The effect of stress on magnetic Barkhausen activity in ferromagnetic steels

The author presents the results of measurements of the effect of uniaxial tensile stresses of up to 85 MPa on Barkhausen activity and magnetic properties of AISI 4130 and AISI 4140 steels. The results show that maximum Barkhausen activity occurred very close to the coercive point. The Barkhausen peak height and the total number of pulses were affected by the stress, although there was considerable scatter in some of the results so that it was not clear how the height of the AISI 4130 peak varied with stress. The differential susceptibility at the coercive point increased with tensile stress in accordance with the prediction of previous theory.<>