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Volume 15
Issue 5
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Metals, Volume 15, Issue 5 (May 2025) – 102 articles

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26 pages, 5303 KiB  
Article
Machine Learning-Based Prediction of Fatigue Fracture Locations in 7075-T651 Aluminum Alloy Friction Stir Welded Joints
by Guangming Mi, Guoqin Sun, Shuai Yang, Xiaodong Liu, Shujun Chen and Wei Kang
Metals 2025, 15(5), 569; https://doi.org/10.3390/met15050569 - 21 May 2025
Abstract
Friction stir welding (FSW) is a solid-state joining technique widely used for aluminum alloys in aerospace, automotive, and shipbuilding applications, yet the prediction of fatigue fracture locations within FSW joints remains challenging for structural-life assessment. In this study, we investigate fatigue fracture location [...] Read more.
Friction stir welding (FSW) is a solid-state joining technique widely used for aluminum alloys in aerospace, automotive, and shipbuilding applications, yet the prediction of fatigue fracture locations within FSW joints remains challenging for structural-life assessment. In this study, we investigate fatigue fracture location prediction in 7075-T651 aluminum alloy FSW joints by applying four machine learning methods—decision tree, logistic regression, a three-layer back-propagation artificial neural network (BP ANN), and a novel Quadratic Classification Neural Network (QCNN)—using maximum stress, stress amplitude, and stress ratio as input features. Evaluated on an experimental test set of eight loading conditions, the QCNN achieved the highest accuracy of 87.5%, outperforming BP ANN (75%), logistic regression (50%), and decision tree (37.5%). Building on QCNN outputs and incorporating relevant material property parameters, we derive a Regional Fracture Prediction Formula (RFPF) based on a Fourier-series quadratic expansion, enabling the rapid estimation of fracture zones under varying loads. These results demonstrate the QCNN’s superior predictive capability and the practical utility of the RFPF framework for the fatigue failure analysis and service-life assessment of FSW structures. Full article
(This article belongs to the Special Issue Fatigue Assessment of Metals)
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14 pages, 1940 KiB  
Article
Nanoporous CuAuPtPd Quasi-High-Entropy Alloy Prism Arrays for Sustainable Electrochemical Nitrogen Reduction
by Shuping Hou, Ziying Meng, Weimin Zhao and Zhifeng Wang
Metals 2025, 15(5), 568; https://doi.org/10.3390/met15050568 - 21 May 2025
Abstract
Electrochemical nitrogen reduction reaction (NRR) has emerged as a promising approach for sustainable ammonia synthesis under ambient conditions, offering a low-energy alternative to the traditional Haber–Bosch process. However, the development of efficient and sustainable electrocatalysts for NRR remains a significant challenge. Noble metals, [...] Read more.
Electrochemical nitrogen reduction reaction (NRR) has emerged as a promising approach for sustainable ammonia synthesis under ambient conditions, offering a low-energy alternative to the traditional Haber–Bosch process. However, the development of efficient and sustainable electrocatalysts for NRR remains a significant challenge. Noble metals, known for their exceptional chemical stability under electrocatalytic conditions, have garnered considerable attention in this field. In this study, we report the successful synthesis of nanoporous CuAuPtPd quasi-high-entropy alloy (quasi-HEA) prism arrays through “melt quenching” and “dealloying” techniques. The as-obtained alloy demonstrates remarkable performance as an NRR electrocatalyst, achieving an impressive ammonia synthesis rate of 17.5 μg h−1 mg−1 at a potential of −0.2 V vs. RHE, surpassing many previously reported NRR catalysts. This work not only highlights the potential of quasi-HEAs as advanced NRR electrocatalysts but also provides valuable insights into the design of nanoporous multicomponent materials for sustainable energy and catalytic applications. Full article
(This article belongs to the Special Issue Advances in High-Entropy Alloys’ Microstructure, Properties and Preparation)
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19 pages, 3343 KiB  
Article
Crystal Plasticity Finite Element Simulation of Tensile Fracture of 316L Stainless Steel Produced by Selective Laser Melting
by Guowei Zeng, Ziyang Huang, Bei Deng and Rui Ge
Metals 2025, 15(5), 567; https://doi.org/10.3390/met15050567 - 21 May 2025
Abstract
Selective Laser Melting (SLM) of 316L stainless steel exhibits great potential prospects for engineering applications due to its high strength, high forming freedom, and low material waste. However, due to the unique processing technology of additive manufacturing, challenges related to the microstructure and [...] Read more.
