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GB/T 20935-2025: Metal materials - Method of electromagnetic acoustic inspection
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Std ID	Version	USD	Buy	Deliver [PDF] in	Title (Description)
GB/T 20935-2025	English	439	Add to Cart	4 days [Need to translate]	Metal materials - Method of electromagnetic acoustic inspection
GB/T 20935.1-2018	English	279	Add to Cart	3 days [Need to translate]	Metal materials -- Method of electromagnetic acoustic inspection -- Part 1: Standard guide for electromagnetic acoustic transducers (EMATs)
GB/T 20935.1-2007	English	479	Add to Cart	3 days [Need to translate]	Method of electromagnetic acoustic inspection for metal materials -- Part 1: Standard guide for electromagnetic acoustic transducers (EMATs)

GB/T 20935-2025: Metal materials - Method of electromagnetic acoustic inspection

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ICS 77.040.20 CCSH26 National Standards of the People's Republic of China Replaces GB/T 20935.1-2018, GB/T 20935.2-2018 and GB/T 20935.3-2018 Electromagnetic ultrasonic testing methods for metallic materials Published on 2025-08-29 Implemented on 2026-03-01 State Administration for Market Regulation The State Administration for Standardization issued a statement.

Table of Contents

Preface III Introduction IV 1.Scope 1 2 Normative References 1 3.Terms and Definitions 1 4.Detection Principle 2 5 General Requirements 4 6.Testing equipment 5. 7 Sample 7 8.Detection Methods 7. 9.Result Judgment 10. 10 Test Report 11 Appendix A (Informative) Characteristics of Electromagnetic Ultrasonic Testing Technology 12 Appendix B (Informative) Typical Applications of Electromagnetic Ultrasonic Technology 15 Reference 17

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1.Structure and Drafting Rules of Standardization Documents". Drafting. This document integrates and revises GB/T 20935.1-2018 "Electromagnetic ultrasonic testing methods for metallic materials - Part 1.Electromagnetic ultrasonic transducers" Guide to Electromagnetic Instruments, GB/T 20935.2-2018 "Metallic Materials Electromagnetic Ultrasonic Testing Methods Part 2.Utilizing Electromagnetic Ultrasonic Transducer Technology" Methods for Ultrasonic Testing, GB/T 20935.3-2018 "Metallic Materials Electromagnetic Ultrasonic Testing Methods Part 3.Using Electromagnetic Ultrasonic Testing" A method for ultrasonic surface inspection using acoustic transducer technology. Compared with GB/T 20935.1-2018, GB/T 20935.2-2018 and GB/T 20935.3-2018, this document has the following changes except for structural adjustments. Aside from editorial changes, the main technical changes are as follows. a) The scope of application has been changed (see Chapter 1, Chapter 1 of GB/T 20935.1-2018); b) The detection principle has been changed (see Chapter 4 of GB/T 20935.1-2018 and Chapter 4 of GB/T 20935.2-2018). Chapter 4 of GB/T 20935.3-2018); c) General requirements have been added (see Chapter 5); d) Additional testing equipment was added (see Chapter 6); e) Additional samples were added (see Chapter 7); f) The detection method has been changed (see Chapter 8, Chapter 9 of GB/T 20935.2-2018, and Chapter 9 of GB/T 20935.3-2018). (10 chapters). Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents. This document was proposed by the China Iron and Steel Association. This document is under the jurisdiction of the National Steel Standardization Technical Committee (SAC/TC183). This document was drafted by. Steel Research Nake Testing Technology Co., Ltd., Wuhan Zhongke Innovation Technology Co., Ltd., and Hengyang Valin Steel. Pipeline Company Limited, Southwest Jiaotong University, Northwest Branch of China Oil & Gas Pipeline Network Corporation, Jiaxing Special Equipment Inspection and Testing Center Institute, Jiangsu Dayang Precision Forging Co., Ltd., Guangdong Special Equipment Inspection and Research Institute, Metallurgical Industry Information and Standardization Research Institute. The main drafters of this document are. Zhang Jianwei, Lin Guanghui, Liu Jilin, Gou Guoqing, Xu Chenchen, Yang Jianhua, Song Yinsheng, Li Xufeng, and Wang Yongfeng. Han Zhixiong, Zhang Li, Jin Junjun, Wang Binbin, Luo Weijian, Liu Guanglei, Jin Yaohui, Fang Huajun, Chen Bing, Wang Lei, Yang Bo, Qiu Feifei, Liu Tao, Guo Mocheng Zhang Guangxin, Luo Chunlang, Xia Peng, Xu Lei, Fan Hong, Xue Jianzhong, Guo Bicheng. The document replaced by this document has been released in the following versions. ---GB/T 20935.1, first published in.2007, first revised in.2018; ---GB/T 20935.2, first published in.2009, first revised in.2018; ---GB/T 20935.3, first published in.2009, first revised in.2018.

