Metals

16 pages, 24622 KiB

Open AccessArticle

Welding Pores Evolution in the Detector Bottom-Locking Structure Fabricated Using the Hybrid Pulsed Arc–Laser Method

by Yonglong Yu, Jianzhou Xu, Xiaoquan Yu, Liang Guo, Tongyu Zhu and Ding Fan

Metals 2024, 14(12), 1469; https://doi.org/10.3390/met14121469 - 23 Dec 2024

Viewed by 466

The welding of the bottom-locking structure in a detector receptacle plays an essential role in ensuring the safety of nuclear equipment. A pulsed TIG–laser hybrid welding method is proposed to address the problem of welding pores in locking structural parts. The effects of [...] Read more.

The welding of the bottom-locking structure in a detector receptacle plays an essential role in ensuring the safety of nuclear equipment. A pulsed TIG–laser hybrid welding method is proposed to address the problem of welding pores in locking structural parts. The effects of the pulse frequency on the escape of porosity and of porosity on the mechanical properties of the hybrid welding joint were investigated. The results were compared to those of direct current (0 Hz), showing that the pulse frequency affects the stability of the arc. With an increase in pulse frequency, the grain size of the fusion zone gradually decreases, and the flow in the middle area of the molten pool increases. This subjects bubbles in the molten pool to a thrust force, which causes the bubbles to escape to the surface of the molten pool. Compared with 0 Hz, the tensile strength of the joint increased by 67%. This provides a new solution for obtaining reliable welded joints for the bottom-locking structure of detector storage tanks. Full article

(This article belongs to the Special Issue Microstructure and Mechanical Property Improvement of Welded Metal Joints)

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18 pages, 15215 KiB

Open AccessArticle

Correlation Between Morphology and Crystal Structure of Electrolytically Produced Zinc Dendritic Particles

by Nebojša D. Nikolić, Jelena D. Lović, Vesna M. Maksimović, Nikola S. Vuković, Nenad L. Ignjatović, Predrag M. Živković and Sanja I. Stevanović

Metals 2024, 14(12), 1468; https://doi.org/10.3390/met14121468 - 23 Dec 2024

Viewed by 563

Abstract

The correlation between the morphology and crystal structure of zinc dendritic particles produced by electrolysis from the alkaline electrolyte has been established. Morphology and crystal structure of Zn particles electrodeposited by the potentiostatic regime of electrolysis at overpotentials inside (−100 and −160 mV) [...] Read more.

The correlation between the morphology and crystal structure of zinc dendritic particles produced by electrolysis from the alkaline electrolyte has been established. Morphology and crystal structure of Zn particles electrodeposited by the potentiostatic regime of electrolysis at overpotentials inside (−100 and −160 mV) and outside (−220, −280, and −340 mV) the plateau of the limiting diffusion current density were characterized by scanning electron microscope (SEM) and by X-ray diffraction (XRD), respectively. The particle size distribution (PSD) was performed in order to determine the dependency of the size of dendritic particles on applied electrolysis overpotential. With increasing the overpotential of electrolysis, the shape of particles changed from irregular forms denoted as precursors of dendrites to various forms of dendrites, while the size of the particles simultaneously decreased. All types of Zn dendrites exhibited the strong (002) preferred orientation, while the precursors of dendrites exhibited (101)(002) preferred orientation. The development of strong (002) preferred orientation was explained and discussed by making an analogy with the electrolytic production of lead dendrites from the concentrated nitrate electrolyte. Although zinc and lead belong to different types of crystal lattice (Pb-face-centered cubic type and Zn-hexagonal close-packed type), they have a common characteristic that is manifested by the strong preferred orientation in the crystal plane with the lowest surface energy. Full article

(This article belongs to the Special Issue New Trends of Powder Engineering and Additive Manufacturing (Editorial Board Members’ Collection Series))

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14 pages, 4991 KiB

Open AccessArticle

Study on Reduction Mechanism of Iron Oxide by Industrial Lignin

by Dongwen Xiang, Qiang Zhang, Guoqing Wu, Yajie Wang, Dong Li, Qinghua Zhang and Huaxin Hu

Metals 2024, 14(12), 1467; https://doi.org/10.3390/met14121467 - 23 Dec 2024

Viewed by 442

Abstract

To effectively utilize industrial lignin, a large amount of waste produced by the pulp and paper industry, this paper primarily explores its potential as a substitute for coal-based reducing agents in the reduction of iron oxides. The weight change, phase change, and activation [...] Read more.

To effectively utilize industrial lignin, a large amount of waste produced by the pulp and paper industry, this paper primarily explores its potential as a substitute for coal-based reducing agents in the reduction of iron oxides. The weight change, phase change, and activation energy change during the reduction of iron oxide by industrial lignin were characterized using detection methods such as TG-DTG-DSC, XRD, and SEM. The results show that the maximum weight loss rate of industrial lignin reducing iron oxide is (4.52%·min⁻¹) > Lu’an anthracite (2.01%·min⁻¹) > Shenmu bituminous coal (1.57%·min⁻¹). The activation energy variation range during the reduction of Fe₂O₃ by industrial lignin, calculated using the Flynn–Wall–Ozawa (FWO) method, is 241.91~463.51 kJ·mol⁻¹, and the activation energy first decreased, then increased, then decreased slightly with the increase of conversion fraction. There is a coupling effect in the reduction of Fe₂O₃ by industrial lignin. Full article

(This article belongs to the Special Issue Advanced Metal Smelting Technology and Prospects)

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17 pages, 12063 KiB

Open AccessArticle

The CaO Enhanced Defluorination and Air-Jet Separation of Cathode-Active Material Coating for Direct Recycling Li-Ion Battery Electrodes

by Piotr Siwak, Volf Leshchynsky, Emil Strumban, Mircea Pantea, Dariusz Garbiec and Roman Maev

Metals 2024, 14(12), 1466; https://doi.org/10.3390/met14121466 - 23 Dec 2024

Viewed by 524

Abstract

With the rapid growth of the lithium-ion battery (LIBs) market, recycling and re-using end-of-life LIBs to reclaim the critical Li, Co, Ni, and Mn has become an urgent task. Presently, high temperature, strong acid, and alkali conditions are required to extract blended critical [...] Read more.

