Reduction of lift-off effects for pulsed eddy current NDT

The lift-off effect is commonly known to be one of the main obstacles for effective eddy current NDT testing as it can easily mask defect signals. Pulsed eddy current techniques, which are believed to be potentially rich of information, are also sensitive to the effect. An approach using normalisation and two reference signals to reduce the lift-off problem with pulsed eddy current techniques is proposed. Experimental testing on the proposed technique and results are presented in this report. Results show that significant reduction in the effect has been achieved mainly in metal loss and sub-surface slot inspection. The technique can also be applied for measurement of metal thickness beneath non-conductive coatings, microstructure, strain/stress measurement, where the output is sensitive to the lift-off effect.     

脉冲涡流和电磁声换能器双探头无损检测

在许多情况下，只应用一种NDT技术存在不足，这就迫使NDT操作人员使用一种以上的技术以保证检测出危害被检物使用寿命或功能的缺陷。但分别实施多种技术的检测，就会延长检验时间。介绍了一种新的NDT设施，采用两种不同的非接触无损检测技术进行互补，即电磁声换能器（EMAT）和脉冲涡流（PEC）探头。检测结果表明，脉冲涡流和电磁声换能器因是非接触，所以可应用于材料生产过程中的自动在线检验，也可用于在役检验。     

Study of ultrasonic phased array inspection imaging technology for NDT

A research about the ultrasonic phased array imaging principle from A-scan signal to B-scan image for non-destructive testing （NDT） was conducted in this paper, the ultrasonic phased array inspection imaging system used in industrial field was developed and the experiment was performed on the steel testing block by the system with 64 elements, 5 MHz phased array transducer. Experimental results show that the flaws could be accurately detected and the flaws size could be estimated from the B-scan images, and the B-scan images could clearly show the location of the flaws, but the quality of B-scan images needs to be enhanced by digital signal processing and controlling dynamic focusing for improving the image resolution.     

国产涡流检测设备在轧辊磨削及检查中的应用

简述为提高轧辊使用寿命 ,降低生产成本 ,对在役轧辊实施自动检测的重要意义。介绍了上海宝钢益昌薄板有限公司采用的国产涡流自动检测设备的组成和功能。该厂采用该技术后 ,减少了轧辊磨削量 ,避免了爆辊事故 ,取得了较好效果。     

FGH96、FGH97粉末盘的无损检测

通过对FGH96粉末、FGH97粉末镍基高温合金涡轮盘、篦齿盘无损检测方法研究,确定了粉末盘超声检测和荧光检测工艺。通过检测结果研究发现,热等静压+锻造态合金有利于超声检测,并发现了缺陷显示;直接成型热等静压态合金有利于荧光检测,并发现了缺陷显示。     

Image acquisition techniques for automatic visual inspection of metallic surfaces

This paper provides an overview of three different image acquisition approaches for automatic visual inspection of metallic surfaces. The first method is concerned with gray-level intensity imaging, whereby the most commonly employed lighting techniques are surveyed. Subsequently, two range imaging techniques are introduced which may succeed in contrast to intensity imaging if the reflection property across the intact surface changes. However, range imaging for surface inspection is restricted to surface defects with three-dimensional characteristics, e.g. cavities. One range imaging approach is based on light sectioning in conjunction with fast imaging sensors. The second introduced range imaging technique is photometric stereo.     

Study on defect classification in multi-layer structures based on Fisher linear discriminate analysis by using pulsed eddy current technique

Pulsed eddy current (PEC) is an emerging non-destructive testing technique with wide application potential. In this study, defect parameter identification in multi-layer structures is examined by using the PEC technique, and a Fisher linear discriminate analysis (FLDA)-based defect classification method is proposed. Defect localization and shape identification are investigated, and defects on the surface and subsurface of the third layer are discriminated. The time domain characterization method is introduced and researched by using the peak time and zero-crossing time of PEC response signals, the principal component analysis algorithm and the FLDA method. The feature extraction results of the three methods are used as the input values of support vector machine for defect classification and feature extraction, and the classification methods are compared. Theoretical analysis and experimental results show that the proposed method can contribute to effective classification for defect parameter identification.     

