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Metals, Volume 13, Issue 3 (March 2023) – 197 articles

Cover Story (view full-size image): Laser shock peening (LSP) was performed on 304L stainless steel, and the SCC properties were evaluated by the U-bend test in 42% MgCl2. LSP induced a residual compressive stress in the depth direction and a grain refinement and an increased pitting potential of the cross section, and thus, total and net crack propagation rates were reduced. Based on the multiple regression analysis, the relationship between residual stress and crack propagation rates was strong, but the relationships between average grain size or pitting potential of the cross section and crack propagation rates were moderate or weak, respectively. View this paper
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13 pages, 54324 KiB  
Article
Influence of Precipitation Hardening on the Mechanical Properties of Co-Cr-Mo and Co-Cr-W-Mo Dental Alloys
by Marko Sedlaček, Katja Zupančič, Barbara Šetina Batič, Borut Kosec, Matija Zorc and Aleš Nagode
Metals 2023, 13(3), 637; https://doi.org/10.3390/met13030637 - 22 Mar 2023
Cited by 3 | Viewed by 1681
Abstract
Co-Cr alloys have good mechanical properties such as high hardness, excellent magnetic properties and good corrosion resistance. For this reason, they are most commonly used as dental and orthopaedic implants. Generally, cast Co-Cr-Mo alloys and forged Co-Ni-Cr-Mo alloys are used for the production [...] Read more.
Co-Cr alloys have good mechanical properties such as high hardness, excellent magnetic properties and good corrosion resistance. For this reason, they are most commonly used as dental and orthopaedic implants. Generally, cast Co-Cr-Mo alloys and forged Co-Ni-Cr-Mo alloys are used for the production of implants. In this study, we investigated two dental alloys, namely, Co-Cr-Mo and Co-Cr-W-Mo alloys. The aim of this study was to determine the effect of heat treatment on the development of the microstructure and to evaluate its influence on the alloys’ mechanical and tribological properties. The samples were first solution-annealed at 1200 °C in an argon atmosphere for 2 h, then quenched in water and subsequently aged at 900 °C in an argon atmosphere for 1, 3 and 12 h. A microstructural analysis was performed using SEM, with EDS for microchemical analysis and EBSD for phase identification. In addition, the Vickers hardness and wear resistance of the two alloys were analysed before and after heat treatment. The Co-Cr-Mo alloy showed better wear resistance and also a generally higher hardness than the Co-Cr-W-Mo alloy. Both alloys showed signs of abrasive and adhesive wear, with carbide particles detaching from the Co-Cr-W-Mo alloy due to the lower hardness of the matrix. The Co-Cr-Mo alloy showed the best abrasion resistance after the longest aging time (12 h), while the Co-Cr-W-Mo alloy showed the best as-cast abrasion resistance. With ageing, the wear resistance of both alloys increased. Full article
(This article belongs to the Special Issue Failure and Degradation of Metals)
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20 pages, 3295 KiB  
Article
Fatigue Life Assessment of Metals under Multiaxial Asynchronous Loading by Means of the Refined Equivalent Deformation Criterion
by Daniela Scorza
Metals 2023, 13(3), 636; https://doi.org/10.3390/met13030636 - 22 Mar 2023
Cited by 2 | Viewed by 1253
Abstract
As is well-known, non-proportional fatigue loading, such as asynchronous one, can have significant detrimental effects on the fatigue behavior of metallic materials by reducing the fatigue strength/fatigue limit and by leading to a fatigue damage accumulation increased with respect to that under proportional [...] Read more.
As is well-known, non-proportional fatigue loading, such as asynchronous one, can have significant detrimental effects on the fatigue behavior of metallic materials by reducing the fatigue strength/fatigue limit and by leading to a fatigue damage accumulation increased with respect to that under proportional loading. In the present paper, the novel refined equivalent deformation (RED) criterion is applied for the first time to estimate the fatigue lifetime of materials, sensitive to non-proportionality, subjected to asynchronous loading under low-cycle fatigue regime. The present criterion is complete since it considers: (i) the strain path orientation, (ii) the degree of non-proportionality, and (iii) the changing of material cyclic properties under non-proportional loading. To evaluate its accuracy, this criterion is applied to examine two different metals (a 304 stainless steel and a 355 structural steel) whose experimental data under multiaxial asynchronous loading are available in the literature. More precisely, the parameters of the criterion are firstly determined by using experimental strain paths, and then the computed refined equivalent deformation amplitude is used to represent the experimental data with a satisfactory accuracy. Finally, a comparison with the results obtained through two other criteria available in the literature is performed, highlighting the good prediction of the present RED criterion. Full article
(This article belongs to the Special Issue Fatigue Behavior and Crack Mechanism of Metals and Alloys)
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13 pages, 1962 KiB  
Article
Design Optimization of Chute Structure Based on E-SVR Surrogate Model
by Xiaoke Li, Qianlong Jiang, Yu Long, Zhenzhong Chen, Wenbo Zhao, Wuyi Ming, Yang Cao and Jun Ma
Metals 2023, 13(3), 635; https://doi.org/10.3390/met13030635 - 22 Mar 2023
Cited by 1 | Viewed by 1612
Abstract
To reduce the wear and damage of the chute caused by long-term impact of coke, a structure parameter optimization model was established in this paper, which takes the minimum impact force as the objective and the coke-conveying speed as the constraint. Furthermore, the [...] Read more.
To reduce the wear and damage of the chute caused by long-term impact of coke, a structure parameter optimization model was established in this paper, which takes the minimum impact force as the objective and the coke-conveying speed as the constraint. Furthermore, the ensemble of support vector regression (E-SVR) with different kernel functions was developed to replace the implicit relationship between the conveying speed, the impact force, and the structure parameters. Using the numerical examples, the effectiveness of the E-SVR model was verified. Finally, the optimal chute structure parameters were obtained by using the E-SVR model. After optimization, the maximum impact force was reduced by 17.07% and the maximum conveying speed was reduced by 6.59%, which still falls within the specified range. Therefore, the feasibility of the optimization results and the effectiveness of the E-SVR surrogate model were verified. Full article
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16 pages, 31830 KiB  
Article
Effect of Scanning Strategies on the Microstructure and Mechanical Properties of Ti-22Al-25Nb Alloy Fabricated through Selective Laser Melting
by Yaqun Liu, Zhongde Shan, Xujing Yang, Haowen Jiao and Weiying Huang
Metals 2023, 13(3), 634; https://doi.org/10.3390/met13030634 - 22 Mar 2023
Cited by 2 | Viewed by 1424
Abstract
In this study, Ti-22Al-25Nb intermetallic compound alloys are fabricated through selective laser melting (SLM) at four scanning speeds (600, 700, 800, and 900 mm/s). The microstructure and mechanical properties of the selective laser melting fabricated alloys are systematically evaluated. The results indicate that [...] Read more.
