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.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, CAPlus / SciFinder, and other databases.
- Journal Rank: JCR - Q2 (Metallurgy & Metallurgical Engineering) / CiteScore - Q1 (Metals and Alloys)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 15 days after submission; acceptance to publication is undertaken in 2.7 days (median values for papers published in this journal in the second half of 2023).
- 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:
2.9 (2022);
5-Year Impact Factor:
2.9 (2022)
Latest Articles
Some Recent Advances in Germanium Recovery from Various Resources
Metals 2024, 14(5), 559; https://doi.org/10.3390/met14050559 (registering DOI) - 9 May 2024
Abstract
Though nowadays germanium does not reach the range of popularity of other metals, i.e., rare earth elements, its utility in target industries makes it a strategic metal. Though germanium can be found in a series of raw materials, the principal source for its
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Though nowadays germanium does not reach the range of popularity of other metals, i.e., rare earth elements, its utility in target industries makes it a strategic metal. Though germanium can be found in a series of raw materials, the principal source for its recovery is from secondary wastes of the zinc industry; also, the recyclability of germanium-bearing waste materials is becoming of interest. In this recovery and due to the size of the target materials, because the diffusion and reaction are to be considered, hydrometallurgy performs a key role in achieving this goal. The present work reviews the most recent applications (2023 and 2024 years) of hydrometallurgical operations on the recovery of germanium from different solid and liquid sources.
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(This article belongs to the Special Issue Advances in Sustainable Hydrometallurgy)
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High-Throughput Multi-Principal Element Alloy Exploration Using a Novel Composition Gradient Sintering Technique
by
Brady L. Bresnahan and David L. Poerschke
Metals 2024, 14(5), 558; https://doi.org/10.3390/met14050558 - 9 May 2024
Abstract
This work demonstrates the capabilities and advantages of a novel sintering technique to fabricate bulk composition gradient materials. Pressure distribution calculations were used to compare several tooling geometries for use with current-activated, pressure-assisted densification or spark plasma sintering to densify a gradient along
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This work demonstrates the capabilities and advantages of a novel sintering technique to fabricate bulk composition gradient materials. Pressure distribution calculations were used to compare several tooling geometries for use with current-activated, pressure-assisted densification or spark plasma sintering to densify a gradient along the long dimension of the specimen. The selected rectangular tooling design retains a low aspect ratio to ensure a uniform pressure distribution during consolidation by using a side loading configuration to form the gradient along the longest dimension. Composition gradients of NixCu1−x, MoxNb1−x, and MoNbTaWHfx (x from 0 to 1) were fabricated with the tooling. The microstructure, composition, and crystal structure were characterized along the gradient in the as-sintered condition and after annealing to partially homogenize the layers. The successful fabrication of a composition gradient in a difficult-to-process material like the refractory multi-principal element alloy system MoNbTaWHfx shows the utility of this approach for high-throughput screening of large material composition spaces.
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(This article belongs to the Special Issue Advances in Field-Assisted Processing of Metallic Materials: Experiments and Simulations)
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Influence of Various Processing Routes in Additive Manufacturing on Microstructure and Monotonic Properties of Pure Iron—A Review-like Study
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Christof J. J. Torrent, Seyed Vahid Sajadifar, Gregory Gerstein, Julia Richter and Thomas Niendorf
Metals 2024, 14(5), 557; https://doi.org/10.3390/met14050557 - 8 May 2024
Abstract
Additive manufacturing processes have attracted broad attention in the last decades since the related freedom of design allows the manufacturing of parts with unique microstructures and unprecedented complexity in shape. Focusing on the properties of additively manufactured parts, major efforts are made to
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Additive manufacturing processes have attracted broad attention in the last decades since the related freedom of design allows the manufacturing of parts with unique microstructures and unprecedented complexity in shape. Focusing on the properties of additively manufactured parts, major efforts are made to elaborate process-microstructure relationships. For instance, the inevitable thermal cycling within the process plays a significant role in microstructural evolution. Various driving forces contribute to the final grain size, boundary character, residual stress state, etc. In the present study, the properties of commercially pure iron processed on three different routes, i.e., hot rolling as a reference, electron powder bed fusion, and laser powder bed fusion, using different raw materials as well as process conditions, are compared. The manufacturing of the specimens led to five distinct microstructures, which differ significantly in terms of microstructural features and mechanical responses. Using optical and electron microscopy as well as transmission electron microscopy, the built specimens were explored in various states of a tensile test in order to reveal the microstructural evolution in the course of quasistatic loading. The grain size is found to be most influential in enhancing the material’s strength. Furthermore, substructures, i.e., low-angle grain boundaries, within the grains play an important role in terms of the homogeneity of strain distribution. On the contrary, high-angle grain boundaries are found to be regions of strain localization. In summary, a holistic macro-meso-micro-nano investigation is performed to evaluate the behavior of these specific microstructures.
