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Metals, Volume 14, Issue 11 (November 2024) – 114 articles

Cover Story (view full-size image): Structural and textural evolution in Electron Beam Powder Bed Fusion (EB-PBF) is governed by the complex interplay of thermo-kinetic and thermo-mechanical phenomena during melting and solidification. This study from the Center for Agile and Adaptive Additive Manufacturing at the University of North Texas explores how stochastic spot melting (FreeMelt®) and preheat temperature affect the evolution of microstructure and texture of SS316L. A 3D thermo-kinetic/mechanical model revealed compressive stress-driven <110> texture formation, preferred {110}<001> and {110}<111> orientations influenced by solidification kinetics and spatial spot arrangement and triangular-shaped grains orthogonal to build direction. This work provides fundamental insights for optimizing EB-PBF texture and microstructure. View this paper
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11 pages, 3468 KiB  
Article
Large-Scale Atomistic Simulation of Sintering Process and Mechanical Properties of Al Matrix Composite with Different Reinforcements
by Yongchao Zhu, Can Sui, Na Li, Lijuan Sun and Songtao Li
Metals 2024, 14(11), 1312; https://doi.org/10.3390/met14111312 - 20 Nov 2024
Viewed by 460
Abstract
Through molecular dynamics methods, composite models built with a large scale were employed to investigate the effects of different reinforcements, which were different from those used in most of the similar studies, where only a graphene nanosheet (GNS) or a rigid spherical particle [...] Read more.
Through molecular dynamics methods, composite models built with a large scale were employed to investigate the effects of different reinforcements, which were different from those used in most of the similar studies, where only a graphene nanosheet (GNS) or a rigid spherical particle was embedded in a metal matrix. Here, 27 GNSs or diamond particles were placed in the empty spaces between Al particles with random directions. Then, Al matrix composites were prepared by modeling a sintering process. Structural analysis and tensile modeling were carried out on the sintered composites. The results indicate that the density of the Al–graphene composite was higher and increased with growth in the size of the reinforcements, although the Al–graphene system required more heating time to achieve densification. Bigger GNSs were likely to increase the pore volume of the composite. Meanwhile, larger GNSs were also more beneficial for grain refinement, leading to growth in the ratio of Al atoms at grain boundaries. The greater impact of GNSs on the inner structure was not just derived from their high specific surface area, and this impact was enlarged if drawn as a function of the weight fraction rather than the surface area. However, tensile processes revealed that two-dimensional (2D) materials seemed to have no clear impact on the direct strengthening effect, and anisotropy could not be observed in the large-scale models. The biggest GNSs even led to reductions in both the tensile strength and ductility of the Al–graphene composite, which coincided with some experimental reports. The evolution of the inner structures indicated that GNSs have the same role as diamond particles in dislocation accumulation and crack propagation. The major advantage of GNSs is their ability to improve the densification and grain refinement of the metal matrix composite (MMC). Full article
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18 pages, 5584 KiB  
Article
Physical and Mechanical Properties of Ti-Zr-Nb Alloys for Medical Use
by Konstantin V. Sergienko, Sergei V. Konushkin, Mikhail A. Kaplan, Artem D. Gorbenko, Yucheng Guo, Elena O. Nasakina, Maria A. Sudarchikova, Tatiana M. Sevostyanova, Yaroslava A. Morozova, Lyudmila A. Shatova, Sofia A. Mikhlik, Mikhail A. Sevostyanov and Alexey G. Kolmakov
Metals 2024, 14(11), 1311; https://doi.org/10.3390/met14111311 - 20 Nov 2024
Viewed by 476
Abstract
The work described in this article is aimed at investigating the properties of a group of Ti-Zr-Nb alloys. In modern orthopedics and traumatology, the use of materials for bone implants with a minimum modulus of elasticity is becoming increasingly important. This is due [...] Read more.
The work described in this article is aimed at investigating the properties of a group of Ti-Zr-Nb alloys. In modern orthopedics and traumatology, the use of materials for bone implants with a minimum modulus of elasticity is becoming increasingly important. This is due to a number of advantages that allow for better integration of the implants with the bone tissue, including the reduction in the detrimental effect of the load-shielding effect, a better load distribution, and stress distribution, which allows for increasing the life of the implant. It is known that the lowest modulus of elasticity in titanium alloys at normal temperature is achieved by the phase composition consisting of metastable β-phase. It is possible to achieve the desired structure by a combination of alloy composition selection and heat treatment. Quenching of titanium alloys allows for the high-temperature β-phase to be fixed. This paper provides justification of the choice of compositions of the studied alloys by calculation methods. The structure of alloys after melting in a vacuum electric arc furnace in an argon environment was studied. The ingots obtained had a dendritic structure. Homogenizing annealing in a vacuum furnace at 1000 °C for 4 h was used to equalize the composition. The structure of the alloyed sheets after hot rolling and hot rolling and quenching was investigated. The microstructure of the plates in both variants had uniform grains of polyhedral shape. X-ray phase analysis of the plates showed that the content of metastable β-phase was 100% before and after quenching. Microhardness testing of the plates showed no significant effect of quenching. The result of the mechanical properties study showed an increase in the plasticity of the material after quenching, with the tensile plots of the samples after quenching reflecting the area where the reverse phase transition of β’<-> α’’ occurs. Mechanical studies by cyclic loading showed the presence of a superelasticity effect. The Young’s modulus study gave a result of 51 GPa for one of the compositions studied. The combination of properties of the materials under investigation has the potential for promising use as a basis for bone implants. Full article
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10 pages, 8729 KiB  
Article
Effect of Extrusion Ratio on Microstructure and Properties of Al-1.5Fe-0.4Cr Alloy Obtained by Continuous Rheo-Extrusion
by Yunhe Ning, Li Yang, Minqiang Gao and Renguo Guan
Metals 2024, 14(11), 1310; https://doi.org/10.3390/met14111310 - 20 Nov 2024
Viewed by 421
Abstract
Due to the shortage of primary Al resources and significant consumption of Al resources, recycled Al has become a focus of attention. In the process of recycling Al, the Fe element is the most hazardous impurity element, and the coarse Fe-containing phases lead [...] Read more.
