Modeling microstructural effects on Barkhausen emission in surface-modified magnetic materials

Relationships between magnetic properties and microstructure in surface hardened steel were studied through measurements and model simulations, with the objective of developing techniques for quantitative measurements of case depth of surface hardened steels. The depth profiles of the magnetic properties were found to correlate with the hardness profile. Theoretical analysis using the hysteresis model and the stochastic model of domain wall dynamics indicates that the Barkhausen model parameters are inversely proportional to the domain wall pinning coefficient k. These relationships can be interpreted in terms of the effects of pinning site density on the local pinning field and distance of domain wall jumps which determine the Barkhausen activity.