JB/T 7522-1994 Measurement method of ultrasonic velocity of materials
Some standard content:
Mechanical Industry Standard of the People's Republic of China
JB/T 7522-94
Method for measuring ultrasonic velocity of materials
Published on October 25, 1994
Ministry of Machinery Industry of the People's Republic of China
Implementation on October 1, 1995
Mechanical Industry Standard of the People's Republic of China
Method for measuring ultrasonic velocity of materials
1 Subject content and scope of application
This standard specifies the engineering measurement method of ultrasonic velocity in materials. JB/T7522-94
This standard is applicable to the use of A-type pulse reflection ultrasonic flaw detectors, through comparison with the comparison test blocks with known sound velocity, to obtain the (longitudinal and transverse) sound velocity of the material to be measured. This method is applicable to the measurement of solid sound velocity with a thickness of 5mm (including 5mn) or more. The two surfaces of the sample perpendicular to the ultrasonic incident direction (incident surface and bottom surface) have a precision better than 12, and the surface roughness is better than 3.18μm. The incident area should be larger than the sound beam size, and there should be no side wall interference.
Referenced standards
ZBY230
ZBY231
Z.BJ04001
General technical conditions for type A pulse reflection ultrasonic flaw detector Performance test method for ultrasonic flaw detection probe
Working performance test method for type A pulse reflection ultrasonic flaw detection system Ultrasonic detection system device
3.1 Detection instrument
Meet the requirements of ZBY230 Request. Any A-type pulse reflection ultrasonic flaw detector that can read the position (or distance value) of each bottom echo during measurement with an accuracy of 0.5mm from the time base of the internal scale cathode ray tube oscilloscope screen (CRT) of the instrument and has a horizontal linear error of less than 2% can be used.
3.2 Probe
A contact longitudinal wave straight probe should be used to measure the sound velocity of longitudinal waves, and a contact shear wave straight probe should be used to measure the sound velocity of transverse waves. The transducer should be of appropriate size (the chip radius should be at least several wavelengths larger), form (such as single chip or double chip) and frequency. 3.3 Coupling agent
When measuring the sound velocity of longitudinal waves, the liquid coupling agent actually used in ultrasonic flaw detection should be used, such as light and clean motor oil; when measuring the sound velocity of transverse waves, a high-viscosity adhesive such as resin or solid adhesive should be used. For porous materials, special non-liquid coupling agents (such as vacuum grease) should be used. The coupling agent must be harmless to the test material.
3.4 Comparison test block
3.4.1 The sound velocity comparison test block can be made of any sound-transparent material with a known sound velocity and should have appropriate surface roughness, shape, size and parallelism. Its typical size is a cylinder with a diameter of 10 to 30 mm and a length of 10 to 50 mm. The material attenuation of the comparison test block should be similar to that of the material being tested. 3.4.2 Other more accurate sound velocity measurement methods or comparison with water with a known sound velocity can also be used to obtain a sound velocity benchmark. 4 Determination method
Longitudinal wave sound velocity
Ministry of Machinery Industry 1 Approved on October 25, 1994
Implemented on October 1, 1995
JB/T7522-94
By comparing the longitudinal wave propagation time in the material under test with the ultrasonic longitudinal wave propagation time in a reference test block with a known longitudinal wave velocity (Vk), the longitudinal wave velocity (VL) is determined.
4.2 Shear wave velocity
By comparing the shear wave propagation time in the material under test with the ultrasonic shear wave propagation time in a reference test block with a known shear wave velocity (V), the shear wave velocity (Vs) is determined.