Due to the shortage of primary Al resources and significant consumption of Al resources, recycled Al has become a focus of attention. In the process of recycling Al, the Fe element is the most hazardous impurity element, and the coarse Fe-containing phases lead to a reduction in the mechanical properties of recycled Al. In this work, an Al alloy with 1.5 wt% Fe and 0.4 wt% Cr was viewed as a recycled Al, approximately. The continuous rheo-extrusion technique was used to refine the Fe-containing phases in the Al-1.5Fe-0.4Cr alloy, improving the mechanical properties of the alloy. The effect of the extrusion ratio on the microstructure and properties of the continuous rheo-extrusion was investigated. The results showed that, when the extrusion ratio was changed from 4 to 5, the percentage of low-angle grain boundaries in the alloy increased from 45.5% to 53.1%, the average orientation angle reduced from 23.9° to 23.3°, and the grain size decreased from 4.3 ± 0.2 μm to 2.6 ± 0.1 μm. As a result, the ultimate tensile strength, yield strength and elongation of the alloy, with an extrusion ratio of 5, were 161.5 ± 2.8 MPa, 112.3 MPa ± 2.6, and 36.9% ± 1.6%, respectively. Grain refinement and Fe-containing phase refinement were responsible for the improvement in the mechanical properties of the alloy. Full article
(This article belongs to the Special Issue Advances in Lightweight Material Forming Technology)
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21 pages, 13020 KiB  
Article
Comparison of Strengthening Mechanism of the Nb, V, and Nb-V Micro-Alloyed High-Strength Bolt Steels Investigated by Microstructural Evolution and Strength Modeling
by Hui Wen, Qian Wang, Yueyuan Dou, Qiang Wang, Xiaochun Xu and Qingfeng Wang
Metals 2024, 14(11), 1309; https://doi.org/10.3390/met14111309 - 20 Nov 2024
Viewed by 435
Abstract
The strengthening mechanism of Nb, V, and Nb-V micro-alloyed high-strength bolt steels was investigated and compared using microstructural evolution and strength modeling. Optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to characterize the microstructure [...] Read more.
The strengthening mechanism of Nb, V, and Nb-V micro-alloyed high-strength bolt steels was investigated and compared using microstructural evolution and strength modeling. Optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to characterize the microstructure and precipitations. The results show that Nb-V composite micro-alloyed steel possessed a higher yield strength compared with Nb or V micro-alloyed steel when quenched at 870 °C and tempered at 450–650 °C. Furthermore, the strength increment of Nb-V micro-alloyed steel with respect to Nb or V micro-alloyed steel reached the maximum at a tempering temperature of 600 °C, and precipitation strengthening and dislocation strengthening presented higher strength contributions in Nb-V micro-alloyed steel than in Nb micro-alloyed steel and V micro-alloyed steel owing to the higher volume fraction and finer precipitate size. When V was added in combination with Nb in steel, the number of Nb-rich carbonitrides increased, which resulted in a higher volume fraction of the effective pinning particles-Nb-rich (Ti,Nb,V)(C,N) with diameters smaller than 50 nm and led to an enhanced refinement of the prior austenite grain. In addition, Nb could reduce the consumption of V during quenching, allowing more V to be solid-solved in the matrix after quenching, thereby further enhancing the precipitation strengthening effect of V during tempering. Full article
(This article belongs to the Special Issue Microalloying in Ferrous and Non-ferrous Alloys)
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20 pages, 4740 KiB  
Article
Extrusion-Based Additive Manufacturing of WC-10Co Cemented Carbide Produced with Bimodal Ultrafine/Micron WC Particles
by Mikhail Sergeevich Lebedev, Vladimir Vasilevich Promakhov, Lyudmila Yurievna Ivanova, Natalya Valentinovna Svarovskaya, Marina Ivanovna Kozhukhova and Marat Izralievich Lerner
Metals 2024, 14(11), 1308; https://doi.org/10.3390/met14111308 - 20 Nov 2024
Viewed by 494
Abstract
This article researches the effect of ultrafine (submicron) tungsten carbide powder addition on the microstructure and mechanical properties of WC-10Co cemented carbide produced by the extrusion of a highly filled polymer. This addition aims to develop a material with a good combination of [...] Read more.
This article researches the effect of ultrafine (submicron) tungsten carbide powder addition on the microstructure and mechanical properties of WC-10Co cemented carbide produced by the extrusion of a highly filled polymer. This addition aims to develop a material with a good combination of toughness, hardness, and yield strength. The results demonstrate that increasing the ratio between ultrafine and micron WC particles from 0/100 to 45/55 in the initial powder results in successive decreases in average grain size from 2.61 µm to 1.75 µm. When 45% of ultrafine powder is introduced into the mixture, a high number of fine tungsten carbide grains is produced. This promotes inter-grain contact and reduces the free path of the binder phase, which results in a more rigid structure and in the material becoming more brittle. The best mechanical characteristics are achieved in WC-10Co cemented carbide with 15% content of ultrafine powder in the total weight of WC. Here, a microstructure with a bimodal distribution of tungsten carbide grains in a virtually non-intermittent cobalt phase was formed. This allowed us to achieve a compressive strength of 2449 MPa at the deformation of 6.69%, while the modulus of elasticity was 38.8 GPa. The results indicate a good combination of strength and ductility properties in the developed cemented carbide. Full article
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14 pages, 4618 KiB  
Article
Microstructural and Morphological Properties of AlNiCo and CoNi Alloys: An In-Depth Study Based on Low-Energy Mechanical Alloying
by Gilberto Cruz Nieto, Jesús Noé Rivera Olvera, Sebastián Díaz de la Torre, Vicente Garibay Febles, Jesús Palacios Gómez, Leonardo Gonzalez Reyes and Lucía Graciela Diaz Barriga Arceo
Metals 2024, 14(11), 1307; https://doi.org/10.3390/met14111307 - 20 Nov 2024
Viewed by 562
Abstract
This study focused on synthesizing AlNiCo and CoNi materials using a low-energy milling process. The aim was to explore the formation of low-energy phases in both systems, contrasting with the typical research on phases formed under high-energy conditions. In the Co-20 wt% Ni [...] Read more.
This study focused on synthesizing AlNiCo and CoNi materials using a low-energy milling process. The aim was to explore the formation of low-energy phases in both systems, contrasting with the typical research on phases formed under high-energy conditions. In the Co-20 wt% Ni system, the phases Co0.75Ni0.25 and Ni were identified, as well as the FCC cubic phase of CoNi, using X-ray diffraction (XRD) with a molybdenum radiation source. The observed behavior aligned closely with the miscibility curve in the equilibrium phase diagram, which included a region of alloys with varying structures and similar compositions. A notable feature was the presence of a predominantly dispersed hexagonal Ni zone, consisting of nanoparticles. Transmission electron microscopy (TEM) was employed to observe the FCC CoNi phase, which displayed a specific arrangement. AlNiCo and CoNi alloys were successfully synthesized through mechanical alloying, incorporating equilibrium and non-equilibrium phases. Full article
(This article belongs to the Special Issue Powder Metallurgy of Metallic Materials)
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15 pages, 25026 KiB  
Article
Reduction Behaviors of Silicon–Ferrite from Calcium and Aluminum in a Hydrogen-Rich Blast Furnace
by Keshuai Du, Changqing Hu, Xuefeng Shi and Guangqing Yang
Metals 2024, 14(11), 1306; https://doi.org/10.3390/met14111306 - 19 Nov 2024
Viewed by 460
Abstract
Silicon–ferrite from calcium and aluminum (SFCA) is one of the primary binding phases in sinter. To better investigate the reduction process of SFCA under hydrogen-rich conditions in a blast furnace, isothermal reduction experiments were designed using three different hydrogen volume fractions (6%, 10%, [...] Read more.
