Relationship between magnetic Barkhausen noise and the stresses, the hardness and the phase content of ferromagnetic materials

Magnetic Barkhausen Noise (MBN) is a phenomenon of electromagnetic energy emission due to the movement of magnetic domain walls inside ferromagnetic materials when they are locally magnetized by an alternating magnetic field. According to Faraday’s law of electromagnetic induction, the noise can be received by the coil attached to the surface of the material being magnetized and the noise carries the message of the characteristics of the material such as stresses, hardness, phase content, etc. Based on the characteristic of the noise, research about the relationship between the welding stresses in the welding assembly and the noise, the fatigue damage of the plate structure and the noise, and the influence of heat treatment and the variation of phase content to the noise are carried out in this paper.

Measurement of Hardened Depth Using Magnetic Barkhausen Noise Technique

Hardened depths on steel samples are evaluated using a non-destructive technique based on the measurement of surface magnetic Barkhausen noise (MBN). Based on the results or experiments, the relation betweeu hardened depth and MBN is found, and a conclusion that the hardened depth can be measured by the way of measuring the MBN slgnals is obtained.

Using Magnetic Barkhausen Noise Technology and Finite Element Method to Study the Condition of Continuous Welded Rails on the Darwin-Alice Springs Line

The Magnetic Barkhausen Noise （MBN） technology is a non-destructive method to measure the neutral temperature of thc CWR track. A series of in-field verifications and data comparison on Australian mainline tracks have shown the results from that system are highly accurate and reliable. The system can be an accuracy and cost-effective tool to prevent the potential buckling and break of CWR rails. The physical backgrounds and features of the system are represented in this paper. The Darwin-Alice Springs Line is a newly constructed main line in Australia which is linked from the north and middle of Australia. Originally, this rail line is designed and constructed in a ＂cost-effective＂ way to a lower price, and the key parameters are relatively low. To maintain the stability of the CWR tracks in a very harsh environment, some new technologies such as the MBN technology were utilised. From the results of neutral temperature, it is found that the majority of them are very high. Combined with the calculation and finite element analysis, these problems evidenced that it is caused by the low toe load fastening system and high sleeper spacing. After that some suggestions are given to improve the stability of the CWR on the railway line.

基于MBN技术的AISI1045钢材料磨损损伤评价研究

采用磁巴克豪森噪声(MBN)检测技术,评估AISI1045钢材料的磨损程度。通过摩擦磨损和MBN检测实验,提取了磁巴克豪森噪声信号特征值。发现随着磨损程度的增加,MBN有效值总体呈下降趋势,MBN信号事件分布越来越分散,并建立了MBN有效值与粗糙度、磨损量和残余压应力的拟合关系。实验结果表明,磁巴克豪森噪声检测技术可以对磨粒磨损、黏附磨损、疲劳磨损阶段进行明确地分类评价。

基于MBN应力检测系统的磁化电压优化分析

针对目前磁巴克豪森噪声应力检测系统在低激励频率情况下,检测信号强度不够以及稳定性不佳等问题,进行了磁巴克豪森噪声应力检测磁化电压的优化研究。以45#钢材料为实验对象,利用有限元电磁场仿真分析软件ANSYS Maxwell对励磁部分进行了仿真,分析了不同磁化电压下的试样磁化效果。在同一励磁频率下,通过比较不同磁化电压对磁巴克豪森噪声检测信号的影响,得到了磁巴克豪森信号与磁化电压之间的关系,确定了最佳磁化电压。实验结果表明,在采用低激励频率保证检测深度的前提下,当磁化电压幅值处于7 V时,磁巴克豪森噪声信号强度高,对应力损伤检测的灵敏度高,稳定性佳,分辨率最高,且同应力的拟合度好,说明低激励频率条件下的磁巴克豪森噪声应力检测系统的检测能力得到了改进。

