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Metals, Volume 13, Issue 6 (June 2023) – 147 articles

Cover Story (view full-size image): EAF has the potential to decarbonize the steel industry. Carbon needs to be injected into molten slag for slag foaming in EAF steelmaking. Biocarbon is gaining attention as an alternative to fossil carbon. Two biochar candidates were tested in an induction furnace to simulate EAF conditions. The slag foaming height was measured and compared to fossil carbon candidates. The results show biochar has considerable slag foaming capacity, specifically in bio-briquette forms. Ongoing research aims to develop a standardized methodology for ranking and qualifying different biochar candidates for larger-scale use. View this paper
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13 pages, 2002 KiB  
Article
Modeling Segregation of Fe–C Alloy in Solidification by Phase-Field Method Coupled with Thermodynamics
by Tong-Zhao Gong, Yun Chen, Wei-Ye Hao, Xing-Qiu Chen and Dian-Zhong Li
Metals 2023, 13(6), 1148; https://doi.org/10.3390/met13061148 - 20 Jun 2023
Cited by 2 | Viewed by 1247
Abstract
The primary carbide in high carbon chromium bearing steels, which arises from solute segregation during non-equilibrium solidification, is one of the key factors affecting the mechanical properties and performance of the related components. In this work, the effects of carbide forming element diffusion, [...] Read more.
The primary carbide in high carbon chromium bearing steels, which arises from solute segregation during non-equilibrium solidification, is one of the key factors affecting the mechanical properties and performance of the related components. In this work, the effects of carbide forming element diffusion, primary austenite grain size, and the cooling rate on solute segregation and carbide precipitation during the solidification of an Fe–C binary alloy were studied by the phase-field method coupled with a thermodynamic database. It was clarified that increasing the ratio of solute diffusivity in solid and liquid, refining the grain size of primary austenite to lower than a critical value, and increasing the cooling rate can reduce the solute segregation and precipitation of primary carbide at late solidification. Two characteristic parameters were introduced to quantitatively evaluate the solute segregation during solidification including the phase fraction threshold of primary austenite when the solute concentration in liquid reaches the eutectic composition, and the maximum segregation ratio. Both parameters can be well-correlated to the ratio of solute diffusivity in solid and liquid, the grain size of primary austenite, and the cooling rate, which provides potential ways to control the solute segregation and precipitation of primary carbide in bearing steels. Full article
(This article belongs to the Special Issue Modeling of Alloy Solidification)
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13 pages, 1895 KiB  
Article
Rapid Fatigue Limit Estimation of Metallic Materials Using Thermography-Based Approach
by Zhanqi Liu, Haijiang Wang, Xueting Chen and Wei Wei
Metals 2023, 13(6), 1147; https://doi.org/10.3390/met13061147 - 20 Jun 2023
Cited by 2 | Viewed by 1152
Abstract
This work attempts to develop a theoretical model in combination with the representative volume element (RVE) theory for realizing rapid fatigue limit prediction. Within the thermodynamic framework, it is believed that two components, namely anelastic and microplastic behaviors, which correspond to recoverable and [...] Read more.
This work attempts to develop a theoretical model in combination with the representative volume element (RVE) theory for realizing rapid fatigue limit prediction. Within the thermodynamic framework, it is believed that two components, namely anelastic and microplastic behaviors, which correspond to recoverable and non-recoverable microstructural motions, contribute to temperature variation during high-cycle fatigue. Based on this, the constitutive equation of the response relationship between the temperature rise evolution and the stress amplitude of metallic materials can be deduced in combination with the heat balance equation. Meanwhile, a determination approach for the thermographic experimental data for accurate fatigue limit estimation is developed by combining it with a statistical method. Finally, the experimental data of metallic specimens and welded joints were utilized to validate the proposed model, and the results demonstrated great agreement between experimental and predicted data. Full article
(This article belongs to the Special Issue Fatigue Design of Steel and Composite Structures)
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13 pages, 4343 KiB  
Article
The Influence of Foaming Agents on Aluminium Foam Cell Morphology
by Tomislav Rodinger, Danko Ćorić and Željko Alar
Metals 2023, 13(6), 1146; https://doi.org/10.3390/met13061146 - 20 Jun 2023
Cited by 1 | Viewed by 1621
Abstract
The choice of foaming agent and its mass fraction significantly affect the size and number of metal foam cells. The powder metallurgy process was used to produce aluminium foams with the addition of various foaming agents: titanium hydride (TiH2) and calcium [...] Read more.
The choice of foaming agent and its mass fraction significantly affect the size and number of metal foam cells. The powder metallurgy process was used to produce aluminium foams with the addition of various foaming agents: titanium hydride (TiH2) and calcium carbonate (CaCO3). TiH2 was added in an amount of 0.4 wt.%, while the quantity of CaCO3 varied between 3 and 5 wt.%. The produced foams, with approximately the same degree of porosity, were scanned using a non-destructive computed tomography method. The number, size, equivalent diameter, sphericity, and compactness of cells were analysed on the obtained three-dimensional models. The results showed that foams foamed with TiH2 have much larger cells compared to CaCO3 agent. By considering the influence of CaCO3 fraction on the morphology of aluminium foam, it follows that a smaller quantity of CaCO3 (3 wt.%) provides a macrostructure with smaller cells. Samples with five wt.% CaCO3 contain slightly larger cells but are still much smaller than foams with TiH2 foaming agent at the same degree of porosity. The sphericity and compactness indicate that TiH2 foaming agent forms cells of a more regular shape compared to CaCO3 agent. Full article
(This article belongs to the Special Issue Structure and Application of Porous Metallic Materials)
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14 pages, 3252 KiB  
Article
Enhancement of Leaching Copper from Printed Circuit Boards of Discarded Mobile Phones Using Ultrasound–Ozone Integrated Approach
by Nguyen Thi Hong Hoa, Nguyen To Hoan, Nghia Nguyen Trong, Nguyen Thi Ngoc Linh, Bui Minh Quy, Thi Thu Ha Pham, Van Que Nguyen, Phuoc Nguyen Van and Vinh Dinh Nguyen
Metals 2023, 13(6), 1145; https://doi.org/10.3390/met13061145 - 20 Jun 2023
Cited by 1 | Viewed by 1453
Abstract
The recovery of metals from discarded mobile phones has been of interest due to its environmental and economic benefits. This work presents a simple and effective approach for leaching copper (Cu) from the printed circuit boards of discarded mobile phones by combining ultrasound [...] Read more.
