Special Issue "Microalloyed Steel"

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

Deadline for manuscript submissions: closed (31 March 2016)

Special Issue Editor

Guest Editor
Prof. Dr. Isabel Gutierrez

CEIT and Tecnun (University of Navarra), Manuel de Lardizábal 15, 20018 Donostia-San Sebastián, Spain
Website | E-Mail
Interests: recrystallization, precipitation, phase transformation, thermomechanical processing of steels, cold rolling and annealing, relations between microstructure and mechanical properties

Special Issue Information

Dear Colleagues,

Microalloying in steels is about a century old. The attractiveness of microalloying is that it allows the reduction of costs by suppressing heat treatments and improving strength, weldability (reduction of C and Mn), and toughness (grain refinement). The use of Nb, V, and Ti, either as single micro-additions or in combination, together with thermomechanical processing and accelerated cooling, has been the base for the development of high strength low alloy (HSLA) steels. It can be estimated that these steels now represent 10% to 15% of the world’s steel production.

The progressive development of HSLA steels has been accompanied by intensive research providing the required metallurgical support. As a result, numerous international conferences have been entirely dedicated to this particular type of steel, and countless reviews and journal papers have been published in this field. Nevertheless, the subject remains of interest and is faced with both old and new challenges, such as:

  • The need for improved microstructural homogeneity and combination of properties: strength, weldability, and toughness of the base material and at the HAZ.
  • Close control of additions and use of tailored combinations of microalloying elements, adapted specifically to the plant conditions and product format.
  • Optimized adaptation to more recent production technologies, such as near net shape and direct rolling, and the production of high strength high gauge sheets and sections.

Microalloying is also applied in advanced high strength steels (AHSS), such as dual phase (DP) and transformation induced plasticity (TRIP) steels, in martensitic plates and sheets (ultrahigh strength steels (UHSS)), and in engineering steels. The challenges are driven by the same general idea of acquiring improved material performance at a minimum cost.

Papers on recent advances and review articles, particularly related to the most challenging aspects of the use of microalloying, are invited for inclusion in this Special Issue on "Microalloyed steels".

Prof. Dr. Isabel Gutierrez
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 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

  • Casting
  • Near net shape
  • TMCP (Thermomechanical processing)
  • Annealing after cold rolling
  • Thermal treatment
  • Solution and precipitation
  • Austenite conditioning
  • Phase transformation
  • Recrystallization
  • Texture
  • Material performance
  • Modelling

Published Papers (5 papers)

