THE EFFECT OF PLASTIC DEFORMATION AND RESIDUAL STRESS ON MAGNETIC BARKHAUSEN NOISE SIGNALS IN MILD STEEL

摘要

This study was conducted to investigate the effects of plastic deformation on magnetic Barkhausen noise (MBN) signals in mild steel. A number of mild steel samples were subjected to different degrees of uniaxial plastic deformation up to 30% strain. Angular MBN measurements were done on those samples. The results indicated that plastic deformation introduces a magnetic easy axis depending on the degree of plastic deformation. A significant progression towards magnetic isotropy (no magnetic easy axis) was observed after heat-treating the samples at low temperatures 450°C, 475°C, and 500°C. The activation energy associated with the anisotropy decrease was calculated from the low temperature annealing results using an Arrhenius-type analysis. This was found to be 99 Kcal/mol, which is consistent with recovery-type processes.