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(This article belongs to the Section Additive Manufacturing)
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Open AccessArticle
An ANN Hardness Prediction Tool Based on a Finite Element Implementation of a Thermal–Metallurgical Model for Mild Steel Produced by WAAM
by
Jun Cheng, Yong Ling and Wim De Waele
Metals 2024, 14(5), 556; https://doi.org/10.3390/met14050556 - 8 May 2024
Abstract
WAAM has emerged as a promising technique for manufacturing medium- and large-scale metal parts due to its high material deposition efficiency and automation level. However, its high heat accumulation and complex thermal evolution strongly affect the resulting microstructures and mechanical properties. The heterogeneous
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WAAM has emerged as a promising technique for manufacturing medium- and large-scale metal parts due to its high material deposition efficiency and automation level. However, its high heat accumulation and complex thermal evolution strongly affect the resulting microstructures and mechanical properties. The heterogeneous and unpredictable nature of these properties hinder the widespread application of WAAM in the steel construction industry. In this study, an artificial neural network (ANN) hardness model is developed, based on a thermal–metallurgical model for mild steel. The objective is to establish non-linear relationships between the input process parameters and the desired output, i.e., hardness. The thermal–metallurgical model utilizes a well-distributed heat source model, a death-and-birth algorithm, and a metallurgical model to simulate the temperature field and to calculate the microstructure phase fraction. The temperature prediction errors at four thermocouple positions are mostly below 20%. Because of the limited experimental data, twenty-five simulation experiments are performed using the L25 orthogonal array based on the Taguchi method. The analysis of variance (ANOVA) reveals that the travel speed has the greatest impact on hardness. With the dataset from the thermal–metallurgical model, an ANN model to predict hardness is developed. A comparison to experimental data shows excellent performance and accuracy, with the Mean Absolute Percentage Error (MAPE) of ANN predictions within 10% of the targeted hardness.
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(This article belongs to the Section Additive Manufacturing)
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Open AccessArticle
Finite Element Analysis and Experimental Verification of Thermal Fatigue of W-PFM with Stacked Structure
by
Chao Qi, Yanfei Qi, Hanfeng Song, Xiao Wang, Shanqu Xiao and Bo Wang
Metals 2024, 14(5), 555; https://doi.org/10.3390/met14050555 - 8 May 2024
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As the prime candidate for plasma-facing materials (PFM), the response of tungsten (W) to thermal shock loads is an important research topic for future fusion devices. Under heat loads, the surface of tungsten plasma-facing materials (W-PFM) can experience thermal damage, including brittle cracking
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As the prime candidate for plasma-facing materials (PFM), the response of tungsten (W) to thermal shock loads is an important research topic for future fusion devices. Under heat loads, the surface of tungsten plasma-facing materials (W-PFM) can experience thermal damage, including brittle cracking and fatigue cracks. Therefore, exploring solutions for thermal damage of W-PFM remains one of the current research focuses. We propose a novel approach to mitigate thermal radiation damage in PFM, namely, the stacked structure W-PFM. The surface thermal stress distribution of the stacked structure W-PFM under heat loads was simulated and analyzed by the finite element method. As the foil thickness decreases, both the peak thermal stresses in the normal direction (ND) and rolling direction (RD) decrease. When the thickness decreases to a certain value, the peak thermal stress in the RD decreases to about 1384 MPa and no longer decreases; while the peak thermal stress in the ND approaches 0 MPa and can be neglected. In the range of approximately 5–100 mm, the accumulated equivalent plastic strain decreases sharply as the thickness decreases; in other thickness ranges, it decreases slowly. Thermal fatigue experiments were conducted on the stacked structure W composed of W foils with different thicknesses and bulk W using an electron beam facility. The samples were applied with a power density of 30 MW/m2 for 10,000 and 20,000 pulses. The cracks on the surface of the stacked structure W extended along the ND direction, while on the surface of bulk W, besides the main crack in the ND direction, a crack network also formed. The experimental results were consistent with finite element simulations. When the pulse number was 10,000, as the thickness of the W foil decreased, the number and width of the cracks on the surface of the stacked structure W decreased. Only four small cracks were present on the surface of stacked structure W (0.05 mm). When the pulse number increased to 20,000, the plastic deformation and number of cracks on the surface of all samples increased. However, the stacked structure W (0.05 mm) only added one small crack and had the smallest surface roughness (Ra = 1.536 μm). Quantitative analysis of the fatigue cracks showed that the stacked structure W-PFM (0.05 mm) exhibited superior thermal fatigue performance.
