Novel Steel Compositions and Processing Technologies

A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Metal Casting, Forming and Heat Treatment".

Deadline for manuscript submissions: closed (30 September 2023) | Viewed by 9791

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Guest Editor
Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia
Interests: thermo-mechanical processing of metal alloys and steel; scanning and transmission electron microscopy; microstructure characterisation; solid state phenomena; phase transformations; mechanical properties testing; microstructure-properties relationships; chemical analysis; mineralogy
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Special Issue Information

Dear Colleagues,

Steel is, was and will always be the most popular material on Earth. Why do we say that? Because together with oxygen (O), silicon (Si) and aluminium (Al), iron (Fe) is the most abundant element in the Earth’s crust. When there is plenty of something, it becomes affordable. Today, this economic effect is a determining factor.

Why so we continue to research steel when so much has already been done? Here are four reasons: (i) climate change: global warming must be controlled; metallurgical industry is amongst the largest CO2 emitters; so, novel metallurgical technologies should guarantee reduced air and water pollution; (ii) energy deficit: fossil fuels will run out; therefore, steel manufacturing should consume minimum energy, preferably electricity generated from renewable sources; (iii) aging infrastructure: modernization and replacement of outdated structures and machinery would be beneficial to carry out using stronger, tougher, lighter and more corrosion resistant materials; these may contribute to a cleaner environment and save energy; (iv) education of young generations: research powers the educational process.

We welcome the following topics in this Special Issue:

  1. Attractive properties at minimum alloying element additions;
  2. Novel element combinations and processing parameters leading to unprecedented microstructural characteristics and property values;
  3. Computer-aided alloy design and process technology development;
  4. Low cost low emission technologies, particularly thin strip casting;
  5. Recently developed technologies, for example, additive manufacturing, powder spray, and laser treatment.

Dr. Andrii Kostryzhev
Guest Editor

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Keywords

  • steel
  • microalloying
  • processing technology
  • microstructure characterization
  • mechanical and functional properties

Published Papers (5 papers)