With the rapid growth of the lithium-ion battery (LIBs) market, recycling and re-using end-of-life LIBs to reclaim the critical Li, Co, Ni, and Mn has become an urgent task. Presently, high temperature, strong acid, and alkali conditions are required to extract blended critical metals (CM) from the typical battery cathode. Hence, there is a need for more effective recycling processes for recycling blended Li, Co, Ni, and their direct regeneration for re-use in LIBs. The goal of the offered paper is the development of recycling technology for degraded battery cathode-active materials based on the thermal decomposition of polyvinylidene fluoride (PVDF) using calcination and air-jet stripping of active materials. The proposed air-jet erosion method of calcined cathode material stripping from Al foil allows for the flexible industry-applicable separation process, which is damage-free for both particles and substrate. The CaO calcination air-jet separation process and equipment can significantly improve the PVDF decomposition and the separation efficiency of the cathode materials. It is demonstrated that low-temperature CaO calcination at 350–450 °C associated with air-jet separation of active material is characterized by low environmental impact, high purity of the recycled material, and low cost as compared to pyro- and hydrometallurgical methods. Full article

(This article belongs to the Special Issue Recovery of Critical Raw Materials from Industrial Wastes by Advanced Methods)

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20 pages, 2661 KiB

Open AccessArticle

Evaluation of the Preg-Robbing Effect in Gold Recovery Using the Carbon-in-Leach Technique: A Comparative Study of Three Reactor Types

by Carlos Ocampo-López, Leidy Rendón-Castrillón, Margarita Ramírez-Carmona and Federico González-López

Metals 2024, 14(12), 1465; https://doi.org/10.3390/met14121465 - 22 Dec 2024

Viewed by 873

Abstract

This study evaluates the preg-robbing effect on gold recovery through a carbon-in-leach process, comparing three reactor types: glass, stainless steel, and stainless steel coated with ceramic resin. Protonated activated carbon (PAcC) and anthracite carbon (PAnC) were used as adsorbents. The results show that [...] Read more.

This study evaluates the preg-robbing effect on gold recovery through a carbon-in-leach process, comparing three reactor types: glass, stainless steel, and stainless steel coated with ceramic resin. Protonated activated carbon (PAcC) and anthracite carbon (PAnC) were used as adsorbents. The results show that PAcC achieved a significantly higher gold adsorption rate of up to 99.87%, compared to PAnC, which achieved a maximum of 66%, mitigating the preg-robbing effect. The stainless steel reactor performed best, with gold recovery rates exceeding 90%, as confirmed by a multi-criteria decision matrix evaluating factors like durability, mechanical strength, and corrosion resistance. A 2⁴⁻¹ fractional factorial design identified key variables for optimal recovery, with aeration of 9.31 L/min, a PAcC pulp density of 2.5 g/L, and the use of Puerto Berrío ore resulting in the highest gold recovery, reaching 18.38 ppm. The mass balance confirmed that gold adsorption on PAcC was the most efficient, leaving less than 0.13% gold in the leachate. These results demonstrate the superiority of PAcC and stainless steel reactors in mitigating the preg-robbing effect, offering an effective solution for scaling up gold recovery processes. Full article

(This article belongs to the Special Issue Separation, Purification and Extraction of Metals from Primary and Secondary Resources)

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36 pages, 8289 KiB

Open AccessReview

On the Use of Green and Blue Laser Sources for Powder Bed Fusion: State of the Art Review for Additive Manufacturing of Copper and Its Alloys

by Mankirat Singh Khandpur, Alberto Giubilini, Luca Iuliano and Paolo Minetola

Metals 2024, 14(12), 1464; https://doi.org/10.3390/met14121464 - 22 Dec 2024

Viewed by 829

Abstract

Additive manufacturing (AM) is a layerwise production process that creates three-dimensional objects according to a digital model. This technology has demonstrated to be a promising alternative to conventional manufacturing methods for various industrial sectors, such as aerospace, automotive, biomedical, and energy. AM offers [...] Read more.

Additive manufacturing (AM) is a layerwise production process that creates three-dimensional objects according to a digital model. This technology has demonstrated to be a promising alternative to conventional manufacturing methods for various industrial sectors, such as aerospace, automotive, biomedical, and energy. AM offers several advantages, like design flexibility, material efficiency, functional integration, and rapid prototyping. As regards metal parts, conventional AM techniques using infrared laser sources face some limitations in processing high-reflectivity and high-conductivity materials or alloys, such as aluminum, copper, gold, and silver. These materials have low absorption of infrared radiation, which results in unstable and shallow melt pools, poor surface quality, and high porosity. To overcome these challenges, green and blue laser sources have been proposed for AM processes. This review provides an overview of the recent developments and applications of green and blue laser sources for powder bed fusion of copper and its alloys, focusing on the effects of process parameters on the melt pool dynamics, microstructure formation, and thermal and electrical properties of the fabricated parts. This review also presents the main applications of AM of copper and its alloys together with potential opportunities for future developments. Full article

(This article belongs to the Special Issue Development of Metallic Material Laser Additive Manufacturing)

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18 pages, 5935 KiB

Open AccessArticle

Numerical Simulations of Stress Intensity Factors and Fatigue Life in L-Shaped Sheet Profiles

by Ferdinand Dömling, Florian Paysan and Eric Breitbarth

Metals 2024, 14(12), 1463; https://doi.org/10.3390/met14121463 - 21 Dec 2024

Viewed by 860

Abstract

The assessment of fatigue cracks is an elementary part of the design process of lightweight structures subject to operational loads. Although angled sheets are standard components in forming technology, fatigue crack growth in geometries like C- and L-sections has been little-studied and is [...] Read more.

The assessment of fatigue cracks is an elementary part of the design process of lightweight structures subject to operational loads. Although angled sheets are standard components in forming technology, fatigue crack growth in geometries like C- and L-sections has been little-studied and is mostly limited to crack growth before the transition through the corner. In this study, fatigue crack propagation is simulated to explore the influence of sheet thickness, corner angle and corner radius on the fatigue life in an L-section. The stress intensity factor (SIF) is derived as the driving force of crack growth over the full crack path. Special attention is paid to the evolution of the SIF in the radius sub-section and its implications on the fatigue life. The results show that the SIF in an angled sheet for given loading conditions and crack lengths cannot be readily approximated by the SIF in an equivalent straightened sheet. The bending angle and radius lead to crack growth retardation or acceleration effects. These findings are important for the design and optimization of forming geometries with regard to fatigue crack growth. Full article

(This article belongs to the Special Issue Fracture and Fatigue of Advanced Metallic Materials)

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15 pages, 2621 KiB

Open AccessArticle

Comparative Analysis of the Corrosion and Mechanical Behavior of an Al-SiC Composite and AA 2024 Alloy Fabricated by Powder Metallurgy for Aeronautical Applications

by Willian Aperador, Jonnathan Aperador and Giovany Orozco-Hernández

Metals 2024, 14(12), 1462; https://doi.org/10.3390/met14121462 - 20 Dec 2024

Viewed by 615

Abstract

This study presents a comparative analysis of the corrosion and mechanical properties of an Al-SiC composite and an AA 2024 aluminum alloy, focusing on their suitability for aeronautical applications. The Al-SiC composite was fabricated using advanced powder metallurgy techniques, incorporating a 20% volume [...] Read more.

