Barkhausen Noise Method Research Articles

Calibration Method of Measuring Heads for Testing Residual Stresses in Sheet Metal Using the Barkhausen Method.

Among non-destructive testing methods, a group dedicated to the assessment of the state of residual stresses can be distinguished. The method of measuring residual stresses using the Barkhausen noise method has many advantages, as evidenced by the number of publications. The residual stresses in metal products are important for the further processing of such metal, such as laser cutting or bending. The results presented in this work are of an experimental nature, and the presented method of calibration of measuring heads shows how various research techniques can be used to correlate results. The research was carried out for structural steel due to the market share of this type of steel. The method can be used to measure the residual stresses in ferromagnetic metal products in order to assess their directions and quantify them. A prerequisite for the use of this measurement method is that the amplitude and geometry of the Barkhausen noise are adequately correlated to the specific values of the state of stress depending on the tested steel grade or other metals. In this study, a method for calibrating measuring sensors for the residual stress measurements is presented, as developed by the authors. The method involved conducting bending tests in both numerical modeling and experimental tests. During the bending tests, changes in the magnetic field (Barkhausen noise waveform) were recorded, taking into account the state of elastic stresses. Correlating the results of the numerical calculations and Barkhausen noise measurements made it possible to determine the quantitative values of the residual stresses in the steel sheets. Thanks to the method used, very accurate measurement is possible, and the obtained results are repeatable.

The Estimation of the Stress State of the Iron Alloy Strip Material by the Barkhausen Noise Method

This paper presents the effect of the complex strain state resulting from the asymmetric rolling of TRB products on the changes and distribution of the stress state in the material. The evaluation of the stress state in the material was based on measurements of the magnetoelastic parameter (MP) using the Barkhausen magnetic noise method. The key characteristics of the material under study that enabled the use of changes in the MP parameter to assess the stress state were ferromagnetism and a lack of texture. The first of these enabled the detection of the magnetic signals produced when a magnetic field is applied to the material, causing magnetic domains to align and sudden changes in magnetization. On the other hand, the absence of texture in the material precluded the occurrence of magnetocrystalline anisotropy, which could disturb the results of measurements of the magnetoelastic parameter in the material. In order to determine these features in the material under study, its chemical composition was determined, and a phase analysis was carried out using the X-ray diffraction method. The results of these tests showed the possibility of determining the stress state of the material by means of changes in the values of the MP parameter. On this basis, it was shown that in the TRB strips studied, there is a complex state of stress, the values of which and the nature of the changes depending on the direction of the measurements carried out, as well as on the amount of rolling reduction in the studied area of the strip.

Analysis of the Microstructure and Hardness of Flake Graphite Cast Iron Using the Barkhausen Noise Method and Conventional Techniques

The new brake disc was evaluated for microstructure and hardness by the conventional destructive tests and non-destructive Barkhausen noise method (BNM). Ten non-destructive measurements were carried out in different areas of a brake disc, which were then cut out and made into metallographic test samples. Qualitative and quantitative analysis of graphite precipitates was performed to assess their volume in material matrix, anisotropy and size. Subsequently, graphs showing the relationships between selected stereological parameters of graphite precipitates and parameters determined from the RMS envelope of Barkhausen noise were elucidated. Similar relationships between hardness and parameters coming from non-destructive tests were carried out. Magnetic parameters that specified the size of a graphite precipitate was selected. In addition, repeatability studies using BNM were carried out in the areas of the material with the smallest and largest average size of graphite precipitates. A linear relationship between amplitude of BN and length of graphite flakes was found. The paper presents the possibilities of assessing the volume and size of graphite precipitates, as well as cast iron hardness using BNM.

Multigradient Characterization of the Strain in Low-Carbon Steel Components Based on Magnetic Barkhausen Noise Method

Multigradient Characterization of the Strain in Low-Carbon Steel Components Based on Magnetic Barkhausen Noise Method

Fatigue Behaviour of Medium Carbon Steel Assessed by the Barkhausen Noise Method

Abstract In this paper, an attempt to estimate the stage of the fatigue process using the Barkhausen noise method is studied. First, microstructural and static tensile tests were carried out and, subsequently, fatigue tests up to failure were conducted. After determination of the material behaviour in the assumed static and dynamic conditions, the interrupted fatigue tests were performed. Each specimen was stressed up to a different number of cycles corresponding to 10%, 30%, 50%, 70% and 90% of fatigue lifetime for the loading conditions considered. In the next step of the experimental programme, the specimens were subjected to the Barkhausen magnetic noise measurements. Various magnetic parameters coming from the rms Barkhausen noise envelopes were determined. The linear relationship betweenthe full-width at half-maximum (FWHM) of the Barkhausen noise envelope and the number of loading cycles to fracture was found. Specimens loaded up to a certain number of cycles were also subjected to a tensile test to assess an influence of fatigue on the fracture features.

