Metals

11 pages, 3266 KiB

Open AccessArticle

Mechanical Properties of a Structural Component Processed in High-Pressure Die Casting (HPDC) with a Non-Heat-Treated Aluminum Alloy

by David Servando Cantú-Fernández, José Jaime Taha-Tijerina, Alejandro González, Pablo Guajardo Hernández and Brian Quinn

Metals 2024, 14(3), 369; https://doi.org/10.3390/met14030369 - 21 Mar 2024

Cited by 1 | Viewed by 1839

Abstract

This industrial research focuses on the implementation and development of a productive process for an automotive structural component (Shock tower) manufactured by a high-pressure die casting (HPDC) process made of aluminum alloy Aural^TM-5. This aluminum alloy has been considered in diverse [...] Read more.

This industrial research focuses on the implementation and development of a productive process for an automotive structural component (Shock tower) manufactured by a high-pressure die casting (HPDC) process made of aluminum alloy Aural^TM-5. This aluminum alloy has been considered in diverse automotive and aerospace components that do not require heat treatment due to its mechanical properties as cast material (F temper). On the other hand, Aural^TM-5 has been designed for processing as HPDC because it is an alloy with good fluidity, making it ideal for large castings with thin-wall thicknesses, like safety structural components such as rails, supports, rocker panels, suspension crossmembers, and shock towers. The mechanical properties that were evaluated for the evaluated components were yield strength, ultimate tensile strength, and elongation. Eight samples were taken from different areas of each produced shock tower for evaluating and verifying the homogeneity of each casting. The samples were evaluated from the first hours after they were manufactured by casting until eight weeks after being produced. This was performed to understand the behavior of the alloy during its natural aging process. Two groups of samples were obtained. One set of components was heat-treated by a water quench process after the castings’ extraction and the other set of components was not quenched. Results demonstrated that both sets of components, quenched and not quenched, achieved the expected values for the Aural^TM-5 of yield strength ≥ 110 MPa, ultimate tensile strength ≥ 240 MPa, and elongation ≥ 8%. Additionally, this is very important for industry since by not treating the structural components by quenching, there are savings in terms of infrastructure and energy consumption, together with benefits in the environmental aspect by avoiding CO₂ emissions and being sustainable. Full article

(This article belongs to the Section Metal Casting, Forming and Heat Treatment)

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20 pages, 11267 KiB

Open AccessArticle

The Angular Velocity as a Function of the Radius in Molten Ga75In25 Alloy Stirred Using a Rotation Magnetic Field

by András Roósz, Arnold Rónaföldi, Mária Svéda and Zsolt Veres

Metals 2024, 14(3), 368; https://doi.org/10.3390/met14030368 - 21 Mar 2024

Viewed by 959

Abstract

The simulation of the solidification of alloys (like steel or aluminium alloys), which is carried out by using the melt flow induced by a rotation magnetic field (RMF), needs the correct angular velocity vs. the radius function of the melt. Because it is [...] Read more.

The simulation of the solidification of alloys (like steel or aluminium alloys), which is carried out by using the melt flow induced by a rotation magnetic field (RMF), needs the correct angular velocity vs. the radius function of the melt. Because it is impossible to directly obtain information about the melt flow from industrial casting, this information can only be obtained from well-monitored experiments using low-melting-point metals or alloys (e.g., Hg, Ga, GaIn, and GaInSn). In this work, we first summarized the measuring methods that are suitable for determining this function and analysed their advantages and disadvantages. All of them disturb, to some degree, the melt flow, except for the Pressure Compensation Method (PCM); therefore, this method was used in the experiments. Closed TEFLON crucibles with a 60 mm length and 12.5 mm radius and Ga75wt%In25wt% alloy was used. The angular velocity (ω) was calculated from the compensation pressure measured at r = 5, 7.5, 10, and 12.5 mm in the 0–90 mT range of magnetic induction, B. Based on the ω(B, r) dataset, a suitable ω(B, r) function was determined for the simulation. Full article

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23 pages, 15689 KiB

Open AccessArticle

Steel Sheet Deformation in Clinch-Riveting Joining Process

by Waldemar Witkowski, Jacek Mucha and Łukasz Boda

Metals 2024, 14(3), 367; https://doi.org/10.3390/met14030367 - 21 Mar 2024

Cited by 1 | Viewed by 1088

Abstract

This paper presents the deformation of a joined sheet after the clinch riveting process. The DX51D steel sheet with zinc coating was used. The samples to be joined with clinch riveting technology had a thickness of 1 ± 0.05 mm and 1.5 ± [...] Read more.

This paper presents the deformation of a joined sheet after the clinch riveting process. The DX51D steel sheet with zinc coating was used. The samples to be joined with clinch riveting technology had a thickness of 1 ± 0.05 mm and 1.5 ± 0.1 mm. The sheet deformation was measured before and after the joining process. The rivet was pressed in the sheets with the same dimension between the rivet axis and three sheet edges: 20, 30, and 40 mm. For fixed segments of the die, from the rivet side close to the rivet, the sheet deformation was greater than that of the area with movable segments. The movement of the die’s sliding element caused more sheet material to flow in the space between the fixed part of the die and movable segments. Hence, the sheet deformation in these places was smaller than for the die’s fixed element—the sheet material was less compressed. For sheet thickness values of 1.5 mm and a width value of 20 mm, the bulk of the sheet was observed. For a sheet width of 20 mm, it was observed that the deformation of the upper and lower sheets in the area of the rivet was greater than for sheet width values of 30 or 40 mm. Full article

(This article belongs to the Special Issue New Technology of Welding/Joining of Metallic Materials)

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12 pages, 3777 KiB

Open AccessArticle

MgAl Oxide Coatings Modified with CeO₂ Particles Formed by Plasma Electrolytic Oxidation of AZ31 Magnesium Alloy: Photoluminescent and Photocatalytic Properties

by Stevan Stojadinović and Nenad Radić

Metals 2024, 14(3), 366; https://doi.org/10.3390/met14030366 - 21 Mar 2024

Cited by 1 | Viewed by 1074

Abstract

MgAl oxide coatings composed of MgO and MgAl₂O₄ phases were doped with CeO₂ particles via plasma electrolytic oxidation (PEO) of AZ31 magnesium alloy in a 5 g/L NaAlO₂ water solution. Subsequently, particles of CeO₂ up to 8 [...] Read more.

MgAl oxide coatings composed of MgO and MgAl₂O₄ phases were doped with CeO₂ particles via plasma electrolytic oxidation (PEO) of AZ31 magnesium alloy in a 5 g/L NaAlO₂ water solution. Subsequently, particles of CeO₂ up to 8 g/L were added. Extensive investigations were conducted to examine the morphology, the chemical and phase compositions, and, most importantly, the photoluminescent (PL) properties and photocatalytic activity (PA) during the photodegradation of methyl orange. The number of CeO₂ particles incorporated into MgAl oxide coatings depends on the concentration of CeO₂ particles in the aluminate electrolyte. However, the CeO₂ particles do not significantly affect the thickness, phase structure, or surface morphology of the coatings. The PL emission spectrum of MgAl oxide coatings is divided into two bands: one in the 350–600 nm range related to structural defects in MgO, and another much more intense band in the 600–775 nm range attributed to the F⁺ centres in MgAl₂O₄. The incorporated CeO₂ particles do not have a significant effect on the PL intensity of the band in the red spectral region, but the PL intensity of the first band increases with the concentration of CeO₂ particles. The PA of MgAl/CeO₂ oxide coatings is higher than that of pure MgAl oxide coatings. The MgAl/CeO₂ oxide coating developed in aluminate electrolyte with a concentration of 2 g/L CeO₂ particles exhibited the highest PA. The MgAl/CeO₂ oxide coatings remained chemically and physically stable across multiple cycles, indicating their potential for applications. Full article

(This article belongs to the Topic Materials and Surface Treatment Processes Used for Engineering Applications)

