—89
This standard specifies the inspection technology and calibration of contact A-type ultrasonic oblique longitudinal wave, transverse wave, Rayleigh wave and Lamb wave, and makes appropriate provisions for system equipment. This standard applies to the oblique beam flaw detection in which the ultrasonic probe is in direct contact with the object to be inspected in conventional ultrasonic flaw detection. 2 Reference standards
ZBY230--84 General technical conditions for A-type pulse reflection ultrasonic flaw detector ZBY231--84 Performance test method for ultrasonic flaw detection probe ZBY232--84 Technical conditions for No. 1 standard test block for ultrasonic flaw detection ZBJ04001--87 Working performance test method for A-type pulse reflection ultrasonic flaw detection system 3 General provisions
3.1 The ultrasonic oblique flaw detection method should select the wave direction and vibration mode according to the geometric shape of the material and the possible location, shape, size, direction and reflectivity of the defects.
3.2 The operator must hold a qualification certificate issued by the relevant national competent authorities and suitable for his work. 3.3 If quantitative ultrasonic oblique flaw detection is required, the vertical linearity and horizontal linearity applicable to the instrument should be calibrated according to the ZBY230 standard or other methods agreed by the inspection agency and the unit requiring the inspection. 3.4 The flaw detection system should be calibrated according to the ZBJ04001 standard before inspection. 3.5 The inspection results shall be evaluated according to the technical conditions for acceptance of the inspected products or the specified standards. 4 Inspection system
4.1 Instrument
The ultrasonic flaw detector shall comply with the ZBY230 standard. If there are special requirements for the flaw detector, other methods agreed upon by the product inspection unit and the inspection unit may be used for calibration.
4.2 Probe
The oblique shear wave detection probe shall comply with the ZBY231 standard. The probe shall be equipped with an inclined wedge that can transmit ultrasonic waves to the inspected object at the required angle and wave shape. Other probes may also refer to the ZBY231 standard. 4.3 Coupling agent
4.3.1 Sufficient coupling agent shall be applied between the probe oblique wedge and the inspection surface of the inspected object to ensure good acoustic coupling during the inspection. 4.3.2 The coupling agent is usually a liquid or paste. Typical coupling agents are engine oil, water, glycerin, paste, water-soluble oil and grease. Rust inhibitors or wetting agents may be added to the coupling agent. The selected coupling agent should be harmless to the product or process. Approved by the State Administration of Technical Supervision on May 8, 1989 112
Implementation on January 1, 1990
GB11343-89
4.3.3 Surfaces that are not suitable for flaw detection must be processed by appropriate methods. After being suitable for flaw detection, the appropriate coupling agent should be selected according to the surface roughness of the material to be inspected and the orientation of the detection position. Generally speaking, a higher viscosity coupling agent is required when inspecting materials with rough or inclined surfaces. The coupling agent used for inspection must be the same as that used for calibration. 4.4 Test blocks for calibration
4.4.1 Test blocks with artificial reflectors of known size can be used as calibration test blocks. 4.4.2 The shape of the artificial reflector can be a horizontal hole, a groove or a flat bottom hole. 4.4.3 The test block should be made of a material with the same sound velocity, attenuation, curvature and surface roughness as the object to be inspected. If these conditions cannot be met, appropriate corrections should be made to the effects caused during product inspection; the correction methods for different specific products should be included in the product acceptance standards. 4.4.4 During inspection, calibration test blocks should be selected according to the corresponding standards and relevant regulations, and calibration test blocks should not be mixed. 4.5 The surface temperature difference of the inspected object during inspection and calibration should be within ±14°C to avoid large attenuation and sound velocity differences in the wedge material.
