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Metals
Volume 8
Issue 12
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Metals, Volume 8, Issue 12 (December 2018) – 111 articles

Cover Story (view full-size image): The numerical modeling process of sheet metal forming is performed on fully coupled damage constitutive equations and the remeshing procedure. Based on CDM, an isotropic damage model coupled with the Johnson–Cook flow law is proposed to satisfy the thermodynamic and damage requirements. A 3D adaptive remeshing scheme using linear tetrahedral FE is developed in order to simulate the large plastic deformations and crack propagation that occur after damage. Four examples are proposed to prove that the numerical methodology is an advanced and reliable tool to simulate various sheet metal forming processes in order to avoid damage in incremental forming, deep-drawing, and multi-point drawing, or to enhance damage in cutting operations. The quantitative effects of damage and remeshing on the metal forming are studied, and a qualitative comparison with some available experimental data is given. View this [...] Read more.
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12 pages, 4564 KiB  
Article
Effects of Microstructure and Texture Evolution on Strength Improvement of an Extruded Mg-10Gd-2Y-0.5Zn-0.3Zr Alloy
by Zhiyong Xue, Xiuzhu Han, Zhiyong Zhou, Yanlin Wang, Xuesong Li and Jiapeng Wu
Metals 2018, 8(12), 1087; https://doi.org/10.3390/met8121087 - 19 Dec 2018
Cited by 6 | Viewed by 3014
Abstract
The extrusion process with a large extrusion ratio (36:1) has a great effect on microstructure refinement and strength improvement of the Mg-10Gd-2Y-0.5Zn-0.3Zr alloy. The tensile yield strength, ultimate tensile strength, and elongation of the extruded alloy are 306MPa, 410MPa, and 16.3%, respectively. The [...] Read more.
The extrusion process with a large extrusion ratio (36:1) has a great effect on microstructure refinement and strength improvement of the Mg-10Gd-2Y-0.5Zn-0.3Zr alloy. The tensile yield strength, ultimate tensile strength, and elongation of the extruded alloy are 306MPa, 410MPa, and 16.3%, respectively. The causes of strength improvement of the extruded alloy are discussed in detail. The grain refinement is a main strengthening source, contributing ~67MPa to the tensile yield strength of the extruded alloy. Dense precipitation of long period stacking ordered (LPSO) and β′ phases on the matrix and transformation of texture type in the extrusion process also partly increase the strength. In addition, a small number of {10 1 ¯ 2} twins during tensile test is another factor improving the strength of the extruded alloy. Full article
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13 pages, 7519 KiB  
Article
Microwave Sintering of Ti6Al4V: Optimization of Processing Parameters for Maximal Tensile Strength and Minimal Pore Size
by Dilpreet Singh, Abhishek Rana, Pawan Sharma, Pulak Mohan Pandey and Dinesh Kalyanasundaram
Metals 2018, 8(12), 1086; https://doi.org/10.3390/met8121086 - 19 Dec 2018
Cited by 11 | Viewed by 4212
Abstract
Pressureless sintering is a powder metallurgical process wherein the powder particles are sintered without the aid of any compressive force. Though this additive manufacturing process is economical, the strength of the component is undermined due to the presence of pores; the elimination of [...] Read more.
Pressureless sintering is a powder metallurgical process wherein the powder particles are sintered without the aid of any compressive force. Though this additive manufacturing process is economical, the strength of the component is undermined due to the presence of pores; the elimination of which is a challenge. In this work, the optimal process parameters for the pressureless microwave sintering of a grade 5 titanium alloy that yields higher tensile strength and minimum sizes of pores were obtained. The three process parameters (sintering temperature, heating rate, and holding time) were experimented at five different levels using the design of experiments (DOE). Post sintering, the tensile strength was assessed as per ASTM standard B925-15, while the pore size was evaluated, non-destructively, using micro-computed tomography (µ-CT). The optimal process parameters that yielded minimum size pores were: sintering temperature—1293 °C, heating rate—6.65 °C/min; and holding time—72 min. Full article
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14 pages, 1732 KiB  
Review
Measuring Structural Heterogeneities in Metallic Glasses Using Transmission Electron Microscopy
by Lin Tian and Cynthia A. Volkert
Metals 2018, 8(12), 1085; https://doi.org/10.3390/met8121085 - 19 Dec 2018
Cited by 10 | Viewed by 4815
Abstract
Local heterogeneities in the structure and properties of metallic glasses have recently been predicted by computer simulations and also observed in experiments. These heterogeneities are important in understanding the stability and performance of metallic glasses. Progress has been made in measuring heterogeneities in [...] Read more.
Local heterogeneities in the structure and properties of metallic glasses have recently been predicted by computer simulations and also observed in experiments. These heterogeneities are important in understanding the stability and performance of metallic glasses. Progress has been made in measuring heterogeneities in elastic properties and local density down to length scales of less than 10 nm. In this review, we focus on studies of structural and mechanical heterogeneities with emphasis on those achieved by transmission electron microscopy which has an excellent spatial resolution, multifunctional detection modes, as well as in-situ testing capabilities. We argue that the next important step in understanding the behavior of metallic glasses lies in understanding the spatial and temporal correlations between the various structural and mechanical heterogeneities. Full article
(This article belongs to the Special Issue Metallic Glasses: Pathways to Viable Applications)
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9 pages, 5891 KiB  
Article
Thermal Behavior of Hydrated Iron Sulfate in Various Atmospheres
by Ndue Kanari, Nour-Eddine Menad, Etleva Ostrosi, Seit Shallari, Frederic Diot, Eric Allain and Jacques Yvon
Metals 2018, 8(12), 1084; https://doi.org/10.3390/met8121084 - 19 Dec 2018
Cited by 36 | Viewed by 9311
Abstract
Iron sulfate, in particular FeSO4·7H2O, is derived from titanium dioxide production and the steel pickling process. Regarding TiO2 manufacturing, the amount of the resultant FeSO4·7H2O can be as high as 6 tons per ton [...] Read more.
