Metals

14 pages, 6830 KiB

Open AccessArticle

Layer Approach to Model Fatigue Strength of Surface-Hardened Components

by Dénes Dobberke, Martin Leitner, Jens Wiebesiek and Jürgen Fröschl

Metals 2024, 14(7), 754; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070754 (registering DOI) - 25 Jun 2024

This paper deals with a surface-hardened forged steel that is commonly used for powertrain components like gears, axles or crankshafts. In order to increase static and fatigue strength and to minimise wear, surface treatments like induction hardening lead to a significant microstructural change [...] Read more.

This paper deals with a surface-hardened forged steel that is commonly used for powertrain components like gears, axles or crankshafts. In order to increase static and fatigue strength and to minimise wear, surface treatments like induction hardening lead to a significant microstructural change within heat-affected zones. The aim of this study was to elaborate a method for a reliable computational estimation of the local fatigue strength by considering local material properties. The method is based on experimental test results, where specimens were extracted from forged crankshafts and further heat-treated to investigate the fatigue strength of the unhardened and hardened material condition. The experimental test data were fundamental in defining elaborated Haigh diagrams, enabling a more reliable local fatigue assessment. The comparison of the component safety within the fatigue strength verification for a crankshaft section under alternate bending resulted in

28 %

-more progressive dimensioning of surface hardened layers. Full article

(This article belongs to the Special Issue Fatigue, Fracture and Damage of Steels)

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17 pages, 5601 KiB

Open AccessArticle

The Influence of Insertion Depth of Inorganic Materials on Solidification Microstructure and Segregation of 2.5-ton 42CrMo Ingot

by Shujian Sun, Yonglong Du, Zhenqiang Zhang, Danqing Jiang, Songzhe Xu and Zhongming Ren

Metals 2024, 14(7), 753; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070753 (registering DOI) - 25 Jun 2024

Viewed by 86

Abstract

In this work, a novel internal heat absorption technology using inorganic material rods is employed during the solidification process of steel ingots, aiming to control their solidification and improve the quality of the final product. The study investigates the effect of the insertion [...] Read more.

In this work, a novel internal heat absorption technology using inorganic material rods is employed during the solidification process of steel ingots, aiming to control their solidification and improve the quality of the final product. The study investigates the effect of the insertion depth of inorganic materials on the solidification microstructure and macrosegregation of 2.5-ton 42CrMo ingots. The mechanical properties of samples from the product are also tested. A numerical simulation model for casting 2.5-ton ingots is established and implemented in Ansys Fluent fluid simulation software, with inorganic material rods set at different preset depths. The simulation explores the physical processes of the melting and floating of inorganic materials in molten steel, as well as their effects on the temperature and flow fields of the material. The results show that deeper insertion of inorganic materials (200 mm from the hot top) reduces the tendency for macrosegregation compared to that at the insertion depth of 100 mm. Specifically, the positive segregation area decreases by 10.35%, while the negative segregation area decreases by 15.32%. Moreover, deeper insertion results in a significant refinement of the solidification microstructure, ultimately enhancing the mechanical properties of the products machined from the ingots (i.e., the yield strength increased by 4.7%). The numerical simulation results indicate that as the placement depth of inorganic materials in the ingot mold increases, the cooling effect becomes more significant, the flow area of molten steel initiated by the inorganic materials expands, and the linear velocity of the double-circle flow increases. This further explains why the solidification quality of the ingots improves with the increasing placement depth of inorganic materials. Full article

14 pages, 1638 KiB

Open AccessArticle

Study of Phase Transformations and Interface Evolution in Carbon Steel under Temperatures and Loads Using Molecular Dynamics Simulation

by Chao Wen, Zhengminqing Li, Hongyan Wu and Jianfeng Gu

Metals 2024, 14(7), 752; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070752 (registering DOI) - 25 Jun 2024

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Abstract

Carbon steel materials are widely used in mechanical transmission. Under different temperature and pressure service conditions, the microscopic changes of stress and strain that are difficult to detect and analyze by experimental means will lead to failure deformation, thus affecting their operational stability [...] Read more.

