Materials

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15 pages, 4971 KiB

Open AccessArticle

The Effect of Radial-Shear Rolling Deformation Processing on the Structure and Properties of Zr-2.5Nb Alloy

by Kirill Ozhmegov, Anna Kawalek, Abdrakhman Naizabekov, Evgeniy Panin, Nikita Lutchenko, Sanzhar Sultanbekov, Medet Magzhanov and Alexandr Arbuz

Materials 2023, 16(10), 3873; https://doi.org/10.3390/ma16103873 - 21 May 2023

Cited by 3 | Viewed by 1499

Abstract

The rheological properties of the Zr-2.5Nb alloy by the strain rate range of 0.5–15 s⁻¹ and by the temperature range of 20–770 °C was studied. The dilatometric method for phase states temperature ranges was experimentally determined. A material properties database for computer [...] Read more.

The rheological properties of the Zr-2.5Nb alloy by the strain rate range of 0.5–15 s⁻¹ and by the temperature range of 20–770 °C was studied. The dilatometric method for phase states temperature ranges was experimentally determined. A material properties database for computer FEM simulation regards the indicated temperature-velocity ranges were created. Using this database and DEFORM-3D FEM-softpack, the radial shear rolling complex process numerical simulation was carried out. The contributed conditions for the ultrafine-grained state alloy structure refinement were determined. Based on the simulation results, a full-scale experiment of Zr-2.5Nb rod rolling a on a radial-shear rolling mill RSP-14/40 was carried out. It takes in seven passes from a diameter of 37–20 mm with a total diameter reduction ε = 85%. According to this case simulation data, the total equivalent strain in the most processed peripheral zone 27.5 mm/mm was reached. Due to the complex vortex metal flow, the equivalent strain over the section distribution was uneven with a gradient reducing towards the axial zone. This fact should have a deep effect on the structure change. Changes and structure gradient by sample section EBSD mapping with 2 mm resolution were studied. The microhardness section gradient by the HV 0.5 method was also studied. The axial and central zones of the sample by the TEM method were studied. The rod section structure has an expressed gradient from the formed equiaxed ultrafine-grained (UFG) structure on a few outer millimeters of the peripheral section to the elongated rolling texture in the center of the bar. The work shows the possibility of processing with the gradient structure obtaining and enhanced properties for the Zr-2.5Nb alloy, and a database for this alloy FEM numerical simulations are also presents. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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18 pages, 7694 KiB

Open AccessArticle

On the Competition between Intergranular and Transgranular Failure within 7xxx Al Alloys with Tailored Microstructures

by Sutao Han, Matthieu B. Lezaack, Grzegorz Pyka, Nelson Netto, Aude Simar, Magd Abdel Wahab and Florent Hannard

Materials 2023, 16(10), 3770; https://doi.org/10.3390/ma16103770 - 16 May 2023

Cited by 6 | Viewed by 1478

Abstract

7xxx aluminium series reach exceptional strength compared to other industrial aluminium alloys. However, 7xxx aluminium series usually exhibit Precipitate-Free Zones (PFZs) along grain boundaries, which favour intergranular fracture and low ductility. In this study, the competition between intergranular and transgranular fracture is experimentally [...] Read more.

7xxx aluminium series reach exceptional strength compared to other industrial aluminium alloys. However, 7xxx aluminium series usually exhibit Precipitate-Free Zones (PFZs) along grain boundaries, which favour intergranular fracture and low ductility. In this study, the competition between intergranular and transgranular fracture is experimentally investigated in the 7075 Al alloy. This is of critical importance since it directly affects the formability and crashworthiness of thin Al sheets. Using Friction Stir Processing (FSP), microstructures with similar hardening precipitates and PFZs, but with very different grain structures and intermetallic (IM) particle size distribution, were generated and studied. Experimental results showed that the effect of microstructure on the failure mode was significantly different for tensile ductility compared to bending formability. While the tensile ductility was significantly improved for the microstructure with equiaxed grains and smaller IM particles (compared to elongated grains and larger particles), the opposite trend was observed in terms of formability. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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12 pages, 3978 KiB

Open AccessArticle

Strengthening Mechanism of Rotary-Forged Deformable Biodegradable Zn-0.45Li Alloys

by Feng Ding, Yi Zhang, Xinglong Zhu, Pushan Guo, Lijing Yang, Qingke Zhang, Cheng Xu, Wensheng Sun and Zhenlun Song

Materials 2023, 16(8), 3003; https://doi.org/10.3390/ma16083003 - 10 Apr 2023

Cited by 4 | Viewed by 1644

Abstract

The use of zinc (Zn) alloys as a biodegradable metal for medical purposes has been a popular research topic. This study investigated the strengthening mechanism of Zn alloys to enhance their mechanical properties. Three Zn-0.45Li (wt.%) alloys with different deformation amounts were prepared [...] Read more.