In this study, Ti-22Al-25Nb intermetallic compound alloys are fabricated through selective laser melting (SLM) at four scanning speeds (600, 700, 800, and 900 mm/s). The microstructure and mechanical properties of the selective laser melting fabricated alloys are systematically evaluated. The results indicate that scanning speed significantly affects microstructure characteristics (e.g., relative density, grain size, texture density, and the precipitation of secondary phases). The variation laws of the relative density, grain size, and texture density are likewise affected by scanning speed. The relative density, grain size, and texture density increase and then decrease with the increase in scanning speed. The alloy fabricated with the lowest scanning speed (600 mm/s) exhibits the maximum relative density, grain size, and texture density. By contrast, the alloy with the highest scanning speed (900 mm/s) exhibits the minimum relative density, grain size, and texture density. Furthermore, the precipitations of the O phase and Ti3Al phase are primarily distributed in regions with a high strain concentration near the pool boundary. The alloy fabricated with a 600 mm/s scanning speed simultaneously achieves the highest strength and elongation, which is closely correlated with the uniform distribution of secondary phases. Full article
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28 pages, 6681 KiB  
Article
Interpolation and Extrapolation Performance Measurement of Analytical and ANN-Based Flow Laws for Hot Deformation Behavior of Medium Carbon Steel
by Pierre Tize Mha, Prashant Dhondapure, Mohammad Jahazi, Amèvi Tongne and Olivier Pantalé
Metals 2023, 13(3), 633; https://doi.org/10.3390/met13030633 - 22 Mar 2023
Cited by 5 | Viewed by 2258
Abstract
In the present work, a critical analysis of the most-commonly used analytical models and recently introduced ANN-based models was performed to evaluate their predictive accuracy within and outside the experimental interval used to generate them. The high-temperature deformation behavior of a medium carbon [...] Read more.
In the present work, a critical analysis of the most-commonly used analytical models and recently introduced ANN-based models was performed to evaluate their predictive accuracy within and outside the experimental interval used to generate them. The high-temperature deformation behavior of a medium carbon steel was studied over a wide range of strains, strain rates, and temperatures using hot compression tests on a Gleeble-3800. The experimental flow curves were modeled using the Johnson–Cook, Modified-Zerilli–Armstrong, Hansel–Spittel, Arrhenius, and PTM models, as well as an ANN model. The mean absolute relative error and root-mean-squared error values were used to quantify the predictive accuracy of the models analyzed. The results indicated that the Johnson–Cook and Modified-Zerilli–Armstrong models had a significant error, while the Hansel–Spittel, PTM, and Arrhenius models were able to predict the behavior of this alloy. The ANN model showed excellent agreement between the predicted and experimental flow curves, with an error of less than 0.62%. To validate the performance, the ability to interpolate and extrapolate the experimental data was also tested. The Hansel–Spittel, PTM, and Arrhenius models showed good interpolation and extrapolation capabilities. However, the ANN model was the most-powerful of all the models. Full article
(This article belongs to the Special Issue Hot Deformation of Metal and Alloys)
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12 pages, 4748 KiB  
Article
Effect of Semi-Aging Heat Treatment on Microstructure and Mechanical Properties of an Inertia Friction Welded Joint of FGH96 Powder Metallurgy Superalloy
by Xiufeng Han, Guoliang Zhu, Qingbiao Tan and Baode Sun
Metals 2023, 13(3), 632; https://doi.org/10.3390/met13030632 - 22 Mar 2023
Cited by 3 | Viewed by 1568
Abstract
Inertia friction welded joints often present different microstructures than the base metal, and subsequent heat treatment processes are always needed to maintain superior performance. This study investigates the effect of semi-aging heat treatment after welding on the microstructure, residual stress, micro-hardness, and tensile [...] Read more.
Inertia friction welded joints often present different microstructures than the base metal, and subsequent heat treatment processes are always needed to maintain superior performance. This study investigates the effect of semi-aging heat treatment after welding on the microstructure, residual stress, micro-hardness, and tensile properties of inertia friction welded FGH96 powder metallurgy superalloy using optical microscopy, scanning electron microscopy, X-ray diffraction, and hardness and tensile tests. The results show that the semi-aging heat treatment after welding does not affect the grain size or grain morphology of the base metal. However, the recrystallization process can be further promoted in the weld nugget zone and transition zone. Meanwhile, the grain size is refined and the residual stress is significantly reduced in the welded joint after the same heat treatment. Under the synergetic strengthening effect of the γ′ phase, semi-aging heat treatment increased the micro-hardness of the weld nugget zone from 470 HV to 530 HV and improved the average tensile strength at room temperature by 118 MPa. These findings provide a reference for the selection of the heat treatment process after inertia friction welding of nickel-based powder metallurgy superalloys. Full article
(This article belongs to the Section Welding and Joining)
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11 pages, 2703 KiB  
Communication
Research Regarding Molybdenum Flakes’ Improvement on the Hydrogen Storage Efficiency of MgH2
by Changshan Cheng, Haoyu Zhang, Mengchen Song, Fuying Wu and Liuting Zhang
Metals 2023, 13(3), 631; https://doi.org/10.3390/met13030631 - 22 Mar 2023
Cited by 2 | Viewed by 1288
Abstract
As an efficient hydrogen storage material, magnesium hydride (MgH2) has a high capacity of 7.6 wt%. However, its performance deteriorates because of high thermodynamic and kinetic temperatures and the fast agglomeration of its nanocrystals during the hydrogen uptake and release process. [...] Read more.
As an efficient hydrogen storage material, magnesium hydride (MgH2) has a high capacity of 7.6 wt%. However, its performance deteriorates because of high thermodynamic and kinetic temperatures and the fast agglomeration of its nanocrystals during the hydrogen uptake and release process. The exploration of efficient catalysts is a popular, but currently challenging, topic. Therefore, we successfully prepared flake-like molybdenum (Mo) catalysts and doped them into MgH2 to enhance its properties. We found that the incorporation of 7wt%Mo into MgH2 could reduce the starting desorption temperature by approximately 100 °C. In addition, the 7wt%Mo-doped MgH2 could desorb almost all of the H2 within 20 min at a 325 °C isothermal condition. For hydrogenation, MgH2-7wt%Mo could absorb approximately 5 wt% of hydrogen within 5 min at a 250 °C isothermal condition with a hydrogen pressure of 3 MPa. In addition, the MgH2-7wt%Mo composite could maintain approximately 98% of the initial capacity at the end of 22 cycles, presenting good cycling performance. Full article
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12 pages, 2381 KiB  
Article
Effect of Annealing and Hot Isostatic Pressing on the Structure and Hydrogen Embrittlement Resistance of Powder-Bed Fusion-Printed CoCrFeNiMn High-Entropy Alloys
by Shulu Feng, Zhijiu Ai, Jiayi He, Bangjian Yang, Guoqing Gou and Lei Han
Metals 2023, 13(3), 630; https://doi.org/10.3390/met13030630 - 22 Mar 2023
Cited by 2 | Viewed by 1650
Abstract
As an additive-manufacturing (AM) technique, powder-bed fusion (PBF) shows tremendous potential in both the research and industrial communities. Research on the post-treatment of PBF-prepared products is a hot topic. Hydrogen embrittlement (HE) resistance is a practical necessity, especially in microstructures. Here, the effect [...] Read more.