Iron sulfate, in particular FeSO4·7H2O, is derived from titanium dioxide production and the steel pickling process. Regarding TiO2 manufacturing, the amount of the resultant FeSO4·7H2O can be as high as 6 tons per ton of produced TiO2, leading to a huge amount of ferrous sulfate heptahydrate, which is considered an environmental and economic concern for the titanium dioxide industry in European countries. The present paper focuses on the thermal treatment of ferrous sulfate (heptahydrate and monohydrate) samples under different conditions. Nonisothermal thermogravimetric (TG) analysis was used to study the behavior of iron sulfate samples at temperatures of up to 1000 °C in Cl2 + O2, O2, and N2 atmospheres. Results showed that the dehydration of iron sulfate heptahydrate in nitrogen started at room temperature and resulted in iron sulfate tetrahydrate (FeSO4·4H2O). The ferrous sulfate monohydrate (FeSO4·H2O) was formed at temperatures close to 150 °C, while the anhydrous ferrous sulfate (FeSO4) was obtained when the samples were heated in nitrogen at over 225 °C. The kinetic features of FeSO4 decomposition into Fe2O3 were revealed under isothermal conditions at temperatures ranging from 500 to 575 °C. The decomposition of iron sulfate was characterized by an apparent activation energy of around 250 kJ/mol, indicating a significant temperature effect on the decomposition process. The obtained powder iron oxide could be directed to the agglomeration unit of iron and the steelmaking process. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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27 pages, 3444 KiB  
Article
A Further Evaluation of the Coupling Relationship between Dephosphorization and Desulfurization Abilities or Potentials for CaO-based Slags: Influence of Slag Chemical Composition
by Xue-min Yang, Jin-yan Li, Meng Zhang, Fang-jia Yan, Dong-ping Duan and Jian Zhang
Metals 2018, 8(12), 1083; https://doi.org/10.3390/met8121083 - 19 Dec 2018
Cited by 11 | Viewed by 3276
Abstract
The coupling relationships between dephosphorization and desulfurization abilities or potentials for CaO–FeO–Fe2O3–Al2O3–P2O5 slags over a large variation range of slag oxidization ability during the secondary refining process of molten steel have been [...] Read more.
The coupling relationships between dephosphorization and desulfurization abilities or potentials for CaO–FeO–Fe2O3–Al2O3–P2O5 slags over a large variation range of slag oxidization ability during the secondary refining process of molten steel have been proposed by the present authors as log L P + 5 log L S or log C PO 4 3 − + log C S 2 − in the reducing zone and as log L P + log L S − 5 log N Fe t O or log C PO 4 3 − + log C S 2 − − log N FeO in the oxidizing zone based on the ion and molecule coexistence theory (IMCT). In order to further verify the validation and feasibility of the proposed coupling relationships, the effects of chemical composition of the CaO-based slags are provided. The chemical composition of slags was described by three group parameters including reaction abilities of components represented by the mass action concentrations N i , two kinds of slag basicity as simplified complex basicity ( %   CaO ) / [ ( %   P 2 O 5 ) + ( %   Al 2 O 3 ) ] and optical basicity Λ , and the comprehensive effect of iron oxides FetO and basic oxide CaO. Comparing with the strong effects of chemical composition of the CaO-based slags on dephosphorization and desulfurization abilities or potentials, the proposed coupling relationships have been confirmed to not only be independent of slag oxidization ability as expected but also irrelevant to the aforementioned three groups of parameters for representing the chemical composition of the CaO-based slags. Increasing temperature from 1811 to 1927 K (1538 to 1654 °C) can result in a decreasing tendency of the proposed coupling relationships. In terms of the proposed coupling relationships, chemical composition of slags or fluxes with assigned dephosphorization ability or potential can be theoretically designed or optimized from its desulfurization ability or potential, and vice versa. Considering the large difference of magnitude between phosphate capacity C PO 4 3 − and sulfide capacity C S 2 − , the proposed coupling relationships between dephosphorization and desulfurization abilities for CaO-based slags are recommended to design or optimize chemical composition of slags. Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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14 pages, 7225 KiB  
Article
Petrological Study of Ferrous Burden-Crucible Interaction in Softening & Melting Experiments: Implications for the Relevance of Pressure Drop Measurements
by James Small, Allert Adema, Kirill Andreev and Enno Zinngrebe
Metals 2018, 8(12), 1082; https://doi.org/10.3390/met8121082 - 19 Dec 2018
Cited by 6 | Viewed by 3531
Abstract
Numerous tests are used worldwide to investigate the advanced high temperature reduction, softening, and melting (S&M) of blast furnace ferrous burden material. Commonly, the curve of pressure drop (dP) against temperature, measured over the experimental charge, is taken as directly indicative of the [...] Read more.
Numerous tests are used worldwide to investigate the advanced high temperature reduction, softening, and melting (S&M) of blast furnace ferrous burden material. Commonly, the curve of pressure drop (dP) against temperature, measured over the experimental charge, is taken as directly indicative of the evolution of ferrous layer permeability. Previous authors have expressed concerns about the reproducibility and practical relevance of dP measurements due to narrow crucible diameter and wall effects. Petrological study of samples from interrupted Advanced Softening and Melting (ASAM) experiments, performed with ferrous burdens comprising a mixture of pellets (C/S 0.1–0.7) and highly basic sinter (C/S 2.4–3.5), sheds light on the nature and controlling mechanisms of systematic artefacts influencing the measurement of dP. The observations imply that the dP-T curves in ASAM, and likely other similar S&M, tests most immediately reflect the varying ease of gas flow in a sidewall bypass around the qualitatively impermeable ferrous burden layer, rather than through it. This is controlled by the formation of diverse oxide(-slag)-metal segregations at the exterior of the ferrous burden layer. The potential correlation of parameters derived from dP measurements with input burden characteristics is not in itself sufficient evidence that the measurements are indicative of the ferrous layer permeability. Full article
(This article belongs to the Special Issue Selected Papers from 8th ICSTI 2018)
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13 pages, 2880 KiB  
Article
Hydrogen Interaction with Deep Surface Modified Zr-1Nb Alloy by High Intensity Ti Ion Implantation
by Egor B. Kashkarov, Alexander I. Ryabchikov, Alexander V. Kurochkin, Maxim S. Syrtanov, Alexey E. Shevelev, Aleksei Obrosov and Sabine Weiß
Metals 2018, 8(12), 1081; https://doi.org/10.3390/met8121081 - 19 Dec 2018
Cited by 4 | Viewed by 3729
Abstract
A deep surface modified TiZr layer was fabricated by high-intensity low-energy titanium ion implantation into zirconium alloy Zr-1Nb. Gas-phase hydrogenation was performed to evaluate protective properties of the modified layer against hydrogen permeation into Zr-1Nb alloy. The effects of ion implantation and hydrogen [...] Read more.
A deep surface modified TiZr layer was fabricated by high-intensity low-energy titanium ion implantation into zirconium alloy Zr-1Nb. Gas-phase hydrogenation was performed to evaluate protective properties of the modified layer against hydrogen permeation into Zr-1Nb alloy. The effects of ion implantation and hydrogen on microstructure, phase composition and elemental distribution of TiZr layer were analyzed by scanning electron microscopy, X-ray diffraction, and glow-discharge optical emission spectroscopy, respectively. It was revealed that TiZr layer (~10 μm thickness) is represented by α′ + α(TiZr) lamellar microstructure with gradient distribution of Ti through the layer depth. It was shown that the formation of TiZr layer provides significant reduction of hydrogen uptake by zirconium alloy at 400 and 500 °C. Hydrogenation of the modified layer leads to refinement of lamellar plates and formation of more homogenous microstructure. Hydrogen desorption from Ti-implanted Zr-1Nb alloy was analyzed by thermal desorption spectroscopy. Hydrogen interaction with the surface modified TiZr layer, as well as its resistance properties, are discussed. Full article
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22 pages, 9978 KiB  
Review
A Review on the Advancement of Ternary Alloy Counter Electrodes for Use in Dye-Sensitised Solar Cells
by Edson Meyer, Raymond Taziwa, Dorcas Mutukwa and Nyengerai Zingwe
Metals 2018, 8(12), 1080; https://doi.org/10.3390/met8121080 - 19 Dec 2018
Cited by 15 | Viewed by 5189
Abstract
A dye-sensitised solar cell (DSSC) counter electrode (CE) plays a vital role in catalysing the conversion of triiodide ( I 3 − ) to iodide ions ( I − ), thereby ensuring the completion of the repetitive cycle of electricity generation. The platinum [...] Read more.