The use of zinc (Zn) alloys as a biodegradable metal for medical purposes has been a popular research topic. This study investigated the strengthening mechanism of Zn alloys to enhance their mechanical properties. Three Zn-0.45Li (wt.%) alloys with different deformation amounts were prepared by rotary forging deformation. Their mechanical properties and microstructures were tested. A simultaneous increase in strength and ductility was observed in the Zn-0.45Li alloys. Grain refinement occurred when the rotary forging deformation reached 75.7%. The surface average grain size reached 1.19 ± 0.31 μm, and the grain size was uniformly distributed. Meanwhile, the maximum elongation of the deformed Zn-0.45Li was 139.2 ± 18.6%, and the ultimate tensile strength reached 426.1 ± 4.7 MPa. In situ tensile tests showed that the reinforced alloys still broke from the grain boundary. Continuous and discontinuous dynamic recrystallization during severe plastic deformation produced many recrystallized grains. During deformation, the dislocation density of the alloy first increased and then decreased, and the texture strength of the (0001) direction increased with deformation. Analysis of the mechanism of alloy strengthening showed that the strength and plasticity enhancement of Zn-Li alloys after macro deformation was a combination of dislocation strengthening, weave strengthening, and grain refinement rather than only fine-grain strengthening as observed in conventional macro-deformed Zn alloys. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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23 pages, 4755 KiB

Open AccessArticle

The Effect of Addition Potassium Permanganate on Bond Strength of Hot-Dip Galvanized Plain Bars with Cement Paste

by Petr Pokorný, Vítězslav Vacek, Nikola Prodanovic, Adam Zabloudil and Karel Hurtig

Materials 2023, 16(7), 2556; https://doi.org/10.3390/ma16072556 - 23 Mar 2023

Cited by 1 | Viewed by 1843

Abstract

In this paper, the effect of gradually increasing amounts of KMnO₄ (10⁻⁴, 10⁻³, 10⁻² mol·L⁻¹) in cement paste on the bond strength of a plain hot-dip galvanized steel bar was evaluated. The open-circuit potential of [...] Read more.

In this paper, the effect of gradually increasing amounts of KMnO₄ (10⁻⁴, 10⁻³, 10⁻² mol·L⁻¹) in cement paste on the bond strength of a plain hot-dip galvanized steel bar was evaluated. The open-circuit potential of HDG samples in cement paste with various additions of MnO₄⁻ was monitored in order to follow a transfer of zinc from activity to passivity. Furthermore, the influence of the addition of these anions on the physicochemical properties of normal-strength concrete or cement paste was evaluated by means of hydration heat measurements, X-ray diffraction analysis, and compressive strength. The effective concentration of MnO₄⁻ anions prevents the corrosion of the coating with hydrogen evolution and ensures that the bond strength is not reduced by their action, which was determined to be 10⁻³ mol·L⁻¹. Lower additions of MnO₄⁻ anions (10⁻⁴ mol·L⁻¹) are ineffective in this respect. On the other hand, higher additions of MnO₄⁻ anions (10⁻² mol·L⁻¹), although they ensure the corrosion of the coating in fresh concrete without hydrogen evolution, but affect the hydration process of the cement paste that was demonstrated by slight water separation. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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14 pages, 6909 KiB

Open AccessArticle

Obtaining an Equiaxed Ultrafine-Grained State of the Longlength Bulk Zirconium Alloy Bars by Extralarge Shear Deformations with a Vortex Metal Flow

by Alexandr Arbuz, Anna Kawalek, Kirill Ozhmegov, Evgeniy Panin, Medet Magzhanov, Nikita Lutchenko and Vasily Yurchenko

Materials 2023, 16(3), 1062; https://doi.org/10.3390/ma16031062 - 25 Jan 2023

Cited by 7 | Viewed by 1377

Abstract

The method of radial shear rolling makes it possible to achieve comparable to high pressure torsion (HPT) method ultrahigh degrees of total strain level in combination with the vortex metal flow character for long-length large bulk bars unable by HPT and many other [...] Read more.

