Among different nondestructive magnetic methods, barkhausen noise is a new one in evaluation of metallurgical and mechanical properties of ferromagnetic materials such as grain size, hardness and microstructure assessment as well as determination of residual stresses. The basis of the method is on the abrupt motions and rotation of domian walls in ferromagnetic materials, when magnetized under AC current. Difference in magnetic properties, due to variation in microstructure, results in the different behavior under magnetization. Barkhausen noise is related to materails magnetization behavior, which in turn, may be used to separate various microstructures. In this research, analyzing barakhausen signals, different microstructures due to the varrious heat treatments (annealing, normalizing, quenching and quench-tempering at different temperatures) were examined. The comparsion were made for position and ampliutede of the MBN peaks in the voltage-magnetic field strength diagram. The results indicate the BN technique can be succsessfully used to separate the microstructures

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