GB/T 40730-2021Non-destructive testing—Measuring thickness by electromagnetic ultrasonic pulse-echo (English PDF)
无损检测 电磁超声脉冲回波式测厚方法
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Issued by
SAMR; SAC
Level / Type
National · Recommended
Issue date
October 11, 2021
Implementation date
May 1, 2022
Scope
GB/T 40730-2021 is the English-translated version of 无损检测 电磁超声脉冲回波式测厚方法.
GB/T 40730-2021 describes how to measure the thickness of a material with electromagnetic ultrasonic transducers, which excite and receive ultrasound through a magnet, a coil and the eddy currents induced in the part.
The thickness is obtained from the ultrasonic propagation time and the sound velocity, either for a single pass or as the time difference between repeated echoes.
The standard covers the measurement principle and types, personnel and safety requirements, the inspection process, the equipment, the test procedure, the uncertainty of the results and the inspection record and report, with annexes on the advantages and limits of the method, transverse wave velocity against temperature for common materials.
It applies to steel, non-ferrous metals and other materials from -196 °C to 800 °C. It was issued on 11 October 2021 and has applied since 1 May 2022.
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Document preview — GB/T 40730-2021
National Standard of the People's Republic of China
- ICS
- 19.100
- Classification
- J 04
Issued by: State Administration for Market Regulation; Standardization Administration of the PRC
Contents
- Foreword
- 1 Scope
- 2 Normative references
- 3 Terms and definitions
- 4 Thickness measurement principle, thickness value calculation and thickness measurement type
- 5 Personnel requirements
- 6 Safety requirements
- 7 Inspection process regulations
- 8 Testing equipment and equipment
- 9 Testing procedures
- 10 Uncertainty of measurement results
- 11 Inspection records and reports
- Appendix A (informative) The main advantages and limitations of electromagnetic ultrasonic thickness measurement
- Appendix B (Informative) Temperature of Commonly Used Materials-Transverse Wave Sound Velocity Table
- Appendix C (informative) Method of measuring material temperature-sound velocity curve with electromagnetic ultrasonic thickness gauge
- Appendix D (informative) Factors affecting the measurement uncertainty of electromagnetic ultrasonic thickness measurement results
Foreword
This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for Standardization Work Part 1: Structure and Drafting Rules of Standardization Documents" Drafting.
1 Scope
This document specifies the method of material thickness measurement using electromagnetic ultrasonic transducer to excite and receive ultrasound.
This document is applicable to steel, non-ferrous metals and other materials that use electromagnetic ultrasonic transducers with a temperature range of -196°C~800°C. Measurement of materials that emit ultrasound.
2 Normative references
The contents of the following documents constitute the indispensable clauses of this document through normative references in the text. Among them, dated quotations Only the dated version is applicable to this document; for undated reference documents, the latest version (including all amendments) is applicable to this document.
GB/T 9445 Qualification and certification of non-destructive testing personnel
GB/T 12604.1 Non-destructive testing term Ultrasonic testing
GB/T 27418 Evaluation and Expression of Uncertainty in Measurement
GB/T 34885 Non-destructive testing General rules for electromagnetic ultrasonic testing
3 Terms and definitions
The terms and definitions defined in GB/T 12604.1, GB/T 27418 and GB/T 34885 apply to this document.
4 Thickness measurement principle, thickness value calculation and thickness measurement type
4.1 Principle of Thickness Measurement
Electromagnetic ultrasound technology realizes the excitation and reception of ultrasound by means of electro-magnetic-acoustic coupling. The core transducer of electromagnetic ultrasound The parts are magnets and coils, and the basic working principle is shown in Figure 1. During the electromagnetic ultrasonic excitation process, when the coil placed above the When a transient alternating electrical signal is used, an induced eddy current is generated on the surface of the tested material, and a dynamic magnetic field is induced by the coil at the same time. The material in the eddy current region is biased magnetically Under the action of electric field and dynamic magnetic field, it is affected by Lorentz force. Since the alternating current passes through the coil, the induced eddy current is also alternating.
The Lorentz force of each particle in the material in the vortex zone is also alternating. This alternating force causes the surface particles of the material to vibrate, such as If the alternating frequency is the ultrasonic frequency band, the generated vibration is manifested as ultrasonic vibration, that is, the ultrasonic is excited in the material. If the inspected material is iron In addition to the alternating Lorentz force, magnetic materials also have alternating magnetostrictive force and magnetizing force. Under the combined action of the three forces, the material Ultrasonic vibration of surface particles produces ultrasound. The electromagnetic ultrasonic receiving process is the inverse process of excitation.
The electromagnetic ultrasonic thickness measurement method does not directly measure the thickness, but obtains the thickness of the measured object from the product of the ultrasonic propagation time and the velocity.
The propagation time is the time of one propagation of ultrasound on the thickness path of the measured object or the time difference of multiple reciprocating propagations.
Refer to Appendix A for the main advantages and limitations of the electromagnetic ultrasonic thickness measurement method.
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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 21 pages — is available in the English PDF.
Referenced standards
Normative references
- GB/T 9445Non-destructive testing - Qualification and certification of personnels
- GB/T 12604.1Non-destructive testing - Terminology - Ultrasonic testing
- GB/T 27418Guide to the evaluation and expression of uncertainty in measurement
- GB/T 34885Non-destructive testing—Electromagnetic ultrasonic testing—General principles
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Related Standards
GB/T 12604.1-2020 — Non-destructive testing - Terminology - Ultrasonic testing
GB/T 12604.10-2023 — Non-destructive testing - Terminology - Part 10: Magnetic memory testing
GB/T 12604.11-2015 — Non-destructive testing - Terminology - Terms for X-ray digital radioscopic testing
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