Effects of surface stress on Barkhausen effect emissions: model predictions and comparison with X-ray diffraction studies

Abstract

A bstract-The detection of surface stress in materials is becoming increasingly important in failure analysis. In the case of ferromagnetic steels, the Barkhausen effect provides a practical tool for surface stress evaluation. However, one of the drawbacks of the method has been the lack of an underlying model theory for use in computer simulations of these effects. In recent work a model theory has been suggested and calculations of the effects of stress on the Barkhausen signal amplitude have been made. In this paper results are presented on Barkhausen measurements taken from surface modified materials and x-ray diffraction data from the same specimens. These results show a decrease in Barkhausen signal envelope amplitude with compressive stress in the surface of the material.

Effect of hardness and composition gradients on Barkhausen emission in case hardened steel

“…To assist the curve-fitting procedure (described below), the background noise was substracted from the profile in the graphs shown in the next section. As appropriate for the skin depth relationship with the excitation frequency (0.2 Hz) and the analysing frequency range (3-100 kHz), the broadband MBN signal containing multiple frequencies samples the specimen to a depth of about 0.6 mm below the surface [7].…”

Influence of applied magnetic field strength and frequency response of pick-up coil on the magnetic barkhausen noise profile

“…When a ferromagnetic material is subjected to an external varying magnetic field, a voltage signal is induced in a pick-up coil due to changes in magnetisation of material caused by the discrete movement of magnetic domain walls overcoming various pinning sites in the material [1]. This phenomenon of electromagnetic activity known as Magnetic Barkhausen noise [1][2][3]. Jiles and Suominen [3] while working on assessment of micro-hardness and residual stress observed that the skin-depth of MBN at the same analyzing frequency decreases for materials having higher specific electric conductivity and relative permeability.…”

Residual Stress State Characterization of Machined Components by X-ray Diffraction and Multiparameter Micromagnetic Methods

“…The authors found a strong effect of all parameters on the recorded Barkhausen noise except for the hardness which induced only slight changes of the signal [13,15]. Jiles and Suomen, showed that a varying compressive residual stress state in shot peened steel sample clearly influences the maximum Barkhausen Noise signal [19]. Kleber and Vincent also proved that residual stresses strongly affect the Barkhausen Noise signal in low carbon steel while an increasing dislocation density gives a minor contribution.…”

“…Non-destructive micromagnetic methods for the measurement of residual stress have been developed these last three decades [11][12][13][14][15][16][17][18][19][20]. The principle is based on the interaction of residual stress fields with the movement of domain walls, also called Bloch walls, and with domain rotations during the magnetization processes [11,21].…”