5 Oblique shear wave inspection technology and calibration
5.1 Inspection technology
5.1.1 The most commonly used oblique shear wave refraction angle should be within the range of 40°~75°. When the refraction angle is 80°~85°, Rayleigh waves are easily generated on the material surface at the same time. Oblique waves within this angle range should be limited. 5.1.2 Oblique shear wave inspection usually adopts a single probe type. Dual probe types can also be used. When flaw detection, the possible defect types and defect generation directions should be fully estimated so that the ultrasonic beam can be directed to the defect to produce the most ideal reflection. If the direction of the defect is arbitrary, it is often necessary to check with multiple sound beam directions or rotate the sound beam. 5.2 Calibration
5.2.1 Oblique shear wave flaw detection Since the detection objects are different, the frequencies and probe types used and the test blocks they use are also different. If the object to be inspected has an appropriate geometric shape, the object to be inspected itself can provide a more reliable calibration. 5.2.2 The frequency of use, probe and test block type, etc. should be stated in the flaw detection procedures for specific products. When necessary, a distance-amplitude calibration curve should be made. Www.bzxZ.net
5.2.3 Within the commonly used sound range, the distance characteristic curves of oblique probes are often different, so when making the calibration curve, the probe used for actual flaw detection must be used.
6 Oblique longitudinal wave inspection technology and calibration
6.1 Inspection technology
6.1.1 The refraction angle of the oblique longitudinal wave is 1°~~40° (at this time, there is also a very weak oblique shear wave). 6.1.2 When inspecting with oblique longitudinal waves, shear waves always exist at the same time. Therefore, care should be taken when calibrating the distance scale to avoid erroneously citing the shear wave signal with a larger travel time for calibration.
6.1.3 Probes generally used in the oblique longitudinal wave range can be divided into three groups: single crystal probes, dual crystal probes with parallel sound beams, and dual crystal probes with crossed sound beams.
6.1.3.1 Single crystal probes
a. Single crystal probes are rarely used in the oblique longitudinal wave range. Generally, single crystal probes can be used to detect defects at the ends of shafts by direct reflection or angular reflection.
When the angle of the main reflection surface of the expected defect is known, the angle of the inspection sound beam should be perpendicular to this reflection surface. In areas where defects may exist, the material should be scanned under the condition that the sound beam and the main plane of the defect are perpendicular to each other. b. Under special circumstances, oblique longitudinal waves can be used for austenitic stainless steel welds. 6.1.3.2 Parallel beam dual crystal probe
When the sound path of the reflector is short, in order to avoid clutter in the wedge, separate transmitting and receiving probes or dual crystal probes can be used. In the dual crystal probe, the transmitting crystal and its wedge are separated from the receiving crystal and its wedge by sound insulation material to prevent crosstalk. The transmitting sound beam and the receiving sound beam are basically parallel.
6.1.3.3 Cross-beam oblique longitudinal wave dual crystal probe GB 11343—89
This probe makes the sound beam cross directly below the surface to be inspected. Although it can improve the near-surface resolution, the detection depth is limited by the crystal size and the sound beam angle. This probe is mainly used for thickness measurement or inspection of reflectors parallel to the detection surface, such as defects such as interlayers. Special care should be taken in the calibration of the detection depth and when the instrument works in a one-receive-one-transmit mode. 6.2 Calibration
6.2.1 Different test blocks should be used for oblique longitudinal wave flaw detection according to different detection objects, operating frequencies and probe types. If the object to be inspected has an appropriate geometric shape, the object to be inspected itself can provide more reliable calibration. 6.2.2 In the flaw detection regulations for specific products, the operating frequency, probe and test block type, etc. should be stated. A distance-amplitude calibration line should be made when necessary.
6.2.3 Within the commonly used sound range, the distance characteristic curves of oblique probes are often different. Therefore, when making the calibration curve, the probe used for actual flaw detection must be used.
7 Rayleigh wave inspection technology and calibration
7.1 Inspection technology
7.1.1 On the inspection surface, Rayleigh waves propagate at 90° to the normal of the inspection surface. In materials with a thickness greater than two wavelengths, the energy of Rayleigh waves penetrates approximately to a depth of one wavelength. Since the energy is distributed in an exponential form, half of the energy is concentrated in the surface layer of one quarter of the penetration (wavelength) depth.