This study presents a comparative analysis of the corrosion and mechanical properties of an Al-SiC composite and an AA 2024 aluminum alloy, focusing on their suitability for aeronautical applications. The Al-SiC composite was fabricated using advanced powder metallurgy techniques, incorporating a 20% volume of silicon carbide (SiC) particles, averaging 1.6 µm in size, to enhance its structural and electrochemical performance. Electrochemical evaluations in an aerated 3.5% NaCl solution revealed a significant improvement in the corrosion resistance of the Al-SiC composite. This enhancement is attributed to the cathodic nature of the SiC particles, which promote the formation of a protective aluminum oxide layer, reducing pitting corrosion and preserving the material’s structural integrity. In terms of the mechanical properties, the Al-SiC composite demonstrated a higher yield strength and ultimate tensile strength compared to the AA 2024 alloy. While it exhibited a slightly lower elongation at failure, the composite maintained a favorable balance between strength and ductility. Additionally, the composite showed a higher Young’s modulus indicating improved resistance to deformation under load. These findings underscore the potential of the Al-SiC composite for demanding aerospace applications, offering valuable insights into the development of materials capable of withstanding extreme operational environments. Full article

(This article belongs to the Section Corrosion and Protection)

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10 pages, 10776 KiB

Open AccessArticle

Evolution of Stress Rupture Property for K439B Superalloy During Long-Term Thermal Exposure at 800 °C

by Yidong Wu, Xinghai Qu, Lei Gao, Chaoqian Song, Zhao Dong, Jingyang Chen and Xidong Hui

Metals 2024, 14(12), 1461; https://doi.org/10.3390/met14121461 - 20 Dec 2024

Viewed by 496

Abstract

The K439B superalloy is widely utilized in aeroengine components due to its superior weldability and mechanical performance. Given that the hot-end components of aeroengines typically operate at high temperatures for extended periods, even up to 10,000 h, it is essential to investigate the [...] Read more.

The K439B superalloy is widely utilized in aeroengine components due to its superior weldability and mechanical performance. Given that the hot-end components of aeroengines typically operate at high temperatures for extended periods, even up to 10,000 h, it is essential to investigate the stress rupture properties and deformation mechanisms of K439B alloy after prolonged thermal exposure. In this work, thermal exposure at 800 °C for 6000, 8000, and 10,000 h was conducted for the K439B superalloy. Unlike the samples with aging times less than 6000 h, for the samples aged between 6000 and 10,000 h, the stress rupture life at 815 °C/379 MPa decreased slowly, from 47.3 to 39.1 h. Creep cracks typically originate at metal carbides (MC type) and subsequently propagate along grain boundaries. Notably, the creep deformation mechanism shifts under varying aging conditions. After 6000 h of aging, the deformation mechanism is primarily governed by Orowan bypassing and isolated stacking fault shearing. As the aging period increases further, the γ′ precipitates progressively coarsen, and isolated stacking faults become more prevalent, ultimately reducing the creep resistance of the alloy. Full article

(This article belongs to the Special Issue Microstructure, Tensile Properties and Creep Behavior of Metallic Materials)

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18 pages, 12529 KiB

Open AccessArticle

Crystallographic Texture Evolution of Aluminum Samples with a Rectangular Cross-Section During Equal Channel Angular Pressing Processing

by Andrea Mireles-Ramos and Francisco García-Pastor

Metals 2024, 14(12), 1460; https://doi.org/10.3390/met14121460 - 20 Dec 2024

Viewed by 602

Abstract

The evolution of the crystallographic texture after severe plastic deformation (SPD) of the aluminum alloy AA7075, commonly used in the aeronautical and automotive industries, depends on the parameters of the applied deformation process. In this paper, a combination between experimental ECAP processing and [...] Read more.

The evolution of the crystallographic texture after severe plastic deformation (SPD) of the aluminum alloy AA7075, commonly used in the aeronautical and automotive industries, depends on the parameters of the applied deformation process. In this paper, a combination between experimental ECAP processing and numerical simulation using the visco-plastic self-consistent methodology (VPSC) was carried out. The limitations in the homogeneity of the mechanical properties and texture of the parts processed via ECAP can be improved by an adequate choice of the processing route. According to the literature, the most effective route to increase the properties of this material is the Bc route. However, due to the two-fold symmetry along the extrusion axis, the Bc route cannot be used in the components under study. Because of this, it was decided to study C and modified C routes. The simulation results showed the characteristic fibers of the ECAP process measured through X-ray diffraction. The texture analysis shows that the most effective route to obtain a more homogenous shear deformation and therefore reduce the grain size is the Bc route, followed by the modified C route and finally the C route. Full article

(This article belongs to the Special Issue Design, Modeling and Simulation of Metal Forming Processes)

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16 pages, 7065 KiB

Open AccessArticle

Hot Deformation Behavior of Electron-Beam Cold-Hearth Melted Ti-6Al-4V Alloy

by Weiju Jia, Chengliang Mao and Wei Zhou

Metals 2024, 14(12), 1459; https://doi.org/10.3390/met14121459 - 20 Dec 2024

Viewed by 498

Abstract

The deformation behavior and microstructure changes of electron-beam cold-hearth-melted (EBCHM) Ti-6Al-4V alloy were investigated. The stress–strain curves of the alloy were obtained, the constitutive model was established based on the Arrhenius equation, and the hot processing map was drawn. The results showed that [...] Read more.

The deformation behavior and microstructure changes of electron-beam cold-hearth-melted (EBCHM) Ti-6Al-4V alloy were investigated. The stress–strain curves of the alloy were obtained, the constitutive model was established based on the Arrhenius equation, and the hot processing map was drawn. The results showed that the stress of the alloy decreases with increasing temperature and decreasing strain rate. In the β phase field, there are more recrystallized grains when the strain rate is slow, and the recrystallization of the β phase does not have enough time to occur when the strain rate is fast. There are obvious shear bands in the microstructure at the strain rate of 10 s⁻¹. In the α + β field, the morphology and crystallographic orientation of the microstructure changed simultaneously. Globularization is a typical microstructure evolution characteristic. The prismatic slip is easier to activate than basal and pyramidal slips. Moreover, globularization of the lamellar α phase is not synchronously crystallographic and morphological. Full article

(This article belongs to the Special Issue Structure and Mechanical Properties of Titanium Alloys)

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29 pages, 5761 KiB

Open AccessReview

Artificial Intelligence-Driven Innovations in Laser Processing of Metallic Materials

by Serguei P. Murzin

Metals 2024, 14(12), 1458; https://doi.org/10.3390/met14121458 - 20 Dec 2024

Viewed by 1603

Abstract

This article explores the integration of artificial intelligence (AI) and advanced digital technologies into laser processing, highlighting their potential to enhance precision, efficiency, and process control. The study examines the application of digital twins and machine learning (ML) for optimizing laser machining, reducing [...] Read more.