Magnetic evaluation of Bauschinger effect in marine engineering steels

In the present study, the association between the magnetic behavior of steels the Bauschinger effect was evaluated. For this reason, three different grades of steel were subjected to typical Bauschinger tests involving a single reversal from tension to compression loading, for the same amount of pre-strain. The reversal compression lasted until the opposite of the pre-strain's maximal stress was reached. As a nondestructive magnetic technique for determining the magnetic properties of the examined samples, magnetic Barkhausen noise was chosen. For the characterization of the Bauschinger effect, four indicators were used, in terms of strain, stress, and energy. Mechanical stresses alter material magnetization, but linking Bauschinger factor with magmatic noise parameters has not been widely studied. Comparing Bauschinger Effect parameter values and magnetic Barkhausen methods, results show consistency with ferromagnetic samples' mechanical behavior. As Bauschinger Effect becomes more forceful, disorder density and magnetic wall anchoring decrease. A new proposed parameter, the exponent ξ, is directly related to effect rate. The magnetic Barkhausen noise method and its peak position and full width half minimum parameters can be a promising complementary measure for evaluating BE contribution in cycle loading ferromagnetic steels. Finally, the applicability of the examined techniques for the non-destructive characterization of steel degradation was discussed.

Grinding burn classification with surface Barkhausen noise measurements

Industrial Barkhausen noise (BN) measurements are commonly utilized for final quality control after machining operations such as grinding to point out grinding burns. Grinding burns might compromise the final use and fatigue lifetime of the ground component. The industrial BN method itself is based on a pre-determined threshold value of the BN rootmean-square value (RMS). Elevated RMS values indicate detrimental changes in the component. Usually, the evaluation of grinding burn severity is not carried out. In this study, real ground cylindrical samples were collected that were rejected based on an industrial quality control with a BN unit. A more detailed BN analysis was carried out for 41 individual grinding burn locations followed by X-ray diffraction based residual stress (RS) surface measurements and residual stress and diffraction peak full-width-at-halfmaximum (FWHM) depth profiles. K-means clustering was applied to profiles to label the data points related to grinding burns of different severity. Three classes of grinding burns were identified and verified by micrographs and hardness. A linear discriminant classification model was then identified between the surface BN measurement features and labeled data points. The classification results were reasonable with about 80 % classification accuracy at worst. They showed that the classes identified can be detected with the surface BN measurements. Thus, the approach presented in this paper shows great potential in the practical use of BN measurement where grinding burns can be detected and evaluated with a surface BN measurement.

Predictive Modeling of Induction-Hardened Depth Based on the Barkhausen Noise Signal.

A non-destructive verification method was explored in this work using the Barkhausen noise (BN) method for induction hardening depth measurements. The motive was to investigate the correlation between the hardness depth, microstructure, and the Barkhausen noise signal for an induction hardening process. Steel samples of grade C45 were induction-hardened to generate different hardness depths. Two sets of samples were produced in two different induction hardening equipment for generating the model and verification. The produced samples were evaluated by BN measurements followed by destructive verification of the material properties. The results show great potential for the several BN parameters, especially the magnetic voltage sweep slope signal, which has strong correlation with the hardening depth to depth of 4.5 mm. These results were further used to develop a multivariate predictive model to assess the hardness depth to 7 mm, which was validated on an additional dataset that was holdout from the model training.

Classification of Grain-Oriented Electrical Steel Sheets by Magnetic Barkhausen Noise Using Time-Frequency Analysis and Selected Machine Learning Algorithms

In this paper, a combination of Magnetic Barkhausen Noise (MBN) and several classical machine learning (ML) methods were used to evaluate both the grade and the magnetic directions of conventional and high grain oriented electrical sheets subjected to selected surface engineering methods. The presented analysis was conducted to compare the performance of two machine learning approaches, classical ML and deep learning (DL), in reference to the same MBN examination problem and based on the same database. Thus, during the experiment, 26 classical ML algorithms were used including decision trees, discriminant analysis, support vector machines, naïve Bayes, nearest neighbor, artificial neural networks and ensemble classifiers. The experiments were carried out considering a different number of recognized magnetic directions and hence the number of determined classes as well. The results of classification accuracy of the applied ML methods were compared with those obtained for the DL model presented in a previous paper. The highest accuracy was obtained for ML models based on artificial neural networks and ensemble bagged trees. However, the accuracy did not reach 89% in the best case—for the smallest number of determined classes. Nevertheless, the achieved results generally indicated an approx. 10 percent advantage of the deep learning model over the classical ones in terms of accuracy in each of the considered cases.