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Voltage–time curves during anodization in 5 g/L NaAlO2 without and with 8 g/L of CeO2 particles. Full article ">Figure 2
(a) Top view and (b) cross-section micrographs of coatings formed in 5 g/L NaAlO2 by adding CeO2 particles in concentrations of (i) 0 g/L; (ii) 1 g/L; (iii) 2 g/L; (iv) 4 g/L; (v) 8 g/L. Full article ">Figure 3
(a) XRD patterns and (b) Raman spectra of coatings formed in 5 g/L NaAlO2 with varying concentrations of CeO2 particles. Full article ">Figure 4
PL excitation and emission spectra of MgO/MgAl2O4 coatings: (a) λex = 265 nm, λem = 720 nm; (b) λex = 340 nm, λem = 410 nm. Full article ">Figure 5
PL spectra of MgO/MgAl2O4/CeO2 coatings formed in 5 g/L NaAlO2 with varying concentrations of CeO2 particles: (a) emission spectra excited at 265 nm; (b) emission spectra excited at 340 nm; (c) excitation spectra monitored at 720 nm; (d) excitation spectra monitored at 410 nm; (e) excitation spectra monitored at 520 nm. Full article ">Figure 6
(a) PA and (b) first-order kinetic plots of coatings formed in 5 g/L NaAlO2 with varying concentrations of CeO2 particles. Full article ">Figure 7
DRS spectra of CeO2 particles and coatings formed in 5 g/L NaAlO2 with varying concentrations of CeO2 particles added. Full article ">Figure 8
(a) MO photodegradation recycling experiment; (b) SEM micrographs before and after 10 cycles; and (c) XRD patterns before and after 10 cycles of a coating formed in 5 g/L NaAlO2 + 2 g/L CeO2. Full article ">

11 pages, 4481 KiB

Open AccessArticle

Effect of Coiling Temperature on Microstructure and Properties of Ferritic-Bainitic Dual-Phase Steels

by Zhengrong Li, Feng Zhou, Jinhai Liu, Lei Liu, Chuangwei Wang and Zhengzhi Zhao

Metals 2024, 14(3), 365; https://doi.org/10.3390/met14030365 - 21 Mar 2024

Viewed by 1074

Abstract

In this study, a 780 MPa grade ferritic-bainitic dual-phase steel with excellent matching of strength-plasticity and formability was developed using thermomechanical control processing. Optical microscopy, Scanning electron microscopy, and Electron Backscatter Diffraction techniques were used to characterize the microstructure comprehensively, and the effects [...] Read more.

In this study, a 780 MPa grade ferritic-bainitic dual-phase steel with excellent matching of strength-plasticity and formability was developed using thermomechanical control processing. Optical microscopy, Scanning electron microscopy, and Electron Backscatter Diffraction techniques were used to characterize the microstructure comprehensively, and the effects of coiling temperature on the microstructure, the strength-plasticity, and hole-expansion ratio of the test steels were thoroughly investigated. The results showed that the test steel had an excellent combination of ferrite and bainite at the coiling temperature of 520 °C, 23.7 and 76.3%, respectively, with a hole expansion ratio of 58.5 ± 2.8%. The uniformity of the microstructure was the key to obtaining a high expansion ratio in ferrite-bainite dual-phase steels. The test steels formed granular bainite at low-temperature coiling, while polygonal ferrite was promoted at high-temperature coiling. The effect of coiling temperature on grain size is small. Dislocations were redistributed during high-temperature coiling, resulting in a decrease in dislocation density. The higher elongation and hole expansion rate at higher coiling temperatures were attributed to increased polygonal ferrite content, reduced grain size, and enhanced TRIP effect. When coiling at low temperatures, the agglomeration of polygonal ferrite or granular bainite tends to result in a non-uniform distribution of the soft and hard phases of the matrix. At the same time, the strong texture parallel to the rolling direction has a significant difference in plasticity in different directions, leading to non-uniform deformation, which is liable to stress concentration, causing crack nucleation and extension in the hole expanding process, thus reducing the hole expansion performance. Full article

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Schematic diagram of the TMCP for test steel. Full article ">Figure 2
Tensile specimen machining schematic. Full article ">Figure 3
Schematic diagrams of the punching and hole-expanding test. Full article ">Figure 4
Optical microstructure of test steel at coiling temperatures 480 °C and 520 °C. (a) CT of 480 °C; (b) CT of 520 °C. Full article ">Figure 5
SEM micrographs of test steel at coiling temperatures of 480 °C and 520 °C: (a,c) are SEM micrographs at coiling temperatures of 480 °C and 520 °C, respectively; (b,d) are the local magnification of the rectangle region marked by the white line in (a,c), respectively. Full article ">Figure 6
GOS, GNDdensity, and IPF maps of test steels at coiling temperatures of 480 °C and 520 °C. (a1–a3) 480 °C; (b1–b3) 520 °C; (a1,b1) are GOS maps, (a2,b2) are GND density maps, (a3,b3) are IPF maps. Full article ">Figure 7
The fine structure of PF and granular bainite in region I. (a) IPF map; (b) GOS map; (c) GND density map. Full article ">Figure 8
BCC and FCC crystal structures of test steels at coiling temperatures of 480 °C and 520 °C. (a) 480 °C; (b) 520 °C; red represents BCC crystal structure and green represents FCC crystal structure. Full article ">

13 pages, 7906 KiB

Open AccessArticle

The Study on Corrosion Resistance of Ti-6Al-4V ELI Alloy with Varying Surface Roughness in Hydrofluoric Acid Solution

by Han Wang, Quanshi Cheng, Zhuo Chang, Kedi Wang, Xuemin Gao and Xueling Fan

Metals 2024, 14(3), 364; https://doi.org/10.3390/met14030364 - 20 Mar 2024

Viewed by 1134

Abstract

The corrosion resistance of titanium alloy poses a crucial challenge, significantly affecting its prospect for service and application. The present study aimed to investigate the corrosion resistance of Ti-6Al-4V ELI alloys with varying surface roughness in hydrofluoric acid solution, in order to assess [...] Read more.

The corrosion resistance of titanium alloy poses a crucial challenge, significantly affecting its prospect for service and application. The present study aimed to investigate the corrosion resistance of Ti-6Al-4V ELI alloys with varying surface roughness in hydrofluoric acid solution, in order to assess the influence of roughness on their corrosion resistance performance. The weight loss percentage, surface morphology evolution, and roughness variation of Ti-6Al-4V ELI alloys before and after exposure to hydrofluoric acid corrosion were characterized. While the weight loss and weight loss percentage of the Ti-6Al-4V ELI alloy increased with prolonged corrosion, the overall weight loss rate decreased. The accumulation of TiF₃ phases and depletion of the Ti-6Al-4V ELI matrix mutually led to the alterations of the surface roughness. Due to the inability to prevent fluoride ions from contacting with the Ti-6Al-4V ELI alloy, continuous corrosion occurred in hydrofluoric acid. Based on these experimental results and analysis, the corrosion mechanism of the Ti-6Al-4V ELI alloy corroded by hydrofluoric acid solution was elucidated. Furthermore, an analysis was conducted to explore the influence of corrosion time on mechanical properties by analyzing the decay in compressive properties of the Ti-6Al-4V ELI titanium alloy after hydrofluoric acid corrosion treatment. The bearing capacity of the Ti-6Al-4V ELI alloy deteriorated over the corrosion time. Full article

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17 pages, 7347 KiB

Open AccessArticle

Effects of Different CaO/Al₂O₃ Ratios on the Phase Composition and Desulfurization Ability of CaO-Based Desulfurizers in Hot Metal

by Jyun-Ming Shen, Chi-Ming Lin, Yu-En Chang, Hui-Jan Lin and Weite Wu

Metals 2024, 14(3), 363; https://doi.org/10.3390/met14030363 - 20 Mar 2024

Viewed by 1038

Abstract

In response to the development of low-carbon smelting technology, reducing the use of fluor-containing materials in desulfurizers is an important research topic. The development of new-generation KR (Kambara Reactor) desulfurizers is shifting towards a higher Al₂O₃ content rather than CaF [...] Read more.