Silicon–ferrite from calcium and aluminum (SFCA) is one of the primary binding phases in sinter. To better investigate the reduction process of SFCA under hydrogen-rich conditions in a blast furnace, isothermal reduction experiments were designed using three different hydrogen volume fractions (6%, 10%, and 14%) at temperatures within the blast furnace’s lump zone range (1073 K, 1173 K, and 1273 K). The experimental results revealed that the reduction of SFCA proceeds in two stages: in the first stage, SFCA is initially reduced to Fe3O4; in the second stage, Fe3O4 is further reduced to FeO, with the equilibrium phases being FeO, Ca2Al2SiO7, and Ca2SiO4. The fastest reduction rate was observed at 1273 K. When the hydrogen volume fraction was 6% and the temperatures were 1073 K, 1173 K, and 1273 K, the reaction mechanism followed the 3D diffusion model (G-B), with an apparent activation energy of 32.087 kJ·mol1 and a pre-exponential factor of 0.1419. In comparison, at hydrogen volume fractions of 10% and 14%, the reaction mechanism shifted to the Shrinking core model (n = 3). The findings of this study can provide guidance for actual production and optimization of blast furnace parameters aimed at achieving low-carbon emissions in the steel-making process. Full article
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15 pages, 38734 KiB  
Article
Material Flow and Microstructural Evolution in Friction Stir Welding of LAZ931 Duplex Mg-Li Alloys
by Shiquan Cui, Wenguan Cao, Qi Zhang, Liguo Wang, Yufeng Sun and Shaokang Guan
Metals 2024, 14(11), 1305; https://doi.org/10.3390/met14111305 - 19 Nov 2024
Viewed by 453
Abstract
The material flow behavior during friction stir welding (FSW) plays a critical role in the quality of final joints. In this study, the FSW of LAZ931 duplex Mg alloy was carried out at a rotation speed of 800 rpm and welding speeds of [...] Read more.
The material flow behavior during friction stir welding (FSW) plays a critical role in the quality of final joints. In this study, the FSW of LAZ931 duplex Mg alloy was carried out at a rotation speed of 800 rpm and welding speeds of 50, 100, and 200 mm/min, respectively. A thin pure Mg strip inserted at the interface between the two Mg-Li alloy plates was used as a marker to study the flow behavior of the materials in the FSW process. Sound welds with no defects were obtained for all three welding speeds. The microstructural evaluations along the marker on the horizontal cross-section around the keyhole of the welds were characterized. As the welding speed increased, the marker came closer to the keyhole, indicating the decreased extent of the plastic deformation of the material. In the shoulder-affected zone (SAZ), the thickness of the marker reduced gradually in the accelerating stage and finally accumulated together in the decelerating stage. However, in the pin-affected zone (PAZ), the thickness of the marker reduced sharply in the accelerating stage and then became dispersed in the decelerating stage, and the degree of dispersion decreased as the weld speed increased. As a result, an elongated grain structure was formed in the SAZ, while two equiaxial grain structures were formed in the PAZ. The material on the advancing side was refined by the pin and deposited in the weld to form a fine equiaxial grain structure due to the high strain rate. In contrast, the material on the retreating side was pushed by the pin and thus directly deposited in the weld to form a coarse equiaxial grain structure. In addition, the area of the fine equiaxial grain structure was reduced obviously with the increase in welding speed. Full article
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20 pages, 31298 KiB  
Article
Additive Manufacturing and Precipitation Hardening of Low-Alloyed Copper Alloys Containing Chromium and Hafnium
by Julia Dölling, Samira Gruber, Felix Kovermann, Lukas Stepien, Elmar Beeh, Elena Lopez, Christoph Leyens, Hans-Günther Wobker and Andreas Zilly
Metals 2024, 14(11), 1304; https://doi.org/10.3390/met14111304 - 19 Nov 2024
Viewed by 650
Abstract
Copper alloys with chromium and hafnium offer the possibility of precipitation hardening and combine enhanced strength with high electrical and thermal conductivities. The production process, which starts with raw materials, involves powder production by gas atomization and leads to additive manufacturing by laser [...] Read more.
Copper alloys with chromium and hafnium offer the possibility of precipitation hardening and combine enhanced strength with high electrical and thermal conductivities. The production process, which starts with raw materials, involves powder production by gas atomization and leads to additive manufacturing by laser powder bed fusion with different parameter sets. The aim is to utilize precipitation reactions afterwards in CuHf0.7Cr0.35 during temperature exposure for further property optimization. This research focuses on the low-alloyed copper alloy with hafnium and chromium, compares this with conventionally manufactured specimens, and relates the alloy to additively manufactured specimens of other benchmark alloys such as CuCr1Zr. Measurements of hardness and electrical conductivity are accompanied by metallographic investigations to understand the behavior of CuHf0.7Cr0.35 manufactured by generative methods. In the as-built condition, melting traces remain visible in the microstructure, and hardness values of 101 HV and an electrical conductivity of 17.5 MS/m are reached. Solution annealing completely recrystallizes the microstructure, and the following quenching holds further alloying elements in supersaturated solid solution, resulting in 73 HV and 16.5 MS/m. Subsequent target-oriented precipitation reactions enable peak values of about 190 HV and 42 MS/m. Future research will assess mechanical and physical properties at elevated temperatures and evaluate possible applications. Full article
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12 pages, 5433 KiB  
Article
Low-Acid Leaching for Preferential Lithium Extraction and Preparation of Lithium Carbonate from Rare Earth Molten Salt Electrolytic Slag
by Zaoming Chen, Ruzhen Peng, Zhen Xiang, Fupeng Liu, Jinliang Wang and Xirong Chen
Metals 2024, 14(11), 1303; https://doi.org/10.3390/met14111303 - 19 Nov 2024
Viewed by 450
Abstract
In this work, lithium was preferentially recovered through the low-acid leaching from rare earth molten salt electrolytic slag (REMSES) with a leaching temperature of 60 °C. The influence on lithium extraction was investigated in detail in different leaching conditions. The optimal conditions were [...] Read more.
In this work, lithium was preferentially recovered through the low-acid leaching from rare earth molten salt electrolytic slag (REMSES) with a leaching temperature of 60 °C. The influence on lithium extraction was investigated in detail in different leaching conditions. The optimal conditions were as follows: liquid-to-solid ratio (10 mL/g), sulfuric acid concentration (0.8 mol/L), leaching time (60 min) and leaching temperature (60 °C). This yielded a lithium extraction rate of 98.52% and a lithium carbonate purity of 99.5%. It was fitted using an empirical model; the kinetics showed that internal diffusion control conformed to the low-acid leaching reaction, which had an apparent activation energy of 10.81 kJ/mol for lithium. The total profit from the whole process was USD 0.2576 when dealing with 1.0 kg of REMSES. Moreover, in the sulfuric acid system, the leaching reaction mechanism was carefully investigated between 30 and 90 °C. An innovative process of recovering lithium from REMSES was achieved with environmental friendliness and good economic returns. Compared to traditional leaching using concentrated sulfuric acid, this cleaner recycling method conforms to the concept of green, low-carbon sustainable development, with high lithium selectivity, low impurity content in the filtrate and low acid consumption. Full article
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17 pages, 2689 KiB  
Article
Microstructural and Magnetic Characteristics of High-Entropy FeCoNiMnTi Alloy Produced via Mechanical Alloying
by Chérif Ben Ammar, Nawel Khitouni, Marzook Alshammari, Abdulrahman Alsawi, Mohamed Khitouni, Joan-Josep Suñol and Mahmoud Chemingui
Metals 2024, 14(11), 1302; https://doi.org/10.3390/met14111302 - 18 Nov 2024
Viewed by 610
Abstract
In the current study, X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometer techniques were used to examine the impact of milling time on the microstructural and magnetic characteristics of Fe30Co20Ni20Mn20Ti10 (at%) produced via [...] Read more.