The method of radial shear rolling makes it possible to achieve comparable to high pressure torsion (HPT) method ultrahigh degrees of total strain level in combination with the vortex metal flow character for long-length large bulk bars unable by HPT and many other processes of sever plastic deformation (SPD). Sequential rolling of the Zr-1%Nb alloy was carried out under extreme conditions on two radial shear rolling mills with a total diameter reduction ε = 185% and a maximum total strain level = 46 mm/mm. The strain level and its cross-section distribution assessment by finite element method (FEM) simulation was studied. The final bar cross-section structure type distribution detailed study 1 mm resolution by electron back scatter diffraction (EBSD) mapping was performed. A gradient structure with a predominance of the equiaxed ultrafine-grained (UFG) state was found. The deformation level rising did not allow to refine it in the periphery zone more than that obtained nearly middle of the processing, but it allows for significant change in the axial zone structure. The additional large warm deformations by radial shear rolling have no additional grain refinement effect for already 300–600 nm refined zone. An equiaxed UFG structure was obtained in a relatively large volume of the sample with a reduced gradient towards the non-UFG center zone in regard to known works. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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11 pages, 4389 KiB

Open AccessArticle

Ultrafine-Grained Zn–Mg–Sr Alloy Synthesized by Mechanical Alloying and Spark Plasma Sintering

by David Nečas, Jiří Kubásek, Jan Pinc, Ivo Marek, Črtomir Donik, Irena Paulin and Dalibor Vojtěch

Materials 2022, 15(23), 8379; https://doi.org/10.3390/ma15238379 - 24 Nov 2022

Cited by 4 | Viewed by 1489

Abstract

Zinc materials are considered promising candidates for bioabsorbable medical devices used for the fixation of broken bones or stents. Materials for these applications must meet high mechanical property requirements. One of the ways to fulfil these demands is related to microstructure refinement, particularly [...] Read more.

Zinc materials are considered promising candidates for bioabsorbable medical devices used for the fixation of broken bones or stents. Materials for these applications must meet high mechanical property requirements. One of the ways to fulfil these demands is related to microstructure refinement, particularly the decrease in grain size. In the present work, we combine two powder metallurgy techniques (mechanical alloying—MA, and spark plasma sintering—SPS) to prepare Zn–1Mg–0.5Sr nanograin material. The microstructure of compacted material consisted of Zn grains and particles of Mg₂Zn₁₁ intermetallic phases from 100 to 500 nm in size, which resulted in high values of hardness and a compressive strength equal to 86 HV1 and 327 MPa, respectively. In this relation, the combination of the suggested techniques provides an innovative way to form extremely fine microstructures without significant coarsening during powder compaction at increased temperatures. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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11 pages, 5210 KiB

Open AccessArticle

Effect of BASC and BASCA Heat Treatment on Microstructure and Mechanical Properties of TC10 Titanium Alloy

by Mingyu Zhang, Xinbing Yun and Hongwang Fu

Materials 2022, 15(22), 8249; https://doi.org/10.3390/ma15228249 - 21 Nov 2022

Viewed by 1781

Abstract

The purpose of this study is to investigate two new heat treatment processes on the mechanical properties of TC10 titanium alloy. By changing the β annealing temperature, the variation in microstructure and mechanical properties of TC10 titanium alloy were investigated. The results showed [...] Read more.

The purpose of this study is to investigate two new heat treatment processes on the mechanical properties of TC10 titanium alloy. By changing the β annealing temperature, the variation in microstructure and mechanical properties of TC10 titanium alloy were investigated. The results showed that with the increase in β annealing temperature the microstructure type changes from an equiaxed structure to a lamellar structure. The strength of the alloy then increases firstly, followed by a decrease, while the plasticity decreases all the time. Microstructure observation revealed that the alloy is uniformly composed of α phase and β phase after the two processes. In addition, it was found that the fracture morphology of the equiaxed structure is mainly dimples, showing ductile fracture characteristics, while the fracture morphology of lamellar microstructure is mainly crystalline, showing brittle fracture characteristics. These results indicated that reasonable β annealing temperature can be set according to different requirements to obtain different types of microstructure and mechanical properties, which expands the application field of TC10 titanium alloy. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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31 pages, 13008 KiB

Open AccessArticle

The Influence of Graded Amount of Potassium Permanganate on Corrosion of Hot-Dip Galvanized Steel in Simulated Concrete Pore Solutions

by Petr Pokorný, Vítězslav Vacek, Nikola Prodanovic, Adam Zabloudil, Jaroslav Fojt and Viktor Johánek

Materials 2022, 15(21), 7864; https://doi.org/10.3390/ma15217864 - 7 Nov 2022

Cited by 6 | Viewed by 2407

Abstract

This paper evaluates the amount of KMnO₄ in simulated concrete pore solution (pH 12.8) on the corrosion behaviour of hot-dip galvanized steel (HDG). In the range of used MnO₄⁻ (10⁻⁴, 10⁻³, 10⁻² mol·L⁻¹), [...] Read more.