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Open AccessArticle
Development of Neural Networks to Study Flow Behavior of Medium Carbon Microalloyed Steel during Hot Forming
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Anas Al Omar, Pau Català, Jose Ignacio Alcelay and Esteban Peña
Metals 2024, 14(5), 554; https://doi.org/10.3390/met14050554 - 8 May 2024
Abstract
In the present article, the application of an artificial neural network (ANN) model whose function is the development of plastic instability maps of a medium carbon microalloyed steel during the hot forming process is studied. Secondly, we proceed to create another ANN capable
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In the present article, the application of an artificial neural network (ANN) model whose function is the development of plastic instability maps of a medium carbon microalloyed steel during the hot forming process is studied. Secondly, we proceed to create another ANN capable of providing the recrystallized grain size in the steady state resulting from forming deformation. We start from the experimental data of a medium carbon microalloyed steel obtained by hot compression tests with strain rates that vary between 10−4 s−1 and 3 s−1 and in a range of temperatures between 900 °C and 1150 °C. These experimental data are used to train the proposed ANN and obtain flow curves. Finally, the processing maps are developed by applying the dynamic materials model (DMM), according to which the safe hot forming domains and the plastic instability domains of the studied material are delineated. The comparison between the ANN and the experimental maps is carried out. It is ascertained that the optimal regions of forging in the ANN maps coincide with those obtained in the experimental maps. In addition, a study of the influence of the microstructure on the behavior of the studied steel during hot forming is carried out.
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(This article belongs to the Section Metal Casting, Forming and Heat Treatment)
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Overview: Machine Learning for Segmentation and Classification of Complex Steel Microstructures
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Martin Müller, Marie Stiefel, Björn-Ivo Bachmann, Dominik Britz and Frank Mücklich
Metals 2024, 14(5), 553; https://doi.org/10.3390/met14050553 - 7 May 2024
Abstract
The foundation of materials science and engineering is the establishment of process–microstructure–property links, which in turn form the basis for materials and process development and optimization. At the heart of this is the characterization and quantification of the material’s microstructure. To date, microstructure
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The foundation of materials science and engineering is the establishment of process–microstructure–property links, which in turn form the basis for materials and process development and optimization. At the heart of this is the characterization and quantification of the material’s microstructure. To date, microstructure quantification has traditionally involved a human deciding what to measure and included labor-intensive manual evaluation. Recent advancements in artificial intelligence (AI) and machine learning (ML) offer exciting new approaches to microstructural quantification, especially classification and semantic segmentation. This promises many benefits, most notably objective, reproducible, and automated analysis, but also quantification of complex microstructures that has not been possible with prior approaches. This review provides an overview of ML applications for microstructure analysis, using complex steel microstructures as examples. Special emphasis is placed on the quantity, quality, and variance of training data, as well as where the ground truth needed for ML comes from, which is usually not sufficiently discussed in the literature. In this context, correlative microscopy plays a key role, as it enables a comprehensive and scale-bridging characterization of complex microstructures, which is necessary to provide an objective and well-founded ground truth and ultimately to implement ML-based approaches.
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Open AccessArticle
Investigation of the Influence of Alloy Atomic Doping on the Properties of Cu-Sn Alloys Based on First Principles
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Zongfan Wei, Jiaying Chen, Jingteng Xue, Nan Qu, Yong Liu, Ling Sun, Yuchen Xiao, Baoan Wu, Jingchuan Zhu and Huiyi Tang
Metals 2024, 14(5), 552; https://doi.org/10.3390/met14050552 - 7 May 2024
Abstract
In order to design Cu-Sn alloys with excellent overall performance, the structural stability, mechanical properties, and electronic structure of X-doped Cu-Sn alloys were systematically calculated using first-principles calculations. The calculation results of the cohesive energy indicate that the Cu-Sn-X structures formed by X
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In order to design Cu-Sn alloys with excellent overall performance, the structural stability, mechanical properties, and electronic structure of X-doped Cu-Sn alloys were systematically calculated using first-principles calculations. The calculation results of the cohesive energy indicate that the Cu-Sn-X structures formed by X atoms (X = Ag, Ca, Cd, Mg, Ni, Zr) doping into Cu-Sn can stably exist. The Cu-Sn-Ni structure is the most stable, with a cohesive energy value of −3.84 eV. Doping of X atoms leads to a decrease in the bulk modulus, Possion’s ratio and B/G ratio. However, doping Ag and Ni atoms can improve the shear modulus, Young’s modulus, and strain energy of the dislocation. The doping of Ni has the highest enhancement on shear modulus, Young’s modulus, and strain energy of the dislocation, with respective values as follows: 63.085 GPa, 163.593 GPa, and 1.689 W/J· . The analysis of electronic structure results shows that the covalent bond between Cu and X is the reason for the performance differences in Cu-Sn-X structures.