Martensite morphology and volume fraction evaluation of dual-phase X70 steel using magnetic Barkhausen noise technique

• The magnetic Barkhausen noise method is highly sensitive to changes in microstructure morphologies and martensite volume fraction. • The IQ treatment formed fine and fibrous martensite morphology uniformly distributed in the ferrite matrix. • The DQ treatment revealed hard martensite distributed in a ductile ferrite matrix. • The SQ treatment showed a banded morphology with a non-uniform distribution of the phases. • There are direct correlation between magnetic hardness (Hc) and mechanical hardness (HV) for each heat treatment. This paper aims to evaluate the martensite morphologies and volume fractions of dual-phase (DP) X70 microstructure (ferrite + martensite) using the Magnetic Barkhausen Noise (MBN) non-destructive technique. In order to develop different morphologies in X70 steel, three different heat treatments (intermediate quenching (IQ), direct quenching (DQ), and step quenching (SQ)) are done for half-hour. The inter-critical annealing temperature (IAT) ranges applied to the samples are from 740 °C to 820 °C. Measurements of MBN were carried out using the MikroMach instrument. Hardness measurements and microstructure examinations were conducted using a durometer and optical microscopy. Experimental results show that IQ treatment formed fine and fibrous martensite morphology uniformly distributed in the ferrite matrix. DQ treatment revealed hard martensite distributed in a ductile ferrite matrix. SQ treatment showed a banded morphology with a non-uniform distribution of the phases. Martensite Volume Fraction (MVF) and hardness get larger with IAT increases. These treatments permit obtaining the highest hardness in DQ treatment, and the lowest hardness has been identified in SQ treatment. Indeed, the MBN method has been proved to be highly sensitive to changes in microstructure morphologies and MVF. The highest MBN signal amplitude (MBNSA) for the SQ treatment has been identified at the lowest magnetic excitation field; in contrast, the lowest MBNSA for DQ treatment was located at the highest magnetic excitation field. The maximum MBNSA decreases whenever IAT increases. Finally, the direct correlation between magnetic hardness (Hc) and mechanical hardness (HV) for each heat treatment is established in this paper.

Modeling magnetization processes in steel under stress using magnetic objects

The application of ferromagnetic steel products is pervasive in society, with important applications arising in electrical steel, oil and gas pipelines, transportation infrastructure, naval structures, aircraft landing gear, and automotive components. Magnetic properties of electrical steel materials play a key role in electrical motors and transformers, with a direct impact on energy efficiency. Measurement of response to magnetization has implications for non-destructive inspection methods, such as magnetic flux leakage, magnetic Barkhausen noise, and metal magnetic memory method. Examples include flaw detection, characterization of material properties, and identification of stress state in steel. An understanding of the magnetic response of steel materials can be facilitated by the use of magnetic objects (MOs). MOs are defined as regions of relatively independent magnetic behavior, typically about the size of a grain, to which fundamental magnetic energy considerations may be applied. This Tutorial outlines mechanisms by which MOs may be applied for modeling magnetic response in steel and presents examples of their application. MOs incorporate material physical properties such as microstructure, grain size, crystallographic texture, the presence of dislocations and impurity elements, and the presence of residual stress and stress load on the component. They can also accommodate a description of the evolution of magnetic domain structure under magnetizing conditions. As the MO model incorporates fundamental physics principles, it allows estimates of physical parameters that can be used to provide insights into the connections between magnetic properties and material properties, including hardness, embrittlement, and the presence of applied and residual stress. Practical applications include non-destructive characterization of the stress state of steel and an improved understanding of magnetic processes in electrical steel. Examples where such models may be applied include magnetic Barkhausen noise and magnetic memory method for the characterization of steel materials. This Tutorial summarizes recent advances in the MO model and its applications, providing the foundation for its further development. Magnetic objects have the potential to provide fundamental explanations and could form the basis for magnetic measurements and magnetization processes, including magnetic flux leakage, magnetic Barkhausen noise, and magnetic hysteresis.

