Micromagnetics

Abstract

Micromagnetic materials characterization is receiving growing industrial acceptance and application due to significant improvements in sensor technology, data processing, and ease of use. The fundamental similarity between the interaction of microstructure with dislocations and magnetic domain walls is the basis of all micromagnetic approaches. This similarity leads to correlated interactions with magnetic and mechanical loads, resulting in, for example, the classical analogy between magnetic and mechanical hardness. In practical devices, a set of micromagnetic parameters is being determined in order to obtain a unique “fingerprint” of the material. In a calibration procedure, the multiparametric fingerprint is then mathematically related to target parameters such as hardness, hardening depth, strength, yield point, or residual stress. The multiparameter approach is preferred due to the fact that several material properties affect the magnetic behavior, so that a single measuring parameter will never be a unique function of a given target property. The main challenge is that sensor and part geometry are reflected in the magnetic parameter values, which makes it hard to collect calibration-relevant knowledge across several applications. Together with a growing variety of high-performance steel grades available today, this results in a need for individual, application-specific calibration. State-of-the-art micromagnetic testing systems address this issue by means of simplified, accelerated, and interactive calibration procedures and well-selected micromagnetic parameters of increased significance. The path pursued by developers today leads towards increasingly user-friendly devices with low calibration effort.