• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2017, Vol. 53 ›› Issue (2): 11-19.doi: 10.3901/JME.2017.02.011

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Grain Size Measurement in Low Carbon Steel Sheets by Laser Ultrasonics

YIN Anmin1, YANG Quan2, HE Fei2, WANG Xiaochen2, DONG Feng2, WANG Yanlong2, SHU Xuedao1   

  1. 1. Faculty of Mechanical Engineering & Mechanics, Ningbo University, Ningbo 315211;
    2. National Engineering Research Center of Flat Rolling Equipment, University of Science and Technology Beijing, Beijing 100083
  • Online:2017-01-20 Published:2017-01-20

Abstract: Laser ultrasonics, a technique based on the generation of ultrasonic waves by a pulsed laser and on their detection by a laser interferometer, can be used to determine grain sizes in steels. The absolute values of the average grain size can be calculated directly from the attenuation measurements of ultrasonic longitudinal bulk waves. The general methods of attenuation measurements are computed based on the amplitude of longitudinal waves. In fact, the amplitude as only one value is infected by the noise. Besides, the attenuation should be considered as the energy reduction. The method of time domain energy is proposed to compute the attenuation. The results indicate that time domain energy can improve the accuracy of the grain size prediction. The laser ultrasonic technique may be incorporated online for direct measurements of grain size during steel production.

Key words: grain size, laser ultrasonics, low carbon steel sheets, time domain energy attenuation