Carbon steel materials are widely used in mechanical transmission. Under different temperature and pressure service conditions, the microscopic changes of stress and strain that are difficult to detect and analyze by experimental means will lead to failure deformation, thus affecting their operational stability and life. In this study, the molecular dynamics method is used to simulate the heating–cooling phase transition process of common carbon steel materials. Austenite transformation temperatures of 980 K (0.2 wt.%) and 1095 K (0.5 wt.%) are acquired which is determined by the volume hysteresis before and after transformation, which is consistent with the results of JMatPro phase diagram analysis. The internal stress state of the material varies between compressive stress and tensile stress due to the change of phase structure, and the dislocation characteristics during the phase transition period are observed to change significantly. Then, an α/γ two-phase interface model is constructed to study the migration of the phase interface and the change of the phase structure by applying a continuously changing external load. At the same time, the transition pressure of α→ϵ is obtained with a value of 37 GPa under three different initial loads showing the independence of the initial load and the historical path. Based on the molecular dynamics simulation and the phase diagram calculation of the carbon steel, the analysis method for the microstructure transformation and the stress–strain behavior of the phase interface under the external load can provide a reference for the design of microstructure and mechanical properties of alloy steel in the future. Full article

11 pages, 2172 KiB

Open AccessArticle

Effect of Electric Pulse Treatment on Microstructure and Mechanical Property of Laser Powder Bed Fused IN718

by Hongmei Zhang, Jie Liu and Zhanfeng Wang

Metals 2024, 14(7), 751; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070751 (registering DOI) - 25 Jun 2024

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Abstract

This study investigated the impact of electric pulse treatment (EPT) on the microstructure and mechanical properties of laser powder bed fused Inconel 718 (IN718). Through a comprehensive experimental characterization, we found that EPT induced significant improvements in the microstructure of IN718. In the [...] Read more.

This study investigated the impact of electric pulse treatment (EPT) on the microstructure and mechanical properties of laser powder bed fused Inconel 718 (IN718). Through a comprehensive experimental characterization, we found that EPT induced significant improvements in the microstructure of IN718. In the YOZ plane of EPT-700, the molten pool diminished and replaced by a grain boundary with granular Ni₃Nb precipitates, and the dislocations increased while the irregular porosity decreased. Concurrently, enhanced mechanical properties of EPT-700 were obtained, including a hardness of 354.7 HV, an ultimate tensile strength of 930.21 MPa, and an elongation of 34.35%. Fractographic analysis revealed a transition in fracture mechanisms, highlighting the intricate relationship between microstructural modifications induced by EPT and mechanical response under load. These findings underscore the potential of EPT as a promising post-processing technique for optimizing the microstructure and mechanical properties of IN718 components fabricated via laser powder bed fusion additive manufacturing. This study contributes to the advancement of knowledge in the field of additive manufacturing and provides valuable insights for the development of high-performance metallic components. Full article

(This article belongs to the Section Additive Manufacturing)

12 pages, 777 KiB

Open AccessArticle

On the Efficiency of Air-Cooled Metal Foam Heat Exchangers

by Thomas Fiedler, Nima Movahedi and Rohan Stanger

Metals 2024, 14(7), 750; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070750 (registering DOI) - 25 Jun 2024

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Abstract

This study analyses the heat transfer performance of metal foam heat exchangers through experimental measurements. Using counter-gravity infiltration casting, open-cell aluminium foam elements were manufactured to embed a copper tube for internal mass flow containment. Heat transfer experiments were conducted under natural and [...] Read more.

This study analyses the heat transfer performance of metal foam heat exchangers through experimental measurements. Using counter-gravity infiltration casting, open-cell aluminium foam elements were manufactured to embed a copper tube for internal mass flow containment. Heat transfer experiments were conducted under natural and forced convection conditions, with the airflow controlled in a wind tunnel. A stream of warm water within the internal foam component served as the heat source, transferring thermal energy to the surrounding air flowing through the external foam component of the heat exchanger. The results showed a significantly enhanced heat transfer performance with aluminium foam compared to a single copper tube. Thermal resistance models were developed to elucidate the heat transfer mechanisms, highlighting the effectiveness of air-cooled metal foam heat exchangers. These findings underscore the potential of metal foam heat exchangers as cost-effective alternatives for various thermal management applications. Full article

(This article belongs to the Topic Modern Material Technologies Intended for Industrial Applications)

17 pages, 7038 KiB

Open AccessArticle

Temperature-Dependent Mechanical Behaviors and Deformation Mechanisms in a Si-Added Medium-Entropy Superalloy with L1₂ Precipitation

by Tuanwei Zhang, Tianxiang Bai, Renlong Xiong, Shunhui Luo, Hui Chang, Shiyu Du, Jinyao Ma, Zhiming Jiao, Shengguo Ma, Jianjun Wang and Zhihua Wang

Metals 2024, 14(7), 749; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070749 (registering DOI) - 25 Jun 2024

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Abstract

A novel Ni-Co-Cr-based medium-entropy superalloy with a high Si content (7.5 at%) strengthened by an L1₂ phase was developed. The pure L1₂ phase, characterized by an average size of 50 nm and a volume fraction of 46%, was precipitated within the [...] Read more.