软磁材料磁巴克豪森噪声测量系统与影响因素研究

磁巴克豪森噪声信号(MBN)常用来进行材料的无损检测,低频磁场激励下软磁材料的MBN可以用来研究实际工况下此类材料的形变、应力和缺陷等。为此建立了一种可以同时测量软磁材料MBN和磁滞回线的测量系统,包括励磁模块、信号检测模块和信号处理模块。这些模块实现了不同激励信号的生成,且能够对测得的高频MBN信号进行检测和分析处理。利用所研发的实验平台测量了非晶合金、硅钢片等软磁材料的磁场强度、磁感应强度和MBN信号,并对信号进行了放大、滤波和平滑等处理。之后绘制了MBN的包络曲线和MBN能量环,分析了外加磁场强度、激励频率和感应线圈方式对材料MBN包络的影响规律。发现MBN双峰包络随着磁场强度增加而增加,随着激励频率f mag的增加而变大,但到达一定频率后不再变化;而MBN包络受两种感应线圈影响的主要体在第一个峰值上。研究结果为开展软磁材料MBN特性研究奠定了基础。

磁巴克豪森噪音(MBN)法对产品厚度测量的影响

本文试图说明通过变化被测产品横截面和标定试块的厚度做出依据巴克豪森噪音法测量产品残余应力的结论。将测量和比较不同试块厚度获取的RMS值和巴克豪森脉冲的整体数目作为巴克豪森噪音参数,间接有效地反映了试块各种横截面厚度对巴克豪森噪音电平的影响。文中还分析了磁化频率和磁化电流对灵敏度的影响。

基于能量重构的MBN材料硬度检测算法研究

传统硬度测试方法会损伤材料,采用一种无损检测方法即磁巴克豪森噪声(MBN)法测试不同硬度的低合金钢试件。根据MBN信号分布特点,采用基于小波处理的全局阈值部分重构算法,对信号降噪后,提取能量特征,得到能量归一化分布图。实验表明:该算法优于传统阈值去噪法;MBN信号与硬度有着很高的相关性;不同子频带的能量归一化比例反映了材料硬度变化的特征;不同硬度材料的近矫顽力场强分布呈现一定规律。

基于MBN的便携式RPV钢辐照脆化检测系统设计

反应堆压力容器(Reactor Pressure Vessel,RPV)长期工作在强中子辐照环境下,材料会受到辐照损伤,从而影响其使用寿命。针对这一问题,基于磁巴克豪森噪声(Magnetic Barkhausen Noise,MBN)效应原理,建立巴克豪森传感器的三维仿真模型,仿真结果验证了传感器结构的有效性,确定了传感器的最优参数。同时以TMS320F28335开发板为核心研制了一套针对小尺寸RPV钢辐照脆化的便携式检测系统,验证了该系统的重复性与稳定性。

Magnetic Technique Estimation of Weld Residual Stress Failure Due to Tensile Loading

In Nigeria, most welding activities are carried out by road side welders, majority of this welders are ignorant of weld residual stress and its adverse effect on weldment. Residual stress (RS) measuring device is vital in the measurement of inherent stresses in material. The aim of this research was to employ proof of principle in analyzing the weld residual stresses in a material. This was achieved by measuring samples with magnetic residual stress device and then subjecting the weld samples to mechanical tensile test with hope that materials with more residual stresses fail first. Finally the result from both procedures was compared to establish a relationship. Four (4) pieces of mild steel coupons measuring 100 × 40 × 3 mm were welded, producing two specimens, A11 and B11 of 200 × 40 × 3 mm, respectively. The specimens were measured using the Magnetic device developed and 37 signals were obtained per specimen, thereafter, the welded specimens were subjected to tensile testing and results analyzed. From the results obtained, Specimen A11 was observed to have the highest signal peak at the weld zone with RS signal of 20.3983 mV compared to B11 with 19.358 mV. While under tensile loading, it took 1.63 kN to cause failure to specimen A11 and 8.65 kN for specimen B11. From this simple experiment, it implies that the Magnetic RS device was able to mimic the behavior of residual stress and also predicted that A11 would fail first.

