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Processing New High-Entropy Alloys via the In Situ Alloying of Commercial Powders Using Laser Powder Bed Fusion
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Magnetic Hardening of Heavily Helium-Ion-Irradiated Iron–Chromium Alloys
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Effect of Roller Burnishing and Slide Roller Burnishing on Fatigue Strength of AISI 304 Steel: Comparative Analysis
Journal Description
Metals
Metals
is an international, peer-reviewed, open access journal published monthly online by MDPI. The Portuguese Society of Materials (SPM), and the Spanish Materials Society (SOCIEMAT) are affiliated with Metals and their members receive a discount on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
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- Journal Rank: JCR - Q2 (Metallurgy and Metallurgical Engineering) / CiteScore - Q1 (Metals and Alloys)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 16.5 days after submission; acceptance to publication is undertaken in 2.6 days (median values for papers published in this journal in the first half of 2024).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Companion journals for Metals include: Compounds and Alloys.
Impact Factor:
2.6 (2023);
5-Year Impact Factor:
2.7 (2023)
Latest Articles
Research Progress in Corrosion Behavior and Anti-Corrosion Methods of Steel Rebar in Concrete
Metals 2024, 14(8), 862; https://doi.org/10.3390/met14080862 - 26 Jul 2024
Abstract
The corrosion of steel rebars is a prevalent factor leading to the diminished durability of reinforced concrete structures, posing a significant challenge to the safety of structural engineering. To tackle this issue, extensive research has been conducted, yielding a variety of theoretical insights
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The corrosion of steel rebars is a prevalent factor leading to the diminished durability of reinforced concrete structures, posing a significant challenge to the safety of structural engineering. To tackle this issue, extensive research has been conducted, yielding a variety of theoretical insights and remedial measures. This review paper offers an exhaustive analysis of the passivation processes and corrosion mechanisms affecting steel rebars in reinforced concrete. It identifies key factors such as chloride ion penetration and concrete carbonization that primarily influence rebar corrosion. Furthermore, this paper discusses a suite of strategies designed to enhance the longevity of reinforced concrete structures. These include improving the concrete protective layer’s quality and bolstering the rebars’ corrosion resistance. As corrosion testing is essential for evaluating steel rebars’ resistance, this paper also details natural and accelerated corrosion testing methods applicable to rebars in concrete environments. Additionally, this paper deeply presents an exploration of the use of X-ray computed tomography (X-CT) technology for analyzing the corrosion byproducts and the interface characteristics of steel bars. Recognizing the close relationship between steel bar corrosion research and microstructural properties, this paper highlights the pivotal role of X-CT in advancing this field of study. In conclusion, this paper synthesizes the current state of knowledge and provides a prospective outlook on future research directions on the corrosion of steel rebars within reinforced concrete structures.
Full article
(This article belongs to the Special Issue Advances in the Design and Behavior Analysis of High-Strength Steels)
Open AccessArticle
The Modification of Aluminum Oxide Inclusions in Bearing Steel under Different Cleanliness Conditions by Rare Earth Elements
by
Weining Wang, Wenzhi Xia, Yun Zhou, Aijun Deng, Guangda Bao, Zhiyou Liao and Haichuan Wang
Metals 2024, 14(8), 861; https://doi.org/10.3390/met14080861 - 26 Jul 2024
Abstract
The impact of rare earth treatment on the chemical morphology evolution of non-metallic inclusions in bearing steel under different initial cleanliness conditions was studied through simulation. Thermodynamic calculations indicate that at an oxygen content of 0.001%, the evolution route of inclusions with increasing
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The impact of rare earth treatment on the chemical morphology evolution of non-metallic inclusions in bearing steel under different initial cleanliness conditions was studied through simulation. Thermodynamic calculations indicate that at an oxygen content of 0.001%, the evolution route of inclusions with increasing Ce content was Al2O3 → CeAl11O18 + CeAlO3 → CeAlO3 + Ce2O2S → Ce2O2S → Ce2O2S + CeS. As the initial oxygen content decreases, the proportion of CeAlO3 decreases, leading to easier conversion of CeAlO3 to Ce2O2S. Vacuum induction furnace experiments demonstrated that with an oxygen content of 0.001%, an increase in Ce content results in a gradual rise in the proportion of inclusions in steel sized 1~2 μm. In contrast, the proportion of inclusions sized 2~5 μm decreases. Consequently, the overall content of inclusions in steel decreases, along with a reduction in both the number density and average size of inclusions. Introducing bearing steel melt with approximately 0.01% Ce rare earth to bearing steel with initial oxygen contents of 0.0005%, 0.001%, and 0.0015% showed an evolution of inclusions from Ce2O2S and CeS to Ce2O3, CeAlO3, etc. The average inclusion size significantly increased from 0.7 μm to 2.16 μm. Morphologically, the transition of inclusions from precipitated to polymerized forms occurred as the initial oxygen content rose. High-temperature laser confocal microscopy experiments demonstrated that inclusions in low cleanliness conditions tend to agglomerate more than those in high cleanliness conditions, contributing to the increase in average size.