As an additive-manufacturing (AM) technique, powder-bed fusion (PBF) shows tremendous potential in both the research and industrial communities. Research on the post-treatment of PBF-prepared products is a hot topic. Hydrogen embrittlement (HE) resistance is a practical necessity, especially in microstructures. Here, the effect of annealing and hot isostatic pressing (HIP) on the properties of PBF technology-printed CoCrFeNiMn high-entropy alloys (HEAs) is investigated. The results show that these two post-thermal treatment approaches can release residual stress (from approximately 338 to 44 MPa) from PBF-printed samples, which is the main reason for declines in hardness (from approximately 211 to 194 HV). In addition, both annealing and HIP can reduce HE sensitivity, thus improving resistance to HE, with elongation increasing by 75.4% and 85.4% after annealing and HIP, respectively. In summary, both post-thermal treatments are of great significance to the development of HEAs with optimized structures and protection against HE, which can contribute to the development of these behaviors during application. Full article
(This article belongs to the Special Issue Progress in Laser Additive Manufacturing on Metal Material)
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15 pages, 5599 KiB  
Article
An Improved Multiaxial Low-Cycle Fatigue Life Prediction Model Based on Equivalent Strain Approach
by Peng-Nian Zhu, Jian-Xiong Gao, Yi-Ping Yuan, Zhi-Feng Wu and Rong-Xia Xu
Metals 2023, 13(3), 629; https://doi.org/10.3390/met13030629 - 21 Mar 2023
Cited by 3 | Viewed by 1694
Abstract
The fatigue life of the materials is significantly reduced under non-proportional loading. In this study, the factors affecting additional hardening are explored, and a hardening function is proposed. Firstly, the stress and strain states of the specimen under multiaxial loading are analyzed, and [...] Read more.
The fatigue life of the materials is significantly reduced under non-proportional loading. In this study, the factors affecting additional hardening are explored, and a hardening function is proposed. Firstly, the stress and strain states of the specimen under multiaxial loading are analyzed, and the deficiencies of the equivalent strain models are discussed. Secondly, the factors affecting the additional hardening are analyzed from both stress and strain perspectives, and the effect of phase differences on fatigue life is investigated. The stress on the critical plane is considered to reflect its effect on crack initiation and growth. An improved multiaxial low-cycle fatigue life prediction model is developed based on the equivalent strain approach. Finally, experimental data from five metals are used to verify the established model and are compared with existing classical models. The results show that the proposed model has good accuracy. Full article
(This article belongs to the Special Issue Fracture Mechanics of Metals)
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17 pages, 4137 KiB  
Article
First-Principles Investigation on Phase Stability, Mechanical Properties, Bonding Characteristic and Slip Properties of Ti-Co Binary Intermetallic Compounds
by Fanlin Zeng, Mengjie Chen, Hongbo Wang, Hexiang Peng, Bei Li and Jian Huang
Metals 2023, 13(3), 628; https://doi.org/10.3390/met13030628 - 21 Mar 2023
Viewed by 2790
Abstract
Ti-Co binary intermetallic compounds have attracted lots of attention due to their excellent toughness and interesting anomalous ductility. However, systematic theoretical calculations of alloy properties of different Ti-Co compounds have not been properly investigated yet. In this work, first-principles calculations were performed to [...] Read more.
Ti-Co binary intermetallic compounds have attracted lots of attention due to their excellent toughness and interesting anomalous ductility. However, systematic theoretical calculations of alloy properties of different Ti-Co compounds have not been properly investigated yet. In this work, first-principles calculations were performed to study the phase stability, mechanical properties bonding characteristic and slip properties of five Ti-Co binary compounds. The negative enthalpy of formation and cohesive energy showed that all the Ti-Co binary compounds were thermodynamically stable, and TiCo is the most mechanically stable one. According to the elastic stability criterion, these compounds are also mechanically stable. In addition, the mechanical anisotropy of Ti-Co compounds was analyzed by the anisotropy index and the three-dimensional surface of Young’s modulus, where Ti2Co shows the strongest anisotropy, and TiCo2(h) has weakest anisotropy. The phonon calculations of these compounds also show that all five Ti-Co compounds are thermodynamically stable. The density of states (DOS) and differential charge density distributions were analyzed to identify the chemical bonding characteristics of the Ti-Co binary compounds, which exhibit metal and covalent-like bonding and different magnetic properties. Finally, the plastic deformation mechanism of Ti-Co compounds was understood by calculating the generalized stacking fault energy (GSFE) of different slip systems. The anomalous ductility of TiCo and TiCo3 mainly arises from the complex slip system and the lower slip energy barrier of the compounds. Full article
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21 pages, 4074 KiB  
Article
Uptake of Silver by Jarosite and Natrojarosite Family Compounds at 22 °C, 97 °C and 140 °C
by Peter F. Cogram, Mark D. Welch and Karen A. Hudson-Edwards
Metals 2023, 13(3), 627; https://doi.org/10.3390/met13030627 - 21 Mar 2023
Cited by 1 | Viewed by 1389
Abstract
The jarosite family of minerals are part of the alunite supergroup with the general formula AB3(TO4)2(OH)6. Jarosite family minerals are known to incorporate silver (Ag), but the extent to which this occurs, and at what [...] Read more.
