Special Issue "Non-Destructive Metallic Materials Testing—Recent Research and Future Perspectives"

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

Deadline for manuscript submissions: closed (30 September 2016)

Special Issue Editors

Guest Editor
Dr. João Manuel R. S. Tavares

Instituto de Ciência e Inovação em Engenharia Mecânica e Engenharia Industrial, Departmento de Engenharia Mecânica, Faculdade de Engenharia, Universidade do Porto, Porto, Portugal
Website | E-Mail
Phone: +351225081487
Interests: Computational Vision, Image Processing and Analysis, Computational Methods, Biomechanics, Product Development, Non-Destructive Testing
Guest Editor
Dr. Victor Hugo C. de Albuquerque

Programa de Pós-Graduação em Informática Aplicada, Universidade de Fortaleza, Fortaleza, Ceará, Brazil
E-Mail
Interests: applied computing; intelligent systems; visualization and interaction; pattern recognition; artificial intelligence; image processing and analysis; automation with respect to biological signal/image processing; image segmentation; biomedical circuits and human/brain-machine interaction; microstructural characterization

Special Issue Information

Dear Colleagues,

Non-destructive testing (NDT) has become extremely important in metallic materials characterization, mainly by allowing the assessment of structural, mechanical and microstructural properties in an effective and reasonable manner, in addition to maintaining the integrity of the evaluated samples and applicability in service in many cases. The aim of this Special Issue, “Non-Destructive Metallic Materials Testing—Recent Research and Future Perspectives”, is to disseminate technological advances, which have been reached through innovation and customization of non-destructive testing techniques for metallic materials, present successful application cases, and discuss possible future trends, endeavoring for faster and more reliable decision-making processes. We are pleased to invite researchers, manufacturers and end-users to contribute to this Special Issue, which also welcomes review and perspective manuscripts. Possible topics include, but are not limited to:

  • Signal processing and analysis in NDT;
  • Image processing and analysis in NDT;
  • Pattern recognition and classification in NDT;
  • 3D image reconstruction from NDT data;
  • Computational Methods and Simulation in NDT;
  • Microstructural characterization using NDT;
  • Methods and applications of NDT;
  • Software development for metallic materials non-destructive testing.

Dr. João Manuel R. S. Tavares
Dr. Victor Hugo C. de Albuquerque
Guest Editors

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 1000 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

  • Signal processing
  • Computer methods
  • Materials characterization
  • Decision-making
  • NDT techniques and applications

Published Papers (11 papers)

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Editorial

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Open AccessEditorial Non-Destructive Metallic Materials Testing—Recent Research and Future Perspectives
Metals 2017, 7(10), 430; doi:10.3390/met7100430
Received: 9 October 2017 / Revised: 10 October 2017 / Accepted: 10 October 2017 / Published: 16 October 2017
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Abstract
Non-destructive testing (NDT) has become extremely important formicrostructural characterization, mainly by allowing the assessment of metallic material properties in an effective and reasonable manner, in addition to maintaining the integrity of the evaluated metallic samples and applicability in service in many cases [...]
[...] Read more.
Non-destructive testing (NDT) has become extremely important formicrostructural characterization, mainly by allowing the assessment of metallic material properties in an effective and reasonable manner, in addition to maintaining the integrity of the evaluated metallic samples and applicability in service in many cases [...]
Full article