Full article
(This article belongs to the Special Issue Green and Intelligent Steelmaking Technologies with Low Carbon Emissions)
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Open AccessArticle
Variation in Flow Characteristics of Molten Baths at Different Blowing Stages in the Converter
by
Ming Lv, Yijie Hao, Fuqing Hou, Shuangping Chen, Hongmin Guo and Zhaohui Zhang
Metals 2024, 14(8), 860; https://doi.org/10.3390/met14080860 - 26 Jul 2024
Abstract
The metallurgical tasks at different stages of converter blowing are different. The process operation and physical properties of molten baths are also different. It is very important to determine the flow characteristics of molten baths at different blowing stages for optimizing process operation.
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The metallurgical tasks at different stages of converter blowing are different. The process operation and physical properties of molten baths are also different. It is very important to determine the flow characteristics of molten baths at different blowing stages for optimizing process operation. In this paper, a three-dimensional, full-scale model of a 120 t top–bottom combined blowing converter is established. Based on the parameters of oxygen lance position, bath temperature, bottom blowing intensity, and bath physical properties at different blowing stages, the changes in bath flow field, turbulent kinetic energy, impact depth, impact area, and wall shear force with blowing process are studied. The results show that at the initial stage of blowing, the lance position is high, the impact depth of the molten bath is 0.23 m, the impact area is 5.06 m2, the dead zone area of the longitudinal section is 0.40 m2, and the high-speed zone area is 2.73 m2. As the blowing time increases, the lance position decreases, the impact depth of the molten bath increases, the impact area decreases, and the internal velocity of the molten bath increases. In the later stage of tuyere blowing, the lance level decreases to its lowest, the impact depth increases to 0.42 m, the impact area decreases to 2.83 m2, the dead zone area of longitudinal section decreases to 0.18 m2, and the high-speed area increases to 3.34 m2. The area with the highest wall shear stress is situated within the gas–slag–metal three-phase region, where the lining experiences the most significant erosion. The fluctuation in the slag–metal interface is small, and the wall shear force is 2.80 Pa at the initial stage of blowing. From the early to late stages of blowing, the lance position decreases, the fluctuation range of the slag–metal interface increases, and the erosion of the furnace lining increases. In the later stage of blowing, the maximum wall shear force is 3.81 Pa.
Full article
(This article belongs to the Section Extractive Metallurgy)
Open AccessArticle
Passivation Behavior of Chromium Alloyed High-Strength Rebar in Simulated Concrete Pore Solution
by
Hongxia Bao, Shangjun Gu, Jie Wang, Fulong Wei, Xiang Xie, Zhiying Li, Hui Yang, Zeyun Zeng and Changrong Li
Metals 2024, 14(8), 859; https://doi.org/10.3390/met14080859 - 26 Jul 2024
Abstract
In this study, SEM, AFM, TEM, XPS, and electrochemical tests are used to study the passivation behavior of chromium alloyed high-strength rebar in simulated concrete pore (SCP) solutions with different pH values. The results show that after passivation in SCP solution with different
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In this study, SEM, AFM, TEM, XPS, and electrochemical tests are used to study the passivation behavior of chromium alloyed high-strength rebar in simulated concrete pore (SCP) solutions with different pH values. The results show that after passivation in SCP solution with different pH values, the passivating film on the surface of the chromium alloyed rebar primarily consists of a layer of nanoscale oxide particles, which makes the passive film exhibit a p-n type semi-conductor, and the passive film presents a rhombohedral crystal structure. As the pH value of the SCP solution decreases, the nanoscale oxide particles on the surface of the rebar become denser, which leads to a reduction in the carrier density (Nq and Na) of the passive film and an increase in film resistance (R2) and charge transfer resistance (R3), thus increasing the corrosion resistance of the passive film. The passive film on the surface of the chromium alloyed high-strength rebar predominantly exhibits a three-layer structure, the outer passive film layer is composed of Fe oxides, the stable layer of the passive film is composed of Fe oxides and Cr oxides, and the growth layer of inner passive film is composed of Cr oxides. Compared with passivation 10 d in SCP solutions with pH 13.5 and pH 12.5, the passive film on the surface of the rebar has good stability at pH 10.5, which indicates that the addition of Cr is beneficial to promote the corrosion resistance of the rebar.
