Metals

20 pages, 3370 KiB

Open AccessArticle

Effect of Atomic Ordering on Phase Stability and Elastic Properties of Pd-Ag Alloys

by Xiaoli Chen, Guangxiong Luo, Yuxuan Cao and Chaoping Liang

Metals 2024, 14(9), 1017; https://doi.org/10.3390/met14091017 (registering DOI) - 5 Sep 2024

Abstract

Palladium (Pd) and its alloys, renowned for their good corrosion resistance, catalytic efficiency, and hydrogen affinity, find extensive use in various industrial applications. However, the susceptibility of pure Pd to hydrogen embrittlement necessitates alloying strategies such as Pd-Ag systems. This study investigates the [...] Read more.

Palladium (Pd) and its alloys, renowned for their good corrosion resistance, catalytic efficiency, and hydrogen affinity, find extensive use in various industrial applications. However, the susceptibility of pure Pd to hydrogen embrittlement necessitates alloying strategies such as Pd-Ag systems. This study investigates the impact of the ordering on the phase stability and elastic properties of Pd-Ag alloys through first-principles calculations. We explore a series of ordered phase structures alongside random solid solutions using Special Quasirandom Structures (SQSs), evaluating their thermodynamic stability and elastic properties. Our findings indicate the possible existence of stable ordered L1₂ Pd₃Ag and PdAg₃ and L1₁ PdAg phases, which are thought to exist only in Cu-Pt alloys. An analysis of the elastic constants and anisotropy indices underscores some pronounced directional dependencies in the mechanical responses between the random solid-solution and ordered phases. This suggests that the ordered phases not only are thermodynamically and mechanically more stable than solid-solution phases, but also display a decrease in anisotropy indices. The results provide a deeper understanding of the atomic behavior of Pd-Ag alloys, and shed light on the design of multiphase Pd-Ag alloys to improve their mechanical properties. Full article

19 pages, 13652 KiB

Open AccessArticle

Research on Microstructural Evolution Behavior of Ni-Based Single-Crystal Alloy with Re Based on Non-Linear Ultrasonic Lamb Wave and Molecular Dynamics Method

by Ben Li, Yilin Zhang, Hongyan Zhou and Xuewu Li

Metals 2024, 14(9), 1016; https://doi.org/10.3390/met14091016 (registering DOI) - 5 Sep 2024

Abstract

Interface dislocation networks have a great influence on the mechanical properties of the new Ni-based single-crystal alloy (NSC) containing Re, but it is difficult to find out the structural evolution behaviors at the micro-level. Thus, molecular dynamics (MD) simulation is used to analyze [...] Read more.

Interface dislocation networks have a great influence on the mechanical properties of the new Ni-based single-crystal alloy (NSC) containing Re, but it is difficult to find out the structural evolution behaviors at the micro-level. Thus, molecular dynamics (MD) simulation is used to analyze the atomic potential energy change and dislocation evolution mechanism, and non-linear characteristic parameters are used to analyze the microstructure evolution of NSC. First, a new model of Ni-Al-Re that is closer to the real properties of the material is established using the MD method according to the optimal volume ratio of matrix phase to precipitate phase. Then, the MD models of NSC with different contents of Re are calculated and analyzed under compressive and tensile loads. The results show that with an increase in Re atoms, the atomic potential energy at the interface dislocation networks is reduced; thus, the stability of the system is enhanced, and the hindrance of the interface dislocation networks to the dislocation movement of the matrix phase is strengthened. At the same time, the number of HCP structures and OISs formed by the destruction of the intact FCC structures also decreases. In the non-linear ultrasonic experiment, with the increase in Re atoms, the non-linear enhancement of the microstructure of the NSC leads to an increase in the corresponding non-linear characteristic parameters. Accordingly, the microstructural evolution behaviors of the phase interface of the new NSC can be effectively explored using the combination of MD simulation and non-linear ultrasonic experimentation. The results of this study lay a foundation for the subsequent research of the microscopic defects of NSCs by using ultrasonic phased-array technology. Full article

(This article belongs to the Special Issue Characterization and Processing Technology of Superalloys)

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18 pages, 8676 KiB

Open AccessArticle

Effects of In Situ TiB₂ on the Microstructural Evolution, Mechanical Properties, and Friction Behavior of the Al-Si-Cu Alloys Processed by Laser Powder-Bed Fusion

by Zhongxue He, Jianying Wang, Mengzhen Zhu, Tao Wen, Feipeng Yang, Shouxun Ji, Jianming Zheng, Ling Shan and Hailin Yang

Metals 2024, 14(9), 1015; https://doi.org/10.3390/met14091015 - 5 Sep 2024

Abstract

In the present study, the densification behavior, microstructural evolution, mechanical properties, and friction behavior of a TiB₂/Al8SiCu composite and Al8SiCu alloy manufactured by laser powder-bed fusion (PBF-LB) were systematically investigated. The results confirm that the addition of in situ TiB₂ [...] Read more.

In the present study, the densification behavior, microstructural evolution, mechanical properties, and friction behavior of a TiB₂/Al8SiCu composite and Al8SiCu alloy manufactured by laser powder-bed fusion (PBF-LB) were systematically investigated. The results confirm that the addition of in situ TiB₂ particles into Al8SiCu alloys reduce the volumetric energy density required for a high-density TiB₂/Al8SiCu composite. The TiB₂ particles promoted a transformation of columnar to equiaxed crystals and the formation of high-angle grain boundaries. The grains on the vertical direction of the PBF-LBed TiB₂/Al8SiCu composite were much finer than those of the PBF-LBed Al8SiCu alloy. The addition of TiB₂ promoted the grain refinement of the Al8SiCu alloy, of which the average grain size decreased from 15.31 μm to 7.34 μm. The yield strength (YS), ultimate tensile strength (UTS), and elongation (El) of the PBF-LBed Al8SiCu alloy were 296 ± 6 MPa, 517 ± 6 MPa, and 11.7 ± 1.0%, respectively. The PBF-LBed TiB₂/Al8SiCu composite achieved a balance between strength and ductility with a yield strength of 328 ± 8 MPa, an ultimate tensile strength of 541 ± 3 MPa, and an elongation of 9.1 ± 0.7%. The increase in strength mainly resulted from grain boundary strengthening, dislocation strengthening, load-bearing strengthening, solid-solution strengthening, and Orowan strengthening, of which the dislocation strengthening and Orowan strengthening were critical. The enhanced hardness associated with the grain refinement and the formation of the in situ TiB₂ particles also led to an enhanced tribological performance, of which reductions in the average friction coefficient from 0.655 to 0.580 and wear rate from 1.76 × 10⁻³ mm³/Nm to 1.38 × 10⁻³ mm³/Nm were found. Full article

(This article belongs to the Special Issue Recent Developments of Non-ferrous Alloys: Processing, Microstructure and Properties (2nd Edition))

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14 pages, 9244 KiB

Open AccessArticle

Effect of Zn Addition on the Microstructure and Discharge Performance of Mg-Al-Mn-Ca Alloys for Magnesium-Air Batteries

by Yiwei Gong, Kezheng Wei, Wenlong Jiang, Chongchen Xiang, Hanlin Ding and Zijian Wang

Metals 2024, 14(9), 1014; https://doi.org/10.3390/met14091014 - 5 Sep 2024

Abstract

This study explores the effects of Zn addition through micro-alloying on the microstructure and discharge performance of Mg-Al-Mn-Ca alloy anodes for magnesium-air batteries. The results show that the second-phase particles (d > 1 μm) in a Mg-Al-Mn-Ca alloy promote dynamic recrystallization (DRX) via [...] Read more.