This paper evaluates the amount of KMnO₄ in simulated concrete pore solution (pH 12.8) on the corrosion behaviour of hot-dip galvanized steel (HDG). In the range of used MnO₄⁻ (10⁻⁴, 10⁻³, 10⁻² mol·L⁻¹), corrosion behaviour is examined with regard to hydrogen evolution and composition (protective barrier properties) of forming corrosion products. The corrosion behaviour of HDG samples is evaluated using R_p/E_corr and EIS. The composition of corrosion products is evaluated using SEM, XRD, XPS and AAS. The effective MnO₄⁻ ion concentration to prevent the corrosion of coating with hydrogen evolution is 10⁻³ mol·L⁻¹; lower concentrations only prolong the time to passivation (corrosion with hydrogen evolution). The highest used MnO₄⁻ concentration ensures corrosion behaviour without hydrogen evolution but also leads to the formation of less-protective amorphous corrosion products rich in Mn^II/Mn^III phases. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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10 pages, 4178 KiB

Open AccessArticle

Simultaneous Improvement of Strength and Ductility of Dual-Phase Steel Processed by Multi-Step Cyclic Rolling and Intercritical Annealing

by Litao Liu, Bin Fu, Yanhui Guo and Liqun Wei

Materials 2022, 15(18), 6424; https://doi.org/10.3390/ma15186424 - 16 Sep 2022

Cited by 1 | Viewed by 1431

Abstract

In the present study, a multi-step (MS) cyclic rolling and intercritcal annealing process was proposed and applied for dual-phase (DP) steel. The MS process performed three times with 27% deformations and intercritical annealing, while the single-step (SS) process performed an 81% rolling, along [...] Read more.

In the present study, a multi-step (MS) cyclic rolling and intercritcal annealing process was proposed and applied for dual-phase (DP) steel. The MS process performed three times with 27% deformations and intercritical annealing, while the single-step (SS) process performed an 81% rolling, along with intercritical annealing. A microstructure with an average grain size of 3 μm and a martensite content of ~40% was obtained after MS treatment, which is similar to results obtained from the SS treatment. However, the distribution exhibits significant differences between the two different routes. A more homogenous distribution of ferrite–martensite was achieved after the multi-step compared with the single-step treatment. The yield strength of MS is slightly smaller than that of SS, while the ultimate tensile strength is better, which results in a decrease in yield ratio. Furthermore, the ductility was greatly improved after MS, which is mainly attributed to the uniform chain-like distribution of martensite. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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13 pages, 4307 KiB

Open AccessArticle

Heat Treatment of Aluminum Alloys with the Natural Combination of Dopants

by Alisa Tsepeleva, Pavel Novák, Evdokim Kolesnichenko, Alena Michalcová, Zdeněk Kačenka and Jiří Kubásek

Materials 2022, 15(16), 5541; https://doi.org/10.3390/ma15165541 - 12 Aug 2022

Cited by 2 | Viewed by 1974

Abstract

Aluminothermic reduction without the separation of individual metals is currently considered as a possible method for processing ferromanganese sea nodules and creating new alloys. In this study, the product of their reduction—a manganese-based polymetallic mixture—was added to pure aluminum, as a mixture of [...] Read more.

Aluminothermic reduction without the separation of individual metals is currently considered as a possible method for processing ferromanganese sea nodules and creating new alloys. In this study, the product of their reduction—a manganese-based polymetallic mixture—was added to pure aluminum, as a mixture of alloying elements in their natural ratios. After extrusion, two new aluminum alloys with a total percentage of metallic additives ranging from 1 to 6 percent were prepared. The possibilities of the precipitation strengthening of these aluminum alloys, especially those containing Mn, Fe, Si, Ni, and Cu, were investigated under a wide range of heat treatment conditions. After each tested combination of annealing and artificial aging temperatures, the phase composition and the microstructure changes were recorded by X-ray diffraction, optical, and scanning electron microscopy with EDS analysis. Under none of the tested heat treatment conditions is a significant hardening effect observed, even though the precipitate phases are observed by TEM. However, the changes in the morphology of the present intermetallic phases caused by the heat treatment are revealed, which highlights the further possible development of these multicomponent alloys. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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22 pages, 8379 KiB

Open AccessArticle

Effect of Magnesium Powder Application on the Microstructure and Properties of Rods Extruded by the Forward-Backward Rotating Die Extrusion Method

by Anita Olszówka-Myalska, Patryk Wrześniowski, Paweł Ostachowski, Marcin Godzierz and Dariusz Kuc

Materials 2022, 15(12), 4094; https://doi.org/10.3390/ma15124094 - 9 Jun 2022

Cited by 3 | Viewed by 1855

Abstract

The effects of severe plastic deformation (SPD) with a forward-backward rotating die (KOBO extrusion) on pure magnesium, in the form of cold-compacted powder, sintered powder, or cast ingots as reference, were examined. This method is known to reinforce metals, but the role of [...] Read more.