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Research

14 pages, 6435 KiB  
Article
Role of Precipitates on the Grain Coarsening of 20CrMnTi Gear Steel during Pseudo-Carburizing
by Rui Zhang, Qing Yuan, En Tang, Jiaxuan Mo, Zhicheng Zhang, Haijiang Hu and Guang Xu
Metals 2023, 13(8), 1422; https://doi.org/10.3390/met13081422 - 8 Aug 2023
Cited by 1 | Viewed by 929
Abstract
The carburizing period for tool steel could be significantly shortened by operating at a higher carburizing temperature. However, grain coarsening happens during the carburizing process, and then results in the deteriorated surface properties in 20CrMnTi gear steel, especially at an elevated carburizing temperature. [...] Read more.
The carburizing period for tool steel could be significantly shortened by operating at a higher carburizing temperature. However, grain coarsening happens during the carburizing process, and then results in the deteriorated surface properties in 20CrMnTi gear steel, especially at an elevated carburizing temperature. The relationships between grain coarsening and the precipitates in the developed 20CrMnTi gear steel during pseudo-carburizing were established by microstructure characterization, precipitate analysis and in-situ observation to clarify the coarsening mechanism. The results manifested the Baker–Nutting orientation relationship between the (Ti, Mo)(C, N) particles and the matrix, and then testified to the redissolution and ripening of the (Ti, Mo)(C, N) precipitates pre-formed in the α phase during the carburizing. Coarsening in austenite grain during the carburizing process was mainly caused by the rapid redissolution and ripening of the (Ti, Mo)(C, N) precipitates, although this occurred in a very short pseudo-carburizing time. The area density of the dispersed unripe (Ti, Mo)(C, N) particles markedly decreased from 0.389% in as-hot rolled gear steel to 0.341%, and then from 0.279% in carburized steels at 970 and 980 °C, respectively. Additionally, the redissolution and ripening of the (Ti, Mo)(C, N) precipitates were accelerated by the elevated carburizing temperature of 980 °C, at which time the growing rate in austenite grains was 2.34 μm/min during the prior 1 min (0.79 μm/min during the prior 3 min at 970 °C). The temperature then decreased to 0.003 μm/min in the subsequent carburizing process. The results obtained our current work reflected that the particles with excellent thermal stability should play important roles in the limitation of grain coarsening during the carburizing process. Full article
(This article belongs to the Special Issue Novel Steel Compositions and Processing Technologies)
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12 pages, 4684 KiB  
Article
Influence of Cementite Precipitation on Work Hardening Behavior in Ultrafine Grain Steels Rolled at Room and Cryogenic Temperatures
by Zhoutou Wang, Qing Yuan, Zhicheng Zhang, Qingxiao Zhang and Guang Xu
Metals 2022, 12(11), 1845; https://doi.org/10.3390/met12111845 - 28 Oct 2022
Cited by 5 | Viewed by 1446
Abstract
The work hardening behavior of α + θ UFG steel related to α + θ two phase microstructure is more complicated than that of single-phase materials. Very few studies have been conducted on the work hardening of α + θ UFG steels. Therefore, [...] Read more.
The work hardening behavior of α + θ UFG steel related to α + θ two phase microstructure is more complicated than that of single-phase materials. Very few studies have been conducted on the work hardening of α + θ UFG steels. Therefore, it is necessary to study the correlation between the work hardening and α + θ microstructure. In this study, the work hardening behavior of low-carbon ultrafine grain (UFG) steels with different grain size of ferrite and cementite particles, fabricated by rolling and annealing process, was studied. The α grain size was decreased to 132 ± 11 and 200 ± 19 nm in specimens cryorolled and annealed at 450 and 550 °C, which were smaller than that in specimen cold-rolled and annealed at 550 °C. However, the specimen cryorolled and annealed at 550 °C had a tensile strength of 740.3 MPa, which was lower than that in the other specimens. Results indicate that the work hardening is affected by ferrite and cementite in the UFG steels. The relatively coarse ferrite phase and the large number of fine intragranular cementite particles contribute to better work hardening. The intragranular cementite particles play a significant role in the improvement of work hardening, because the geometrically necessary dislocations are apt to form and store around intragranular cementite particles, while the intergranular cementite particles result in the decreased dislocation accumulation ability of ferrite and impair the strength of grain boundaries and work hardening of ferrite + cementite ultrafine grain steels. Full article
(This article belongs to the Special Issue Novel Steel Compositions and Processing Technologies)
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20 pages, 8686 KiB  
Article
Development of Desirable Fine Ferrite Grain Size and Random Second Phase Dual-Phase Steel Microstructures Using Composition and/or Processing Modifications
by Bharath Bandi, Carl Slater, Didier Farrugia and Claire Davis
Metals 2022, 12(7), 1158; https://doi.org/10.3390/met12071158 - 7 Jul 2022
Cited by 3 | Viewed by 1937
Abstract
Microstructural morphology is known to have a significant impact on the mechanical properties of dual-phase steels. A fine ferrite grain size and random distribution of small second phase islands are desirable to provide superior isotropic properties compared to the banded second phase distribution [...] Read more.