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Research

Open AccessArticle Vanadium Effect on a Medium Carbon Forging Steel
Metals 2016, 6(6), 130; doi:10.3390/met6060130
Received: 29 March 2016 / Revised: 22 May 2016 / Accepted: 26 May 2016 / Published: 30 May 2016
Cited by 3 | PDF Full-text (6803 KB) | HTML Full-text | XML Full-text
Abstract
In the present work the influence of vanadium on the hardenability and the bainitic transformation of a medium carbon steel is analyzed. While V in solid solution enhances the former, it hardly affects bainitic transformation. The results also reveal an unexpected result, an
[...] Read more.
In the present work the influence of vanadium on the hardenability and the bainitic transformation of a medium carbon steel is analyzed. While V in solid solution enhances the former, it hardly affects bainitic transformation. The results also reveal an unexpected result, an increase of the prior austenite grain size as the V content increases. Full article
(This article belongs to the Special Issue Microalloyed Steel)
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Open AccessArticle Tensile Fracture Behavior of Progressively-Drawn Pearlitic Steels
Metals 2016, 6(5), 114; doi:10.3390/met6050114
Received: 31 March 2016 / Revised: 8 May 2016 / Accepted: 10 May 2016 / Published: 17 May 2016
Cited by 4 | PDF Full-text (11390 KB) | HTML Full-text | XML Full-text
Abstract
In this paper a study is presented of the tensile fracture behavior of progressively-drawn pearlitic steels obtained from five different cold-drawing chains, including each drawing step from the initial hot-rolled bar (not cold-drawn at all) to the final commercial product (pre-stressing steel wire).
[...] Read more.
In this paper a study is presented of the tensile fracture behavior of progressively-drawn pearlitic steels obtained from five different cold-drawing chains, including each drawing step from the initial hot-rolled bar (not cold-drawn at all) to the final commercial product (pre-stressing steel wire). To this end, samples of the different wires were tested up to fracture by means of standard tension tests, and later, all of the fracture surfaces were analyzed by scanning electron microscopy (SEM). Micro-fracture maps (MFMs) were assembled to characterize the different fractographic modes and to study their evolution with the level of cumulative plastic strain during cold drawing. Full article
(This article belongs to the Special Issue Microalloyed Steel)
Open AccessArticle Monotonic and Cyclic Behavior of DIN 34CrNiMo6 Tempered Alloy Steel
Metals 2016, 6(5), 98; doi:10.3390/met6050098
Received: 29 March 2016 / Revised: 18 April 2016 / Accepted: 21 April 2016 / Published: 26 April 2016
Cited by 4 | PDF Full-text (8451 KB) | HTML Full-text | XML Full-text
Abstract
This paper aims at studying the monotonic and cyclic plastic deformation behavior of DIN 34CrNiMo6 high strength steel. Monotonic and low-cycle fatigue tests are conducted in ambient air, at room temperature, using standard 8-mm diameter specimens. The former tests are carried out under
[...] Read more.
This paper aims at studying the monotonic and cyclic plastic deformation behavior of DIN 34CrNiMo6 high strength steel. Monotonic and low-cycle fatigue tests are conducted in ambient air, at room temperature, using standard 8-mm diameter specimens. The former tests are carried out under position control with constant displacement rate. The latter are performed under fully-reversed strain-controlled conditions, using the single-step test method, with strain amplitudes lying between ±0.4% and ±2.0%. After the tests, the fracture surfaces are examined by scanning electron microscopy in order to characterize the surface morphologies and identify the main failure mechanisms. Regardless of the strain amplitude, a softening behavior was observed throughout the entire life. Total strain energy density, defined as the sum of both tensile elastic and plastic strain energies, was revealed to be an adequate fatigue damage parameter for short and long lives. Full article
(This article belongs to the Special Issue Microalloyed Steel)
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Open AccessArticle Characterization of Precipitates in a Microalloyed Steel Using Quantitative X-ray Diffraction
Metals 2016, 6(4), 90; doi:10.3390/met6040090
Received: 29 February 2016 / Revised: 29 March 2016 / Accepted: 8 April 2016 / Published: 19 April 2016
Cited by 1 | PDF Full-text (2564 KB) | HTML Full-text | XML Full-text
Abstract
Quantitative X-ray diffraction (QXRD) (also known as the Rietveld method) was used to analyze the precipitates present in Grade 100 microalloyed steel. The precipitates were extracted from the steel using electrolytic dissolution and the residue from the dissolution was analyzed using XRD. The
[...] Read more.
Quantitative X-ray diffraction (QXRD) (also known as the Rietveld method) was used to analyze the precipitates present in Grade 100 microalloyed steel. The precipitates were extracted from the steel using electrolytic dissolution and the residue from the dissolution was analyzed using XRD. The XRD pattern exhibited three (3) distinct diffraction peaks, and significant broadening of a fourth peak corresponding to the <10 nm size precipitates. QXRD analysis was applied to the XRD pattern to obtain precipitate size, composition, and weight fraction data for each of the four diffraction peaks observed. The predicted mean precipitate diameter and average atomic composition of the nano-size (<10 nm) precipitates was 4.7 nm and (Nb0.50Ti0.32Mo0.18)(C0.59N0.41), respectively. The predicted precipitate size correlates well with the average size of precipitates measured in previous work by the authors using both transmission electron microscopy (TEM) and small angle neutron scattering (SANS). The average atomic composition correlates well with