In response to the development of low-carbon smelting technology, reducing the use of fluor-containing materials in desulfurizers is an important research topic. The development of new-generation KR (Kambara Reactor) desulfurizers is shifting towards a higher Al₂O₃ content rather than CaF₂, yet there is currently an absence of thorough and comprehensive mechanisms for desulfurization. Consequently, this research provides an extensive comparison using a specially constructed small-scale KR desulfurization hot model test, alongside FactSage simulation and SEM analysis (of desulfurization process). The findings indicate that at 1400 °C, for the desulfurization of molten iron, the capacity for desulfurization initially increases and then diminishes as the Al₂O₃ content in the KR desulfurizer rises. With Al₂O₃ content in the desulfurizer below 22 wt.%, the phase composition predominantly consists of C₃A, employing a solid_(slag)–liquid_(metal) diffusion method for desulfurization. The optimal desulfurization capacity (Ls: 64.1) is observed when the Al₂O₃ content is 15 wt.%, attributed to the simultaneous presence of CaO particle precipitation and C₃A. However, as the Al₂O₃ content reaches 20 wt.%, all the oversaturated CaO integrates into C₃A, leading to a reduction in Ls from 64.1 to 10.7, thereby diminishing the desulfurization capacity by approximately sixfold. When Al₂O₃ exceeds 22 wt.%, the phase composition transitions from the C₃A to C₁₂A₇ phase, and the desulfurization approach shifts from solid_(slag)–liquid_(metal) to liquid_(slag)–liquid_(metal) diffusion, with Ls decreasing to 23.4. This reduction is due to C₁₂A₇’s lower sulfur capacity compared to C₃A and the absence of saturated CaO particle precipitation. Therefore, for Al₂O₃ to effectively replace fluorite in KR desulfurizers, a higher presence of C₃A phases and CaO particle precipitation are essential. The desulfurizer must contain over 65 wt.% CaO and maintain A_l2O₃ levels at 10~16.2 wt.%. Full article

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11 pages, 10641 KiB

Open AccessArticle

Morphological Evolution of Single-Core Multi-Strand Wires during Ultrasonic Metal Welding

by Andreas Gester, Dmitrii Ozherelkov and Guntram Wagner

Metals 2024, 14(3), 362; https://doi.org/10.3390/met14030362 - 20 Mar 2024

Viewed by 1015

Abstract

Ultrasonic metal welding (USMW) finds widespread utilization in automotive industries, where it is used for connecting the wire harness of the vehicle, consisting of stranded wires, to the terminals. However, the behavior of the strands during the compaction process is still understudied and [...] Read more.

Ultrasonic metal welding (USMW) finds widespread utilization in automotive industries, where it is used for connecting the wire harness of the vehicle, consisting of stranded wires, to the terminals. However, the behavior of the strands during the compaction process is still understudied and often overlooked. Therefore, this work focuses on the investigation of the wire compaction behavior from a morphological point of view. A newly developed method for investigating cross-sections of such joints is introduced, facilitating area quantification of the strands for a microscale examination of compaction variations for every single strand as a function of welding time. It is shown that the deformation in the wire is not homogenous throughout the wire cross-section; instead, the formation of distinct zones is observed. Three distinct regimes dominating the welding process were observed: (i) linear reduction in nugget height with primary compaction of the nugget and sealing of the interstitial spaces between the strands for weld times from 0 s up to 1.3 s; (ii) accelerated loss of nugget height due to strong plastic deformation of the strands for weld times between 1.3 s and 1.7 s; and (iii) comprehensive welding of the individual strands and strong loss of nugget height. Furthermore, it was demonstrated that the deformation of the wire during the USMW process originates in the coupling area of the horn and the wire and not in the interface of the wire and the terminal. Therefore, it can be assumed that the temperature of the interface between the horn and the wire must be significantly higher than that of the interface between the wire and the terminal. The presented approach and new insights into the behavior of ultrasonically welded joints of stranded wires and terminals provide guidance for improving the welding process. Full article

(This article belongs to the Special Issue Ultrasonic Welding: Joining of Metals and Multi-Material Structures by Power Ultrasonics)

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2 pages, 148 KiB

Open AccessCorrection

Correction: Gargalis et al. A Comparative Investigation of Duplex and Super Duplex Stainless Steels Processed through Laser Powder Bed Fusion. Metals 2023, 13, 1897

by Leonidas Gargalis, Leonidas Karavias, Joachim S. Graff, Spyros Diplas, Elias P. Koumoulos and Evangelia K. Karaxi

Metals 2024, 14(3), 361; https://doi.org/10.3390/met14030361 - 20 Mar 2024

Viewed by 758

Abstract

In the original publication [...] Full article

(This article belongs to the Special Issue Selected Papers from 7th International Conference of Engineering Against Failure (ICEAF VII))

17 pages, 5100 KiB

Open AccessArticle

Cu_2−xS and Cu_2−xSe Alloys: Investigating the Influence of Ag, Zn, and Ni Doping on Structure and Transport Behavior

by Andrzej Mikuła, Tomasz Kurek, Miłosz Kożusznik and Paweł Nieroda

Metals 2024, 14(3), 360; https://doi.org/10.3390/met14030360 - 20 Mar 2024

Cited by 1 | Viewed by 1003

Abstract

Cu_2−xS and Cu_2−xSe (0 ≤ x ≤ 0.2) alloys stand out as highly promising materials for thermoelectric applications, owing to the phonon–liquid electron–crystal (PLEC) convention. In this study, we undertake a comprehensive investigation to reassess the synthesis [...] Read more.

Cu_2−xS and Cu_2−xSe (0 ≤ x ≤ 0.2) alloys stand out as highly promising materials for thermoelectric applications, owing to the phonon–liquid electron–crystal (PLEC) convention. In this study, we undertake a comprehensive investigation to reassess the synthesis conditions, with a focus on achieving pure-phased systems through a direct reaction between elements at elevated temperatures. Simultaneously, we present experimental evidence showcasing the feasibility of doping these systems with Ag, Ni, and Zn. The study demonstrates that obtaining single-phased systems requires multi-step processes, and the dissolution of chosen impurities appears doubtful, as evidenced by numerous foreign phase segregations. Additionally, it is revealed that the partial dissolution of individual impurities deteriorates the operational parameters of these chalcogenides. For the optimal Cu_1.97S composition, it reduces the thermoelectric figure-of-merit ZT from 1.5 to approximately 1.0, 0.65, and 0.85 for Ag-, Ni-, and Zn-doped systems, respectively, while marginally improving their stability. For metal-like Cu_1.8Se, the ZT parameter remains at a low level, ranging between 0.09 and 0.15, showing slight destabilization during subsequent operating cycles. The article concludes with an in-depth analysis of the basic thermoelectric performance exhibited by these doped systems, contributing valuable insights into the potential enhancements and applications of Cu_2−xS and Cu_2−xSe alloys in the field of thermoelectric materials. Full article

(This article belongs to the Special Issue Nano-Metallic Materials for New Energy)

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19 pages, 8387 KiB

Open AccessArticle

Mechanism of Crystallographic Orientation and Texture Evolution of Ti60 Alloy during Plane Strain Compression

by Yi Dai, Yunteng Xiao, Weidong Zeng, Runchen Jia and Weiju Jia

Metals 2024, 14(3), 359; https://doi.org/10.3390/met14030359 - 20 Mar 2024

Viewed by 966

Abstract

The crystallographic orientation and texture evolution mechanism of equiaxed Ti60 alloy plates were investigated in this study through plane strain compression tests. The EBSD analysis revealed that the received plate contained two characteristic textures that were perpendicular to each other, i.e., c-axis//TD (Component [...] Read more.

The crystallographic orientation and texture evolution mechanism of equiaxed Ti60 alloy plates were investigated in this study through plane strain compression tests. The EBSD analysis revealed that the received plate contained two characteristic textures that were perpendicular to each other, i.e., c-axis//TD (Component 1) and c-axis//RD (Component 2), with the latter being caused by the change in direction of the TD texture that was generated during the previous unidirectional rolling process into an RD direction in the cross-rolling process. The results demonstrated that, with increasing the deformation temperature from 930 °C to 960 °C and 990 °C, the intensity of the c-axis//TD texture (Component 1) initially rose to a peak value of 5.07, which then—subsequently—decreased significantly to 2.96 at 960 °C and 3.11 at 990 °C. Conversely, the intensity of the c-axis//RD texture (Component 2) remained relatively unchanged. These texture changes were correlated with slip system activity and the spheroidization of the primary alpha phase. For the c-axis//TD texture, the initial intensity of the texture components during compression at lower temperatures could be attributed to the incomplete dynamic spheroidization process of the α phase, which leads to the reinforcement of the c-axis//TD due to prismatic slip. As the deformation temperature increased, the dynamic spheroidization process became more prominent, thereby leading to a significant reduction in the intensity of the c-axis//TD texture. In contrast, the c-axis//RD texture exhibited difficulty in activating the prismatic slip and basal slip; in addition, it also encountered resistance to dynamic spheroidization, thus resulting in negligible changes in the texture intensity. Full article

(This article belongs to the Special Issue Design, Phase Transformation and Mechanical Properties of Titanium Alloy)

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8 pages, 5342 KiB

Open AccessCommunication

Metallurgical Method of Determining Heat Transfer Coefficient in Simulations of Twin-Roll Casting

by Min-Seok Kim and Jiwon Kim

Metals 2024, 14(3), 358; https://doi.org/10.3390/met14030358 - 20 Mar 2024

Cited by 3 | Viewed by 1031

Abstract

We herein suggest a metallurgical method using pure aluminum with no freezing temperature range to derive appropriate roll/melt interfacial heat transfer coefficients in simulation of twin-roll casting process. This method is inspired by the concept that the position of the kiss points where [...] Read more.

