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Thermomechanical Treatment of Metals and Alloys
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Thermomechanical Treatment of Metals and Alloys

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 June 2023) | Viewed by 29437

Special Issue Editor

Dr. Igor Yu. Litovchenko

E-Mail Website
Guest Editor
Institute of Strength Physics and Materials Science of the Siberian Branch of the Russian Academy of Sciences, 634055 Tomsk, Russia
Interests: steels; in-core nuclear power engineering materials; plastic deformation; thermomechanical treatment; phase transformations, deformation-induced martensite; austenite reversion; precipitation, electron microscopy; deformation microstructures; grain refinement; mechanical properties
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Thermomechanical treatments are among the most effective methods for modifying the grain structure, structural phase states, and defect substructure determining the mechanical properties of metals and alloys. The development of new alloys and the use of new processing types open up prospects for achieving a unique combination of strength, plasticity, and functional properties in metallic materials. Despite the numerous studies along this line, the role of thermomechanical treatments in ensuring the required level of mechanical properties, the issues of the strengthening mechanisms, and the possibility of increasing strength via new grain-boundary and structural-phase designs are still open.

This Special Issue addresses the effect of various thermomechanical treatments on structural phase states, deformed microstructure, and mechanical properties of a wide range of metallic materials, including pure metals, steels, and alloys. Your articles considering the role of strengthening mechanisms (solid solution, grain boundary, substructural, dispersion, etc.) in ensuring the mechanical properties of metals and alloys under any thermomechanical treatments are highly welcome. The alloy properties in focus can be short-term strength and ductility at low and high temperatures, long-term and fatigue strength, creep and toughness, as well as functional properties. You are invited to submit both theoretical and experimental papers.

We are looking forward to your contributions to this Special Issue.

Dr. Igor Yu. Litovchenko
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 submissions that pass pre-check are 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 2600 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

  • Thermomechanical treatment
  • metals
  • alloys
  • grain refinement
  • structure
  • substructure
  • phase transformations
  • precipitation
  • mechanical properties
  • functional properties

Published Papers (19 papers)

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Research

14 pages, 3660 KiB  
Article
Effect of Various Processes on Microstructure of CoCrFeNiAlx High-Entropy Alloy Shot Peening Layer
by Xiaodong Li, Guoqing Gou, Chuanhai Jiang and Jijin Xu
Metals 2023, 13(8), 1441; https://doi.org/10.3390/met13081441 - 11 Aug 2023
Viewed by 678
Abstract
The change in microstructure caused by shot peening can strengthen the material and play an important role in improving the fatigue properties of the material. In order to investigate the related properties such as plastic strain anddislocation activity, the microstructure of CoCrFeNiAlx alloy [...] Read more.
The change in microstructure caused by shot peening can strengthen the material and play an important role in improving the fatigue properties of the material. In order to investigate the related properties such as plastic strain anddislocation activity, the microstructure of CoCrFeNiAlx alloy shot peening layer under different processes was studied. The material exhibited a single austenitic phase, and the FCC crystal structure remained unchanged despite variations in shot peening intensity. Microstructure analysis indicates that with the increase in shot peening intensity, the grain size of the shot peening layer decreases obviously, and the content of microscopic distortion on the surface of the shot peening layer is the highest, and gradually decreases with the increase in depth. At the same time, the roughness of the sample surface is also reduced, which can enhance the fatigue strength and life of the sample. A TEM study revealed the microstructure of the shot peening layer. During the impact of shot peening, the twins produced gradually subdivided the initial grain into smaller slices. With the accumulation of plastic strain, dislocation activity begins to dominate the deformation process. The deformation-induced dislocations accumulate gradually in the small pieces and accumulate into dislocations perpendicular to the secondary twins. These results could be conducive to providing reference and theoretical basis for improving and strengthening the mechanical properties of a series of materials such as high-entropy alloy. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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17 pages, 8716 KiB  
Article
Hot Workability Investigation of an Fe-Al-Ta Alloy Using Deformation Processing Maps
by Aliakbar Emdadi, Heiner Michels and Michael Tovar
Metals 2023, 13(7), 1195; https://doi.org/10.3390/met13071195 - 27 Jun 2023
Cited by 3 | Viewed by 876
Abstract
Fe-Al-Ta alloys are expected to replace high-alloyed steels in steam turbine blades. However, the mechanical properties of the forged blades are still not optimal due to limited grain refinement during hot forging and the coarse-grained microstructure inherited from the as-cast precursor. It is, [...] Read more.