A dye-sensitised solar cell (DSSC) counter electrode (CE) plays a vital role in catalysing the conversion of triiodide ( I 3 − ) to iodide ions ( I − ), thereby ensuring the completion of the repetitive cycle of electricity generation. The platinum CE, despite being the standard counter electrode in DSSCs, has drawbacks of platinum’s rarity and high cost. Platinum is an excellent redox catalyst, and consequently, it is the most sought-after metal for catalytic conversions. The huge demand for platinum in the automotive industry for vehicular catalytic converters, the pharmaceutical industry, and in oil refining, as well as other industries, has driven its price to unprecedented levels. The prohibitive price of platinum has caused newer thin film technologies, such as the DSSC which depends on the platinum CE, to be cost-ineffective, thus meaning they cannot compete with the better-established silicon-based solar cells. These problems have stagnated the development of the DSSC, which in turn has dampened larger commercialisation prospects for this thin film technology. With this in mind, this review paper focuses on recent progress in the research and development of alternative cost-effective materials to replace Pt-based CEs. Ternary alloys are amongst the possible alternatives that have been explored, yielding varied results. Alloys, especially ternary sulphides, selenides, and oxides, are attractive as alternatives as they are cheap and are easily fabricated. Ternary alloys also have a synergistic effect produced by the coexistence of two metal ions in a crystal structure, which is believed to induce greater catalytic capability, thus making them ideal cost-effective materials to replace the Pt CE in DSSCs. This review intends to highlight the performance of ternary alloy counter electrodes through the analysis of charge transfer resistance and power conversion efficiencies. Focus is also given to the restrictions and impediments to the attainment of higher power conversion efficiency in alternative CEs. The advances in fabrication of simple ternary alloys, as well as more advanced hierarchical nanostructured counter electrodes, are discussed here in detail. Results obtained to date indicate that the efficiencies of ternary alloy counter electrodes are still below that of the platinum counter electrode, and hence more research is required to enhance their efficiencies. Full article
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11 pages, 4271 KiB  
Article
Microstructure Evolution in ODS Alloys with a High-Volume Fraction of Nano Oxides
by Jiří Svoboda, Vít Horník, Luděk Stratil, Hynek Hadraba, Bohuslav Mašek, Omid Khalaj and Hana Jirková
Metals 2018, 8(12), 1079; https://doi.org/10.3390/met8121079 - 19 Dec 2018
Cited by 31 | Viewed by 3953
Abstract
Existing oxide dispersion strengthened (ODS) alloys are, besides Ni-based superalloy single crystals, the most creep-resistant materials. The creep resistance of the ODS alloys may, moreover, be significantly improved thanks to increasing the volume fraction of the nano oxides by more than one order [...] Read more.
Existing oxide dispersion strengthened (ODS) alloys are, besides Ni-based superalloy single crystals, the most creep-resistant materials. The creep resistance of the ODS alloys may, moreover, be significantly improved thanks to increasing the volume fraction of the nano oxides by more than one order of magnitude so that the oxides play a decisive role in strengthening. The present experimental study deals with two systems of such a high-volume fraction of nano oxides, namely, the Fe-11Al-1O and Fe-17Cr-7Al-4Y2O3 systems prepared by mechanical alloying and hot rolling leading to a rather stable fine-grained microstructure. This microstructure undergoes static recrystallization at high temperatures. The kinetics of static recrystallization and coarsening of nano oxides in recrystallized grains is determined for both systems. The difference in kinetics of coarsening of Al-based and Y-based oxides in the Fe-11Al-1O and Fe-17Cr-7Al-4Y2O3 systems is expressive and predetermines the Fe-17Cr-7Al-4Y2O3 system or similar ones to become the new leading system among creep- and oxidation-resistant materials for applications up to 1200 °C. Full article
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9 pages, 3113 KiB  
Article
Dissolution of Scrap in Hot Metal under Linz–Donawitz (LD) Steelmaking Conditions
by Florian Markus Penz, Johannes Schenk, Rainer Ammer, Gerald Klösch and Krzysztof Pastucha
Metals 2018, 8(12), 1078; https://doi.org/10.3390/met8121078 - 19 Dec 2018
Cited by 14 | Viewed by 5545
Abstract
One of the main charging materials of the Linz–Donawitz oxygen steelmaking process (LD) is scrap. Scrap acts as a coolant for the exothermic reactions inside the LD vessel and as an iron source in addition to hot metal. The optimization of the LD [...] Read more.
One of the main charging materials of the Linz–Donawitz oxygen steelmaking process (LD) is scrap. Scrap acts as a coolant for the exothermic reactions inside the LD vessel and as an iron source in addition to hot metal. The optimization of the LD process is focused, amongst other factors, on thermodynamic and kinetic modelling. The results of simulations have to be validated in close to reality laboratory-scale experiments. A study was made on the dissolution behavior of common steel scrap in carbon-saturated hot metal which is charged into LD converters. In order to examine the effect of several parameters on diffusive scrap melting, the difference between stagnant and dynamic dissolution as well as the influence of the hot metal temperature were investigated. Using a literature-based equation the mass transfer coefficient of carbon between the solid scrap and the liquid hot metal was evaluated. The ranges of values of the ablation rate and the mass transfer coefficient for the appropriate systems are pointed out, resulting in a significant dependence of the investigated parameters. Full article
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12 pages, 40056 KiB  
Article
Porosity Characteristics and Effect on Tensile Shear Strength of High-Strength Galvanized Steel Sheets after the Gas Metal Arc Welding Process
by Seungmin Shin and Sehun Rhee
Metals 2018, 8(12), 1077; https://doi.org/10.3390/met8121077 - 18 Dec 2018
Cited by 9 | Viewed by 5112
Abstract
In this study, lap joint experiments were conducted using galvanized high-strength steel, SGAFH 590 FB 2.3 mmt, which was applied to automotive chassis components in the gas metal arc welding (GMAW) process. Zinc residues were confirmed using a semi-quantitative energy dispersive X-ray spectroscopy [...] Read more.