This study explores the effects of Zn addition through micro-alloying on the microstructure and discharge performance of Mg-Al-Mn-Ca alloy anodes for magnesium-air batteries. The results show that the second-phase particles (d > 1 μm) in a Mg-Al-Mn-Ca alloy promote dynamic recrystallization (DRX) via particle-stimulated nucleation (PSN), resulting in a uniform equiaxed grain structure and fiber texture. In contrast, Zn and Ca co-segregation in a Mg-Al-Mn-Ca-Zn alloy facilitates continuous dynamic recrystallization (CDRX) and, combined with the PSN mechanism, forms a unique structure where three types of grains with different grain boundary densities coexist. The addition of Zn and Ca effectively reduces the c/a axis ratio, promoting texture homogenization. The Mg-Al-Mn-Ca alloy exhibits rough discharge surfaces due to simultaneous discharge at numerous grain boundaries and severe hydrogen evolution corrosion from micro-galvanic effects, inducing the chunk effect (CE). Conversely, the structure where three types of grains with different grain boundary densities coexist in the Mg-Al-Mn-Ca-Zn alloy promotes discharge product detachment through stress cracking, achieving uniform discharge and significantly enhancing discharge performance. The uniform texture reduces hydrogen evolution corrosion, improving anode utilization. This study demonstrates that controlling the microstructure, particularly grain boundary density and grain texture, enables the development of high-performance Mg-Al-Mn-Ca-Zn alloy anodes, especially at higher current densities, offering a new strategy for designing efficient magnesium alloy anode materials. Full article

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19 pages, 17830 KiB

Open AccessArticle

Influence of Partial Er Substitution for Sc on the Microstructure, Mechanical Properties and Corrosion Resistance of Short-Processed Al-4.7Mg-0.6Mn-0.3Zr-0.3Sc Sheets

by Guangxi Lu, Yabo Liang, Cong Xu, Wenfei Rao, Yaodong Xue, Longfei Li, Li Zhang and Shaokang Guan

Metals 2024, 14(9), 1013; https://doi.org/10.3390/met14091013 - 5 Sep 2024

Abstract

Standard AA5083 (ZSE000), AA5083 modified with 0.3 wt.% Zr and 0.3wt.% Sc (ZSE330) and AA5083 modified with 0.3 wt.% Zr, 0.2wt.% Sc and 0.1wt.%Er(ZSE321) sheets were fabricated through a short process (including a simulated twin-belt continuous casting, subsequent direct rolling, intermediate annealing, cold [...] Read more.

Standard AA5083 (ZSE000), AA5083 modified with 0.3 wt.% Zr and 0.3wt.% Sc (ZSE330) and AA5083 modified with 0.3 wt.% Zr, 0.2wt.% Sc and 0.1wt.%Er(ZSE321) sheets were fabricated through a short process (including a simulated twin-belt continuous casting, subsequent direct rolling, intermediate annealing, cold rolling and stress-relief annealing) to systematically investigate the influence of partially substituting Er for Sc on the microstructure, mechanical properties and corrosion resistance of short-processed Al-4.7Mg-0.6Mn-0.3Zr-0.3Sc sheets. The results show that ZSE321 presents the optimal tensile properties (UTS: 541 MPa; 0.2%PS: 469 MPa and EF:7.7%) among the three experimental sheets. This is attributed to significant grain refinement, the inhibition of the recrystallization and promotion on the precipitation of Al₃(Sc, Zr, Er) nanoparticles. Furthermore, the corrosion properties of the experimental sheets were also explored in this study, and the short-processed ZSE321 sheet presents the optimum corrosion resistance. Full article

(This article belongs to the Special Issue Special and Short Processes of Aluminum Alloys)

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20 pages, 16114 KiB

Open AccessArticle

Investigation on the Solidification Structure of Q355 in 475 mm Extra-Thick Slabs Adopting Cellular Automaton-Finite Element Model

by Kezai Yu, Minglin Wang, Haihan Fan, Zhonghua Zhan, Zixiang Ren and Lijun Xu

Metals 2024, 14(9), 1012; https://doi.org/10.3390/met14091012 - 4 Sep 2024

Viewed by 179

Abstract

The solidification structure characteristics are decisive for the production of extra-thick slabs. This study developed a solidification heat transfer model and a cellular automaton–finite element coupled model to investigate the solidification behavior and structure characteristics of a 475 mm extra-thick slab. The models [...] Read more.

The solidification structure characteristics are decisive for the production of extra-thick slabs. This study developed a solidification heat transfer model and a cellular automaton–finite element coupled model to investigate the solidification behavior and structure characteristics of a 475 mm extra-thick slab. The models were applied under various continuous casting process parameters and different alloy element content. The simulation results reveal that casting speed has the most significant effect on the solidification behavior of extra-thick slabs, surpassing the impact of specific water flow and superheat. The solidification structure characteristics of the 475 mm extra-thick slabs were investigated under various conditions. The findings indicate that at higher casting speeds and superheats, the average grain size increases and the grain number decreases. The average grain size initially decreases and then increases with the rise in specific water flow, reaching its minimum at approximately 0.17 L·kg⁻¹. Additionally, the average grain radius first decreases and then slightly increases with an increase in carbon content, achieving the minimum value of about 0.17% carbon. Compared with carbon and manganese, silicon has a greater impact on the solidification structure of ultra-thick slabs, and a moderate increase in silicon content can effectively refine the grain size. This study provides a theoretical foundation for understanding the changes in solidification structure characteristics and optimizing continuous casting process parameters for 475 mm extra-thick slabs. Full article

(This article belongs to the Special Issue Green Super-Clean Steels)

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16 pages, 5092 KiB

Open AccessArticle

Material Strength Optimization of Dissimilar MIG Welding between Carbon and Stainless Steels

by Hoang Van Huong, Thanh Tan Nguyen, Van-Thuc Nguyen and Van Thanh Tien Nguyen

Metals 2024, 14(9), 1011; https://doi.org/10.3390/met14091011 - 4 Sep 2024

Viewed by 213

Abstract

This study examines the effects of stick-out, welding current, welding speed, and voltage on the mechanical characteristics and microstructure of MIG welding on SUS 304 stainless steel and S20C steel. The Taguchi method was used to maximize the experiment’s outcomes. Fine columnar dendrites [...] Read more.