In the current study, X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometer techniques were used to examine the impact of milling time on the microstructural and magnetic characteristics of Fe30Co20Ni20Mn20Ti10 (at%) produced via mechanical alloying. Results demonstrate that phase change is dependent on up to 30 h of milling. In terms of the hcp-Fe2Ti intermetallic and the BCC-FeCoNiMnTi supersaturated solid solution, the system maintains its two-phase structure at higher times. Additionally, the final average crystallite size was estimated to be approximately 10 nm, and the lattice strain was found to be between 0.95 and 1.15%. As a function of milling time, the magnetic properties are discussed with the microstructural and crystallographic alterations. The collected powder after 100 h of milling has an Ms value of 28 emu/g and a Hc value of 25 Am−1, which is consistent with exceptional soft magnetics. This is essentially due to the Fe2Ti intermetallic and the BCC-Fe-based solid solution production, together with the refinement of the crystallite size. Furthermore, the presence of paramagnetic Ti atoms in solid solution and the development of high densities of defects and interfaces have been connected to the low value of Ms. Full article
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35 pages, 16105 KiB  
Article
The Study and Application on Ductile Fracture Criterion of Dual Phase Steels During Forming
by Lianxing Zhao, Xiaotao Fei, Chaifeng Sun, Peng Liu and Di Li
Metals 2024, 14(11), 1301; https://doi.org/10.3390/met14111301 - 18 Nov 2024
Viewed by 523
Abstract
High-strength steel exhibits complex fracture behavior due to the interplay between shear and necking mechanisms during stamping and forming processes, posing challenges to achieving the dimensional accuracy and reliability demanded for automotive body panels. Existing prediction methods often fail to simultaneously account for [...] Read more.
High-strength steel exhibits complex fracture behavior due to the interplay between shear and necking mechanisms during stamping and forming processes, posing challenges to achieving the dimensional accuracy and reliability demanded for automotive body panels. Existing prediction methods often fail to simultaneously account for both tensile and shear fracture characteristics, thereby limiting their predictive accuracy under diverse stress conditions. To address this limitation, we propose a ductile fracture criterion that integrates both tensile and shear mechanisms, calibrated using a single tensile–shear test to facilitate practical engineering applications. This study investigates the fracture characteristics of DP780 dual-phase steel through numerical analysis and tensile–shear experiments. The findings establish a relationship between stress triaxiality and ultimate fracture strain across varying stress states, represented by the B–W curve. Simulations reveal distinct stress triaxiality behaviors under different loading conditions: under uniaxial tensile loading, triaxiality ranges from 0.33 to 0.6, with fracture strain decreasing monotonically as triaxiality increases. Under shear loading, triaxiality ranges from 0 to 0.33, with fracture strain increasing monotonically as triaxiality rises. Additional bending simulations validate that this criterion, along with the B–W curve, reliably predicts the fracture behavior of DP780, offering an effective tool for predicting fracture in dual-phase steels during stamping and forming processes. Full article
(This article belongs to the Section Metal Casting, Forming and Heat Treatment)
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15 pages, 18440 KiB  
Article
Evaluation of Continuous GMA Welding Characteristics Based on the Copper-Plating Method of Solid Wire Surfaces
by Dong-Yoon Kim and Jiyoung Yu
Metals 2024, 14(11), 1300; https://doi.org/10.3390/met14111300 - 18 Nov 2024
Viewed by 487
Abstract
Gas metal arc welding (GMAW) is widely used in various industries, such as automotive and heavy equipment manufacturing, because of its high productivity and speed, with solid wires being selected based on the mechanical properties required for welded joints. GMAW consists of various [...] Read more.
Gas metal arc welding (GMAW) is widely used in various industries, such as automotive and heavy equipment manufacturing, because of its high productivity and speed, with solid wires being selected based on the mechanical properties required for welded joints. GMAW consists of various components, among which consumables such as the contact tip and continuously fed solid wire have a significant impact on the weld quality. In particular, the copper-plating method can affect the conductivity and arc stability of the solid wire, causing differences in the continuous welding performance. This study evaluated the welding performance during 60 min continuous GMAW using an AWS A5.18 ER70S-3 solid wire, which was copper-plated using chemical plating (C-wire) and electroplating (E-wire). The homogeneity and adhesion of the copper-plated surface of the E-wire were superior to those of the C-wire. The E-wire exhibited better performance in terms of arc stability. The wear rate of the contact tip was approximately 45% higher when using the E-wire for 60 min of welding compared with the C-wire, which was attributed to the larger variation rate in the cast and helix in the E-wire. Additionally, the amount of spatter adhered to the nozzle during 60 min, with the E-wire averaging 5.9 g, approximately half that of the C-wire at 12.9 g. The E-wire exhibits superior arc stability compared with the C-wire based on the spatter amount adhered to the nozzle. This study provides an important reference for understanding the impact of copper plating methods and wire morphology on the replacement cycles of consumable welding parts in automated welding processes such as continuous welding and wire-arc additive manufacturing. Full article
(This article belongs to the Special Issue Welding and Joining of Advanced High-Strength Steels (2nd Edition))
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12 pages, 4713 KiB  
Article
Liquid Metal Leaching for Rare Earth Magnet Recycling
by Emmanuel Opoku, Chinenye Chinwego, Adam Powell and Brajendra Mishra
Metals 2024, 14(11), 1299; https://doi.org/10.3390/met14111299 - 18 Nov 2024
Viewed by 499
Abstract
This study investigates the optimization of liquid metal leaching for recycling rare earth elements (REEs) from NdFeB magnets, a critical step in addressing the increasing demand for these materials in various high-tech applications. We explored the effects of leaching time, stirring, and magnet [...] Read more.
This study investigates the optimization of liquid metal leaching for recycling rare earth elements (REEs) from NdFeB magnets, a critical step in addressing the increasing demand for these materials in various high-tech applications. We explored the effects of leaching time, stirring, and magnet demagnetization on the yield of the leaching process using molten magnesium. Conducted at 900 °C, our experiments assessed the leaching process over periods of 2, 3.5, and 5 h, with and without the application of stirring. Our findings show that longer leaching times considerably increase neodymium (Nd) and praseodymium (Pr) leaching yield, with a notable peak in efficiency found at 5 h. Stirring improved the uniformity of REEs significantly and resulted in up to 80% yield. Furthermore, our data show that pre-leaching magnet demagnetization improves leaching specificity, significantly reducing the presence of non-target metals like nickel and copper. These insights offer a pathway to more cost-effective recycling of REEs from magnet scrap, which is essential for environmentally conscious management of resources amid the escalating global demand for REEs. Full article
(This article belongs to the Special Issue Metal Processing for Sustainability)
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10 pages, 12436 KiB  
Article
Analysis of Stored Energy Distribution in Three Directions of Tantalum in Deformed and Annealed States
by Yanjun Zhou, Yahui Liu, Qianqian Zhu and Shaodan Yang
Metals 2024, 14(11), 1298; https://doi.org/10.3390/met14111298 - 17 Nov 2024
Viewed by 439
Abstract
Microstructures in high-purity tantalum (Ta) were analyzed in three directions, focusing on the evolution of stored energy during rolling and heating processes. Results indicated significant fluctuation in the transaction direction (TD) surface, which was observed in both deformed and annealed states. This phenomenon [...] Read more.