the composition measured in this work using energy dispersive X-ray (EDX) analysis of individual nano-sized precipitates. The calculated weight fraction of the nano-size precipitates in the extracted residue was 42.2 wt. %. The calculated atomic compositions of the other three diffraction peaks were TiN, (Ti0.87Nb0.13)N, and (Nb0.82Ti0.18)(C0.87N0.13) with weight fraction values of 12.9 wt. %, 31.7 wt. %, and 13.1 wt. %, respectively. The sizes of both the (Ti0.87Nb0.13)N and the (Nb0.82Ti0.18)(C0.87N0.13) groups of precipitates were directly measured and were observed to range from 150 nm to 570 nm and from 90 nm to 475 nm, respectively. QXRD was unable to determine a reasonable mean precipitate size for either of these two groups of precipitates. The wide compositional range (i.e., varying levels of Nb and Ti) of these precipitates (as measured by EDX) resulted in XRD peak broadening that was erroneously interpreted as a size broadening effect. Full article
(This article belongs to the Special Issue Microalloyed Steel)
Open AccessArticle The Effect of Nb on the Continuous Cooling Transformation Curves of Ultra-Thin Strip CASTRIP© Steels
Metals 2015, 5(4), 1857-1877; doi:10.3390/met5041857
Received: 3 September 2015 / Revised: 18 September 2015 / Accepted: 25 September 2015 / Published: 9 October 2015
Cited by 2 | PDF Full-text (2254 KB) | HTML Full-text | XML Full-text
Abstract
The effect of Nb on the hardenability of ultra-thin cast strip (UCS) steels produced via the unique regime of rapid solidification, large austenite grain size, and inclusion engineering of the CASTRIP© process was investigated. Continuous cooling transformation (CCT) diagrams were constructed for
[...] Read more.
The effect of Nb on the hardenability of ultra-thin cast strip (UCS) steels produced via the unique regime of rapid solidification, large austenite grain size, and inclusion engineering of the CASTRIP© process was investigated. Continuous cooling transformation (CCT) diagrams were constructed for 0, 0.014, 0.024, 0.04, 0.06 and 0.08 wt% Nb containing UCS steels. Phase nomenclature for the identification of lower transformation product in low carbon steels was reviewed. Even a small addition of 0.014 wt% Nb showed a potent effect on hardenability, shifting the ferrite C-curve to the right and expanding the bainitic ferrite and acicular ferrite phase fields. Higher Nb additions increased hardenability further, suppressed the formation of ferrite to even lower cooling rates, progressively lowered the transformation start and finish temperatures and promoted the transformation of bainite instead of acicular ferrite. The latter was due to Nb suppressing the formation of allotriomorphic ferrite and allowing bainite to nucleate at prior austenite grain boundaries, a lower energy site than that for the intragranular nucleation of acicular ferrite at inclusions. Strength and hardness increased with increasing Nb additions, largely due to microstructural strengthening and solid solution hardening, but not from precipitation hardening. Full article
(This article belongs to the Special Issue Microalloyed Steel)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Precipitate Characterization of a Microalloyed Steel Using Quantitative X-Ray Diffraction (Rietveld Method)
Authors: J.B. Wiskel 1, J. Lu 2, O. Omotoso 3, D.G. Ivey 1 and H. Henein 1
Affiliation:
1. Dept. of Chem. and Mat. Eng., University of Alberta, Edmonton, Alberta, Canada, T6G 2V4
2. Enbridge Pipelines, 10201, Jasper Ave, Edmonton, Alberta, Canada, T5J 3N7
3. Suncor Energy, W23-100, Suncor Energy Centre, Calgary, Alberta, Canada, T2P 3E3
Abstract: Quantitative X-ray diffraction (Rietveld method) was used to analyze the precipitates present in Grade 100 microalloyed steel. The precipitates were extracted from the steel using electrolytic dissolution and the residue from the dissolution was analyzed using X-ray diffraction. The diffraction pattern obtained from the extracted precipitates exhibited three (3) distinct peaks, and significant broadening of a fourth peak (corresponding to the < 10 nm size particles). The Rietveld method was applied to the measured diffraction pattern to obtain precipitate size, composition and weight fraction data for each peak. The mean precipitate diameter and average atomic composition of the nano-size (< 10 nm) precipitates was 4.7 nm and (Nb0.50Ti0.32Mo0.18) (C0.59N0.41) respectively. This precipitate size correlates well with the precipitate sizes measured in previous work by the authours using TEM and SANS. The average precipitate composition correlates well with the composition measured using energy dispersive x-ray analysis (in a TEM) for individual nano-sized precipitates. The calculated weight fraction of the nano-size precipitates in the extracted residue was 42.2wt%. The atomic compositions associated with the three distinct peaks observed in the X-ray diffraction pattern were calculated to be TiN, (Ti0.87Nb0.13)N and (Nb0.82Ti0.18)(C0.87N0.13) with weight fraction values of 12.9wt%, 31.7wt% and 13.1wt% respectively. The sizes of both the (Ti0.87Nb0.13)N group and the (Nb0.82Ti0.18)(C0.87N0.13) group were directly measured (in the TEM) and were observed to range from 150 nm to 570 nm and from 90 nm to 475 nm respectively. The Rietveld method was unable to determine a reasonable mean precipitate size for these two groups of precipitates. The compositional diversity of the precipitates (centered on the most common composition) resulted in X-ray diffraction peak broadening which was erroneously interpreted as a size broadening effect. The results from this work show that quantitative X-ray diffraction can be used to quantify some precipitate characteristics (i.e., weight fraction, the most prevalent precipitate composition and the size of the nano precipitates) in microalloyed steels.

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