A novel Ni-Co-Cr-based medium-entropy superalloy with a high Si content (7.5 at%) strengthened by an L1₂ phase was developed. The pure L1₂ phase, characterized by an average size of 50 nm and a volume fraction of 46%, was precipitated within the FCC matrix. This alloy exhibits excellent mechanical properties over a wide range of temperatures from 77 K to 1073 K. A yield strength of 1005 MPa, an ultimate tensile strength of 1620 MPa, and a tensile elongation of 36% were achieved at 77 K, with a maximum value of 4.8 GPa at the second stage of the work-hardening rate. The alloy maintains a basically consistent yield strength of approximately 800 MPa from 298 K to 973 K, showcasing significant strain-hardening capabilities, with values of 2.5 GPa, 3.7 GPa, and 4.8 GPa at 873 K, 298 K, and 77 K, respectively. Microscopic analysis revealed that at room and cryogenic temperatures, multilayer stacking faults (SFs), SF bands, and SF networks, rather than twins, effectively stored a large number of dislocations and impeded dislocation movement, thereby enhancing the work-hardening ability of the alloy. Furthermore, at 773 K, the primary deformation mechanism involved high-density dislocation walls (HDDWs) consisting of dislocation tangles and SF lines. As the temperature rose to 973 K, the work-hardening process was influenced by the APB shearing mechanism (in the form of dislocation pairs), SF lines, and microtwins generated through atomic rearrangement. This study not only provides valuable insights for the development of new oxidation-resistant superalloys but also enhances our understanding of high-temperature deformation mechanisms. Full article

14 pages, 6043 KiB

Open AccessArticle

Phase Transformations after Heat Treating an As-Cast Fe-30Mn-8.8Al-0.3Si-0.15C Steel

by Victor M. Lopez-Hirata, Eduardo Perez-Badillo, Maribel Leticia Saucedo-Muñoz, Felipe Hernandez-Santiago and Jose David Villegas-Cardenas

Metals 2024, 14(7), 748; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070748 (registering DOI) - 25 Jun 2024

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Abstract

The phase transformations in an as-cast Fe-30Mn-8.8Al-0.3Si-0.15C steel were analyzed experimentally and numerically with a Calphad-based method during heat treatment. The nonequilibrium phases were determined using the Thermo-Calc Scheil module and the equilibrium phases with Themo-Calc based on the steel chemical composition. The [...] Read more.

The phase transformations in an as-cast Fe-30Mn-8.8Al-0.3Si-0.15C steel were analyzed experimentally and numerically with a Calphad-based method during heat treatment. The nonequilibrium phases were determined using the Thermo-Calc Scheil module and the equilibrium phases with Themo-Calc based on the steel chemical composition. The precipitated phases were analyzed with TC-PRISMA using the chemical composition, nucleation site, and temperature among other factors. An ingot of this chemical composition was vacuum-melted using pure elements under an Ar gas atmosphere. As-cast steel specimens were annealed and solution-treated, quenched, and then aged at different temperatures. Heat-treated specimens were analyzed by different techniques. The results indicated that the microconstituents are the α and γ phases for the as-cast, homogenized, and quenched conditions. The main difference among these conditions is the distribution and size of the γ phase, which produced a change in hardness from 209 to 259 VHN. In contrast, the aging treatment at 750 °C caused a decrease in hardness from 492 to 306 VHN, which is attributable to the increase in volume fraction of the γ phase. On the other hand, the aging treatment at 550 °C promoted precipitation hardening from 259 to 649 VHN because of the κ precipitate formation. The calculated results for the different heat treatments with the Calphad-based method agreed well with the experimental ones. In addition, the intragranular precipitation of the κ phase could be simulated using the nucleation and growth and coarsening mechanisms based on a Calphad method. Full article

(This article belongs to the Special Issue Heat Treatment, Microstructures, and Mechanical Properties of Metallic Materials)

21 pages, 7490 KiB

Open AccessArticle

Influence of the Material Production Route on the Material Properties and the Machinability of the Lead-Free Copper-Zinc-Alloy CuZn40 (CW509L)

by Kilian Brans, Stefan Kind, Markus Meurer and Thomas Bergs

Metals 2024, 14(7), 747; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070747 (registering DOI) - 25 Jun 2024

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Abstract

To improve the machinability properties of CuZn-alloys, these are alloyed with the element lead. Due to its toxicity, a variety of legislative initiatives aim to reduce the lead content in CuZn-alloys, which results in critical machinability problems and a reduction in the productivity [...] Read more.