Full article
Open AccessArticle
A Study on Powder Metallurgy Process for x Electric Vehicle Stator Core
by
Jaemin Kim and Seonbong Lee
Metals 2024, 14(8), 858; https://doi.org/10.3390/met14080858 - 26 Jul 2024
Abstract
The powder metallurgy process of manufacturing the motor core and inductor core using SMC greatly changes formability depending on the process variables. Therefore, this study explored the optimal process conditions of the powder metallurgy of the SMC stator core using Fe-6.5 wt.%Si by
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The powder metallurgy process of manufacturing the motor core and inductor core using SMC greatly changes formability depending on the process variables. Therefore, this study explored the optimal process conditions of the powder metallurgy of the SMC stator core using Fe-6.5 wt.%Si by applying the Taguchi method, and selected deviations between the maximum and minimum relative densities as characteristic values; selected the formation pressure, molding temperature, and heating time as control factors; and derived the process conditions with the maximum SNR. As a result, the molding pressure was 120 MPa, the molding temperature was 500 °C, and the heating time was 120 s, and the material properties of the electrical properties’ core loss, saturation flux density, and bulk conductivity were measured and analyzed. After that, a prototype was produced, the analysis was verified, the mechanical properties were verified by performing density and SEM analysis at 15, 9, and 3 mm points based on the press vertical direction, and a motor was manufactured to verify the electrical properties.
Full article
(This article belongs to the Special Issue Soft Magnetic Composites: Manufacture, Properties and Applications)
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Open AccessArticle
Reduction in Porosity in GMAW-P Welds of CP780 Galvanized Steel with ER70S-3 Electrode Using the Taguchi Methodology
by
Maleni García-Gómez, Francisco Fernando Curiel-López, José Jaime Taha-Tijerina, Víctor Hugo López-Morelos, Julio César Verduzco-Juárez and Carlos Adrián García-Ochoa
Metals 2024, 14(8), 857; https://doi.org/10.3390/met14080857 - 26 Jul 2024
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In this study, the theoretical welding parameters influencing porosity formation were examined with the aim of reducing or minimizing porosity levels. An experimental design was implemented using the Taguchi methodology for data analysis, resulting in an L9 orthogonal array matrix of experiments. The
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In this study, the theoretical welding parameters influencing porosity formation were examined with the aim of reducing or minimizing porosity levels. An experimental design was implemented using the Taguchi methodology for data analysis, resulting in an L9 orthogonal array matrix of experiments. The welding variables considered in the orthogonal array were peak current, peak time, and frequency. Nine lap welds were performed on CP780 steel using the gas metal arc welding process with pulsed arc (GMAW-P), employing an ER70S-3 electrode as filler metal. The percentage of porosity was determined as a response variable, and the actual heat input was treated as a covariable, thereby identifying the welding parameters with the predicted values. Three repetitions were conducted with the optimal welding parameters to validate the Taguchi prediction. The quality of the welds was assessed through radiographic inspection, and metallographic preparation was performed, revealing the microstructure with 5% Nital for 12 s. The samples were analyzed using an optical microscope, and images were obtained with the collage technique. The results showed that the welding parameters predicted by the Taguchi statistics were favorable for all three predicted welded joints. The maximum percentage of porosity obtained was 19%, which was reduced to 1% using the Taguchi methodology, demonstrating the effectiveness of this statistical tool for process optimization. It was observed that for heat input values of 230 to 250 J/mm, the presence of porosities is dramatically reduced, finding a very small window that allows the gases generated by the burning of zinc to be expelled to the surface.
Full article
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Open AccessArticle
Research on Molten Iron Quality Prediction Based on Machine Learning
by
Ran Liu, Zi-Yang Gao, Hong-Yang Li, Xiao-Jie Liu and Qing Lv
Metals 2024, 14(8), 856; https://doi.org/10.3390/met14080856 - 26 Jul 2024
Abstract
The quality of molten iron not only has a significant impact on the strength, toughness, smelting cost and service life of cast iron but also directly affects the satisfaction of users. The establishment of timely and accurate blast furnace molten iron quality prediction
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The quality of molten iron not only has a significant impact on the strength, toughness, smelting cost and service life of cast iron but also directly affects the satisfaction of users. The establishment of timely and accurate blast furnace molten iron quality prediction models is of great significance for the improvement of the production efficiency of blast furnace. In this paper, Si, S and P content in molten iron is taken as the important index to measure the quality of molten iron, and the 989 sets of production data from a No.1 blast furnace from August to October 2020 are selected as the experimental data source, predicting the quality of molten iron by the I-GWO-CNN-BiLSTM model. First of all, on the basis of the traditional data processing method, the missing data values are classified into correlation data, temporal data, periodic data and manual input data, and random forest, the Lagrangian interpolation method, the KNN algorithm and the SVD algorithm are used to complete them, so as to obtain a more practical data set. Secondly, CNN and BiLSTM models are integrated and I-GWO optimized hyperparameters are used to form the I-GWO-CNN-BiLSTM model, which is used to predict Si, S and P content in molten iron. Then, it is concluded that using the I-GWO-CNN-BiLSTM model to predict the molten iron quality can obtain high prediction accuracy, which can provide data support for the regulation of blast furnace parameters. Finally, the MCMC algorithm is used to analyze the influence of the input variables on the Si, S and P content in molten iron, which helps the steel staff control the quality of molten iron in a timely manner, which is conducive to the smooth running of blast furnace production.