In this study, lap joint experiments were conducted using galvanized high-strength steel, SGAFH 590 FB 2.3 mmt, which was applied to automotive chassis components in the gas metal arc welding (GMAW) process. Zinc residues were confirmed using a semi-quantitative energy dispersive X-ray spectroscopy (EDS) analysis of the porosity in the weld. In addition, a tensile shear test was performed to evaluate the weldability. Furthermore, the effect of porosity defects, such as blowholes and pits generated in the weld, on the tensile shear strength was experimentally verified by comparing the porosity at the weld section of the tensile test specimen with that measured through radiographic testing. Full article
(This article belongs to the Special Issue Joining of Advanced High Strength Steels for the Automotive Industry)
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18 pages, 5491 KiB  
Article
Hydrophobic and Corrosion Behavior of Sol-Gel Hybrid Coatings Based on the Combination of TiO2 NPs and Fluorinated Chains for Aluminum Alloys Protection
by Pedro J. Rivero, Juan Deyo Maeztu, Calos Berlanga, Adrian Miguel, José F. Palacio and Rafael Rodriguez
Metals 2018, 8(12), 1076; https://doi.org/10.3390/met8121076 - 18 Dec 2018
Cited by 22 | Viewed by 4710
Abstract
In this work, layers of a sol-gel hybrid matrix doped with metal oxide nanoparticles (TiO2 NPs) have been deposited on flat samples of AA6061-T6 aluminum alloy using the dip-coating technique, with the aim of obtaining coatings with better anti-corrosive and hydrophobic properties. [...] Read more.
In this work, layers of a sol-gel hybrid matrix doped with metal oxide nanoparticles (TiO2 NPs) have been deposited on flat samples of AA6061-T6 aluminum alloy using the dip-coating technique, with the aim of obtaining coatings with better anti-corrosive and hydrophobic properties. Two different organic modified silica alkoxides, namely 3-(glycidyloxypropyl)trimethoxysilane (GPTMS) and methyltriethoxysilane (MTEOS), have been used for an adequate entrapment of the metal oxide nanoparticles. In addition, a fluorinated metal-alkoxide precursor has also been added to the hybrid matrix in order to improve the hydrophobic behavior. The experimental results corroborate that the presence of these TiO2 NPs play an important role in the development of the sol-gel hybrid coatings. The water contact angle (WCA) measurements, as well as pencil hardness tests indicate that TiO2 NPs make a considerable increase in the resultant hydrophobicity possible, with better mechanical properties of the coatings. The coating thickness has been measured by cross-section scanning electron microscopy (SEM). In addition, a glow discharge optical emission spectroscopy (GD-OES) analysis has been carried out in order to corroborate the adequate entrapment of the TiO2 NPs into the sol-gel coatings. Finally, potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) have been performed in order to evaluate the corrosion resistance of the coatings. All the results provide insights into the efficacy of the developed sol-gel hybrid coatings for anticorrosive purposes with good mechanical properties. Full article
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12 pages, 3175 KiB  
Article
Mechanism of {332}<113> Twinning Formation in Cold-Rolled Ti-Nb-Ta-Zr-O Alloy
by Jinhui Sun and Leng Chen
Metals 2018, 8(12), 1075; https://doi.org/10.3390/met8121075 - 18 Dec 2018
Cited by 1 | Viewed by 2705
Abstract
In this study, the mechanism of {332}<113> twinning formation in cold-rolled Ti-35Nb-2Ta-3Zr-O (wt %) alloy was investigated based on the Taylor-Bishop-Hill theory. The experimental data of crystal orientation in the rolling bite zone was obtained via electron back-scattered diffraction (EBSD). The deformation energy [...] Read more.
In this study, the mechanism of {332}<113> twinning formation in cold-rolled Ti-35Nb-2Ta-3Zr-O (wt %) alloy was investigated based on the Taylor-Bishop-Hill theory. The experimental data of crystal orientation in the rolling bite zone was obtained via electron back-scattered diffraction (EBSD). The deformation energy of {332}<113> twinning in the propagation stage was calculated using data from EBSD in terms of the Hall-Petch-type relation. The calculation results revealed that the mechanism of {332}<113> twinning formation in β-type Ti-35Nb-2Ta-3Zr-O (wt %) alloy contained two valid models, namely the shear-shuffle model and α″-assisted twinning model. This can help to clarify the mechanism of {332}<113> twinning formation further. Full article
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17 pages, 9933 KiB  
Article
Microstructural and Corrosion Properties of Cold Rolled Laser Welded UNS S32750 Duplex Stainless Steel
by Claudio Gennari, Mattia Lago, Balint Bögre, Istvan Meszaros, Irene Calliari and Luca Pezzato
Metals 2018, 8(12), 1074; https://doi.org/10.3390/met8121074 - 18 Dec 2018
Cited by 39 | Viewed by 4592
Abstract
The main goal of this work was to study the effect of plastic deformation on weldability of duplex stainless steel (DSS). It is well known that plastic deformation prior to thermal cycles can enhance secondary phase precipitation in DSS which can lead to [...] Read more.
The main goal of this work was to study the effect of plastic deformation on weldability of duplex stainless steel (DSS). It is well known that plastic deformation prior to thermal cycles can enhance secondary phase precipitation in DSS which can lead to significant change of the ferrite-austenite phase ratio. From this point of view one of the most important phase transformation in DSS is the eutectoid decomposition of ferrite. Duplex stainless steels (DSSs) are a category of stainless steels which are employed in all kinds of applications where high strength and excellent corrosion resistance are both required. This favorable combination of properties is provided by their biphasic microstructure, consisting of ferrite and austenite in approximately equal volume fractions. Nevertheless, these materials may suffer from several microstructural transformations if they undergo heat treatments, welding processes or thermal cycles. These transformations modify the balanced phase ratio, compromising the corrosion and mechanical properties of the material. In this paper, the microstructural stability as a consequence of heat history due to welding processes has been investigated for a super duplex stainless steel (SDSS) UNS S32750. During this work, the effects of laser beam welding on cold rolled UNS S32750 SDSS have been investigated. Samples have been cold rolled at different thickness reduction (ε = 9.6%, 21.1%, 29.6%, 39.4%, 49.5%, and 60.3%) and then welded using Nd:YAG laser. Optical and electronical microscopy, eddy’s current tests, microhardness tests, and critical pitting temperature tests have been performed on the welded samples to analyze the microstructure, ferrite content, hardness, and corrosion resistance. Results show that laser welded joints had a strongly unbalanced microstructure, mostly consisting of ferritic phase (~60%). Ferrite content decreases with increasing distance from the middle of the joint. The heat-affected zone (HAZ) was almost undetectable and no defects or secondary phases have been observed. Both hardness and corrosion susceptibility of the joints increase. Plastic deformation had no effects on microstructure, hardness or corrosion resistance of the joints, but resulted in higher hardness of the base material. Cold rolling process instead, influences the corrosion resistance of the base material. Full article
(This article belongs to the Special Issue Manufacturing and Application of Stainless Steels)
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17 pages, 7143 KiB  
Article
Experimental and Numerical Investigations into the Failure Mechanisms of TRIP700 Steel Sheets
by Niloufar Habibi, Veera Sundararaghavan, Ulrich Prahl and Ali Ramazani
Metals 2018, 8(12), 1073; https://doi.org/10.3390/met8121073 - 17 Dec 2018
Cited by 10 | Viewed by 4007
Abstract
The formability and failure behavior of transformation-induced plasticity (TRIP) steel blanks were investigated through various stress states. The forming limit diagram (FLD) at fracture was constructed both experimentally and numerically. Numerical studies were performed to evaluate the applicability of different damage criteria in [...] Read more.