4.3 Requirements for multiple bottom wave method
4.3.1 Select a sample with smooth, clean, parallel surfaces. The sample size meets the requirements and the thickness measurement accuracy is = 0.02mm. 4.3.2 Place the transducer on each sample and adjust the relevant knobs of the ultrasonic flaw detector (see 2BJ04001 Horizontal Linearity Measurement Method for details) to obtain clearly distinguishable primary and secondary bottom echoes. If necessary, 5 or more bottom echoes can also be used, as shown in Figure 1. When comparing measurements, the time base adjustment of each time must remain unchanged. 4.3.3 Read (or measure with a meter) the distance between the front edge of the primary bottom echo and the front edge of the last bottom echo on the oscilloscope screen (CRT). To improve the accuracy of the reading, after the position of the front edge of the first bottom echo is determined, the gain knob can be adjusted to increase the amplitude of the last bottom echo until it is the same as the amplitude of the first bottom echo, and the position of the front edge of the last bottom echo is determined in this way. 4.3.4 The distance between two adjacent bottom echoes represents the time it takes for the ultrasonic wave to go back and forth once in the sample. For example, the distance between the primary bottom echo and the seventh bottom echo in Figure 1 represents the time it takes for the sound to go back and forth six times in the sample. That is, the number of round trips of sound N is the number of bottom waves B. minus 1:
Figure 1 Schematic diagram of multiple bottom wave method
In the comparative test, the thickness of the comparative test block and the sample, the number of round trips of sound and the number of bottom echoes do not have to be the same. 4.3.5 Calculate the unknown longitudinal wave velocity value VL of the sample according to formula 2): V,=(dNTVk)/(d,NTk)
Wherein: dk--the measured value of the distance between the first and nth bottom echoes on the comparative test block, m×10\; N——the number of round trips of sound on the measured material; T——the thickness of the measured material, mX10-3; V—the known longitudinal wave velocity of the comparative test block, m×10-\/s; d,—the measured value of the distance between the first and nth bottom echoes on the measured material, m×10\, Nk—-the number of round trips of sound on the comparative test block; Tk—the measured value of the distance between the first and nth bottom echoes on the measured material, m×10\, Thickness of test block, m×10-3. 4.3.6 Calculate the unknown shear wave velocity value Vs of the sample according to formula (3): 2
(2)
JB/T7522--94
Vs=(dkNTV)/(d,NT)
Wherein: dk---the first and nth measured values of the bottom echo distance on the comparison test block, m×10-3; N.--the number of round trips of the sound on the measurement material; T. The thickness of the measurement material, m×10
V--the known shear wave velocity of the comparison test block, m×10-3/s; d.--the first and nth measured values of the bottom echo distance on the measurement material, m×10-3: Nk--the number of round trips of the sound on the comparison test block; Tk---the thickness of the comparison test block, m×10-. 4.4 Other methods
There are many methods for accurately measuring the speed of sound in materials, most of which require the use of special or auxiliary designs, strict laboratory conditions and fine sample preparation. Other methods recommended for use in engineering measurements are shown in Appendix A (reference). 5 Report
5.1 The technical content of the sound velocity measurement report should include: the model, number and detection frequency range of the measuring instrument, the horizontal linear error of the instrument; the type, frequency, chip size, shape, number and related characteristics of the probe; coupling agent; the material, shape, size, surface condition and sound velocity of the comparison test block; the test environment temperature (℃); the material, shape, size, surface condition of the test material; the sound velocity measurement results of the test material. 5.2 The technical qualifications and name of the tester. 5.3 The test date and the date of report issuance.