Full article
(This article belongs to the Special Issue Advanced Metal Smelting Technology and Prospects)
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Open AccessArticle
The Optimization of the Synthesis of Antibacterial Coatings on Ti6Al4V Coupons Obtained by Electron Beam Melting
by
Javier Molina, Ana Valero-Gómez, Patricia Bernabé-Quispe, María Ángeles Tormo-Mas and Francisco Bosch
Metals 2024, 14(8), 855; https://doi.org/10.3390/met14080855 - 25 Jul 2024
Abstract
Prosthetic joint infection represents a problem that worsens the patient’s quality of life and produces an economic impact on health systems. We report the anodization of Ti6Al4V coupons obtained by electron beam melting to produce a nanostructured surface. Anodization at 10 V produced
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Prosthetic joint infection represents a problem that worsens the patient’s quality of life and produces an economic impact on health systems. We report the anodization of Ti6Al4V coupons obtained by electron beam melting to produce a nanostructured surface. Anodization at 10 V produced TiO2 nanopores with a diameter in the range of 15–20 nm. Thereafter, Ag nanoparticles (AgNPs) were deposited in three different ways to provide antibacterial functionality to the coatings: electrochemically, thermally, and chemically. The electrochemical method did not provide good coverage of AgNPs. At 0.1 V of synthesis potential, cubic, octahedral, and truncated octahedral Ag crystals were obtained. The thermal method provided a good distribution of AgNPs but it damaged the TiO2 nanostructure. The chemical method showed the best distribution of AgNPs over the anodized surface and preserved the anodized nanostructure. For this reason, the chemical method was selected to perform further studies. Ag+ release was monitored in simulated body fluid at 37 °C, reaching 1.86 mg Ag+/L after 42 days. The antibacterial coating showed excellent antibacterial activity and inhibited biofilm formation for Staphylococcus epidermidis RP62A and Staphylococcus aureus V329 strains (lethality > 99.9% for both bacteria and assays).
Full article
(This article belongs to the Special Issue Additive Manufacturing of Light Metal Alloys)
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Open AccessArticle
Microstructural Evolution and Subsequent Mechanical Properties of Ti65 Titanium Alloy during Long-Term Thermal Exposure
by
Juan Li, Wentao Jiang, Chunlin Xia, Yuting Deng, Yue Gao and Changyi Yang
Metals 2024, 14(8), 854; https://doi.org/10.3390/met14080854 - 25 Jul 2024
Abstract
The microstructural stability and property evolution of high-temperature titanium alloys under long-term high-temperature conditions has been a critical scientific issue in the field of advanced titanium alloys. In this work, we systematically investigated the precipitation behavior of silicides and ordered α2 phase,
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The microstructural stability and property evolution of high-temperature titanium alloys under long-term high-temperature conditions has been a critical scientific issue in the field of advanced titanium alloys. In this work, we systematically investigated the precipitation behavior of silicides and ordered α2 phase, which are closely related to the microstructural stability of Ti65 high-temperature alloy, during thermal exposure at 650 °C for different periods of time. Furthermore, the effects of thermal exposure on mechanical properties were evaluated using room temperature and high temperature tensile tests, and subsequently, the correlation between the microstructural thermal stability and the mechanical characteristics was discussed. The results reveal that (Ti, Zr)6Si3 silicides initially precipitate within the residual β film and then start to precipitate in the α platelet. A large number of fine spherical α2 precipitates were formed inside the α platelet after a short thermal exposure. The number density of ordered α2 decreased significantly after 1000 h due to Ostwald ripening. The precipitation of silicides and ordered α2 phases during thermal exposure improves the tensile strength but deteriorates the ductility, and the room-temperature ductility is slightly restored due to α2 ripening after long-time thermal exposure. Ti65 high-temperature titanium alloy consistently maintains favorable room-temperature tensile properties throughout long-term thermal exposure.
Full article
(This article belongs to the Special Issue Design, Phase Transformation and Mechanical Properties of Titanium Alloy)
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Open AccessArticle
The Effects of Three Antibacterial Nanoparticle Coatings on the Surface Characteristics of Stainless Steel
by
Ahmed Muhsin Yousif Al-Mayali, Ammar S. Khadhum and Thair L. Alzubaydi
Metals 2024, 14(8), 853; https://doi.org/10.3390/met14080853 - 25 Jul 2024
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The aim of this study is to investigate the antibacterial capabilities of different coating durations of three nanoparticle (NP) coatings: molybdenum (Mo), tantalum (Ta), and zinc oxide (ZnO), and their effects on the surface characteristics of 316L stainless steel (SS). The coated substrates
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The aim of this study is to investigate the antibacterial capabilities of different coating durations of three nanoparticle (NP) coatings: molybdenum (Mo), tantalum (Ta), and zinc oxide (ZnO), and their effects on the surface characteristics of 316L stainless steel (SS). The coated substrates underwent characterization utilizing field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffractometer (XRD) techniques. The antibacterial efficacy of NPs was evaluated using the agar diffusion method. The FE-SEM and EDX images confirmed the presence of nano-sized particles of Mo, Ta, and ZnO on the surface of the substrates with perfectly symmetrical spheres and a uniform distribution of the NPs. All groups demonstrated antibacterial activity, and the ability to inhibit the growth of Streptococcus mutans and Lactobacillus acidophilus bacteria. The ZnO group had the most potent antibacterial effect, followed by the Mo group, while the Ta group had the least effect. A direct-current (DC) plasma sputtering system was used to produce nano-coatings of high purity that were homogeneous, crack-free and showed no sign of delamination. Bacterial strains exposed to Mo, Ta, and ZnO coated surfaces exhibited a significant loss of viability in a time-dependent manner. The optimum sputtering time to ensure the best antibacterial properties and preserve the resources was 1 hour (h) for Mo, 3 h for Ta and 6 h for ZnO.