This study examines the effects of stick-out, welding current, welding speed, and voltage on the mechanical characteristics and microstructure of MIG welding on SUS 304 stainless steel and S20C steel. The Taguchi method was used to maximize the experiment’s outcomes. Fine columnar dendrites formed at fusion sites, and δ-ferrite phases with dark lines and shapes accumulated between the fusion line and the austenite phases. A welding current of 110 A, voltage of 15 V, welding speed of 500 mm/min, and stick-out of 12 mm were the optimal settings for the ultimate tensile strength (UTS). The UTS value confirmation was 469.4 MPa, which agrees with the estimated value determined using the Taguchi technique. The tensile test revealed that welding current had a far greater impact on mechanical qualities than welding voltage, speed, and stick-out distance. The ideal welding parameters for flexural strength were as follows: stick-out of 12 mm, arc voltage of 15 V, welding speed of 450 mm/min, and welding current of 110 amp. The Taguchi method is useful, as evidenced by the validation of the flexure strength of 1937.45 MPa, which is much greater than the other samples. The impact of the thermal annealing process on the mechanical characteristics of the dissimilar weld joints could be the subject of future research. The investigation results may offer more insightful information about the dissimilar welding field. Full article

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15 pages, 19974 KiB

Open AccessArticle

Effect of Heat Treatment on the Microstructure and Corrosion Resistance of Al_0.75CoCr_1.25FeNi High-Entropy Alloys

by Jianyang Han, Huan Zhang, Hongtao Yuan, Xiaoru Zhuo, Xiang Cai and Yanxin Qiao

Metals 2024, 14(9), 1010; https://doi.org/10.3390/met14091010 - 4 Sep 2024

Viewed by 163

Abstract

In this work, heat treatment of three different temperatures (600 °C, 800 °C, and 1000 °C) was applied to as-cast Al_0.75CoCr_1.25FeNi high-entropy alloys (HEAs) to investigate the influence of heat treatment on their corrosion properties. Open circuit potential (OCP) [...] Read more.

In this work, heat treatment of three different temperatures (600 °C, 800 °C, and 1000 °C) was applied to as-cast Al_0.75CoCr_1.25FeNi high-entropy alloys (HEAs) to investigate the influence of heat treatment on their corrosion properties. Open circuit potential (OCP) and cyclic polarization tests reveal that the 1000 °C heat-treated HEA possesses excellent corrosion resistance, as indicated by the low corrosion tendency and corrosion current density. Electrochemical impedance spectroscopy (EIS) and potentiostatic polarization analyses imply the presence of a superior passive film on the 1000 °C heat-treated HEA. X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the passive film formed on the 1000 °C heat-treated HEA during potentiostatic polarization tests is most corrosion-resistant since it possesses the highest ratio of Al₂O₃/Al(OH)₃ and Cr₂O₃/Cr(OH)₃. Full article

(This article belongs to the Special Issue Advances in the Design and Behavior Analysis of High-Strength Steels)

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17 pages, 3601 KiB

Open AccessArticle

Design of Point Charge Models for Divalent Metal Cations Targeting Quantum Mechanical Ion–Water Dimer Interactions

by Yongguang Zhang, Binghan Wu, Chenyi Lu and Haiyang Zhang

Metals 2024, 14(9), 1009; https://doi.org/10.3390/met14091009 - 3 Sep 2024

Viewed by 304

Abstract

Divalent metal cations are of vital importance in biochemistry and materials science, and their structural and thermodynamic properties in aqueous solution have often been used as targets for the development of ion models. This study presented a strategy for designing nonbonded point charge [...] Read more.

Divalent metal cations are of vital importance in biochemistry and materials science, and their structural and thermodynamic properties in aqueous solution have often been used as targets for the development of ion models. This study presented a strategy for designing nonbonded point charge models of divalent metal cations (Mg²⁺ and Ca²⁺) and Cl⁻ by targeting quantum mechanics (QM)-based ion–water dimer interactions. The designed models offered an accurate representation of ion–water interactions in the gas phase and showed reasonable performance for non-targeted properties in aqueous solutions, such as the ion–water oxygen distance (IOD), coordination number (CN), and density and viscosity of MgCl₂ and CaCl₂ solutions at low concentrations. Our metal cation models yielded considerable overestimates of the hydration free energies (HFEs) of the ions, whereas the Cl⁻ model displayed good performance. Together with the overestimated density and viscosity of the salt solutions, these results indicated the necessity of re-optimizing ion–ion interactions and/or including polarization effects in the design of ion models. The designed Mg²⁺ model was capable of maintaining the crystal metal-binding networks during MD simulation of a metalloprotein, indicating great potential for biomolecular simulations. This work highlighted the potential of QM-based ion models to advance the study of metal ion interactions in biological and material systems. Full article

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11 pages, 4002 KiB

Open AccessArticle

Microstructure Evolution and Tensile Properties of Medium Manganese Steel Heat Treated by Two-Step Annealing

by Tao Kang, Zhanyu Zhan, Changcheng Wang, Zhengzhi Zhao, Juhua Liang and Lele Yao

Metals 2024, 14(9), 1008; https://doi.org/10.3390/met14091008 - 3 Sep 2024

Viewed by 210

Abstract

In this paper, the nucleation and growth of austenite are controlled through a two-step annealing process to achieve multi-scale distribution and content increase of retained austenite in low manganese series medium-Mn steel. Combining SEM, EBSD, AES, and other experimental equipment, the evolution rules [...] Read more.

In this paper, the nucleation and growth of austenite are controlled through a two-step annealing process to achieve multi-scale distribution and content increase of retained austenite in low manganese series medium-Mn steel. Combining SEM, EBSD, AES, and other experimental equipment, the evolution rules of the microstructure, properties, and element distribution behavior of the test steel during the annealing process are studied. Compared with one-step annealing, the two-step annealing significantly broadens the size distribution range of retained austenite. In the first step, after annealing at a higher intercritical temperature (760 °C), the ferrite and the M/A island are obtained, completing the initial partition of Mn and the refinement of microstructures. During the second step of annealing (720 °C), the primary Mn-rich martensite region provides higher nucleation driving force and finer dispersed nucleation sites, promoting the nucleation and growth of reverse transformation austenite. At the same time, the metastable-retained austenite formed after the first step of annealing continues to grow through interface movement. Furthermore, a high proportion (23.4%) of retained austenite with multi-scale distribution is formed in the final microstructure, and the product of strength and elongation increased from 21.8 GPa·% by the one-step annealing process to 30.1 GPa·%. Full article

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14 pages, 6219 KiB

Open AccessArticle

Effect of Fe Element and Ultrasonic Vibration on the Microstructure and Mechanical Properties of the Cu-TiB₂ Composites

by Siruo Zhang, Guanglong Li, Cunhu Duan, Yingdong Qu, Min Cheng and Shulin Dong

Metals 2024, 14(9), 1007; https://doi.org/10.3390/met14091007 - 2 Sep 2024

Viewed by 276

Abstract

Cu-(Fe-Ti)-TiB₂ composites were prepared by in situ reaction and vacuum casting with and without ultrasonic vibration. The evolution of the microstructure and mechanical properties of the composite with the variation in Fe element was analyzed. The import of Fe elements could purify [...] Read more.

