Frequency‐Dependence of Relative Permeability in Steel

A study to characterize metal plates by means of a model‐based, broadband, four‐point potential drop measurement technique has shown that the relative permeability of alloy 1018 low‐carbon steel is complex and a function of frequency. A magnetic relaxation is observed at approximately 5 kHz. The relaxation can be described in terms of a parametric (Cole‐Cole) model. Factors which influence the frequency, amplitude and breadth of the relaxation, such as applied current amplitude, sample geometry and disorder (e.g. percent carbon content and surface condition), are considered.