The jarosite family of minerals are part of the alunite supergroup with the general formula AB3(TO4)2(OH)6. Jarosite family minerals are known to incorporate silver (Ag), but the extent to which this occurs, and at what temperature range, is not well constrained. To address this knowledge gap, jarosite compounds with the A site filled with K, Na, Ag and H3O were synthesised at 22 °C, 97 °C and 140 °C to simulate low-, moderate- and high-temperature environments, respectively. The compounds were characterised by XRD, SEM, chemical analysis and Raman spectroscopy. All of the synthesised compounds took up Ag. In general, higher temperatures of synthesis increased alkali and Ag occupancy of the A site of the products. Silver contents increased with the increasing concentration of Ag in the starting solutions at all temperatures. The order of preference for occupancy of the A site in the synthesised solids is K > Na > H3O > Ag at all temperatures, which is consistent with the reported order of ΔGf of −3309 kJ/mol, −3270 kJ/mol, −3247 kJ/mol and −2948 kJ/mol for jarosite, natrojarosite, hydroniumjarosite and argentojarosite, respectively. The results of this study show that Ag can be incorporated in jarosite and natrojarosite at low-to-high temperatures, and therefore, jarosite family minerals can be important stores of Ag in in natural and engineered environments. Full article
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15 pages, 13733 KiB  
Article
Effects of Rare Earth La–Ce Alloying Treatment on Modification of Inclusions and Magnetic Properties of W350 Non-Oriented Silicon Steel
by Haijun Wang, Yuhao Niu, Haitao Ling, Jialong Qiao, Yanling Zhang, Wei Zhong and Shengtao Qiu
Metals 2023, 13(3), 626; https://doi.org/10.3390/met13030626 - 21 Mar 2023
Cited by 2 | Viewed by 1556
Abstract
In order to study the effects of rare earth La–Ce alloying treatment on the characteristics of inclusions in non-oriented silicon steels, industrial experiments were conducted studying the composition, morphology, size and quantity of inclusions in W350 non-oriented silicon steel during the RH (Ruhrstahl-Hereaeus) [...] Read more.
In order to study the effects of rare earth La–Ce alloying treatment on the characteristics of inclusions in non-oriented silicon steels, industrial experiments were conducted studying the composition, morphology, size and quantity of inclusions in W350 non-oriented silicon steel during the RH (Ruhrstahl-Hereaeus) refining process and tundish process, after rare earth treatment. The products were analyzed by means of ICP-MS (inductively coupled plasma mass spectrometry), SEM/EDS (scanning electron microscope-energy dispersive spectrometry), and ASPEX (automated SEM/EDS inclusion analysis). The research results showed that the types of inclusions in experimental steel changed significantly after rare earth treatment. The types of inclusions after RE (rare earth) treatment are typically rare earth composite inclusions that are mainly composed of (La, Ce)Al2O3, and conventional inclusions. The addition of rare earth promotes the agglomeration of inclusions; the morphologies of the inclusions are mostly blocky, and some are distributed in long strips. After rare earth treatment during the RH refining process, the number of inclusions with sizes of 1.0~3.5 μm in the experimental steel is increased, and the average size of the inclusions is 2.66 μm. In addition, the number of inclusions larger than 4 μm in the specimens increases due to the collision and growth of inclusions caused by the RH circulation. After rare earth treatment during the tundish process, the number of micro inclusions with sizes of 1.0~2.5 μm in the specimen steels decreases, while the number of inclusions larger than 5 μm increases. The size distribution of micro inclusions in hot-rolled sheets after rare earth treatment was studied using TEM (transmission electron microscopy). In the specimens without rare earth, the content of micro inclusions (≤1 μm) is 51,458.2/mm2 and the average size is 0.388 μm. In the specimens with rare earth added, the content of micro inclusions (≤1 μm) is 24,230.2/mm2 and the average size is 0.427 μm. Compared to sheet produced by the original process, the iron loss of the 0.35 mm finished experimental sheet is reduced by 0.068 W/kg, and the magnetic induction is increased by 0.007 T. The iron loss of the 0.50 mm finished experimental sheet is reduced by 0.008 W/kg, and the magnetic induction is increased by 0.004 T. After rare earth treatment, the average size of micro inclusions increases and the magnetic properties are obviously improved. Full article
(This article belongs to the Special Issue Inclusion Metallurgy)
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13 pages, 9237 KiB  
Article
Distinguishing Features of Quenched Nanoprecipitates in Allotriomorphic Ferrite and Reverted γ during Aging for Dual-Phase PHSS
by Ping-Jui Yu, Tzu-Ching Tsao, Cheng-An Hsu, Neng-Hao Gan, Shing-Hoa Wang, Jer-Ren Yang, Horng-Yi Chang and Tsai-Fu Chung
Metals 2023, 13(3), 625; https://doi.org/10.3390/met13030625 - 21 Mar 2023
Cited by 1 | Viewed by 1452
Abstract
A novel dual-phase PHSS consisting of lath martensite plus allotriomorphic δ ferrite (ALF) with nanoprecipitates was characterized by high-resolution field emission transmission electron microscopy for quenched, solid-solution-treated, and aged stainless steel. The effects of aging at various durations prior to H2O [...] Read more.
A novel dual-phase PHSS consisting of lath martensite plus allotriomorphic δ ferrite (ALF) with nanoprecipitates was characterized by high-resolution field emission transmission electron microscopy for quenched, solid-solution-treated, and aged stainless steel. The effects of aging at various durations prior to H2O or liquid N2 quenching were investigated. Cu-rich nanoprecipitates evolve from body-centered cubic clusters to 9R Cu under quenching to 3R Cu and subsequently to face-centered cubic ε-Cu at various aging durations. Maximum hardness was observed after aging at 600 °C for 1 h. However, after this aging, both reversed austenite and Cu-rich nanoprecipitates coexisted in the martensite matrix. The segregation and diffusion of austenite-stabilizing elements promoted the nucleation of reversed austenite. Full article
(This article belongs to the Special Issue Microstructural Characterization of Metallic Materials)
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14 pages, 10782 KiB  
Article
Influence of the Dross Formation of the Laser-Cut Edge on the Fatigue Strength of AISI 304
by Julia Bach, André T. Zeuner, Thomas Wanski, Sarah C. L. Fischer, Patrick Herwig and Martina Zimmermann
Metals 2023, 13(3), 624; https://doi.org/10.3390/met13030624 - 20 Mar 2023
Viewed by 1854
Abstract
Laser cutting is a thermal cutting process based on material melting that results in characteristic features of the cut edge. The dross in particular is a crucial quality-determining feature which occurs especially when processing higher sheet thicknesses. The influence of the dross geometry [...] Read more.
Laser cutting is a thermal cutting process based on material melting that results in characteristic features of the cut edge. The dross in particular is a crucial quality-determining feature which occurs especially when processing higher sheet thicknesses. The influence of the dross geometry on the fatigue behavior of AISI 304 was investigated in this work. Using iterative experimental design, samples with different dross geometries were produced by varying laser cutting parameters. Four characteristic dross geometries were identified and used to classify manufacturing parameters: dross-free, small droplets, large droplets and very coarse dross. Fatigue tests were performed up to 107 load cycles and revealed a dependence of the fatigue behavior on the dross geometries due to their different notch effects. It was found that the dross dominated the fatigue strength only above a certain dross height. At low dross heights, the surface relief of the cut edge dominated fatigue strength. The different cut edge properties (surface relief and dross) depend on the process parameters during laser cutting. Gas pressure and feed rate in particular showed a significant influence. The findings of this work provide information about the fatigue behavior’s dependence on dross geometry, which can be transferred to higher sheet thicknesses or complex sample geometries. Full article
(This article belongs to the Special Issue Laser-Assisted Processing of Metals and Alloys)
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14 pages, 6364 KiB  
Article
Monte-Carlo-Assisted Phase Field Simulations of Grain Structure Evolution during the Welding Process
by Ying Zheng, Jiangping Liu, Yongfeng Liang and Pingping Wu
Metals 2023, 13(3), 623; https://doi.org/10.3390/met13030623 - 20 Mar 2023
Cited by 1 | Viewed by 1563
Abstract
A Monte-Carlo-assisted phase field model for the simulation of grain growth in metals and alloys is presented. The simulation time in this model is connected to real time through an experimental data-based kinetic model. Site selection probability is introduced to simulate grain structure [...] Read more.