This article explores the integration of artificial intelligence (AI) and advanced digital technologies into laser processing, highlighting their potential to enhance precision, efficiency, and process control. The study examines the application of digital twins and machine learning (ML) for optimizing laser machining, reducing defects, and improving the analysis of laser–material interactions. Emphasis is placed on AI’s role in additive manufacturing and microprocessing, particularly in real-time monitoring, defect prediction, and parameter optimization. Additionally, the article addresses emerging challenges, such as the adaptation of AI models to complex material behaviors and the integration of intelligent systems into existing manufacturing environments. The role of advanced optical technologies, such as free-form optics and diffractive optical elements, is discussed in relation to enhancing laser system adaptability and performance. The article concludes with a discussion on future trends, emphasizing the need for interdisciplinary collaboration to overcome technical and economic complexities while leveraging AI to meet the growing demand for precision and customization in industrial manufacturing. Full article

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13 pages, 5058 KiB

Open AccessArticle

Fabricating and Characterization of MPEA Binder Phase Cemented Carbide and Its Comparison with WC-Co

by Shuailong Zhang, Huichao Cheng, Feng Liu, Kun Li, Cheng Qian and Ji Zhang

Metals 2024, 14(12), 1457; https://doi.org/10.3390/met14121457 - 20 Dec 2024

Viewed by 400

Abstract

The development and research of physically superior multi-principal element alloy (MPEA) binders as cemented carbide binders is a hot topic. In this work, we fabricated a new type of MPEA binder-cemented carbide using the powder metallurgy method and investigated the effects of ball [...] Read more.

The development and research of physically superior multi-principal element alloy (MPEA) binders as cemented carbide binders is a hot topic. In this work, we fabricated a new type of MPEA binder-cemented carbide using the powder metallurgy method and investigated the effects of ball milling parameters and sintering temperature on the microstructure and mechanical properties of the cemented carbide. The results are compared with those of cobalt binder samples under the same conditions. The results show that the ball milling parameters for low-speed long ball milling time are superior to those for high-speed low ball milling time. Compared with the pure cobalt binder, MPEA binder-cemented carbide significantly slows down the growth of WC grains, improves the mechanical properties of cemented carbide, and achieves a combination of TRS of 2741.5 MPa and Rockwell hardness of 91.1 HRA. The multi-principal element alloy (MPEA) binder has the potential to become an excellent substitute for Co. Full article

(This article belongs to the Special Issue Processing, Microstructure and Properties of Cemented Carbide)

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14 pages, 5585 KiB

Open AccessArticle

Improved Surface Properties of Low-Carbon Steel by Chromizing–Titanizing Coating Using Pack Cementation Process

by Ayman Yousef, A. M. Bastaweesy, Ibrahim M. Maafa and Ahmed Abutaleb

Metals 2024, 14(12), 1456; https://doi.org/10.3390/met14121456 - 19 Dec 2024

Viewed by 636

Abstract

This study investigates the application of chromizing and titanizing coatings on low-carbon steel (LCS) via the pack cementation process, utilizing various compositions, temperatures, and durations. The coating was analyzed using standard techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive [...] Read more.

This study investigates the application of chromizing and titanizing coatings on low-carbon steel (LCS) via the pack cementation process, utilizing various compositions, temperatures, and durations. The coating was analyzed using standard techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and Vickers hardness testing, to determine their characteristics. The kinetics of the pack chromizing, titanizing, and chromotitanizing of low-carbon steel exhibited parabolic behavior, with the rate constant with increasing temperature. The formed diffusion layers primarily consisted of Cr, Ti, Cr_1.9Ti, FeTi, Al₂O₃, Cr₂O₃, TiO₂, and Cr_1.36Fe_0.52, in addition to Fe. The microhardness reached its highest value of 900 HV_0.01 Kg_f with 48% FeTi, followed by 790 HV_0.01 Kg_f with 12% FeCr–36% FeTi, 730 HV_0.01 Kg_f with 24% FeCr–24% FeTi, 680 HV_0.01 Kg_f with 36% FeCr–12% FeTi, and 560 HV_0.01 Kg_f with 48% FeCr. The results indicate a significant enhancement in the mechanical properties of low-carbon steel through the coating process. This study confirms that the pack cementation coatings of chromizing, titanizing, and chromotitanizing significantly enhance the surface hardness and mechanical integrity of low-carbon steel. The controlled diffusion process leads to the formation of robust intermetallic layers, and the variation in FeCr and FeTi composition allows for tailored mechanical properties. Additionally, the results suggest that the interplay between Cr and Ti promotes the development of a complex, multilayered microstructure that balances hardness with potential toughness, providing a broad spectrum of industrial applications. This research underscores the versatility of pack cementation as an effective method to engineer advanced coatings, offering a cost-efficient pathway to enhance the performance of low-carbon steel in demanding environments. Full article

(This article belongs to the Topic Alloys and Composites Corrosion and Mechanical Properties)

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19 pages, 18317 KiB

Open AccessArticle

A Study on the Impact Toughness of the Simulated Heat-Affected Zone in Multi-Layer and Multi-Pass Welds of 1000 MPa Grade Steel for Hydroelectric Applications

by Yuwei Li, Yuanbo Li and Jianxiu Chang

Metals 2024, 14(12), 1455; https://doi.org/10.3390/met14121455 - 19 Dec 2024

Viewed by 486

Abstract

The microstructure and impact toughness of a steel material subjected to multi-layer and multi-pass welding with varying secondary peak temperatures were investigated using welding thermal simulation. The detailed microstructures and fracture morphologies were examined by SEM, TEM, and EBSD. When the secondary peak [...] Read more.

The microstructure and impact toughness of a steel material subjected to multi-layer and multi-pass welding with varying secondary peak temperatures were investigated using welding thermal simulation. The detailed microstructures and fracture morphologies were examined by SEM, TEM, and EBSD. When the secondary peak temperature reaches 650 °C, the microstructure resembles that of a primary thermal cycle at 1300 °C, characterized by coarse grains and straight grain boundaries. As the temperature increases to 750 °C, chain-like structures of bulky M/A (martensite/austenite) constituents form at grain boundaries, widening them significantly. At 850 °C, grain boundaries become discontinuous, and large bulky M/A constituents disappear. At 1000 °C, smaller austenitic grains form granular bainite during cooling. However, at 1200 °C, grain coarsening occurs due to the significant increase in peak temperature, accompanied by a lath martensite structure at higher cooling rates. In terms of toughness, the steel exhibits better toughness at 850 °C and 1000 °C, with ductile fracture characteristics. Conversely, at 650 °C, 750 °C, and 1200 °C, the steel shows brittle fracture features. Microscopically, the fracture surfaces at these temperatures exhibit quasi-cleavage fracture characteristics. Notably, chain-like M/A constituents at grain boundaries significantly affect impact toughness and are the primary cause of toughness deterioration in the intercritical coarse-grained heat-affected zone. Full article

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23 pages, 8531 KiB

Open AccessArticle

Investigation of Residual Stress Variation in Sequential Butt Welding and Pocket Material Removal Machining Processes Utilizing Pre-Stress Method: A 3D Simulation Approach

by Isik Cetintav, Yilmaz Can and Nihat Akkus

Metals 2024, 14(12), 1454; https://doi.org/10.3390/met14121454 - 18 Dec 2024

Viewed by 1031

Abstract

This study investigates the residual stresses arising from welding and machining processes, recognizing their adverse implications in manufacturing. Employing experimental analysis and simulation techniques, the research scrutinizes residual stress alterations resulting from sequential butt welding and subsequent machining. Utilizing MSC Marc Mentat software(version [...] Read more.