电镀镍膜应变的磁巴克豪森噪声试验表征

探讨了紫铜基板表面电镀镍膜拉应变的磁巴克豪森噪声测试和表征方法。首先,构建了能够同步测量电镀镍膜拉伸过程中应变和磁巴克豪森噪声信号的试验装置,获得了不同厚度镍膜中表面切向磁场强度信号,以及不同应变条件下的磁巴克豪森噪声,并从两种信号中筛选出对镍膜厚度、应变敏感的特征磁参量;最后,通过方程拟合分析了特征磁参量对镍膜厚度、拉应变的定量表征能力。结果表明,随着镍膜厚度增加,切向磁场强度的基波幅值(A_(1))呈现良好线性下降趋势;磁巴克豪森噪声特征参量(M_(max)或M_(mean))和拉应变的依赖关系服从指数型衰减函数关系。通过组合两种信号的特征参量,可以实现镍膜厚度和拉应变的定量检测。

磁巴克豪森噪声重构磁滞特征的磨削烧伤检测方法

探究轴承滚道磨削烧伤程度的磁巴克豪森噪声重构磁滞回线表征方法,通过积分重构算法将时域上的磁巴克豪森噪声信号映射到高维度的磁滞特征图像空间,再通过高维空间的磁滞特征图像揭示磁巴克豪森噪声隐含的磨削烧伤信息,实现磨削烧伤类型的识别。研究铁磁材料重构磁滞回线的重构算法,开展重构磁滞曲线随应力变化的试验研究,利用重构磁滞特征评估烧伤应力,进一步利用重构磁滞特征参数分析回火烧伤、淬火烧伤的分布特征。实验结果表明,通过重构磁滞特征参数对烧伤区域的磁巴克豪森信号进行分析,可以实现轴承滚道磨削烧伤类型的识别分类。

Effect of Ball Scribing on Magnetic Barkhausen Noise of Grain-oriented Electrical Steel

Effect of ball scribing on magnetic Barkhausen noise （MBN） of conventional grain-oriented （CGO） and high- permeability grain-oriented （HGO） electrical steel was investigated. The results showed that after ball scribing, root mean square of MBN （MBNrms） of CGO electrical steel increased 9.8% with 4 mm scribing spacing at 1.2 T, and that of HGO electrical steel apparently decreased 17.3% with 16 mm scribing spacing at 1.2 T. Through the formation and development of free magnetic poles and secondary magnetic domains due to compressive stress, primary magnetic domain space of grain-oriented electrical steel becomes smaller, which reflects as a variation of MBN in the macroscopic magnetic properties. Through correlation formula derivation of MBNrms and equilibrium distance between domain walls, effect of domain refinement on grain-oriented electrical steel was also interpreted, and optimum equilibrium distance between domain walls was determined.

基于磁巴克豪森技术的铁磁材料应力无损检测系统研究

我国工业化程度越来越高,大量机械零件长期服役,对机械结构件应力无损检测的需求增大。本文基于磁巴克豪森噪声(Magnetic Barkhausen noise,MBN)技术,搭建用于评估拉伸应力的优化无损检测系统;检测系统将电压放大器和带通滤波器由虚拟仪器Labview模拟代替,避免元器件对MBN信号的噪声干扰;通过实验分别拟合拉伸应力与MBN信号特征值均方根、波形因子、重心频率的函数关系,结果表明均方根值具有较高的置信度。

疲劳损伤磁性无损评估技术研究现状及发展前景

磁性无损检测技术是评估铁磁材料疲劳损伤以及重要结构件可靠性的重要检测手段。针对铁磁材料的疲劳损伤,介绍了几种典型的磁性无损检测技术,如磁巴克豪森噪声(MBN)、磁声发射(MAE)、漏磁(MFL)和金属磁记忆(MMM)等,对其产生机理及应用特点进行了概述;对几种磁性检测技术在疲劳损伤评估领域的研究现状以及取得的主要研究成果进行了综述;最后指出几种技术尚存的问题和进一步的研究方向,并对其发展前景进行预测。