Selective Laser Melting (SLM) of 316L stainless steel exhibits great potential prospects for engineering applications due to its high strength, high forming freedom, and low material waste. However, due to the unique processing technology of additive manufacturing, challenges related to the microstructure and differences in the mechanical properties of the formed parts are inevitable. To investigate the influence of building direction and grain boundary strength on the fracture parameters of SLM 316L stainless steel, electron backscatter diffraction (EBSD) experiments were conducted to characterize the microstructure of SLM 316L stainless-steel specimens. A representative volume element (RVE) model reflecting the microstructure of SLM 316L stainless steel was established based on a combination of the crystal plastic finite element method (CPFEM) and UMAT subroutine technology. The crystal plasticity parameters were determined by comparing the results of tensile tests. Cohesive elements were employed and inserted at the grain boundaries of the polycrystalline RVE to simulate the intergranular fracture behavior of SLM 316L stainless steel under uniaxial tensile loading. The damage and fracture mechanisms of the material at the microscale were analyzed. The simulated tensile stress–strain curves were in good agreement with the experimental results; hence, the combined CPFEM model is suitable for characterizing the mechanical response and fracture behavior of the SLM 316L stainless steel. The results revealed that cracks initiate at stress concentration sites and propagate along grain boundaries with increasing external load, ultimately leading to rupture. Additionally, the building direction influences the location of microcracks and their propagation significantly. Full article
(This article belongs to the Special Issue Multi-scale Simulation of Metallic Materials (2nd Edition))
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21 pages, 14426 KiB  
Article
Corrosion Resistance and Surface Conductivity of 446 Stainless Steel with Electrochemical Cr-Enrichment and Nitridation for Proton Exchange Membrane Fuel Cell (PEMFC) Bipolar Plates
by Ronghai Xu, Yangyue Zhu, Ruigang Zhu and Moucheng Li
Metals 2025, 15(5), 566; https://doi.org/10.3390/met15050566 - 21 May 2025
Abstract
The development of bipolar plate materials with enhanced corrosion resistance and surface conductivity is critical for the commercial application of proton exchange membrane fuel cells (PEMFCs). The corrosion behavior and surface conductivity of electrochemically nitrided 446 stainless steel with and without the pretreatment [...] Read more.
The development of bipolar plate materials with enhanced corrosion resistance and surface conductivity is critical for the commercial application of proton exchange membrane fuel cells (PEMFCs). The corrosion behavior and surface conductivity of electrochemically nitrided 446 stainless steel with and without the pretreatment of Cr-enrichment were investigated in the simulated PEMFC anode and cathode environments (i.e., 0.5 mol L−1 H2SO4 + 2 ppm HF solution bubbled with hydrogen or air at 80 °C) using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma–mass spectrometry (ICP-MS), and electrochemical measurement techniques. Extending the nitriding time from 5 to 30 min enhances the surface conductivity but reduces the corrosion resistance. After the pretreatment and 30 min of nitridation, a thin film formed on the specimen surface, which mainly consists of Cr-nitrides and -oxides with atomic fractions of 0.42 and 0.37, respectively. The Cr-enriched and nitrided specimen shows spontaneous passivation in both the simulated cathode and anode environments and higher corrosion potentials, lower passive current densities, and larger polarization resistances in comparison with the directly nitrided specimens. Its stable current densities are about 0.26 and −0.39 μA cm−2 after 5 h of polarization tests at 0.6 VSCE in the cathode environment and at −0.1 VSCE in the anode environment, respectively. Its contact resistance is about 5.0 mΩ cm2 under 1.4 MPa, which is close to that of the specimen directly nitrided for 120 min and slightly decreases after the potentiostatic polarization tests. These results indicate that Cr-rich pretreatment improves not only the corrosion resistance and surface conductivity of nitrided specimens but also the efficiency of electrochemical nitridation. Full article
(This article belongs to the Special Issue Feature Paper Collection of “Current Challenges in Corrosion Research" (2nd Edition))
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13 pages, 1122 KiB  
Article
Physical Property Prediction of High-Temperature Nickel and Iron–Nickel Superalloys Using Direct and Inverse Composition Machine Learning Models
by Jaka Fajar Fatriansyah, Dzaky Iman Ajiputro, Agrin Febrian Pradana, Rio Sudwitama Persadanta Kaban, Andreas Federico, Muhammad Anis, Dedi Priadi and Nicolas Gascoin
Metals 2025, 15(5), 565; https://doi.org/10.3390/met15050565 - 21 May 2025
Abstract
Superalloys are a class of materials renowned for their exceptional ability to retain mechanical properties at elevated temperatures. Nickel superalloys, with a nickel content ranging from 38% to 76%, and iron–nickel superalloys (15–60% iron, 25–45% nickel) are extensively employed within the aviation industry [...] Read more.