Cu-(Fe-Ti)-TiB₂ composites were prepared by in situ reaction and vacuum casting with and without ultrasonic vibration. The evolution of the microstructure and mechanical properties of the composite with the variation in Fe element was analyzed. The import of Fe elements could purify the matrix after in situ reaction and the formation of a nanoprecipitated phase, thus improving the strength of Cu-Fe-Ti-TiB₂ composites. Meanwhile, compared with the traditional casting process, the Cu-Fe-Ti-TiB₂ composites with ultrasonic vibration treatment exhibit uniform TiB₂ particle distribution and better properties. The tensile strength and uniform elongation of the composite with a Fe content of 0.7 wt.% reached 511 MPa and 6.02%, increasing by 14.3% and 318% compared to the unalloyed composite, respectively. The tensile strength and uniform elongation of Cu-0.7Fe-Ti-TiB₂ composite with ultrasonic vibration treatment increased to 533 MPa and 7.16%, respectively. The TiB₂ microscale particles and Fe₂Ti nanoscale precipitates with uniform distribution effectively impeded dislocation movement and recrystallization, which improved the tensile strength and stability at elevated temperatures. Full article

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16 pages, 8638 KiB

Open AccessArticle

The Effect of Ultrafast Heating on the Microstructure and Mechanical Properties of the 2.2 GPa Grade Hot Forming Steel

by Mai Wang, Jiang Chang, Hongyi Wu, Zhenli Mi, Yanxin Wu and Qi Zhang

Metals 2024, 14(9), 1006; https://doi.org/10.3390/met14091006 - 2 Sep 2024

Viewed by 434

Abstract

The aim of the present work is to evaluate the effect of ultrafast heating on the microstructure and mechanical properties of hot forming steel. The initial microstructure utilized in this study was a cold-rolled microstructure, and the test steel was heated to full [...] Read more.

The aim of the present work is to evaluate the effect of ultrafast heating on the microstructure and mechanical properties of hot forming steel. The initial microstructure utilized in this study was a cold-rolled microstructure, and the test steel was heated to full austenitization at a rate of 200 °C/s, followed by water quenching. It was observed that the ultrafast heating process significantly refines both the prior austenite grains and martensite laths while inheriting high-density dislocations from the initial cold-rolled microstructure. Consequently, the coupling mechanism between dislocation strengthening and grain refinement strengthening remarkably enhanced both the yield strength and ultimate tensile strength of the test steel. Eventually, the yield strength of the hot forming steel reached 1524 MPa, along with an ultimate tensile strength of 2221 MPa and uniform elongation of 5.2%. Full article

(This article belongs to the Special Issue Service Performance and Analysis of Advanced Metallic Materials)

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15 pages, 4289 KiB

Open AccessArticle

Fluid Dynamics Studies on Bottom Liquid Detachment from a Rising Bubble Crossing a Liquid–Liquid Interface

by Xiangfeng Cheng, Gele Qing, Zhixing Zhao and Baojun Zhao

Metals 2024, 14(9), 1005; https://doi.org/10.3390/met14091005 - 2 Sep 2024

Viewed by 293

Abstract

The detachment regimes and corresponding detachment height of lower liquid from a coated bubble during the bubble passage through an immiscible liquid–liquid interface were studied. High-speed imaging techniques were used to visualize the lower liquid detachment from a rising bubble near the interface. [...] Read more.

The detachment regimes and corresponding detachment height of lower liquid from a coated bubble during the bubble passage through an immiscible liquid–liquid interface were studied. High-speed imaging techniques were used to visualize the lower liquid detachment from a rising bubble near the interface. Analysis of industrial slag samples by a scanning electron microscope (SEM) was also carried out. The results indicate that the detachment height of lower liquid from a rising bubble showed a distinct correlation to penetration regimes. Bubble size and a fluid’s physical properties exerted a significant influence on the detachment height of the lower liquid. The detachment height for medium bubbles (Weber number: 4~4.5; Bond number: 2.5~7.5) varied significantly with increasing bubble size, which contributes to the lower liquid entrainment in the upper phase due, significantly, to the higher detachment height and large entrainment volume. The maximum detachment height for large bubbles is limited to approximately 100 mm due to the early detachment with the liquid column at the interface though large bubbles transporting a larger volume of lower liquid into the upper phase. Full article

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

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19 pages, 3682 KiB

Open AccessArticle

Mechanism of Anodic Dissolution of Tungsten in Sulfate–Fluoride Solutions

by Martin Bojinov, Yoanna Penkova, Iva Betova and Vasil Karastoyanov

Metals 2024, 14(9), 1004; https://doi.org/10.3390/met14091004 - 2 Sep 2024

Viewed by 222

Abstract

Thin passive films on tungsten play an important role during the surface levelling of the metal for various applications and during the initial stages of electrochemical synthesis of thick, nanoporous layers that perform well as photo-absorbers and photo-catalysts for light-assisted water splitting. In [...] Read more.

Thin passive films on tungsten play an important role during the surface levelling of the metal for various applications and during the initial stages of electrochemical synthesis of thick, nanoporous layers that perform well as photo-absorbers and photo-catalysts for light-assisted water splitting. In the present work, the passivation of tungsten featuring metal dissolution and thin oxide film formation is studied by a combination of in situ electrochemical (voltammetry and impedance spectroscopy) and spectro-electrochemical methods coupled with ex situ surface oxide characterization by XPS. Voltametric and impedance data are successfully reproduced by a kinetic model featuring oxide growth and dissolution coupled with the recombination of point defects, as well as a multistep tungsten dissolution reaction at the oxide/electrolyte interface. The model is in good agreement with the spectro-electrochemical data on soluble oxidation products and the surface chemical composition of the passive oxide. Full article

(This article belongs to the Section Corrosion and Protection)

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13 pages, 3464 KiB

Open AccessArticle

Influence of Ceramic Size and Morphology on Interface Bonding Properties of TWIP Steel Matrix Composites Produced by Lost-Foam Casting

by Guojin Sun, Xiaoming Liu, Zhenggui Li and Qi Wang

Metals 2024, 14(9), 1003; https://doi.org/10.3390/met14091003 - 2 Sep 2024

Viewed by 289

Abstract

This study investigated the fabrication and characterization of large ceramic-reinforced TWIP (twinning-induced plasticity) steel matrix composites using the lost-foam casting technique. Various ceramic shapes and sizes, including blocky, flaky, rod-like, and granular forms, were evaluated for their suitability as reinforcement materials. The study [...] Read more.