A Monte-Carlo-assisted phase field model for the simulation of grain growth in metals and alloys is presented. The simulation time in this model is connected to real time through an experimental data-based kinetic model. Site selection probability is introduced to simulate grain structure evolution under non-isothermal conditions. The grain evolutions with temporal and spatial distributions of temperature during the welding process are comprehensively reproduced. The average size and topological texture of the generated grains in the fusion zone and heat-affected zone are examined. The computed results are compared to experimental data for laser-welding two alloys: Fe–6.5 wt.%Si and low-carbon steel. The applications of real-time–temperature based phase field simulation to material processing indicate significant promise for understanding grain structures during the welding process or additive manufacturing processes. Full article
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15 pages, 11287 KiB  
Article
Production of Refined and Modified Closed-Cell Aluminum Foams by Melt-Foaming Method
by Alberto Jesús Poot Manzanilla, Alejandro Cruz Ramírez, Eduardo Colin García, José Antonio Romero Serrano, Ricardo Gerardo Sánchez Alvarado and Miguel Ángel Suárez Rosales
Metals 2023, 13(3), 622; https://doi.org/10.3390/met13030622 - 20 Mar 2023
Cited by 2 | Viewed by 1605
Abstract
Closed-cell A356 aluminum alloy foams refined and modified were successfully fabricated by using barite and calcium carbonate as thickening and foaming agents, respectively. A melt treatment consisting of adding master alloys of Al-5Ti-1B and Al-10Sr for refining the dendritic microstructure and modifying the [...] Read more.
Closed-cell A356 aluminum alloy foams refined and modified were successfully fabricated by using barite and calcium carbonate as thickening and foaming agents, respectively. A melt treatment consisting of adding master alloys of Al-5Ti-1B and Al-10Sr for refining the dendritic microstructure and modifying the primary eutectic silicon, respectively, were included in the foaming process. The microstructure and mechanical properties of the foams manufactured were analyzed and compared with foams produced without the refining and modifying treatments. The secondary dendritic arm spacing (SDAS) was determined by optical measurements. Lower SDAS values were obtained in foam regions closer to the mold walls due to the high solidification rate imposed during the cooling step and a decrease in the SDAS values for the foams produced with the addition of the Al-5Ti-1B master alloy was evident. Additionally, the addition of the Al-10Sr master alloy caused the formation of solid solution dendrites and a fine irregular fibrous form of silicon. Foams produced with the melt treatment exhibit a good combination of structure and mechanical properties. Therefore, the melt route established is a feasible way to improve foam performance where the lowest SDAS and the highest mechanical properties were obtained for the closed-cell foams produced. Full article
(This article belongs to the Special Issue Advanced Metallic Foams)
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17 pages, 4116 KiB  
Article
Open-Access Experiment Dataset for Fatigue Damage Accumulation and Life Prediction Models
by Kris Hectors, Dennis Vanspeybrouck, Jelle Plets, Quinten Bouckaert and Wim De Waele
Metals 2023, 13(3), 621; https://doi.org/10.3390/met13030621 - 20 Mar 2023
Cited by 3 | Viewed by 1795
Abstract
This work addresses the lack of focus on verification and comparison of existing fatigue damage accumulation and life prediction models on the basis of large and well-documented experiment datasets. Sixty-four constant amplitude, 54 two-level block loading, and 27 three-level block loading valid experiments [...] Read more.
This work addresses the lack of focus on verification and comparison of existing fatigue damage accumulation and life prediction models on the basis of large and well-documented experiment datasets. Sixty-four constant amplitude, 54 two-level block loading, and 27 three-level block loading valid experiments were performed in order to generate an open-access, high-quality dataset that can be used as a benchmark for existing models. In the future, more experiments of various specimen geometries and loading conditions will be added. The obtained dataset was used for a study comparing five (non)linear fatigue damage and life prediction models. It is shown how the performance of several (non)linear damage models is strongly dependent on the considered material dataset and loading sequence. Therefore, it is important to verify models with a broad set of independent datasets, as many existing models show significant bias to certain datasets. Full article
(This article belongs to the Section Metal Failure Analysis)
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13 pages, 5170 KiB  
Article
Effect of Process Parameters on Spinning Force and Forming Quality of Deep Cylinder Parts in Multi-Pass Spinning Process
by Libo Li, Siyuan Chen, Qinying Lu, Xuedao Shu, Jun Zhang and Weiwei Shen
Metals 2023, 13(3), 620; https://doi.org/10.3390/met13030620 - 20 Mar 2023
Cited by 6 | Viewed by 1670
Abstract
In this paper, based on MSC Simufact.Forming v16.0 simulation software, the process parameters in the multi-pass spinning production of deep cylinders with a large diameter–thickness ratio are optimized, and the ten-pass spinning process of a deep cylinder with a diameter of 500 mm, [...] Read more.
In this paper, based on MSC Simufact.Forming v16.0 simulation software, the process parameters in the multi-pass spinning production of deep cylinders with a large diameter–thickness ratio are optimized, and the ten-pass spinning process of a deep cylinder with a diameter of 500 mm, thickness of 2 mm and depth of 700 mm is realized. By controlling the four process parameters of mandrel speed, feed rate, spinning wheel fillet radius and spinning wheel angle of attack, the influence of the four process parameters on the spinning force and the wall thickness deviation of the formed workpiece is studied. The results show that the radial spinning force and tangential spinning force are at their minimum when the mandrel speed, feed rate, spinning wheel fillet radius and spinning wheel angle of attack are 500 rpm, 1 mm/rev, 6 mm and 35°, respectively. At these setup conditions, the spinning efficiency is the highest and the workpiece is not prone to defects. The wall thickness deviation of the workpiece will decrease with the increase in the mandrel speed; with the increase in the feed rate, the radius of the round corner and spinning wheel angle of attack, the wall thickness deviation increases first and then decreases. Full article
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19 pages, 5508 KiB  
Article
Chip Morphology and Surface Integrity in Turning AZ31 Magnesium Alloy under Dry Machining and Submerged Convective Cooling
by Muhammad Syamil Zakaria, Mazli Mustapha, Azwan Iskandar Azmi and Chu Yee Khor
Metals 2023, 13(3), 619; https://doi.org/10.3390/met13030619 - 20 Mar 2023
Cited by 2 | Viewed by 1543
Abstract
Magnesium alloys have broad applications, including medical implants and the aerospace sector owing to their great density and high strength-to-weight ratio. Dry cutting is a frequent technique for machining this material. However, it always leads to an excessive rise in temperature due to [...] Read more.