7.1.2 When Rayleigh waves encounter shuttle edges during propagation, if the edge curvature radius R is greater than 5 times the wavelength, the Rayleigh waves can pass completely without hindrance. When R gradually becomes smaller, part of the Rayleigh wave energy is reflected by the edge. When R≤ (wavelength), the reflected energy is maximum. Therefore, Rayleigh waves are often used to detect surface and near-surface defects in ultrasonic flaw detection. 7.1.3 Since the penetration depth changes when the wavelength changes, the depth of cracks perpendicular to the propagation direction of the Rayleigh wave can be estimated by changing the frequency of the Rayleigh waves.
7.2 Calibration
7.2.1 Rayleigh waves require sudden changes in surface geometry (i.e. corners, square grooves, etc.) as a reference for distance calibration. The scanning line on the fluorescent screen should be calibrated according to the distance from the probe to the reflector on the comparison test block. 7.2.2 In amplitude calibration, it should be considered that the penetration depth of Rayleigh waves is related to the frequency. Therefore, in the relevant requirements, the maximum depth of burial of defects allowed by the reference reflector used for calibration should be stated. The inspection frequency is calculated according to the following formula: f-VR4d
Where: f---the operating frequency, Hz;
Vr---the speed of Rayleigh waves in the material, mm/s; d--the burial depth of the reference reflector, mm.
8 Lamb wave inspection technology and calibration
8.1 Inspection technology
8.1.1 When propagating, the Lamb wave propagates at 90° to the normal of the inspection surface and fills the thin plate with elliptical particle vibrations. Depending on the material thickness and the inspection frequency, the Lamb wave vibration exists in different numbers of layers and propagates at a speed lower than the Rayleigh wave to close to the longitudinal wave. 8.1.2 Lamb waves are most effective for materials as thick as 5 wavelengths (based on the Rayleigh wave speed of thick specimens of the same material), and can simultaneously detect surface defects on the inspection surface and its opposite surface. Changes in the thickness of the inspected object will lead to changes in the vibration mode of the Laem wave. 8.1.3 Laem waves can be used to measure the thickness of plate-shaped inspected objects, detect defects such as delamination and cracks, and inspect the bonding quality of composite panels. 8.2 Calibration
8.2.1 The phase velocity of the Laem wave is related to the frequency of the ultrasonic wave and the thickness of the inspected object, and is also related to the incident angle of the incident longitudinal wave. The required reference reflector can be a reflector with different thicknesses or an artificial reflector. The scanning line on the fluorescent screen should be calibrated according to the distance from the probe to the reference reflector on the comparison test block.
GB 11343-89
8.2.2 To obtain a calibration indication from the reflector, the applicable Laem wave type and mode should be selected with the maximum allowable defect amount. 9 Recording and reporting of inspection data
Each inspection shall be recorded as follows: a.
Name of workpiece and date of inspection;
Name and qualification level of operator;
Name, manufacturer, model and serial number of the instrument used; type of coupling agent, length of probe cable, placement of manual scanning or automatic scanning, type of probe, frequency, chip size, vibration mode of wedge and sound beam; reference standards and calibration data required to repeat this inspection; signal data or inspection results required to be recorded, including: number, type, size and location of defects. 9.2 Write an inspection report according to the specific inspection requirements of the inspection object or the inspection requirements of the standard. Additional notes:
This standard is proposed by the Ministry of Machinery and Electronics Industry of the People's Republic of China. This standard is under the jurisdiction of the National Technical Committee for Standardization of Nondestructive Testing. This standard is drafted by the Shanghai Institute of Materials. The main drafters of this standard are Mi Zhongyu, Chen Zhunian and Chen Jinbao. 115
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