Fe-Al-Ta alloys are expected to replace high-alloyed steels in steam turbine blades. However, the mechanical properties of the forged blades are still not optimal due to limited grain refinement during hot forging and the coarse-grained microstructure inherited from the as-cast precursor. It is, therefore, essential to investigate the hot deformation behavior of the alloy to identify the optimum range for the deformation parameters leading to good hot workability with significant grain refinement. The hot deformation behavior and hot workability of an Fe-25Al-1.5Ta (at.%) alloy were investigated in the present work using constitutive modeling and the concept of processing maps. Uniaxial compression tests were conducted in a strain rate range from 0.0013 s−1 to 1 s−1 and in a temperature range from 900 °C to 1100 °C, where a disordered A2 α-(Fe, Al) matrix phase along with a C14-(Fe, Al)2Ta Laves phase were confirmed by X-ray diffraction. The flow stress–strain curves showed a broad maximum followed by a slight drop in stress until a steady state was reached. The optimum processing window for the studied alloy was located at 910–1060 °C/0.0013–0.005 s−1, where the efficiency of the power dissipation (η) and strain rate sensitivity (m) reached 50% and 0.33, respectively. The material underwent a combination of dynamic recovery and dynamic recrystallization over the whole tested deformation range. No flow instabilities were predicted based on Prasad’s flow instability criterion when deformation was performed up to a true strain of 0.5 and 0.8, indicating a high degree of hot workability of the studied alloy over the entire deformation range tested. The current study reveals a well-suited parameter range for the safe and efficient deformation of Fe-Al-Ta alloys, which may contribute to the optimization of the thermomechanical processing of this alloy. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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20 pages, 7550 KiB  
Article
Flow Behavior and Mechanical Properties of Multi-Pass Thermomechanically Processed 7075 Al-Alloy
by Eman El-Shenawy, Ahmed I. Z. Farahat, Adham E. Ragab, Ahmed Elsayed and Reham Reda
Metals 2023, 13(7), 1158; https://doi.org/10.3390/met13071158 - 22 Jun 2023
Cited by 1 | Viewed by 843
Abstract
Research on multi-pass hot processing of 7075 Al-alloy was rarely discussed. This study aims to design and evaluate different thermomechanical processing strategies (TMPS) to produce 3 mm-thick sheets of 7075 Al-alloy. A physical simulation was performed using the hot compression test of a [...] Read more.
Research on multi-pass hot processing of 7075 Al-alloy was rarely discussed. This study aims to design and evaluate different thermomechanical processing strategies (TMPS) to produce 3 mm-thick sheets of 7075 Al-alloy. A physical simulation was performed using the hot compression test of a Gleeble 3500 to study flow mechanisms and microstructural evolution, while an experimental investigation was carried out using a rolling mill to examine the effect of TMPS on the mechanical properties. Four hot forming strategies were designed and tested at a constant strain rate of 0.1 s−1 over a temperature range of 200–450 °C. These strategies involved applying a constant amount of deformation of 65–70% in single (SP), double (DP), triple (TP), and quadruple (QP) passes of thermomechanical processing to study the influence of multi-pass thermomechanical processing on the final mechanical properties and industrial feasibility. The microstructure analysis showed a significant refinement and more uniform distribution of precipitates with an increasing number of passes, as observed through optical micrographs and the full width at half maximum (FWHM)-position relationship of XRD data. The results indicate that QP is the optimum strategy for producing the best mechanical properties in the shortest production time. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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11 pages, 4087 KiB  
Article
A 4340 Steel with Superior Strength and Toughness Achieved by Heterostructure via Intercritical Quenching and Tempering
by Yi Sang, Guosheng Sun and Jizi Liu
Metals 2023, 13(6), 1139; https://doi.org/10.3390/met13061139 - 19 Jun 2023
Cited by 3 | Viewed by 1756
Abstract
The conventional 4340 steel was used after quenching and tempering, strengthened by the classical pearlitic structure where cementite particles are dispersed through the ferrite matrix. In the present study, a heterostructure microstructure consisting of micro-sized residual ferrite zones and pearlitic zones was introduced [...] Read more.
