Special Issue "Advanced Non-Destructive Testing in Steels"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (31 October 2017)

Special Issue Editor

Guest Editor
Prof. Evangelos V Hristoforou

Laboratory of Electronic Sensors, National Technical University of Athens, Zografou Campus, Athens 15780, Greece
Website | E-Mail
Phone: +30-2107722178
Interests: magnetic materials, magnetic sensors, electronic materials

Special Issue Information

Dear Colleagues,

Non-destructive testing (NDT) is a major issue for industrial and bio-medical applications, with several tens of billions USD in annual turnover. The technology in NDT is rapidly improving due to the development of new technologies, e.g., sensors, electronics, communications, software applications, and integration processes.

The NDT methods for steel applications are following this general trend. Year-by-year, the methods and processes become better and better, with the current state-of-the-art being the accurate detection of flaws and defects in steels in the order of microns.

The vision in steel production and manufacturing industry is the real time monitoring of the stress tensor distribution in steels, with the stress gradient components providing the metrics for steel failure prediction. Such an online measurement, in combination with the existing instruments monitoring flaws and defects in steels, can be the feedback tool for steel production and manufacturing lines, for optimizing the quality of steel products.

Apart from steel producers and manufacturers, the applications of stress gradient monitoring extend to the energy sector, concerning steel structures in both thermal and nuclear stations; the oil and gas industry piping systems and vessels under pressure; the transportation sector including shipping and ship industry as well as rails, trains, automobiles and finally in all different types of constructions involving steel.

The aim of this Special Issue is to present, on the one hand, the advances in non-destructive methods and instruments for steels in all aspects of steel production, manufacturing and use, and, on the other hand, the advances in the field of stress tensor distribution monitoring targeting the prediction of crack initiation and propagation.

The balanced contribution of both industry and academia in this Special Issue aspires to offer a comprehensive overview and roadmap in this hot industrial field.

Prof. Evangelos Hristoforou
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Non-destructive testing
  • Acoustic and ultrasonic methods
  • X-ray imaging techniques
  • Surface electromagnetic methods
  • Stress tensor distribution
  • Microstructure in steels and dislocation density
  • Steel industry and metallurgy
  • Magnetic properties of steels
  • Sensors for stress monitoring
  • Magnetic modeling in steels

Published Papers (9 papers)

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Editorial

Jump to: Research, Review

Open AccessEditorial Advanced Non-Destructive Testing in Steels
Metals 2018, 8(7), 492; https://doi.org/10.3390/met8070492
Received: 21 June 2018 / Accepted: 26 June 2018 / Published: 28 June 2018
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Abstract
The quality of steel and its corresponding products depends on the distribution and level of stress on the steel’s volume and surface, since the stress gradient is responsible for steel cracking generation and failure[...] Full article
(This article belongs to the Special Issue Advanced Non-Destructive Testing in Steels)