Full article
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Open AccessArticle
Finite Element Modeling and Experimental Verification of a New Aluminum Al-2%Cu-2%Mn Alloy Hot Cladding by Flat Rolling
by
Alexander Koshmin, Alexander Zinoviev, Stanislav Cherkasov, Abdullah Mahmoud Alhaj Ali, Kirill Tsydenov and Alexander Churyumov
Metals 2024, 14(8), 852; https://doi.org/10.3390/met14080852 - 25 Jul 2024
Abstract
The roll bonding of an experimental Al-2%Cu-2%Mn alloy with technically pure 1050A aluminum at true deformations of 0.26, 0.33 and 0.40 has been simulated using the QForm 10.3.0 FEM software. The flow stress of the Al-2%Cu-2%Mn alloy has been measured in temperature and
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The roll bonding of an experimental Al-2%Cu-2%Mn alloy with technically pure 1050A aluminum at true deformations of 0.26, 0.33 and 0.40 has been simulated using the QForm 10.3.0 FEM software. The flow stress of the Al-2%Cu-2%Mn alloy has been measured in temperature and strain rate ranges of 350–450 °C and 0.1–20 s−1, respectively. The simulation results suggest that the equivalent strain in the cladding layer is more intense than that in the base layer, reaching 1.0, 1.4 and 2.0 at strains of 0.26, 0.33 and 0.40, respectively. The latter fact favors a decrease in the difference between the flow stresses of the rolled sheet layer contact surfaces by an average of 25% at the highest strain. The experimental roll bonding has achieved good layer adhesion for all the test samples. The average peeling strength of the samples produced at strains of 0.26 and 0.33 proves to be 12.6 and 18.4 N/mm, respectively, and at a strain of 0.40, it has exceeded the flow stress of the 1050A alloy cladding layer. The change in the rolling force for different rolling routes has demonstrated the best fit with the experimental data.
Full article
(This article belongs to the Section Metal Casting, Forming and Heat Treatment)
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Open AccessArticle
A Chip Formation Study of the Micro-Cutting of Commercially Pure Titanium
by
João Octávio Marçal Assis, Carlos Henrique Lauro, Robson Bruno Dutra Pereira, Lincoln Cardoso Brandão, Étory Madrilles Arruda and João Paulo Davim
Metals 2024, 14(8), 851; https://doi.org/10.3390/met14080851 - 25 Jul 2024
Abstract
In recent years, micro-cutting has been employed to obtain components that are more detailed and/or have great surface quality, regardless of dimensions, like dental implants. In the manufacturing of medical/dental components, titanium and its alloys are biomaterials of great notability. Like in conventional
[...] Read more.
In recent years, micro-cutting has been employed to obtain components that are more detailed and/or have great surface quality, regardless of dimensions, like dental implants. In the manufacturing of medical/dental components, titanium and its alloys are biomaterials of great notability. Like in conventional machining, sustainability is a delicate issue because it does not only depend on environmental aspects. One simple solution would be to perform dry machining. However, in the machining of difficult-to-cut materials, like titanium and its alloys, the use of cutting fluids is generally recommended to avoid the high temperature causing damage to the tool and/or machined surface. Concerned with the quality surface that is required for dental components, this work investigates the use of cutting fluid in the micro-cutting of commercially pure titanium. Orthogonal micro-cutting experiments were carried out under dry and wet conditions, using cutting fluid at room and cooled temperatures. To evaluate the lubri-cooling performance, cutting efforts, the friction coefficient, specific cutting energy, and chip formation analysis were compared. The outcomes indicated that, under the test conditions, the use of dry cutting and high feed levels had a positive effect on micro-cutting performance.
Full article
(This article belongs to the Section Metal Casting, Forming and Heat Treatment)
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Open AccessArticle
Effects of Different Austenitising Conditions on the Strength–Ductility Balance in a High-Strength Low-Alloy Steel
by
Liang Luo, Duyu Dong, Zheng Jiang, Tao Chen and Yimin Li
Metals 2024, 14(8), 850; https://doi.org/10.3390/met14080850 - 25 Jul 2024
Abstract
With the addition of microalloy elements to a high-strength low-alloy (HSLA) steel, various fine particles of carbides and nitrides are formed, which increase the matrix strength. These precipitates play a crucial role in precipitation strengthening. However, the role of precipitates in microstructural refinement
[...] Read more.