The conventional 4340 steel was used after quenching and tempering, strengthened by the classical pearlitic structure where cementite particles are dispersed through the ferrite matrix. In the present study, a heterostructure microstructure consisting of micro-sized residual ferrite zones and pearlitic zones was introduced by an optimized process of intercritical quenching and tempering, resulting in a steel with higher strength and better toughness. The pearlite steel has a tensile strength of 1233 MPa, yield strength of 1156 MPa, and toughness of 121.5 MJ/m3. Compared with the pearlite steel, the tensile strength and yield strength of the heterostructure steel have been improved by 67 MPa and 74 MPa, respectively, while the toughness has been increased by 52.5 MJ/m3. In this heterostructure, the micro-sized ferrite bulks serve as the soft zones surrounded by the hard zones of the pearlite structure to achieve a remarkable work-hardening capacity. Statistical analysis shows that the heterostructure has the best hetero-deformation-induced (HDI) hardening capability when the residual ferrite bulk contributes ~31% by volume fraction, and the quenching temperature is around 780 °C. This study opens new ways of thinking about the strengthening and toughening mechanism of heat treatment of medium carbon steels. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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17 pages, 4334 KiB  
Article
Influence of Severe Plastic Deformation by Extrusion on Microstructure, Deformation and Thermal Behavior under Tension of Magnesium Alloy Mg-2.9Y-1.3Nd
by Elena Legostaeva, Anna Eroshenko, Vladimir Vavilov, Vladimir A. Skripnyak, Nikita Luginin, Arsenii Chulkov, Alexander Kozulin, Vladimir V. Skripnyak, Juergen Schmidt, Alexey Tolmachev, Pavel Uvarkin and Yurii Sharkeev
Metals 2023, 13(5), 988; https://doi.org/10.3390/met13050988 - 19 May 2023
Cited by 2 | Viewed by 1207
Abstract
The microstructural investigation, mechanical properties, and accumulation and dissipation of energies of the magnesium alloy Mg-2.9Y-1.3Nd in the recrystallized state and after severe plastic deformation (SPD) by extrusion are presented. The use of SPD provides the formation of a bimodal structure consisting of [...] Read more.
The microstructural investigation, mechanical properties, and accumulation and dissipation of energies of the magnesium alloy Mg-2.9Y-1.3Nd in the recrystallized state and after severe plastic deformation (SPD) by extrusion are presented. The use of SPD provides the formation of a bimodal structure consisting of grains with an average size 15 µm and of ultrafine-grained grains with sizes less than 1 µm and volume fractions up to 50%, as well as of the fine particles of the second Mg24Y5 phases. It is established that grain refinement during extrusion is accompanied by an increase of the yield strength, increase of the tensile strength by 1.5 times, and increase of the plasticity by 1.8 times, all of which are due to substructural hardening, redistribution of the phase composition, and texture formation. Using infrared thermography, it was revealed that before the destruction of Mg-2.9Y-1.3Nd in the recrystallized state, there is a sharp jump of temperature by 10 °C, and the strain hardening coefficient becomes negative and amounts to (−6) GPa. SPD leads to a redistribution of thermal energy over the sample during deformation, does not cause a sharp increase in temperature, and reduces the strain hardening coefficient by 2.5 times. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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9 pages, 2473 KiB  
Article
The Cyclic Stability of Superelasticity in Aged Ti49.3Ni50.7 Single Crystals with Oxide Surface
by Anna S. Eftifeeva, Elena Y. Panchenko, Ilya D. Fatkullin, Mikhail N. Volochaev, Anton I. Tagiltsev and Yuriy I. Chumlyakov
Metals 2022, 12(12), 2113; https://doi.org/10.3390/met12122113 - 08 Dec 2022
Viewed by 741
Abstract
The cyclic stability of superelasticity in compression in [001]B2-oriented Ti49.3Ni50.7 single crystals is considered in this paper. The crystals were aged at 823 K for 1.0 h in air and helium. It has been experimentally shown that a [...] Read more.
The cyclic stability of superelasticity in compression in [001]B2-oriented Ti49.3Ni50.7 single crystals is considered in this paper. The crystals were aged at 823 K for 1.0 h in air and helium. It has been experimentally shown that a two-layered surface thin film, consisting of a Ni-free oxide layer and a Ni-rich sublayer, appears after the oxidation at 823 K in air. The surface layers have a weak effect on the forward B2-R-B19’ martensitic transformation temperatures: TR temperature increases by 4 K; Ms and Mf temperatures decrease by 6 K. The oxide layer does not affect either the superelasticity response during fatigue tests or the temperatures of reverse B19’-B2 martensitic transformation. The cracking of the surface oxide layer during fatigue tests was not found in [001]B2-oriented single crystals aged in air. This is contributed by the relaxation of internal stresses. Such internal stresses are caused by both the formation of an oxide layer during aging and the matrix deformation at the stress-induced martensitic transformation. The main relaxation mechanisms of the internal stresses are the oriented growth of Ti3Ni4 precipitation near a thin surface film at aging in air, the formation of dislocations near the precipitation-matrix interface and a fine twinned B19’-martensite at fatigue tests. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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15 pages, 6478 KiB  
Article
The Microstructure and Tensile Properties of New High-Manganese Low-Activation Austenitic Steel
by Igor Litovchenko, Sergey Akkuzin, Nadezhda Polekhina, Kseniya Almaeva, Valeria Linnik, Anna Kim, Evgeny Moskvichev and Vyacheslav Chernov
Metals 2022, 12(12), 2106; https://doi.org/10.3390/met12122106 - 08 Dec 2022
Cited by 3 | Viewed by 1166
Abstract
Using X-ray diffraction, scanning and transmission electron microscopy, the microstructure of a new low-activation chromium-manganese austenitic steel with a high content of manganese and strong carbide-forming elements is studied. Its structure, dislocation character and particle composition are detailed. The processes taking place in [...] Read more.
