Investigation of Variables Affecting Impedance Plane in Eddy Current Testing of Carburized Steels

Abstract

Impedance plane is one of the most important ways for presenting results in Eddy current testing, which includes major data for evaluation of results. In this study, the impedance plane was drawn for carburized steel with different surface carbon content. The influences of temperature, fill factor, and edge effect on impedance plane were investigated. The ability of Eddy current testing for determination of surface carbon content using normalized impedance was also shown. Results demonstrate a strong relationship between normalized impedance and surface carbon content (R 2 = 0.82). Besides the effects of temperature, fill factor, and edge effect on determination of surface carbon content were investigated. The fill factor and temperature have the largest and the least effect on correlation coefficient between surface carbon content and impedance plane, respectively.

Magnetic nondestructive technology for detection of tempered martensite embrittlement

“…The impedance plane diagram can, also, be used to map the changes in EC coil impedance as a function of variations in the test sample microstructure. The details of the impedance plane calculations have been mentioned elsewhere [12,13,23]. The results of calculations for characterization of tempered microstructures are presented in Fig.…”

The Influence and Compensation Method of Eccentricity for Cylindrical Specimens in Eddy Current Displacement Measurement

“…As the previous section suggests, E will cause a bigger measured value. The impedance plane method is an effective way for presenting results in the eddy current testing [22] and can be considered as another perspective to discuss the effect of E on the eddy current displacement measurement. The normalized R and X are defined using Equation 7:…”

Electromagnetic nondestructive evaluation of tempering process in AISI D2 tool steel

“…To present EC responses, impedance plane and movement of impedance point location, which are well theoretically established [31][32][33][34], have also been used. An impedance plane diagram maps the changes in EC coil impedance as a function of discontinuities (cracks, porosity), geometric variables (edge effect, liftoff) and mechanical/microstructural properties (phase fraction, hardness, strength, toughness) of the test samples.…”