This study investigated the fabrication and characterization of large ceramic-reinforced TWIP (twinning-induced plasticity) steel matrix composites using the lost-foam casting technique. Various ceramic shapes and sizes, including blocky, flaky, rod-like, and granular forms, were evaluated for their suitability as reinforcement materials. The study found that rod-like and granular ceramics exhibited superior structural integrity and formed strong interfacial bonds with the TWIP steel matrix compared to blocky and flaky ceramics, which suffered from cracking and fragmentation. Detailed microstructural analysis using scanning electron microscopy (SEM) and industrial computed tomography (CT) revealed the mechanisms influencing the composite formation. The results demonstrated that rod-like and granular ceramics are better for reinforcing TWIP steel composites, providing excellent mechanical stability and enhanced performance. This work contributes to the development of advanced composite structures with potential applications in industries requiring high-strength and durable materials. Full article

(This article belongs to the Special Issue Mechanical and Functional Properties of Refractory Metal-Ceramic Composites Used in Advanced High-Temperature Applications)

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19 pages, 8526 KiB

Open AccessArticle

Engineering Corrosion Resistance in Magnesium Alloys for Biomedical Applications: A Synergy of Zn/Ca Atomic Ratio and Texture-Based Approach

by Manisha Behera, Rajashekhara Shabadi and Cosmin Gruescu

Metals 2024, 14(9), 1002; https://doi.org/10.3390/met14091002 - 2 Sep 2024

Viewed by 298

Abstract

Magnesium (Mg) and Magnesium-Zinc-Calcium alloys present a compelling option for biodegradable implant materials. Utilizing Vacuum Induction Casting, Mg–2.5Zn-xCa (with x = 0.3, 0.5, 0.9, 1.15 wt%) alloys were fabricated and subjected to hot-rolling for thermo-mechanical processing. The hot-rolled Mg–2.5Zn-0.3Ca alloy exhibits the lowest [...] Read more.

Magnesium (Mg) and Magnesium-Zinc-Calcium alloys present a compelling option for biodegradable implant materials. Utilizing Vacuum Induction Casting, Mg–2.5Zn-xCa (with x = 0.3, 0.5, 0.9, 1.15 wt%) alloys were fabricated and subjected to hot-rolling for thermo-mechanical processing. The hot-rolled Mg–2.5Zn-0.3Ca alloy exhibits the lowest corrosion rate along with the highest basal texture. Increasing the Zn/Ca atomic ratio intensifies the basal texture and enhances corrosion resistance. Elevated Zn concentration improves corrosion resistance via Ca₂Mg₆Zn₃ phase formation, while increased Ca content diminishes corrosion resistance due to the Mg₂Ca phase. Advancement of this alloy is poised to extend Mg alloy use in innovative biomedical bone implants. Full article

(This article belongs to the Special Issue Advanced Biomedical Materials (2nd Edition))

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22 pages, 13523 KiB

Open AccessArticle

The Impact of Welding Parameters on the Welding Strength of High Borosilicate Glass and Aluminum Alloy

by Changjun Chen, Jian Tang, Min Zhang and Wei Zhang

Metals 2024, 14(9), 1001; https://doi.org/10.3390/met14091001 - 2 Sep 2024

Viewed by 395

Abstract

This study adopts a new surface pretreatment method, Laser Surface Remelting (LSR). This experiment aims to establish a set of laser welding process parameters suitable for aluminum alloy and glass under this specific pretreatment. This experiment explores the impact of laser welding parameters [...] Read more.

This study adopts a new surface pretreatment method, Laser Surface Remelting (LSR). This experiment aims to establish a set of laser welding process parameters suitable for aluminum alloy and glass under this specific pretreatment. This experiment explores the impact of laser welding parameters on the welding strength between high borosilicate glass and aluminum alloy. The study specifically investigates the effects of four process parameters: defocus amount, laser power, frequency, and pulse width on the welding outcome. The results indicate that the welding quality between the aluminum alloy and glass reaches its optimum when the defocus amount is zero (i.e., when the laser converges at the interface between the glass and the metal) and the laser welding parameters are set to a power of 250 W, a welding speed of 1 mm/s, a welding frequency of 10 Hz, and a pulse width of 2.5 ms. The experiment also analyzes the fracture morphology under different parameters, summarizing the locations and causes of fractures, and establishing the relationship between the fracture location and the welding strength. Full article

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12 pages, 1769 KiB

Open AccessReview

Recent Progress on Atmospheric Corrosion of Field-Exposed Magnesium Alloys

by Mengqi Wang, Lihui Yang, Hao Liu, Xiutong Wang, Yantao Li and Yanliang Huang

Metals 2024, 14(9), 1000; https://doi.org/10.3390/met14091000 - 2 Sep 2024

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Abstract

It is well known that the poor corrosion resistance of magnesium alloys is a key factor limiting their application. Field exposure is the most reliable means to evaluate the atmospheric corrosion performance of magnesium alloys. This article reviews the field exposure corrosion behavior [...] Read more.

It is well known that the poor corrosion resistance of magnesium alloys is a key factor limiting their application. Field exposure is the most reliable means to evaluate the atmospheric corrosion performance of magnesium alloys. This article reviews the field exposure corrosion behavior of magnesium alloys in typical atmospheric environments (including the marine atmosphere, industrial atmosphere, etc.) in recent years. According to the literature review, it was found that there are significant regional differences in the atmospheric corrosion behavior of magnesium alloys, which is the result of the coupling of multiple factors in the atmospheric environment. By investigating the corrosion rate and corrosion products of different types of magnesium alloys in different environments, the corrosion mechanism of magnesium alloys in different environments was summarized. Specifically, environmental parameters such as atmospheric temperature, relative humidity, CO₂, and chloride ion deposition rates in the marine atmospheric environment can affect the corrosion behavior of magnesium alloys. The corrosion of magnesium alloys in different industrial atmospheric environments is mainly affected by atmospheric temperature and relative humidity, as well as atmospheric pollutants (such as SO₂, CO₂, NO₂) and dust. This review provides assistance to the development of new corrosion-resistant magnesium alloys. Full article

(This article belongs to the Special Issue Microstructure, Corrosion and Mechanical Properties of Magnesium Alloys)

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16 pages, 7958 KiB

Open AccessArticle

Effect of Spherical θ Precipitation in 1.5 GPa Grade Tempered Martensitic Steel on the Occurrence of Delayed Fracture

by Jin Ikegawa, Shiyu Wang, Ken Saito, Shinichi Kato, Kazuhiko Yamazaki and Shinsuke Suzuki

Metals 2024, 14(9), 999; https://doi.org/10.3390/met14090999 - 1 Sep 2024

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Abstract

The objective of this study is to clarify the effect of spherical cementite (θ) precipitation on the occurrence of delayed fracture in 1.5 GPa grade tempered martensitic steels. Constant load tests were performed with a cathodically charged specimen. A 1GPa-load was applied to [...] Read more.