The recovery of metals from discarded mobile phones has been of interest due to its environmental and economic benefits. This work presents a simple and effective approach for leaching copper (Cu) from the printed circuit boards of discarded mobile phones by combining ultrasound and ozone approaches. The X-ray diffraction (XRD) technique and Fourier-transform infrared spectroscopy (FT-IR) were used to characterize the solid phases, and inductively coupled plasma optical emission spectrometry (ICP-OES) was utilized to determine the concentration of metals in the liquid phases. The effects of several influential parameters, including ultrasound, ozone dose, HCl concentration, liquid/solid ratio, temperature, and reaction time on the leaching efficiency were investigated. The results showed that the optimal conditions for Cu leaching included an ozone dose of 700 mg/h, HCl concentration of 3.0 M, liquid/solid ratio of 8, and temperature of 333 K. Under optimal conditions, about 99% of Cu was leached after 180 min. The shrinking core model was used to analyze the kinetics of the Cu leaching process, and the results showed that the surface chemical reaction governs this process. The activation energy of the leaching reaction, calculated using Two-Point form of the Arrhenius equation, was 10.852 kJ mol−1. Full article
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19 pages, 12133 KiB  
Article
Experimental and Analytical Investigation of the Re-Melting Effect in the Manufacturing of 316L by Direct Energy Deposition (DED) Method
by Harun Kahya, Hakan Gurun and Gokhan Kucukturk
Metals 2023, 13(6), 1144; https://doi.org/10.3390/met13061144 - 20 Jun 2023
Cited by 1 | Viewed by 1624
Abstract
In this study, the effects of the laser power (2000 W, 2250 W, 2500 W), scanning speed (0.6, 0.8, 1 m/min), and powder feed rate (10, 12.5, 15 g/min) on material structures and their mechanical properties were investigated in the production of 316L [...] Read more.
In this study, the effects of the laser power (2000 W, 2250 W, 2500 W), scanning speed (0.6, 0.8, 1 m/min), and powder feed rate (10, 12.5, 15 g/min) on material structures and their mechanical properties were investigated in the production of 316L stainless steels through Direct Energy Deposition (DED). In addition, changes in the microstructure caused by the re-melting process were also investigated. Optimized process parameters were modeled using the CFD software (FLOW 3D V3.0). In order to see the effects on the density and mechanical properties, the sample production was repeated as a build and by applying the re-melting process between the layers. When the energy density and powder feed rate are considered together, it has been determined that the deposition rate increases in direct proportion to the energy density and tends to decrease inversely with the powder feed rate. When the experimental and analysis results of the single clad height are compared, it is seen that the values obtained are very approximate. It has been observed that the most important parameters affecting the formation of porosity are the energy density and powder feed density. Re-melting slightly affects the microstructure of the material and causes grain growth. Changes in the impact strength of the re-melted samples were observed depending on the energy density. Full article
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13 pages, 4424 KiB  
Article
Microstructure Refinement and Work-Hardening Behaviors of NiAl Alloy Prepared by Combustion Synthesis and Hot Pressing Technique
by Jia-Yu Hu, Shuang Zhang, Long-Jiang Zhang, Fan Peng, Hai-Long Zhao and Feng Qiu
Metals 2023, 13(6), 1143; https://doi.org/10.3390/met13061143 - 19 Jun 2023
Cited by 1 | Viewed by 1462
Abstract
Most methods used to synthesize and prepare NiAl intermetallics and their alloys have the disadvantages of complexity and high cost. In this paper, the NiAl alloy was prepared by a Combustion Synthesis and Hot Pressing (CSHP) technique under rapid solidification. The grain size [...] Read more.
Most methods used to synthesize and prepare NiAl intermetallics and their alloys have the disadvantages of complexity and high cost. In this paper, the NiAl alloy was prepared by a Combustion Synthesis and Hot Pressing (CSHP) technique under rapid solidification. The grain size of the NiAl alloy is significantly refined to 60–80 μm, which reduces the stress concentration during deformation and improves the fracture strength and fracture hardness. Moreover, the large internal stress and greater amount of dislocations in the as-cast microstructure are produced by their formation under pressure due to the fast cooling rate in the solidification process. The high dislocation density strengthens the NiAl alloy, giving it higher strength, hardness, and work-hardening ability. The high compression properties are also present in the NiAl intermetallics at room temperature, in which the fracture strength is around 1005 MPa and the fracture strain reaches 21.6%. The compressive fracture strength at room temperature is higher than that of the pure NiAl alloy prepared by the Hot-Pressing-Aided Exothermic Synthesis (HPES, about 632 MPa), while it is slightly lower than that of pure NiAl alloy treated by HPES and Hot Isostatic Pressing (HIP, 1050 MPa). The fracture strain is significantly higher than that of the NiAl alloy prepared by other methods. This study can provide guidance for the successful preparation of the NiAl alloy with high strength and toughness. Full article
(This article belongs to the Special Issue Advanced Intermetallic Alloys and Intermetallics)
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29 pages, 9011 KiB  
Review
Ultra-Low Cycle Fatigue Life Prediction Model—A Review
by Yali Xu, Xin Li, Yanjuan Zhang and Jianwei Yang
Metals 2023, 13(6), 1142; https://doi.org/10.3390/met13061142 - 19 Jun 2023
Cited by 4 | Viewed by 2517
Abstract
This article is a review of models for predicting ultra-low cycle fatigue life. In the article, the life prediction models are divided into three types: (1) microscopic ductile fracture models based on cavity growth and cavity merger; (2) fracture models based on porous [...] Read more.
This article is a review of models for predicting ultra-low cycle fatigue life. In the article, the life prediction models are divided into three types: (1) microscopic ductile fracture models based on cavity growth and cavity merger; (2) fracture models based on porous plasticity; and (3) ductile fracture models based on continuum damage mechanics. Furthermore, the article provides a critical assessment of the current state of research on ultra-low cycle fatigue life prediction models, highlighting the limitations and challenges faced by each model type. Ultimately, this review aims to provide a comprehensive overview of the different models available for predicting ultra-low cycle fatigue life and to guide future research in this important area of materials science and engineering. Full article
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2 pages, 166 KiB  
Editorial
Heat Treatment of Iron- and Aluminum-Based Alloys
by Silvia Barella
Metals 2023, 13(6), 1141; https://doi.org/10.3390/met13061141 - 19 Jun 2023
Viewed by 927
Abstract
Iron- and aluminum-based alloys are the most commonly used metallic materials for engineering applications [...] Full article
(This article belongs to the Special Issue Heat Treatment of Iron- and Aluminum-Based Alloys)
45 pages, 3943 KiB  
Review
The Paramagnetic Meissner Effect (PME) in Metallic Superconductors
by Michael Rudolf Koblischka, Ladislav Půst, Crosby-Soon Chang, Thomas Hauet and Anjela Koblischka-Veneva
Metals 2023, 13(6), 1140; https://doi.org/10.3390/met13061140 - 19 Jun 2023
Cited by 2 | Viewed by 2392
Abstract
The experimental data in the literature concerning the Paramagnetic Meissner Effect (PME) or also called Wohlleben effect are reviewed with the emphasis on the PME exhibited by metallic, s-wave superconductors. The PME was observed in field-cool cooling (FC-C) and field-cool warming (FC-W) [...] Read more.