The effects of severe plastic deformation (SPD) with a forward-backward rotating die (KOBO extrusion) on pure magnesium, in the form of cold-compacted powder, sintered powder, or cast ingots as reference, were examined. This method is known to reinforce metals, but the role of the initial form of magnesium applied in the fabrication of metal-based rods, as well as related phenomena, has not been characterized until now. The problem is important in the potential processing of commercial metal powders, the recycling of metal shavings, and the fabrication of metal matrix composites with discontinuous reinforcing phases. In the presented experiments, rods of 8 mm in diameter and 400 mm in length were obtained, and the structural effects induced by KOBO that occurred on a macro- and microscale on the surface and cross sections were characterized. Changes in the size and orientation of α-Mg crystallites were determined by XRD. The porosity, hardness, tensile strength, and compressive strength were measured, and the mechanisms of decohesion dependent on starting metal form were analyzed. After KOBO extrusion, significant differences were observed in the microstructure and properties between the materials derived from cold-compacted powder, sintered powder, and reference cast magnesium. Due to the application of KOBO, apart from α-Mg grain refinement, the MgO derived from the initial powder’s surface was refined to fine regular particles surrounded by magnesium. Their bands curved in the perpendicular plane and were oriented with the extrusion direction of the formed network, which augmented some mechanical properties and changed the decohesion mechanism. The conducted experiments revealed that before extrusion by KOBO, the magnesium powder required sintering under pressure. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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20 pages, 9930 KiB

Open AccessArticle

Dynamic Alloying of Steels in the Super-Deep Penetration Mode

by Yulia Usherenko, Viktors Mironovs, Sergey Usherenko, Vjaceslavs Lapkovskis and Andrei Shishkin

Materials 2022, 15(6), 2280; https://doi.org/10.3390/ma15062280 - 19 Mar 2022

Cited by 3 | Viewed by 1869

Abstract

The dynamic effects observed in collisions represent a specific area of high-energy interaction located at the boundary of mechanics, hydrodynamics, shock wave physics, and alternating high-pressure regions. The paper shows that in the volume of a solid metal body, as a result of [...] Read more.

The dynamic effects observed in collisions represent a specific area of high-energy interaction located at the boundary of mechanics, hydrodynamics, shock wave physics, and alternating high-pressure regions. The paper shows that in the volume of a solid metal body, as a result of dynamic alloying by a high-speed stream of powder particles in the super-deep penetration mode (SDP), fiber structures of altering material arise, forming the framework of the composite material. The stream of powder particles in the metal obstacle following the path of least resistance and the impact of shock waves on particles results in a volumetric framework from the products of interaction between the injected and matrix materials. When using SDP, defective structural elements (channeled)—germs of reinforcing fibers arise. At the subsequent heat treatment, there is an intensive diffusion. The growth process of reinforcing fibers shifts to higher temperatures (as compared to the standard mode), leading to an increase in the bending strength of the fiber material up to 13 times for W6Mo5Cr4V2 high-speed tool steel. As a result of the completion of the growth of reinforcing fibers in the volume of the W6Mo5Cr4V2 high-speed tool steel, the material’s bending strength in 1.2 times is realized. Simultaneously, it provides an increase of wear resistance 1.7–1.8 times. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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18 pages, 11295 KiB

Open AccessArticle

Influence of Asymmetric Rolling Process on the Microstructure Properties of Bimetallic Sheet Metals

by Grzegorz Stradomski, Dariusz Rydz, Tomasz Garstka, Michał Pałęga, Tomasz Dyl, Arkadiusz Szarek, Justyna Łukomska Szarek and Tomasz Dembiczak

Materials 2022, 15(6), 2013; https://doi.org/10.3390/ma15062013 - 9 Mar 2022

Cited by 4 | Viewed by 2522

Abstract

This paper presents the results of research on the determination of the influence of kinetic asymmetry of work rolls on structural changes in hot-rolled bimetallic sheet metals. The tests were conducted on bimetallic samples composed of materials 10CrMo9-10 + X2CrNiMo17-12-2. The scope of [...] Read more.