Microstructures in high-purity tantalum (Ta) were analyzed in three directions, focusing on the evolution of stored energy during rolling and heating processes. Results indicated significant fluctuation in the transaction direction (TD) surface, which was observed in both deformed and annealed states. This phenomenon is attributed to the alternately arranged {111}<uvw>(<111>//normal direction (ND)) and {100}<uvw>(<100>//ND) oriented grains, coupled with the substantial energy difference between them, even after 12 passes. Additionally, through the estimation and calculation of stored energy based on band contrast from electron backscatter diffraction and X-ray line profile analyses, the recovery kinetics for different directions and grain types were quantitatively assessed. Findings revealed that the dislocation density of {111} grains decreased significantly more than that of {100} grains when annealed at 1073 K. The degree of recovery was closely related to temperature, dislocation density, and dislocation type. Full article
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14 pages, 5811 KiB  
Article
Influence of Cold-Rolling Processes on the Dimensional Accuracy and Roughness of Small-Diameter Thick-Walled Seamless Tubes
by Xiuping Ding, Ran Li, Pengfei Jin, Weijie Wang, Cheng Zhang, Minyu Ma and Jinfeng Huang
Metals 2024, 14(11), 1297; https://doi.org/10.3390/met14111297 - 16 Nov 2024
Viewed by 444
Abstract
Cold pilgering is widely utilized in high-end applications for the precise shaping of seamless tubes due to its capacity for large deformation, which reduces the number of deformation processes and shortens production cycles. However, there is a gap in the research on the [...] Read more.
Cold pilgering is widely utilized in high-end applications for the precise shaping of seamless tubes due to its capacity for large deformation, which reduces the number of deformation processes and shortens production cycles. However, there is a gap in the research on the cold pilgering of small-diameter, thick-walled seamless tubes, specifically those with an outer diameter–wall thickness ratio of ≤3. In this study, cold pilgering tests were performed on Cr-Mo-V hot-working die steel small-diameter thick-walled tubes. It was discovered that increasing the feed rate results in greater deviations in both inner diameter and wall thickness, although it has little effect on inner wall roughness. In contrast, increasing wall thickness reduction leads to higher wall thickness deviation but reduces inner surface roughness without significantly affecting inner diameter deviation. The study also found that a decrease in the initial inner wall roughness before pilgering results in improved final roughness. Under optimal conditions, the average inner surface roughness Sa can reach 0.177 μm, and small-diameter thick-walled seamless tubes with deviations in the inner diameter and wall thickness of 0.05 mm and 0.03 mm, respectively, are obtained. After tempering at 600 °C, the tensile strength (Rm) and yield strength (Rp0.2) of the cold-pilgered tube reach 1092 MPa and 947 MPa, respectively, and the elongation (δ5%) and impact energy (AkU) increase to 20.4% and 61.5 J, respectively. Full article
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53 pages, 24284 KiB  
Review
Multi-Metal Additive Manufacturing by Extrusion-Based 3D Printing for Structural Applications: A Review
by Alina Mazeeva, Dmitriy Masaylo, Gleb Konov and Anatoliy Popovich
Metals 2024, 14(11), 1296; https://doi.org/10.3390/met14111296 - 16 Nov 2024
Viewed by 760
Abstract
Additive manufacturing (AM) is a rapidly developing technical field that is becoming an irreplaceable tool to fabricate unique complex-shaped parts in aerospace, the automotive industry, medicine, and so on. One of the most promising directions for AM application is the design and production [...] Read more.
Additive manufacturing (AM) is a rapidly developing technical field that is becoming an irreplaceable tool to fabricate unique complex-shaped parts in aerospace, the automotive industry, medicine, and so on. One of the most promising directions for AM application is the design and production of multi-material components with different types of chemical, structural, and architectural gradients that also promote a breakthrough in bio-inspired approaches. At the moment there are a lot of different AM techniques involving various types of materials. This paper represents a review of extrusion-based AM techniques using metal-polymer composites for structural metal parts fabrication. These methods are significantly cheaper than powder bed fusion (PBF) and directed energy deposition (DED) techniques, though have a lower degree of part detail. Thus, they can be used for low-scale production of the parts that are not rentable to produce with PBF and DED. Multi-material structures application in machinery, main aspects of feedstock preparation, the subsequent steps of extrusion-based 3D printing, and the following treatment for manufacturing single-metallic and multi-metallic parts are considered. Main challenges and recommendations are also discussed. Multi-metallic extrusion-based 3D printing is just a nascent trend requiring further wide investigation, though even now it shows pretty interesting results. Full article
(This article belongs to the Section Additive Manufacturing)
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11 pages, 2093 KiB  
Article
An Improved Process for Solving the Sintering Problem of Al-Si Alloy Powder Metallurgy
by Hexin Tian, Fachang Zhao, Dongmei Ma, Xingming Zhao, Jingran Meng, Guangan Zhang and Fufa Wu
Metals 2024, 14(11), 1295; https://doi.org/10.3390/met14111295 - 16 Nov 2024
Viewed by 567
Abstract
The Al-Si alloy prepared by the traditional powder metallurgy method has the problems of difficult sintering and low mechanical properties. In this paper, rotary extrusion combined with rapid solidification/powder metallurgy technology (RS/PM) is proposed and designed to produce an Al-10Si alloy. In subsequent [...] Read more.
The Al-Si alloy prepared by the traditional powder metallurgy method has the problems of difficult sintering and low mechanical properties. In this paper, rotary extrusion combined with rapid solidification/powder metallurgy technology (RS/PM) is proposed and designed to produce an Al-10Si alloy. In subsequent sintering at different temperatures, better metallurgical bonding between particles can be achieved to fulfil the aim of improving the mechanical properties of the material. Additionally, the continuous preparation of materials can be achieved. Finally, it is verified that the density of the Al-10Si alloy sintered at 525 °C is 2.61 g/cm3, reaching 97.0% of the theoretical density, and the tensile strength reaches 336 MPa, which is much higher than that of the alloy prepared by the traditional casting method and powder metallurgy method. Full article
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16 pages, 5358 KiB  
Article
High-Entropy Alloy Laser Cladding with Cable-Type Welding Wire: Experimental Study and First-Principles Calculations
by Wenjun Wang, Yifei Zheng, Zhihui Cai, Wenjian Zheng, Cai Zhang, Yu Wang, Zhiyong Zhao, Daochen Feng, Yinghe Ma and Jianguo Yang
Metals 2024, 14(11), 1294; https://doi.org/10.3390/met14111294 - 16 Nov 2024
Viewed by 719
Abstract
The Co-Cr-Fe-Ni high-entropy alloy (HEA) is particularly suitable for preparing coatings due to its excellent comprehensive properties. In this study, we use the laser cladding method to prepare Co-Cr-Fe-Ni HEA coatings with Co-Cr-Fe-Ni cable-type welding wire (CTWW) as the filling material and investigated [...] Read more.