Using X-ray diffraction, scanning and transmission electron microscopy, the microstructure of a new low-activation chromium-manganese austenitic steel with a high content of manganese and strong carbide-forming elements is studied. Its structure, dislocation character and particle composition are detailed. The processes taking place in the steel under cold-rolling deformation are described. It is shown that the mechanical properties of the new high-manganese steel revealed by testing at 20 and 650 °C are comparable with those of well-known analogs or exceed them. Relying on the structural studies, this is attributed to the dispersion and substructural strengthening. Better plastic properties of the steel are associated with the twinning-induced plasticity effect. It is shown that the steel fracture after tension at the test temperatures is mainly ductile dimple transcrystalline with the elements of ductile intercrystalline fracture (at 20 °C), while at 650 °C the signs of the latter disappear. The low-activation chromium-manganese austenitic steels characterized by increased austenite stability are thought to be promising structural materials for nuclear power engineering. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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20 pages, 11311 KiB  
Article
The Microstructure, Tensile and Impact Properties of Low-Activation Ferritic-Martensitic Steel EK-181 after High-Temperature Thermomechanical Treatment
by Nadezhda Polekhina, Valeria Linnik, Igor Litovchenko, Kseniya Almaeva, Sergey Akkuzin, Evgeny Moskvichev, Vyacheslav Chernov, Mariya Leontyeva-Smirnova, Nikolay Degtyarev and Kirill Moroz
Metals 2022, 12(11), 1928; https://doi.org/10.3390/met12111928 - 10 Nov 2022
Cited by 3 | Viewed by 1228
Abstract
In this work, we study the effect of high-temperature thermomechanical treatment (HTMT) with deformation in the austenite region on the microstructure, tensile properties, impact toughness, and fracture features of advanced low-activation 12% chromium ferritic-martensitic reactor steel EK-181. HTMT more significantly modifies the steel [...] Read more.
In this work, we study the effect of high-temperature thermomechanical treatment (HTMT) with deformation in the austenite region on the microstructure, tensile properties, impact toughness, and fracture features of advanced low-activation 12% chromium ferritic-martensitic reactor steel EK-181. HTMT more significantly modifies the steel structural-phase state than the traditional heat treatment (THT). As a result of HTMT, the hierarchically organized structure of steel is refined. The forming grains and subgrains are elongated in the rolling direction and flattened in the rolling plane (so-called pancake structure) and have a high density of dislocations pinned by stable nanosized particles of the MX type. This microstructure provides a simultaneous increase, relative to THT, in the yield strength and impact toughness of steel EK-181 and does not practically change its ductile-brittle transition temperature. The most important reasons for the increase in impact toughness are a decrease in the effective grain size of steel (martensite blocks and ferrite grains) and the appearance of a crack-arrester type delamination perpendicular to the main crack propagation direction. This causes branching of the main crack and an increase in the absorbed impact energy. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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12 pages, 2444 KiB  
Article
Investigation of the Effect of Copper Addition on Physical and Mechanical Properties of TiNi-Cu Porous Alloy
by Maria Kaftaranova, Valentina Hodorenko, Sergey Anikeev, Nadezhda Artyukhova, Anastasiia V. Shabalina and Victor Gunther
Metals 2022, 12(10), 1696; https://doi.org/10.3390/met12101696 - 11 Oct 2022
Cited by 3 | Viewed by 1092
Abstract
This work is devoted to the physical and mechanical properties of porous alloys based on TiNi alloyed with different amounts of Cu additive. We show that by doping a porous TiNi alloy with copper instead of nickel, it is possible to obtain characteristics [...] Read more.
