Special Issue "High-Strength Low-Alloy Steels"

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

Deadline for manuscript submissions: 31 May 2019

Special Issue Editors

Guest Editor
Prof. Ricardo Branco

University of Coimbra, Centre for Mechanical Engineering, Materials and Processes, Coimbra, Portugal
Website | E-Mail
Interests: mechanical behavior of materials; fatigue and fracture; multiaxial fatigue; low-cycle fatigue; fatigue crack initiation
Guest Editor
Prof. Dr. Filippo Berto

Department of Industrial and Mechanical Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway
Website | E-Mail
Phone: +4748500574
Interests: fatigue of advanced and traditional materials; fracture mechanics; solid mechanics; structural integrity; additive materials

Special Issue Information

Dear Colleagues,

High-strength low-alloy steels are designed to provide specific desirable combinations of properties, such as strength, toughness, formability, weldability, and corrosion resistance. These features make them ideal for critical applications that operate under severe service conditions and in aggressive environments, namely automotive and aeronautical components, offshore and bridge structures, construction machinery and pipelines, to mention just a few.  Despite the huge progress achieved over time on the behaviour of high-strength low-alloy steels, the development of more sophisticated products, combined with new manufacturing methodologies and new processing techniques, require additional research to address the new unsolved questions and to strengthen the existing knowledge in the field.

The goal of this Special Issue is to foster the dissemination of the latest research devoted to high-strength low-alloy steels from different perspectives, more specifically: the assessment of structural integrity, experimental analysis and numerical modelling of mechanical behaviour, damage and failure under static and dynamic loading, alloy design and microstructural evaluation, the influence of environmental mediums, and advanced applications. Both experimental and numerical approaches are encouraged. Literature review articles are also welcome.

Prof. Ricardo Branco
Prof. Filippo Berto
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 1500 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

  • High-strength steels
  • Manufacturing and processing techniques
  • Alloy design
  • Microstructure and texture
  • Loading history
  • Environmental conditions
  • Advanced applications

Published Papers (5 papers)

