Estimation of magnetocrystalline anisotropy energy from Barkhausen noise measurements in API 5L steels

This paper presents experimental evidence of the correlation between the magnetocrystalline energy (MCE) and the Barkhausen noise (BHN) signal in three API 5L steel samples. The angular dependence of the MCE in each sample was determined using the r.m.s. values of the BHN signal in the time band fr om saturation to remanence, for angular positions ranging from 0 to 180 degrees, in 10-degree steps. The angular dependence of the average MCE of each steel was also estimated from the set of individual grain orientations measured by Electron Backscatter Diffraction (EBSD). The average MCEs determined from the BHN measurements and predicted from the measured EBSD microtexture data show a relatively good concordance. This agreement is explained by considering the influence that magnetocrystalline energy has on the free pole charges that appear at grain boundaries as the material goes from saturation to remanence and therefore on the irreversible nucleation and growth of domains of reverse magnetization responsible for the BHN activity in this band.