Study of Magnetic Barkhausen Noise on the evaluation of case depth on carburized steel

As part of a project to identify nondestructive techniques to determine the surface hardness and case depth of carburized steel, Magnetic Barkhausen Noise (MBN) measurement have been evaluated. MBN measures the pulses generating by the interaction between the alternating current magnetization and the magnetic domain walls in the ferromagnetic material. In carburized steel, carbon atoms changes the structure of magnetic domain walls by interacting with vacancies, impurities and grain boundaries which could be used to evaluate the properties of the carburized steel. For this study, samples of 1018 and 8620 were carburized to selected hardness and case depths. MBN was determined to be an effective method to evaluate the case depth. In this paper, results of this method will be presented and discussed.