Experimental Consideration of Conditions for Measuring Residual Stresses of Rails Using Magnetic Barkhausen Noise Method.

Residual stress, a factor affecting the fatigue and fracture characteristics of rails, is formed during the processes of fabrication and heat treatment, and is also generated by vertical loads on wheels due to the weight of vehicles. Moreover, damage to rails tends to accelerate due to the continuous increase in the number of passes and to the high speed of passing vehicles. Because this can have a direct effect on safety accidents, having a technique to evaluate and analyze the residual stresses in rails accurately is very important. In this study, stresses due to tensile loads applied to new rails and residual stresses remaining in used rails were measured by using magnetic Barkhausen noise method. First, a magnetization frequency and noise band suitable for the rails were selected. Moreover, by applying tensile loads to specimens and comparing the difference in magnetization amplitudes for each load, the stresses applied to the rails by using the magnetic Barkhausen noise method were measured, and the analysis of the results was verified. Based on these results, the difference in the results for the loads asymmetrically applied according to the wheel shape was analyzed by measuring for the head parts of used rails.

Evaluation of the stress gradient of the superficial layer in ferromagnetic components based on sub-band energy of magnetic Barkhausen noise

ABSTRACT Since magnetic Barkhausen noise is very sensitive to the change of the stress or residual stress level in components, it is feasible to detect the stress or residual stress profile along the depth direction by the magnetic Barkhausen noise method. An engineering approach was used to validate a theoretical model describing the relationship between magnetic Barkhausen noise and stress magnitude. To generate stress gradients in the specimen of Q235 steel under different deflections, the four-point bending device was used. Then the detected signals obtained in the experiment were divided into different sub-bands to evaluate the stress at different depths. The testing depth was set to be around 100 μm due to the rapid exponential attenuation of the noise signals. In the experiments, the sub-band energy density showed sensitive as the loading displacement increasing. The experimental results showed that the signal energy was also sensitive to the plastic deformation of the material. Within the depth of 100 μm, the stress change was very small. The final experimental results showed that even under such small stress variations, it is sensitive and feasible to use the magnetic Barkhausen noise energy to characterise the change of stress gradients.

In-process evaluation of the grinding process using a new Barkhausen noise method

While the achievement of size and form tolerances is already state of the art for grinding, there are hardly any industrial solutions to identify thermo-mechanical process loads such as grinding burn. A system was developed, presented, and tested, which allows for the first time the in-process measurement of Barkhausen noise to indicate changes of the boundary zone’s state using a novel kind of sensor. The system enables tactile and non-contact measurement at sampling rates of up to 10 ms. During investigations on hardened shafts of 100Cr6, relevant influences on the in-process Barkhausen noise were identified and evaluated. Furthermore, cause-effect relationships between microstructural effects and the Barkhausen noise were detected.

Case depth evaluation of induction-hardened camshaft by using magnetic Barkhausen noise (MBN) method

ABSTRACT Magnetic Barkhausen noise (MBN) method is one of the non-destructive evaluating (NDE) techniques used in industry to monitor the quality of ferromagnetic products during manufacture. In this article, case depth evaluation of the camshaft lobes by this means after induction hardening is described. A routine industrial monitoring practice is found to have limitation to evaluate the thickness of this process-hardened layer. With the aid of metallography on selected samples, this uppermost layer is found to have one, or more than one microconstituents. This infers that each type possesses different physical properties in response to the MBN measurement. Consequently, the interpretation of the MBN signal/data for case depth evaluation is not straight-forward. From metallography, a qualified component should have a uniform layer of martensite with grains ≤ 50 µm and the thickness around 3.0–5.0 mm. This gives the magnetoelastic parameter (i.e. mp) in a range of 20–70 in industrial MBN measurement. The mp outside this range corresponds to either a non-martensitic type or a martensitic type with grains > 50 µm. In fact, the characteristic features of a Barkhausen burst like peak intensity, width and position can be used to categorise different microstructural conditions. Then, the case depth of the qualified components, or the thickness of the qualified martensite, can be estimated. Statistical regression decision tree model helps to divide this qualified group into three sub-groups between 3.0 and 6.0 mm, and each can be identified by the decision criteria based on the specific ranges of the mp reading, the RMS of peak intensity and the peak position. In the end, a physical model is used to show how the difference of microstructures is influencing the magnetic flux, and thus the mp. Nevertheless, more information is needed to improve the model for this application.