We herein suggest a metallurgical method using pure aluminum with no freezing temperature range to derive appropriate roll/melt interfacial heat transfer coefficients in simulation of twin-roll casting process. This method is inspired by the concept that the position of the kiss points where two solidifying shells encounter and the roll nip coincides under the condition where the roll load becomes zero as the roll rotation speed decreases. The conditions where the roll load becomes zero under various melt supply temperature conditions in the actual TRC process are found experimentally. These conditions are then applied to simulation models to derive heat transfer coefficient values. When comparing these values with those derived previously from the empirical relation for roll rotation speed and heat transfer coefficient, the conclusion is drawn that the deviation was reasonably low, around 10%. Full article

(This article belongs to the Special Issue Analysis, Design, Simulation and Practice of Aluminum Alloy Structures)

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11 pages, 3104 KiB

Open AccessArticle

A Study on the Aging Behavior of Nitrided W18Cr4V Steel in High-Temperature Sodium

by Xiaogang Fu, Na Liang, Wei Zhang, Liu Tao, Bo Qin, Zhangshun Ruan, Bin Long and Shasha Lv

Metals 2024, 14(3), 357; https://doi.org/10.3390/met14030357 - 19 Mar 2024

Viewed by 862

Abstract

The loading and unloading elevators are the primary equipment in the refueling system, used for transferring fuel assemblies in the sodium-cooled fast reactors. The guideway friction pairs are the critical components of these elevators in the refueling system. With the excellent hardness and [...] Read more.

The loading and unloading elevators are the primary equipment in the refueling system, used for transferring fuel assemblies in the sodium-cooled fast reactors. The guideway friction pairs are the critical components of these elevators in the refueling system. With the excellent hardness and wear resistance in air, nitrided W18Cr4V steel is a promising material for the guideway friction pairs. In order to assess the feasibility of using nitrided W18Cr4V steel, it is essential to understand the aging behavior of nitrided W18Cr4V steel in high-temperature sodium. Aging tests were conducted on nitrided W18Cr4V steel in sodium and in argon environments at various temperatures for different exposure times. The results showed that the nitrogen atoms in the nitrided layer exhibited bidirectional diffusion behavior in the sodium or argon environment at 540 °C. Compared to the argon environment, cracks formed within the nitrided layer and the diffusion of nitrogen into the sodium was accelerated in the nitrided layer. As a significant number of nitrogen atoms had diffused into the sodium, there was little difference in the hardness between nitrided W18Cr4V steel and non-nitrided W18Cr4V steel after long-term exposure to 540 °C sodium. Full article

(This article belongs to the Special Issue Corrosion-Related Failure Analysis in Industrial Components and Equipment)

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The characterization results of W18Cr4V steel before and after the ion nitriding process: (a) The microstructure of W18Cr4V steel before ion nitriding process, (b) The XRD result of W18Cr4V steel before and after ion nitriding process. Full article ">Figure 2
The microhardness test results of nitrided W18Cr4V steel after 200 h aging in sodium and argon at 540 °C. Full article ">Figure 3
The results of the microhardness examinations of nitrided W18Cr4V steel before and after aging tests: (a) aging in sodium at 540 °C for 200 h and 500 h, (b) aging in argon at 540 °C for 200 h and 500 h. Full article ">Figure 4
The SEM results of nitrided W18Cr4V steel after 200 h aging in sodium and argon at 540 °C: (a) aging in sodium, (b) aging in argon. Full article ">Figure 5
The XRD patterns of nitrided W18Cr4V steel before and after aging in sodium and argon environments at 540 °C for 200 h and 500 h. Full article ">Figure 6
The results of accelerated tests conducted on nitrided W18Cr4V steel and non-nitrided W18Cr4V steel in a sodium environment at a temperature of 700 °C. Full article ">

12 pages, 2801 KiB

Open AccessArticle

Movement Strategy Influences on the Characteristics of Low-Carbon Steel Generated by the Lamination Object Manufacturing Method

by Tran Le Hong Ngoc, Ha Thi Xuan Chi, Pham Son Minh, Van-Thuc Nguyen and Tran Minh The Uyen

Metals 2024, 14(3), 356; https://doi.org/10.3390/met14030356 - 19 Mar 2024

Viewed by 992

Abstract

This paper investigates the effects of heating movement techniques on the properties of low-carbon steel samples that are 3D printed using S20C lamination object manufacturing (LOM). A Tungsten iner gas (TIG) machine and a computer numerical control (CNC) machine were used together to [...] Read more.

This paper investigates the effects of heating movement techniques on the properties of low-carbon steel samples that are 3D printed using S20C lamination object manufacturing (LOM). A Tungsten iner gas (TIG) machine and a computer numerical control (CNC) machine were used together to join the steel sheet. The LOM samples were created with a straight-profile, short-profile, cross-profile, and curved-profile. The results indicate that the majority of the samples had a grain size number of 7–9. The samples exhibited an isotropy grain shape. The LOM samples exhibited dimples, which suggests ductility fractures. Pore flaws showed up in the microstructure of the cross-profile and short-profile samples during the LOM process. The samples with curved- and straight-profiles had a better microstructure. In comparison to samples with a short profile and a cross-profile, the samples with a straight-profile and a curved-profile had a superior combination of ultimate tensile strengths (UTSs) and elongation value. The straight- and curved-profiles’ greater elongation and tensile strength can be attributed to their improved microstructure and finer grain size. A straight-profile sample with an elongation value of 25.6% and a UTS value of 430 MPa was the ideal LOM sample. Conversely, the weakest sample was the LOM sample with a cross-profile, which had an elongation value of 10.8% and a UTS value of 332.5 MPa. This research could provide further information about the LOM method and the best straight-profile movement strategy. A suitable TIG gun movement strategy could produce a good LOM sample with a good microstructure, tensile strength, and ductility. Further research should incorporate more movement strategies and techniques that completely prevent the formation of pore defects. Full article

(This article belongs to the Special Issue Additive Manufacturing for Tooling Applications: Materials, Design, Processes & Impacts)

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20 pages, 4215 KiB

Open AccessArticle

Surface Residual Stress Release Behavior of Shot-Peened Springs

by Chenxi Shao, Decheng Wang, Yong Zang and Peng Cheng

Metals 2024, 14(3), 355; https://doi.org/10.3390/met14030355 - 19 Mar 2024

Viewed by 1043

Abstract

Shot peening is the primary method used to improve the fatigue life of springs. In this study, we aimed to quantify the reduction in residual stresses in the shot-peened layer by considering factors such as surface roughness, cyclic loading, and the helix angle, [...] Read more.

Shot peening is the primary method used to improve the fatigue life of springs. In this study, we aimed to quantify the reduction in residual stresses in the shot-peened layer by considering factors such as surface roughness, cyclic loading, and the helix angle, based on the spring’s periodic variation and curvature characteristics. We developed an equivalent replacement algorithm to address the challenge of characterizing the dynamic accumulation and attenuation of residual stresses under cyclic multiaxial stresses. This algorithm accurately modeled the dynamic attenuation of residual stresses and was incorporated into the spring life prediction model. Experimental validation demonstrated the high accuracy of the model for predicting fatigue life. Full article

(This article belongs to the Section Metal Failure Analysis)

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14 pages, 37796 KiB

Open AccessArticle

Microgrid-Patterned Ni Foams as Current Collectors for Ultrafast Energy Storage Devices

by Un-Tae Kim, Myeong-Hun Jo and Hyo-Jin Ahn

Metals 2024, 14(3), 354; https://doi.org/10.3390/met14030354 - 19 Mar 2024

Cited by 1 | Viewed by 979

Abstract

Current research is focused on developing active materials through surface functionalization, porosity, composites, and doping for ultrafast electric double layer capacitors (EDLCs). In this study, deviating from existing strategies focused on active materials, we designed tunable 3D microgrid-patterned (MP) surface morphologies on Ni [...] Read more.

