The Study on EMAT Applied in Nondestructive Testing of Elevated Temperature Material

Abstract:

Electromagnetic acoustic transducers (EMATs) has overcome many disadvantages of the traditional piezoelectric ultrasonic sensors and can be applied in elevated temperatures and on-line inspection. In an EMAT testing system, the tested material and EMAT itself make up a whole system. So the performance of EMAT is closely depended on some physical parameters of tested material. On the other hand, characteristic parameters of metallic materials are closely related to temperature, such as density, modulus of elasticity, electrical conductivity and magnetic permeability. As the temperature increases, the density of the metal material is reduced, the elastic modulus is reduced, the electrical conductivity is decreased, the magnetic permeability has a consistent increasing trend until the Curie point. Thus the EMAT detection performance affected by the change of temperature should be considered. This paper studied the effects of temperature on EMAT testing. Three materials of 20 # steel, Q235 and 16MnR were investigated. Testing temperature varies from 26 °C to 500 °C. The results show that under elevated temperature condition, EMAT echo signals still have a good waveform and stability. Meanwhile, signals are attenuated less than 2dB. It proved that the EMAT technique has a good steady performance in elevated temperature.

• Periodical: Applied Mechanics and Materials (Volume 750)
• Pages: 261-265
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.750.261
• Online since: April 2015
• Authors: Yang Zheng*, Su Jun Li, Hui Zheng
• Keywords: Attenuation of Signal, Elevated Temperature, EMATs, Good Performance, Material, Non-Destructive Testing

References

[1] Lei Shengjun, Chen Yong, Cheng Mao, Ye Yufeng. High temperature ultrasonic testing of vessels and equipment [J]. Petroleum Engineering Construction, 2008, 34 (3): 57-60.

[2] Lei Shengjun, Cheng Mao, Chen Zhongming. The influence of temperature on piezoelectric effect of ultrasonic probe. 2009, 31(1): 53-55.

[3] Wang Shujuan, Kang Lei, Zhao Zaixin, Zhai Guofu. Overview of research advances in electromagnetic acoustic transducer. Instrument Technique and Sensor. 2006(5): 47-50.

[4] Hirao M, Ogi H. EMATs for Science and Industry: noncontacting Ultrasonic Measurements. Boston: Kluwer Academic Publishers; (2003).