Research

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Open AccessArticle Characteristics of Metal Magnetic Memory Testing of 35CrMo Steel during Fatigue Loading
Metals 2018, 8(2), 119; https://doi.org/10.3390/met8020119
Received: 29 December 2017 / Revised: 2 February 2018 / Accepted: 4 February 2018 / Published: 8 February 2018
Cited by 1 | PDF Full-text (8597 KB) | HTML Full-text | XML Full-text
Abstract
The fatigue fracture of a drillstring could cause drilling disturbances and some negative impacts (e.g., economic loss) will be brought when restoring the drillstring to functionality. In order to evaluate the effects of the fatigue damage of the drillstring during drilling, a new
[...] Read more.
The fatigue fracture of a drillstring could cause drilling disturbances and some negative impacts (e.g., economic loss) will be brought when restoring the drillstring to functionality. In order to evaluate the effects of the fatigue damage of the drillstring during drilling, a new apparatus, which could monitor the load level in real-time, was built to perform the four-point bending fatigue test on 35CrMo steel, a typical material of drillstrings. Such an apparatus is based on metal magnetic memory (MMM) technology and can acquire the tangential and normal components of MMM signals. Based on the analysis of the change of surface morphology and MMM signals, it was concluded that the variation of MMM signals could be divided into four stages, which are used to accurately describe the fatigue damage process of the drillstring. Additionally, the MMM signal characteristics are introduced to especially evaluate the fatigue damage of the drillstring, including crack initiation. Furthermore, the scanning electron microscopy (SEM) results demonstrated that morphologies of fatigue fracture were related to the variation of MMM signals. Linear fitting results indicated that fatigue crack length had a good linear relationship with the characteristics, so it is feasible to monitor fatigue damage and predict the residual life of a drillstring by using MMM technology. Full article
(This article belongs to the Special Issue Advanced Non-Destructive Testing in Steels)
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Open AccessArticle Nondestructive Evaluation of Strain-Induced Phase Transformation and Damage Accumulation in Austenitic Stainless Steel Subjected to Cyclic Loading
Metals 2018, 8(1), 14; https://doi.org/10.3390/met8010014
Received: 24 October 2017 / Revised: 19 December 2017 / Accepted: 27 December 2017 / Published: 29 December 2017
Cited by 1 | PDF Full-text (5126 KB) | HTML Full-text | XML Full-text
Abstract
Strain-induced phase transformation and damage accumulation in austenitic stainless steel subjected to cyclic loading were investigated by nondestructive evaluation. The cyclic loading test was performed at various strain amplitudes at the same strain rate. The volume fraction of the strain-induced phase transformation (α′-martensite)
[...] Read more.
Strain-induced phase transformation and damage accumulation in austenitic stainless steel subjected to cyclic loading were investigated by nondestructive evaluation. The cyclic loading test was performed at various strain amplitudes at the same strain rate. The volume fraction of the strain-induced phase transformation (α′-martensite) was determined by ferrite scope and magnetic coercivity measurement. The damage accumulation and microstructure of cyclic loading specimens were characterized by microstructural observation. The cyclic hardening and cyclic softening behavior are discussed in terms of the generation of strain-induced martensite phases and a dislocation substructure at each strain amplitude. The volume fraction of the strain-induced phase increased with the strain amplitude. The increase in α′-martensite was evaluated by measuring the ultrasonic nonlinearity parameter. The presence of α′-martensite is sufficient to distort the austenitic matrix due to an interface misfit between the austenite matrix and α′-martensite, resulting in wave distortion of the longitudinal wave. From this wave distortion, super-harmonics may be generated with nucleation of the strain-induced martensite, a process that strongly depends on the strain amplitude. Full article
(This article belongs to the Special Issue Advanced Non-Destructive Testing in Steels)
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Open AccessArticle Development of Amplifier Circuit by Active-Dummy Method for Atmospheric Corrosion Monitoring in Steel Based on Strain Measurement
Received: 31 October 2017 / Revised: 14 December 2017 / Accepted: 18 December 2017 / Published: 22 December 2017
Cited by 1 | PDF Full-text (3875 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes an amplifier circuit fabricated by the active-dummy method for atmospheric corrosion monitoring based on strain measurement. The circuit was used to determine the relationship between the voltage and strain. Experiments involving the thickness reduction of low-carbon steel test pieces induced
[...] Read more.
This paper describes an amplifier circuit fabricated by the active-dummy method for atmospheric corrosion monitoring based on strain measurement. The circuit was used to determine the relationship between the voltage and strain. Experiments involving the thickness reduction of low-carbon steel test pieces induced by galvanostatic electrolysis were carried out with the amplifier circuit. The circuit was capable of accurately measuring signals induced by the thickness reduction of the test piece. Moreover, the circuit was assessed for the effects of environmental temperature drift, and was found to exhibit a high tolerance. The proposed amplifier circuit would be suitable for atmospheric corrosion monitoring in many types of infrastructure. Full article
(This article belongs to the Special Issue Advanced Non-Destructive Testing in Steels)
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Open AccessArticle Magnetic Investigations of Steel Degradation Using a Magnetic Hysteresis Scaling Technique
Received: 11 November 2017 / Revised: 16 December 2017 / Accepted: 19 December 2017 / Published: 21 December 2017
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Abstract
We report the results of magnetic measurements on austenitic stainless steels and duplex stainless steels using a magnetic hysteresis scaling technique. Unlike saturation hysteresis loops, this scaling technique, which uses a set of minor hysteresis loops, can be used in low measurement fields.
[...] Read more.
We report the results of magnetic measurements on austenitic stainless steels and duplex stainless steels using a magnetic hysteresis scaling technique. Unlike saturation hysteresis loops, this scaling technique, which uses a set of minor hysteresis loops, can be used in low measurement fields. We show that there is a universal scaling power law between minor-loop parameters, which is independent from the level of deformation. The behavior of a coefficient deduced from the scaling law was explained from the viewpoint of the morphology of a ferromagnetic phase. Full article
(This article belongs to the Special Issue Advanced Non-Destructive Testing in Steels)
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Open AccessArticle A Numerical Study on the Excitation of Guided Waves in Rectangular Plates Using Multiple Point Sources
Metals 2017, 7(12), 552; https://doi.org/10.3390/met7120552
Received: 10 October 2017 / Revised: 27 November 2017 / Accepted: 29 November 2017 / Published: 8 December 2017