Research on pipeline internal stress detection technology based on the Barkhausen effect

Focusing on the requirements of pipeline in-line testing for stress concentration, mechanical scratches and corrosion discrimination, a numerical calculation and experimental verification study of the internal testing excitation of oil and gas pipelines based on the Barkhausen effect (magnetic Barkhausen noise (MBN)) is carried out. This paper uses finite element calculation to determine the optimal position of the sensor, quantitatively analyses the influence of parameters, such as the excitation structure size and excitation intensity, on the magnetisation field of the pipeline and obtains the optimal exciting parameters for acquiring continuous Barkhausen signals, which can provide references for designing the pipeline in-line inspection gauge for stress concentration. The feasibility of the continuous Barkhausen noise (CBN) method for long-distance pipeline stress detection is verified by simulating the operating conditions of the internal detector in the pipeline using dynamic rotating excitation.

Determination of surface residual stresses in carburised AISI 8620 steel by the magnetic Barkhausen noise method

Management of the residual stress state is vital for the design and production stages of carburised components in order to satisfy the technical requirements related to performance, fatigue behaviour and useful lifetime. This enforces the use of practical, reliable and time- and cost-effective stress measurement methods by manufacturers. This study aims to investigate the efficiency of the magnetic Barkhausen noise (MBN) method in rapid non-destructive determination of surface residual stresses in carburised steels. A series of AISI 8620 steel specimens with different residual stress states was prepared by altering the carburising and subsequent tempering parameters. The specimens were characterised through scanning electron microscopy (SEM) investigations and hardness measurements, and the surface residual stresses were determined using both the MBN and X-ray diffraction (XRD) methods. The results show that a good correlation exists between surface residual stress and the parameters derived from the MBN signals.

Investigation of Welded Joints Made of Construction Steel by the Barkhausen Noise Method

Steel weld seams are characterized by heterogeneity of their microstructure. Microstructure affects the nature of the distribution, sign and magnitude of residual stresses. In combination with unfavorable factors (low temperature, metal hypoductility and an unsuccessful joint form) residual stresses lead to a decrease of load carrying capacity of a whole structure. In a weld seam residual stresses are distributed in a complex way and can affect the build quality of heavy section welded structures. Monitoring of residual stresses remains a big problem. Residual stresses in welds are often evaluated only by modeling. Unfortunately, all mathematical models describe the stress state of the welded material with low accuracy. Simple quality control, the results of which can be easy interpreted, is necessary. Welded joints made by manual arc welding and by automatic submerged arc welding were investigated. Butt seams of steel sheets of different thickness have been welded. Steel was low-carbon and low-alloyed. It is often used in welded structures for various purposes, including construction, and for pipelines manufacture. The temperature range of welded structures operation is very large – from-70 to 450С. The authors studied the structure of butt weld seams by the Barkhausen noise method, which is interesting as it represents an alternative to the known methods, which characterizes the structure and stress state of material. The relationship between the weld microstructure and magnetic noise is shown. Studies have allowed us to establish the relationship between the structure and magnetic properties and to evaluate the feasibility of applying the Barkhausen noise method to welded structures.

Использование шумов Баркгаузена для определения остаточных напряжений после алмазного выглаживания патрубков высокого давления

The results of residual stress definition after a valve unit diamond smoothing of high-pressure fittings are shown. In the paper there is used Barkhausen noise method allowing the definition of the residual stress level at a great depth as compared with the X-ray method. There is presented a procedure for the definition of residual stresses according to a ratio of a magnetoelastic parameter – deformation. The advantage of the diamond smoothing as a method of FSD allowing the decrease of tensile residual stresses and the increase compression stresses on a contact surface of fittings units is shown.

Analysis of measurement conditions influence on the magnetic Barkhausen noise phenomenon


 
 
 The effectiveness of the magnetic Barkhausen noise method (MBN), used for non-destructive testing of ferromagnetic materials, depends to a large extent on a number of factors determining the measurement conditions. The use of conditions allowing the highest possible level of discrimination between the various states of the materials state is of highest importance. Therefore, this paper presents an analysis of the impact of measurement conditions on Barkhausen noise signals observed for various states of the material conditions. Taking into consideration the stochastic nature of MBN and the complex characterization of its changes, the analysis was based on the time-frequency representation of the MBN signal. The paper presents selected distributions achieved using two transformation methods. In addi- tion, the extraction methods of features allowing the quantification of complex information were given. Finally, the discrimination ability for a number of parameters and features of MBN signals were deter- mined and the obtained results were discussed.