This work is devoted to the physical and mechanical properties of porous alloys based on TiNi alloyed with different amounts of Cu additive. We show that by doping a porous TiNi alloy with copper instead of nickel, it is possible to obtain characteristics acceptable for use in implantology and superior to those of known porous TiNi alloys. Cu addition in the range from 1 to 10 at.% is shown to optimize the properties of tested alloys. There is a decrease in the minimal martensitic transformation stress τMsmin from 37 to 17 MPa when compared to initial unalloyed TiNi. Alloys with 3 and 6 at.% of Cu are found to be optimal for use in medical practice. Along with a wide temperature range of reversible deformations that cover the range of operating temperatures (273–313 K), such alloys demonstrate their martensitic transformation stress values below 28 MPs. This permits to model implantable structures of complex configuration from such materials under a certain temperature regime. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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19 pages, 16840 KiB  
Article
Deformation Behavior of Two-Phase Gradient Nanograined Fe95Ni5 Alloys under Different Types of Loading
by Aleksandr Korchuganov, Dmitrij Kryzhevich and Konstantin Zolnikov
Metals 2022, 12(9), 1492; https://doi.org/10.3390/met12091492 - 09 Sep 2022
Cited by 1 | Viewed by 1064
Abstract
In this paper, we used molecular dynamics simulations to study the atomic mechanisms of phase transformations, plasticity features, and mechanical properties of two-phase Fe95Ni5 (at. %) samples with a gradient nanograined structure under uniaxial deformation and shear. The simulated samples [...] Read more.
In this paper, we used molecular dynamics simulations to study the atomic mechanisms of phase transformations, plasticity features, and mechanical properties of two-phase Fe95Ni5 (at. %) samples with a gradient nanograined structure under uniaxial deformation and shear. The simulated samples with a uniform distribution of Ni atoms are composed of fcc grains from 10 to 30 nm in size, which in turn contain bcc interlayers in the form of lamellae of various distribution and size. It was shown that uniaxial loading or shear causes the bcc-fcc phase transformation in the lamellae. In the vast majority of cases, phase transformations are initiated at the junction of lamellae and grain boundaries. Deformation-induced phase transformations in lamellae occur at the front of bands propagating from grain boundaries. Grains larger than ~15 nm can have several bands or regions with differently orientated fcc lattices, whose meeting results in grain fragmentation. It was found that the atomic volume increases abruptly during the bcc-fcc structural phase transformation. The Kurdyumov–Sachs orientation relation is valid between the initial bcc and formed fcc structures. It was shown that the volume fraction and spatial distribution of the bcc phase significantly affect the yield stress of the sample. The yield stress can be increased by forming the bcc phase only in large-grained layers. This behavior is associated with the fragmentation of large grains, and consequently with grain refinement, which, in accordance with the Hall–Petch relation, improves the strength of the material. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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18 pages, 1823 KiB  
Article
Thermodynamic Properties and Equation of State for Solid and Liquid Aluminum
by Nikolay V. Kozyrev and Vladimir V. Gordeev
Metals 2022, 12(8), 1346; https://doi.org/10.3390/met12081346 - 13 Aug 2022
Cited by 4 | Viewed by 2495
Abstract
High-temperature equations of state for solid and liquid aluminum were constructed herein using experimental data on thermodynamic properties, thermal expansion, compressibility, bulk modulus and sound velocity measurements, supplemented with phase diagram data (melting curve). The entire set of experimental data was optimized using [...] Read more.
High-temperature equations of state for solid and liquid aluminum were constructed herein using experimental data on thermodynamic properties, thermal expansion, compressibility, bulk modulus and sound velocity measurements, supplemented with phase diagram data (melting curve). The entire set of experimental data was optimized using the temperature-dependent Tait equation over a pressure range of up to 800 kbar and over a temperature range from 20 K to the melting point for solid aluminum and to 3800 K for liquid aluminum. The temperature dependence of thermodynamic and thermophysical parameters was described by an expanded Einstein model. The resultant equations of state describe well the totality of experimental data within measurement errors of individual variables. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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30 pages, 51131 KiB  
Article
Development of Ultrafine–Grained and Nanostructured Bioinert Alloys Based on Titanium, Zirconium and Niobium and Their Microstructure, Mechanical and Biological Properties
by Yurii Sharkeev, Anna Eroshenko, Elena Legostaeva, Zhanna Kovalevskaya, Olga Belyavskaya, Margarita Khimich, Matthias Epple, Oleg Prymak, Viktoriya Sokolova, Qifang Zhu, Zeming Sun and Hongju Zhang
Metals 2022, 12(7), 1136; https://doi.org/10.3390/met12071136 - 02 Jul 2022
Cited by 12 | Viewed by 1675
Abstract
For this paper, studies of the microstructure as well as the mechanical and biological properties of bioinert titanium, zirconium, and niobium alloys in their nanostructured (NS) and ultrafine-grained (UFG) states have been completed. The NS and UFG states were formed by a combined [...] Read more.