铁路钢轨的修磨及修磨用砂轮

铁路机车速度的提高对钢轨的材料和尺寸磨损提出了更高的要求。为了适应这种提速的要求,必须对新铺设的钢轨进行预防性修磨处理,并对在线使用的钢轨必须进行修磨,从而消除钢轨中固有的缺陷、钢轨顶面的不平顺以及钢轨焊接头的不半顺和钢轨的疲劳破坏层。通过对钢轨的修磨可减少由于滚动接触疲劳引起的钢轨损伤,减少钢轨侧面磨损,可延长钢轨的使用寿命0．5～1倍。本文分析了铁路钢轨产生磨损的原因和磨损的种类,介绍了钢轨的修磨方法、修磨工艺和修磨设备,提出了钢轨修磨用砂轮的基本设计原则,同时对砂轮的生产工艺和配方进行了简要介绍。     

Ultrasonic C-Scan and shearography NDI techniques evaluation of impact defects identification

The new all-composite wing for semi-aerobatic sport and training aircraft is being developed in the Czech aircraft industry. The typical outer composite structure of this wing is sandwich with carbon skins in combination with honeycomb. This new composite structure is designed in accordance with CS-23 airworthiness requirements. The NDI techniques for reliable detecting of manufacture or in-service defects (disbonding, defects from impact, etc.) are therefore, necessary. This paper compares the results of visual, ultrasonic C-Scan and laser shearography impact damage assessment and determination of sandwich panels, which were cut out from sandwich skins of this developmental wing. Considering the reliability, simplicity and rapidity of each technique and with the digital indicator measurement as a base, the laser shearography is evaluated as the most suitable method for that purpose.     

加氢裂化在役高压空冷器翅片管束的涡流检测

针对炼油加氢高压空冷器翅片管的腐蚀特点,采用远场涡流和常规涡流检测技术相结合的方法进行检测。重点介绍了在役空冷器翅片管的涡流检测方法,并将检测结果和解剖结果进行了对比验证。对此表明,采用远场涡流和常规涡流相结合的方法可以比较准确可靠地检测出空冷器翅片管的腐蚀情况,为判断空冷器的使用情况提供了可靠的依据。     

工艺因素和组织对高速动车车轮断裂韧性的影响

针对欧洲高速动车使用的DB920车轮进行了工艺实验和实验室实验。结果表明,DB920车轮轮辋部位组织主要为少量铁素体和细珠光体,当组织中的铁素体比例较高且呈网状分布时,在进行断裂韧性评价实验时易出现撕裂状断口,在撕裂带侧面有大量韧窝,断裂韧性值(KQ)较高;相反,当铁素体比例较低时,断面相对平整,断裂方式以沿晶断裂和解理断裂为主,断裂韧性较差。组织分析和有限元模拟分析结果表明:喷水冷却时,轮辋处的冷却速度自踏面向内不断降低,冷速越慢,相变后生成铁素体比例就越高,断裂韧性也就越好。结合连续冷却实验的结果估算,对此成分车轮钢而言,当冷速大于1℃/s时,相变后不能获得足够的铁素体以保证此区域的断裂韧性。     

水冷壁管漏磁/超声无损检测机器人设计

根据电站锅炉水冷壁管的缺陷特征和运行环境,研究了管壁内外表面缺陷和壁厚减薄的磁性与超声波融合的无损检测方法。研制了一种能在管壁表面自动爬行的高效无损检测机器人系统,开发了相关的爬行机器人、磁化装置、检测装置、控制系统和缺陷数据分析与可视化软件。试验证明,磁性检测装置能完成锅炉在役管道的普查和缺陷定位,超声检测能有效实现局部缺陷的定量检测。该检测机器人系统具有很大的实用和推广价值。     

精密管棒材数字成像无损探伤和测量系统

精密管材和棒材广泛用于核能和航空航天等领域,其细微缺陷探伤和尺寸精密测量极为重要。为此研制了精密管棒材数字成像无损探伤和测量系统。该系统由超声纵、横向缺陷探伤、超声尺寸测量、涡流探伤等子系统组成,实现了管材内壁、外壁纵横向缺陷超声探伤,棒材内部缺陷超声纵波探伤,棒材纵向缺陷超声横波探伤;棒材周向、径向缺陷超声横波探伤;管材壁厚超声测量,管材、棒材直径超声测量,管材、棒材椭圆度超声测量;管材、棒材缺陷涡流穿过式探伤及异物(渗碳等)检测,管材、棒材材料背景噪声穿过式涡流检测,管材、棒材旋转点式涡流探伤。各检测子系统均依据轴向编码器和周向编码器进行缺陷检测和尺寸测量的时基线记录显示、B扫显示和C扫成像显示,实现了高灵敏度、高分辨力、高可靠性的管材和棒材无损检测。     