Research

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Open AccessArticle Evolution of Metal Surface Topography during Fatigue
Metals 2017, 7(2), 66; doi:10.3390/met7020066
Received: 2 November 2016 / Revised: 13 February 2017 / Accepted: 15 February 2017 / Published: 22 February 2017
Cited by 1 | PDF Full-text (6321 KB) | HTML Full-text | XML Full-text
Abstract
Changes in surface topography reflect the state of fatigue damage. In this paper, a new method to characterize metal surface topography during fatigue has been proposed. Firstly, we acquired surface topography images based on machine vision and separated them into roughness, waviness, and
[...] Read more.
Changes in surface topography reflect the state of fatigue damage. In this paper, a new method to characterize metal surface topography during fatigue has been proposed. Firstly, we acquired surface topography images based on machine vision and separated them into roughness, waviness, and form error images through a shearlet transform. Secondly, we constructed gray co-occurrence matrixes of the obtained surface topography images and calculated the characteristic parameters, such as contrast, correlation coefficient, energy, and entropy for all the original and separated images. Then, taking a Q235 steel specimen as an example for testing, the experimental results and theoretical analysis demonstrate that the parameter contrast increases while energy, correlation coefficient and entropy decrease gradually with number of loading circles, which reach their maximum and minimums before fracture, respectively. Full article
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Open AccessFeature PaperArticle Detection of the Magnetic Easy Direction in Steels Using Induced Magnetic Fields
Metals 2016, 6(12), 317; doi:10.3390/met6120317
Received: 30 September 2016 / Revised: 25 November 2016 / Accepted: 8 December 2016 / Published: 15 December 2016
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Abstract
Conventional manufacturing processes cause plastic deformation that leads to magnetic anisotropy in processed materials. A deeper understanding of materials characterization under rotational magnetization enables engineers to optimize the overall volume, mass, and performance of devices such as electrical machines in industry. Therefore, it
[...] Read more.
Conventional manufacturing processes cause plastic deformation that leads to magnetic anisotropy in processed materials. A deeper understanding of materials characterization under rotational magnetization enables engineers to optimize the overall volume, mass, and performance of devices such as electrical machines in industry. Therefore, it is important to find the magnetic easy direction of the magnetic domains in a simple and straightforward manner. The Magnetic easy direction can be obtained through destructive tests such as the Epstein frame method and the Single Sheet Tester by taking measurements in regions of irreversible magnetization usually called domains. In the present work, samples of rolled SAE 1045 steel (formed by perlite and ferrite microstructures) were submitted to induced magnetic fields in the reversibility region of magnetic domains to detect the magnetic easy direction. The magnetic fields were applied to circular samples with different thicknesses and angles varying from 0° to 360° with steps of 45°. A square sample with a fixed thickness was also tested. The results showed that the proposed non-destructive approach is promising to evaluate the magnetic anisotropy in steels independently of the geometry of the sample. The region studied presented low induction losses and was affected by magnetic anisotropy, which did not occur in other works that only took into account regions of high induction losses. Full article
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Open AccessArticle Ultrasonic Guided Wave Propagation through Welded Lap Joints
Metals 2016, 6(12), 315; doi:10.3390/met6120315
Received: 30 September 2016 / Revised: 30 November 2016 / Accepted: 6 December 2016 / Published: 10 December 2016
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Abstract
The objective of the research presented here is the investigation of ultrasonic guided wave (UGW) propagation through the lap joint welded plates used in the construction of a storage tank floors. The investigations have been performed using numerical simulation by finite element method
[...] Read more.
The objective of the research presented here is the investigation of ultrasonic guided wave (UGW) propagation through the lap joint welded plates used in the construction of a storage tank floors. The investigations have been performed using numerical simulation by finite element method (FEM) and tested by measurement of the transmission losses of the guided waves transmitted through the welded lap joints. Propagation of the symmetric S0 mode in the welded stainless steel plates in the cases of different lap joint overlap width, operation frequency, and additional plate bonding caused by corrosion were investigated. It was shown that the transmission losses of the S0 mode can vary in the range of 2 dB to 8 dB depending on the ratio between lap joint width and wavelength. It was also demonstrated that additional bonding in the overlap zone caused by corrosion can essentially reduce transmission losses. Full article
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Open AccessArticle Evaluation of Structural Stability of Materials through Mechanical Spectroscopy: Four Case Studies
Metals 2016, 6(12), 306; doi:10.3390/met6120306
Received: 28 September 2016 / Revised: 18 November 2016 / Accepted: 30 November 2016 / Published: 5 December 2016
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Abstract
Microstructural stability is one of the utmost important requirements for metallic materials in engineering applications, particularly at high temperatures. The paper shows how Mechanical Spectroscopy (MS) (i.e., damping and dynamic modulus measurements) permits the monitoring of the evolution of lattice defects, porosity, and
[...] Read more.
Microstructural stability is one of the utmost important requirements for metallic materials in engineering applications, particularly at high temperatures. The paper shows how Mechanical Spectroscopy (MS) (i.e., damping and dynamic modulus measurements) permits the monitoring of the evolution of lattice defects, porosity, and cracks which strongly affect the mechanical behavior of metals and sometimes lead to permanent damage. For this purpose, some applications of the technique to different metals and alloys (AISI 304 stainless steel, PWA 1483 single crystal superalloy, nanostructured FeMo prepared via SPS sintering and tungsten) of engineering interest are presented. These experiments have been carried out in lab conditions using bar-shaped samples at constant or increasing temperatures. The results can be used to orient the interpretation of frequency and damping changes observed through other instruments in components of complex shape during their in-service life. Full article
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Open AccessArticle Evolution of Mechanical Twinning during Cyclic Deformation of Mg-Zn-Ca Alloys
Metals 2016, 6(12), 304; doi:10.3390/met6120304
Received: 19 October 2016 / Revised: 24 November 2016 / Accepted: 29 November 2016 / Published: 2 December 2016