The Co-Cr-Fe-Ni high-entropy alloy (HEA) is particularly suitable for preparing coatings due to its excellent comprehensive properties. In this study, we use the laser cladding method to prepare Co-Cr-Fe-Ni HEA coatings with Co-Cr-Fe-Ni cable-type welding wire (CTWW) as the filling material and investigated the dilution rates of the coatings by experimental studies and first-principles calculations. The dilution rate is reduced to about 50% by changing the wire feeding speed, and a Co-Cr-Fe-Ni HEA coating with near nominal composition was prepared by multi-layer cladding. The HEA coating with near nominal composition is successfully prepared in the fourth layer of cladding. The coating is dense and uniform, with good metallurgical bonding. The mechanical properties of the coating were explored using first-principles calculations. All four coatings exhibit a single face-centered cubic (FCC) phase with good mechanical stability in the ground state. The bulk modulus B, shear modulus G, and Young’s modulus E of the four layers of coatings are gradually decreasing from B = 202 GPa, G = 136 GPa, and E = 334 GPa to B = 239 GPa, G = 154 GPa, and E = 380 GPa. The brittleness of the coating shows a trend of first decreasing and then increasing, and the coating closest to the nominal composition has the highest brittleness. Full article
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18 pages, 14402 KiB  
Article
Steel Chips as a Raw Material for MEX
by Catarina Duarte Batista and Maria Teresa Freire Vieira
Metals 2024, 14(11), 1293; https://doi.org/10.3390/met14111293 - 15 Nov 2024
Viewed by 478
Abstract
In recent years, metal chip powders obtained from solid-state processes have shown great potential as a sustainable raw material for powder technologies. The material and fragmentation process of the chips has a significant role in the final characteristics of the powder particles, such [...] Read more.
In recent years, metal chip powders obtained from solid-state processes have shown great potential as a sustainable raw material for powder technologies. The material and fragmentation process of the chips has a significant role in the final characteristics of the powder particles, such as size and particle size distribution, shape, surface, and structure, which are essential parameters to consider when converting chips to powder for applications. However, tool steel chips as a powder raw material have not yet been significantly studied. In this study, the steel chips were from machining AISI H13 steel and the milling process used a ball mill, and the challenge was to obtain powder particle sizes of around 20 µm with suitable properties from the application of envisaged material extrusion (MEX). A comparison study with the commercial raw material for MEX, such as powder metal filament extrusion, was performed. This study highlights the behaviors of chip powders during all steps of MEX, namely, feedstock and filament production, 3D object shaping, thermal de-binding, and sintering. A comparison of the mixture based on powder from chips and commercial powders for MEX was performed after evaluating the mixing torque of the powder and the system of binders and additives suitable for the rheological characteristics required for an extrusion mixture, and optimizing the binder removal and the sintering conditions. The 3D objects resulting from chip powders had a refined microstructure, showing an increase of 15% in the microhardness when compared with the those resulting from commercial powders. Full article
(This article belongs to the Special Issue Advances in Recycling and Reuse of Metals)
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32 pages, 16212 KiB  
Article
Modeling and Monitoring of the Tool Temperature During Continuous and Interrupted Turning with Cutting Fluid
by Hui Liu, Markus Meurer and Thomas Bergs
Metals 2024, 14(11), 1292; https://doi.org/10.3390/met14111292 - 15 Nov 2024
Viewed by 499
Abstract
In metal cutting, a large amount of mechanical energy converts into heat, leading to a rapid temperature rise. Excessive heat accelerates tool wear, shortens tool life, and hinders chip breakage. Most existing thermal studies have focused on dry machining, with limited research on [...] Read more.
In metal cutting, a large amount of mechanical energy converts into heat, leading to a rapid temperature rise. Excessive heat accelerates tool wear, shortens tool life, and hinders chip breakage. Most existing thermal studies have focused on dry machining, with limited research on the effects of cutting fluids. This study addresses that gap by investigating the thermal behavior of cutting tools during continuous and interrupted turning with cutting fluid. Tool temperatures were first measured experimentally by embedding a thermocouple in a defined position within the tool. These experimental results were then combined with simulations to evaluate temperature changes, heat partition, and cooling efficiency under various cutting conditions. This work presents novel analytical and numerical models. Both models accurately predicted the temperature distribution, with the analytical model offering a computationally more efficient solution for industrial use. Experimental results showed that tool temperature increased with cutting speed, feed, and cutting depth, but the heat partition into the tool decreased. In continuous cutting, cooling efficiency was mainly influenced by feed rate and cutting depth, while cutting speed had minimal impact. Interrupted cutting improved cooling efficiency, as the absence of chips and workpieces during non-cutting phases allowed the cutting fluid to flow over the tool surface at higher speeds. The convective cooling coefficient was determined through inverse calibration. A comparative analysis of the analytical and numerical simulations revealed that the analytical model can underestimate the temperature distribution for complex tool structures, particularly non-orthogonal hexahedral geometries. However, the relative error remained consistent across different cutting conditions, with less error observed in interrupted cutting compared to continuous cutting. These findings highlight the potential of analytical models for optimizing thermal management in metal turning processes. Full article
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17 pages, 1631 KiB  
Review
Three-Dimensional Printing of Metallic Parts by Means of Fused Filament Fabrication (FFF)
by Irene Buj-Corral, Felip Fenollosa-Artés and Joaquim Minguella-Canela
Metals 2024, 14(11), 1291; https://doi.org/10.3390/met14111291 - 14 Nov 2024
Viewed by 613
Abstract
Obtaining metallic parts via Additive Manufacturing can yield several advantages over using other traditional manufacturing methods such as machining. Material extrusion (MEX) can handle complex shapes with porous structures and, at the present time, much low-end and desktop equipment is available. In the [...] Read more.
Obtaining metallic parts via Additive Manufacturing can yield several advantages over using other traditional manufacturing methods such as machining. Material extrusion (MEX) can handle complex shapes with porous structures and, at the present time, much low-end and desktop equipment is available. In the present work, different industrial and medical applications of metallic Fused Filament Fabrication (FFF) parts are presented. First, an overview of the process, equipment, and of the metal-filled filaments currently available is provided. Then, the properties of parts and different applications are shown. For example, metal-filled filaments with a low metal content that can be used to obtain plastic parts with metallic appearance (with either steel, copper, or bronze), and filaments with a high metallic content allow obtaining metallic parts with high mechanical strength after a sintering operation. The present contribution aims to be an up-to-date panorama for current industrial and medical results and lessons learnt from the application of FFF to obtain metallic parts. Full article
(This article belongs to the Section Additive Manufacturing)
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17 pages, 23471 KiB  
Article
An Analysis of Dynamic Recrystallization During the Reduction Pretreatment Process Using a Multiscale Model
by Die Wu, Zhen Ning, Yanlin Zhu and Wei Yu
Metals 2024, 14(11), 1290; https://doi.org/10.3390/met14111290 - 14 Nov 2024
Viewed by 512
Abstract
In this study, a multiscale model is developed through secondary development (UMAT and UEXTERNALDB) in Abaqus with the objective of simulating the thermal deformation process with dynamic recrystallization behavior. The model couples the finite element method (FEM) with the multiphase field model (MPFM), [...] Read more.