The experimental data in the literature concerning the Paramagnetic Meissner Effect (PME) or also called Wohlleben effect are reviewed with the emphasis on the PME exhibited by metallic, s-wave superconductors. The PME was observed in field-cool cooling (FC-C) and field-cool warming (FC-W) m(T)-measurements on Al, Nb, Pb, Ta, in compounds such as, e.g., NbSe2, In-Sn, ZrB12, and others, and also in MgB2, the metallic superconductor with the highest transition temperature. Furthermore, samples with different shapes such as crystals, polycrystals, thin films, bi- and multilayers, nanocomposites, nanowires, mesoscopic objects, and porous materials exhibited the PME. The characteristic features of the PME, found mainly in Nb disks, such as the characteristic temperatures T1 and Tp and the apparative details of the various magnetic measurement techniques applied to observe the PME, are discussed. We also show that PME can be observed with the magnetic field applied parallel and perpendicular to the sample surface, that PME can be removed by abrading the sample surface, and that PME can be introduced or enhanced by irradiation processes. The PME can be observed as well in magnetization loops (MHLs, m(H)) in a narrow temperature window Tp<Tc, which enables the construction of a phase diagram for a superconducting sample exhibiting the PME. We found that the Nb disks still exhibit the PME after more than 20 years, and we present the efforts of magnetic imaging techniques (scanning SQUID microscopy, magneto-optics, diamond nitrogen-vacancy (NV)-center magnetometry, and low-energy muon spin spectroscopy, (LE-μSR)). Various attempts to explain PME behavior are discussed in detail. In particular, magnetic measurements of mesoscopic Al disks brought out important details employing the models of a giant vortex state and flux compression. Thus, we consider these approaches and demagnetization effects as the base to understand the formation of the paramagnetic signals in most of the materials investigated. New developments and novel directions for further experimental and theoretical analysis are also outlined. Full article
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11 pages, 4087 KiB  
Article
A 4340 Steel with Superior Strength and Toughness Achieved by Heterostructure via Intercritical Quenching and Tempering
by Yi Sang, Guosheng Sun and Jizi Liu
Metals 2023, 13(6), 1139; https://doi.org/10.3390/met13061139 - 19 Jun 2023
Cited by 5 | Viewed by 2206
Abstract
The conventional 4340 steel was used after quenching and tempering, strengthened by the classical pearlitic structure where cementite particles are dispersed through the ferrite matrix. In the present study, a heterostructure microstructure consisting of micro-sized residual ferrite zones and pearlitic zones was introduced [...] Read more.
The conventional 4340 steel was used after quenching and tempering, strengthened by the classical pearlitic structure where cementite particles are dispersed through the ferrite matrix. In the present study, a heterostructure microstructure consisting of micro-sized residual ferrite zones and pearlitic zones was introduced by an optimized process of intercritical quenching and tempering, resulting in a steel with higher strength and better toughness. The pearlite steel has a tensile strength of 1233 MPa, yield strength of 1156 MPa, and toughness of 121.5 MJ/m3. Compared with the pearlite steel, the tensile strength and yield strength of the heterostructure steel have been improved by 67 MPa and 74 MPa, respectively, while the toughness has been increased by 52.5 MJ/m3. In this heterostructure, the micro-sized ferrite bulks serve as the soft zones surrounded by the hard zones of the pearlite structure to achieve a remarkable work-hardening capacity. Statistical analysis shows that the heterostructure has the best hetero-deformation-induced (HDI) hardening capability when the residual ferrite bulk contributes ~31% by volume fraction, and the quenching temperature is around 780 °C. This study opens new ways of thinking about the strengthening and toughening mechanism of heat treatment of medium carbon steels. Full article
(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys)
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23 pages, 25742 KiB  
Article
Optimizing the Gating System for Rapid Investment Casting of Shape Memory Alloys: Computational Numerical Analysis for Defect Minimization in a Simple-Cubic Cell Structure
by Carlos E. S. Albuquerque, Paulo C. S. Silva, Estephanie N. D. Grassi, Carlos J. De Araujo, João M. P. Q. Delgado and Antonio G. B. Lima
Metals 2023, 13(6), 1138; https://doi.org/10.3390/met13061138 - 19 Jun 2023
Cited by 2 | Viewed by 1351
Abstract
With the aid of virtual prototyping and casting numerical simulation, this work presents the optimization of an injection system used in a non-traditional investment casting process that applies perpendicular centrifugal force to inject the molten metal into refractory plaster molds. In this study, [...] Read more.
With the aid of virtual prototyping and casting numerical simulation, this work presents the optimization of an injection system used in a non-traditional investment casting process that applies perpendicular centrifugal force to inject the molten metal into refractory plaster molds. In this study, advanced techniques of simulation and production of complex geometries in Computer-Aided Design CAD (Computer-Aided Design) are used in the design of the casting system of a miniaturized simple-cubic cell structure. The cast part has a complex shape profile and needs a high surface finish with strict dimensional tolerance. The alloy used to fill the mold is an aluminum bronze shape memory alloy (SMA). CAD was used to model the part and the proposed models for casting optimization. ProCAST software was used for the numerical simulation of the casting process. Experimental parameters were used as input data for the numerical simulation. The simulation results were analyzed focusing on the identification of defects in the Cu–Al–Mn SMA simple-cubic structures. Different feeding systems have been designed to eliminate the identified defects. Concerning the molten recirculation, the optimal nozzle model has a truncated cone profile, with a larger radius of 6.5 mm, a smaller radius of 2.0 mm and a height of 8.0 mm (called here model 3). Experimental observations from cast SMA parts agree with the simulated results of the optimized nozzle model 3. In addition to the elimination of alloy recirculation with the nozzle optimization in this work, the shrinkage porosity at the upper base of the part was eliminated with the addition of a compensation volume close to the region where porosity is more intense. By exploring the possibilities offered by commercial software, the work contributes to advance the knowledge and application of the non-traditional investment casting process, highlighting its advantages and potential applications. Full article
(This article belongs to the Special Issue Modeling and Simulation of Solidification in Alloys)
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15 pages, 6664 KiB  
Article
The Corrosion and Wear-Corrosion of the Iron-Base Amorphous Coating Prepared by the HVOF Spraying
by Pin-Hsun Liao, Jing-Wei Jian and Leu-Wen Tsay
Metals 2023, 13(6), 1137; https://doi.org/10.3390/met13061137 - 18 Jun 2023
Cited by 2 | Viewed by 1359
Abstract
In this work, the corrosion behaviors of an iron-based amorphous coating produced by high-velocity oxy-fuel (HVOF) spraying were investigated. Potentiodynamic and potentiostatic polarization and corrosion pin-on-ring (corrosion-wear) tests were conducted to evaluate the corrosive properties of the coating as compared with the 316L [...] Read more.