JB/T7522-94
Appendix A
Determination of sound velocity of materials by pulse echo method of dual crystal probe (reference part)
AI Determination of sound velocity by pulse echo method of dual crystal probe This method uses a dual crystal probe, one crystal element is used for transmission and the other crystal element is used for reception. A2 All thickness measuring instruments using dual crystal probes can be used as sound velocity measuring instruments recommended for use in this appendix, including instruments with internal scale oscilloscope display and meter reading, with accurate calibration of the scale, and the instrument scale reading accuracy is ±0.2mm. A3 Most dual crystal probe thickness gauges obtain measurement data based on the time measurement between the incident surface echo and the first bottom surface echo. A4 Measurement method
A4.1 Calibrate the instrument and probe on a test block with known sound velocity. Adjust the scan delay and range knobs to ensure that the thickness readings on both the comparison test block and the sample to be tested can be read. For steel, for example, the sound velocity of the comparison test block is calibrated to the known sound velocity of 5900 m/s. A4.2 Measure the indicated thickness of the unknown sound velocity sample without changing the scanning delay and range of the thickness gauge. Use a micrometer or other measuring tool to measure the actual thickness of the thickness measuring part of the sample. A4.3 Calculate the measured sound velocity Vx of the sample according to formula (A1): Actual thickness
Vx= Ve ×
Indicated thickness
·(A1)
JB/T7522-94
Appendix B
Measurement of sound velocity using delay block (rod pulse echo method (reference part)
B1 Delay block (rod) pulse echo method sound velocity measurement B1.1This method is applicable to the measurement of the sound velocity of block samples, whose typical size is 10~30mm in diameter and 10mm in length. A delay block (stick) is used to connect the sample and the transducer to keep a certain distance between the chip and the sample surface and keep the probe away from the sample, so as to facilitate the measurement of the sound velocity of the sample under a specific environment (such as high temperature state), and also to facilitate the measurement of the sound velocity of thinner samples. B1.2 The material of the delay block (rod) can be the same as or different from that of the sample. B1.2.1 When the material of the delay block (rod) is the same as that of the sample, a plane step or groove should be machined on the delay block (rod), and the plane direction is perpendicular to the direction of sound beam transmission. When the sound wave is transmitted to the step or groove, the sudden change in size will produce the first echo, and the free end plane will produce the second echo. The sound velocity is calculated from the distance between the step (or groove) and the end face and the time interval between the two echoes. B1.2.2 When the material of the delay block (rod) is different from that of the sample, the first echo is generated at the interface of the delay block (rod) and the sample, and the second echo is generated at the bottom of the sample. The measured sound velocity is calculated from the relationship between the time interval between the two echoes and the thickness of the sample. B1.3 The sound velocity is calculated according to formula (B1):
Where: V—measured material sound velocity, m/s; a round-trip distance of a sound wave in the sample, m; t—sound propagation time, s.
·(B1)
Sound velocity in commonly used engineering materials
JB/T752294
Appendix C
Sound velocity in commonly used engineering materials
(reference)
The data given in Table C1 are taken from different materials, and their test conditions are not exactly the same, and the data accuracy is different, but in most engineering applications, generally speaking, these data are accurate enough. Table C1
Aluminum (cast)
Saw (Ho)
Inconel (Inconcl)
Iron (electrolytic)
Iron (cast)
Lead-antimony alloy
Monel alloy
Plastic (acrylic resin)
Fused quartz
Silver-nickel alloy
Stainless steel (347)
Stainless steel (410)
Degrees g/em
Sound velocity in engineering materials
Longitudinal wave Speed of sound
4800~6350
3500~5600
Straight wave speed of sound
22003200
The influence of temperature on the speed of sound of water
Additional instructions:
JB/T7522-94
Appendix D
Sound speed of water at different temperatures
(reference)
Sound speed of water at different temperatures
This standard is proposed and managed by the National Technical Committee for Standardization of Nondestructive Testing. This standard is drafted by Shanghai Jiaotong University. This standard was mainly drafted by Wang Yizhi
People's Republic of China
Mechanical industry standard
Method for measuring ultrasonic velocity of materials
JB/T7522-94
Published by the Machinery Standardization Research Institute of the Ministry of Machinery Industry Printed by the Machinery Standardization Research Institute of the Ministry of Machinery Industry (PO Box 8144, Beijing
Postal Code 100081)
Copyright reserved. No reproduction allowed
Format 880×12301/16
Printing sheet 3/4
Number of words 14.000
First printing in May 1995
First edition in May 1995
Print number 00,001-500bZxz.net
Price 6.00 yuan
No. 94-268
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.