This study investigates the residual stresses arising from welding and machining processes, recognizing their adverse implications in manufacturing. Employing experimental analysis and simulation techniques, the research scrutinizes residual stress alterations resulting from sequential butt welding and subsequent machining. Utilizing MSC Marc Mentat software(version 2016), three-dimensional models are developed to simulate these processes. The finite element model from welding simulation seamlessly integrates into cutting simulations via the pre-state option. The experimental procedures involve 100 × 100 × 10 mm AISI 304 steel plates subjected to sequential welding and machining, with residual stresses measured at each stage. A comparative analysis between experimental and simulation results elucidates variations in residual stresses induced by sequential processes. The study focuses on examining the initial stress state post-welding and numerically assessing stress modifications due to milling. The results suggest minimal material removal insignificantly affects stress distribution and magnitude at the weld centerline. However, increased material removal leads to noticeable changes in through-thickness transverse stress within the weld zone, contrasting with marginal alterations in through-thickness longitudinal stress. Regions distanced from the weld seam show substantial increases in through-thickness longitudinal stress compared to marginal changes in through-thickness transverse stress. Full article

(This article belongs to the Special Issue Recent Advances in Welding Technology of Alloys and Metals)

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15 pages, 3127 KiB

Open AccessArticle

Research on the Thermal Safety of Ion-Doped Na₃V₂(PO₄)₃ for Sodium-Ion Batteries

by Bo Pei, Xin Qiao, Que Huang, Changcheng Liu, Mengna Shi, Xiaomei Jiang, Feng Li and Li Guo

Metals 2024, 14(12), 1453; https://doi.org/10.3390/met14121453 - 18 Dec 2024

Viewed by 575

Abstract

Na₃V₂ (PO₄)₃ (NVP) is considered to be a promising cathode material for sodium-ion batteries (SIBs). Ion doping can effectively improve its structural deformation, poor conductivity, and electrochemical performance. However, the research on the effect of ion doping [...] Read more.

Na₃V₂ (PO₄)₃ (NVP) is considered to be a promising cathode material for sodium-ion batteries (SIBs). Ion doping can effectively improve its structural deformation, poor conductivity, and electrochemical performance. However, the research on the effect of ion doping on the thermal stability of NVP is still limited. In this paper, Mg/Ti co-doped and Mn/Ti co-doped modified NVP with carbon nanotubes (CNTs) (MgTi@ CNTs and MnTi@CNTs) were prepared, respectively, and X-ray diffraction (XRD) results proved that MgTi@CNTs and MnTi@CNTs have good structural stability and crystallinity. The electrochemical performance indicates that the dual strategy of p-n-type co-doping and CNT coating provides superior sodium storage performance, enhancing both electronic conductivity and ion diffusion. Secondly, based on the safety point of view, the thermal stability of p-n-type ion-doped NVP and its mixed system with electrolyte in a charged state was studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and accelerated calorimeter (ARC). The results show that the optimized MgTi@CNTs and MnTi@CNTs electrodes exhibit excellent thermal stability in the absence of electrolytes, indicating their high intrinsic safety. However, it is worth noting that in the electrode/electrolyte system, p-n-type ion-doped NVP have higher reactivity with the electrolyte, and their comprehensive thermal safety is lower than that of NVP. Therefore, in practical applications, it is necessary to comprehensively consider the thermal stability of the material and the thermal safety of its mixed system with the electrolyte. This paper provides a data basis for the practical application of NVP in SIBs. Full article

(This article belongs to the Special Issue Manufacturing and Characterization of Metallic Electrode Materials (2nd Edition))

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13 pages, 6663 KiB

Open AccessArticle

Effects of HIP on Microstructure and Mechanical Properties of LMD Fe36Mn21Cr1815NiAl10 High-Entropy Alloy

by Gang Wang, Xvteng Lv, Xiangyu Xv and Runbo Zhang

Metals 2024, 14(12), 1452; https://doi.org/10.3390/met14121452 - 18 Dec 2024

Viewed by 505

Abstract

To reduce costs, a cobalt-free FeMnCrNi-based HEA has been proposed. Further investigation into the mechanical properties of the Fe36Mn21Cr18Ni15Al10 alloy is essential to expand its application potential. In this study, a cobalt-free Fe36Mn21Cr18Ni15Al10 HEA was fabricated using LMD, and the effects of HIP [...] Read more.

To reduce costs, a cobalt-free FeMnCrNi-based HEA has been proposed. Further investigation into the mechanical properties of the Fe36Mn21Cr18Ni15Al10 alloy is essential to expand its application potential. In this study, a cobalt-free Fe36Mn21Cr18Ni15Al10 HEA was fabricated using LMD, and the effects of HIP on its microstructure and mechanical properties were investigated. Results indicated that the as-printed specimen exhibited a dual-phase structure consisting of BCC and FCC phases, with the B2 phase dispersed as fine blocks. After HIP treatment, the content of the FCC phase significantly increased, displaying a lamellar distribution between the BCC phases, with secondary block-like B2 phases forming within the BCC matrix. The HIP process enhanced the density of the high-entropy alloy to 98.2%, while the tensile strength at 25 °C increased to 903.9 MPa. Additionally, the post-fracture elongation improved to 17.4%, thereby increasing the potential for industrial applications of HEAs. Full article

(This article belongs to the Special Issue Additive Manufacturing of Intermetallics: Process, Microstructures and Mechanical Properties)

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19 pages, 9955 KiB

Open AccessArticle

Effects of Medium and Flow Rate on the Film-Forming Structures of B10 Cu-Ni Alloys and Their Resistance to Corrosion Caused by Sulfate-Reducing Bacteria

by Bochao Lu, Ning Cui, Yimeng Zhang, Ding Guo, Yanan Wang, Xiaopeng Wang and Jizhou Duan

Metals 2024, 14(12), 1451; https://doi.org/10.3390/met14121451 - 18 Dec 2024

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Abstract

The effects of medium and flow rate on the film-forming structures of B10 Cu-Ni alloys and their resistance to corrosion caused by sulfate-reducing bacteria are investigated in this article. Combined with a predicted cloud map of pipeline corrosion area and a particle motion [...] Read more.