For this paper, studies of the microstructure as well as the mechanical and biological properties of bioinert titanium, zirconium, and niobium alloys in their nanostructured (NS) and ultrafine-grained (UFG) states have been completed. The NS and UFG states were formed by a combined two-step method of severe plastic deformation (SPD), first with multidirectional forging (MDF) or pressing into a symmetrical channel (PSC) at a given temperature regime, and then subsequent multi-pass groove rolling (MPGR) at room temperature, with pre-recrystallization annealing. Annealing increased the plasticity of the alloys in the NS and UFG states without changing the grain size. The UFG structure, with an average size of structural elements of no more than 0.3 μm, was formed as a result of applying two-step SPD and annealing. This structure presented significant improvement in the mechanical characteristics of the alloys, in comparison with the alloys in the coarse-grained (CG) or small-grained (SG) states. At the same time, although the formation of the UFG structure leads to a significant increase in the yield strength and tensile strength of the alloys, their elastic modulus did not change. In terms of biocompatibility, the cultivation of MG-63 osteosarcoma cells on the polished and sandblasted substrates demonstrated high cell viability after 10 days and good cell adhesion to the surface. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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11 pages, 3549 KiB  
Article
Influence of Wire Geometry on the Mechanical Behavior of the TiNi Design
by Gulsharat Baigonakova, Ekaterina Marchenko, Marina Kovaleva and Alexander Vorozhtsov
Metals 2022, 12(7), 1131; https://doi.org/10.3390/met12071131 - 01 Jul 2022
Cited by 2 | Viewed by 1490
Abstract
The present article is aimed at studying the deformation behavior of TiNi wire and knitted metal TiNi mesh under uniaxial tension and revealing the role of wire geometry on their main mechanical characteristics and mechanisms of deformation behavior. The temperature dependence curve of [...] Read more.
The present article is aimed at studying the deformation behavior of TiNi wire and knitted metal TiNi mesh under uniaxial tension and revealing the role of wire geometry on their main mechanical characteristics and mechanisms of deformation behavior. The temperature dependence curve of the electrical resistance indicates that a two-stage martensitic transformation of B2→R→B19′ is occurring, and is responsible for the superelasticity effect. The TEM results showed that at room temperature, the TiNi wire has a nanocrystalline structure composed of B2 austenite grains. A change in the deformation mechanism was established under the uniaxial tension, where the TiNi wire exhibits the effect of superelasticity, while the knitted metal TiNi mesh made from this wire is characterized by hyperelastic behavior. Fracturing of the knitted metal TiNi mesh requires significant loads of up to 3500 MPa compared to the fracture load of the TiNi wire. With the uniaxial tension of the wire, which maximally repeats the geometry of the wire in knitted metal mesh, an increase in mechanical characteristics was observed. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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13 pages, 6620 KiB  
Article
In Vitro Bio-Testing Comparative Analysis of NiTi Porous Alloys Modified by Heat Treatment
by Ekaterina Marchenko, Gulsharat Baigonakova, Kirill Dubovikov, Oleg Kokorev, Yuri Yasenchuk and Alexander Vorozhtsov
Metals 2022, 12(6), 1006; https://doi.org/10.3390/met12061006 - 13 Jun 2022
Cited by 4 | Viewed by 1669
Abstract
The present work is aimed at studying the surface cytocompatibility of porous NiTi obtained by self-propagating high temperature synthesis (SHS), and then annealed in air at 500–1000 °C. Using cytotoxicity tests in vitro, it was found that the cells had attached to the [...] Read more.