磁巴克豪森应力检测仪研制

基于磁巴克豪森效应原理研制了一种铁磁性材料应力检测仪。该仪器包含磁巴克豪森传感器、低频连续功率放大器、低噪声小信号放大器和应力标定等多项技术,可对不同铁磁性材料应力状态进行检测与评估。工程现场实验表明所开发的检测仪器具有快速、便捷进行在役设备关键部位应力分布扫描检测的优点,且应力检测灵敏度和准确度高。

磁巴克豪森噪声重构磁滞参数的硬度测定方法

针对铁磁性材料硬度指标的快速、定量、无损检测的实际需求,揭示了材料微观结构变化对磁巴克豪森噪声信号的影响机理,提出了采用磁巴克豪森噪声重构磁滞参数作为无损定量评价材料力学性能硬度指标。采用不同热处理制度对45钢试件进行处理,得到一组具有硬度梯度的标定试件;通过比较标定试件上不同激励电压对磁巴克豪森检测系统灵敏度的影响,选择最佳激励电压;采用磁巴克豪森噪声检测技术对不同热处理标定试件进行检测,对检测信号数据进行后处理,得到磁巴克豪森噪声能量滞后周期循环曲线,即重构磁滞回线。计算不同热处理45钢标定试件4种重构磁滞参数,构建材料力学性能硬度指标、微观结构及4种重构磁滞参数之间的映射关系,得到磁巴克豪森噪声重构磁滞参数评价45钢硬度的标定模型,并对标定模型进行验证,标定模型预测硬度误差基本满足工程应用10%的指标要求。

巴克豪森噪声在电站用铁磁材料疲劳寿命评估领域的研究现状

介绍了国内外应用巴克豪森噪声检测技术在电站用铁磁材料疲劳寿命评估中的研究状况。分析、总结巴克豪森噪声与显微结构特征的内在关系以及巴克豪森噪声疲劳寿命预测曲线的研究进展,并指出该技术存在的问题和今后发展的方向。

铁磁材料疲劳损伤的磁性无损检测技术

疲劳破坏是铁磁材料构件主要的失效形式,评价铁磁材料的疲劳损伤在工程实践中具有重要的意义。磁性无损检测新技术在判断铁磁材料的疲劳损伤领域具有广阔的应用前景。综述了磁巴克豪森噪声技术(MBN)、磁声发射技术(MAE)和磁记忆技术(MMM)的检测原理、特点和应用情况,提出了三种新技术目前存在的问题和未来的发展。

基于磁巴克豪森原理的铁磁材料各向异性检测技术综述

磁巴克豪森噪声是由铁磁材料内部组织结构与磁畴的相互作用产生的一种微观电磁现象,是连接材料微观组织和宏观性能的重要桥梁,通过检测和分析磁巴克豪森噪声信号能够间接反映材料的组织结构状态。基于此原理,磁巴克豪森噪声技术发展成为一种广泛应用的无损检测方法。常规材料大多是各向同性的,意味着沿材料不同取向获得的磁巴克豪森噪声信号理论上是相同的,磁巴克豪森噪声技术可用于检测各向同性材料的硬度、弹性模量、晶粒尺寸、相含量、位错密度和渗碳层深度等。而在实际检测时,磁巴克豪森信号通常是各向异性的,造成这种现象的因素可以分为外部因素(包括外力和外磁场)和内部因素(包括晶胞参数、晶粒取向、残余应力等)。当建立外力和磁巴克豪森噪声信号的关系后,便可以通过磁巴克豪森噪声信号间接检测材料的受力状态,这在实际工程应用中是非常有价值的。通过建立内部因素和磁巴克豪森噪声信号的关系,则能够利用磁巴克豪森噪声技术检测材料的微观组织结构,对于材料的检测和制造工艺技术的反馈都具有重要意义。因此,磁巴克豪森噪声各向异性检测技术,无论是在工程应用领域还是在科研领域都具有重要价值。本文介绍了磁巴克豪森各向异性检测技术的仪器及工作原理、磁巴克豪森噪声的理论基础和分析方法,综述了借助磁巴克豪森噪声各向异性检测技术来研究材料受到的外力、外磁场和材料织构的相关进展;同时探讨了该技术在激光增材制造和激光再制造这两个热点领域中的应用潜力。