Barkhausen noise characterisation during elastic bending and tensile-compression loading of case-hardened and tempered samples

Abstract

This study examined the Barkhausen noise (BN) response of carburising case-hardened steel with varying tempering stages. The test material was loaded in bending and in alternating loading. The aim of the study was to obtain relevant multiparameter BN data from different loading conditions and to investigate the effect of applied stress on the BN response. The test bar series was made from casehardened steel. Different tempering parameters were used to vary the surface hardness and the surface residual stresses of the studied series of test bars. In the bending tests, the samples were subjected to incrementally applied loading in the purely elastic deformation region. In addition, uniaxial stepwise loading with tensile and compressive stress was applied to selected samples simultaneously with the BN measurements. The BN measurements were performed under different loading conditions along with X-ray diffraction strain measurements in bending. The results revealed linear behaviour between the reciprocal root mean square value and the stress values obtained with strain gages and X-ray diffraction for the tempered samples.

Characterisation of In-Depth Stress State by Magnetic Barkhausen Noise on Machined Steel Acquiring Different Frequency Bands

“…It can be seen that when the information is coming from the maximum depth (band-pass filtering at low frequencies) the sample 2 shows the largest RMSmax, while the sample 3 shows the lowest RMSmax and the sample 1 shows intermediate values. According to results obtained by several authors [3][4][5][6][7], it can be deduced that the sample 2 should have the highest tensile RS, the sample 3 the most compressive RS and the sample 1 RS between the other two samples. This corresponds to the RS profile in layers 2 and 3 in Fig.…”

“…The amplitude and the number of MBN pulses depend on the number and morphology of the obstacles and on the derivative of the magnetic field applied. Moreover, there is a known effect on the MBN produced by the stress state on steel samples due to the magnetostriction energy [3][4][5][6][7].…”

“…The relationship between the MBN signal and the RS has been extensively studied in the last years [5][6][7][8][9]. However, there are only a few studies on the RS measurements at different depths due to the difficulty of separating the information coming from the different layers of the material [8,9].…”

“…On the one hand, when magnetic field is applied parallel to tensile stress direction or perpendicular to compressive stress direction, the amplitude of the MBN signal is increased. On the contrary, when it is applied perpendicular to the tensile stress direction or parallel to compressive stress direction the amplitude of the MBN signal decreases [3][4][5][6][7]. Both cases are represented in Fig.…”

“…The amplitude and the number of MBN pulses depend on the number and morphology of the obstacles and on the derivative of the magnetic field applied. Moreover, there is a known effect on the MBN produced by the stress state on steel samples due to the magnetostriction energy [3][4][5][6][7].The relationship between the MBN signal and the RS has been extensively studied in the last years [5][6][7][8][9]. However, there are only a few studies on the RS measurements at different depths due to the difficulty of separating the information coming from the different layers of the material [8,9].…”