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(This article belongs to the Section Computation and Simulation on Metals)
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Numerical Simulation and Experimental Verification of Hot Roll Bonding of 7000 Series Aluminum Alloy Laminated Materials
by
Wei Xu, Chengdong Xia and Chengyuan Ni
Metals 2024, 14(5), 551; https://doi.org/10.3390/met14050551 - 7 May 2024
Abstract
In the present study, the hot roll bonding process of 7000 series aluminum alloy laminated materials was numerically simulated and investigated using the finite element method, and the process parameters were experimentally verified by properties testing and microstructure analysis after hot roll bonding.
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In the present study, the hot roll bonding process of 7000 series aluminum alloy laminated materials was numerically simulated and investigated using the finite element method, and the process parameters were experimentally verified by properties testing and microstructure analysis after hot roll bonding. In the roll bonding process of aluminum alloy laminated materials, the effects of the intermediate layer, pass reduction ratio, rolling speed and thickness ratio of component layers were studied. The results of finite element simulations showed that the addition of a 701 intermediate layer in the hot roll bonding process could effectively coordinate the deformation of the 705 layer and 706 layer and prevented the warping of the laminated material during hot rolling. It is recommended to use a multi-pass rolling process with small deformation and high speed, and the recommended rolling reduction ratio is 20%~30%, the hot rolling speed is 1.5~2.5 m/s and the thickness ratio of the 705 layer and 706 layer is about 1:5. Based on the above numerical results, five-layer and seven-layer 7000 series aluminum alloy laminated materials were prepared by the hot roll bonding process. The results showed that metallurgical bonding was realized between each component layer, and no delamination was observed from the tensile fracture between the interfaces of component layers. The tensile strength of the prepared laminated materials decreased with the increase in the thickness ratio of the 705 layer, and the bonding strengths of the laminated materials were in the range of 88–99 MPa. The experimental results verified the rationality of the process parameters recommended by the numerical simulations in terms of warping and delamination prevention.
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(This article belongs to the Special Issue Numerical Simulation and Experimental Research of Metal Rolling)
Open AccessArticle
Role of Semiconductive Property on Selective Cementation Mechanism of Iron Oxides to Gold in Galvanic Interaction with Zero-Valent Aluminum from Gold–Copper Ammoniacal Thiosulfate Solutions
by
Joshua Zoleta, Kosei Aikawa, Nako Okada, Ilhwan Park, Mayumi Ito, Yogarajah Elakneswaran and Naoki Hiroyoshi
Metals 2024, 14(5), 550; https://doi.org/10.3390/met14050550 - 7 May 2024
Abstract
Iron oxides (hematite, Fe2O3, and magnetite, Fe3O4), previously used as electron mediators in the galvanic system with zero-valent aluminum (ZVAl), have been shown to recover Au upon cementation in Au–Cu ammoniacal thiosulfate media selectively, and
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Iron oxides (hematite, Fe2O3, and magnetite, Fe3O4), previously used as electron mediators in the galvanic system with zero-valent aluminum (ZVAl), have been shown to recover Au upon cementation in Au–Cu ammoniacal thiosulfate media selectively, and this warrants further investigation. This research is focused on investigating the role of the semiconductive properties of metal oxides by performing a cementation experiment by mixing 0.15 g of electron mediators (Fe3O4, Fe2O3, TiO2 (anatase and rutile)) and 0.15 g of zero-valent aluminum powder as an electron donor in various electrochemical experiments. The results revealed that upon the cementation experiment, synthetic Fe2O3 and Fe3O4 were consistently able to selectively recover Au at around 90% and Cu at around 20%. Compared to activated carbon (AC), TiO2, in anatase and rutile forms, obtained selective recovery of gold, but the recovery was utterly insignificant compared to that of iron oxides, obtaining an average of 93% Au and 63% Cu recovery. The electrochemical and surface analysis supports the results obtained upon the cementation process, where TiO2, upon cyclic voltammetry (CV), obtained two reduction peaks centered at −1.0 V and −0.5 V assigned to reducing Au and Cu ions, respectively. Furthermore, various electrochemical impedance spectroscopic analyses revealed that the flat band potential obtained in the Mott–Schottky plot is around −1.0 V and −0.2 V for iron oxides and titanium oxides, respectively, suggesting that the electrons travel from semiconductor interface to electrolyte interface, and electrons are accessible only to Au ions in the electrolyte interface (reduction band edge around −1.0 V). The determination of this selective cementation mechanism is one of a kind. It has been proposed that the semiconductive properties of Fe2O3, Fe3O4, and, by configuring their relative energy band diagram, the travel of electrons from the iron oxide–electrolyte interface facilitate the selective cementation towards Au(S2O3)23+ ions in gold–copper ammoniacal thiosulfate solutions.