The objective of this study is to clarify the effect of spherical cementite (θ) precipitation on the occurrence of delayed fracture in 1.5 GPa grade tempered martensitic steels. Constant load tests were performed with a cathodically charged specimen. A 1GPa-load was applied to the specimen, and cathodic charging was performed in 3% NaCl + 3 g/L NH₄SCN solution. The specimen of steel without spherical θ did not fracture at the current density of 5 A·m⁻² or even by increasing to 50 A·m⁻². On the other hand, the specimen of steel with spherical θ fractured after 0.2 h at 5 A·m⁻². The strain around the spherical θ after 30%-rolling observed by transmission electron backscatter diffraction showed that the local deformation around the spherical θ was larger than that in the whole measurement field by 3.05 × 10¹⁴ m⁻² in terms of geometrically necessary dislocation density. In the hydrogen desorption curve by thermal desorption analysis, steel with spherical θ after 30%-rolling showed a larger hydrogen desorption peak around 250 °C than steel without spherical θ. The value of the activation energy of the 250 °C-peak was 109.2 kJ·mol⁻¹. From these results, the 250 °C-peak is inferred to be hydrogen at the disordered interface of θ/tempered martensite. Transmission electron microscopy observation showed cracks and voids on the spherical θ near the delayed fracture surface. These results indicate that the precipitation of spherical θ facilitates the occurrence of delayed fracture. Cracks appear to form around spherical θ. Full article

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16 pages, 10345 KiB

Open AccessArticle

Effect of Electromagnetic Field Assistance on the Wear and Corrosion Resistance of Nickel-Based Coating by Laser Cladding

by Dianxian Zhan, Dezhi Jiang, Yonggang Tong, Mingjun Zhang, Jian Zhang, Hongwei Hu, Zhenlin Zhang and Kaiming Wang

Metals 2024, 14(9), 998; https://doi.org/10.3390/met14090998 - 1 Sep 2024

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Abstract

Offshore wind turbine generators usually demand higher requirements for key component materials because of the adverse working environment. Therefore, in this study, electromagnetic-assisted laser cladding technology was introduced to prepare the nickel-based composite coating on the Q345R matrix of wind turbine generator key [...] Read more.

Offshore wind turbine generators usually demand higher requirements for key component materials because of the adverse working environment. Therefore, in this study, electromagnetic-assisted laser cladding technology was introduced to prepare the nickel-based composite coating on the Q345R matrix of wind turbine generator key component material. By means of Scanning Electron Microscope (SEM), X-ray diffraction (XRD), Energy Dispersive Spectrometer (EDS), the Vickers hardness tester, friction and wear tester, and electrochemical workstation, the effects of different magnetic field intensities on the macroscopic morphology, microstructure, phase composition, microhardness, wear resistance, and corrosion resistance of the coating were analyzed. The experimental results show that the addition of a magnetic field can effectively reduce the surface defects, improve the surface morphology, and not change the phase composition of the coating. With the increase in magnetic field intensity, the microstructure is gradually refined, and the average microhardness increases gradually, reaching a maximum of 944HV_0.5 at 8 T. The wear resistance gradually increases with the increase in magnetic field intensity, especially when the magnetic field intensity reaches 12 T, the wear rate of the coating is reduced by 81.13%, and the corrosion current density is reduced by 43.7% compared with the coating without a magnetic field. The addition of an electromagnetic field can enhance the wear resistance and corrosion resistance of the nickel-based laser cladding layer. Full article

(This article belongs to the Special Issue Advances in Preparation Methods and Numerical Simulation of Composites: Formation and Properties)

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11 pages, 2838 KiB

Open AccessArticle

Effect of Laser Energy Density on the Properties of CoCrFeMnNi High-Entropy Alloy Coatings on Steel by Laser Cladding

by Chenchen Ding, Qi Zhang, Siyu Sun, Hongjun Ni, Yu Liu, Xiao Wang, Xiaofeng Wan and Hui Wang

Metals 2024, 14(9), 997; https://doi.org/10.3390/met14090997 - 1 Sep 2024

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Abstract

High-entropy alloys (HEAs) have emerged as a novel class of materials with exceptional mechanical and corrosion properties, offering promising applications in various engineering fields. However, optimizing their performance through advanced manufacturing techniques, like laser cladding, remains an area of active research. This study [...] Read more.

High-entropy alloys (HEAs) have emerged as a novel class of materials with exceptional mechanical and corrosion properties, offering promising applications in various engineering fields. However, optimizing their performance through advanced manufacturing techniques, like laser cladding, remains an area of active research. This study investigated the effects of laser energy density on the mechanical and electrochemical properties of CoCrFeMnNi HEA coatings applied to Q235 substrates. Utilizing X-ray diffraction (XRD), this study confirmed the formation of a single-phase face-centered cubic (FCC) structure in all coatings. The hardness of the coatings peaked at 210 HV with a laser energy density of 50 J/mm². Friction and wear tests highlighted that a coating applied at 60 J/mm² exhibited the lowest wear rate, primarily due to adhesive and oxidative wear mechanisms, while the 55 J/mm² coating showed increased hardness but higher abrasive wear. Electrochemical testing revealed superior corrosion resistance for the 60 J/mm² coating, with a slow corrosion rate and minimal passivation tendency in contrast to the 55 J/mm² coating. The comprehensive evaluation indicates that the HEA coating with an energy density of 60 J/mm² exhibits exceptional wear and corrosion resistance. Full article

(This article belongs to the Special Issue Fabricating Advanced Metallic Materials)

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23 pages, 22899 KiB

Open AccessArticle

Influence of Ag Doping on Wide-Emperature Tribological Properties of γ-Fe₂O₃@SiO₂ Nanocomposite Coatings on Steel

by Qunfeng Zeng, Shichuan Sun and Qian Jia

Metals 2024, 14(9), 996; https://doi.org/10.3390/met14090996 - 1 Sep 2024

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Abstract

γ-Fe₂O₃@SiO₂-Ag nanocomposite coatings were prepared to investigate the lubrication performances of the nanocomposite coatings under a wide range of temperatures. The effect of Ag doping on the tribological properties of γ-Fe₂O₃@SiO₂-Ag [...] Read more.

γ-Fe₂O₃@SiO₂-Ag nanocomposite coatings were prepared to investigate the lubrication performances of the nanocomposite coatings under a wide range of temperatures. The effect of Ag doping on the tribological properties of γ-Fe₂O₃@SiO₂-Ag nanocomposite coatings was studied from room temperature to 600 °C, and the synergistic effect of Ag and oxides in the nanocomposite coatings was investigated. The coefficient of friction and the wear rate of γ-Fe₂O₃@SiO₂-Ag nanocomposite coatings decrease with an increase in Ag content. The tribological properties of 24 wt.%Ag of the nanocomposite coatings are excellent. The stable coefficient of friction is 0.25 at 100 °C and the coefficient of friction is reduced to 0.05 at 500 °C. It was found that the synergistic effect of γ-Fe₂O₃ and Ag is helpful in improving the tribological properties of γ-Fe₂O₃@SiO₂-Ag nanocomposite coatings over a wide temperature range. Ag plays a lubricating role at low and medium temperatures and oxides play a role in lubrication at high temperatures. Full article

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19 pages, 13377 KiB

Open AccessArticle

Prediction of Failure Due to Fatigue of Wire Arc Additive Manufacturing-Manufactured Product

by Sergei Mancerov, Andrey Kurkin, Maksim Anosov, Dmitrii Shatagin, Mikhail Chernigin and Julia Mordovina

Metals 2024, 14(9), 995; https://doi.org/10.3390/met14090995 - 1 Sep 2024

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Abstract

Currently, the focus of production is shifting towards the use of innovative manufacturing techniques and away from traditional methods. Additive manufacturing technologies hold great promise for creating industrial products. The industry aims to enhance the reliability of individual components and structural elements, as [...] Read more.