This paper presents the results of research on the determination of the influence of kinetic asymmetry of work rolls on structural changes in hot-rolled bimetallic sheet metals. The tests were conducted on bimetallic samples composed of materials 10CrMo9-10 + X2CrNiMo17-12-2. The scope of the research included a comparative analysis for two cooling variants: I in water (freezing the structure immediately after rolling) and II for cooling in air. The research conducted showed that the introduction of asymmetric conditions to the rolling process results in a greater grain fragmentation in the so-called hard layer and does not have a negative effect on microstructural changes in the soft layer. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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13 pages, 2665 KiB

Open AccessArticle

Boundary Element and Sensitivity Analysis of Anisotropic Thermoelastic Metal and Alloy Discs with Holes

by Mohamed Abdelsabour Fahmy and Mohammed Owaidh Alsulami

Materials 2022, 15(5), 1828; https://doi.org/10.3390/ma15051828 - 28 Feb 2022

Cited by 18 | Viewed by 1546

Abstract

The main aim of this paper was to develop an advanced processing method for analyzing of anisotropic thermoelastic metal and alloy discs with holes. In the boundary element method (BEM), the heat impact is expressed as an additional volume integral in the corresponding [...] Read more.

The main aim of this paper was to develop an advanced processing method for analyzing of anisotropic thermoelastic metal and alloy discs with holes. In the boundary element method (BEM), the heat impact is expressed as an additional volume integral in the corresponding boundary integral equation. Any attempt to integrate it directly will necessitate domain discretization, which will eliminate the BEM’s most distinguishing feature of boundary discretization. This additional volume integral can be transformed into the boundary by using branch-cut redefinitions to avoid the use of additional line integrals. The numerical results obtained are presented graphically to show the effects of the transient and steady-state heat conduction on the quasi-static thermal stresses of isotropic, orthotropic, and anisotropic metal and alloy discs with holes. The validity of the proposed technique is examined for one-dimensional sensitivity, and excellent agreement with finite element method and experimental results is obtained. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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14 pages, 6089 KiB

Open AccessArticle

Microstructural Evolution and Mechanical Properties of Pure Aluminum upon Multi-Pass Caliber Rolling

by Shulong Guo, Hui Yu, Zhifeng Wang, Wei Yu, Weili Cheng, Lixin Huang, Chunhai Liu, Fuxing Yin, Weimin Zhao and Chunling Qin

Materials 2022, 15(3), 1206; https://doi.org/10.3390/ma15031206 - 5 Feb 2022

Cited by 4 | Viewed by 2276

Abstract

The paper presents the microstructure and mechanical property of pure aluminum (Al) fabricated by multi-pass caliber rolling at room temperature. The finite element modeling (FEM) simulation was performed to explore the changes in rolling force, effective stress and strain, and temperature under various [...] Read more.

The paper presents the microstructure and mechanical property of pure aluminum (Al) fabricated by multi-pass caliber rolling at room temperature. The finite element modeling (FEM) simulation was performed to explore the changes in rolling force, effective stress and strain, and temperature under various rolling passes. As the number of rolling passes increased, the overall temperature, effective stress, and strain gradually increased, while the maximum rolling force decreased. In addition, due to the dynamic recrystallization (DRX), the average grain size reduced from 1 mm to 14 µm with the increase in rolling passes. The dislocation density increased and it gradually evolved into the high-angle grain boundaries (HAGBs). Moreover, the initial cubic texture rotated to the brass component and finally changed to a mixture of Cube and Brass types. The highest tensile yield strength (TYS), ultimate tensile strength (UTS) and elongation (El.) of caliber rolled pure Al (116 MPa, 135 MPa, and 17%, respectively) can be achieved after 13 rolling passes, which mainly attributed to grain refinement. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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12 pages, 9963 KiB

Open AccessArticle

Vacuum Brazing of Metallized YSZ and Crofer Alloy Using 72Ag-28Cu Filler Foil

by Liang-Wei Huang, Ren-Kae Shiue, Chien-Kuo Liu, Yung-Neng Cheng, Ruey-Yi Lee and Leu-Wen Tsay

Materials 2022, 15(3), 939; https://doi.org/10.3390/ma15030939 - 26 Jan 2022

Cited by 2 | Viewed by 2082

Abstract

The study focused on dissimilar brazing of metallized YSZ (Yttria-Stabilized Zirconia) and Crofer alloy using BAg-8 (72Ag-28Cu, wt%) filler foil. The YSZ substrate was metallized by sequentially sputtering Ti (0.5/1 μm), Cu (1/3 μm), and Ag (1.5/5 μm) layers, and the Crofer substrate [...] Read more.