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(This article belongs to the Section Extractive Metallurgy)
Open AccessArticle
Comparison of STP and TP Modes of Wire and Arc Additive Manufacturing of Aluminum–Magnesium Alloys: Forming, Microstructures and Mechanical Properties
by
Qiang Zhu, Ping Yao and Huan Li
Metals 2024, 14(5), 549; https://doi.org/10.3390/met14050549 - 7 May 2024
Abstract
Aluminum–magnesium (Al–Mg) alloys, known for their lightweight properties, are extensively utilized and crucial in the advancement of wire and arc additive manufacturing (WAAM) for direct high-quality printing—a focal point in additive manufacturing research. This study employed 1.2 mm ER5356 welding wire as the
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Aluminum–magnesium (Al–Mg) alloys, known for their lightweight properties, are extensively utilized and crucial in the advancement of wire and arc additive manufacturing (WAAM) for direct high-quality printing—a focal point in additive manufacturing research. This study employed 1.2 mm ER5356 welding wire as the raw material to fabricate two sets of 30-layer thin-walled structures. These sets were manufactured using two distinct welding modes, speed-twin pulse (STP) and twin pulse (TP). Comparative evaluations of the surface quality, microstructures, and mechanical properties of the two sets of samples indicated that both the STP and TP modes were suitable for the WAAM of Al–Mg alloys. Analyses of grain growth in the melt pools of both sample sets revealed a non-preferential grain orientation, with a mixed arrangement of equiaxed and columnar grains. The STP mode notably achieved a refined surface finish, a reduced grain size, and a slight increase in tensile strength compared to the TP mode. From the comparison of the tensile data at the bottom, middle, and top of the two groups of samples, the additive manufacturing process in the STP mode was more stable.
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(This article belongs to the Special Issue Additive Manufacturing of Light Metal Alloys)
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Analysis of the Influence of Contact Stress on the Fatigue of AD180 High-Carbon Semi-Steel Roll
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Yaxing Liu, Lixin Liu, Qian Cheng, Haipeng Hou, Zehua Zhang and Zhongkai Ren
Metals 2024, 14(5), 548; https://doi.org/10.3390/met14050548 - 6 May 2024
Abstract
In this study, to investigate the problem of contact fatigue and the damage mechanism of an AD180 high-carbon semi-steel roll, rolling contact fatigue tests were conducted using specimens cut from the periphery of a roll ring. These specimens were characterized under different contact
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In this study, to investigate the problem of contact fatigue and the damage mechanism of an AD180 high-carbon semi-steel roll, rolling contact fatigue tests were conducted using specimens cut from the periphery of a roll ring. These specimens were characterized under different contact stresses using SEM, a profile system, an optical microscope, and a Vickers hardness tester. The results indicates that the main forms of fatigue damage of an AD180 high-carbon semi-steel roll are peeling, pitting corrosion, and plowing. Moreover, the surface of the roll exhibits delamination and plastic deformation characteristics under high contact stress. Meanwhile, the size and depth of peeling, as well as the amount of pitting corrosion, increase with the contact stress. Peeling is mainly caused by a crack that originates at the edge of the specimen surface and propagates along the pearlite structure and the interface between pearlite and cementite. High contact stress can lead to an increase in the crack propagation depth and angle, resulting in the formation of larger peeling. Under cyclic loading, the near-surface microstructure of the specimen hardens due to grain refinement and dislocation strengthening, and the depth of the hardened layer increases with the increase in contact stress. When the contact stress reaches 1400 MPa, the near surface structure of the specimen changes from pearlite to troostite.
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(This article belongs to the Special Issue Numerical Simulation of Metal Forming Process)
Open AccessArticle
Microstructure and Phase Composition of Novel Crossover Al-Zn-Mg-Cu-Zr-Y(Er) Alloys with Equal Zn/Mg/Cu Ratio and Cr Addition
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Maria V. Glavatskikh, Ruslan Yu. Barkov, Leonid E. Gorlov, Maxim G. Khomutov and Andrey V. Pozdniakov
Metals 2024, 14(5), 547; https://doi.org/10.3390/met14050547 - 6 May 2024
Abstract
The effect of 0.2%Cr addition on the structure, phase composition, and mechanical properties of the novel cast and wrought Al-2.5Zn-2.5Mg-2.5Cu-0.2Zr-Er(Y) alloys were investigated in detail. Chromium is distributed between primary crystals (5.7–6.8%) of the intermetallic phase and the aluminum solid solution (0.2%) (Al).