The effects of medium and flow rate on the film-forming structures of B10 Cu-Ni alloys and their resistance to corrosion caused by sulfate-reducing bacteria are investigated in this article. Combined with a predicted cloud map of pipeline corrosion area and a particle motion trajectory map obtained using Computational Fluid Dynamics (CFD), the growth law of alloy passivation films was analyzed and the pitting process of sulfate-reducing bacteria (SRB) on passivation films was revealed. The results show that the film formation effect is best when the stream of water in the film-forming environment is filtered seawater with a flow rate of 0.8 m/s, which consists of a uniform and dense gray-brown passivated film layer with the strongest resistance to SRB corrosion. When the flow rate is 0 m/s, the clay particles in the seawater cover the surface of the passivation film, hindering the contact of oxygen with the substrate and inhibiting the growth of the passivation film. When the stream of water in the film-forming environment is seawater with a flow rate of 3 m/s, the surface of the substrate shows obvious scouring marks, which is favorable for the enrichment of SRB and further accelerates the pitting corrosion of the substrate. Cl⁻ has a significant influence on the formation of passivation films on B10 Cu-Ni alloys. When the filming medium is deionized water, the B10 Cu-Ni alloy does not form a complete passivation film at all flow rates. Full article

(This article belongs to the Section Corrosion and Protection)

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15 pages, 5547 KiB

Open AccessArticle

Hydrometallurgical Method for AgCu Alloy Powder Synthesis and Its Application in Pd(II) Recovery Through Cementation

by Tomasz Michałek, Konrad Wojtaszek, Stanisław Małecki and Marek Wojnicki

Metals 2024, 14(12), 1450; https://doi.org/10.3390/met14121450 - 18 Dec 2024

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Abstract

This study investigates the synthesis, characterization, and potential applications of silver–copper (AgCu) alloy powders produced from co-precipitated carbonates. The Cu/Ag carbonate samples were analyzed using EDXRF, TGA-DSC, XRD, SEM, and electrical conductivity tests to examine their composition, thermal behavior, structure, and morphology. The [...] Read more.

This study investigates the synthesis, characterization, and potential applications of silver–copper (AgCu) alloy powders produced from co-precipitated carbonates. The Cu/Ag carbonate samples were analyzed using EDXRF, TGA-DSC, XRD, SEM, and electrical conductivity tests to examine their composition, thermal behavior, structure, and morphology. The results showed slight deviations from the theoretical Cu/Ag ratios in the carbonates, attributed to equilibrium effects during precipitation. Thermal analysis indicated that the reduction process of carbonates with hydrogen was completed at 300 °C, while alloy formation was confirmed by endothermic peaks around 780 °C. XRD and SEM analyses revealed that AgCu alloys formed a solid solution, with smaller crystallite sizes observed at higher Cu contents. Electrical conductivity tests demonstrated that while pure Ag and Cu powders exhibited conductivity increases with compaction, the AgCu alloy showed stable conductivity without a significant decrease. In Pd(II) cementation experiments, AgCu alloys demonstrated higher efficiency in Pd(II) recovery than pure Ag and Cu. These findings suggest that AgCu alloys, particularly with a balanced composition, may offer improved performance for metal recovery applications, providing a promising approach for industrial cementation processes. Full article

(This article belongs to the Special Issue Current Trends in Non-Ferrous Metals Extraction, Separation, and Refining)

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10 pages, 2791 KiB

Open AccessArticle

Structural Transformations in Duplex Stainless Steel CF8 Under Intensive Cold Plastic Deformation

by Mikhail Vereshchak, Irina Manakova, Gaukhar Yeshmanova and Zhandos Tleubergenov

Metals 2024, 14(12), 1449; https://doi.org/10.3390/met14121449 - 17 Dec 2024

Viewed by 482

Abstract

The austenitic–martensitic transformation in austenitic–ferritic duplex stainless steel CF8 subjected to cold plastic deformation with a deformation degree ε = 10–95% is studied here using transmission Mössbauer spectroscopy (MS), conversion electron Mössbauer spectroscopy (CEMS), and X-ray diffraction (XRD) methods. It is assumed that [...] Read more.

The austenitic–martensitic transformation in austenitic–ferritic duplex stainless steel CF8 subjected to cold plastic deformation with a deformation degree ε = 10–95% is studied here using transmission Mössbauer spectroscopy (MS), conversion electron Mössbauer spectroscopy (CEMS), and X-ray diffraction (XRD) methods. It is assumed that the α′-martensite phase appeared at ε > 10%. The CEMS results showed that the formation of α′-martensite occurred most intensively in the near-surface layers of the steel, distributing in depth with the growth of the deformation degree. The volume fraction of the α′-martensite was determined based on the results of calculations carried out via the MS and XRD methods, and a good correlation was observed. A modified Olson–Cohen model was proposed to determine the dependence of the amount of α′-martensite on the deformation degree ε. The coefficients included in the Olson–Cohen expression were found. Full article

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31 pages, 13595 KiB

Open AccessReview

Resistance Element Welding (REW) of Steels with Non-Ferrous Materials: Potentials, Challenges, and Properties

by Mohammad Abankar, Manuela De Maddis, Valentino Razza and Pasquale Russo Spena

Metals 2024, 14(12), 1448; https://doi.org/10.3390/met14121448 - 17 Dec 2024

Viewed by 767

Abstract

Performance and functionality are two key factors in designing advanced components. One promising approach in manufacturing design is the fabrication of multi-material structures by joining dissimilar materials. Steels, known for their outstanding properties and cost-effective production, are widely used across several industries. However, [...] Read more.

Performance and functionality are two key factors in designing advanced components. One promising approach in manufacturing design is the fabrication of multi-material structures by joining dissimilar materials. Steels, known for their outstanding properties and cost-effective production, are widely used across several industries. However, their high density presents challenges when designing lightweight components. A solution lies in combining steels with lightweight, non-ferrous alloys to develop cost-effective multi-material parts. However, joining different materials is generally complex due to their different properties, making it sometimes challenging or even unfeasible. Resistance element welding (REW) offers a high-performance alternative to traditional methods, such as resistance spot welding, with a high potential in mass production industries like automotive manufacturing. This article comprehensively reviews the latest research on REW for dissimilar joining of steels and non-ferrous alloys. It focuses on the microstructural and mechanical properties of joints, innovations in the REW process, the influence of process parameters on joint quality, as well as simulation and numerical studies. In addition, REW is compared with traditional joining methods. Full article

(This article belongs to the Special Issue Welding Metallurgy and Processes of Dissimilar Materials)

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16 pages, 11126 KiB

Open AccessArticle

Fracture and Fatigue Crack Growth Behaviour of A516 Gr 60 Steel Welded Joints

by Nikola Kostić, Ivica Čamagić, Aleksandar Sedmak, Milivoje Jovanović, Zijah Burzić, Tamara Golubović, Simon Sedmak and Igor Martić

Metals 2024, 14(12), 1447; https://doi.org/10.3390/met14121447 - 17 Dec 2024

Viewed by 578

Abstract

The facture and fatigue behaviour of welded joints made of A516 Gr 60 was analysed, bearing in mind their susceptibility to cracking, especially in the case of components which had been in service for a long time period. With respect to fracture, the [...] Read more.

