A New Method for Evaluation of Mechanical Stress Using the Reciprocal Amplitude of Magnetic Barkhausen Noise

This paper describes a method for detecting stress in the surface of magnetic materials, such as steels, based on the measurement of magnetic Barkhausen emissions. The paper presents a simple practical linear calibration curve that can be used to determine stress, and also provides a theoretical explanation of the reason for such a relationship. The influence of elastic tensile and compressive stresses of various magnitudes on the magnetic Barkhausen emissions was studied, with the objective of developing a technique for quantitative measurements of surface stress in machined steels. The peak amplitude of the Barkhausen emissions was found to correlate with both residual and applied stress, showing a clear rising trend for transition from compressive to tensile stress. The relationship between stress dependence of the maximum differential anhysteretic susceptibility and Barkhausen peak amplitude was observed. Plots of reciprocal values 1/chi'(max) and 1/V-MBN max against stress showed a linear relationship providing a convenient method for detecting stress levels in near-surface regions from Barkhausen measurements.