Current research is focused on developing active materials through surface functionalization, porosity, composites, and doping for ultrafast electric double layer capacitors (EDLCs). In this study, deviating from existing strategies focused on active materials, we designed tunable 3D microgrid-patterned (MP) surface morphologies on Ni foams used as current collectors using SUS meshes as rigid stamps during roll pressing. The surface geometries of the MP-Ni foams were controlled to standard mesh scales of 24, 40, and 60 (denoted as 24MP-Ni, 40MP-Ni, and 60MP-Ni, respectively). The three MP-Ni samples with different microgrid sizes presented different surface geometries, such as root-mean-square roughness (R_rms), skewness roughness (R_sk), and width/depth scales of the microgrid patterns. Consequently, 40MP-Ni demonstrated an optimized surface geometry with high R_rms (35.4 μm) and R_sk (−0.19) values, which facilitated deep slurry infiltration and increased its contact area with the active material. Surface optimization of the MP-Ni enabled ultrafast and reversible charge transport kinetics owing to its relaxed electron transfer resistance and robust adhesion to the active material compared with bare Ni foam. EDLC electrodes with 40MP-Ni achieved an ultrafast-rate capability (96.0 F/g at 20 A/g) and ultrafast longevity (101.9% capacity retention after 5000 cycles at 5 A/g) without specific modification of active material. Full article

(This article belongs to the Special Issue Metallic Nanostructured Materials and Thin Films)

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(a) Schematic illustration of the microgrid-patterning of Ni foams using SUS meshes of different mesh sizes: (b) 24 mesh, (c) 40 mesh, and (d) 60 mesh. Photographs of the resultant Ni foams: (e) bare Ni, (f) 24MP-Ni, (g) 40MP-Ni, and (h) 60MP-Ni. Full article ">Figure 2
3D micro-topography images of the Ni foams fabricated by the microgrid patterning method: (a) bare Ni, (b) 24MP-Ni, (c) 40MP-Ni, and (d) 60MP-Ni. (e–h) Top-view surface roughness images of Ni foams and (i–l) the corresponding line roughness profiles: (e,i) bare Ni, (f,j) 24MP-Ni, (g,k) 40MP-Ni, and (h,l) 60MP-Ni. Full article ">Figure 3
(a) Surface geometry parameters (i.e., the width, depth, root-mean-square roughness (Rrms), and skewness roughness (Rsk) of the Ni foams. (b) Illustration of the infiltration of the surfaces of Ni foams with a highly negative Rsk and slightly negative Rsk. Full article ">Figure 4
(a) Raman spectrum and (b) nitrogen adsorption/desorption curves of YP50F. XRD patterns of the (c) Ni foam samples and (d) YP50F/Ni electrodes. OM images of the Ni foams: (e) bare Ni, (f) 24MP-Ni, (g) 40MP-Ni, and (h) 60MP-Ni. Full article ">Figure 5
Galvanostatic charge–discharge curves of the Ni foam-based electrodes at different current densities: (a) YP50F/bare Ni, (b) YP50F/24MP-Ni, (c) YP50F/40MP-Ni, and (d) YP50F/60MP-Ni. Full article ">Figure 6
(a) Specific capacitance and CE plots according to the current density in the range of 0.2–20 A/g for all EDLC electrodes. (b) CV profiles of the Ni foam-based electrodes in the potential range of 0–1.0 V. (c) Capacitance retention and high-rate capability plots according to cycle number and current density, respectively. (d) Specific capacitance and (e) capacitance retention plots for 5000 charge/discharge cycles at 5.0 A/g. (f) Energy density vs. power density plots of the Ni foam EDLC electrodes prepared in this study and some previously reported EDLC electrodes [<a href="#B24-metals-14-00354" class="html-bibr">24</a>,<a href="#B25-metals-14-00354" class="html-bibr">25</a>,<a href="#B26-metals-14-00354" class="html-bibr">26</a>]. Full article ">Figure 7
(a) EIS profiles and (b) enlarged EIS views for the EDLC electrodes. (c) Schematic illustration of interfacial charge transport with cross-sectional views for all EDLC electrodes. Full article ">Figure 8
(a) Photographs of symmetric EDLC electrodes in the straight and bent states, and (b,c) gravimetric charge–discharge curves obtained at 0.2, 5, and 10 A/g for (b) bare Ni and (c) 40MP-Ni EDLC electrodes. (d) Specific capacitance plots according to the current density in the range of 0.2 to 10 A/g for bare Ni and 40MP-Ni EDLC electrodes. Full article ">

15 pages, 16225 KiB

Open AccessArticle

The Influence of Yttrium Content and Ceramic Crucible Materials on Desulfurization during Vacuum Induction Melting of DD5 Superalloys

by Fuwei Wang, Ying Cheng, Shoubin Zhang, Rui Zhang, Yanyun Sun, Kai Guan, Huarui Zhang and Hu Zhang

Metals 2024, 14(3), 353; https://doi.org/10.3390/met14030353 - 19 Mar 2024

Viewed by 1116

Abstract

In this study, the effect of adding different contents of yttrium (Y) during vacuum induction melting in Al₂O₃ and Y₂O₃ crucibles on the purification of DD5 alloys was investigated. The results show that the Y₂O [...] Read more.

In this study, the effect of adding different contents of yttrium (Y) during vacuum induction melting in Al₂O₃ and Y₂O₃ crucibles on the purification of DD5 alloys was investigated. The results show that the Y₂O₃ crucible exhibited great crucible stability and an excellent desulfurization effect when melting a Y-containing DD5 alloy. The S content of the alloy was reduced from 5.03 ppm to 1.36 ppm with the addition of 0.50 wt.% Y. Element Y combined with free S in the melt to form the YS phase, which was removed from the condensate shell and slag during the vacuum induction melting (VIM) process. Meanwhile, when the alloy was melted in the Y₂O₃ crucible with 0.50 wt.% Y addition, there was a reduction in S content from 2.77 ppm to 1.36 ppm compared to the Al₂O₃ crucible. Additionally, the loss of Y decreased from 0.12 wt.% to 0.05 wt.%. 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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14 pages, 7950 KiB

Open AccessArticle

Mechanical Properties and Fracture Toughness Prediction of Ductile Cast Iron under Thermomechanical Treatment

by Mohammed Y. Abdellah, Hamzah Alharthi, Rami Alfattani, Dhia K. Suker, H. M. Abu El-Ainin, Ahmed F. Mohamed, Mohamed K. Hassan and Ahmed H. Backar

Metals 2024, 14(3), 352; https://doi.org/10.3390/met14030352 - 19 Mar 2024

Cited by 1 | Viewed by 1449

Abstract

Temperature has a great influence on the mechanical properties of ductile cast iron or nodular cast iron. A thermomechanical treatment was carried out at various elevated temperatures of 450 °C, 750 °C and 850 °C using a universal testing machine with a tub [...] Read more.