The formability and failure behavior of transformation-induced plasticity (TRIP) steel blanks were investigated through various stress states. The forming limit diagram (FLD) at fracture was constructed both experimentally and numerically. Numerical studies were performed to evaluate the applicability of different damage criteria in predicting the FLD as well as complex cross-die deep drawing process. The fracture surface and numerical results reveal that the material failed in a different mode for different strain path. Therefore, the Tresca model, which is based on shear stress, accurately predicted the conditions where shear had a profound effect on the damage initiation, whereas Situ localized necking criterion could calculate the conditions in which localization was dominant. Full article
(This article belongs to the Special Issue Microstructure based Modeling of Metallic Materials)
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14 pages, 17979 KiB  
Article
The Effect of Normalizing Temperature on the Short-Term Creep Rupture of the Simulated HAZ in Gr.91 Steel Welds
by Hao-Wei Wu, Tai-Jung Wu, Ren-Kae Shiue and Leu-Wen Tsay
Metals 2018, 8(12), 1072; https://doi.org/10.3390/met8121072 - 16 Dec 2018
Cited by 6 | Viewed by 3373
Abstract
As-received Gr.91 steel tube was normalized at either 940 or 1060 °C for 1 h, followed by Ar-assisted cooling to room temperature, then tempered at 760 °C for 2 h. Those samples were designated as 940NT or 1060NT samples. An infrared heating system [...] Read more.
As-received Gr.91 steel tube was normalized at either 940 or 1060 °C for 1 h, followed by Ar-assisted cooling to room temperature, then tempered at 760 °C for 2 h. Those samples were designated as 940NT or 1060NT samples. An infrared heating system was used to simulate HAZ microstructures in the weld, which included over-tempering (OT) and partial transformation (PT) zones. The results of short-term creep tests showed that normalizing at higher temperature improved the creep resistance of the Gr.91 steel. By contrast, welding thermal cycles would shorten the creep life of the Gr.91 steel. Among the tested samples in each group, the PT samples had the shortest life to rupture, especially the 940NT-PT sample. The microstructures of the PT samples comprised of fine lath martensite and ferrite subgrains with carbides decorating the grain and subgrain boundaries. Excessive dislocation recovery, rapid coalescence of refined martensite laths, and growth of ferrite subgrains were responsible for the poorer creep resistance of the PT samples relative to those of the other samples. Full article
(This article belongs to the Special Issue Creep and High Temperature Deformation of Metals and Alloys)
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12 pages, 2930 KiB  
Article
Sliding Wear Behavior of Friction Couples Primarily Selected for Corrosion Resistance: Iron Boride/Iron Boride and Iron Boride/Yttria-Stabilized Zirconia
by Pierre D’Ans and Marc Degrez
Metals 2018, 8(12), 1071; https://doi.org/10.3390/met8121071 - 16 Dec 2018
Cited by 2 | Viewed by 3770
Abstract
Wear mitigation in a sliding couple is challenging if wear has to be minimized on both surfaces. In this paper, ball-on-disk testing is performed on sliding couples where both surfaces (ball and disk) are treated for wear resistance. Studied materials are pack borided [...] Read more.
Wear mitigation in a sliding couple is challenging if wear has to be minimized on both surfaces. In this paper, ball-on-disk testing is performed on sliding couples where both surfaces (ball and disk) are treated for wear resistance. Studied materials are pack borided H13 tool steel (ASTM A681), pack borided AISI 420 stainless steel (ASTM A276) and plasma sprayed yttria-stabilized zirconia (YSZ). Borided H13 steel exhibits a single phase Fe2B layer, while AISI 420 has a double phase layer, with FeB on the outer surface. Both FeB/Fe2B and FeB/YSZ couples generate three-body abrasion. In the latter case, mass transfer occurs from the ball to the disk as well. Friction coefficient is ~0.6 for the AISI 420/Fe2B and FeB/Fe2B sliding pairs, with less vibration on the latter and wear rates close to 10−3 mm³·(N·m)−1 for both the ball and the disk. In comparison, the FeB/YSZ pair has a friction coefficient of ~0.65, a similar total mass loss, but a much higher wear rate for YSZ than for FeB. Full article
(This article belongs to the Special Issue Post-Processing Improvements for Mechanical, Microstructure, and Surface Properties of Steel)
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12 pages, 1810 KiB  
Article
Activated Carbon-Spinels Composites for Waste Water Treatment
by Ernesto De la Torre, Ana Belén Lozada, Maricarmen Adatty and Sebastián Gámez
Metals 2018, 8(12), 1070; https://doi.org/10.3390/met8121070 - 16 Dec 2018
Cited by 8 | Viewed by 4660
Abstract
Nowadays, mining effluents have several contaminants that produce great damage to the environment, cyanide chief among them. Ferrites synthesized from transition metals have oxidative properties that can be used for cyanide oxidation due to their low solubility. In this study, cobalt and copper [...] Read more.
Nowadays, mining effluents have several contaminants that produce great damage to the environment, cyanide chief among them. Ferrites synthesized from transition metals have oxidative properties that can be used for cyanide oxidation due to their low solubility. In this study, cobalt and copper ferrites were synthesized via the precipitation method, using cobalt nitrate, copper nitrate, and iron nitrate as precursors in a molar ratio of Co or Cu:Fe = 1:2 and NaOH as the precipitating agent. The synthesized ferrites were impregnated in specific areas on active carbon. These composites were characterized using X-Ray Diffraction (XRD) and Scanning Electron Spectroscopy (SEM). The XRD results revealed a cubic spinel structure of ferrites with a single phase of cobalt ferrite and two phases (copper ferrite and copper oxides) for copper. The CoFe2O4 impregnated on active carbon reached a cyanide oxidation of 98% after 8 h of agitation; the composite could be recycled five times with an 18% decrease in the catalytic activity. In cobalt ferrites, a greater dissolution of iron than cobalt was obtained. In the case of copper ferrite, however, the copper dissolution was higher. These results confirm that ferrites and activated carbon composites are a novel alternative for cyanide treatment in mining effluents. Full article
(This article belongs to the Special Issue Metal Removal from Wastewater Using Biomass and Carbon-Based Materials)
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16 pages, 6512 KiB  
Article
Microstructural Evolution of Reaction Layer of 1.5 GPa Boron Steel Hot-Dipped in Al-7wt%Ni-6wt%Si Alloy
by Jeong-Yong Lee, Hoejun Heo, Namhyun Kang and Chung-Yun Kang
Metals 2018, 8(12), 1069; https://doi.org/10.3390/met8121069 - 15 Dec 2018
Cited by 1 | Viewed by 3031
Abstract
The constituents, distribution, and characteristics of the phases formed on the coating layer of boron steel hot-dipped in Al-7wt%Ni-6wt%Si were evaluated in detail. In particular, the microstructure and phase constitution of the reaction layer were characterized. Moreover, the microstructural evolution mechanism of the [...] Read more.
