Magnetization Time Lag Caused by Eddy Currents and Its Influence on High-Speed Magnetic Flux Leakage Testing

In high-speed magnetic flux leakage (MFL) testing, the tested workpieces pass rapidly through magnetizers. Thus, the magnetization time for workpieces is short. Because of the eddy current effect, the magnetic field inside the workpieces cannot instantly reach equilibrium, and if the magnetizing time is insufficient for the field to reach equilibrium, the MFL signals will be changed because of incomplete magnetization. In this article, the magnetization time lag caused by eddy currents and the influence of this lag on high-speed MFL testing is investigated. The time required for magnetic field to reach equilibrium in specimens, including steel bars and pipes, is obtained by theoretical calculations, finite element simulations, and experiments. The results indicate that the time required for a magnetic field inside a specimen to reach equilibrium is in the range of 50–100 ms. Using conventional magnetizers, the defect signals at testing speed of 10 m/s change because the workpiece reaches the detection zone before the magnetic field inside reaches the stable state. A simple solution is to increase the axial length of the magnetizing coil. After this procedure, signals obtained at 0.1 m/s and 10 m/s are almost identical.

DOI: 10.1080/09349847.2018.1459988

References

[1] Y. Sun and Y. Kang, Appl. Phys. Lett. 103 (18), 184104 (2013). DOI: 10.1063/1.4828556.

[2] ANS/API, SPEC 5L/ISO 3183:2007, Petroleum and Natural Gas Industries-Steel Pipe for Pipeline Transportation Systems (API Publishing Services, Washington, 2007).

[3] W. Jianbo et al., Int. J. Appl. Electromagn. Mech. 45, 193–199 (2014).

[4] S. Mandayam et al., IEEE Trans. Magn. 32 (3), 1577–1580 (1996). DOI: 10.1109/20.497553.

[5] S. Mandayam et al., Res. Nondestr Eval. (8), 233–247 (1996). DOI: 10.1080/09349849609409601.

[6] Y.-K. Shin, IEEE Trans. Magn. 33 (2), 2127–2130 (1997). DOI: 10.1109/20.582751.

[7] G. S. Park and S. H. Park, IEEE Trans. Magn. 40 (2), 663–666 (2004). DOI: 10.1109/TMAG.2004.824717.

[8] D. Zhiye et al., IEEE Trans. Magn. 44 (6), 1642–1645 (2008). DOI: 10.1109/TMAG.2007.915955.

[9] D. Zhiye, R. Jiangjun, and Y. Shifeng, Microwave Conference Proceedings. 2005.

[10] L. Yong, G. Y. Tian, and S. Ward, NDT&E Int. 39, 367–373 (2006). DOI: 10.1016/j.ndteint.2005.10.006.

[11] Z. Gan and X. Chai, International Conference on Electronics and Optoelectronics. 2011.

[12] Z. Chen, et al. IEEE Instrumentation and Measurement Technology Conference, Binjiang, 2011.

[13] J. I. Etcheverry, D. H. Ziella, and G. A. Sánchez, The 39th Annual Review of Progress in Quantitative Nondestructive Evaluation. 2013.

[14] L. Zhang et al., J. Nondestruct Eval. 34, 6 (2015). DOI: 10.1007/s10921-015-0280-1.

[15] Y. Sun et al., Insight. 57 (12), 689–696 (2015). DOI: 10.1784/insi.2015.57.12.689.

[16] J. Fengzhu et al., Insight. 51 (1), 32–35 (2009). DOI: 10.1784/insi.2009.51.1.32.

[17] W. Sharatchandra Singh et al., Meas. Sci. Technol. 19, 015702 (2008). DOI: 10.1088/0957-0233/19/1/015702.

[18] A. Einstein, Ann. Phys. 17, 891 (1905). DOI: 10.1002/andp.19053221004.

[19] S. Niikura and A. Kameari, IEEE Trans. Magn. 28 (2), 1450–1453 (1992). DOI: 10.1109/20.123968.

[20] D. J.Griffiths, Introduction to Electrodynamics, 3rd ed. (Prentice Hall, Inc.,New Jersey, 1999).

[21] C. V. Dodd and W. E. Deeds, J. Appl. Phys. 39, 2829 (1968). DOI: 10.1063/1.1656680.

[22] A. V. Oppenheim, A. S. Willsky, and S. H. Nawab, Signals and Systems, 2nd ed. (Prentice Hall, Inc., New Jersey, 1997).

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