Temperature has a great influence on the mechanical properties of ductile cast iron or nodular cast iron. A thermomechanical treatment was carried out at various elevated temperatures of 450 °C, 750 °C and 850 °C using a universal testing machine with a tub furnace. Specimens were held at these temperatures for 20 min to ensure a homogeneous temperature distribution along the entire length of the specimen, before a tensile load was applied. Specimens were deformed to various levels of uniform strain (0%, 25%, 50%, 75%, and 100%). These degrees of deformation were measured with a dial gauge attached to a movable cross plate. Three strain rates were used for each specimen and temperature:

1.8 \times 10^{- 4} s^{- 1}

,

9 \times 10^{- 4} s^{- 1}

and

4.5 \times 10^{- 3} s^{- 1}

. A simple analytical model was extracted based on the CT tensile test geometry and yield stress and a 0.2% offset strain to measure the fracture toughness (J_IC). To validate the analytical model, an extended finite element method (XFEM) was implemented for specimens tested at different temperatures, with a strain rate of

1.8 \times 10^{- 4} s^{- 1}

. The model was then extended to include the tested specimens at other strain rates. The results show that increasing strain rates and temperature, especially at 850 °C, increased the ductility of the cast iron and thus its formability. The largest percentage strains were 1 and 1.5 at a temperature of 750 °C and a strain rate of

1.8 \times 10^{- 4} s^{- 1}

and

9 \times 10^{- 4} s^{- 1},

respectively, and reached their maximum value of 1.7 and 2.2% at 850 °C and a strain rate of

9 \times 10^{- 4} s^{- 1}

and

4.5 \times 10^{- 3} s^{- 1},

respectively. In addition, the simple and fast analytical model is useful in selecting materials for determining the fracture toughness (J_IC) at various elevated temperatures and different strain rates. Full article

(This article belongs to the Special Issue Thermomechanical Treatment of Metals and Alloys—Second Edition)

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13 pages, 70513 KiB

Open AccessArticle

Coaxial Electrospinning of CoS_1.097@C Core–Shell Fibers Anode Material for High-Performance Sodium-Ion Batteries

by Hongming Chen, Yan Li and Dan Zhou

Metals 2024, 14(3), 351; https://doi.org/10.3390/met14030351 - 19 Mar 2024

Viewed by 997

Abstract

As an important component that affects the storage performance of sodium-ion batteries (SIBs), novel anode materials still need to be well explored. Herein, CoS_1.097@C core–shell fibers as anode material were designed via coaxial electrospinning, stabilization, and carbonization. Specially, CoS_1.097 powders [...] Read more.

As an important component that affects the storage performance of sodium-ion batteries (SIBs), novel anode materials still need to be well explored. Herein, CoS_1.097@C core–shell fibers as anode material were designed via coaxial electrospinning, stabilization, and carbonization. Specially, CoS_1.097 powders are distributed in the inner shell of carbon fibers, and sufficient pore spaces are present among themselves. The unique encapsulation structure, porous characteristics, and one-dimensional conductive carbon shell can enable the CoS_1.097@C core–shell fibers’ high initial specific capacity, excellent rate capability, and long cycle life. The initial charge and discharge capacities of the electrode at 50 mA g⁻¹ are 386.0 and 830.9 mAh g⁻¹, respectively. After 2000 cycles at 500 mA g⁻¹, the discharge capacity is 216.3 mAh g⁻¹. Even at 3000 mA g⁻¹, the rate capacity can be maintained at 83.3 mAh g⁻¹. Full article

(This article belongs to the Special Issue Design, Synthesis and Characterization of Metal Batteries—State-of-the-Art)

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14 pages, 10053 KiB

Open AccessArticle

Effect Mechanism of α-Ferrite Sustained Precipitation on High-Temperature Properties in Continuous Casting for Peritectic Steel

by Songyuan Ai, Yifan Li, Mujun Long, Haohao Zhang, Dengfu Chen, Huamei Duan, Danbin Jia and Bingzhi Ren

Metals 2024, 14(3), 350; https://doi.org/10.3390/met14030350 - 18 Mar 2024

Cited by 1 | Viewed by 995

Abstract

Exploring the mechanism of the α-ferrite precipitation process on high-temperature properties plays an important guiding role in avoiding slab cracks and effectively regulating quality. In this work, in situ observation of the α-ferrite sustained precipitation behavior for peritectic steel during the austenitic [...] Read more.

Exploring the mechanism of the α-ferrite precipitation process on high-temperature properties plays an important guiding role in avoiding slab cracks and effectively regulating quality. In this work, in situ observation of the α-ferrite sustained precipitation behavior for peritectic steel during the austenitic phase transition process has been investigated using high-temperature confocal scanning laser microscopy. Meanwhile, the high-temperature evolution of the phase fractions during the phase transition process was quantitatively analyzed based on the high-temperature expansion experiment using the peak separation method. Furthermore, the high-temperature properties variations of the casting slab during the α-ferrite sustained precipitation process were investigated with the Gleeble thermomechanical simulator. The results show that the film-like ferrite precipitated along the austenite grain boundaries at the initial stage of phase transition, then needle-like ferrite initiates rapid precipitation on film-like ferrite when the average thickness reaches 15~20 μm. Hot ductility reached a minimum at the ferrite phase fraction f_α = 10~15%, while high-temperature properties returned to a higher level after f_α > 40~45%. The appearance of a considerable amount of needle-like ferrite and grain refinement effectively improves the high-temperature properties with the α-ferrite precipitation process advances. Full article

(This article belongs to the Special Issue Remelting and Casting Processes in the Production of Metals and Alloys)

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12 pages, 5237 KiB

Open AccessArticle

Influence of Submerged Entry Nozzles on Fluid Flow, Slag Entrainment, and Solidification in Slab Continuous Casting

by Xingang Zhen, Shiheng Peng and Jiongming Zhang

Metals 2024, 14(3), 349; https://doi.org/10.3390/met14030349 - 18 Mar 2024

Cited by 1 | Viewed by 1133

Abstract

In this paper, the fluid flow, slag entrainment and solidification process in a slab mold were studied using physical modeling and numerical simulation. The effect of two types of submerged entry nozzles (SENs) was also studied. The results showed that the surface velocity [...] Read more.

In this paper, the fluid flow, slag entrainment and solidification process in a slab mold were studied using physical modeling and numerical simulation. The effect of two types of submerged entry nozzles (SENs) was also studied. The results showed that the surface velocity for type A SEN was larger than that using type B SEN. For type A SEN, the maximum surface velocity was 0.63 m/s and 0.56 m/s, and it was 0.20 m/s and 0.18 m/s for type B SEN. The larger shear effect on the top surface made the slag at narrow face impacted to the vicinity of 1/4 wide face, while the slag layer at the top surface was relatively stable for type B SEN. Increasing the immersion depth of SEN decreased the surface velocity and slag entrainment. For type A SEN, the thickness of the solidified shell at the narrow face of the mold outlet was thin (12.3 mm) and there was a risk of breakout. For type B SEN, the liquid steel with high temperature would flow to the meniscus and it was beneficial to the melting of the mold flux. The thickness of the solidified shell at the narrow face of the mold outlet was increased. Furthermore, the surface velocity was also increased and it was not recommended for high casting speed. Full article

(This article belongs to the Special Issue Inclusion Metallurgy (2nd Edition))

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19 pages, 25574 KiB

Open AccessArticle

Different Heat-Exposure Temperatures on the Microstructure and Properties of Dissimilar GH4169/IC10 Superalloy Vacuum Electron Beam Welded Joint

by Hualin Cai, Zhixuan Ma, Jiayi Zhang, Liang Qi, Jinbing Hu and Jiayi Zhou

Metals 2024, 14(3), 348; https://doi.org/10.3390/met14030348 - 18 Mar 2024

Viewed by 1029

Abstract

Vacuum electron-beam welding (EBW) was used to join the precipitation-strengthened GH4169 superalloy and a new nickel-based superalloy IC10 to fabricate the turbine blade discs. In this study, a solid solution (1050 °C/2 h for GH4169 and 1150 °C/2 h for IC10) and different [...] Read more.

Vacuum electron-beam welding (EBW) was used to join the precipitation-strengthened GH4169 superalloy and a new nickel-based superalloy IC10 to fabricate the turbine blade discs. In this study, a solid solution (1050 °C/2 h for GH4169 and 1150 °C/2 h for IC10) and different heat-exposure temperatures (650 °C, 750 °C, 950 °C and 1050 °C/200 h, respectively) were used to study the high-temperature tensile properties and microstructure evolution of welded joints; meanwhile, the formation and evolution of the second phases of the joints were analyzed. After EBW, the welded joint exhibited a typical nail morphology, and the fusion zone (FZ) consisted of columnar and cellular structures. During the solidification process of the molten pool, Mo elements are enriched in the dendrites and inter-dendrites, and that of Nb and Ti elements was enriched in the dendrites, which lead to forming a non-uniform distribution of Laves eutectic and MC carbides in the FZ. The microhardness of the FZ gradually increased during thermal exposure at 650 °C and reached 300–320 HV, and the γ′ and γ″ phases were gradually precipitated with size of about 50 nm. Meanwhile, the microhardness of the FZ decreased to 260–280 HV at 750 °C, and the higher temperature resulted in the coarsening of the γ″ phase (with a final size of about 100 nm) and the formation of the acicular δ-phase. At 950 °C and 1050 °C, the microhardness of FZ decreased sharply, reaching up to 170~190 HV and 160~180 HV, respectively. Moreover, the Laves eutectic and MC carbides are dissolved to a greater extent without the formation of γ″ and δ phases; as a result, the absent of γ″ and δ phases are attributed to the significant improvement of segregation at higher temperatures. Full article

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14 pages, 28826 KiB

Open AccessArticle

Laser Remelting of Ductile Cast Iron to Achieve a Graphite-Free Surface Layer for Enabling a Manual High-Gloss Finish

by Laura Kreinest, Johannes Schüssler, Onur Özaydin, Sujith Kochuthundil Subhash, Edgar Willenborg and Andreas Bührig-Polaczek

Metals 2024, 14(3), 347; https://doi.org/10.3390/met14030347 - 18 Mar 2024

Viewed by 1105

Abstract

Laser remelting is being explored as a viable technique for obtaining a graphite-free, defect-free surface layer on cast iron EN GJS 400-15. The goal is to obtain a large remelted layer along with a low surface roughness to enable a subsequent manual high-gloss [...] Read more.