Superalloys are a class of materials renowned for their exceptional ability to retain mechanical properties at elevated temperatures. Nickel superalloys, with a nickel content ranging from 38% to 76%, and iron–nickel superalloys (15–60% iron, 25–45% nickel) are extensively employed within the aviation industry due to their resilience in harsh operating environments. These components encounter extreme temperatures during operation, significantly impacting their tensile strength and melting point. Furthermore, high-speed rotation and abrasive conditions necessitate materials with superior hardness. Consequently, material modifications are crucial to ensure that gas turbine components meet their required properties. Machine learning (ML) and deep learning (DL) offer promising solutions for the design of materials with tailored tensile strength, hardness, and melting point properties. This study investigates the efficacy of direct and inverse machine learning models in predicting crucial material properties and composition, respectively. The model with the most favorable prediction accuracy is identified through the systematic variation of key parameters. The findings show that a fully connected feed-forward Artificial Neural Network (ANN) with three hidden layers using ReLU activation functions performs better than the other models. This capability is leveraged to modify the composition of INCONEL-718, successfully achieving significant enhancements in tensile strength (1592 MPa), hardness (152 HRB), and melting point (1665 °C). Full article
(This article belongs to the Section Structural Integrity of Metals)
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22 pages, 4310 KiB  
Review
The Microstructures and Properties of Cu-Ni-Co-Si Alloys: A Critical Review
by Fang Li, Wenteng Liu, Chao Ding, Shujuan Wang and Xiangpeng Meng
Metals 2025, 15(5), 564; https://doi.org/10.3390/met15050564 - 20 May 2025
Abstract
This review provides an overview of recent advancements in Cu-Ni-Co-Si alloys, focusing on their processing methods, microstructures, and properties. Due to their non-toxic composition, enhanced mechanical properties, and excellent electrical conductivity, Cu-Ni-Co-Si alloys have emerged as a promising alternative to traditional Cu-Be alloys [...] Read more.
This review provides an overview of recent advancements in Cu-Ni-Co-Si alloys, focusing on their processing methods, microstructures, and properties. Due to their non-toxic composition, enhanced mechanical properties, and excellent electrical conductivity, Cu-Ni-Co-Si alloys have emerged as a promising alternative to traditional Cu-Be alloys in the electrical and electronics industry. This review discusses various synthesis techniques, including casting, vacuum induction melting, and additive manufacturing, and evaluates their effects on the formed microstructures. In addition, it explores the influence of different elements and thermal treatments on the alloys’ microstructures and properties, discussing strategies to enhance the properties of Cu-Ni-Co-Si alloys. Key strengthening mechanisms—including precipitation hardening, grain boundary strengthening, and solid solution hardening—are examined in detail, with particular emphasis on their synergistic effects in optimizing alloy performance. Furthermore, future research directions are highlighted, focusing on the optimization of alloying element concentrations and heat treatment protocols to achieve an enhanced balance between strength and electrical conductivity. These improvements are critical for meeting the demanding requirements of advanced applications in electronics and high-reliability components. Full article
(This article belongs to the Special Issue Properties, Microstructure and Forming of Intermetallics)
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27 pages, 20326 KiB  
Article
Experimental and Numerical Investigation on Dynamic Shear Behavior of 30CrMnSiNi2A Steel Using Flat-Hat Specimens
by Xinke Xiao, Yuge Wang, Shuaitao Wu and Chuwei Zhou
Metals 2025, 15(5), 563; https://doi.org/10.3390/met15050563 - 20 May 2025
Abstract
An absolutely conflicting value for the incorporation of the Lode parameter into a fracture criterion was reported in the literature when predicting the ballistic resistance of metallic plates failing through shear plugging. In this study, a combined experimental–numerical investigation was conducted to understand [...] Read more.