The constituents, distribution, and characteristics of the phases formed on the coating layer of boron steel hot-dipped in Al-7wt%Ni-6wt%Si were evaluated in detail. In particular, the microstructure and phase constitution of the reaction layer were characterized. Moreover, the microstructural evolution mechanism of the phase was presented with reference to the (Al-7wt%Ni-6wt%Si)-xFe from the pseudo-binary phase diagram. The solidification layer consisted mainly of Al, Al3Ni, and Si phases. Reaction layers were formed in the order of Al9FeNi(Τ), Fe4Al13(θ), and Fe2Al5(η) from the solidification layer side. In addition, the κ (Fe3AlC) layer was formed at the Fe2Al5(η)/steel interface. From pseudo-binary phase diagram analysis, it was found that Fe4Al13(θ) can form when the Fe concentration is over 2.63 wt% in the 690 °C Al-7wt%Ni-6wt%Si molten metal. When the concentration of Fe increased to 10.0–29.0 wt%, isothermal solidification occurred in the Fe4Al13(θ) and Al9FeNi(Τ) phases simultaneously. Moreover, given that the T phase does not dissolve Si, it was discharged, and the Si phase was formed around the Al9FeNi(T) phase. The Fe2Al5(η) phase was formed by a diffusion reaction between Fe4Al13(θ) and steel, not a dissolution reaction. Moreover, Al2Fe3Si3(τ1) was formed at the Fe4Al13(θ)-Fe2Al5(η) interface by discharging Si from Fe4Al13(θ) without Si solubility. Furthermore, the Fe3AlC(κ) layer was formed by carbon accumulation that discharged in the Fe2Al5(η) region transformed from steel to Fe2Al5(η). The twin regions in the Fe4Al13(θ) and Fe2Al5(η) grain were due to the strains caused by the lattice transformation in the constrained state, wherein the phases are present between the Al9FeNi(Τ) layer and steel. Full article
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11 pages, 6032 KiB  
Article
Distribution Ratio of Sulfur between CaO-SiO2-Al2O3-Na2O-TiO2 Slag and Carbon-Saturated Iron
by Kanghui Zhang, Yanling Zhang and Tuo Wu
Metals 2018, 8(12), 1068; https://doi.org/10.3390/met8121068 - 15 Dec 2018
Cited by 6 | Viewed by 4460
Abstract
To explore the feasibility of hot metal desulfurization using red mud, the sulfur distribution ratio (LS) between CaO-SiO2-Al2O3-Na2O-TiO2 slag and carbon-saturated iron is evaluated in this paper. First, the theoretical liquid [...] Read more.
To explore the feasibility of hot metal desulfurization using red mud, the sulfur distribution ratio (LS) between CaO-SiO2-Al2O3-Na2O-TiO2 slag and carbon-saturated iron is evaluated in this paper. First, the theoretical liquid areas of the CaO-SiO2-Al2O3 (-Na2O-TiO2) slag are discussed and the fluxing effects of Al2O3, Na2O, and TiO2 are confirmed. Then, LS is measured via slag-metal equilibrium experiments. The experimental results show that LS significantly increases with the increase of temperature, basicity, and Na2O content, whereas it decreases with the increase of Al2O3 and TiO2 content. Na2O in the slag will volatilize with high temperatures and reducing conditions. Furthermore, based on experimental data for the sulfur distribution ratio between CaO-SiO2-Al2O3-Na2O-TiO2 slag and the carbon-saturated iron, the following fitting formula is obtained: log L S = 45.584 Λ + 10568.406 − 17184.041 Λ T − 8.529 Full article
(This article belongs to the Special Issue Ironmaking and Steelmaking)
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9 pages, 5048 KiB  
Article
In Situ Formation of a Metastable β-Ti Alloy by Laser Powder Bed Fusion (L-PBF) of Vanadium and Iron Modified Ti-6Al-4V
by Florian Huber, Thomas Papke, Christian Scheitler, Lukas Hanrieder, Marion Merklein and Michael Schmidt
Metals 2018, 8(12), 1067; https://doi.org/10.3390/met8121067 - 14 Dec 2018
Cited by 25 | Viewed by 5723
Abstract
The aim of this work is to investigate the β-Ti-phase-stabilizing effect of vanadium and iron added to Ti-6Al-4V powder by means of heterogeneous powder mixtures and in situ alloy-formation during laser powder bed fusion (L-PBF). The resulting microstructure was analyzed by metallographic methods, [...] Read more.
The aim of this work is to investigate the β-Ti-phase-stabilizing effect of vanadium and iron added to Ti-6Al-4V powder by means of heterogeneous powder mixtures and in situ alloy-formation during laser powder bed fusion (L-PBF). The resulting microstructure was analyzed by metallographic methods, scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). The mechanical properties were characterized by compression tests, both prior to and after heat-treating. Energy dispersive X-ray spectroscopy showed a homogeneous element distribution, proving the feasibility of in situ alloying by LPBF. Due to the β-phase-stabilizing effect of V and Fe added to Ti-6Al-4V, instead of an α’-martensitic microstructure, an α/β-microstructure containing at least 63.8% β-phase develops. Depending on the post L-PBF heat-treatment, either an increased upsetting at failure (33.9%) compared to unmodified Ti-6Al-4V (28.8%), or an exceptional high compressive yield strength (1857 ± 35 MPa compared to 1100 MPa) were measured. The hardness of the in situ alloyed material ranges from 336 ± 7 HV0.5, in as-built condition, to 543 ± 13 HV0.5 after precipitation-hardening. Hence, the range of achievable mechanical properties in dependence of the post-L-PBF heat-treatment can be significantly expanded in comparison to unmodified Ti-6Al-4V, thus providing increased flexibility for additive manufacturing of titanium parts. Full article
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14 pages, 2824 KiB  
Article
A Novel Energy-Critical Multiaxial Fatigue Life Prediction for Low Cycle Fatigue under Mixed-Mode Loading
by Jie Zhou, Hong-Zhong Huang and He Li
Metals 2018, 8(12), 1066; https://doi.org/10.3390/met8121066 - 14 Dec 2018
Cited by 12 | Viewed by 3598
Abstract
Fatigue failure evolution is a process of damage accumulation under continued stresses and forces. The mechanical component is always subjected to various loadings and the lifespan is mainly governed by fatigue. The low cycle fatigue (LCF) is a key failure mode of many [...] Read more.