Microstructural morphology is known to have a significant impact on the mechanical properties of dual-phase steels. A fine ferrite grain size and random distribution of small second phase islands are desirable to provide superior isotropic properties compared to the banded second phase distribution that is typical for this type of steel. A rapid alloy prototyping (RAP) facility has been used to investigate three different DP 800 variants by systematically varying the compositions and/or process parameters compared to the ‘standard’ DP800 composition and processing that gives a banded microstructure. For Variant 1, the heating rate during the annealing cycle after cold rolling varied between 0.65 and 30 °C/s for the 45%, 60% and 75% cold reduction samples. It was found that a cold reduction of 75% and heating rate of 15 °C/s resulted in the microstructure that can give the best combination of strength and ductility because of the fine grain size and high martensite volume fraction. For Variant 2, the effect of changing the hot rolled (HR) microstructure (ferrite–pearlite, ferrite–bainite or martensite) on the final microstructure was investigated. Both the ferrite–50% bainite and fully martensite/bainite HR materials for all cold reductions resulted in annealed microstructures with necklace martensite morphology and finer ferrite grains compared to the ferrite–pearlite HR material, which gave a typical banded ferrite–martensite microstructure with a coarser ferrite grain size. For Variant 3, the Mn content was reduced, and increased Nb was used to achieve higher pancaking during the hot rolling stage, which refined ferrite grains in the HR condition with the same hardness. After annealing with the standard parameters only the 45% cold-reduced material produced a finer ferrite grain size than the standard material, whereas the 60% and 75% cold-reduced samples required a higher heating rate to achieve finer ferrite grain sizes due to rapid recrystallisation and growth kinetics. Full article
(This article belongs to the Special Issue Novel Steel Compositions and Processing Technologies)
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13 pages, 23265 KiB  
Article
Effect of Calcium Treatment on Inclusions in H08A Welding Rod Steel
by Fangjie Lan, Changling Zhuang, Changrong Li, Guangkai Yang and Hanjie Yao
Metals 2021, 11(8), 1227; https://doi.org/10.3390/met11081227 - 31 Jul 2021
Cited by 4 | Viewed by 2194
Abstract
The effect of calcium treatment on inclusions in H08A welding rod steel was studied by industrial experiment and using thermodynamics theory. The effects of inclusion composition, morphology, quantity, and size in H08A welding rod steel before and after calcium treatment were studied by [...] Read more.
The effect of calcium treatment on inclusions in H08A welding rod steel was studied by industrial experiment and using thermodynamics theory. The effects of inclusion composition, morphology, quantity, and size in H08A welding rod steel before and after calcium treatment were studied by metallographic microscope, scanning electron microscope (SEM), and energy dispersive spectrometer (EDS). Thermodynamic studies show that the addition of calcium can form various forms of xCaO·yAl2O3, under the condition that the composition of molten steel remains unchanged, the control of calcium content is the key to generate low melting point calcium-aluminate complex non-metallic inclusions and improve the quality of molten steel. The production practice in steel plant shows that for welding rod steels, the calcium content in a suitable range can meet the requirements of calcium treatment. Effective calcium treatment can not only transform the high melting point Al2O3 inclusions into the low melting point complex non-metallic inclusions between 3CaO·Al2O3 and 12CaO·7Al2O3, but also make the original shape-diversified inclusions into the spherical calcium-aluminate complex non-metallic inclusions. Meanwhile, the total number of inclusions and large-scale inclusions in welding rod steel are reduced, and the inclusions tend to disperse in the steel, which is very conducive to the improvement of steel quality. The results show that the modification path of magnesium aluminate spinel in steel is as follows: Al2O3 → MgO-Al2O3 → MgO-CaO-Al2O3. In addition, calcium treatment can modify MgO-Al2O3 spinel in steel into liquid MgO-CaO-Al2O3 complex non-metallic inclusions with low melting point. Full article
(This article belongs to the Special Issue Novel Steel Compositions and Processing Technologies)
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14 pages, 5573 KiB  
Article
Effect of Processing Parameters on Interphase Precipitation and Mechanical Properties in Novel CrVNb Microalloyed Steel
by Andrii Kostryzhev, Chris Killmore and Elena Pereloma
Metals 2021, 11(1), 107; https://doi.org/10.3390/met11010107 - 7 Jan 2021
Cited by 3 | Viewed by 2174
Abstract
Novel steel microalloyed with 0.73 (Cr + V + Nb) has been subjected to thermomechanical processing (TMP) with varying parameters to simultaneously maximise the steel strength and ductility. Optical and electron microscopy studies coupled with uniaxial tensile testing were carried out to analyse [...] Read more.
Novel steel microalloyed with 0.73 (Cr + V + Nb) has been subjected to thermomechanical processing (TMP) with varying parameters to simultaneously maximise the steel strength and ductility. Optical and electron microscopy studies coupled with uniaxial tensile testing were carried out to analyse the processing-microstructure-properties relationship. For the suggested steel composition, the simultaneously highest yield stress (960 MPa), ultimate tensile strength (1100 MPa), and elongation to failure (25%) were achieved following simulated coiling at 650 °C and holding for 30 min. The variation in the finish rolling temperature affects the ferrite grain size and the ratio of precipitates formed in austenite and ferrite. If a significant amount of solute is consumed for precipitation in austenite and during subsequent growth of strain-induced precipitates, then a lower fraction of interphase and random precipitates forms in ferrite resulting in a lower strength. Extended time at a simulated coiling temperature resulted in the growth of interphase precipitates and precipitation of random ones in ferrite. Fine tuning of TMP parameters is required to maximise the contribution to strength arising from different microstructural features. Full article
(This article belongs to the Special Issue Novel Steel Compositions and Processing Technologies)
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