In this study, a multiscale model is developed through secondary development (UMAT and UEXTERNALDB) in Abaqus with the objective of simulating the thermal deformation process with dynamic recrystallization behavior. The model couples the finite element method (FEM) with the multiphase field model (MPFM), thereby establishing bidirectional coupling between macroscopic mechanical behavior and microstructural evolution. A comparison between the single-element hot compression simulation and experimental results demonstrates that the model accurately simulates both the macroscopic mechanical behavior and microstructural evolution during the thermal deformation process, thereby exhibiting high precision. Simulations of the reduction pretreatment (RP) process under different reduction amounts and billet surface temperatures demonstrate that increasing the reduction amount and billet surface temperature significantly enhances both plastic deformation and the volume fraction of dynamic recrystallization in the billet core. This results in the closure of core voids and the refinement of the core microstructure, thereby providing valuable guidance for the development of optimal reduction pretreatment (RP) processes. Full article
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13 pages, 34577 KiB  
Article
The Effects of Straw-Returning Processes on the Formation of Fe-Mn (Hydr)oxide Colloids and Arsenic Bioavailability
by Junhao Zheng, Mei Jiang, Qingzhu Li, Zhihui Yang, Qi Liao, Mengying Si and Weichun Yang
Metals 2024, 14(11), 1289; https://doi.org/10.3390/met14111289 - 14 Nov 2024
Viewed by 403
Abstract
The objective of this study was to investigate the effect of straw return on the formation of Fe-Mn colloids in arsenic-contaminated soils and its subsequent influence on arsenic behavior. It was observed that organic matter (SD) resulting from straw decomposition interacted with iron/manganese [...] Read more.
The objective of this study was to investigate the effect of straw return on the formation of Fe-Mn colloids in arsenic-contaminated soils and its subsequent influence on arsenic behavior. It was observed that organic matter (SD) resulting from straw decomposition interacted with iron/manganese (hydr)oxides (Fe/Mn (hydr)oxides) present in the soil, leading to the formation of colloidal particles. These particles significantly influenced the fixation and release of arsenic. The experimental results indicated that an increase in SD content facilitated the formation of colloidal particles. The highest concentration of colloidal particles was observed at a C/Fe-Mn ratio of 2.2, which significantly reduced the bioavailability and mobility of arsenic in the soil. The increase in SD content also diminished the depositional attachment efficiency of SD/Fe-Mn, thereby enhancing its migration through the soil. The actual field soil-filled column experiments further demonstrated that the content of SD significantly influenced arsenic bioavailability and mobility. Specifically, at a C/Fe-Mn ratio of 2.2, the inhibition of arsenic migration and bioavailability was found to be 1.46 times more effective compared to a C/Fe-Mn ratio of 0.4. Therefore, the return of straw to the field represents an effective soil remediation strategy for mitigating the bioavailability of arsenic by modulating the C/Fe-Mn ratio. This approach offers a novel perspective on strategies for heavy metal remediation. Full article
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14 pages, 3603 KiB  
Article
Preparation of Titanium Metal by Deoxygenation Under KCl-NaCl-YCl3 System Using Soluble Anode
by Tianzhu Mu, Fuxing Zhu, Yan Zhao, Haoyu Fang, Haohang Ji and Lei Gao
Metals 2024, 14(11), 1288; https://doi.org/10.3390/met14111288 - 14 Nov 2024
Viewed by 510
Abstract
Titanium metal is primarily produced via the Kroll process, which is characterized by a semi-continuous production flow and a lengthy process cycle, resulting in high production costs. Researchers have explored alternative methods for titanium production, including molten salt electrolysis, such as the Fray–Farthing–Chen [...] Read more.
Titanium metal is primarily produced via the Kroll process, which is characterized by a semi-continuous production flow and a lengthy process cycle, resulting in high production costs. Researchers have explored alternative methods for titanium production, including molten salt electrolysis, such as the Fray–Farthing–Chen (FFC), Ono Suzuki (OS), and University of Science and Technology Beijing (USTB) processes, aiming to achieve more economical production. Among these, the USTB process, a representative of soluble anode electrolysis, has shown significant promise. However, controlling oxygen concentration in titanium produced by soluble anode electrolysis remains a challenge. This study proposes a novel approach to enhance deoxidation efficiency in soluble anode electrolysis for titanium production by introducing yttrium chloride (YCl3) into the molten salt electrolyte. Thermodynamic analysis and experimental validation demonstrate that the theoretical deoxidation limit for titanium can reach below 100 ppm under Y/YOCl/YCl3 equilibrium. We report the successful synthesis of titanium powder with an oxygen concentration of 6000 ppm from titanium-carbon-oxygen solid solution. Under optimized conditions, the purity of the titanium powder reached 99.42%, demonstrating a new approach for producing high-purity titanium. This method, based on soluble anode electrolysis, offers a potential alternative to the conventional Kroll process. The research elucidates the fabrication process and analytical methods for titanium-carbon-oxygen solid solution, and employs a combination of analytical techniques, including XRD, SEM-EDS, and ONH Analyzer, for characterization of the electrolytic product, encompassing phase analysis, microstructure, and oxygen concentration testing. Full article
(This article belongs to the Special Issue Metallurgy Investigation in Nonferrous Metal Smelting)
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37 pages, 6444 KiB  
Review
The Role of Precipitates in Hydrogen Embrittlement of Precipitation-Hardenable Aluminum Alloys
by Terezie Košová Altnerová, Darja Rudomilova, Pavel Novák and Tomáš Prošek
Metals 2024, 14(11), 1287; https://doi.org/10.3390/met14111287 - 14 Nov 2024
Viewed by 735
Abstract
This review examines hydrogen embrittlement (HE) in precipitation-hardenable aluminum alloys, focusing on the role of precipitates as hydrogen traps. It covers hydrogen entry mechanisms, the effects of microstructural features such as dislocations and grain boundaries, and secondary phase evolution during heat treatment. The [...] Read more.