Magnesium alloys have broad applications, including medical implants and the aerospace sector owing to their great density and high strength-to-weight ratio. Dry cutting is a frequent technique for machining this material. However, it always leads to an excessive rise in temperature due to the absence of cooling at the cutting zone, which affects the machined surface integrity and chip morphology. In this study, chip morphology and surface integrity of the AZ31 magnesium alloy were investigated in the turning process using an internal cooling method called submerged convective cooling (SCC) to overcome the absence of cooling in dry cutting. This method can exploit the advantage of the high specific heat capacity of water as a cooling fluid without any reaction between water and magnesium to create a cooling element in the cutting zone. The chip morphologies and surface integrity were analyzed experimentally with varying cutting speeds under SCC and dry cutting. The experimental results revealed that SCC and dry cutting produced saw-tooth or serrated chip formation. The chips produced in dry cutting were continuous, while SCC was short and discontinuous as a result of a severe crack on the back surface of the chip. It was discovered that the grain refinement layer on the machined samples was thinner under SCC turning. SCC machining increased the microhardness of the AZ31 magnesium alloy by 60.5% from 55 HV to 88.3 HV, while dry turning exhibited a 49% increase in microhardness. The result revealed that surface roughness improved by 10.8%, 9.4% and 4.7% for cutting speeds (V) of 120, 180, and 240 m/min, respectively, under the SCC internal cooling. Based on the result obtained, SCC cutting outperformed dry cutting in terms of chip breakability, grain refinement, microhardness, and surface roughness. Full article
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9 pages, 8167 KiB  
Communication
Effect of Strain Rate on Compressive Properties of Aluminium-Graphene Composites
by Yufu Yan, Jiamin Zhao, Long Chen, Hongjian Zhao, Olga Klimova-Korsmik, Oleg V. Tolochko, Fuxing Yin, Puguang Ji and Shaoming Kang
Metals 2023, 13(3), 618; https://doi.org/10.3390/met13030618 - 20 Mar 2023
Cited by 1 | Viewed by 1517
Abstract
Graphene-reinforced aluminium composites have been widely studied due to their excellent mechanical properties. However, only a few studies have reported their dynamic compression properties. The purpose of this study is to investigate the quasi-static and dynamic compression properties of graphene-reinforced aluminium composites. The [...] Read more.
Graphene-reinforced aluminium composites have been widely studied due to their excellent mechanical properties. However, only a few studies have reported their dynamic compression properties. The purpose of this study is to investigate the quasi-static and dynamic compression properties of graphene-reinforced aluminium composites. The addition of graphene improved the compressive stress resistance and energy absorption capacity of the aluminium matrix. An aluminium-0.5 wt.% graphene composite exhibited good compressive properties due to the different interfacial wave impedance generated by the additional grain boundaries or Aluminium-Graphene interfaces. Full article
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15 pages, 11347 KiB  
Article
Binder Jet Additive Manufacturing Process and Material Characterization for High Temperature Heat Exchangers Used in Concentrated Solar Power Applications
by William D. Gerstler, Ananda Barua, Shenyan Huang, Daniel J. Erno, Yongxiang Wang, Siyeong Ju and Naveenan Thiagarajan
Metals 2023, 13(3), 617; https://doi.org/10.3390/met13030617 - 19 Mar 2023
Cited by 4 | Viewed by 2112
Abstract
The U.S. Department of Energy’s (DOE) Sunshot 2030 initiative has a goal of reducing the cost of concentrating solar power (CSP) to 5 cents per kWh for baseload power plants. One of the potential pathways to this goal includes a reduction in the [...] Read more.
The U.S. Department of Energy’s (DOE) Sunshot 2030 initiative has a goal of reducing the cost of concentrating solar power (CSP) to 5 cents per kWh for baseload power plants. One of the potential pathways to this goal includes a reduction in the cost of the supercritical CO2 (sCO2) power block to 0.9 cents per kWh. Recuperators—high and low temperatures, used in the sCO2 power cycle, contribute to >50% of the cost of the power cycle. This work studies the feasibility towards a ≥10% cost reduction for High Temperature Recuperators (HTR) used in the sCO2 power cycle. One way to address the cost reduction is by leveraging low-cost additive manufacturing, specifically, Binder Jet Additive Manufacturing (BJAM) to 3D print HTRs at scale. This study focuses on the development of a BJAM process towards 3D printing HTR cores using Stainless Steel alloy 316L (SS316L). To evaluate the suitability of the BJ process towards the HTR, high level specifications of the application are translated to materials capability requirements. Subsequently, at-temperature materials testing is conducted on as-printed and sintered additively manufactured coupons. Data from the coupons are compared against cast and wrought SS316L data obtained from the literature. Results show that the tensile properties from the BJ process compare well against cast properties. Furthermore, a baseline analysis of creep testing data is established for the BJ process, and insights are drawn from the results towards future improvements of the process. Full article
(This article belongs to the Section Additive Manufacturing)
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16 pages, 11903 KiB  
Article
Behaviour Aspects of an EB-PVD Alumina (Al2O3) Film with an Interlayer (NiCrAlY) Deposited on AISI 316L Steel Investigated in Liquid Lead
by Daniel Petrescu, Alexandru Nitu, Florentina Golgovici, Ioana Demetrescu and Mircea Corban
Metals 2023, 13(3), 616; https://doi.org/10.3390/met13030616 - 19 Mar 2023
Cited by 1 | Viewed by 1896
Abstract
The use of lead as a primary coolant is one of the most attractive options for next-generation lead-cooled fast reactor systems (LFR). Despite many favourable features, liquid Pb is a harsh environment that induces many problems on metallic components. Therefore, candidate materials for [...] Read more.