In this work, the corrosion behaviors of an iron-based amorphous coating produced by high-velocity oxy-fuel (HVOF) spraying were investigated. Potentiodynamic and potentiostatic polarization and corrosion pin-on-ring (corrosion-wear) tests were conducted to evaluate the corrosive properties of the coating as compared with the 316L substrate. The corrosion behaviors of the 316L substrate and coated sample were tested in 3.5 wt.% NaCl, 1 M HCl, and 0.5 M H2SO4 solutions. In the 3.5 wt.% NaCl and 1 M HCl solutions, the corrosion resistance of the coating was a little inferior or equivalent to that of the 316L substrate after potentiodynamic polarization tests. In the 0.5 M H2SO4 solution, the two tested samples exhibited wide passivated zones in the polarization curves. In such a mild acid, the corrosion resistance of the 316 substrate was superior to that of the amorphous coating, possibly due to the presence of defects in the coating. After potentiodynamic polarization tests, the linkage of initial fine pits into large, deep pores was seen in the corroded 316L substrate. By contrast, extensive corrosion along with preferentially corroded defective sites was seen in the coating. Moreover, the coating exhibited a much higher resistance to corrosion-wear, or low weight loss, in 3.5 wt.% NaCl solution. After the corrosion-wear tests, deep furrows were present in the 316L substrate, whereas a rubbed smooth surface and a corroded zone were seen in the coating. The greater weight loss of the 316L substrate confirmed its poor resistance to corrosion-wear relative to the amorphous coating in 3.5 wt.% NaCl solution. Full article
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13 pages, 3831 KiB  
Article
The Influence of Two-Jet Gas Shielding Parameters on the Structure and Microhardness of Steel 45 Joints during Consumable Electrode Welding
by Dmitry A. Chinakhov and Dmitry Pavlovich Il’yashchenko
Metals 2023, 13(6), 1136; https://doi.org/10.3390/met13061136 - 18 Jun 2023
Cited by 1 | Viewed by 1157
Abstract
The paper presents the study results of the parameters influence of arc welding with a consumable electrode with two-jet gas shielding in CO2 on the structure and microhardness of high-strength steel 45 welded joints with slotted edges. Controlling the dynamic impact of [...] Read more.
The paper presents the study results of the parameters influence of arc welding with a consumable electrode with two-jet gas shielding in CO2 on the structure and microhardness of high-strength steel 45 welded joints with slotted edges. Controlling the dynamic impact of the internal shielding gas jet on the processes in the welding zone changes the heat and mass transfer processes in the welding zone and results in the intensive mixing of the molten electrode metal with the base metal in the weld pool. The results of the studies determined the dynamic effect of the active shielding gas jet on the structure and microhardness of multilayered steel 45 welded joints with slotted edges using the method of full factorial experiment, developed dependences of chemical elements (carbon, silicon, manganese) content in the weld metal of multilayered steel 45 welded joints on the controlled parameters of the welding mode (Q, Iw, U). Due to uneven heat introduction into each of the welded plates during edge slotting, the asymmetric distribution of microhardness in the cross sections of welded joints relative to the weld axis indicates some differences in the structure and properties of the heat-affected zone (HAZ) and the weld. According to the results of the studies, consumable electrode arc welding with two-jet gas shielding provides faster distribution and equalization of heat on the product surface and reduces its instantaneous overheating, which improves the structural phase state of the welded joint made of steel 45 and reduces the microhardness gradient in the HAZ. An increase in the heat input of welding (a simultaneous increase in the welding current and voltage of the welding arc) leads to a decrease and smoothing of the microhardness peak in the HAZ. Full article
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15 pages, 5116 KiB  
Article
Vanadium–Titanium Magnetite Concentrate, Calcium–Magnesium Composite Roasting and Sulfuric Acid Leaching for Vanadium Extraction from Pellets
by Zhonghui Peng, Zhixiang Wang, Zhongchen Han, Yongze Zhu, Yang Li and Keqiang Xie
Metals 2023, 13(6), 1135; https://doi.org/10.3390/met13061135 - 16 Jun 2023
Cited by 1 | Viewed by 1318
Abstract
This paper investigated a pellet ore production process in which vanadium was extracted from vanadium and titanium magnetite concentrates using sulfuric acid leaching. Calcium and magnesium were added to the iron ore concentrate during pellet production to produce calcium vanadate and magnesium vanadate [...] Read more.
This paper investigated a pellet ore production process in which vanadium was extracted from vanadium and titanium magnetite concentrates using sulfuric acid leaching. Calcium and magnesium were added to the iron ore concentrate during pellet production to produce calcium vanadate and magnesium vanadate after roasting. The pellets were leached with sulfuric acid solution to extract V5+. The resulting pellets had a compressive strength of 3375 N after primary roasting, a good pellet morphology after acid leaching, and simple liquid–solid separation. Under the optimal experimental conditions, the vanadium leaching rate in the pellets reached 77.86%, while the iron leaching rate was only 1.17%. The pellets did not fragment, which was an improvement upon existing vanadium extraction methods. The strength of the pellets after vanadium extraction decreased to 563 N, but after secondary roasting, the compressive strength of the pellets reached 2578 N, which was suitable for blast furnace ironmaking. The roasting and acid leaching experiments showed that the vanadium extraction process resulted in suitable pellet properties. The use of low compound additives can effectively improve the leaching effect, while avoiding the previous problems of too many additives, pellet iron grade reduction, or the pursuit of high vanadium extraction rate pellet breakage and serious high secondary use process costs. Full article
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16 pages, 5986 KiB  
Article
Mechanical Fracture of Aluminium Alloy (AA 2024-T4), Used in the Manufacture of a Bioproducts Plant
by Luis Fabian Urrego, Olimpo García-Beltrán, Nelson Arzola and Oscar Araque
Metals 2023, 13(6), 1134; https://doi.org/10.3390/met13061134 - 16 Jun 2023
Cited by 3 | Viewed by 1626
Abstract
Aluminium alloy (AA2024-T4) is a material commonly used in the aerospace industry, where it forms part of the fuselage of aircraft and spacecraft thanks to its good machinability and strength/weight ratio. These characteristics allowed it to be applied in the construction of the [...] Read more.