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Research

Open AccessArticle Mechanical Properties of Direct-Quenched Ultra-High-Strength Steel Alloyed with Molybdenum and Niobium
Metals 2019, 9(3), 350; https://doi.org/10.3390/met9030350
Received: 6 March 2019 / Revised: 14 March 2019 / Accepted: 16 March 2019 / Published: 19 March 2019
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Abstract
The direct quenching process is an energy- and resource-efficient process for making high-strength structural steels with good toughness, weldability, and bendability. This paper presents the results of an investigation into the effect of molybdenum and niobium on the microstructures and mechanical properties of [...] Read more.
The direct quenching process is an energy- and resource-efficient process for making high-strength structural steels with good toughness, weldability, and bendability. This paper presents the results of an investigation into the effect of molybdenum and niobium on the microstructures and mechanical properties of laboratory rolled and direct-quenched 11 mm thick steel plates containing 0.16 wt.% C. Three of the studied compositions were niobium-free, having molybdenum contents of 0 wt.%, 0.25 wt.%, and 0.5 wt.%. In addition, a composition containing 0.25 wt.% molybdenum and 0.04 wt.% niobium was studied. Prior to direct quenching, finish rolling temperatures (FRTs) of about 800 °C and 900 °C were used to obtain different levels of austenite pancaking. The final direct-quenched microstructures were martensitic and yield strengths varied in the range of 766–1119 MPa. Mo and Nb additions led to a refined martensitic microstructure that resulted in a good combination of strength and toughness. Furthermore, Mo and Nb alloying significantly reduced the amount of strain-induced ferrite in the microstructure at lower FRTs (800 °C). The steel with 0.5 wt.% Mo exhibited a high yield strength of 1119 MPa combined with very low 28 J transition temperature of −95 °C in the as-quenched condition. Improved mechanical properties of Mo and Mo–Nb steels can be attributed to the improved boron protection. Also, the crystallographic texture of the investigated steels showed that Nb and Nb–Mo alloying increased the amount of {112}<131> and {554}<225> texture components. The 0Mo steel also contained the texture components of {110}<110> and {011}<100>, which can be considered to be detrimental for impact toughness properties. Full article
(This article belongs to the Special Issue High-Strength Low-Alloy Steels)
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Open AccessFeature PaperArticle Influence of Mechanical Anisotropy on Micro-Voids and Ductile Fracture Onset and Evolution in High-Strength Low Alloyed Steels
Metals 2019, 9(2), 224; https://doi.org/10.3390/met9020224
Received: 20 December 2018 / Revised: 4 February 2019 / Accepted: 12 February 2019 / Published: 13 February 2019
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Abstract
In this paper results of a wide and innovative mechanical assessment, that was performed on large diameter spiral line pipes for gas transportation, are reported. The anisotropic material hardening has been characterized by tensile (smooth and notched specimens), torsion, and compression tests. Tests [...] Read more.
In this paper results of a wide and innovative mechanical assessment, that was performed on large diameter spiral line pipes for gas transportation, are reported. The anisotropic material hardening has been characterized by tensile (smooth and notched specimens), torsion, and compression tests. Tests were performed in the pipe of the pipe with specimens machined along several orientations, taking into account the pipe through thickness direction. The influence of different triaxiality stress states on anisotropic behavior of the material have also been analyzed by means of tensile tests on notched specimens. After the experiments, the material was assessed by measuring the void distribution on the material as is, and on many deformed and fractured specimens, including tensile tests at different triaxiality, and torsion tests. The results showed that in such a class of materials, the experimental void fraction is fully negligible and not related to the applied plastic strain, even at the fracture proximity. As a consequence it can be concluded that, the plastic softening hypothesis may be dropped and damage due to void evolution hypothesis is not adequate. Full article
(This article belongs to the Special Issue High-Strength Low-Alloy Steels)
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Open AccessArticle Modelling and Microstructural Aspects of Ultra-Thin Sheet Metal Bundle Cutting
Metals 2019, 9(2), 162; https://doi.org/10.3390/met9020162
Received: 31 December 2018 / Revised: 23 January 2019 / Accepted: 29 January 2019 / Published: 1 February 2019
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Abstract
The results of numerical simulations of the cutting process obtained by means of the finite element method were studied in this work. The physical model of a bundle consisting of ultra-thin metal sheets was elaborated and then submitted to numerical calculations using the [...] Read more.
The results of numerical simulations of the cutting process obtained by means of the finite element method were studied in this work. The physical model of a bundle consisting of ultra-thin metal sheets was elaborated and then submitted to numerical calculations using the computer system LS-DYNA. Experimental investigations rely on observation of metallographic specimens of the surfaces being cut under a scanning electron microscope. The experimental data showing the microstructure of an ultra-thin metal bundle were the basis for the verification of the numerical results. It was found that the fracture area consists of two distinct zones. Morphological features of the brittle and ductile zones were identified. There are distinct differences between the front and back sides of the knife. The experimental investigations are in good agreement with the simulation results. Full article
(This article belongs to the Special Issue High-Strength Low-Alloy Steels)
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Open AccessArticle Multiaxial Fatigue Life Prediction on S355 Structural and Offshore Steel Using the SKS Critical Plane Model
Metals 2018, 8(12), 1060; https://doi.org/10.3390/met8121060
Received: 13 November 2018 / Revised: 5 December 2018 / Accepted: 6 December 2018 / Published: 13 December 2018
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Abstract
This work analyses the prediction capabilities of a recently developed critical plane model, called the SKS method. The study uses multiaxial fatigue data for S355-J2G3 steel, with in-phase and 90° out-of-phase sinusoidal axial-torsional straining in both the low cycle fatigue and high cycle [...] Read more.
This work analyses the prediction capabilities of a recently developed critical plane model, called the SKS method. The study uses multiaxial fatigue data for S355-J2G3 steel, with in-phase and 90° out-of-phase sinusoidal axial-torsional straining in both the low cycle fatigue and high cycle fatigue ranges. The SKS damage parameter includes the effect of hardening, mean shear stress and the interaction between shear and normal stress on the critical plane. The collapse and the prediction capabilities of the SKS critical plane damage parameter are compared to well-established critical plane models, namely Wang-Brown, Fatemi-Socie, Liu I and Liu II models. The differences between models are discussed in detail from the basis of the methodology and the life results. The collapse capacity of the SKS damage parameter presents the best results. The SKS model produced the second-best results for the different types of multiaxial loads studied. Full article
(This article belongs to the Special Issue High-Strength Low-Alloy Steels)
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Open AccessArticle Austenite Decomposition and Precipitation Behavior of Plastically Deformed Low-Si Microalloyed Steel
Metals 2018, 8(12), 1028; https://doi.org/10.3390/met8121028
Received: 21 November 2018 / Revised: 2 December 2018 / Accepted: 3 December 2018 / Published: 6 December 2018
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Abstract
The aim of the present study is to assess the effects of hot deformation and cooling paths on the phase transformation kinetics in a precipitation-strengthened automotive 0.2C–1.5Mn–0.5Si steel with Nb and Ti microadditions. The analysis of the precipitation processes was performed while taking [...] Read more.
The aim of the present study is to assess the effects of hot deformation and cooling paths on the phase transformation kinetics in a precipitation-strengthened automotive 0.2C–1.5Mn–0.5Si steel with Nb and Ti microadditions. The analysis of the precipitation processes was performed while taking into account equilibrium calculations and phase transitions resulting from calculated time–temperature–transformation (TTT) and continuous cooling transformation (CCT) diagrams. The austenite decomposition was monitored based on thermodynamic calculations of the volume fraction evolution of individual phases as a function of temperature. The calculations were compared to real CCT and DCCT (deformation continuous cooling transformation) diagrams produced using dilatometric tests. The research included the identification of the microstructure of the nondeformed and thermomechanically processed supercooled austenite products formed at various cooling rates. The complex interactions between the precipitation process, hot deformation, and cooling schedules are linked. Full article
(This article belongs to the Special Issue High-Strength Low-Alloy Steels)
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