The use of lead as a primary coolant is one of the most attractive options for next-generation lead-cooled fast reactor systems (LFR). Despite many favourable features, liquid Pb is a harsh environment that induces many problems on metallic components. Therefore, candidate materials for LFR must be qualified, and the solutions to improve their properties must be found. This paper’s objective is to present the results obtained from the tensile tests of AISI 316L steel in liquid lead at 400 °C, 450 °C, and 500 °C, and the short-term corrosion tests performed on coated and uncoated AISI 316L steel at 550 °C. The coating was made of Al2O3 with a CrNiAlY interlayer using the electron beam-physical vapor deposition (EB-PVD) technique. Both the mechanical and corrosion tests were performed in stagnant lead saturated with oxygen. After testing, the specimens were characterised by several analyses, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), optical microscopy (OM), scratching test, and Vickers micro-hardness test. The tensile test results highlight the ductile behaviour of the material, and in the case of the corrosion tests, the coatings prove to be effective in protecting the substrate from the harsh environment. Full article
(This article belongs to the Section Metallic Functional Materials)
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14 pages, 7041 KiB  
Article
Characteristics for Gallium-Based Liquid Alloys of Low Melting Temperature
by Jianfei Shentu, Jiatong Pan, Hao Chen, Chunlin He, Youbin Wang, Gjergj Dodbiba and Toyohisa Fujita
Metals 2023, 13(3), 615; https://doi.org/10.3390/met13030615 - 19 Mar 2023
Cited by 11 | Viewed by 4400
Abstract
Gallium alloys are ideal base carriers for temperature-sensitive ferrofluids, which can be used for energy convection, soft robotics, microchannels, magnetorheological devices, etc. In this study, gallium was mixed with different substances (In, Sn, Zn, Ge, and Al) to obtain a low melting point, [...] Read more.
Gallium alloys are ideal base carriers for temperature-sensitive ferrofluids, which can be used for energy convection, soft robotics, microchannels, magnetorheological devices, etc. In this study, gallium was mixed with different substances (In, Sn, Zn, Ge, and Al) to obtain a low melting point, reduce the wetness and adhesion of its alloys, and realize low viscosity. The melting point, contact angle on certain solid plates, viscosity, and viscoelasticity of the gallium alloys were measured, and some useful gallium alloys were obtained. The experimental results showed that Ga80In10Sn10 had lower wettability at a larger contact angle of 148.6° on the Teflon plate. Here, (Ga80In10Sn10)97Zn3 with a melting point of 8.2 °C, lower than the melting point of Galinstan, was developed. It had a viscosity about three times that of water at room temperature and an elastic response from 0.1 to 100 Hz at a 1% strain amplitude for the viscoelasticity. It was expected that a kind of temperature-sensitive magnetic fluid with a gallium-based liquid alloy as the base carrier liquid would be prepared in the future with Teflon as the container to achieve energy conversion under the drive of the magnetic field. Full article
(This article belongs to the Special Issue Advances in Characterization of Heterogeneous Metals/Alloys)
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12 pages, 13890 KiB  
Article
Evaluation and Analysis of the Influence of Rare-Earth Ce on Inclusions in Heavy Rail Steel
by Guojun Bai, Jichun Yang and Wenjing Liang
Metals 2023, 13(3), 614; https://doi.org/10.3390/met13030614 - 19 Mar 2023
Cited by 4 | Viewed by 1257
Abstract
The effect of rare-earth Ce on the evolution behaviour of inclusions in heavy rail steel was studied. The addition of Ce can significantly reduce the number and size of class A, B, D, and Ds inclusions in the heavy rail steel smelting process. [...] Read more.
The effect of rare-earth Ce on the evolution behaviour of inclusions in heavy rail steel was studied. The addition of Ce can significantly reduce the number and size of class A, B, D, and Ds inclusions in the heavy rail steel smelting process. According to the statistical analysis of the size of inclusions in steel, the number and size of A and B inclusions in steel tend to decrease significantly, while D and Ds inclusions disappear. Ce splits the aluminium inclusion into several small-sized inclusions and improves the morphology of the large-size aluminium inclusion, thereby making aggregation and growth difficult while facilitating easy floating and removal. Because the addition of Ce reduces the concentration of S element in steel, MnS inclusions are difficult to grow. The decrease in the number and size of core inclusions required for MnS growth leads to a corresponding decrease in the number and size of MnS inclusions. Meanwhile, the S element also easily gathers on the surface of CaO–MgO–Al2O3–SiO2–CeO inclusions, forming composite inclusions that are more easily removed, thus reducing the quantity and size of MnS inclusions. Full article
(This article belongs to the Special Issue Advanced Tundish Metallurgy and Clean Steel Technology)
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12 pages, 9519 KiB  
Article
Study of Morphology and Corrosion Behavior of Aluminum Coatings on Steel Substrates under Simulated Acid Rain Conditions
by Bo Li, Lei Fan, Yi Wen, Jinhang He, Jianfeng Su, Shiyuan Zhou, Shifeng Liu and Zhiqing Zhang
Metals 2023, 13(3), 613; https://doi.org/10.3390/met13030613 - 19 Mar 2023
Cited by 3 | Viewed by 1798
Abstract
In this paper, aluminum coatings were prepared on a steel substrate by thermal spraying, and the corrosion morphology and corrosion resistance of the coating were investigated by salt spray and immersion tests. The results showed that after three months of salt spray tests, [...] Read more.
In this paper, aluminum coatings were prepared on a steel substrate by thermal spraying, and the corrosion morphology and corrosion resistance of the coating were investigated by salt spray and immersion tests. The results showed that after three months of salt spray tests, the coating still exhibited a surface morphology without significant damage and had good damage tolerance. Further effective protection of the substrate can be achieved by spraying the coating surface with paint. After three months of immersion test, the corrosion rate of samples with thicker coatings was located between 0.002 mm/y and 0.005 mm/y, and only a small amount of corrosion products was observed on the coating surface. The coated samples after salt spray and immersion tests maintained sufficient adhesion (17.07 MPa and 19.25 MPa), and the surface aluminum coating was highly reliable for protection of the steel substrate. In general, the reliability of the coating can be further improved by painting the surface of the thicker Al coating. This provides more ideas for the protection of transmission and transformation equipment. Full article
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16 pages, 3925 KiB  
Article
Fabrication of Mn–Co Alloys Electrodeposited on AISI 430 Ferritic Stainless Steel for SOFC Interconnect Applications
by Saravut Thanedburapasup, Nattapol Wetchirarat, Angkana Muengjai, Watcharapon Tengprasert, Panya Wiman, Thammaporn Thublaor, Putinun Uawongsuwan, Thamrongsin Siripongsakul and Somrerk Chandra-ambhorn
Metals 2023, 13(3), 612; https://doi.org/10.3390/met13030612 - 18 Mar 2023
Cited by 4 | Viewed by 1696
Abstract
Mn–Co alloys were electroplated on AISI 430 stainless steel using an electrodeposition technique with the aim to reduce oxidation and chromium volatilization. The electroplating parameters were designed to improve the coating quality. The increased current density with decreased MnSO4 content resulted in [...] Read more.