With the addition of microalloy elements to a high-strength low-alloy (HSLA) steel, various fine particles of carbides and nitrides are formed, which increase the matrix strength. These precipitates play a crucial role in precipitation strengthening. However, the role of precipitates in microstructural refinement is frequently overlooked. In this study, a series of hot-rolled HSLA steel samples were reheated to different temperatures above the austenite transformation point for a specified period to refine austenite grains via precipitation, then cooled to a dual-phase (austenitic/ferritic) region, and finally air-cooled to room temperature. The influences of different austenitising conditions on the microstructure and mechanical properties of the HSLA steel were examined. When a hot-rolled sample was reheated to 15 °C above the austenitic transition temperature for 20 min and then cooled to 25 °C below the austenitic transition temperature for 25 min, the most low-angle boundaries were formed, and the smallest effective grain size was achieved. Meanwhile, compared with the hot-rolled sample, the tensile and yield strengths of the reheated sample increased by 12.3% and 3.4%, respectively, while the elongation increased by 162.5%, exhibiting a good strength–ductility balance. By adopting an appropriate austenitising process, precipitates can refine the crystalline grains during austenitisation, thereby enhancing the comprehensive mechanical properties of the steel. Meanwhile, excessively high austenitising temperatures lead to the coarsening of the steel microstructure, decreasing the microstructural refinement efficiency via precipitation and consequently degrading the comprehensive mechanical properties of the steel. The findings provide valuable insights into the preparation process design of such steels or other steels with similar microstructures.
Full article
(This article belongs to the Special Issue Advances in Phase Transformation Behavior of Steels)
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Open AccessArticle
The Action Mechanism of Rolling Texture on the Anisotropic Behavior of a Pure Titanium Plate
by
Sanzhong Wang, Wei Li, Ziteng Huang, Songsong Li, Genmao Zhang and Hui Yu
Metals 2024, 14(8), 849; https://doi.org/10.3390/met14080849 - 24 Jul 2024
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This work combined theoretical calculation with experimental characterization to methodically study the anisotropy mechanism and evolution of the plastic behavior of pure titanium. Initially, a constant-strain uniaxial tensile test was used to measure the anisotropy of the yield behavior along the rolling direction
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This work combined theoretical calculation with experimental characterization to methodically study the anisotropy mechanism and evolution of the plastic behavior of pure titanium. Initially, a constant-strain uniaxial tensile test was used to measure the anisotropy of the yield behavior along the rolling direction (RD) and transverse direction (TD). Subsequently, the information of crystal orientation both before and after deformation was statistically characterized using electron backscatter diffraction (EBSD). Ultimately, the main deformation mechanism was determined by combining Schmid law with an analysis of the variation of SF values of each deformation mode with the angular relationship between the loading axis and the grain’s c-axis. The findings demonstrate that, for each slip system, the variation trend and value of the SF are influenced by the angle formed by the loading axis and the grain’s c- and a-axes. The primary result of dislocation slip activation is the change of the tilt angle of the grain c-axis from ND to TD, but this has little effect on the tilt angle of the grain c-axis from ND to RD. Prismatic <a> slip dominates the tensile deformation along the RD. Pyramidal <a> slip and pyramidal <c+a> slip will be activated during the subsequent hardening, whereas basal <a> slip is difficult to activate. The prismatic <a> slip in the soft-oriented grain will be preferentially activated during the tensile deformation along the TD, and the prismatic <a> slip and pyramidal <a> slip will become the dominant deformation modes during the subsequent hardening. Some soft-oriented grains could activate basal <a> slip and pyramidal <c+a> slip, but dislocation slip is restricted and coordinated by {10-12}ET.
Full article
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Open AccessArticle
Stabilization Effect of Interfacial Solute Segregation on θ′ Precipitates in Al-Cu Alloys
by
Shangshang Liang, Shengping Wen, Baosheng Liu, Yong Hu, Wu Wei, Xiaolan Wu, Hui Huang, Kunyuan Gao, Xiangyuan Xiong and Zuoren Nie
Metals 2024, 14(8), 848; https://doi.org/10.3390/met14080848 - 24 Jul 2024
Abstract
The effects of Sc, Mg and Si elements in an Al-Cu alloy have been studied by means of hardness tests and transmission electron microscopy analysis. The experimental results show that additions of Sc, Mg and Si can improve the heat resistance of the
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The effects of Sc, Mg and Si elements in an Al-Cu alloy have been studied by means of hardness tests and transmission electron microscopy analysis. The experimental results show that additions of Sc, Mg and Si can improve the heat resistance of the Al-Cu alloy. The Sc/Mg/Si segregation-sandwiched structure is the most stable, when compared with Sc segregation or Si/Sc co-segregation at the interface of θ′/Al. The additions of Si and Mg promote the aging–hardening response of the Al-Cu alloy. Mg is a micro-alloying element with great potential in stabilizing the size of θ′ phases, which further promotes the number density greatly. Consequently, the Al-Cu alloy achieves a high strength, matched with excellent thermal stability, due to the microalloying of Sc/Mg/Si solutes.