introduction

Ultrasonic technology has firmly established its position in the field of nondestructive testing. Initially, ultrasound was mainly generated through the piezoelectric effect. The conversion of electrical energy into mechanical energy is an effective method for generating ultrasound. However, its drawback is that in order for ultrasound to enter smoothly... The material under test requires a liquid as a coupling medium. When using a coupling agent, the material under test is typically immersed in the liquid or a thin layer is applied to the surface of the material. liquid. Electromagnetic ultrasonic transducers can emit and receive ultrasonic waves without contacting the material being tested. However, electromagnetic ultrasonic testing has limitations. The image is a metallic material (ferromagnetic or non-ferromagnetic). The ultrasonic transmitter of an electromagnetic ultrasonic transducer consists of a metal coil, which is placed on a metallic material. Ultrasonic waves are generated by exciting a material (ferromagnetic or non-ferromagnetic) in a steady magnetic field using an alternating current. The surface of the metallic material is affected by the alternating current... The principle of the device is to induce a current, and the current in the magnetic field is subjected to the Lorentz force to generate an oscillating stress wave (sometimes in ferromagnetic conductive materials, magnetostriction). (The combined effect of contractile force and Lorentz force). When receiving ultrasound, the conductor surface oscillates in the magnetic field, inducing a voltage in the coil. The above-mentioned... The entire exchange process occurs within the electromagnetic skin layer of the material. An electromagnetic ultrasonic transducer is a non-contact ultrasonic transmitter with excellent repeatability. and receiving system. Electromagnetic ultrasonic testing methods for metallic materials 1.Scope This document specifies the testing principles, general requirements, testing equipment, and test procedures for ultrasonic testing using electromagnetic ultrasonic transducers (EMAT). Sample, testing method, result determination and test report. This document applies to thickness measurement and surface inspection of materials (including ferromagnetic or non-ferromagnetic metallic materials) whose sound waves are generated by electromagnetic methods. For other waveforms, the detection should be performed in accordance with this document.

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included. For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies. This document. GB/T 9445 Qualification and Certification of Nondestructive Testing Personnel GB/T 12604.1 Nondestructive Testing Terminology - Ultrasonic Testing GB/T 12604.6 Nondestructive Testing Terminology. Eddy Current Testing 3.Terms and Definitions The terms and definitions defined in GB/T 12604.1 and GB/T 12604.6, as well as the following terms and definitions, apply to this document. 3.1 An electromagnetic device that converts electrical energy into acoustic energy in a magnetic field. 3.2 Lorentz forces The force experienced by an electric current in a magnetic field. Note. The Lorentz force is perpendicular to both the magnetic field and the direction of the current, which is the same principle as that of an electric motor. 3.3 The force generated by the movement of magnetic domain walls when a ferromagnetic material is magnetized. 3.4 return coil meandercoil Periodically wound, non-intersecting electromagnetic ultrasonic transducer coils with uniform spacing. 3.5 flat (spiral) coil pancake (spiral) coil A spirally wound electromagnetic ultrasonic transducer coil with uniform spacing. 3.6 bulkwave Ultrasonic waves are used in nondestructive testing to detect volumetric materials. Note. It is either a longitudinal wave or a transverse wave. ...