Mn–Co alloys were electroplated on AISI 430 stainless steel using an electrodeposition technique with the aim to reduce oxidation and chromium volatilization. The electroplating parameters were designed to improve the coating quality. The increased current density with decreased MnSO4 content resulted in a denser coating layer. A sample coated with 0.10 M CoSO4 and 0.50 MnSO4 at 350 mA cm−2 showed the best oxidation resistance after being oxidized at 800 °C for 90 h. The X-ray diffraction (XRD) result revealed that the oxide growth on the surface of the coated samples mainly formed oxides of MnCo2O4, MnCr2O4, and Cr2O3. The chromium volatilization was evaluated by exposing the coated samples to humidified synthetic air at 800 °C for 96 h. The mass flux of Cr volatilization was on the order of 10−11 g cm−2 s−1. Furthermore, different heat treatments in O2 and CO2 atmospheres were compared. Annealing in CO2 at 800 °C for 4 h helped increase the Mn–Co coating density. The relationship between the porosity and its failure behavior was also discussed. Full article
(This article belongs to the Special Issue High Temperature Corrosion or Oxidation of Metals and Alloys)
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20 pages, 15445 KiB  
Article
Investigation on the Microstructure and Mechanical Properties of Ni-Based Superalloy with Scandium
by Lin Ye, Feng Liu, Heng Dong, Xiaoqiong Ouyang, Xiangyou Xiao, Liming Tan and Lan Huang
Metals 2023, 13(3), 611; https://doi.org/10.3390/met13030611 - 18 Mar 2023
Viewed by 1711
Abstract
In this work, a method concerning thermal consolidation is proposed to simulate the traditional powder metallurgy process and accomplish the composition screening of powder metallurgy Ni-based superalloys U720Li and RR1000 with rare metal scandium, and superalloys with zero scandium addition, medium scandium addition [...] Read more.
In this work, a method concerning thermal consolidation is proposed to simulate the traditional powder metallurgy process and accomplish the composition screening of powder metallurgy Ni-based superalloys U720Li and RR1000 with rare metal scandium, and superalloys with zero scandium addition, medium scandium addition and high scandium addition are selected. Then effects of scandium on the microstructure and mechanical properties of superalloys are further investigated through fast hot pressed sintering. The results indicate that scandium doping can effectively refine the grain through modifying the size and volume fraction of primary γ’ precipitates at the grain boundary. Meanwhile, scandium can promote the growth and precipitation of secondary γ’ precipitates to some extent. Due to the comprehensive effects of γ’ precipitate modification and grain boundary strengthening, as-sintered U720Li with 0.043 wt.% scandium presents an excellent combination of tensile strength and ductility at ambient and elevated temperature while as-sintered RR1000 with 0.064 wt.% scandium has a good performance at elevated temperature. Full article
(This article belongs to the Special Issue Advances in Modeling and Simulation in Metal Forming)
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4 pages, 179 KiB  
Editorial
Technological Aspects in Fatigue Design of Metallic Structures
by Martin Leitner
Metals 2023, 13(3), 610; https://doi.org/10.3390/met13030610 - 18 Mar 2023
Viewed by 912
Abstract
Traditional manufacturing processes, such as welding and casting, and modern techniques, such as additive manufacturing, can significantly affect the local material properties of metallic materials [...] Full article
(This article belongs to the Special Issue Technological Aspects in Fatigue Design of Metallic Structures)
64 pages, 8569 KiB  
Review
A Review on Processing–Microstructure–Property Relationships of Al-Si Alloys: Recent Advances in Deformation Behavior
by Soumya Sobhan Dash and Daolun Chen
Metals 2023, 13(3), 609; https://doi.org/10.3390/met13030609 - 17 Mar 2023
Cited by 18 | Viewed by 6351
Abstract
While research on lightweight materials has been carried out for decades, it has become intensified with recent climate action initiatives leading pathways to net zero. Aluminum alloys are at the pinnacle of the light metal world, especially in the automotive and aerospace industries. [...] Read more.
While research on lightweight materials has been carried out for decades, it has become intensified with recent climate action initiatives leading pathways to net zero. Aluminum alloys are at the pinnacle of the light metal world, especially in the automotive and aerospace industries. This review intends to highlight recent developments in the processing, structure, and mechanical properties of structural Al-Si alloys to solve various pressing environmental issues via lightweighting strategies. With the excellent castability of Al-Si alloys, advancements in emerging casting methods and additive manufacturing processes have been summarized in relation to varying chemical compositions. Improvements in thermal stability and electrical conductivity, along with superior mechanical strength and fatigue resistance, are analyzed for advanced Al-Si alloys with the addition of other alloying elements. The role of Si morphology modification, along with particle distribution, size, and precipitation sequencing, is discussed in connection with the improvement of static and dynamic mechanical properties of the alloys. The physics-based damage mechanisms of fatigue failure under high-cycle and low-cycle fatigue loading are further elaborated for Al-Si alloys. The defect, porosity, and surface topography related to manufacturing processes and chemical compositions are also reviewed. Based on the gaps identified here, future research directions are suggested, including the usage of computational modeling of microstructures and the integration of artificial intelligence to produce mass-efficient and cost-effective solutions for the manufacturing of Al-Si alloys. Full article
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14 pages, 14723 KiB  
Article
Development of a New Micro Drilling Tool with H-Shaped Chisel Edge
by Yue Ma, Zhiqiang Liang, Kun Wan, Rongbin Cai, Linfeng Yi, Jianfei Li, Fei Wang, Xu Zhao, Rui Chen and Xibin Wang
Metals 2023, 13(3), 608; https://doi.org/10.3390/met13030608 - 17 Mar 2023
Cited by 2 | Viewed by 1560
Abstract
In order to improve the tool life and micro-hole machining quality, the H-shaped chisel edge micro-drill (HCE-MD) was developed in this paper. The HCE-MD was characterized by the inner edge formed through the chisel edge thinning. In the micro-drilling process, the inner edge [...] Read more.
In order to improve the tool life and micro-hole machining quality, the H-shaped chisel edge micro-drill (HCE-MD) was developed in this paper. The HCE-MD was characterized by the inner edge formed through the chisel edge thinning. In the micro-drilling process, the inner edge can perform positive rake cutting, so the machining area of the workpiece extruded by cutting edge with a negative rake angle is reduced. Based on this, the distribution of rake angle near the chisel edge corner is improved. Then, the HCE-MD was fabricated on the six-axis CNC grinding machine. The grinding process parameters of the micro-drill were optimized based on the orthogonal grinding test and grey relational grade theory. The size and shape accuracy of the micro-drill were controlled by the multi-axis linkage grinding method and the movement-axis micro compensation method. Finally, the 0.25 mm HCE-MD was fabricated with the cutting edge radius of 1.94 μm and the flank surface roughness of 0.25 μm. The drilling performance of HCE-MD was evaluated through comparative drilling experiments. The experimental results show that, compared with common micro drill, the HCE-MD produced lower thrust force and better micro-hole roundness accuracy, and reduced the micro-drill wear on the chisel edge and the flank. Full article
(This article belongs to the Special Issue Advanced Metal Cutting Technology and Tools)
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