The study focused on dissimilar brazing of metallized YSZ (Yttria-Stabilized Zirconia) and Crofer alloy using BAg-8 (72Ag-28Cu, wt%) filler foil. The YSZ substrate was metallized by sequentially sputtering Ti (0.5/1 μm), Cu (1/3 μm), and Ag (1.5/5 μm) layers, and the Crofer substrate was coated with Ag layers with a thickness of 1.5 and 5 μm, respectively. The BAg-8 filler demonstrated excellent wettability on both metallized YSZ and Crofer substrates. The brazed joint primarily consisted of Ag-Cu eutectic. The metallized Ti layer dissolved into the braze melt, and the Ti preferentially reacted with YSZ and Fe from the Crofer substrate. The globular Fe₂Ti intermetallic compound was observed on the YSZ side of the joint. The interfacial reaction of Ti was increased when the thickness of the metallized Ti layer was increased from 0.5 to 1 μm. Both brazed joints were crack free, and no pressure drop was detected after testing at room temperature for 24 h. In the YSZ/Ti(0.5μ)/Cu(1μ)/Ag(1.5μ)/BAg-8(50μ)/Ag(1.5μ)/Crofer joint tested at 600 °C, the pressure of helium decreased from 2.01 to 1.91 psig. In contrast, the helium pressure of the YSZ/Ti(1μ)/Cu(3μ)/Ag(5μ)/BAg-8(50μ)/Ag(5μ)/Crofer joint slightly decreased from 2.02 to 1.98 psig during the cooling cycle of the test. The greater interfacial reaction between the metallized YSZ and BAg-8 filler due to the thicker metallized Ti layer on the YSZ substrate was responsible for the improved gas-tight performance of the joint. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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20 pages, 7765 KiB

Open AccessArticle

Effect of Thermomechanical Treatment of Al-Zn-Mg-Cu with Minor Amount of Sc and Zr on the Mechanical Properties

by Azam Beigi Kheradmand, Shamseddin Mirdamadi, Zahra Lalegani and Bejan Hamawandi

Materials 2022, 15(2), 589; https://doi.org/10.3390/ma15020589 - 13 Jan 2022

Cited by 9 | Viewed by 2128

Abstract

In this study, the mechanical and microstructural properties of Al-Zn-Mg-Cu-Zr cast alloy with 0.1% Sc under homogeneous, dissolution, and T6 and thermomechanical treatments with the aim of increasing the volume fraction of MgZn₂. Al₃(Sc,Zr) reinforcing precipitates were examined by [...] Read more.

In this study, the mechanical and microstructural properties of Al-Zn-Mg-Cu-Zr cast alloy with 0.1% Sc under homogeneous, dissolution, and T6 and thermomechanical treatments with the aim of increasing the volume fraction of MgZn₂. Al₃(Sc,Zr) reinforcing precipitates were examined by hardness, microscopic examinations, tensile tests and software analysis. The results showed that, firstly, the hardness results are well proportional to the results of the tensile properties of alloys and, secondly, the strength of the alloy with thermomechanical treatments compared to T6 treatments increased from 492 MPa to 620 MPa and the elongation increased from 8% to 17% and was 100% upgraded. Microstructural and fracture cross section investigations showed that Al₃(Sc,Zr) nanosize dispersoids were evenly distributed among MgZn₂ dispersoids and the alloy fracture was of semi-ductile type and nanosize dispersoids less than 10 nm were observed at the end of the dimples in the fracture section. The volume fraction of nanosize dispersoids in the whole microstructure of thermomechanical treatment samples was also much higher than that of T6 heat treated samples, so that the percentage of Al₃(Sc,Zr) precipitates arrived from less than 1% in T6 operation to 8.28% in the quench-controlled thermomechanical operation (with 50% deformation). The quality index (QI) in thermomechanical treatment samples is 19% higher than T6 samples, so that this index has increased from 641 in T6 operation to 760 in samples under thermomechanical treatment due to precipitate morphology, volume fraction of precipitates, their uniform distribution in the matrix, and nano sized precipitates in samples under thermomechanical treatment. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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21 pages, 8111 KiB

Open AccessArticle

Tailoring a Refractory High Entropy Alloy by Powder Metallurgy Process Optimization

by Larissa Moravcikova-Gouvea, Igor Moravcik, Vaclav Pouchly, Zuzana Kovacova, Michael Kitzmantel, Erich Neubauer and Ivo Dlouhy

Materials 2021, 14(19), 5796; https://doi.org/10.3390/ma14195796 - 3 Oct 2021

Cited by 19 | Viewed by 2635

Abstract

This paper reports the microstructural evolution and mechanical properties of a low-density Al_0.3NbTa_0.8Ti_1.5V_0.2Zr refractory high-entropy alloy (RHEA) prepared by means of a combination of mechanical alloying and spark plasma sintering (SPS). Prior to sintering, the [...] Read more.