This review examines hydrogen embrittlement (HE) in precipitation-hardenable aluminum alloys, focusing on the role of precipitates as hydrogen traps. It covers hydrogen entry mechanisms, the effects of microstructural features such as dislocations and grain boundaries, and secondary phase evolution during heat treatment. The interaction between hydrogen and precipitates, including the role of coherent and incoherent interfaces, is analyzed in view of the impact on HE susceptibility. Various techniques used to assess the interaction between hydrogen and aluminum alloys are also compared. The goal is to summarize the state-of-the-art understanding of the microstructural factors influencing the resistance of aluminum alloys to HE. Full article
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16 pages, 3429 KiB  
Article
Enhancement of the Electrical Conductivity and Mechanical Properties of Al-Mg-Si and Al-Mg-Zn Ternary Systems After a T8 Heat Treatment
by Xóchitl Atanacio-Sánchez, Carlos Gamaliel Garay-Reyes, Alfredo Martínez-García, Ivanovich Estrada-Guel, José Manuel Mendoza-Duarte, Pedro Guerrero-Seañez, Sergio González-Sánchez, Enrique Rocha-Rangel, José de Jesús Cruz-Rivera, Emmanuel José Gutiérrez-Castañeda and Roberto Martínez-Sánchez
Metals 2024, 14(11), 1286; https://doi.org/10.3390/met14111286 - 13 Nov 2024
Viewed by 580
Abstract
The present research focuses on enhancing the mechanical properties and the electrical conductivity of alloys corresponding to the Al-Mg-Zn (two different compositions) and Al-Mg-Si systems, compared with the commercial 6201-T8 and 1350-H16 alloys, by using a novel approach based on T8 tempering (solution [...] Read more.
The present research focuses on enhancing the mechanical properties and the electrical conductivity of alloys corresponding to the Al-Mg-Zn (two different compositions) and Al-Mg-Si systems, compared with the commercial 6201-T8 and 1350-H16 alloys, by using a novel approach based on T8 tempering (solution heat treated, cold worked, then artificially aged). After T8 tempering, the Al-Mg-Zn and Al-Mg-Si alloy systems show a better combination of electrical and mechanical properties, with an enhancement of the electrical conductivity by about 2.8% compared to that of 1350 alloy and 13% higher than for the 6201 alloy series. All studied alloys exhibit better mechanical properties than 1350-H16 and are similar to those of 6201-T8. Full article
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32 pages, 7537 KiB  
Review
Hydrogen Embrittlement of Galvanized Press-Hardened Steels: A Review
by Tomáš Kročil, Nikola Macháčková, Tomáš Prošek, Thomas Steck and Reza Sharif
Metals 2024, 14(11), 1285; https://doi.org/10.3390/met14111285 - 12 Nov 2024
Viewed by 684
Abstract
Press-hardened steels (PHS), as an alternative to traditional steels and aluminum alloys, combine great mechanical performance with low manufacturing costs. PHS are martensitic steels with ultimate tensile strength (UTS) up to 2000 MPa. These steels are commonly coated with zinc-based coatings (PHS GI) [...] Read more.
Press-hardened steels (PHS), as an alternative to traditional steels and aluminum alloys, combine great mechanical performance with low manufacturing costs. PHS are martensitic steels with ultimate tensile strength (UTS) up to 2000 MPa. These steels are commonly coated with zinc-based coatings (PHS GI) consisting of multiple Zn–Fe phases to enhance corrosion resistance. However, similar to all high-strength steels, PHS are known for their elevated susceptibility to hydrogen embrittlement (HE). Absorption of atomic hydrogen into the steel lattice can lead to a transition from a ductile to a brittle fracture mechanism and decrease the stress necessary for fracture initiation. This review examines the microstructure of PHS GI with a focus on how the manufacturing process influences key parameters of the coating. The material’s susceptibility to HE is discussed in the following sections, along with the potential for hydrogen introduction through corrosion in atmospheric environments. The relationship between the content of hydrogen and its effects on fracture behavior is discussed, along with the corrosion behavior of PHS GI. The potential areas for future research and development of PHS GI with increased HE resistance are proposed. Full article
(This article belongs to the Special Issue Recent Advances in High-Performance Steel)
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14 pages, 3525 KiB  
Article
Electrochemical Analysis on Intergranular Corrosion of Austenitic Stainless Steel Weld in Molten Nitrate Salt
by Noparat Kanjanaprayut, Thamrongsin Siripongsakul, Panya Wiman, Wannapha Issaard, Thanasak Nilsonthi and Piyorose Promdirek
Metals 2024, 14(11), 1284; https://doi.org/10.3390/met14111284 - 12 Nov 2024
Viewed by 711
Abstract
An investigation of intergranular corrosion (IGC) sensitization in molten nitrate salts of austenitic stainless steel welds of AISI 304, AISI 304H, and AISI321 produced by GTAW with ER 308L and ER 347 fillers was performed. The degree of sensitization (DOS) to IGC was [...] Read more.
An investigation of intergranular corrosion (IGC) sensitization in molten nitrate salts of austenitic stainless steel welds of AISI 304, AISI 304H, and AISI321 produced by GTAW with ER 308L and ER 347 fillers was performed. The degree of sensitization (DOS) to IGC was assessed using a double loop electrochemical potentiokinetic reactivation and pitting potential. It was found that DOS levels in weld zones were quite low, not exceeding 15%, while those in HAZs were up to 60% after exposure at 600 °C for 300 h. The low DOS levels were due to low carbide precipitation. However, another cause of DOS was the delta-ferrite to sigma transformation in weld zones. Linear sweep voltammetry was used to quantify the sigma phase. Full article
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28 pages, 6631 KiB  
Review
Recent Advances in Hybrid Nanocomposites for Aerospace Applications
by Beatriz Monteiro and Sónia Simões
Metals 2024, 14(11), 1283; https://doi.org/10.3390/met14111283 - 12 Nov 2024
Viewed by 950
Abstract
Hybrid nanocomposites have emerged as a groundbreaking class of materials in the aerospace industry, offering exceptional mechanical, thermal, and functional properties. These materials, composed of a combination of metallic matrices (based on aluminum, magnesium, or titanium) reinforced with a mixture of nanoscale particles, [...] Read more.
Hybrid nanocomposites have emerged as a groundbreaking class of materials in the aerospace industry, offering exceptional mechanical, thermal, and functional properties. These materials, composed of a combination of metallic matrices (based on aluminum, magnesium, or titanium) reinforced with a mixture of nanoscale particles, such as carbon nanotubes (CNTs), graphene, and ceramic nanoparticles (SiC, Al2O3), provide a unique balance of high strength, low weight, and enhanced durability. Recent advances in developing these nanocomposites have focused on optimizing the dispersion and integration of nanoparticles within the matrix to achieve superior material performance. Innovative fabrication techniques have ensured uniform distribution and strong bonding between the matrix and the reinforcements, including advanced powder metallurgy, stir casting, in situ chemical vapor deposition (CVD), and additive manufacturing. These methods have enabled the production of hybrid nanocomposites with improved mechanical properties, such as increased tensile strength, fracture toughness, wear resistance, and enhanced thermal stability and electrical conductivity. Despite these advancements, challenges remain in preventing nanoparticle agglomeration due to the high surface energy and van der Walls forces and ensuring consistent quality and repeatability in large-scale production. Addressing these issues is critical for fully leveraging the potential of hybrid nanocomposites in aerospace applications, where materials are subjected to extreme conditions and rigorous performance standards. Ongoing research is focused on developing novel processing techniques and understanding the underlying mechanisms that govern the behavior of these materials under various operational conditions. This review highlights the recent progress in the design, fabrication, and application of hybrid nanocomposites for aerospace applications. It underscores their potential to revolutionize the industry by providing materials that meet the demanding requirements for lightweight, high-strength, and multifunctional components. Full article
(This article belongs to the Section Metal Matrix Composites)
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