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Abstract
Ultrasonic guided waves are widely used to inspect and monitor the structural integrity of plates and plate-like structures, such as ship hulls and large storage-tank floors. Recently, ultrasonic guided waves have also been used to remove ice and fouling from ship hulls, wind-turbine
[...] Read more.
Ultrasonic guided waves are widely used to inspect and monitor the structural integrity of plates and plate-like structures, such as ship hulls and large storage-tank floors. Recently, ultrasonic guided waves have also been used to remove ice and fouling from ship hulls, wind-turbine blades and aeroplane wings. In these applications, the strength of the sound source must be high for scanning a large area, or to break the bond between ice, fouling and plate substrate. More than one transducer may be used to achieve maximum sound power output. However, multiple sources can interact with each other, and form a sound field in the structure with local constructive and destructive regions. Destructive regions are weak regions and shall be avoided. When multiple transducers are used it is important that they are arranged in a particular way so that the desired wave modes can be excited to cover the whole structure. The objective of this paper is to provide a theoretical basis for generating particular wave mode patterns in finite-width rectangular plates whose length is assumed to be infinitely long with respect to its width and thickness. The wave modes have displacements in both width and thickness directions, and are thus different from the classical Lamb-type wave modes. A two-dimensional semi-analytical finite element (SAFE) method was used to study dispersion characteristics and mode shapes in the plate up to ultrasonic frequencies. The modal analysis provided information on the generation of modes suitable for a particular application. The number of point sources and direction of loading for the excitation of a few representative modes was investigated. Based on the SAFE analysis, a standard finite element modelling package, Abaqus, was used to excite the designed modes in a three-dimensional plate. The generated wave patterns in Abaqus were then compared with mode shapes predicted in the SAFE model. Good agreement was observed between the intended modes calculated in SAFE and the actual, excited modes in Abaqus. Full article
(This article belongs to the Special Issue Advanced Non-Destructive Testing in Steels)
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Open AccessArticle RBF-Neural Network Applied to the Quality Classification of Tempered 100Cr6 Steel Cams by the Multi-Frequency Nondestructive Eddy Current Testing
Metals 2017, 7(10), 385; https://doi.org/10.3390/met7100385
Received: 18 August 2017 / Revised: 13 September 2017 / Accepted: 15 September 2017 / Published: 21 September 2017
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Abstract
This article proposes a Radial Basis Function Artificial Neural Network (RBF-ANN) to classify tempered steel cams as correctly or incorrectly treated pieces by using multi-frequency nondestructive eddy current testing. Impedances at five frequencies between 10 kHz and 300 kHz were employed to perform
[...] Read more.
This article proposes a Radial Basis Function Artificial Neural Network (RBF-ANN) to classify tempered steel cams as correctly or incorrectly treated pieces by using multi-frequency nondestructive eddy current testing. Impedances at five frequencies between 10 kHz and 300 kHz were employed to perform the binary sorting. The ANalysis Of VAriance (ANOVA) test was employed to check the significance of the differences between the impedance samples for the two classification groups. Afterwards, eleven classifiers were implemented and compared with one RBF-ANN classifier: ten linear discriminant analysis classifiers and one Euclidean distance classifier. When employing the proposed RBF-ANN, the best performance was achieved with a precision of 95% and an area under the Receiver Operating Characteristic (ROC) curve of 0.98. The obtained results suggest RBF-ANN classifiers processing multi-frequency impedance data could be employed to classify tempered steel DIN 100Cr6 cams with a better performance than other classical classifiers. Full article
(This article belongs to the Special Issue Advanced Non-Destructive Testing in Steels)
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Open AccessArticle Acoustic Emission Signatures of Fatigue Damage in Idealized Bevel Gear Spline for Localized Sensing
Metals 2017, 7(7), 242; https://doi.org/10.3390/met7070242
Received: 30 May 2017 / Revised: 26 June 2017 / Accepted: 26 June 2017 / Published: 30 June 2017
Cited by 3 | PDF Full-text (7037 KB) | HTML Full-text | XML Full-text
Abstract
In many rotating machinery applications, such as helicopters, the splines of an externally-splined steel shaft that emerges from the gearbox engage with the reverse geometry of an internally splined driven shaft for the delivery of power. The splined section of the shaft is
[...] Read more.
In many rotating machinery applications, such as helicopters, the splines of an externally-splined steel shaft that emerges from the gearbox engage with the reverse geometry of an internally splined driven shaft for the delivery of power. The splined section of the shaft is a critical and non-redundant element which is prone to cracking due to complex loading conditions. Thus, early detection of flaws is required to prevent catastrophic failures. The acoustic emission (AE) method is a direct way of detecting such active flaws, but its application to detect flaws in a splined shaft in a gearbox is difficult due to the interference of background noise and uncertainty about the effects of the wave propagation path on the received AE signature. Here, to model how AE may detect fault propagation in a hollow cylindrical splined shaft, the splined section is essentially unrolled into a metal plate of the same thickness as the cylinder wall. Spline ridges are cut into this plate, a through-notch is cut perpendicular to the spline to model fatigue crack initiation, and tensile cyclic loading is applied parallel to the spline to propagate the crack. In this paper, the new piezoelectric sensor array is introduced with the purpose of placing them within the gearbox to minimize the wave propagation path. The fatigue crack growth of a notched and flattened gearbox spline component is monitored using a new piezoelectric sensor array and conventional sensors in a laboratory environment with the purpose of developing source models and testing the new sensor performance. The AE data is continuously collected together with strain gauges strategically positioned on the structure. A significant amount of continuous emission due to the plastic deformation accompanied with the crack growth is observed. The frequency spectra of continuous emissions and burst emissions are compared to understand the differences of plastic deformation and sudden crack jump. The correlation of the cumulative AE events at the notch tip and the strain data is used to predict crack growth. The performance of the new sensor array is compared with the conventional AE sensors in terms of signal to noise ratio and the ability to detect fatigue cracking. Full article
(This article belongs to the Special Issue Advanced Non-Destructive Testing in Steels)
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Review