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The effect of 0.2%Cr addition on the structure, phase composition, and mechanical properties of the novel cast and wrought Al-2.5Zn-2.5Mg-2.5Cu-0.2Zr-Er(Y) alloys were investigated in detail. Chromium is distributed between primary crystals (5.7–6.8%) of the intermetallic phase and the aluminum solid solution (0.2%) (Al). The primary crystals contain for the main part Cr, Ti, Er(Y). The experimental phase composition is in good correlation with the thermodynamic computation data. The micron-sized solidification origin phases (Al8Cu4Er(or Y) and Mg2Si) and supersaturated (Al) with nano-sized Al3(Zr,Ti) and E (Al18Mg3Cr2) precipitates are presented in the microstructure of the novel alloys after solution treatment. The nucleation of η (MgZn2) (0.5%), S (Al2CuMg) (0.4%), and T (Al,Zn,Mg,Cu) (8.8%) phase precipitates at 180 °С, providing the achievement of a maximum hardness of 135 HV in the Al2.5Zn2.5Mg2.5CuYCr alloy. The corrosion potential of the novel alloy is similar to the Ecor of the referenced alloy, but the corrosion current density (0.68–0.98 µA/sm2) is still significantly lower due to the formation of E (Al18Mg3Cr2) precipitates and S phase precipitates of the aging origin, in addition to the T phase. The formation of E (Al18Mg3Cr2) precipitates under the solution treatment provides a lower proportion of recrystallized grains (2.5–5% vs. 22.4–25.1%) and higher hardness (110 HV vs. 85–95 HV) in the Cr-rich alloys compared to the referenced alloys. Solution treated, hot and cold rolled, recrystallized, water quenched and aged at 210 °С alloys demonstrate an excellent microstructure stability and tensile properties: YS = 299–300 MPa, UTS = 406–414 MPa, and El. = 9–12.3%.
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Open AccessArticle
The Effects of Si Substitution with C on the Amorphous Forming Ability, Thermal Stability, and Magnetic Properties of an FeSiBPC Amorphous Alloy
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Wenzhong Zhu, Xiaoqian Jiang, Chen Chen, Shaojie Wu, Yongfu Cai, Fushan Li, Ran Wei and Tan Wang
Metals 2024, 14(5), 546; https://doi.org/10.3390/met14050546 - 4 May 2024
Abstract
The industrialization of Fe-based amorphous alloys with high a saturation magnetic flux density (Bs) has been limited so far due to their inadequate amorphous forming ability (AFA). In this study, the effects of substituting Si with C on the AFA,
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The industrialization of Fe-based amorphous alloys with high a saturation magnetic flux density (Bs) has been limited so far due to their inadequate amorphous forming ability (AFA). In this study, the effects of substituting Si with C on the AFA, thermal stability, and magnetic properties of Fe82Si6−xB9P3Cx (x = 0–6) alloys were systematically investigated. The experimental results demonstrate that the AFA, thermal stability, and soft magnetic properties can be significantly enhanced by the addition of C. Specifically, at a copper wheel velocity of 40 m/s, the Fe82Si6−xB9P3Cx (x = 2, 3, 4, 5 and 6) alloy ribbons exhibit a fully amorphous structure in the as-spun state. The activation energy required for the α-Fe phase crystallization process in Fe82Si6−xB9P3Cx (x = 0, 2, 4, and 6) alloys is determined to be 326.74, 390.69, 441.06, and 183.87 kJ/mol, respectively. Among all of the compositions studied, the Fe82Si4B9P3C2 alloy exhibits optimized soft magnetic properties, including a low coercivity (Hc) of 1.7 A/m, a high effective permeability (μe) of 10608 (f = 1 kHz), and a relatively high Bs of 1.61 T. These improvements may be attributed to a more homogeneous and optimized magnetic domain structure being achieved through proper C addition. This work holds significant implications for the advancement of Fe-based soft magnetic amorphous alloys with high Bs.