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Abstract
The present study clarifies the complex interplay between mechanical twinning and dislocation slip during low-cycle fatigue testing of Mg-Zn-Ca alloys. Temporal details of these mechanisms are studied non-destructively by in situ monitoring of the acoustic emission (AE) response powered by a robust signal
[...] Read more.
The present study clarifies the complex interplay between mechanical twinning and dislocation slip during low-cycle fatigue testing of Mg-Zn-Ca alloys. Temporal details of these mechanisms are studied non-destructively by in situ monitoring of the acoustic emission (AE) response powered by a robust signal categorization. Through the analysis of AE time series, the kinetics of deformation twinning per cycle and the overall accumulation of twinning during cyclic loading is described and its effect on fatigue life is highlighted. Full article
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Open AccessFeature PaperArticle Acoustic Emission Assessment of Impending Fracture in a Cyclically Loading Structural Steel
Metals 2016, 6(11), 266; doi:10.3390/met6110266
Received: 29 September 2016 / Revised: 20 October 2016 / Accepted: 24 October 2016 / Published: 4 November 2016
Cited by 1 | PDF Full-text (1815 KB) | HTML Full-text | XML Full-text
Abstract
Using the advanced acoustic emission (AE) technique, we address the problem of early identification of crack initiation and growth in ductile structural steels under cyclic loading. The notched 9MnSi5 steel specimens with weld joints were fatigue tested at room and lower temperatures with
[...] Read more.
Using the advanced acoustic emission (AE) technique, we address the problem of early identification of crack initiation and growth in ductile structural steels under cyclic loading. The notched 9MnSi5 steel specimens with weld joints were fatigue tested at room and lower temperatures with concurrent AE measurements. Detection of AE in ductile materials where fatigue crack initiation and propagation is mediated by local dislocation behavior ahead of the notch or crack tip is challenging because of an extremely low amplitude of the AE signal. With account of this issue, two new practically oriented criteria for recognition of different stages of fatigue are proposed on the basis of AE data: (1) a power spectrum-based criterion and (2) a pattern recognition-based criterion utilizing modern clustering algorithms. The applicability of both criteria is verified using obtained AE data. A good correspondence between AE outcomes and experimental observations of the fatigue behavior was obtained and is discussed. Full article
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Open AccessArticle Effects of Phyllanthus muellerianus Leaf-Extract on Steel-Reinforcement Corrosion in 3.5% NaCl-Immersed Concrete
Metals 2016, 6(11), 255; doi:10.3390/met6110255
Received: 22 May 2016 / Revised: 4 September 2016 / Accepted: 6 September 2016 / Published: 27 October 2016
Cited by 3 | PDF Full-text (3818 KB) | HTML Full-text | XML Full-text
Abstract
This paper investigates Phyllanthus muellerianus leaf-extract effects on steel-reinforcement corrosion in concrete immersed in 3.5% NaCl, simulating saline/marine environment. Different concentrations of the leaf-extract were admixed in steel-reinforced concrete samples, which were immersed, with normal control, in the test-environment, while positive control samples
[...] Read more.
This paper investigates Phyllanthus muellerianus leaf-extract effects on steel-reinforcement corrosion in concrete immersed in 3.5% NaCl, simulating saline/marine environment. Different concentrations of the leaf-extract were admixed in steel-reinforced concrete samples, which were immersed, with normal control, in the test-environment, while positive control samples were immersed in distilled water. Electrochemical measurements of corrosion-rate (by linear-polarization-resistance instrument), corrosion-current (by zero-resistance-ammeter) and corrosion-potential (by high impedance multimeter) were obtained for assessing the reinforcing-steel corrosion. Analyzed results showed that the corrosion-rate exhibited excellent correlation (R = 98.82%, Nash-Sutcliffe Efficiency = 97.66%, ANOVA p-value = 0.0006) with function of the admixture concentration and of the corrosion noise-resistance (ratio of corrosion-potential and corrosion-current standard deviations). The 0.3333% Phyllanthus muellerianus (per weight of cement) exhibited optimal efficiency, η = 97.58% ± 1.28% (experimental) or 95.33% ± 4.25% (predicted), at inhibiting concrete steel-reinforcement corrosion in the test-environment, which compares well with the positive control performance model, η = 97.96% ± 0.03%. The experimental and predicted models followed the Langmuir adsorption isotherm, which indicated physisorption as the Phyllanthus muellerianus leaf-extract adsorption mechanism on the reinforcing-steel. These support suitability of the N-, S-, and O-containing and π-electron rich Phyllanthus muellerianus leaf-extract as an environmentally-friendly inhibitor for effective corrosion-protection of steel-reinforcement in concrete designed for the saline/marine environment. Full article
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Open AccessFeature PaperArticle Classification of Induced Magnetic Field Signals for the Microstructural Characterization of Sigma Phase in Duplex Stainless Steels
Metals 2016, 6(7), 164; doi:10.3390/met6070164
Received: 7 May 2016 / Revised: 23 June 2016 / Accepted: 7 July 2016 / Published: 14 July 2016
Cited by 5 | PDF Full-text (7151 KB) | HTML Full-text | XML Full-text
Abstract
Duplex stainless steels present excellent mechanical and corrosion resistance properties. However, when heat treated at temperatures above 600 C, the undesirable tertiary sigma phase is formed. This phase presents high hardness, around 900 HV, and it is rich in chromium, the material
[...] Read more.
Duplex stainless steels present excellent mechanical and corrosion resistance properties. However, when heat treated at temperatures above 600 C, the undesirable tertiary sigma phase is formed. This phase presents high hardness, around 900 HV, and it is rich in chromium, the material toughness being compromised when the amount of this phase is not less than 4%. This work aimed to develop a solution for the detection of this phase in duplex stainless steels through the computational classification of induced magnetic field signals. The proposed solution is based on an Optimum Path Forest classifier, which was revealed to be more robust and effective than Bayes, Artificial Neural Network and Support Vector Machine based classifiers. The induced magnetic field was produced by the interaction between an applied external field and the microstructure. Samples of the 2205 duplex stainless steel were thermal aged in order to obtain different amounts of sigma phases (up to 18% in content). The obtained classification results were compared against the ones obtained by Charpy impact energy test, amount of sigma phase, and analysis of the fracture surface by scanning electron microscopy and X-ray diffraction. The proposed solution achieved a classification accuracy superior to 95% and was revealed to be robust to signal noise, being therefore a valid testing tool to be used in this domain. Full article
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Review