Fatigue failure evolution is a process of damage accumulation under continued stresses and forces. The mechanical component is always subjected to various loadings and the lifespan is mainly governed by fatigue. The low cycle fatigue (LCF) is a key failure mode of many components. In order to estimate the LCF life under multiaxial loadings in practical design, a modified model is proposed, based on the Fatemi-Socie (FS) and Smith-Watson-Topper (SWT) models, which considers the effects of shear and tensile behaviours. Then a novel judgment criterion is presented to distinguish the mixed-mode loadings and the procedures to employ the proposed model are also presented. Furthermore, two types of materials (TC4 and GH4169) and comparisons with the FS, Wang-Brown (WB) and redefined SWT (Re-SWT) models are employed to verify the accuracy and effectiveness of the proposed model, which has shown more reasonable predictions than the other models. Full article
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15 pages, 5111 KiB  
Article
Cavity Behavior of Fine-Grained 5A70 Aluminum Alloy during Superplastic Formation
by Sheng Li, Shunyao Jin and Zhongguo Huang
Metals 2018, 8(12), 1065; https://doi.org/10.3390/met8121065 - 14 Dec 2018
Cited by 10 | Viewed by 3255
Abstract
The study of the exact physical mechanism of cavity nucleation and growth is significant in terms of predicting the extent of internal damage following superplastic deformation. The 5A70 alloy was processed by cold rolling for 14 passes with a total reduction deformation of [...] Read more.
The study of the exact physical mechanism of cavity nucleation and growth is significant in terms of predicting the extent of internal damage following superplastic deformation. The 5A70 alloy was processed by cold rolling for 14 passes with a total reduction deformation of 90% (20–2 mm) and the heat treatment was inserted at a thickness of 10 and 5 mm at 340 °C for 30 min. The superplastic tensile tests were performed at 400, 450, 500, 550 °C and the initial strain rate was 1 × 10−3 s−1. Cavities were observed at the head of the particle and the interface of the grain boundaries. It is suggested that the cavity was nucleated during the sliding/climbing of the dislocations, due to the precipitate pinning effect and the impeding grain boundary during grain boundary sliding (GBS). In this study, the results demonstrated a clear transition from diffusion growth to superplastic diffusion growth and plastic-controlled growth at a cavity radius larger than 1.52 and 13.90 μm. The cavity nucleation, growth, interlinkage and coalescence under the applied stress during the superplastic deformation, as well as the crack formation and expansion during the deformation, ultimately led to the superplastic fracture. Full article
(This article belongs to the Special Issue Casting and Forming of Advanced Aluminum Alloys)
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11 pages, 2338 KiB  
Article
Formation and Evolution of Inclusions with Different Adding Order of Magnesium and Sulfur in Al-Killed Free-Cutting Steel
by Yi Min, Qingsong Zhang, Haisheng Xu, Jiujian Xu and Chengjun Liu
Metals 2018, 8(12), 1064; https://doi.org/10.3390/met8121064 - 14 Dec 2018
Cited by 6 | Viewed by 2871
Abstract
To reveal the effect of adding order of magnesium and sulfur on the evolution of inclusions in Al-killed free-cutting steel, both deoxidized experiments and thermodynamic calculations were carried out in this paper. The samples, which were extracted from the liquid steel at different [...] Read more.
To reveal the effect of adding order of magnesium and sulfur on the evolution of inclusions in Al-killed free-cutting steel, both deoxidized experiments and thermodynamic calculations were carried out in this paper. The samples, which were extracted from the liquid steel at different time after magnesium and sulfur addition, were analyzed by scanning electron microscopy and energy dispersive spectroscopy. The results showed that the adding order had a significant influence on the formation and evolution of inclusions. In the case of magnesium added before sulfur, MgO formed immediately after magnesium addition and then transformed to spinel accompanied by MeS (Mg0.9Mn0.1S) after sulfur addition. In the case of sulfur added prior to magnesium, MgO and MeS precipitated simultaneously after magnesium addition. During the equilibrium solidification, the transformation of MgO to spinel was calculated to take place before MnS precipitated from the saturated liquid steel. Full article
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9 pages, 3317 KiB  
Article
Phase Stability and Microstructure Evolution of Solution-Hardened 316L Powder Feedstock for Thermal Spraying
by Thomas Lindner, Martin Löbel and Thomas Lampke
Metals 2018, 8(12), 1063; https://doi.org/10.3390/met8121063 - 14 Dec 2018
Cited by 10 | Viewed by 3259
Abstract
A solution-hardening of AISI 316L stainless-steel powder was conducted. The expansion of the crystal lattice and a strong increase in the nanoindentation hardness confirm the successful diffusion of carbon and nitrogen in the interstices. A multiphase state of the powder feedstock with phase [...] Read more.
A solution-hardening of AISI 316L stainless-steel powder was conducted. The expansion of the crystal lattice and a strong increase in the nanoindentation hardness confirm the successful diffusion of carbon and nitrogen in the interstices. A multiphase state of the powder feedstock with phase fractions of the metastable S-phase (expanded austenite) mainly at the particle’s edge, and the initial austenitic phase within the core was found. Thermal spraying using high velocity oxy-fuel (HVOF) and atmospheric plasma spraying (APS) prove the sufficient thermal stability of the Sphase. Microstructural investigations of the HVOF coating reveal the ductility of the S-phase layer, while the higher heat load within the APS cause diffusion processes with the initial austenitic phase. The lattice expansion and the nanoindentation hardness decrease during thermal spraying. However, the absence of precipitates ensures the sufficient heat stability of the metastable S-phase. Even though further efforts are required for the thermochemical treatment of powder feedstock, the results confirm the feasibility of the novel powder treatment approach. Full article
(This article belongs to the Special Issue Thermal Spraying of Metallic Coatings)
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17 pages, 2390 KiB  
Article
Sustainable Hydrometallurgical Recovery of Valuable Elements from Spent Nickel–Metal Hydride HEV Batteries
by Kivanc Korkmaz, Mahmood Alemrajabi, Åke C. Rasmuson and Kerstin M. Forsberg
Metals 2018, 8(12), 1062; https://doi.org/10.3390/met8121062 - 14 Dec 2018
Cited by 23 | Viewed by 4692
Abstract
In the present study, the recovery of valuable metals from a Panasonic Prismatic Module 6.5 Ah NiMH 7.2 V plastic casing hybrid electric vehicle (HEV) battery has been investigated, processing the anode and cathode electrodes separately. The study focuses on the recovery of [...] Read more.