To improve the machinability properties of CuZn-alloys, these are alloyed with the element lead. Due to its toxicity, a variety of legislative initiatives aim to reduce the lead content in CuZn-alloys, which results in critical machinability problems and a reduction in the productivity of machining processes. Basically, there are two ways to solve the critical machinability problems when machining lead-free CuZn-alloys: optimizing the machinability of lead-free materials on the material side or adapting the processes and the respective process parameters. In this study, the focus is on material-side machinability optimization by investigating the influence of a targeted variation in the process chain in the material production route. To evaluate the influence of the material production route, the brass alloy CuZn40 (CW509L) was produced in four variants by varying the degree of work hardening and the use of heat treatments, and all four variants were evaluated in terms of their machinability. To evaluate the machinability, the cutting force components, the chip temperature, the chip formation, and the chip shape were analyzed. Clear influences of the material production route were identified, particularly with regard to the chip formation mechanisms and the resulting chip shape. Full article

(This article belongs to the Special Issue Advances in Copper, Copper Alloys and Their Processing)

29 pages, 17115 KiB

Open AccessArticle

Optimizing Rolling Strategies for API 5L X80 Steel Heavy Plates Produced by Thermomechanical Processing in a Reversible Single-Stand Mill

by Luiz Gustavo de Oliveira Abreu, Geraldo Lúcio de Faria, Ricardo José de Faria, Daniel Bojikian Matsubara and Rodrigo Rangel Porcaro

Metals 2024, 14(7), 746; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070746 (registering DOI) - 25 Jun 2024

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Abstract

This study focuses on advancing the production of predominantly bainitic heavy plates to meet the API 5L X80 standard. The investigation involves a thorough evaluation of the influence of rolling parameters and austenite conditioning on both microstructural characteristics and mechanical properties. Accurate specifications [...] Read more.

This study focuses on advancing the production of predominantly bainitic heavy plates to meet the API 5L X80 standard. The investigation involves a thorough evaluation of the influence of rolling parameters and austenite conditioning on both microstructural characteristics and mechanical properties. Accurate specifications for chemical composition, processing temperatures, and mean deformations were established using mathematical models and bibliographical references. Four rolling conditions were performed in a reversible single-stand mill, allowing for comprehensive comparison and critical analysis. Microstructural and mechanical characterizations were performed utilizing several techniques, including optical microscopy (OM), scanning electron microscopy (SEM), tensile tests, Charpy impact tests, and hardness tests to ensure adherence to API 5L standards. Additionally, the SEM-EBSD (electron backscattered diffraction) technique was employed for a complementary analysis. The EBSD analysis included crystallographic misorientation maps, mean kernel misorientation parameters (𝜗), low- and high-angle grains boundaries, mean equivalent diameter, and evaluation of the contribution of different strengthening mechanisms to yield strength. Results underscored the significant influence of austenite conditioning on both microstructure and mechanical properties. Considering the specificities of a reversible single-stand mill, it was concluded that, unlike the classic approach for ferritic or ferritic–pearlitic HSLA (high-strength low-alloy steel), when a product with a predominantly bainitic microstructure is required, the accumulated deformation in the austenite during the finishing rolling stage, as well as its temperature, must be meticulously controlled. It was shown that the greater the deformation and the lower the temperature, the more favorable the scenario for the undesired polygonal ferrite formation, which will deteriorate the material’s performance. Furthermore, an optimized production route was identified and adapted to the specificities of the employed rolling mill. The presented data have great importance for researchers, manufacturers, and users of API 5L X80 heavy plates. Full article

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

26 pages, 2914 KiB

Open AccessArticle

Modeling of Zirconium Atom Redistribution and Phase Transformation Coupling Behaviors in U-10Zr-Based Helical Cruciform Fuel Rods under Irradiation

by Xingdi Chen, Zhexiao Xie, Xiaoxiao Mao and Shurong Ding

Metals 2024, 14(7), 745; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070745 - 24 Jun 2024

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Abstract

Uranium–zirconium metal-based Helical Cruciform Fuels (HCFs) have shown a promising prospect for their use in advanced nuclear reactors. However, during irradiation, dual-phase coexistence and the spatial heterogeneous distribution of zirconium atoms occur at higher powers, affecting the thermo-mechanical coupling behaviors and safety of [...] Read more.