Aluminium alloy (AA2024-T4) is a material commonly used in the aerospace industry, where it forms part of the fuselage of aircraft and spacecraft thanks to its good machinability and strength/weight ratio. These characteristics allowed it to be applied in the construction of the structure of a pilot plant to produce biological extracts and nano-encapsulated bioproducts for the phytosanitary control of diseases associated with microorganisms in crops of Theobroma cacao L. (Cacao). The mechanical design of the bolted support joints for this structure implies knowing the performance under fatigue conditions of the AA2024-T4 material since the use of bolts entails the placement of circular stress concentrators in the AA2024-T4 sheet. The geometric correction constant (Y) is a dimensionless numerical scalar used to correct the stress intensity factor (SIF) at the crack tip during propagation. This factor allows the stress concentration to be modified as a function of the specimen dimensions. In this work, four compact tension specimens were modeled in AA2024-T4, and each one was modified by introducing a second circular stress concentrator varying its size between 15 mm, 20 mm, 25 mm, and 30 mm, respectively. Applying a cyclic load of 1000N, a load ratio R=-1 and a computational model with tetrahedral elements, it was determined that the highest SIF corresponds to the specimen with a 30 mm concentrator with a value close to 460 MPa.mm0.5. Where the crack propagation had a maximum length of 53 mm. Using these simulation data, it was possible to process each one and obtain a mathematical model that calculates the geometric correction constant (Y). The calculated data using the new model was shown to have a direct relationship with the behavior obtained from the simulation. Full article
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15 pages, 2794 KiB  
Article
Notch-Stress S–N Curves for Welded Aluminum-Alloy Components Subjected to Bending
by Tomislav Matić, Nenad Vulić, Dražen Kustura and Ivan Peko
Metals 2023, 13(6), 1133; https://doi.org/10.3390/met13061133 - 16 Jun 2023
Viewed by 1083
Abstract
Fatigue analysis of aluminum-alloy welded joints based on the linear elastic notch-stress approach is presented in this paper. The International Institute of Welding proposes two variants of the approach, one for thick joints, i.e., joints with a plate thickness of 5 mm or [...] Read more.
Fatigue analysis of aluminum-alloy welded joints based on the linear elastic notch-stress approach is presented in this paper. The International Institute of Welding proposes two variants of the approach, one for thick joints, i.e., joints with a plate thickness of 5 mm or more, with a reference radius rref = 1 mm, using the FAT71 notch-stress design curve, and one for thin joints, i.e., joints with a plate thickness of less than 5 mm, with a reference radius rref = 0.05 mm, using the FAT180 notch-stress design curve. In this work, the feasibility of the proposed S–N curves, obtained mainly by fatigue tests on axially loaded joints, was investigated for 4 mm thick joints subjected to bending. The fatigue analysis was performed for two types of joints: a joint with longitudinal fillet-welded attachment and a joint with round sheet fillet-welded attachment. It was shown that a more accurate estimation of the fatigue life of 4 mm thick aluminum joints loaded in bending can be obtained using the FAT71 notch-stress design curve. Full article
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15 pages, 4913 KiB  
Article
Effect of Residual Stress on Mode-I Stress Intensity Factor: A Quantitative Evaluation and a Suggestion of an Estimating Equation
by Thanh Tuan Nguyen, Van Son Pham, Hoang Anh Tran, Duc Huy Nguyen, Thu Huong Nguyen and Hong Bo Dinh
Metals 2023, 13(6), 1132; https://doi.org/10.3390/met13061132 - 16 Jun 2023
Cited by 2 | Viewed by 1319
Abstract
An extensive literature review was conducted primarily to develop a comprehensive understanding of the quantitative behavior of residual stress (RS) distribution in weld joints. Based on prior data, various levels of the peak RS and distribution profiles were applied to a finite element [...] Read more.
An extensive literature review was conducted primarily to develop a comprehensive understanding of the quantitative behavior of residual stress (RS) distribution in weld joints. Based on prior data, various levels of the peak RS and distribution profiles were applied to a finite element analyses (FEA) model as an initial loading to evaluate the effect of RS on the Mode-I stress intensity factor (SIF), KI. The RS was not found to have a significant effect on the SIF values when the peak RS was less than 300 MPa. The enhanced effect of RS on the KI values was found to be more pronounced at a lower crack ratio, while the analytical form of the RS distribution had a minor effect. The effective boundary corrections function, FResidual, was derived under the effect of RS for 1T CT specimen for various crack geometries of the crack ratio, (a/W) of 0.2, 0.40, 0.50, 0.60, and 0.75, and with peak RS varying from 100 MPa to 600 MPa. The obtained effective function of KI can be employed to quantitatively evaluate the effect of RS on the fatigue performance of welded joints. Full article
(This article belongs to the Section Welding and Joining)
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13 pages, 4263 KiB  
Article
Flow Field Study of Large Bottom-Blown Lead Smelting Furnace with Numerical Simulation
by Wenlong Xi, Liping Niu and Jinbo Song
Metals 2023, 13(6), 1131; https://doi.org/10.3390/met13061131 - 16 Jun 2023
Cited by 1 | Viewed by 1201
Abstract
In this paper, a large bottom-blown lead smelting furnace is studied by numerical simulation, the flow characteristics of different planes, monitoring points and molten pool regions are analysed, and a formula is established to predict the velocity distribution of molten pool in the [...] Read more.
In this paper, a large bottom-blown lead smelting furnace is studied by numerical simulation, the flow characteristics of different planes, monitoring points and molten pool regions are analysed, and a formula is established to predict the velocity distribution of molten pool in the bottom-blown furnace. The results show that the flow between two adjacent oxygen lances will influence each other and effectively reduce the existence of a low-velocity region. The high-velocity region at the liquid surface is mainly distributed above the bubble molten pool reaction region (BMRR), and the velocity is transmitted to the upper/lower sides. The wall shear stress is mainly distributed at the bottom and on the walls on both sides of the BMRR. The pre-stabilisation time of a bottom-blown furnace is 2 s, and the unstable state existing in the local region will not have a great influence on the overall flow field in the furnace. The distribution of the bubble plume and the high-velocity region overlaps under the free liquid surface, and their boundaries are basically consistent. The fitting effect of the velocity cumulative percentage curve and each point is very good. Full article
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21 pages, 4296 KiB  
Article
Multi-Response Optimization of Additively Manufactured Ti6Al4V Component Using Grey Relational Analysis Coupled with Entropy Weights
by Khaled N. Alqahtani, Abdulmajeed Dabwan, Emad Hashiem Abualsauod, Saqib Anwar, Ali M. Al-Samhan and Husam Kaid
Metals 2023, 13(6), 1130; https://doi.org/10.3390/met13061130 - 16 Jun 2023
Cited by 2 | Viewed by 1486
Abstract
Due to its near-net-shape manufacturing and ability to treat challenging-to-manufacture materials such as titanium alloys, Additive manufacturing (AM) is growing in popularity. However, due to the poor surface quality of AM components, finishing processes such as machining are required. One of the most [...] Read more.