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Open AccessReview Magnetic Hysteresis and Barkausen Noise in Plastically Deformed Steel Sheets
Metals 2018, 8(1), 15; https://doi.org/10.3390/met8010015
Received: 7 December 2017 / Revised: 26 December 2017 / Accepted: 28 December 2017 / Published: 30 December 2017
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Abstract
The magnetic properties of steels are affected by plastic deformation, because the domain wall processes magnetoelastically interact with the dislocations and the residual stresses. The evolution of the magnetic hysteresis loop and its parameters with the type and degree of straining can thus
[...] Read more.
The magnetic properties of steels are affected by plastic deformation, because the domain wall processes magnetoelastically interact with the dislocations and the residual stresses. The evolution of the magnetic hysteresis loop and its parameters with the type and degree of straining can thus provide a macroscopic signature of the underlying the mechanical and structural properties. Additional information can be achieved at a microscopic level through analysis of the Barkhausen noise, the signal generated by the stochastic flux variations associated with the discontinuous motion of the domain walls. Nondestructive methods for the structural evaluation of magnetic steels, devoted, in particular, to the investigation of work-hardening and state of internal stress following plastic straining, have therefore been developed in the literature, either through magnetic hysteresis or Barkhausen noise measurements. In this paper, we summarize significant results regarding the relationship between magnetic properties and plastic deformation in steel samples and the related experimental methods. Attention will be devoted, in particular, to the measurement and analysis of the Barkhausen noise spectral density and the way it relates to the macroscopic magnetic behavior and the structural properties. Full article
(This article belongs to the Special Issue Advanced Non-Destructive Testing in Steels)
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