Uranium–zirconium metal-based Helical Cruciform Fuels (HCFs) have shown a promising prospect for their use in advanced nuclear reactors. However, during irradiation, dual-phase coexistence and the spatial heterogeneous distribution of zirconium atoms occur at higher powers, affecting the thermo-mechanical coupling behaviors and safety of fuel elements and assemblies. In this study, based on the phase-field approach, the coupled multi-field governing equations to describe the zirconium diffusion and phase evolution for U-Zr metallic fuels are improved. Furthermore, the corresponding numerical algorithms and procedures for multi-field coupling calculations are developed. The numerical predictions of zirconium atom fraction are in good agreement with the relevant experimental results, validating the developed models, algorithms and programs. The zirconium atom redistribution and phase transformation coupling behaviors in high-power U-10wt%Zr-based HCF rods are also obtained. Moreover, the complex evolution mechanisms of multi-field variables are analyzed. The results indicate the following: (1) the irradiation enhancement of the thermal mobility and chemical mobility plays a critical role in the redistribution of Zr atoms; (2) the multi-field results of HCF rods have helical symmetric characteristics; (3) the contribution competitions of the temperature gradient and chemical potential gradient within the α phase and γ phase significantly influence the zirconium-atom redistribution, with the zirconium-rich zones formed in the elbow region and the zirconium-poor zones appearing inside. These research efforts supply a foundation for the further involvement of mechanical fields in multi-field coupling computation. Full article

(This article belongs to the Special Issue Advances in Metallic Nuclear Reactor Materials)

24 pages, 3790 KiB

Open AccessArticle

Radiation Techniques for Tracking the Progress of the Hydrometallurgical Leaching Process: A Case Study of Mn and Zn

by Nelson Rotich Kiprono, Anna Kawalec, Bartlomiej Klis, Tomasz Smolinski, Marcin Rogowski, Paweł Kalbarczyk, Zbigniew Samczynski, Maciej Norenberg, Beata Ostachowicz, Monika Adamowska, Wojciech Hyk and Andrzej G. Chmielewski

Metals 2024, 14(7), 744; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070744 - 24 Jun 2024

Viewed by 256

Abstract

With advancements in hardware and software, non-destructive radiometric analytical methods have become popular in a wide range of applications. A typical case is the study of the leaching process of metals from mineral ores and mine tailings. The objective of the current study [...] Read more.

With advancements in hardware and software, non-destructive radiometric analytical methods have become popular in a wide range of applications. A typical case is the study of the leaching process of metals from mineral ores and mine tailings. The objective of the current study was to develop a radiometric method based on neutron activation analysis (NAA), in particular, delayed gamma neutron activation analysis (DGNAA), to monitor the process of Mn and Zn leaching from Ti ore, Cu mine tailings, and Zn-Pb mine tailings. The DGNAA method was performed using a neutron source: a deuterium-tritium (D-T) neutron generator for Mn and a MARIA research nuclear reactor for Zn. Laboratory-scale Mn leaching from Ti ores, Cu tailings, and Zn-Pb tailings was investigated using delayed gamma-rays of ⁵⁶Mn (half-life of 2.6 h). The dissolution efficiencies of Mn were found to increase with interaction time and HCl concentration (1 to 5 M) and to vary with the leaching temperature (22.5 to 110 °C). Such results were found to agree with those obtained by total reflection X-ray fluorescence (TXRF) spectrometry for the same samples. ⁶⁵Zn (half-life of 244 days) was chosen to investigate real-time/online leaching of Zn in Ti ore, Cu tailings, and Zn-Pb tailings. During online monitoring, Zn recovery was also reported to increase with increased leaching time. After approximately 300 min of leaching, 80%, 79%, and 53% recovery of Zn in Zn-Pb tailings, Ti ore, and Cu tailings, respectively, were reported. Theoretically, developed mathematical prediction models for ⁶⁵Zn radiotracer analysis showed that the spherical diffusion model requires much less time to attain saturation compared to the linear diffusion model. The results of NAA for Zn were compared with those obtained by handheld X-ray fluorescence (handheld-XRF) and TXRF analysis. The analyzed samples encompassed leached Ti ore, Cu tailings, and Zn-Pb tailings which were subjected to different conditions of leaching time, temperature, and HCl concentrations. The XRF analysis confirmed that the leaching efficiencies of Zn rise with the increase in leaching time and HCl concentration and fluctuate with leaching temperature. The developed approach is important and can be applied in laboratories and industrial setups for online monitoring of the recovery of any element whose isotopes can be activated using neutrons. The efficiency of the metal-recovery process has a direct impact on the normal operation and economic advantages of hydrometallurgy. Full article