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Open AccessReview An Evaluation of Mechanical Properties with the Hardness of Building Steel Structural Members for Reuse by NDT
Metals 2016, 6(10), 247; doi:10.3390/met6100247
Received: 9 June 2016 / Revised: 12 October 2016 / Accepted: 13 October 2016 / Published: 19 October 2016
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Abstract
The reuse system proposed by the authors is one method to reduce the environmental burden in the structural field. As for reusable members, we take up building steel structures used for plants and warehouses. These buildings are assumed to be demolished within approximately
[...] Read more.
The reuse system proposed by the authors is one method to reduce the environmental burden in the structural field. As for reusable members, we take up building steel structures used for plants and warehouses. These buildings are assumed to be demolished within approximately 30 years or more for physical, architectural, economic, or social reasons in Japan. In this paper, the performance of steel structural members of a gable frame is evaluated with a non-destructive test for reuse. First, the flow to estimate mechanical properties of steel structural members such as tensile strength, yield strength, and elongation is shown via a non-destructive test. Next, tensile strength, yield strength, and elongation of steel structural members are estimated, with hardness measured with a portable ultrasonic hardness tester. Finally, the mechanical properties of steel structural members for reuse are estimated based on the proposed flow. Full article
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Open AccessReview Review of Electromagnetic-Based Crack Sensors for Metallic Materials (Recent Research and Future Perspectives)
Metals 2016, 6(8), 172; doi:10.3390/met6080172
Received: 20 May 2016 / Revised: 8 July 2016 / Accepted: 20 July 2016 / Published: 25 July 2016
Cited by 1 | PDF Full-text (16182 KB) | HTML Full-text | XML Full-text
Abstract
Evaluation and non-destructive identification of stress-induced cracks or failures in metals is a vital problem in many sensitive environments, including transportation (steel railway tracks, bridges, car wheels, etc.), power plants (steam generator tubing, etc.) and aerospace transportation (landing gear, aircraft fuselages, etc.). There
[...] Read more.
Evaluation and non-destructive identification of stress-induced cracks or failures in metals is a vital problem in many sensitive environments, including transportation (steel railway tracks, bridges, car wheels, etc.), power plants (steam generator tubing, etc.) and aerospace transportation (landing gear, aircraft fuselages, etc.). There are many traditional non-destructive detection and evaluation techniques; recently, near-field millimeter waves and microwave methods have shown incredible promise for augmenting currently available non-destructive techniques. This article serves as a review of developments made until now on this topic; it provides an overview of microwave scanning techniques for crack detection. This article summarizes the abilities of these methods to identify and evaluate cracks (including describing their different physical properties). These methods include applying filters based on dual-behavior resonators (DBRs), using complementary split-ring resonators (CSRRs) for the perturbation of electric fields, using waveguide probe-loaded CSRRs and using a substrate-integrated-waveguide (SIW) cavity for the detection of sub-millimeter surface and subsurface cracks. Full article
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