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(This article belongs to the Topic Microstructure and Properties in Metals and Alloys, 3rd Volume)
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Open AccessArticle
Ultrasonic-Assisted Granular Medium Forming of Aluminum Alloy 6063-T5: Simulations and Experiments
by
Han Hu, Feng Yu, Song Zhang, Jing Yin, Haiyan Zhang, Jiaru Zhang, Xiaonan Zhang, Miaoyan Cao and Shahzad Murtaza
Metals 2024, 14(8), 847; https://doi.org/10.3390/met14080847 - 24 Jul 2024
Abstract
To address the challenges posed by the complex shapes of hollow parts, this study examined the ultrasonic-assisted granular medium hydroforming (UGMF) process for tubular components. The dynamics of the deformation behavior and deformation control during 6063-T5 aluminum alloy tube free forming by UGMF
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To address the challenges posed by the complex shapes of hollow parts, this study examined the ultrasonic-assisted granular medium hydroforming (UGMF) process for tubular components. The dynamics of the deformation behavior and deformation control during 6063-T5 aluminum alloy tube free forming by UGMF were studied via simulations and experiments. Based on the ABAQUS software platform, a coupled method based on finite element (FE) simulation analysis and discrete element (DE) analysis for the UGMF free forming process was used. The results showed that ultrasonic vibration (UV) could reduce the forming force required for expansion and promote the flow of material at the end to the forming area as well as inhibit the decrease in the wall thickness. The accuracy of the FE-DE coupled simulation model and a parabolic geometric model was verified by testing. The results found that UV enhances material flow, decreases the forming force needed, and minimizes damage to the granular surface.
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(This article belongs to the Special Issue Advanced Forming Process of Light Alloy)
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Open AccessArticle
Effect of Annealing after Casting and Cold Rolling on Microstructure and Electrochemical Behavior of High-Entropy Alloy, Cantor
by
Jinsurang Lim, Byung-Hyun Shin, Doo-In Kim, Jong-Seong Bae, Jung-Woo Ok, Seongjun Kim, Jinyong Park, Je In Lee and Jang-Hee Yoon
Metals 2024, 14(8), 846; https://doi.org/10.3390/met14080846 - 24 Jul 2024
Abstract
High-entropy alloys (HEAs), a relatively new class of materials, have attracted significant attention in materials science owing to their unique properties and potential applications. High entropy stabilizes the phase of a solid solution over a wide range of chemical compositions, yielding unique properties
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High-entropy alloys (HEAs), a relatively new class of materials, have attracted significant attention in materials science owing to their unique properties and potential applications. High entropy stabilizes the phase of a solid solution over a wide range of chemical compositions, yielding unique properties superior to those of conventional alloys. Therefore, this study analyzed the microstructure and electrochemical behavior of HEAs (Cantor) to evaluate their corrosion resistance, according to their manufacturing process (casting, cold rolling, and annealing). The microstructural morphologies and sizes were analyzed using electron backscatter diffraction. The electrochemical behavior was examined using open circuit potential measurements, electrochemical impedance spectroscopy, potentiodynamic polarization tests, and critical pitting temperature measurements using a potentiostat. The casting process formed a nonuniform microstructure (average grain size = 19 μm). The cold rolling process caused the formation of fine grains (size = 4 μm). A uniform microstructure (grain size > 151 μm) was formed after heat treatment. The corrosion resistance of the HEAs was determined from the passivation layer formed by Cr oxidation. These microstructural differences resulted in variations in the electrochemical behavior. Microstructural and electrochemical analyses are crucial because HEAs have diverse potential applications. Therefore, this study contributes to future improvements in HEA manufacturing processes.
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(This article belongs to the Special Issue Casting Alloy Design and Characterization—2nd Edition)
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Open AccessArticle
Finite Element Simulation of Multi-Pass Rolling of a Pure Aluminum Target under Different Rolling Routes and Methods
by
Chaoxin Qiu, Rui Xu, Xin Xu and Shengcan Ma
Metals 2024, 14(8), 845; https://doi.org/10.3390/met14080845 - 24 Jul 2024
Abstract
By coordinating the rolling direction and mode, a multi-rolling plastic deformation process for an aluminum (Al) sputter target is proposed to achieve multiple excellent properties, including a uniform and fine grain structure and low defect risk, which are significant in producing high-quality sputtered
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By coordinating the rolling direction and mode, a multi-rolling plastic deformation process for an aluminum (Al) sputter target is proposed to achieve multiple excellent properties, including a uniform and fine grain structure and low defect risk, which are significant in producing high-quality sputtered films. In this work, therefore, DEFORM 3D 10.2 software is adopted to establish three strategies, clock-synchronous rolling, cross-synchronous rolling, and clock–snake rolling. The effect of different rolling routes and modes on the metal flow velocity (MFV), effective strain distribution (ESD), grain size distribution (GSD), damage, and rolling force (RF) are comparatively investigated. The simulation results show that clock–snake rolling can increase the MFV and effective strain by producing a deeper deformation than the others. It provides sufficient energy for dynamic recrystallization to promote grain refinement. In combination with the microstructure homogeneity promoted by the clock rolling route, the GSD from 6.5 to 44.3 μm accounts for about 80.5% of all the grains because of the fact that a randomly oriented grain region is full of high-angle grain boundaries. Compared with the synchronous rolling mode, the decrement in RF maximum reaches up to 51% during the asynchronous rolling process because component energy is consumed to form cross-sheering stress. It remarkably reduces the risk of defects, with a damage value of less than 73%, and simultaneously improves energy efficiency owing to smaller and uniform grains caused by less RF. The results obtained in this work are of great significance as they can guide practical production in the metal target industry.
