Multifunctional Induction Coil Sensor for Evaluation of Carbon Content in Carbon Steel

Carbon steel has proven to be an important structural and functional material that plays an irreplaceable role in the worldwide economy. The influence of carbon on the mechanical and magnetic properties of the steel is well understood. Thus, the precise knowledge of the amount of carbon content in steel is crucial. Magnetic Barkhausen noise (MBN), magnetic hysteresis loop (MHL), and impedance measurements are reliable tools to assess carbon content. In this work, a multifunctional induction coil sensor used for MBN, MHL, and impedance measurements is designed and optimized. A multifunctional measurement system using the optimized induction coil is employed to measure MBN, MHL, and impedance signals. The parabolic dependence of the maximum value of MBN envelope on carbon content in steel is theoretically analyzed and experimentally verified. Coercive field and remanence from MHL measurements as well as the maximum impedance value are found to be proportional to carbon content and their dependence is explained with analytical simulations.