The present work is aimed at studying the surface cytocompatibility of porous NiTi obtained by self-propagating high temperature synthesis (SHS), and then annealed in air at 500–1000 °C. Using cytotoxicity tests in vitro, it was found that the cells had attached to the oxidized surface in the amount sufficient for their growth and proliferation on the substrate. The surfaces of the annealed samples and the control sample were studied by XRD, SEM and optical microscopy. It was found that there is a correlation between cell hemolysis and nickel-containing phases on the surface. Thus, annealing at 500–700 °C worsens cytocompatibility compared to the control sample, but annealing at 800–1000 °C improves cytocompatibility. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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13 pages, 8764 KiB  
Article
The Contribution of Various Plasticity Mechanisms to the Deformation Behavior of Gradient Nanograined FeNi Alloy
by Aleksandr V. Korchuganov, Konstantin P. Zolnikov and Dmitrij S. Kryzhevich
Metals 2022, 12(4), 573; https://doi.org/10.3390/met12040573 - 28 Mar 2022
Cited by 4 | Viewed by 1471
Abstract
This paper investigates the deformation behavior of a gradient grained FeNi sample under uniaxial tension using molecular dynamics simulations. The simulated sample consists of five layers with grains of the same size in each layer ranging from 10 to 30 nm. It is [...] Read more.
This paper investigates the deformation behavior of a gradient grained FeNi sample under uniaxial tension using molecular dynamics simulations. The simulated sample consists of five layers with grains of the same size in each layer ranging from 10 to 30 nm. It is shown that the sample plasticity develops through sequential activation of different mechanisms. These are either the generation of certain structural defects, or grain boundary migration, or grain boundary sliding. The onset of plasticity is provided by partial dislocations that produce stacking faults in large grains. Other mechanisms involved in plastic deformation are the nucleation of trailing/full dislocations and twinning, which gradually affect smaller and smaller grains. Grain boundary sliding is more intensive in smallest grains due to their less constraint. Grain boundary migration generally leads to the growth of large grains. At strains below 7.0%, plasticity is mainly contributed by the evolution of stacking faults. At higher strains, the main plasticity mechanisms are twinning and grain boundary migration. As the strain increases, the maximum values of accumulated shear, the density of intragranular defects, and the number of atoms involved in intergranular rearrangements are observed first in large, then in medium, and finally in small grains. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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12 pages, 3388 KiB  
Article
Influence of a Thermo-Mechanical Treatment on the Fatigue Lifetime and Crack Initiation Behavior of a Quenched and Tempered Steel
by Amin Khayatzadeh, Jan Sippel, Stefan Guth, Karl-Heinz Lang and Eberhard Kerscher
Metals 2022, 12(2), 204; https://doi.org/10.3390/met12020204 - 22 Jan 2022
Cited by 5 | Viewed by 2551
Abstract
A thermo-mechanical treatment (TMT) at the temperature of maximum dynamic strain aging has been optimized and performed on quenched and tempered steel SAE4140H (German designation: 42CrMo4) in order to improve the fatigue limit in the high cycle fatigue (HCF) and and very high [...] Read more.
A thermo-mechanical treatment (TMT) at the temperature of maximum dynamic strain aging has been optimized and performed on quenched and tempered steel SAE4140H (German designation: 42CrMo4) in order to improve the fatigue limit in the high cycle fatigue (HCF) and and very high cycle fatigue (VHCF) regimes. Fatigue tests, with ultimate cycle numbers of 107 and 109, have shown that the TMT can increase both the fatigue lifetime and the fatigue limit in the HCF and VHCF regimes. The increased stress intensity factors of the critical inclusions after the TMT indicate that the effect can be attributed to a stabilized microstructure around critical crack-initiating inclusions through the locking of edge dislocations by carbon atoms during the TMT. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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13 pages, 9022 KiB  
Article
The Microstructure and Mechanical Properties of Ferritic-Martensitic Steel EP-823 after High-Temperature Thermomechanical Treatment
by Igor Litovchenko, Kseniya Almaeva, Nadezhda Polekhina, Sergey Akkuzin, Valeria Linnik, Evgeny Moskvichev, Vyacheslav Chernov and Maria Leontyeva-Smirnova
Metals 2022, 12(1), 79; https://doi.org/10.3390/met12010079 - 04 Jan 2022
Cited by 12 | Viewed by 1680
Abstract
The effect of high-temperature thermomechanical treatment (HTMT) with plastic deformation by rolling in austenitic region on the microstructure and mechanical properties of 12% chromium ferritic-martensitic steel EP-823 is investigated. The features of the grain and defect microstructure of steel are studied by Scanning [...] Read more.