The facture and fatigue behaviour of welded joints made of A516 Gr 60 was analysed, bearing in mind their susceptibility to cracking, especially in the case of components which had been in service for a long time period. With respect to fracture, the fracture toughness was determined for all three zones of a welded joint, the base metal (BM), heat-affected zone (HAZ) and weld metal (WM), by applying a standard procedure to evaluate K_Ic via based on J_Ic values (ASTM E1820). With respect to fatigue, the fatigue crack growth rates were determined according to the Paris law by the standard procedure (ASTM E647) to evaluate the behaviour of different welded joint zones under amplitude loading. The results obtained for A516 Gr. 60 structural steel showed why it is widely used in the case of static loads, since the minimum value of fracture toughness (185 MPa√m) provides relatively large critical crack lengths, whereas its behaviour under amplitude loading indicated a need for further improvement in WM and HAZ, since the crack growth rate reached values as high as 4.58 × 10⁻⁴ mm/cycle. In addition, risk-based analysis was applied to assess the structural integrity of a pressure vessel, including comparison with the high-strength low-alloy (HSLA) steel NIOVAL 50, proving once again its superior behaviour under static loading. Full article

(This article belongs to the Special Issue Fracture Mechanics and Failure Analysis of Metallic Materials)

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21 pages, 6488 KiB

Open AccessArticle

X-Ray Diffraction Line Broadening of Irradiated Zr-2.5Nb Alloys

by Malcolm Griffiths

Metals 2024, 14(12), 1446; https://doi.org/10.3390/met14121446 - 17 Dec 2024

Viewed by 433

Abstract

The evolution of the mechanical properties of Zr-2.5Nb pressure tubing during irradiation is dependent on dislocation loop densities that are represented by the broadening of X-ray diffraction lines. Empirical models for the integral breadth of the diffraction peaks as a function of operating [...] Read more.

The evolution of the mechanical properties of Zr-2.5Nb pressure tubing during irradiation is dependent on dislocation loop densities that are represented by the broadening of X-ray diffraction lines. Empirical models for the integral breadth of the diffraction peaks as a function of operating conditions have been developed to predict the mechanical properties of CANDU reactor pressure tubes as a function of fast neutron flux, time and temperature. Apart from predicting mechanical property changes based on integral breadth measurements, a new model has been developed to retrospectively deduce abnormal operating temperatures of ex-service pressure from the measured line broadening. The application of integral breadth measurements to assess mechanical properties and temperature variations in pressure tubes is described and discussed in terms of the implications for pressure tube integrity. Full article

(This article belongs to the Special Issue Manufacture, Properties and Applications of Advanced Nuclear Alloys)

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13 pages, 6566 KiB

Open AccessArticle

Optimization of Strength and Plasticity in Layered Aluminum Composites Through High-Pressure Torsion Treatment

by Alexey Evstifeev, Aydar Mavlyutov, Artem Voropaev and Darya Volosevich

Metals 2024, 14(12), 1445; https://doi.org/10.3390/met14121445 - 17 Dec 2024

Viewed by 531

Abstract

The development of high-strength aluminum alloys with improved ductility is a crucial challenge for modern materials science, as high strength and ductility tend to be mutually exclusive properties. In this work, the composite material was fabricated using wire arc additives manufactured from AA1050 [...] Read more.

The development of high-strength aluminum alloys with improved ductility is a crucial challenge for modern materials science, as high strength and ductility tend to be mutually exclusive properties. In this work, the composite material was fabricated using wire arc additives manufactured from AA1050 (commercially pure aluminum) and AA5056 (an Al–Mg system alloy) aluminum alloys. It was demonstrated that the addition of a lower-strength material into a high-strength matrix enhances the potential for deformation localization and results in an increased plasticity of the composite material. A further strengthening of the composite material was achieved through its deformation by a high-pressure torsion (HPT) technique. The mechanical properties of the material were thoroughly investigated before and after the HPT treatment. Static strength and plasticity were analyzed as a function of the deformation degree. Microstructural analysis was performed using scanning electron microscopy and X-ray diffraction. The optimal deformation route, providing the best combination of mechanical properties, was experimentally identified, along with key microstructural parameters of the formed composite with a bimodal grain structure. A deformation level corresponding to 36% of shear stress provides a yield stress of up to 570 MPa, an ultimate tensile strength of up to 664 MPa, and a relative elongation to failure of up to 7%. As a result of the deformation treatment, characteristic substructures with dimensions of ~250 nm and >1000 nm are formed, with a volume ratio of approximately 80/20. Full article

(This article belongs to the Section Additive Manufacturing)

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14 pages, 13708 KiB

Open AccessArticle

The Corrosion Behavior of Carbon Steel Materials Used at Nuclear Power Plants During Deactivation and Decommissioning Processes

by Wen-Feng Lu, Tai-Cheng Chen, Kun-Chao Tsai and Tung-Yuan Yung

Metals 2024, 14(12), 1444; https://doi.org/10.3390/met14121444 - 17 Dec 2024

Viewed by 573

Abstract

This study is focused on the corrosion behavior of carbon steel A106 B in a static water environment, which simulated the decommissioning transition phase of BWR power plants. When the autoclave was filled with stagnant water, the corrosion rates of carbon steel pipe [...] Read more.

This study is focused on the corrosion behavior of carbon steel A106 B in a static water environment, which simulated the decommissioning transition phase of BWR power plants. When the autoclave was filled with stagnant water, the corrosion rates of carbon steel pipe for the cold-drawn and hot-rolled samples were 23 μm/year and 19 μm/year, respectively. When the autoclave was not completely filled with water, leaving the samples fully submerged, the corrosion rate for the hot-rolled sample increased to 88 μm/year. In an autoclave with periodic water flow, the corrosion rate for the cold-drawn sample decreased to 11 μm/year. When the autoclave was not completely filled with water, the sample positioned at the air–water interface exhibited the highest corrosion rate of approximately 102 μm/year. These results indicate that the influence of ion concentration on the corrosion rate outweighed that of dissolved oxygen. Sufficient oxygen concentration facilitated the formation of FeOOH or Fe₂O₃, while an oxygen-deficient environment favored the formation of Fe₃O₄. Full article

(This article belongs to the Special Issue Corrosion Behavior of Carbon Steels in Natural and Industrial Environments—2nd Edition)

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22 pages, 14009 KiB

Open AccessArticle

Research on the Weldability and Service Performance of 7075 Aluminum Alloy Welding Wire Prepared by Spray Forming–Extrusion–Drawing

by Chunkai Zhou, Xiaoping Li and Gao Hua

Metals 2024, 14(12), 1443; https://doi.org/10.3390/met14121443 - 17 Dec 2024

Viewed by 668

Abstract

A large number of MIG welding tests were carried out on a 3 mm thick 7075 aluminum alloy plate prepared by the self-developed jet forming–extrusion–drawing process of 7075 high-strength aluminum alloy welding wire, and the welding process of the welding wire and the [...] Read more.