Full article
(This article belongs to the Special Issue Numerical Simulation and Experimental Research of Metal Rolling)
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Open AccessArticle
Novel Aging Warm-Forming Process of Al-Zn-Mg Aluminum Alloy Sheets and Influence of Precipitate Characteristics on Warm Formability
by
Wan-Ling Chen and Rong-Shean Lee
Metals 2024, 14(8), 844; https://doi.org/10.3390/met14080844 - 24 Jul 2024
Abstract
Concurrently improving the formability and post-formed strength of Al-Zn-Mg alloy sheets is crucial for producing high-strength parts with complex shapes. A novel process of aging warm-forming (AWF) to form solution heat-treated and water-quenched aluminum alloy sheets is proposed in this paper. The as-quenched
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Concurrently improving the formability and post-formed strength of Al-Zn-Mg alloy sheets is crucial for producing high-strength parts with complex shapes. A novel process of aging warm-forming (AWF) to form solution heat-treated and water-quenched aluminum alloy sheets is proposed in this paper. The as-quenched AA 7075 sheet was first pre-aged and then formed at the desired temperature. The automotive paint–bake process was then utilized as the second aging step to achieve the target strength of the formed part. Additionally, the post-formed strength and warm formability of specimens under the AWF process conditions, as well as the warm-forming of various heat-treated Al-Zn-Mg alloy sheets proposed in previous studies, were compared through tensile and limit dome height tests. Precipitate characteristics of specimens subjected to different warm-forming process conditions were examined to understand their impact on warm formability. The warm formability of Al-Zn-Mg alloy sheets was significantly enhanced, and the post-formed strength achieved was more than 90% of the strength of as-received AA 7075-T6 sheets under the AWF process condition. The results demonstrated the feasibility of this novel AWF process to manufacture Al-Zn-Mg alloy stamped parts for improved spring-back, formability, and good overall post-formed strength. The results also indicate that microstructural characteristics in Al-Zn-Mg alloy sheets under different warm-forming process conditions have a noticeable influence on warm formability and final mechanical properties.
Full article
(This article belongs to the Special Issue Novel Insights into Hot Sheet Metal Forming of High-Performance Materials)
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Open AccessArticle
Metallic Degenerately Doped Free-Electron-Confined Plasmonic Nanocrystal and Infrared Extinction Response
by
Do-Yoon Park and Shin-Hum Cho
Metals 2024, 14(8), 843; https://doi.org/10.3390/met14080843 - 24 Jul 2024
Abstract
In this paper, synthetically scaled-up degenerately n-type doped indium tin oxide (Sn:In2O3) nanocrystals are described as highly transparent conductive materials possessing both optoelectronic and crystalline properties. With tin dopants serving as n-type semiconductor materials, they can generate free-electron carriers.
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In this paper, synthetically scaled-up degenerately n-type doped indium tin oxide (Sn:In2O3) nanocrystals are described as highly transparent conductive materials possessing both optoelectronic and crystalline properties. With tin dopants serving as n-type semiconductor materials, they can generate free-electron carriers. These free electrons, vibrating in resonance with infrared radiation, induce strong localized surface plasmon resonance (LSPR), resulting in efficient infrared absorption. To commercialize products featuring Sn:In2O3 with localized surface plasmon resonance, a scaled-up synthetic process is essential. To reduce the cost of raw materials during synthesis, we aim to proceed with synthesis in a large reactor using industrial raw materials. Sn:In2O3 can be formulated into ink dispersed in solvents. Infrared-absorbing ink formulations can capitalize on their infrared absorption properties to render opaque in the infrared spectrum while remaining transparent in the visible light spectrum. The ink can serve as a security ink material visible only through infrared cameras and as a paint absorbing infrared light. We verified the transparency and infrared absorption properties of the ink produced in this study, demonstrating consistent characteristics in scaled-up synthesis. Due to potential applications requiring infrared absorption properties, it holds significant promise as a robust platform material in various fields.
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(This article belongs to the Special Issue Self-Organization in Plasticity of Metals and Alloys)
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