Currently, the focus of production is shifting towards the use of innovative manufacturing techniques and away from traditional methods. Additive manufacturing technologies hold great promise for creating industrial products. The industry aims to enhance the reliability of individual components and structural elements, as well as the ability to accurately anticipate component failure, particularly due to fatigue. This paper explores the possibility of predicting component failure in parts produced using the WAAM (wire arc additive manufacturing) method by employing fractal dimension analysis. Additionally, the impact of manufacturing imperfections and various heat treatment processes on the fatigue resistance of 30CrMnSi steel has been investigated. Fatigue testing of samples and actual components fabricated via the WAAM process was conducted in this study. The destruction of the examined specimens and products was predicted by evaluating the fractal dimensions of micrographs acquired at different stages of fatigue testing. It has been established that technological defects are more dangerous in terms of fatigue failure than microstructural ones. The correctly selected mode of heat treatment for metal after electric arc welding allows for a more homogeneous microstructure with a near-complete absence of microstructural defects. A comparison of the fractal dimension method with other damage assessment methods shows that it has high accuracy in predicting part failure and is less labor-intensive than other methods. Full article

(This article belongs to the Section Additive Manufacturing)

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24 pages, 13050 KiB

Open AccessArticle

Features of Increasing the Wear Resistance of 90CrSi Tool Steel Surface under Various Electrophysical Parameters of Plasma Electrolytic Treatment

by Sergey N. Grigoriev, Ivan V. Tambovskiy, Tatiana L. Mukhacheva, Irina A. Kusmanova, Pavel A. Podrabinnik, Nikolay O. Khmelevsky, Igor V. Suminov and Sergei A. Kusmanov

Metals 2024, 14(9), 994; https://doi.org/10.3390/met14090994 - 31 Aug 2024

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Abstract

The paper investigates the feasibility of plasma electrolytic treatment (PET) of 90CrSi tool steel to enhance hardness and wear resistance. The influence of electrophysical parameters of PET (polarity of the active electrode, chemical-thermal treatment, and polishing modes) on the composition, structure, morphology, and [...] Read more.

The paper investigates the feasibility of plasma electrolytic treatment (PET) of 90CrSi tool steel to enhance hardness and wear resistance. The influence of electrophysical parameters of PET (polarity of the active electrode, chemical-thermal treatment, and polishing modes) on the composition, structure, morphology, and tribological properties of the surface was studied. Tribological tests were carried out under dry friction conditions according to the shaft-bushing scheme with fixation of the friction coefficient and temperature in the friction contact zone, measurements of surface microgeometry parameters, morphological analysis of friction tracks, and weight wear. The formation of a surface hardened to 1110–1120 HV due to the formation of quenched martensite is shown. Features of nitrogen diffusion during anodic PET and cathodic PET were revealed, and diffusion coefficients were calculated. The wear resistance of the surface of 90CrSi steel increased by 5–9 times after anodic PET followed by polishing, by 16 times after cathodic PET, and up to 32 times after subsequent polishing. It is shown that in all cases, the violation of frictional bonds occurs through the plastic displacement of the material, and the wear mechanism is fatigue wear during dry friction and plastic contact. Full article

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16 pages, 8293 KiB

Open AccessArticle

Low-Carbon Steel Formed by DRECE Method with Hot-Dip Zinc Galvanizing and Potentiodynamic Polarization Tests to Study Its Corrosion Behavior

by Jiřina Vontorová, Vlastimil Novák and Petra Váňová

Metals 2024, 14(9), 993; https://doi.org/10.3390/met14090993 - 31 Aug 2024

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Abstract

The use of low-carbon unalloyed steel with minimal silicon content is widespread in structural steel and automotive applications due to its ease of manipulation. The mechanical properties of this steel can be significantly enhanced through severe plastic deformation (SPD) techniques. Our study focuses [...] Read more.

The use of low-carbon unalloyed steel with minimal silicon content is widespread in structural steel and automotive applications due to its ease of manipulation. The mechanical properties of this steel can be significantly enhanced through severe plastic deformation (SPD) techniques. Our study focuses on the practical benefits of the dual rolling equal channel extrusion (DRECE) method, which strengthens the steel and has implications for material hardness and the thickness of subsequently applied hot-dip zinc galvanizing. Furthermore, the steel’s corrosion potential and current are investigated as a function of material hardness and thickness. The findings show a 20% increase in hardness HV 30 after the first run through the forming machine, with an additional 10% increase after the second run. Subsequent galvanizing leads to a further 1–12% increase in HV 30 value. Notably, the DRECE hardening demonstrates no statistically significant effect on the corrosion potential and current; however, the impact of galvanizing is as anticipated. Full article

(This article belongs to the Special Issue Novel Insights and Advances in Steels and Cast Irons)

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20 pages, 11882 KiB

Open AccessArticle

Estimating the Cowper–Symonds Parameters for High-Strength Steel Using DIC Combined with Integral Measures of Deviation

by Andrej Škrlec, Branislav Panić, Marko Nagode and Jernej Klemenc

Metals 2024, 14(9), 992; https://doi.org/10.3390/met14090992 - 31 Aug 2024

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Abstract

Cowper–Symonds parameters were estimated for the complex-phase high-strength steel with a commercial name of SZBS800. The parameter estimation was based on a series of conventional tensile tests and unconventional high-strain rate experiments. The parameters were estimated using a reverse engineering approach. LS-Dyna was [...] Read more.

Cowper–Symonds parameters were estimated for the complex-phase high-strength steel with a commercial name of SZBS800. The parameter estimation was based on a series of conventional tensile tests and unconventional high-strain rate experiments. The parameters were estimated using a reverse engineering approach. LS-Dyna was used for numerical simulations, and the material’s response was modelled using a piece-wise linear plasticity model with a visco-plastic formulation of the Cowper–Symonds material model. A multi-criteria cost function was defined and applied to obtain a response function for the parameters p and C. The cost function was modelled with a response surface, and the optimal parameters were estimated using a real-valued genetic algorithm. The main novelty and innovation of this article is the definition of a cost function that measures a deviation between the deformed geometry of the flat plate-like specimens and the results of the numerical simulations. The results are compared to the relevant literature. A critical evaluation of our results and references is another novelty of this article. Full article

(This article belongs to the Special Issue Experimental and Numerical Investigation of Compression Behavior in Steel Structures)

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14 pages, 7107 KiB

Open AccessArticle

Effect of the Addition of Cu and Al on the Microstructure, Phase Composition and Properties of a Ti-6Al-4V Alloy Obtained by Selective Laser Melting

by Galina M. Zeer, Yuri I. Gordeev, Elena G. Zelenkova, Artur K. Abkaryan, Evgeny V. Gerasimov, Mikhail Yu. Kuchinskii and Sergey M. Zharkov

Metals 2024, 14(9), 991; https://doi.org/10.3390/met14090991 - 30 Aug 2024

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Abstract

The present study considers the samples of an Ti-6Al-4V alloy obtained by selective laser melting with the addition of a 10% Cu-Al powder mixture. The microstructure, elemental composition and phase composition, as well as the physico-chemical properties, have been investigated by the methods [...] Read more.