A large number of MIG welding tests were carried out on a 3 mm thick 7075 aluminum alloy plate prepared by the self-developed jet forming–extrusion–drawing process of 7075 high-strength aluminum alloy welding wire, and the welding process of the welding wire and the change in the performance of the welded joint after T6 heat treatment were studied. The results show that the self-developed wire has a good forming joint and a wide welding process window: the welding speed is 5–7 mm/s, and the welding current is 100–150 A. The main precipitated phases in the joint were η(MgZn₂), S(CuMgAl₂), Mg₂Si, and Al₁₃Fe₄, which were continuously distributed at the grain boundaries in the form of coarse networks or long strips, which was an important reason for the weak performance of the joints. After the heat treatment of T6, the precipitated phase in the joint was greatly reduced, the element segregation phenomenon was improved, and the residual precipitated phase was mainly Al₁₃Fe₄ and a small amount of insoluble phase Fe and Si, and the recrystallization size of the heat-affected zone was refined. Through heat treatment, the average microhardness of the joint was increased from 110 HV to 150.24 HV, and the tensile strength was increased from 326 MPa to 536 MPa, reaching 97.5% of the strength of the base metal, indicating that the softening phenomenon was significantly improved after heat treatment, and the joint had excellent performance. Full article

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19 pages, 14782 KiB

Open AccessArticle

Innovative Solid-State Recycling of Aluminum Alloy AA6063 Chips Through Direct Hot Rolling Process

by Mauro Carta, Noomane Ben Khalifa, Pasquale Buonadonna, Rayane El Mohtadi, Filippo Bertolino and Mohamad El Mehtedi

Metals 2024, 14(12), 1442; https://doi.org/10.3390/met14121442 - 17 Dec 2024

Viewed by 3126

Abstract

In this paper, the feasibility of an innovative solid-state recycling process for aluminum alloy AA6063 chips through direct rolling is studied, with the aim of offering an environmentally sustainable alternative to conventional recycling processes. Aluminum chips, produced by milling an AA6063 billet without [...] Read more.

In this paper, the feasibility of an innovative solid-state recycling process for aluminum alloy AA6063 chips through direct rolling is studied, with the aim of offering an environmentally sustainable alternative to conventional recycling processes. Aluminum chips, produced by milling an AA6063 billet without the use of lubricants, were first compacted using a hydraulic press with a 200 kN load and subsequently heat-treated at 570 °C for 6 h. The compacted chips were directly hot-rolled through several successive passes at 490 °C. The bulk material underwent the same rolling schedule to allow comparison of the samples and assess the process, in terms of mechanical properties and microstructure. All the rolled samples were tested by tensile and microhardness tests, whereas the microstructure was observed by an optical microscope and the EBSD-SEM technique. The fracture surface of all tested samples was analyzed by SEM. Recycled samples exhibited good mechanical properties, comparable to those of the bulk material. In particular, the bulk material showed an ultimate tensile strength of 218 MPa, in contrast to 177 MPa for the recycled chips, and comparable elongation at break. This study demonstrates that direct rolling of compacted aluminum chips is both technically feasible and has environmental benefits, offering a promising approach for sustainable aluminum recycling in industrial applications within a circular economy framework. Full article

(This article belongs to the Special Issue Sustainability Approaches in the Recycling of Light Alloys)

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18 pages, 3357 KiB

Open AccessArticle

Deep Eutectic Solvent (TOPO/D2EHPA/Menthol) for Extracting Metals from Synthetic Hydrochloric Acid Leachates of NMC-LTO Batteries

by Arina V. Kozhevnikova, Nikita A. Milevskii, Dmitriy V. Lobovich, Yulia A. Zakhodyaeva and Andrey A. Voshkin

Metals 2024, 14(12), 1441; https://doi.org/10.3390/met14121441 - 16 Dec 2024

Viewed by 680

Abstract

The recycling of lithium-ion batteries is increasingly important for both resource recovery and environmental protection. However, the complex composition of cathode and anode materials in these batteries makes the efficient separation of metal mixtures challenging. Hydrometallurgical methods, particularly liquid extraction, provide an effective [...] Read more.

The recycling of lithium-ion batteries is increasingly important for both resource recovery and environmental protection. However, the complex composition of cathode and anode materials in these batteries makes the efficient separation of metal mixtures challenging. Hydrometallurgical methods, particularly liquid extraction, provide an effective means of separating metal ions, though they require periodic updates to their extraction systems. This study introduces a hydrophobic deep eutectic solvent composed of trioctylphosphine oxide, di(2-ethylhexyl)phosphoric acid, and menthol, which is effective for separating Ti(IV), Co(II), Mn(II), Ni(II), and Li⁺ ions from hydrochloric acid leachates of NMC (LiNi_xMn_yCo_1−x−yO₂) batteries with LTO (Li₄Ti₅O₁₂) anodes. By optimising the molar composition of the trioctylphosphine oxide/di(2-ethylhexyl)phosphoric acid/menthol mixture to a 4:1:5 ratio, high extraction efficiency was achieved. The solvent demonstrated stability over 10 cycles, and conditions for its regeneration were successfully established. At room temperature, the DES exhibited a density of 0.89 g/mL and a viscosity of 56 mPa·s, which are suitable for laboratory-scale extraction processes. Experimental results from a laboratory setup with mixer-settlers confirmed the efficiency of separating Ti(IV) and Co(II) ions in the context of their extraction kinetics. Full article

(This article belongs to the Section Extractive Metallurgy)

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15 pages, 5750 KiB

Open AccessArticle

A Contribution to the Study of the Integrity Surface of the IC10 Ni3Al-Based Alloy After Creep-Feed Grinding with a Focus on High-Temperature Fatigue Life

by Shuaiqi Zhang, Lijie Hu, Zhenyu Yang, Shuxin Niu, Huzi Bao, Qichao Jin, Duoji Renqing and Ruisong Jiang

Metals 2024, 14(12), 1440; https://doi.org/10.3390/met14121440 - 16 Dec 2024

Viewed by 588

Abstract

The IC10 directionally solidified superalloy is a nickel-based alloy with high temperature resistance, and its surface integrity has a significant impact on the fatigue life of critical hot-end components in aerospace engines. This paper investigates the influence of creep-feed grinding surface integrity (surface [...] Read more.

The IC10 directionally solidified superalloy is a nickel-based alloy with high temperature resistance, and its surface integrity has a significant impact on the fatigue life of critical hot-end components in aerospace engines. This paper investigates the influence of creep-feed grinding surface integrity (surface roughness and surface hardness) on the high-temperature fatigue life of IC10 directionally solidified superalloy. High-temperature fatigue life tests were conducted on IC10 directionally solidified superalloy, and a method for evaluating the high-temperature fatigue life of the IC10 directionally solidified superalloy using surface integrity is proposed. The results indicate that as the surface roughness Ra increases from 0.60 μm to 2.15 μm, the maximum valley depth Rv of the grinding surface profile and the stress concentration factor increase, leading to more scratches and wider grooves. The fatigue fracture of IC10 consists of a fatigue source zone, a fatigue propagation zone, and an instantaneous fracture zone. With increasing surface roughness, the number of fatigue sources also increases, and the stress concentration on the grinding surface intensifies. Under the action of multiple fatigue propagation sources, the sample structure is more likely to reach a critical value and lose stability, leading to fracture and thus reducing the high-temperature fatigue life. When the surface hardness increases from 387.11 HV to 393.60 HV, the high-temperature fatigue life of IC10 improves by 68.13%; when the surface hardness increases from 401.62 HV to 418.13 HV, the high-temperature fatigue life of IC10 decreases by 73.12%. The surface integrity of the IC10 directionally solidified superalloy has a notable impact on its high-temperature fatigue life. Full article

(This article belongs to the Special Issue Metal Plastic Deformation and Forming)

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Metals, Volume 14, Issue 12 (December 2024) – 157 articles

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