Due to its near-net-shape manufacturing and ability to treat challenging-to-manufacture materials such as titanium alloys, Additive manufacturing (AM) is growing in popularity. However, due to the poor surface quality of AM components, finishing processes such as machining are required. One of the most difficult aspects of finishing AM components is the fact that even when using the same machining parameters, the surface roughness can vary significantly depending on the orientation of the part. In this study, electron beam melting (EBM) Ti6Al4V parts are subjected to the finishing (milling) process in three potential orientations relative to the direction of the tool feed. The impact of the feed rate, radial depth of cut, and cutting speed on the surface roughness and cutting force of the Ti6Al4V EBM part is studied while taking the orientations of the EBM components into consideration. It is found that the machined surface changes in noticeable ways with respect to orientation. A factorial design is used for the experiments, and analysis of variance (ANOVA) is used to evaluate the results. Furthermore, the grey relational analysis (GRA) method coupled with entropy weights is utilized to determine the optimal process variables for machining a Ti6Al4V EBM component. The results show that the feed rate has the greatest impact on the multi-response optimization, followed by the cutting speed, faces, and radial depth of cut. Full article
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16 pages, 7096 KiB  
Article
Experimental and Numerical Investigation of Hot Extruded Inconel 718
by Stefano Bacchetti, Michele A. Coppola, Francesco De Bona, Alex Lanzutti, Pierpaolo Miotti, Enrico Salvati and Francesco Sordetti
Metals 2023, 13(6), 1129; https://doi.org/10.3390/met13061129 - 16 Jun 2023
Viewed by 1549
Abstract
Inconel 718 is a widely used superalloy, due to its unique corrosion resistance and mechanical strength properties at very high temperatures. Hot metal extrusion is the most widely used forming technique, if the manufacturing of slender components is required. As the current scientific [...] Read more.
Inconel 718 is a widely used superalloy, due to its unique corrosion resistance and mechanical strength properties at very high temperatures. Hot metal extrusion is the most widely used forming technique, if the manufacturing of slender components is required. As the current scientific literature does not comprehensively cover the fundamental aspects related to the process–structure relationships, in the present work, a combined numerical and experimental approach is employed. A finite element (FE) model was established to answer three key questions: (1) predicting the required extrusion force at different extrusion speeds; (2) evaluating the influence of the main processing parameters on the formation of surface cracks using the normalized Cockcroft Latham’s (nCL) damage criterion; and (3) quantitatively assessing the amount of recrystallized microstructure through Avrami’s equation. For the sake of modeling validation, several experimental investigations were carried out under different processing conditions. Particularly, it was found that the higher the initial temperature of the billet, the lower the extrusion force, although a trade-off must be sought to avoid the formation of surface cracks occurring at excessive temperatures, while limiting the required extrusion payload. The extrusion speed also plays a relevant role. Similarly to the role of the temperature, an optimal extrusion speed value must be identified to minimize the possibility of surface crack formation (high speeds) and to minimize the melting of intergranular niobium carbides (low speeds). Full article
(This article belongs to the Special Issue Material Modeling in Multiphysics Simulation)
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18 pages, 15331 KiB  
Article
Processability of A6061 Aluminum Alloy Using Laser Powder Bed Fusion by In Situ Synthesis of Grain Refiners
by Michele Rosito, Matteo Vanzetti, Elisa Padovano, Flavia Gili, Roberta Sampieri, Federica Bondioli and Claudio Francesco Badini
Metals 2023, 13(6), 1128; https://doi.org/10.3390/met13061128 - 16 Jun 2023
Cited by 4 | Viewed by 2245
Abstract
Despite the increasing interest in laser powder bed fusion (LPBF), only a few cast aluminum alloys are available for this process. This study focuses on improving the LPBF processability of the A6061 alloy, which is challenging due to its wide solidification range, the [...] Read more.
Despite the increasing interest in laser powder bed fusion (LPBF), only a few cast aluminum alloys are available for this process. This study focuses on improving the LPBF processability of the A6061 alloy, which is challenging due to its wide solidification range, the dendritic columnar grain growth, and consequent solidification cracking. To address these issues, in situ-synthesized grain refiners can be used to induce equiaxial grain growth and prevent crack formation. A6061 RAM2 powder—a mixture of A6061, Ti, and B4C—was characterized and processed using a low-power LPBF machine to create an in situ particle-reinforced metal matrix composite. Parameter optimization was performed to evaluate the effect of their variation on the printability of the alloy. Microstructural characterization of the samples revealed that the complete reaction and the synthesis of the ceramic reinforcement did not occur. However, TiAl3 was synthesized during the process and promoted a partial grain refinement, leading to the formation of equiaxial grains and preventing the formation of solidification cracks. The tensile tests carried out on the optimized samples exhibit superior mechanical properties compared to those of A6061 processed through LPBF. Full article
(This article belongs to the Section Additive Manufacturing)
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11 pages, 14820 KiB  
Article
Research on the Formation, Microstructure, and Properties of 304 Stainless Steel AC-DC Hybrid TIG Welding
by Ying Ye, Bairu Yang, Yonghui Yang, Zihan Pan, Chao Chen and Xinlong Zhang
Metals 2023, 13(6), 1127; https://doi.org/10.3390/met13061127 - 16 Jun 2023
Cited by 1 | Viewed by 1308
Abstract
In this work, a new welding method, AC-DC hybrid TIG welding, is used to weld 304 stainless steel. Research on the formation, microstructure, and properties of 304 stainless-steel welded joints are studied by using optical microscope and microhardness. The results show that the [...] Read more.
In this work, a new welding method, AC-DC hybrid TIG welding, is used to weld 304 stainless steel. Research on the formation, microstructure, and properties of 304 stainless-steel welded joints are studied by using optical microscope and microhardness. The results show that the weld with AC/DC hybrid welding is a fish-scale pattern, and the density of the fish-scale pattern increases with the increase of AC proportion. Both the weld penetration and the ratio of weld penetration to weld width are the highest when AC accounts for 30%. At this point, the weld penetration is 0.83 mm larger than DC mode, an increase of 93.26%, and the ratio of weld penetration to weld width is 1.6, which is 76.19% higher than DC mode. When the proportion of AC is increased, the microstructure of the weld is equiaxed or columnar, and the microstructure of the heat-affected zone is ferrite in the form of lath. The hardness of the weld is greater than that of the base metal, and the hardness of the heat-affected zone is the lowest. The microhardness distribution of the weld with AC 50% is the most uniform. When AC accounts for 20% and 30%, the average weld hardness is the highest, which are 196.7 HV and 198.1 HV, respectively. Full article
(This article belongs to the Special Issue Corrosion Protection for Metallic Materials)
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13 pages, 12675 KiB  
Article
The Effects of Post-Welding Heat Treatment on the Cryogenic Absorbed Energy of High Manganese Steel Weld Metal
by Seungho Baek, Minha Park, Je In Lee and Sung-Hwan Kim
Metals 2023, 13(6), 1126; https://doi.org/10.3390/met13061126 - 15 Jun 2023
Cited by 1 | Viewed by 1736
Abstract
In this study, a post-weld heat treatment (PWHT) was proposed at high temperatures of 600 °C, 750 °C, and 900 °C for 30 min to significantly improve the impact absorbed energy of high manganese steel weld metal. Electron backscatter diffraction (EBSD), electron probe [...] Read more.