(This article belongs to the Special Issue Recovery and Recycling of Metals from the Wastes of New Energy Industry)

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17 pages, 11602 KiB

Open AccessArticle

Plastic Shakedown Behavior and Deformation Mechanisms of Ti17 Alloy under Long Term Creep–Fatigue Loading

by Jianguo Wang, Tongchi Man, Dong Liu, Zhihong Zhang, Chi Zhang and Yuxiang Sun

Metals 2024, 14(7), 743; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070743 - 22 Jun 2024

Viewed by 275

Abstract

Ti17 alloy is mainly used to manufacture aero-engine discs due to its excellent properties such as high strength, toughness and hardenability. It is often subjected to creep–fatigue cyclic loading in service environments. Shakedown theory describes the state in which the accumulated plastic strain [...] Read more.

Ti17 alloy is mainly used to manufacture aero-engine discs due to its excellent properties such as high strength, toughness and hardenability. It is often subjected to creep–fatigue cyclic loading in service environments. Shakedown theory describes the state in which the accumulated plastic strain of the material stabilizes after several cycles of cyclic loading, without affecting its initial function and leading to failure. This theory includes three behaviors: elastic shakedown, plastic shakedown and ratcheting. In this paper, the creep–fatigue tests (CF) were conducted on Ti17 alloy at 300 °C to study its shakedown behavior under creep–fatigue cyclic loading. Based on the plasticity–creep superposition model, a theory model that accurately describes the shakedown behavior of Ti17 alloy was constructed, and ABAQUS finite element software was used to validate the accuracy of the model. TEM analysis was performed to observe the micro-mechanisms of shakedown in Ti17 alloy. The results reveal that the Ti17 alloy specimens exhibit plastic shakedown behavior after three cycles of creep–fatigue loading. The established finite element model can effectively predict the plastic shakedown process of Ti17 alloy, with a relative error between the experimental and simulation results within 4%. TEM results reveal that anelastic recovery controlled by dislocation bending and back stress hardening caused by inhomogeneous deformation are the main mechanisms for the plastic shakedown behavior of Ti17 alloy. Full article

(This article belongs to the Special Issue Plasticity and Metal Forming)

18 pages, 4660 KiB

Open AccessArticle

Mathematical Modeling of Transient Submerged Entry Nozzle Clogging and Its Effect on Flow Field, Bubble Distribution and Interface Fluctuation in Slab Continuous Casting Mold

by Yuntong Li, Wenyuan He, Changliang Zhao, Jianqiu Liu, Zeyu Yang, Yuhang Zhao and Jian Yang

Metals 2024, 14(7), 742; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070742 - 22 Jun 2024

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Abstract

Submerged entry nozzle (SEN) clogging will affect the production efficiency and product quality in the continuous casting process. In this work, the transient SEN clogging model is developed by coupling the porous media model defined by the user-defined function (UDF) and the discrete [...] Read more.

Submerged entry nozzle (SEN) clogging will affect the production efficiency and product quality in the continuous casting process. In this work, the transient SEN clogging model is developed by coupling the porous media model defined by the user-defined function (UDF) and the discrete phase model (DPM). The effects of the transient SEN clogging process on the flow field, the distribution of argon gas bubbles and the fluctuation of the interface between steel and slag in the concave bottom SEN in the continuous casting slab mold with a cross-section of 1500 mm × 230 mm are studied by coupling transient SEN clogging model, DPM and volume of fluid (VOF) model. The results show that the actual morphology and thicknesses of SEN clogging are in good agreement with the numerical simulation results. The measurement result of the surface velocity is consistent with the numerical simulation result. With increasing the simulation time, the degree of SEN clogging increases. The flow velocities of molten steel flowing from the outlet of the side hole increase, because the flow space is occupied with the clogging inclusions, which leads to the increased number of argon gas bubbles near the narrow wall. The steel–slag interface fluctuation near the narrow walls also increases, resulting in the increased risk of slag entrapment. Full article