Laser remelting is being explored as a viable technique for obtaining a graphite-free, defect-free surface layer on cast iron EN GJS 400-15. The goal is to obtain a large remelted layer along with a low surface roughness to enable a subsequent manual high-gloss surface finish. The impact of the laser remelting process parameters is evaluated by using samples with three different cooling rates, resulting in different graphite microstructures. By utilizing four passes and a laser power of 300 W, the smallest roughness and largest remelting depth are achieved. The remelted layer is mostly devoid of graphite particles. Subsequent manual polishing is performed to evaluate the potential for achieving a high-gloss finish with a roughness of Sa < 0.05 µm. Laser remelting alone does not improve visual appearance or reduce roughness. However, after manual polishing, the roughness of the laser-remelted surfaces with Sa = 0.018 µm is one order of magnitude smaller than the manually polished initial state. Graphite removal during laser remelting therefore makes it possible to achieve a conventional and high-gloss polish, overcoming the previous limitations of GJS materials. Full article

(This article belongs to the Topic Laser Processing of Metallic Materials)

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20 pages, 17699 KiB

Open AccessFeature PaperArticle

Effect of Hydrogen on Fatigue Life and Fracture Morphologies of TRIP-Aided Martensitic Steels with Added Nitrogen

by Tomohiko Hojo, Akihiko Nagasaka, Junya Kobayashi, Yuki Shibayama and Eiji Akiyama

Metals 2024, 14(3), 346; https://doi.org/10.3390/met14030346 - 17 Mar 2024

Viewed by 1120

Abstract

The effects of hydrogen on the tensile properties, fatigue life, and tensile and fatigue fracture morphologies of nitrogen-added ultrahigh-strength transformation-induced plasticity (TRIP)-aided martensitic (TM) steels were investigated. The total elongation and number of cycles to failure (N_f) of the hydrogen-charged [...] Read more.

The effects of hydrogen on the tensile properties, fatigue life, and tensile and fatigue fracture morphologies of nitrogen-added ultrahigh-strength transformation-induced plasticity (TRIP)-aided martensitic (TM) steels were investigated. The total elongation and number of cycles to failure (N_f) of the hydrogen-charged TM steels decreased with the addition of nitrogen; in particular, adding 100 ppm of nitrogen decreased the total elongation and N_f of the TM steels. The quasi-cleavage cracking around the AlN occurred near the sample surface, which is the crack propagation region, although dimples appeared at the center of the fracture surface in the tensile samples. The initial fatigue crack initiated at the AlN precipitate or matrix/AlN interface, located at the notch root. During crack propagation, new cracks were initiated at the AlN precipitates or matrix/AlN interfaces, while quasi-cleavage crack regions were observed around the AlN precipitates. The decrease in the total elongation and N_f of the hydrogen-charged TM steel with 100 ppm of added nitrogen might be attributable to the crack initiation around the AlN precipitates formed by a large amount of hydrogen trapped at the AlN precipitates and matrix/AlN interfaces, and to the dense distribution of AlN, which promoted crack linkage. Full article

(This article belongs to the Special Issue Fatigue, Creep Behavior and Fracture Mechanics of Metals)

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15 pages, 4891 KiB

Open AccessArticle

Efficient Recovery of Lithium from Spent Lithium Ion Batteries Effluent by Solvent Extraction Using 2-Ethylhexyl Hydrogen {[Bis(2-Ethylhexyl) Amino]methyl} Phosphonate Acid

by Xiaoqin Wang, Zhulin Zhou, Xuting Si, Youcai Lu and Qingchao Liu

Metals 2024, 14(3), 345; https://doi.org/10.3390/met14030345 - 17 Mar 2024

Cited by 1 | Viewed by 1940

Abstract

In order to overcome the interface emulsification problem of TBP-FeCl₃ systems and the instability of β-diketone systems in high-concentration alkaline medium, it is necessary to design and synthesize some new extractants. By introducing amino groups into a phosphorus extractant, a new 2-ethylhexyl [...] Read more.

In order to overcome the interface emulsification problem of TBP-FeCl₃ systems and the instability of β-diketone systems in high-concentration alkaline medium, it is necessary to design and synthesize some new extractants. By introducing amino groups into a phosphorus extractant, a new 2-ethylhexyl hydrogen {[bis(2-ethylhexyl)amino]methyl} phosphonate acid (HA) extractant was synthesized. In this study, an efficient method of recovering lithium from the effluent of spent lithium-ion batteries (LIBs) is proposed. Experiments were conducted to assess the influential factors in lithium recovery, including the solution pH, saponification degree, extractant concentration, and phase ratio. Over 95% of lithium in the effluent was extracted into the organic phase, and nearly all lithium in the organic phase could be stripped into the aqueous phase using a 3 mol/L HCl solution. There was no significant decrease in extraction capacity after 10 cycles. The experimental results indicated that the extraction mechanism was a cation exchange process, and the extractive complex was proposed as LiA. Importantly, after three months of stable operation, the process demonstrated excellent stability and extraction efficiency, with rapid phase separation and a clear interface. This study offers an efficient, cost-effective, and environmentally friendly method for lithium extraction from the effluent of spent LIBs. Full article

(This article belongs to the Special Issue Advances in Sustainable Hydrometallurgy)

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15 pages, 15324 KiB

Open AccessArticle

Improved Discharge Performance of AZ72-0.05La Alloy Anode via Refining Mg₁₇Al₁₂ Phase

by Junqing Guo, Bo Wang and Shizhong An

Metals 2024, 14(3), 344; https://doi.org/10.3390/met14030344 - 17 Mar 2024

Viewed by 972

Abstract

The morphology of phases in magnesium alloys is vitally important for their performance. It is found that improved discharge performance is achieved in AZ72-0.05La alloy via a refining Mg₁₇Al₁₂ phase by means of hot rolling. Before rolling, as-cast AZ72-0.05La alloy [...] Read more.

The morphology of phases in magnesium alloys is vitally important for their performance. It is found that improved discharge performance is achieved in AZ72-0.05La alloy via a refining Mg₁₇Al₁₂ phase by means of hot rolling. Before rolling, as-cast AZ72-0.05La alloy has a relatively coarse and strip-like Mg₁₇Al₁₂ phase. After rolling, the Mg₁₇Al₁₂ phase becomes much finer, showing a granulated shape. Due to the refinement of the Mg₁₇Al₁₂ phase, the discharge voltage and energy density of an Mg-air battery with as-rolled AZ72-0.05La alloy as the anode increases by 6% and 3% under a discharge current density of 20 mA·cm⁻² in a 3.5% NaCl solution, respectively. The corrosion rate of the as-rolled AZ72-0.05La alloy is slightly larger than the as-cast AZ72-0.05La alloy, but still much lower than as-cast AZ72 alloy. The as-rolled AZ72-0.05La alloy possesses a discharge voltage of 0.74 V and an energy density of 918 mWh·g⁻¹ under a discharge current density of 20 mA·cm⁻², and a relatively low corrosion rate of 0.51 mg·cm⁻²·h⁻¹, demonstrating good overall discharge performance. This work provides a method for improving the discharge performance of Mg-air batteries. Full article

(This article belongs to the Special Issue New Horizons in Experimental Synthesis and Characterization of Advanced Metallic Nanomaterials and Nanocomposites for Energy Storage and Conversion)

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14 pages, 5024 KiB

Open AccessArticle

The Coupled Temperature Field Model of Difficult-to-Deform Mg Alloy Foil High-Efficiency Electro-Rolling and Experimental Study

by Gengliang Liu, Jiaxuan Yang, Tianren Shan, Huaimei Li, Dianlong Wang and Lipo Yang

Metals 2024, 14(3), 343; https://doi.org/10.3390/met14030343 - 17 Mar 2024

Viewed by 908

Abstract

In response to the challenging difficult-to-deform of magnesium foils, a high-efficiency and high-precision electro-rolling temperature field coupled model is established. This model is designed to simulate the non-annealing electric rolling (NAER) process of Mg foils under conditions of high current density, rapid temperature [...] Read more.