The present study considers the samples of an Ti-6Al-4V alloy obtained by selective laser melting with the addition of a 10% Cu-Al powder mixture. The microstructure, elemental composition and phase composition, as well as the physico-chemical properties, have been investigated by the methods of electron microscopy, X-ray phase analysis, and bending testing. The obtained samples have a relative density of 98.5 ± 0.1%. The addition of the Cu-Al powder mixture facilitates supercooling during crystallization and solidification, which allows decreasing the size and changing the shape of the initial β-Ti grains. The constant cooling rate of the alloy typical for the SLM technology has been shown to be able to prevent martensitic transformation. The formation of a structure that consists of β-Ti grains, a dispersed eutectoid mixture of α-Ti and Ti₂Cu grains, and a solid solution of Al in Cu has been revealed. In the case of doping by the 10% Cu-Al mixture, the physico-mechanical properties are improved. The hardness of the samples amounts to 390 HRC, with the bending strength being 1550 ± 20 MPa and deformation of 3.5 ± 0.2%. The developed alloy can be recommended for applications in the production of parts of jet and car engines, implants for medicine, and corrosion-resistant parts for the chemical industry. Full article

(This article belongs to the Section Additive Manufacturing)

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19 pages, 761 KiB

Open AccessArticle

Assessing Apparent Equilibrium Concentrations in Cementation of Trace Pd, Pt, Au, and Rh from Nitrate Solutions Using Mg, Al, Fe, and Zn

by Konrad Wojtaszek, Adrianna Pach, Tomasz Michalek, Kamil Dudek and Marek Wojnicki

Metals 2024, 14(9), 990; https://doi.org/10.3390/met14090990 - 30 Aug 2024

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Abstract

This study explores the impact of nitrate ions on the efficiency of cementing noble metals from diluted waste solutions at a temperature of 30 °C. The research involved measuring the effectiveness of different cementing metals (such as Zn, Al, Mg, and Fe) in [...] Read more.

This study explores the impact of nitrate ions on the efficiency of cementing noble metals from diluted waste solutions at a temperature of 30 °C. The research involved measuring the effectiveness of different cementing metals (such as Zn, Al, Mg, and Fe) in the presence of nitrate ions by assessing the change in metal ion concentrations before and after the cementation process using spectrometric analysis. Initial concentrations of noble metals ware Pt = 5 ppm, Au = 7.5 ppm, Pd = 5 ppm, and Rh = 1 ppm. Kinetic studies revealed that 24 h is adequate to achieve apparent equilibrium in solutions with pH 2 and 1 M nitrate ion content. The study identified significant recovery losses for gold and platinum in nitrate solutions, underlining the necessity of nitrate-free solutions in recycling. Zinc and magnesium were effective in cementing Pd and Rh, while aluminum was efficient for Pt reduction in each condition. Complete removal of Au was not achieved with any tested metal, indicating a need for alternative methods. Full article

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14 pages, 6765 KiB

Open AccessArticle

Behaviour of Dissimilar Welded Connections of Mild Carbon (S235), Stainless (1.4404), and High-Strength (S690) Steels under Monotonic and Cyclic Loading

by Anna Ene, Aurel Stratan and Ioan Both

Metals 2024, 14(9), 989; https://doi.org/10.3390/met14090989 - 29 Aug 2024

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Abstract

In the context of an increasing interest in the use of high-performance steels in the construction industry due to their superior mechanical properties, understanding the behaviour and assessing the performance of dissimilar welded connections becomes essential. When several steel grades are adopted for [...] Read more.

In the context of an increasing interest in the use of high-performance steels in the construction industry due to their superior mechanical properties, understanding the behaviour and assessing the performance of dissimilar welded connections becomes essential. When several steel grades are adopted for fabrication of the same dissipative element, dissimilar welded connections have a decisive importance regarding the seismic performance of the structural member. This paper presents the experimental results of monotonic and low-cycle fatigue (LCF) tests on dissimilar welded connections. The welded connections are designed to reproduce the loading state that occurs between the web and the flanges of dissipative links in an eccentrically braced frame, and represent combinations of S235 mild carbon steel, 1.4404 austenitic stainless steel, and S690 high-strength steel. The obtained experimental results provide a better understanding of the behaviour of dissimilar welded connections through the evaluation of their strength, ductility, and failure mechanisms, providing a basis for finite element (FE) models’ calibration for further numerical simulations. This study contributes to the evaluation of the feasibility of connections between dissimilar steels in seismic-resistant steel structures. Full article

(This article belongs to the Special Issue Experimental and Numerical Investigation of Compression Behavior in Steel Structures)

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20 pages, 12806 KiB

Open AccessArticle

Fatigue Response of Additive-Manufactured 316L Stainless Steel

by Melody Chepkoech, Peter Omoniyi and Gbadebo Owolabi

Metals 2024, 14(9), 988; https://doi.org/10.3390/met14090988 - 29 Aug 2024

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Abstract

This study investigated the fatigue performance of 316L stainless steel fabricated via laser powder bed fusion (LPBF). Stress-controlled fatigue tests were performed at different stress amplitudes on vertically built samples using a frequency of 15 Hz and a stress ratio of 0.1. The [...] Read more.

This study investigated the fatigue performance of 316L stainless steel fabricated via laser powder bed fusion (LPBF). Stress-controlled fatigue tests were performed at different stress amplitudes on vertically built samples using a frequency of 15 Hz and a stress ratio of 0.1. The stress amplitudes were varied to provide the cyclic response of the materials under a range of loading conditions. The average fatigue strength was determined to be 92.94 MPa, corresponding to a maximum stress of 185.87 MPa. The microstructures were observed through scanning electron microscopy (SEM) with the aid of electron backscattered diffraction (EBSD), and the average grain size of the as-built samples was determined to be 15.6 µm, with most grains having a <110> preferred crystallographic orientation. A higher kernel average misorientation value was measured on the deformed surfaces, revealing the increased misorientation of the grains. Defects were observed on the fractured surfaces acting as crack initiators while deflecting the crack propagation paths. The fatigue failure mode for the LPBF 316L samples was ductile, as illustrated by the numerous dimples on fracture surfaces and fatigue striations. Full article

(This article belongs to the Special Issue Mechanical Properties, Fatigue and Fracture of Metallic Materials)

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