In this study, a post-weld heat treatment (PWHT) was proposed at high temperatures of 600 °C, 750 °C, and 900 °C for 30 min to significantly improve the impact absorbed energy of high manganese steel weld metal. Electron backscatter diffraction (EBSD), electron probe microanalysis (EPMA), and high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) were employed to characterize the production and study the deformation mechanisms in the high manganese steel weld metal. The impact absorbed energy is divided into crack initiation energy and crack propagation energy, which are divided by the value of Pmax. The cryogenic impact absorbed energy was 81 J. After PWHT at 600 °C, 750 °C, and 900 °C, it was 75 J, 69 J, and 88 J, respectively. The impact absorbed energies did not follow a proportional relationship with the PWHT temperatures. The increase in impact absorbed energy can be attributed to the narrowing of the dendritic region, which blocks the crack propagation path and efficiently prevents crack propagation. Conversely, the decrease in impact absorbed energy can be attributed to the presence of 100-nm-sized (Cr, Mn)23C6-type carbides at the grain boundaries, which facilitate crack propagation. Full article
(This article belongs to the Special Issue Grain Refinement and Mechanical Properties of Cast Alloys)
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15 pages, 3242 KiB  
Article
Processing of Al/SiC/Gr Hybrid Composite on EDM by Different Electrode Materials Using RSM-COPRAS Approach
by Adel T. Abbas, Neeraj Sharma, Zeyad A. Alsuhaibani, Vishal S. Sharma, Mahmoud S. Soliman and Rakesh Chandmal Sharma
Metals 2023, 13(6), 1125; https://doi.org/10.3390/met13061125 - 15 Jun 2023
Cited by 12 | Viewed by 1420
Abstract
The present research used the stir-casting method to develop an Al-based composite. The developed composite exhibited challenges while being processed on conventional machining. Thus, a non-traditional machining process was opted to process the composite. The machining variables selected for the current research were [...] Read more.
The present research used the stir-casting method to develop an Al-based composite. The developed composite exhibited challenges while being processed on conventional machining. Thus, a non-traditional machining process was opted to process the composite. The machining variables selected for the current research were the pulse off time (Toff), pulse on time (Ton), servo voltage (SV), current (I), and tool electrode. Three tool electrodes (SS-304, copper, and brass) were used to process the developed composite (Al/SiC/Gr). The experimental plan was designed using response surface methodology (RSM). The output responses recorded for the analysis were the material removal rate (MRR) and tool wear rate (TWR). The obtained data was optimized using complex proportional assessment (COPRAS) and machine learning methods. The optimized settings predicted by the RSM–COPRAS method were Ton: 60 µs; Toff: 60 µs; SV: 7 V; I: 12 A; and tool: brass. The maximum MRR and TWR at the suggested settings were 1.11 g/s and 0.0114 g/s, respectively. A morphological investigation of the machined surface and tool surface was conducted with scanning electron microscopy. The morphological examination of the surface (machined) presented the presence of cracks, lumps, etc. Full article
(This article belongs to the Special Issue Modelling and Simulation in Metal Cutting and Machining Process)
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13 pages, 7801 KiB  
Article
Effect of B and N Content and Austenitization Temperature on the Tensile and Impact Properties of Modified 9Cr-1Mo Steels
by Ravindran Rejeesh, Rakesh Kumar Barik, Rahul Mitra, Andrii Kostryzhev, Chitta R. Das, Shaju K. Albert and Debalay Chakrabarti
Metals 2023, 13(6), 1124; https://doi.org/10.3390/met13061124 - 15 Jun 2023
Cited by 1 | Viewed by 1199
Abstract
The present study investigates the relative effect of B and N concentrations and the austenitization temperature on the microstructure and mechanical properties (tensile and Charpy impact) of modified 9Cr-1Mo (P91) steels. Initially, a B-free P91 steel (with 500 ppm N) and four different [...] Read more.
The present study investigates the relative effect of B and N concentrations and the austenitization temperature on the microstructure and mechanical properties (tensile and Charpy impact) of modified 9Cr-1Mo (P91) steels. Initially, a B-free P91 steel (with 500 ppm N) and four different B-containing steels (25–100 ppm) with varying N concentrations (20–108 ppm) were hot-rolled, normalized from different austenitization temperatures (1000–1100 °C/1 h) and finally tempered at 760 °C for 1 h. A Charpy impact test shows that the ductile–brittle transition temperature (DBTT) of all the B-added steels decreases with an increase in the austenitization temperature, where the 100 ppm B steel offers the lowest DBTT (−85 °C). Similarly, the strength increases with the increase in the austenitization temperature (1100 °C), with a slight drop in ductility. The influence of precipitates on the microstructure and mechanical properties is explained considering the B enrichment at the precipitates and the thermodynamic stability of the precipitates. The 100 ppm B steel (containing the maximum B and minimum N), normalized from 1100 °C austenitization, shows the best combination of tensile and Charpy impact properties, owing to the effective dissolution of coarse M23C6 and MX precipitates during the normalization treatment and the formation of fine B-rich (Fe,Cr)23(B,C)6 precipitates during the subsequent tempering. Full article
(This article belongs to the Section Metal Casting, Forming and Heat Treatment)
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18 pages, 5011 KiB  
Article
Differential Analysis and Prediction of Planar Shape at the Head and Tail Ends of Medium-Thickness Plate Rolling
by Shiyu Yang, Hongmin Liu and Dongcheng Wang
Metals 2023, 13(6), 1123; https://doi.org/10.3390/met13061123 - 15 Jun 2023
Cited by 1 | Viewed by 1009
Abstract
This paper aims to improve planar shape prediction accuracy in the rolling process of medium and thick plates. We present a model based on the strip method that addresses limitations in predicting planar shape variations at the head and tail ends of rolled [...] Read more.
This paper aims to improve planar shape prediction accuracy in the rolling process of medium and thick plates. We present a model based on the strip method that addresses limitations in predicting planar shape variations at the head and tail ends of rolled pieces. By analysing the rolling process, we introduce the concept of an imaginary strip longitudinal length difference to represent planar shape characteristics effectively. By analysing the change in metal shape in the rolling deformation zone, the calculation formula for metal volume in the deformation zone is derived. This establishes a relationship between the longitudinal length difference at the rolled piece ends and the metal volume in the deformation zone. The prediction of plane shape difference between the end and the head of medium and medium-thickness plate is realized. The experimental results confirm the feasibility and effectiveness of the proposed method. Full article
(This article belongs to the Special Issue Advances in Modeling and Simulation in Metal Forming)
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24 pages, 5742 KiB  
Article
A Novel Electrode Front-End Face Design to Improve Geometric Accuracy in Electrical Discharge Machining Process
by Shih-Ming Wang, Jin-Kai Peng, Hariyanto Gunawan, Ren-Qi Tu and Shean-Juinn Chiou
Metals 2023, 13(6), 1122; https://doi.org/10.3390/met13061122 - 15 Jun 2023
Cited by 1 | Viewed by 1223
Abstract
Electrical discharge machining (EDM) is one of the important machining processes to produce mold components. When using the EDM process, surface quality, processing time, accuracy, and electrode cost must be considered. The electrode wear is the main factor that causes error on the [...] Read more.