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(This article belongs to the Section Entropic Alloys and Meta-Metals)
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Open AccessArticle
The Effect of Misalignment on Stress Concentration and Fatigue Life for Circumferential Weld Joints of Pipeline
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Niantao Zhang, Caiyan Deng, Zhichen Lin, Zhijiang Wang and Shaojie Wu
Metals 2024, 14(5), 545; https://doi.org/10.3390/met14050545 - 4 May 2024
Abstract
Misalignment has a significant impact on the fatigue performance of circumferential weld joints in pipelines, which can significantly reduce the fatigue life. Misalignment generates a structural stress concentration on the pipeline, which proportionally reduces its fatigue strength. Moreover, due to the misalignment, the
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Misalignment has a significant impact on the fatigue performance of circumferential weld joints in pipelines, which can significantly reduce the fatigue life. Misalignment generates a structural stress concentration on the pipeline, which proportionally reduces its fatigue strength. Moreover, due to the misalignment, the reinforcement of the root and the transition angle of the pipeline inwall are significantly reduced, increasing its notch stress concentration factor and further reducing its fatigue performance. This work investigates the effect of misalignment on stress concentration in the circumferential welds of pipelines, and it is used to predict the fatigue life. The structural stress method is proposed in the present work, and finite element analysis technology with Abaqus is used to calculate the structural stress concentration factor kj at the root-pass toe of misaligned circumferential weld joints, and a formula for the relationship between the structural stress concentration factor kj and the misalignment is established. The total stress concentration factor k of weld joints with different misalignments under several welding processes are calculated, and are compared with the structural stress concentration factor kj. The fatigue test data of weld joints with different misalignments are studied, and it is shown that the fatigue performance could be predicted by the fitting result.
Full article
(This article belongs to the Special Issue Offshore Engineering Steel: Welding Performance and Microstructure Analysis)
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Open AccessArticle
Theoretical Modeling and Mechanical Characterization at Increasing Temperatures under Compressive Loads of Al Core and Honeycomb Sandwich
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Alessandra Ceci, Girolamo Costanza and Maria Elisa Tata
Metals 2024, 14(5), 544; https://doi.org/10.3390/met14050544 - 3 May 2024
Abstract
This work investigates the mechanical behavior under out-of-plane compression of the Al core and honeycomb sandwich at increasing temperatures of up to 300 °C. After the first introductive theoretical modeling on room-temperature compressive behavior, the experimental results at increasing temperatures up to 300
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This work investigates the mechanical behavior under out-of-plane compression of the Al core and honeycomb sandwich at increasing temperatures of up to 300 °C. After the first introductive theoretical modeling on room-temperature compressive behavior, the experimental results at increasing temperatures up to 300 °C are presented and discussed. The analysis of the results shows that peak stress, plateau stress, and specific absorbed energy gradually decrease as the temperature increases. The final densification occurs always at the same strain level (around 75%). Sandwich honeycomb test temperatures have been limited to 200 °C for bonding problems of the skin to the sandwich due to the glue. The experimental and modeling results agree well at room temperature as well at increasing temperatures. The results can provide useful information to choose base materials for greater energy absorption at increasing temperatures.
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(This article belongs to the Special Issue Innovations in Lightweight Materials for Automotive and Aerospace Applications)
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Open AccessFeature PaperArticle
Effect of Temperature and NaClO on the Corrosion Behavior of Copper in Synthetic Tap Water
by
Fei Sun, Na Zhang, Shen Chen and Moucheng Li
Metals 2024, 14(5), 543; https://doi.org/10.3390/met14050543 - 3 May 2024
Abstract
The corrosion behavior of copper was investigated in synthetic tap water with and without sodium hypochlorite (NaClO) at different temperatures during immersion for 70 d by using scanning electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical measurement techniques. The weight loss corrosion rate
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The corrosion behavior of copper was investigated in synthetic tap water with and without sodium hypochlorite (NaClO) at different temperatures during immersion for 70 d by using scanning electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical measurement techniques. The weight loss corrosion rate and pit depth of copper first increase and then decrease with the change in solution temperature from 25 to 80 °C. This is mainly related to the corrosion products formed on the copper surface. The main corrosion products change from Cu2O and Cu2(OH)2CO3 to CuO with the increase in solution temperature. The presence of 3 ppm NaClO slightly increases the weight loss corrosion rate and pit depth of copper under all temperatures except for 50 °C and reduces the temperature of the maximum corrosion rate from 50 to 40 °C. Free chlorine reduction accelerates the cathodic reaction of the corrosion process.