28 pages, 2966 KiB

Open AccessArticle

Experimental Investigation of Stress Concentration and Fatigue Behavior in 9% Ni Steel Welded Joints under Cryogenic Conditions

by Yu-Yao Lin, Sang-Woong Han, Young-Hwan Park and Do Kyun Kim

Metals 2024, 14(7), 741; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070741 - 22 Jun 2024

Viewed by 214

Abstract

This experimental study delves into the intricate mechanics of stress concentration and fatigue behavior exhibited by 9% Ni steel welded joints under cryogenic conditions. The study specifically examines butt-welded, fillet longitudinal, and fillet transverse specimens, comparing their fatigue properties under room and cryogenic [...] Read more.

This experimental study delves into the intricate mechanics of stress concentration and fatigue behavior exhibited by 9% Ni steel welded joints under cryogenic conditions. The study specifically examines butt-welded, fillet longitudinal, and fillet transverse specimens, comparing their fatigue properties under room and cryogenic temperatures. Notably, determining hot-spot stress presents a challenge, as it cannot be directly obtained through traditional means. To overcome this limitation, a method for predicting hot-spot stress is introduced, which considers the effects of misalignments and weld bead characteristics. The study also highlights the impact of grip-clamping-induced specimen deformation and the reduced middle section on stress concentration resulting from misalignments. Furthermore, it proposes separate consideration of the effects of the weld bead on the axial nominal stress and on the bending stress of the specimen. The accuracy of strain gauge measurements in cryogenic environments is addressed by suggesting a method to correct the output of 2-wire strain gauges using a fixed ratio derived from 2-wire and 3-wire strain gauges. By comparing predicted hot-spot stress with actual measurements, the study validates the reliability of the proposed predictive method. These findings contribute to a deeper understanding of the behavior of 9% Ni steel welded joints under cryogenic conditions and provide valuable insights for design and engineering in similar applications. Full article

(This article belongs to the Special Issue Research on Mechanical Properties, Deformation, and Microstructures of Metallic Materials)

18 pages, 12501 KiB

Open AccessArticle

Effect of Ag and Cu Content on the Properties of Zn-Ag-Cu-0.05Mg Alloys

by Gloria Jara-Chávez, Adrián Amaro-Villeda, Bernardo Campillo-Illanes, Marco Ramírez-Argáez and Carlos González-Rivera

Metals 2024, 14(7), 740; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070740 - 21 Jun 2024

Viewed by 253

Abstract

Zn-Ag-Cu alloys have recently attracted attention as alloy candidates for biomedical applications, but, to date, they have not achieved the required mechanical properties. To improve the mechanical properties of Zn-Ag-Cu-base alloys, in this work, the effects of the presence of increasing amounts of [...] Read more.

Zn-Ag-Cu alloys have recently attracted attention as alloy candidates for biomedical applications, but, to date, they have not achieved the required mechanical properties. To improve the mechanical properties of Zn-Ag-Cu-base alloys, in this work, the effects of the presence of increasing amounts of Ag and Cu as alloying elements on the properties of four 0.05% Mg-micro-alloyed Zn-Ag-Cu base alloys are explored. The alloys were manufactured in an electric furnace with a protective atmosphere using increasing amounts of Ag and Cu as alloying agents, and were cast in a metallic mold. The samples obtained were thermomechanically processed by hot extrusion. Three of the four alloys under study presented increasing amounts of the second phase (Ag, Cu)Zn₄, high mechanical properties, a microstructure and mechanical behavior characteristic of heteromaterials with a heterogeneous lamella-structure, and met the requirements of the mechanical properties, corrosion rate, antibacterial properties against S. aureus, and the cytotoxicity required for biomedical applications. It seems possible to tune the properties of the ZnAgCu-0.05% Mg alloys by changing the Ag and Cu contents. Full article

(This article belongs to the Special Issue Advances in Metal-Based Biomedical Materials: Composition Design and Surface Modification)

15 pages, 54480 KiB

Open AccessArticle

Vision-Assisted Probabilistic Inference of Milling Stability through Fully Bayesian Gaussian Process

by Vahid Ostad Ali Akbari, Andrea Eichenberger and Konrad Wegener

Metals 2024, 14(7), 739; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070739 - 21 Jun 2024

Viewed by 281

Abstract

This paper presents a physics-free Bayesian approach for the learning and inference of probabilistic stability charts in milling operations. The approach does not require any information from machine tool structural dynamics or cutting force coefficients, and the underlying learning algorithm can operate with [...] Read more.

