Application Cases

Introduction

The field of ferromagnetic material wear evaluation is currently facing an urgent need to transition from traditional destructive and inefficient laboratory methods toward non-destructive, quantitative, and field-deployable online inspection techniques. Conventional approaches relying on friction coefficients, wear volume, and morphology observation, while capable of characterizing wear severity, suffer from low efficiency, limited applicability in industrial field settings, and inherent destructiveness due to sampling requirements. Magnetic non-destructive testing technologies, represented by Magnetic Barkhausen Noise (MBN), are gradually being introduced into tribology research due to their high sensitivity to microstructural changes (such as dislocations and grain boundaries) and stress states, coupled with low cost and operational convenience. However, current applications of MBN in wear assessment largely remain at the auxiliary level of analyzing surface quality or tribological behavior, lacking quantitative characterization of wear damage severity and accurate identification of different wear mechanisms (abrasive, adhesive, and fatigue wear). Therefore, establishing reliable quantitative models between MBN characteristic signals and wear indicators, and elucidating the coupling mechanism of plastic deformation and stress on magnetic domain evolution during the wear process, have become critical directions for advancing this field. This is of significant importance for promoting the interdisciplinary integration of non-destructive testing and tribology, and for realizing online monitoring and remaining useful life prediction of mechanical component wear states.

The Magnetic Barkhausen Noise (MBN) detection method adopted in this study is a **magnetic non-destructive testing (NDT) method** within the broader category of non-destructive testing. Their common characteristic is that they all evaluate the service condition of the inspected object by utilizing the interaction between physical fields (magnetic, acoustic, electrical, thermal, etc.) and the material, without causing damage to the object. However, MBN differs significantly from traditional NDT methods: conventional ultrasonic, radiographic, and eddy current methods are primarily used to detect macroscopic defects (cracks, pores, inclusions, etc.), whereas MBN is highly sensitive to the material's microstructure (grain size, dislocation density, number of grain boundaries) and stress state. Therefore, it is more suitable for evaluating early performance degradation (such as accumulation of plastic deformation, wear severity, and fatigue damage) rather than simply locating defects. Furthermore, ultrasonic or radiographic testing often relies on manual interpretation expertise, while MBN can establish quantitative models between extracted characteristic values (RMS, FWHM, etc.) and material degradation indicators, offering higher early warning capability and online monitoring potential. **In summary**: MBN and conventional NDT belong to the same non-destructive evaluation system, but its unique advantage lies in its ability to reveal microscopic damage and stress evolution in materials from the perspective of magnetic domain motion, providing early and quantitative detection means for progressive failure modes such as wear and fatigue. It serves as a powerful complement to traditional "defect-finding" NDT methods.

Research Direction

Friction and Wear Mechanisms of Ferromagnetic Materials, Magnetic Barkhausen Noise Non-Destructive Testing Technology, Evolution of Magnetic Parameters in Wear Zones Based on MBN-Reconstructed Magnetic Hysteresis Loops, Coupling Mechanism of Plastic Deformation and Residual Stress on MBN Signals.

Experimental objective

Through ball-on-disc friction and wear tests, the variation patterns of MBN signals in AISI 1045 steel at different wear stages were systematically investigated. Quantitative relationships were established between MBN characteristic values (RMS, FWHM) and tribological indicators (wear rate, surface roughness, wear depth) as well as residual stress. Combined with magnetic hysteresis loop reconstruction and microstructural observation, the coupling mechanism of plastic deformation and residual stress on MBN signals during the wear process was revealed. Finally, the feasibility of using MBN technology for quantitative non-destructive evaluation of wear severity and identification of wear stages in ferromagnetic materials was verified.

Testing equipment

Ball-on-disc friction and wear testing machine ,Strain gauge,Keyence VK-X1000 Laser Scanning Confocal Microscope,Bruker D8 DISCOVER X-ray Diffractometer,Rigol DG1022 Signal Generator,Aigtek ATA-309 Power Amplifier,MBN receiving coil,Data acquisition card,Electronic balance,Optical microscope.

Experimental process

A test platform was constructed using a signal generator, an ATA-309 power amplifier, an MBN sensor, and an NI data acquisition card. A sinusoidal wave with a frequency of 2 Hz and a voltage of 6 V was provided by the signal generator and amplified by the low-frequency power amplifier Aigtek ATA-309C to magnetize the specimen. Each time the disc reached the preset number of rotation cycles, the data acquisition card recorded the MBN signal at the wear scar with a sampling rate of 2.5 MHz and a band-pass filter of 0.001–1.25 MHz. The root mean square (RMS) and full width at half maximum (FWHM) of the MBN characteristic values were extracted to further evaluate the damage degree of the worn specimens.

Figure1 schematic diagram. 

Figure2  experimental setup.

Experimental results

During the wear process, RMS decreases linearly as tribological indicators such as wear rate *m*, surface roughness *Sa*, and average depth *Sz* increase. However, the relationship between RMS and residual compressive stress *σ* presents a complex nonlinear characteristic. FWHM exhibits quadratic growth with the increase of both tribological indicators and stress. The RMS and FWHM characteristic values can reflect the effects of plastic deformation and stress state on MBN signals, distinguishing among the different stages of abrasive wear, adhesive wear, and fatigue wear.

Figure3 MBN at selected cycles: (a) excitation, (b) 1500 cycles, (c) 6000 cycles, and (d) 9000 cycles.

Figure4  Relationships between the MBN characteristics and tribological indicators: (a) RMS vs. wear

rate m, (b) FWHM vs. wear rate m, (c) RMS vs. surface roughness Sa, (d) FWHM vs. surface roughness Sa.

The effectiveness of the amplifier in this experiment

1. Amplify the excitation signal output from the signal generator to provide sufficient magnetizing power for the U-shaped magnetic yoke to magnetize the specimen.

2. Drive the magnetic yoke to generate an alternating excitation magnetic field, causing the ferromagnetic material in the wear region to undergo periodic magnetization, thereby exciting MBN signals.

3. Serve as a critical excitation component of the MBN detection system, ensuring the stability and reliability of MBN signal acquisition under varying wear conditions.

Application fields

Mechanical manufacturing and equipment operation and maintenance,Special equipment safety inspection,Iron and Steel Metallurgy and Materials Processing,Transportation and Infrastructure.