In response to the challenging difficult-to-deform of magnesium foils, a high-efficiency and high-precision electro-rolling temperature field coupled model is established. This model is designed to simulate the non-annealing electric rolling (NAER) process of Mg foils under conditions of high current density, rapid temperature rise rates, and large temperature gradients. Firstly, a coupled temperature field difference model for the guide roller, roll, and Mg foil is established, based on the equipment for NAER and the electrification conditions. The Joule heat, distortion heat, and friction heat in the electric rolling process were precisely considered. Secondly, considering the peculiarity of the heat source and the heat transfer mechanism during NAER, the influence of the dynamic boundary conditions on the instantaneous temperature of the Mg foil was analyzed, which was closer to the actual situation. The experimental results show that the original model can accurately simulate the transient temperature change in Mg foils during NAER, and the error between the predicted value and the measured value is within 7.1%. According to the calculation of the model, the microstructure of completely recrystallized magnesium foil with a grain size of 4.61 μm and a texture strength of 11.3 can be obtained at an inlet temperature of 250 °C. Full article

(This article belongs to the Special Issue Advances in Metal Rolling Processes)

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15 pages, 4580 KiB

Open AccessArticle

The Effects of Target Thicknesses and Backing Materials on a Ti-Cu Collision Weld Interface Using Laser Impact Welding

by Mohammed Abdelmaola, Brian Thurston, Boyd Panton, Anupam Vivek and Glenn Daehn

Metals 2024, 14(3), 342; https://doi.org/10.3390/met14030342 - 16 Mar 2024

Viewed by 1130

Abstract

This study demonstrates that the thickness of the target and its backing condition have a powerful effect on the development of a wave structure in impact welds. Conventional theories and experiments related to impact welds show that the impact angle and speed of [...] Read more.

This study demonstrates that the thickness of the target and its backing condition have a powerful effect on the development of a wave structure in impact welds. Conventional theories and experiments related to impact welds show that the impact angle and speed of the flyer have a controlling influence on the development of wave structure and jetting. These results imply that control of reflected stress waves can be effectively used to optimize welding conditions and expand the range of acceptable collision angle and speed for good welding. Impact welding and laser impact welding are a class of processes that can create solid-state welds, permitting the formation of strong and tough welds without the creation of significant heat affected zones, and can avoid the gross formation of intermetallic in dissimilar metal pairs. This study examined small-scale impact using a consistent launch condition for a 127 µm commercially pure titanium flyer impacted against commercially pure copper target with thicknesses between 127 µm and 1000 µm. Steel and acrylic backing layers were placed behind the target to change wave reflection characteristics. The launch conditions produced normal collision at about 900 m/s at the weld center, with decreasing impact speed and increasing angle moving toward the outer perimeter. The target thickness had a large effect on wave morphology, with the wave amplitude increasing with target thickness in both cases, peaking when target thickness is about twice flyer thickness, and then falling. The acrylic backing showed a consistently smaller unwelded central zone, indicating that impact welding is possible at a smaller angle in that case. Strength was measured in destructive tensile testing. Failure was controlled by the breakdown of the weaker of the two base metals over all thicknesses and backings. This demonstrates that laser impact welding is a robust method for joining dissimilar metals over a range of thicknesses. Full article

(This article belongs to the Special Issue Impact Welding Technology of Metal Alloys)

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25 pages, 6196 KiB

Open AccessArticle

Use of Electrochemical Noise for the Study of Corrosion by Passivated CUSTOM 450 and AM 350 Stainless Steels

by Facundo Almeraya-Calderon, Miguel Villegas-Tovar, Erick Maldonado-Bandala, Maria Lara-Banda, Miguel Angel Baltazar-Zamora, Griselda Santiago-Hurtado, Demetrio Nieves-Mendoza, Luis Daimir Lopez-Leon, Jesus Manuel Jaquez-Muñoz, Francisco Estupiñán-López and Citlalli Gaona-Tiburcio

Metals 2024, 14(3), 341; https://doi.org/10.3390/met14030341 - 16 Mar 2024

Cited by 4 | Viewed by 1111

Abstract

Precipitation-hardening stainless steels, like AM 350 and Custom 450, are extensively utilized in various aerospace applications. The latter steel is utilized for applications needing great strength and corrosion resistance. In contrast, the former steel has a good corrosion resistance and moderate strength. The [...] Read more.

Precipitation-hardening stainless steels, like AM 350 and Custom 450, are extensively utilized in various aerospace applications. The latter steel is utilized for applications needing great strength and corrosion resistance. In contrast, the former steel has a good corrosion resistance and moderate strength. The purpose of this study was to analyze transient frequencies in the electrochemical noise of Custom 450 and AM 350 stainless steels that had been passivated for 60 and 90 min at 25 and 49 °C using baths of citric and nitric acid and then immersed in solutions containing 1% sulfuric acid (H₂SO₄) and 5% sodium chloride (NaCl). The potentiodynamic polychromatic curves employed electrochemical techniques and noise (EN) based on the ASTM-G5 and G199 standards. Two methods of data analysis were applied concerning EN: the domain of frequencies (power spectral density, PSD) and the time–frequency domain (Hilbert-Huang Transform). The PHSS passivated in citric acid indicated current densities in the H₂SO₄ solution between 10⁻² and 10⁻³ mA/cm², while those in the NaCl solution were recorded around 10⁻⁴ and 10⁻⁵ mA/cm². The citric acid functions as a passivating agent. The results of the electrochemical noise analysis show that the PHSS passivated in nitric acid displayed a greater corrosion resistance. Moreover, there is a tendency for PHSS to be passivated in nitric acid to corrode locally. Full article

(This article belongs to the Special Issue Electrochemical Analysis of Metal Corrosion)

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13 pages, 3442 KiB

Open AccessArticle

Effect of Deformation Degree on Microstructure and Properties of Ni-Based Alloy Forgings

by Ruifeng Dong, Jian Li, Zishuai Chen, Wei Zhang and Xing Zhou

Metals 2024, 14(3), 340; https://doi.org/10.3390/met14030340 - 15 Mar 2024

Cited by 1 | Viewed by 997

Abstract

The primary objective of this paper is to investigate the influence of deformation degree on the microstructure and properties of a Ni-based superalloy. An upsetting experiment was conducted using a free-forging hammer to achieve a deformation degree ranging from 60% to 80%. The [...] Read more.

The primary objective of this paper is to investigate the influence of deformation degree on the microstructure and properties of a Ni-based superalloy. An upsetting experiment was conducted using a free-forging hammer to achieve a deformation degree ranging from 60% to 80%. The impact of the forging deformation degree on the hardness and high-temperature erosion performance was evaluated using the Rockwell hardness tester (HRC) and high-temperature erosion tester, respectively. The experimental results indicate that as the deformation degree increased, the hardness of the forged material progressively increased while the rate of high-temperature erosion gradually decreased. In order to comprehensively study the mechanism behind the variations in forging performance, optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) were employed. The findings reveal that as the deformation degree increased, the presence of small-angle grain boundaries and an increase in grain boundary area contributed to enhanced hardness in the alloy forgings. Furthermore, it was discovered that grain boundaries with twin orientation promoted dynamic recrystallization during deformation, specifically through a discontinuous dynamic recrystallization mechanism. Additionally, the precipitated γ′ phase in the alloy exhibited particle sizes ranging from 40 to 100 nm. This particle size range resulted in a higher critical shear stress value and a more pronounced strengthening effect on the alloy. Full article

(This article belongs to the Topic Microstructure and Properties in Metals and Alloys, 2nd Volume)

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Metals, Volume 14, Issue 3 (March 2024) – 117 articles

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