Special Issue "Advances in Microalloyed Steels"

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

Deadline for manuscript submissions: 31 July 2018

Special Issue Editor

Guest Editor
Assoc. Prof. Pello Uranga

1. Associate Director of the Materials and Manufacturing Division at CEIT
2. Associate Professor at Tecnun-School of Engineering (Univ. of Navarra). CEIT and Tecnun (University of Navarra), M. Lardizabal 15, 20018 Donostia-San Sebastian, Basque Country, Spain
Website | E-Mail
Interests: Phase Transformations; Microstructure; Microscopy; Microalloying; Steels; Metallurgy; Materials Science; Modelling

Special Issue Information

Dear Colleagues,

In response to the demanding requirements of different sectors, such as construction, transportation, energy, manufacturing, and mining, new generations of microalloyed steels are being developed and brought to market. The addition of microalloying elements, such as Niobium, Vanadium, Titanium, Boron and/or Molybdenum have become a key tool in the steel industry to reach economically-viable grades with increasingly higher mechanical strengths, toughness properties, good formability and weldable products.

The challenges that microalloying steel production face can be successfully solved with a deeper understanding of the effects that these microalloying additions and combinations of them have during the different steps of the steelmaking process. Their influence in softening mechanisms, such as recrystallization and grain growth during hot working, precipitation kinetics, phase transformation during cooling, and the relationship between the final microstructure and mechanical properties are just some examples of subjects of interest for research in industry and academia.

The availability of advanced characterization techniques together with innovative modelling strategies provides new tools to understand these open issues and achieve valid answers for the development of new microalloyed grades and the optimization of the processing routes.

For this Special Issue on "Advances in Microalloyed Steels", I would like to invite researchers from steel industry and academia to submit their latest developments and achievements in this field.

Assoc. Prof. Pello Uranga
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

  • Niobium
  • Vanadium
  • Titanium
  • Boron
  • Molybdenum
  • Thermomechanical Processing
  • Phase Transformations
  • Microstructure
  • Mechanical Properties
  • Modelling

Published Papers (5 papers)

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Research

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Open AccessArticle Physically-Based Modeling and Characterization of Hot Flow Behavior in an Interphase-Precipitated Ti-Mo Microalloyed Steel
Metals 2018, 8(4), 243; https://doi.org/10.3390/met8040243
Received: 21 March 2018 / Revised: 1 April 2018 / Accepted: 3 April 2018 / Published: 6 April 2018
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Abstract
In this contribution, a series of hot compression tests was conducted on a typical interphase-precipitated Ti-Mo steel at relatively higher strain rates of 0.1~10 s−1 and temperatures of 900~1150 °C using a Gleeble-2000 thermo-mechanical simulator. A combination of Bergstrom and Kolmogorov–Johnson–Mehl–Avrami models
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In this contribution, a series of hot compression tests was conducted on a typical interphase-precipitated Ti-Mo steel at relatively higher strain rates of 0.1~10 s−1 and temperatures of 900~1150 °C using a Gleeble-2000 thermo-mechanical simulator. A combination of Bergstrom and Kolmogorov–Johnson–Mehl–Avrami models was first used to accurately predict the whole flow behaviors of Ti-Mo steel involving dynamic recrystallization, under various hot deformation conditions. By comparing the characteristic stresses and material parameters, especially at the higher strain rates studied, the dependence of hot flow behavior on strain rate and deformation temperature was further clarified. The hardening parameter U and peak density ρp exhibited an approximately positive linear relationship with the Zener–Hollomon (Z) parameter, while the softening parameter Ω dropped with increasing Z value. The Avrami exponent nA varied between 1.2 and 2.1 with lnZ, implying two diverse nucleation mechanisms of dynamic recrystallization. The experimental verification was performed as well based on the microstructural evolution and mechanism analysis upon straining. The proposed constitutive models may provide a powerful tool for optimizing the hot working processes of high performance Ti-Mo microalloyed steels with interphase precipitation. Full article
(This article belongs to the Special Issue Advances in Microalloyed Steels)
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Open AccessArticle Comparative Effect of Mo and Cr on Microstructure and Mechanical Properties in NbV-Microalloyed Bainitic Steels
Metals 2018, 8(2), 134; https://doi.org/10.3390/met8020134
Received: 4 January 2018 / Revised: 10 February 2018 / Accepted: 13 February 2018 / Published: 16 February 2018
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Abstract
Steel product markets require the rolled stock with further increasing mechanical properties and simultaneously decreasing price. The steel cost can be reduced via decreasing the microalloying elements contents, although this decrease may undermine the mechanical properties. Multi-element microalloying with minor additions is the
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Steel product markets require the rolled stock with further increasing mechanical properties and simultaneously decreasing price. The steel cost can be reduced via decreasing the microalloying elements contents, although this decrease may undermine the mechanical properties. Multi-element microalloying with minor additions is the route to optimise steel composition and keep the properties high. However, this requires deep understanding of mutual effects of elements on each other’s performance with respect to the development of microstructure and mechanical properties. This knowledge is insufficient at the moment. In the present work we investigate the microstructure and mechanical properties of bainitic steels microalloyed with Cr, Mo, Nb and V. Comparison of 0.2 wt. % Mo and Cr additions has shown a more pronounced effect of Mo on precipitation than on phase balance. Superior strength of the MoNbV-steel originated from the strong solid solution strengthening effect. Superior ductility of the CrNbV-steel corresponded to the more pronounced precipitation in this steel. Nature of these mechanisms is discussed. Full article
(This article belongs to the Special Issue Advances in Microalloyed Steels)
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Open AccessArticle The Influence of La and Ce Addition on Inclusion Modification in Cast Niobium Microalloyed Steels
Metals 2017, 7(9), 377; https://doi.org/10.3390/met7090377
Received: 7 August 2017 / Revised: 28 August 2017 / Accepted: 29 August 2017 / Published: 15 September 2017
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Abstract
The main role of Rare Earth (RE) elements in the steelmaking industry is to affect the nature of inclusions (composition, geometry, size and volume fraction), which can potentially lead to the improvement of some mechanical properties such as the toughness in steels. In
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The main role of Rare Earth (RE) elements in the steelmaking industry is to affect the nature of inclusions (composition, geometry, size and volume fraction), which can potentially lead to the improvement of some mechanical properties such as the toughness in steels. In this study, different amounts of RE were added to a niobium microalloyed steel in as-cast condition to investigate its influence on: (i) type of inclusions and (ii) precipitation of niobium carbides. The characterization of the microstructure by optical, scanning and transmission electron microscopy shows that: (1) the addition of RE elements change the inclusion formation route during solidification; RE > 200 ppm promote formation of complex inclusions with a (La,Ce)(S,O) matrix instead of Al2O3-MnS inclusions; (2) the roundness of inclusions increases with RE, whereas more than 200 ppm addition would increase the area fraction and size of the inclusions; (3) it was found that the presence of MnS in the base and low RE-added steel provide nucleation sites for the precipitation of coarse niobium carbides and/or carbonitrides at the matrix–MnS interface. Thermodynamic calculations show that temperatures of the order of 1200 °C would be necessary to dissolve these coarse Nb-rich carbides so as to reprecipitate them as nanoparticles in the matrix. Full article
(This article belongs to the Special Issue Advances in Microalloyed Steels)
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Review