In the present study, the recovery of valuable metals from a Panasonic Prismatic Module 6.5 Ah NiMH 7.2 V plastic casing hybrid electric vehicle (HEV) battery has been investigated, processing the anode and cathode electrodes separately. The study focuses on the recovery of the most valuable compounds, i.e., nickel, cobalt and rare earth elements (REE). Most of the REE (La, Ce, Nd, Pr and Y) were found in the anode active material (33% by mass), whereas only a small amount of Y was found in the cathode material. The electrodes were leached in sulfuric acid and in hydrochloric acid, respectively, under different conditions. The results indicated that the dissolution kinetics of nickel could be slow as a result of slow dissolution kinetics of nickel oxide. At leaching in sulfuric acid, light rare earths were found to reprecipitate increasingly with increasing temperature and sulfuric acid concentration. Following the leaching, the separation of REE from the sulfuric acid leach liquor by precipitation as NaREE (SO4)2·H2O and from the hydrochloric acid leach solution as REE2(C2O4)3·xH2O were investigated. By adding sodium ions, the REE could be precipitated as NaREE (SO4)2·H2O with little loss of Co and Ni. By using a stoichiometric oxalic acid excess of 300%, the REE could be precipitated as oxalates while avoiding nickel and cobalt co-precipitation. By using nanofiltration it was possible to recover hydrochloric acid after leaching the anode material. Full article
(This article belongs to the Special Issue Extraction and Recycling of Refractory, Platinum Group Metals and Rare Earth Elements)
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10 pages, 3902 KiB  
Article
Diffusion Bonding of Ti2AlNb Alloy and High-Nb-Containing TiAl Alloy: Interfacial Microstructure and Mechanical Properties
by Hong Bian, Yuzhen Lei, Wei Fu, Shengpeng Hu, Xiaoguo Song and Jicai Feng
Metals 2018, 8(12), 1061; https://doi.org/10.3390/met8121061 - 14 Dec 2018
Cited by 17 | Viewed by 3793
Abstract
In this study, reliable Ti2AlNb/high-Nb-containing TiAl alloy (TAN) joints were achieved by diffusion bonding. The effects of bonding temperature and holding time on the interfacial microstructure and mechanical properties were fully investigated. The interfacial structure of joints bonded at various temperatures [...] Read more.
In this study, reliable Ti2AlNb/high-Nb-containing TiAl alloy (TAN) joints were achieved by diffusion bonding. The effects of bonding temperature and holding time on the interfacial microstructure and mechanical properties were fully investigated. The interfacial structure of joints bonded at various temperatures and holding times was characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The results show that the typical microstructure of the Ti2AlNb substrate/O phase/Al(Nb,Ti)2 + Ti3Al/Ti3Al/TAN substrate was obtained at 970 °C for 60 min under a pressure of 5 MPa. The formation of the O phase was earlier than the Al(Nb,Ti)2 phase when bonding temperature was relatively low. When bonding temperature was high enough, the Al(Nb,Ti)2 phase appeared earlier than the O phase. With the increase of bonding temperature and holding time, the Al(Nb,Ti)2 phase decomposed gradually. As the same time, continuous O phase layers became discontinuous and the Ti3Al phase coarsened. The maximum bonding strength of 66.1 MPa was achieved at 970 °C for 120 min. Full article
(This article belongs to the Special Issue Science, Characterization and Technology of Joining and Welding)
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12 pages, 1169 KiB  
Article
Multiaxial Fatigue Life Prediction on S355 Structural and Offshore Steel Using the SKS Critical Plane Model
by Alejandro S. Cruces, Pablo Lopez-Crespo, Belen Moreno and Fernando V. Antunes
Metals 2018, 8(12), 1060; https://doi.org/10.3390/met8121060 - 13 Dec 2018
Cited by 29 | Viewed by 3916
Abstract
This work analyses the prediction capabilities of a recently developed critical plane model, called the SKS method. The study uses multiaxial fatigue data for S355-J2G3 steel, with in-phase and 90° out-of-phase sinusoidal axial-torsional straining in both the low cycle fatigue and high cycle [...] Read more.
This work analyses the prediction capabilities of a recently developed critical plane model, called the SKS method. The study uses multiaxial fatigue data for S355-J2G3 steel, with in-phase and 90° out-of-phase sinusoidal axial-torsional straining in both the low cycle fatigue and high cycle fatigue ranges. The SKS damage parameter includes the effect of hardening, mean shear stress and the interaction between shear and normal stress on the critical plane. The collapse and the prediction capabilities of the SKS critical plane damage parameter are compared to well-established critical plane models, namely Wang-Brown, Fatemi-Socie, Liu I and Liu II models. The differences between models are discussed in detail from the basis of the methodology and the life results. The collapse capacity of the SKS damage parameter presents the best results. The SKS model produced the second-best results for the different types of multiaxial loads studied. Full article
(This article belongs to the Special Issue High-Strength Low-Alloy Steels)
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12 pages, 8375 KiB  
Article
Structure and Selected Properties of Arc Sprayed Coatings Containing In-Situ Fabricated Fe-Al Intermetallic Phases
by Tomasz Chmielewski, Piotr Siwek, Marcin Chmielewski, Anna Piątkowska, Agnieszka Grabias and Dariusz Golański
Metals 2018, 8(12), 1059; https://doi.org/10.3390/met8121059 - 13 Dec 2018
Cited by 27 | Viewed by 3305
Abstract
The paper presents the results of research on the production by means of arc spraying of composite coatings from the Fe-Al system with participation of in-situ intermetallic phases. The arc spraying process was carried out by simultaneously melting two different electrode wires, aluminum [...] Read more.
The paper presents the results of research on the production by means of arc spraying of composite coatings from the Fe-Al system with participation of in-situ intermetallic phases. The arc spraying process was carried out by simultaneously melting two different electrode wires, aluminum and steel. The aim of the research is to create protective coatings with a composite structure with a significant participation of FexAly as an intermetallic phases reinforcement. The synthesis of intermetallic phases takes place during the (in-situ) spraying process. Currently most coatings involving intermetallic phases are manufactured by different thermal spraying methods using coating materials in the form of prefabricated powders containing intermetallic phases. The obtained results showed the local occurrence of intermetallic phases from the Fe-Al system, and the dominant components of the structure have two phases, aluminum solid solutions in iron and iron in aluminum. The participation of intermetallic phases in the coating is relatively low, but its effect on the properties of the coating material is significant. Full article
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4 pages, 149 KiB  
Editorial
Plasma Electrolytic Oxidation of Metals and Alloys
by Tadeusz Hryniewicz
Metals 2018, 8(12), 1058; https://doi.org/10.3390/met8121058 - 12 Dec 2018
Cited by 17 | Viewed by 3281
Abstract
Porous oxide layers formed on metals and alloys via Plasma Electrolytic Oxidation (PEO) have been developed and used for decades in medicine and for technical purposes. [...] Full article
(This article belongs to the Special Issue Plasma Electrolytic Oxidation)
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