Electrical discharge machining (EDM) is one of the important machining processes to produce mold components. When using the EDM process, surface quality, processing time, accuracy, and electrode cost must be considered. The electrode wear is the main factor that causes error on the geometric accuracy, especially the workpiece corner. Therefore, this study proposes a novel electrode design to improve the geometric accuracy for the EDM process. Firstly, the effect of discharge current, electrode diameter, and depth of cut on the electrode wear and workpiece corner were investigated. Multiple regression and analysis of variant were used to analyze the experiment data. The electrode end-face design with compensation rule and algorithm was established based on the data analysis and error value. Furthermore, a compensated electrode end-face design system with human machine interface, which has a procedure guiding function, was developed. The system can design the electrode end-face for minimizing workpiece corner error and improve geometric accuracy. Finally, cutting experiments were conducted to verify the proposed method, and the results show that the proposed method can effectively enhance the geometric accuracy by around 22~37%. Full article
(This article belongs to the Special Issue Green Manufacturing for Metallic Materials)
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14 pages, 5811 KiB  
Article
Phase Transformation Crystallography in Pipeline HSLA Steel after TMCP
by Mikhail L. Lobanov, Maria A. Zorina, Maxim S. Karabanalov, Nikolay V. Urtsev and Andrey A. Redikultsev
Metals 2023, 13(6), 1121; https://doi.org/10.3390/met13061121 - 15 Jun 2023
Cited by 1 | Viewed by 1535
Abstract
Thermo-mechanical controlled processing (TMCP) is employed to obtain the required level of mechanical properties of contemporary high-strength low-alloy (HSLA) steel plates utilized for gas and oil pipeline production. The strength, deformation behavior and resistance to the formation and propagation of running fractures of [...] Read more.
Thermo-mechanical controlled processing (TMCP) is employed to obtain the required level of mechanical properties of contemporary high-strength low-alloy (HSLA) steel plates utilized for gas and oil pipeline production. The strength, deformation behavior and resistance to the formation and propagation of running fractures of the pipeline steel are mainly determined by its microstructure and crystallographic texture. These are formed as a result of austenite deformation and consequent γ→α-transformation. This present study analyses the crystallographic regularities of the structural and textural state formation in a steel plate that has been industrially produced by means of TMCP. The values of the mechanical properties that have been measured in different directions demonstrate the significance of the crystallographic texture in the deformation and failure of steel products. An electron backscatter diffraction (EBSD) method and crystallographic analysis were utilized to establish the connection between the main texture components of the deformed austenite and α-phase orientations. This paper demonstrates that the crystallographic texture that is formed due to a multipath γ→α-transformation results from the α-phase nucleation on the special boundaries between grains with γ-phase orientations. The analysis of the spectra of the α-γ-interface boundary angle deviations from the Kurdjumov–Sachs (K–S), Nishiyama–Wassermann (N–W), and Greninger–Troiano (G–T) orientation relationships (ORs) allows to suggest that the observed austenite particles represent a secondary austenite (not retained) that precipitates at intercrystalline α-phase boundaries and correspond to the ORs with regard to only one adjacent crystallite. Full article
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13 pages, 18946 KiB  
Article
Evolution of Microstructures, Texture and Mechanical Properties of Al-Mg-Si-Cu Alloy under Different Welding Speeds during Friction Stir Welding
by Zhang Luo, Youping Sun, Wangzhen Li, Jiangmei He, Guojian Luo and Huashen Liu
Metals 2023, 13(6), 1120; https://doi.org/10.3390/met13061120 - 14 Jun 2023
Cited by 1 | Viewed by 1174
Abstract
The effects of different welding speeds on the microstructures and mechanical properties of Al-0.75Mg-0.75Si-0.8Cu alloys were investigated using optical metallographic microscopy (OM), X-ray diffraction (XRD) analysis, an ETM105D electronic universal testing machine and field emission electron microscopy (SEM). The results reveal that during [...] Read more.
The effects of different welding speeds on the microstructures and mechanical properties of Al-0.75Mg-0.75Si-0.8Cu alloys were investigated using optical metallographic microscopy (OM), X-ray diffraction (XRD) analysis, an ETM105D electronic universal testing machine and field emission electron microscopy (SEM). The results reveal that during the friction stir welding process, the welded joint forms the base material (BM), heat-affected zone (HAZ), thermomechanically affected zone (TMAZ) and nugget zone (NZ), under the action of shear force and friction heat. The textures present in the BM are mainly C ({001}<100>) recrystallised cubic texture and P({110}<112>) recrystallised texture, Goss (G) texture, brass (B) texture and {112}<110> rotating copper texture. The organisation of the NZ undergoes dynamic recrystallisation, forming fine isometric crystals with large angular grain boundaries, accounting for more than 75% of the total. The geometrically necessary dislocations (GNDs) in the NZ grow as the welding speed rises. Moreover, {111}<110> and {111}<110> shearing textures, {001}<110> recrystallisation textures and fibre textures are mainly present in NZs. The average grain size in the NZ was the smallest, and the mechanical properties were the best at a welding speed of 125 mm/min. The grain size and the tensile strength and elongation of the NZ were 2.945 µm, 200.7 MPa and 12.7% for the joint at a welding speed of 125 mm/min, respectively. Full article
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14 pages, 9329 KiB  
Article
Microstructure and First Hydrogenation Properties of Ti30V60Mn(10−x)Crx (x = 0, 3.3, 6.6, 10) + 4 wt.% Zr
by Chourouk Kefi and Jacques Huot
Metals 2023, 13(6), 1119; https://doi.org/10.3390/met13061119 - 14 Jun 2023
Cited by 2 | Viewed by 1287
Abstract
In this paper, we studied the effect of the Cr/Mn ratio on the microstructure, crystal structure and hydrogen absorption properties of the quaternary alloys of compositions Ti30V60Mn(10−x)Crx (x = 0, 3.3, 6.6 and [...] Read more.
In this paper, we studied the effect of the Cr/Mn ratio on the microstructure, crystal structure and hydrogen absorption properties of the quaternary alloys of compositions Ti30V60Mn(10−x)Crx (x = 0, 3.3, 6.6 and 10) + 4 wt.% Zr. The addition of Hf instead of Zr was also investigated. We found that all alloys are single-phase BCC (Body Centred Cubic) but with regions of high concentration of Zr (or Hf). The first hydrogenation at room temperature under 2 MPa of hydrogen happens quickly without any incubation time. The Ti30V60Mn3.3Cr6.6 + 4 wt.% Zr alloy showed the fastest kinetics and highest hydrogen absorption (3.8 wt.%). For this composition, replacing Zr with Hf made the first hydrogenation slower and reduced the capacity to 3.4 wt.%. No activation was observed for the same alloy without additives. As the alloy without additives did not absorb hydrogen at all, it means that the presence of these high concentrations of Zr (or Hf) is essential for quick first hydrogenation. Full article
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