This paper reports the microstructural evolution and mechanical properties of a low-density Al_0.3NbTa_0.8Ti_1.5V_0.2Zr refractory high-entropy alloy (RHEA) prepared by means of a combination of mechanical alloying and spark plasma sintering (SPS). Prior to sintering, the morphology, chemical homogeneity and crystal structures of the powders were thoroughly investigated by varying the milling times to find optimal conditions for densification. The sintered bulk RHEAs were produced with diverse feedstock powder conditions. The microstructural development of the materials was analyzed in terms of phase composition and constitution, chemical homogeneity, and crystallographic properties. Hardness and elastic constants also were measured. The calculation of phase diagrams (CALPHAD) was performed to predict the phase changes in the alloy, and the results were compared with the experiments. Milling time seems to play a significant role in the contamination level of the sintered materials. Even though a protective atmosphere was used in the entire manufacturing process, carbide formation was detected in the sintered bulks as early as after 3 h of powder milling. Oxides were observed after 30 h due to wear of the high-carbon steel milling media and SPS consolidation. Ten hours of milling seems sufficient for achieving an optimal equilibrium between microstructural homogeneity and refinement, high hardness and minimal contamination. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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17 pages, 6330 KiB

Open AccessArticle

Microstructural Evolution of a 3003 Based Aluminium Alloy during the CSET Process

by Orsolya Molnárová, Stanislav Habr, Esther de Prado, Jaroslav Čapek, Ondřej Ekrt, Gergely Németh, Přemysl Málek and Pavel Lejček

Materials 2021, 14(19), 5770; https://doi.org/10.3390/ma14195770 - 2 Oct 2021

Cited by 4 | Viewed by 2011

Abstract

A new severe plastic deformation technique, known as the complex shearing of extruded tube (CSET), was applied to a 3003 based model aluminium alloy. This technique, consisting of a combination of extrusion and two consecutive Equal Chanel Angular Pressing (ECAP) passes accompanied with [...] Read more.

A new severe plastic deformation technique, known as the complex shearing of extruded tube (CSET), was applied to a 3003 based model aluminium alloy. This technique, consisting of a combination of extrusion and two consecutive Equal Chanel Angular Pressing (ECAP) passes accompanied with concurrent torsional straining, is capable to produce a fine-grained tubular sample directly from a bulk metallic cylinder in one forming operation. In the present paper, the microstructural development of the alloy during partial processes of CSET was studied in detail using light microscopy, electron backscatter diffraction, and transmission electron microscopy. It was found that CSET technique refines the grain size down to 0.4 µm and, consequently, increases the microhardness from the initial value of 40 HV to the final value of 120 HV. The contributions of partial processes of CSET to the total strain were estimated. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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9 pages, 62913 KiB

Open AccessArticle

Enhanced Grain Refinement and Precipitation of the IEECAPed Mg-Sm-Zn-Zr Alloy by Nd Addition

by Kun Liu, Sicong Zhao, Changliang Wang, Liping Wang, Yicheng Feng, Dongrong Liu, Jingfang Li and Zhiwei Wang

Materials 2021, 14(19), 5667; https://doi.org/10.3390/ma14195667 - 29 Sep 2021

Cited by 6 | Viewed by 1774

Abstract

Achieving magnesium-rare earth alloys with excellent mechanical properties remains a challenging goal in the aerospace industry. The integrated extrusion and equal channel angular pressing were employed to refine grain and improve the mechanical properties of Mg-xNd-2.0Sm-0.4Zn-0.4Zr alloys. The effect of Nd element on [...] Read more.

Achieving magnesium-rare earth alloys with excellent mechanical properties remains a challenging goal in the aerospace industry. The integrated extrusion and equal channel angular pressing were employed to refine grain and improve the mechanical properties of Mg-xNd-2.0Sm-0.4Zn-0.4Zr alloys. The effect of Nd element on microstructure and mechanical properties of the extruded and subsequently aged alloys were carried out by varying the amount of the Nd element from 0 wt.% to 2.5 wt.%. The optical microscopy results indicated that the grain size was remarkably refined by the addition of Nd element. The grain size decreased from 29.7 μm to 10.9 μm with increasing of the Nd element from 0 wt.% to 2.5 wt.%. The transmission electron microscopy results showed that the nano-scaled basal lamellar precipitates, prismatic lamellar precipitates and granular precipitates were formed in α-Mg matrix. The amount of the precipitates increased significantly by the addition of Nd. Moreover, the strength of the alloys significantly improved with Nd. Superior strength and considerable plasticity were obtained as the content of Nd element reached 2.0 wt.%, while the tensile strength of the Mg-2.0Nd-Sm-Zn-Zr alloy (315 ± 5 MPa) increased by 35.8% with respect to the Nd-free alloy (232 ± 3 MPa). Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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