Feature extraction and selection for defect classification of pulsed eddy current NDT

Pulsed eddy current (PEC) is a new emerging nondestructive testing (NDT) technique using a broadband pulse excitation with rich frequency information and has wide application potentials. This technique mainly uses feature points and response signal shapes for defect detection and characterization, including peak point, frequency analysis, and statistical methods such as principal component analysis (PCA). This paper introduces the application of Hilbert transform to extract a new descending feature point and use the point as a cutoff point of sampling data for detection and feature estimation. The response signal is then divided by the conventional rising, peak, and the new descending points. Some shape features of the rising part and descending part are extracted. The characters of shape features are also discussed and compared. Various feature selection and integrations are proposed for defect classification. Experimental studies, including blind tests, show the validation of the new features and combination of selected features in defect classification. The robustness of the features and further work are also discussed.     

大型立式储罐综合检测技术

介绍了我国大型立式储罐的检测现状。分析了几种无损检测新技术，如声发射检测技术、低漏磁检测技术、低频涡流检测技术以及自动超声波爬壁检测技术的特点和应用范围。提出了融合多种检测技术的储罐综合检测与评价流程，对新技术的应用前景和效益作了分析，有助于推动大型立式储罐的经济、可靠和全面检测。     

Rail flaw detection: overview and needs for future developments

Rail Flaw Detection has an important part to play in ensuring the safety of the world's railroads. Recent accidents caused by broken rails have focused attention on the technologies that enable the detection of flaws in railroad rail. This paper reviews the technologies currently employed, along with examples of recent field applications. Some of the ongoing advancements and options for the future are also discussed.     

齿轮环焊缝超声检测系统的研制与应用

变速箱齿轮高能束环焊缝的质量直接影响到整车的安全性。根据超声波检测原理,研制出一套超声波C扫描齿轮环焊缝检测系统。论述了超声探头、主机和检测软件等系统组成。实验室和现场验证表明,该系统能够检测出Ф0．5mm平底孔当量缺陷;对焊缝熔深的C扫描测量误差≤0．2mm,为保证齿轮质量提供了较好的手段。     

浅谈检化验系统设计在管理体系认证中的延伸及应用

介绍了主要基于管理模式、仪器自动化、智能化及信息化等方面的检化验系统设计思路。阐述了检化验设计在质量管理、环境管理、职业健康安全管理体系认证的重要性。有针对性地提出了工艺设计的原则，与建筑、结构、通风、给排水、电气等专业的接口关系，从本质上提高设计质量，降低设计及后期使用的风险。紧跟行业发展步伐，不断优化设计理念，对接管理体系认证审核及相关需求，延伸设计服务的影响力。     

浅谈检化验系统设计在管理体系认证中的延伸及应用

介绍了主要基于管理模式、仪器自动化、智能化及信息化等方面的检化验系统设计思路.阐述了检化验设计在质量管理、环境管理、职业健康安全管理体系认证的重要性.有针对性地提出了工艺设计的原则,与建筑、结构、通风、给排水、电气等专业的接口关系,从本质上提高设计质量,降低设计及后期使用的风险.紧跟行业发展步伐,不断优化设计理念,对接...     

钢腐蚀脉冲涡流检测系统的研制与应用

为解决带包覆层钢腐蚀检测的技术难题,根据脉冲涡流检测原理,研制出一套脉冲涡流钢腐蚀检测仪。详细论述了传感器、主机和检测软件等检测系统的组成。实验室和现场试验表明,该系统能够穿透铝和不锈钢等常见管道保护层材料,检测出120 mm包覆层厚度下10%的钢腐蚀变化。钢腐蚀脉冲涡流检测技术为在线检测提供了新的手段。