Affiliations: [a] State Key Lab for Strength and Vibration of Mechanical
Structures, Xi'an Jiaotong University, Xi'an, Shaanxi, China | [b] Institute of Fluid Science, Tohoku University, Sendai,
Japan | [c] The Kansai Electric Power Co., Fukui-ken, Japan | Université Laval, Canada | Tohoku University, Japan
Correspondence:
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Corresponding author: Zhenmao Chen, State Key Lab for Strength
and Vibration of Mechanical Structures, Xi'an Jiaotong University, Xi'an,
Shaanxi, China. Tel./Fax: +86 29 8266 8736; E-mail: chenzm@mail.xjtu.edu.cn
Abstract: Non-destructive evaluation (NDE) techniques are indispensable for
inspection of damage in structures of carbon steel, which is widely used in
many industries. In this paper, experimental and numerical studies were
conducted to investigate the electromagnetic property variations of carbon
steel Q195 due to plastic strain by using the 4-probe potential drop method and
ECT aiming at NDE applications. A series of specimens were fabricated and
uniform global plastic strains of different levels were introduced to the
specimens by tensile testing. 4-probe potential drop measurements were carried
out to obtain the conductivity information at first. It is found that the macro
conductivity is not affected significantly by the plastic strain once taking
into account the influence of the cross-sectional area reduction of the
specimens. Combining the results of numerical analysis using a code of
A_r formulation with the measured ECT signals, the
permeability of specimens with various plastic damages was evaluated through
inverse analysis. It is proved that the ECT signal change due to plastic
damages is mainly caused by the variation of permeability, which gives a good
possibility to evaluate the plastic damage with a magnetic NDE method.