The effect of high-temperature thermomechanical treatment (HTMT) with plastic deformation by rolling in austenitic region on the microstructure and mechanical properties of 12% chromium ferritic-martensitic steel EP-823 is investigated. The features of the grain and defect microstructure of steel are studied by Scanning Electron Microscopy with Electron Back-Scatter Diffraction (SEM EBSD) and Transmission Electron Microscopy (TEM). It is shown that HTMT leads to the formation of pancake structure with grains extended in the rolling direction and flattened in the rolling plane. The average sizes of martensitic packets and ferrite grains are approximately 1.5–2 times smaller compared to the corresponding values after traditional heat treatment (THT, which consists of normalization and tempering). The maximum grain size in the section parallel to the rolling plane increases up to more than 80 µm. HTMT leads to the formation of new sub-boundaries and a higher dislocation density. The fraction of low-angle misorientation boundaries reaches up to ≈68%, which exceeds the corresponding value after HTMT (55%). HTMT does not practically affect the carbide subsystem of steel. The mechanical properties are investigated by tensile tests in the temperature range 20–700 °C. It is shown that the values of the yield strength in this temperature range after HTMT increase relative to the corresponding values after THT. As a result of HTMT, the elongation decreases. A significant decrease is observed in the area of dynamic strain aging (DSA). The mechanisms of plastic deformation and strengthening of ferritic-martensitic steel under the high-temperature thermomechanical treatments are also discussed. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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16 pages, 7291 KiB  
Article
Effect of Multistage High Temperature Thermomechanical Treatment on the Microstructure and Mechanical Properties of Austenitic Reactor Steel
by Sergey Akkuzin, Igor Litovchenko, Nadezhda Polekhina, Kseniya Almaeva, Anna Kim, Evgeny Moskvichev and Vyacheslav Chernov
Metals 2022, 12(1), 63; https://doi.org/10.3390/met12010063 - 28 Dec 2021
Cited by 8 | Viewed by 1390
Abstract
The deformation microstructures formed by novel multistage high-temperature thermomechanical treatment (HTMT) and their effect on the mechanical properties of austenitic reactor steel are investigated. It is shown that HTMT with plastic deformation at the temperature decreasing in each stage (1100, 900, and 600 [...] Read more.
The deformation microstructures formed by novel multistage high-temperature thermomechanical treatment (HTMT) and their effect on the mechanical properties of austenitic reactor steel are investigated. It is shown that HTMT with plastic deformation at the temperature decreasing in each stage (1100, 900, and 600 °C with a total strain degree of e = 2) is an effective method for refining the grain structure and increasing the strength of the reactor steel. The structural features of grains, grain boundaries and defective substructure of the steel are studied in two sections (in planes perpendicular to the transverse direction and perpendicular to the normal direction) by Scanning Electron Microscopy with Electron Back-Scatter Diffraction (SEM EBSD) and Transmission Electron Microscopy (TEM). After the multistage HTMT, a fragmented structure is formed with grains elongated along the rolling direction and flattened in the rolling plane. The average grain size decreases from 19.3 µm (for the state after solution treatment) to 1.8 µm. A high density of low-angle boundaries (up to ≈ 80%) is found inside deformed grains. An additional cold deformation (e = 0.3) after the multistage HTMT promotes mechanical twinning within fragmented grains and subgrains. The resulting structural states provide high strength properties of steel: the yield strength increases up to 910 MPa (at 20 °C) and up to 580 MPa (at 650 °C), which is 4.6 and 6.1 times higher than that in the state after solution treatment (ST), respectively. The formation of deformed substructure and the influence of dynamic strain aging at an elevated tensile temperature on the mechanical properties of the steel are discussed. Based on the results obtained, the multistage HTMT used in this study can be applied for increasing the strength of austenitic steels. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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19 pages, 10383 KiB  
Article
Thermodynamic Characterization and Equation of State for Solid and Liquid Lead
by Nikolay V. Kozyrev and Vladimir V. Gordeev
Metals 2022, 12(1), 16; https://doi.org/10.3390/met12010016 - 22 Dec 2021
Cited by 4 | Viewed by 2529
Abstract
A high-temperature equation of state (EoS) for the fcc phase of solid lead and liquid lead was developed herein using experimental data on thermodynamic properties, volumetric thermal expansion, compressibility, temperature-dependent bulk modulus, and sound velocity from ultrasonic measurements and melting curve. The whole [...] Read more.
A high-temperature equation of state (EoS) for the fcc phase of solid lead and liquid lead was developed herein using experimental data on thermodynamic properties, volumetric thermal expansion, compressibility, temperature-dependent bulk modulus, and sound velocity from ultrasonic measurements and melting curve. The whole totality of experimental data was optimized using the temperature-dependent Murnaghan EoS over a pressure range of 0–130 kbar. The temperature dependences of thermodynamic and thermophysical parameters were described herein using an expanded Einstein model. The resultant EoS describes well the whole set of available experimental data within measurement uncertainties of individual parameters. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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