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(This article belongs to the Section Corrosion and Protection)
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Open AccessArticle
Al and A356 Alloy Foam Castings Modified with Low Concentrations of Nano-Sized Particles: Structural Study and Compressive Strength Tests
by
Rositza Dimitrova, Tatiana Simeonova, Boyko Krastev, Angel Velikov, Veselin Petkov and Valentin Manolov
Metals 2024, 14(5), 542; https://doi.org/10.3390/met14050542 - 2 May 2024
Abstract
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Aluminum and A356 alloy foam castings are produced using a melt-foaming method. Prior to foaming, the melt is modified with nano-sized particles (SiC, TiN, or Al2O3). The nano-sized particles are mixed with micro-sized Al particles, which are ultrasonically treated
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Aluminum and A356 alloy foam castings are produced using a melt-foaming method. Prior to foaming, the melt is modified with nano-sized particles (SiC, TiN, or Al2O3). The nano-sized particles are mixed with micro-sized Al particles, which are ultrasonically treated and hot-extruded. Thus, the so-called “modifying nano-composition” is obtained. The resulting compositions are introduced into the melt of the Al foam at the following mass concentrations of nanoparticles: SiC: 0.038 wt. %; TiN: 0.045 wt. %; and Al2O3: 0.046 wt. %. For the A356 foam, we use the following concentrations: SiC: 0.039 wt. %; TiN: 0.052 wt. %; and Al2O3: 0.086 wt. %. The macrostructure of the foam castings is investigated by CT scanning and 3D analysis. The pore size distributions and accumulative fraction dependencies are determined for all samples. The microstructure of the foam castings is investigated by SEM-EDS analysis. The results confirmed the presence of individual nano-sized particles, as well as clusters of particles in foam walls. The conducted compression tests show a significant increase in the plateau stress (up to 237%) of the modified aluminum foam castings compared to non-modified castings. However, a similar effect of the nano-compositions on A356 alloy foam castings is not observed. The obtained results show that the above-indicated concentrations of nanoparticles can positively influence the mechanical properties of aluminum foam castings. The novelty of the current study is two-fold: (1) such low concentrations of added nanoparticles have never been used before to alter Al foam’s properties, and (2) an original method of introducing the nanoparticles into the melt is applied in the form of nano-compositions.
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Open AccessArticle
Revealing the Enhancement Mechanism of Laser Cutting on the Strength–Ductility Combination in Low Carbon Steel
by
Jie Chen, Feiyue Tu, Pengfei Wang and Yu Cao
Metals 2024, 14(5), 541; https://doi.org/10.3390/met14050541 - 2 May 2024
Abstract
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The strength–ductility mechanism of the low-carbon steels processed by laser cutting is investigated in this paper. A typical gradient-phased structure can be obtained near the laser cutting surface, which consists of a laser-remelted layer (LRL, with the microstructure of lath bainite + granular
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The strength–ductility mechanism of the low-carbon steels processed by laser cutting is investigated in this paper. A typical gradient-phased structure can be obtained near the laser cutting surface, which consists of a laser-remelted layer (LRL, with the microstructure of lath bainite + granular bainite) and heat-affected zone (HAZ). As the distance from the laser cutting surface increases, the content of lath martensite decreases in the HAZ, which is accompanied by a rise in the content of ferrite. Considering that the microstructures of the LRL and HAZ are completely different from the base metal (BM, ferrite + pearlite), a significant strain gradient can be inevitably generated by the remarkable microhardness differences in the gradient-phased structure. The hetero-deformation-induced strengthening and hardening will be produced, which is related to the pileups of the geometrically necessary dislocations (GNDs) that are generated to accommodate the strain gradient near interfaces. Plural phases of the HAZ can also contribute to the increment of the hetero-deformation-induced strengthening and hardening during deformation. Due to the gradient-phased structure, the low carbon steels under the process of laser cutting have a superior combination of strength and ductility as yield strength of ~487 MPa, tensile strength of ~655 MPa, and total elongation of ~32.7%.
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Open AccessArticle
Effect of Force and Heat Coupling on Machined Surface Integrity and Fatigue Performance of Superalloy GH4169 Specimens
by
Xun Li, Ruijie Gou and Ning Zhang
Metals 2024, 14(5), 540; https://doi.org/10.3390/met14050540 - 2 May 2024
Abstract
GH4169 is one of the key materials used to manufacture high-temperature load-bearing parts for aero-engines, and the surface integrity of these parts in service conditions significantly affects their high-temperature fatigue performance. Under a coupling effect of high temperature and alternating load, the evolution
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GH4169 is one of the key materials used to manufacture high-temperature load-bearing parts for aero-engines, and the surface integrity of these parts in service conditions significantly affects their high-temperature fatigue performance. Under a coupling effect of high temperature and alternating load, the evolution process of the machined surface integrity index of superalloy GH4169 specimens was studied, and fatigue performance tests at 20 °C, 450 °C, and 650 °C were carried out to analyze the primary factors affecting the high-temperature fatigue performance of specimens. The results indicated that the surface roughness of specimens remained essentially unchanged. However, the value of surface residual stress decreased significantly, with a release of more than 60% at the highest temperature. At 650 °C, the surface microhardness increased, while the degree of surface plastic deformation decreased under alternating loads. Simultaneously, when the surface roughness was less than Ra 0.4 μm, surface microhardness was the main factor affecting the high-temperature fatigue performance of specimens. The influence of surface microhardness on low-cycle fatigue performance was not consistent with that on high-cycle fatigue performance. The latter increased monotonically, whereas the former initially increased and then decreased with increasing surface microhardness.
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(This article belongs to the Special Issue Advances in Lightweight Alloys)
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