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Open AccessReview Microalloyed Steels through History until 2018: Review of Chemical Composition, Processing and Hydrogen Service
Metals 2018, 8(5), 351; https://doi.org/10.3390/met8050351
Received: 22 March 2018 / Revised: 20 April 2018 / Accepted: 25 April 2018 / Published: 14 May 2018
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Abstract
Microalloyed steels have evolved in terms of their chemical composition, processing, and metallurgical characteristics since the beginning of the 20th century in the function of fabrication costs and mechanical properties required to obtain high-performance materials needed to accommodate for the growing demands of
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Microalloyed steels have evolved in terms of their chemical composition, processing, and metallurgical characteristics since the beginning of the 20th century in the function of fabrication costs and mechanical properties required to obtain high-performance materials needed to accommodate for the growing demands of gas and hydrocarbons transport. As a result of this, microalloyed steels present a good combination of high strength and ductility obtained through the addition of microalloying elements, thermomechanical processing, and controlled cooling, processes capable of producing complex microstructures that improve the mechanical properties of steels. These controlled microstructures can be severely affected and result in catastrophic failures, due to the atomic hydrogen diffusion that occurs during the corrosion process of pipeline steel. Recently, a martensite–bainite microstructure with acicular ferrite has been chosen as a viable candidate to be used in environments with the presence of hydrogen. The aim of this review is to summarize the main changes of chemical composition, processing techniques, and the evolution of the mechanical properties throughout recent history on the use of microalloying in high strength low alloy steels, as well as the effects of hydrogen in newly created pipelines, examining the causes behind the mechanisms of hydrogen embrittlement in these steels. Full article
(This article belongs to the Special Issue Advances in Microalloyed Steels)
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Open AccessReview Property Optimization in As-Quenched Martensitic Steel by Molybdenum and Niobium Alloying
Metals 2018, 8(4), 234; https://doi.org/10.3390/met8040234
Received: 8 February 2018 / Revised: 21 March 2018 / Accepted: 28 March 2018 / Published: 3 April 2018
Cited by 1 | PDF Full-text (26796 KB) | HTML Full-text | XML Full-text
Abstract
Niobium microalloying is the backbone of modern low-carbon high strength low alloy (HSLA) steel metallurgy, providing a favorable combination of strength and toughness by pronounced microstructural refinement. Molybdenum alloying is established in medium-carbon quenching and tempering of steel by delivering high hardenability and
[...] Read more.
Niobium microalloying is the backbone of modern low-carbon high strength low alloy (HSLA) steel metallurgy, providing a favorable combination of strength and toughness by pronounced microstructural refinement. Molybdenum alloying is established in medium-carbon quenching and tempering of steel by delivering high hardenability and good tempering resistance. Recent developments of ultra-high strength steel grades, such as fully martensitic steel, can be optimized by using beneficial metallurgical effects of niobium and molybdenum. The paper details the metallurgical principles of both elements in such steel and the achievable improvement of properties. Particularly, the underlying mechanisms of improving toughness and reducing the sensitivity towards hydrogen embrittlement by a suitable combination of molybdenum and niobium alloying will be discussed. Full article
(This article belongs to the Special Issue Advances in Microalloyed Steels)
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