This paper presents a physics-free Bayesian approach for the learning and inference of probabilistic stability charts in milling operations. The approach does not require any information from machine tool structural dynamics or cutting force coefficients, and the underlying learning algorithm can operate with limited training data. A Fully Bayesian Gaussian Process with distributions on its kernel hyperparameters is employed to enable information transfer between different machine and process configurations. The vision system further automates the detection of necessary dimensions from the tool–holder assembly in the machine’s tool magazine, further enhancing the applicability of the approach. Experiments demonstrated the effectiveness of this approach, offering great promise as an industry-friendly solution. Full article

(This article belongs to the Special Issue Laser Ablation and Precision Cutting of Sheet Metal)

18 pages, 4288 KiB

Open AccessArticle

Thermomechanical Behavior of CuAlMn SMA Cellular Structures Obtained by Rapid Investment Casting

by Railson M. N. Alves, Paulo C. S. Silva, Danielle G. L. Cavalcante, Danniel F. Oliveira, Carlos J. De Araújo, João M. P. Q. Delgado and Antonio G. B. Lima

Metals 2024, 14(7), 738; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070738 - 21 Jun 2024

Viewed by 303

Abstract

Shape memory alloy (SMA) bidimensional cellular structures (CSs) have a great potential application in attenuation of vibrations due to reversible martensitic phase transformations induced by thermal or mechanical loading. This work aims to produce a thermal and mechanical characterization of CuAlMn SMA CSs [...] Read more.

Shape memory alloy (SMA) bidimensional cellular structures (CSs) have a great potential application in attenuation of vibrations due to reversible martensitic phase transformations induced by thermal or mechanical loading. This work aims to produce a thermal and mechanical characterization of CuAlMn SMA CSs produced by rapid investment casting (RIC). Structures with different unit cell geometries and thicknesses of 0.5 mm and 1 mm were manufactured by centrifugal RIC. Compression tests at different temperatures were performed on the CS to verify its thermomechanical behavior. We observed that a CS with a thickness of 0.5 mm presents greater mechanical strength and lower levels of maximum force at the end of each 5% compression cycle, ranging from approximately 1/10 to 1/3, compared to structures with a thickness of 1 mm. Among all the CS configurations, the re-entrant structure exhibited higher levels of force, with higher secant stiffness and dissipated energy. The structures resisted the application of compressive forces that varied between 125 N and 500 N for the 0.5 mm CS and between 500 N and 5500 N for the 1 mm CS. Therefore, the results showed that all CuAlMn SMA CSs produced by RIC exhibited sufficient strength to attain strain levels of up to 5% at different temperatures, and that the unit cell geometry can be used to tune the mechanical properties. Full article

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38 pages, 1898 KiB

Open AccessFeature PaperReview

Numerical Simulation as a Tool for the Study, Development, and Optimization of Rolling Processes: A Review

by Adrián Ojeda-López, Marta Botana-Galvín, Leandro González-Rovira and Francisco Javier Botana

Metals 2024, 14(7), 737; https://0-doi-org.brum.beds.ac.uk/10.3390/met14070737 - 21 Jun 2024

Viewed by 191

Abstract

Rolling is one of the most important processes in the metallurgical industry due to its versatility. Despite its inherent advantages, design and manufacturing by rolling still rely on trial-and-error-based optimizations, which reduces its efficiency. To minimize the cost and time spent on the [...] Read more.

Rolling is one of the most important processes in the metallurgical industry due to its versatility. Despite its inherent advantages, design and manufacturing by rolling still rely on trial-and-error-based optimizations, which reduces its efficiency. To minimize the cost and time spent on the development of new rolling schedules, various analytical and numerical methods have been used in recent years. Among other alternatives, simulations based on the finite element method (FEM) are the most widely used. This allows for the analysis of the feasibility of new rolling schedules considering metal alloys with different characteristics, process conditions, or the creation of new operations, as well as the optimization of existing ones. This paper presents a literature review including the latest developments in the field of numerical simulation of rolling processes, which have been classified according to the type of rolling into the following categories: flat rolling, shape rolling, ring rolling, cross-wedge rolling, skew rolling, and tube piercing. Full article

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

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Metals, Volume 14, Issue 7 (July 2024) – 18 articles

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