An absolutely conflicting value for the incorporation of the Lode parameter into a fracture criterion was reported in the literature when predicting the ballistic resistance of metallic plates failing through shear plugging. In this study, a combined experimental–numerical investigation was conducted to understand the dynamic shear fracture behavior under compression–shear stress states. Flat-hat-shaped specimens of 30CrMnSiNi2A high-strength steel were loaded using a Split Hopkinson Pressure Bar apparatus, combining the ultra-high-speed photography technique, digital image correlation method, and microstructure observation. Parallel finite element simulations were performed using both a modified Johnson–Cook (MJC) fracture criterion or an extended Xue–Wierzbicki (EXW) fracture criterion with Lode dependence to reveal the value of the Lode parameter incorporation. It was found that deformed shear bands with a width of approximately 0.14 mm form at a critical impact velocity. The EXW criterion correctly predicts the critical fracture velocity and estimates the fracture initiation instants within an error of 5.3%, whereas the MJC fracture criterion overestimates the velocity by 14.3%. Detailed analysis shows that the EXW criterion predicts a combined failure mechanism involving ductile fracture and material instability, while the MJC fracture criterion attributes the failure exclusively to material instability. The improved accuracy achieved by employing the Lode-dependent EXW fracture criterion may be attributed to the compression–shear stress state and the accurate prediction of the failure mechanism of the dynamic shear fracture. Full article
(This article belongs to the Special Issue Deformation of Metals and Alloys: Theory, Simulations and Experiments—2nd Edition)
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15 pages, 3414 KiB  
Article
Geometric Analysis of the Scaling of the Manganese Recovery Process Using Current Distribution and Potential Simulation Techniques
by Esaú M. Rodríguez Vigueras, Victor E. Reyes Cruz, Felipe M. Galleguillos Madrid, José A. Cobos Murcia, Quinik L. Reyes Morales, Gustavo Urbano Reyes, Marissa Vargas Ramírez, Felipe Legorreta García and Marinka Varas
Metals 2025, 15(5), 562; https://doi.org/10.3390/met15050562 - 20 May 2025
Abstract
Electrolytic metallic manganese (EMM) is used as an alloying metal to provide resistance to abrasion and corrosion. Highly pure EMM is obtained through electrorecovery or electrowinning. Efforts are ongoing to improve the efficiency and profitability of this process, as 85 to 90% of [...] Read more.
Electrolytic metallic manganese (EMM) is used as an alloying metal to provide resistance to abrasion and corrosion. Highly pure EMM is obtained through electrorecovery or electrowinning. Efforts are ongoing to improve the efficiency and profitability of this process, as 85 to 90% of manganese is produced by the mining industry. This study applied computer-aided engineering (CAE) to provide information on the behavior of the potential distribution at the electrodes in cells separated by membranes, which allows for the optimization of the EMM production process. The experimental results obtained galvanostatically for EMM allowed for validation of the simulation parameters. It was determined that the cell with 11 compartments is more suitable compared to cells with fewer compartments, since it has lower oxidation-normalized current density and oxidation potential, which affect the distribution of cathodic potential in the process of obtaining EMM. The simulation highlighted a better distribution of the cathodic and anodic potentials due to the increase in the number of electrodes. This saves time and resources in the design of electrochemical cells with a greater number of compartments. Full article
(This article belongs to the Section Computation and Simulation on Metals)
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17 pages, 4575 KiB  
Article
Effects of TiC Addition on Mechanical Behavior and Cutting Performance of Powder Extrusion Printed Cemented Carbides
by Bisheng Zhong, Dezhi He, Xin Deng and Peishen Ni
Metals 2025, 15(5), 561; https://doi.org/10.3390/met15050561 - 19 May 2025
Abstract
This study addresses the limited research on the mechanical behavior and cutting performance of additive manufactured cemented carbides with high TiC content, which has impeded the rapid development of additive manufacturing in carbide cutting tools. Using powder extrusion printing (PEP) additive manufacturing technology, [...] Read more.
This study addresses the limited research on the mechanical behavior and cutting performance of additive manufactured cemented carbides with high TiC content, which has impeded the rapid development of additive manufacturing in carbide cutting tools. Using powder extrusion printing (PEP) additive manufacturing technology, we successfully fabricated WC-10TiC-12Co and WC-20TiC-12Co carbides with a relative density exceeding 97%. We investigated the effects of TiC content on the mechanical properties and cutting performance of WC-12Co carbide tools. The results show that TiC addition significantly affects the mechanical properties and cutting performance of PEP-processed carbides. Adding 10 wt.% and 20 wt.% TiC increases the Vickers hardness to 1403 HV30 and 1496 HV30, respectively, compared to 1317 HV30 for WC-12Co without TiC. However, TiC addition reduces the flexural strength from 2025 MPa for WC-12Co to 1434 MPa with 10 wt.% TiC and further to 915 MPa with 20 wt.% TiC. Tribological testing indicates that TiC addition reduces the friction coefficient and enhances wear resistance. HT250 cutting tests reveal that TiC addition significantly improves wear resistance and reduces workpiece surface roughness, particularly during longer cutting durations. This study broadens the scope of carbide materials suitable for PEP additive manufacturing. Full article
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7 pages, 160 KiB  
Editorial
Simulation and Optimization Methods in Machining and Structure/Material Design
by Wuyi Ming, Xiaoke Li and Wenbin He
Metals 2025, 15(5), 560; https://doi.org/10.3390/met15050560 - 19 May 2025
Viewed by 53
Abstract
Machining and structural/material design are fundamental pillars of modern manufacturing systems [...] Full article
(This article belongs to the Special Issue Simulation and Optimization Methods in Machining and Structure/Material Design)
13 pages, 2407 KiB  
Article
Study of the Effect of Tin Addition in Aluminum–Copper Alloys Obtained from Elemental Powders
by Pedro José Olendski Elias Junior, Ederson Bitencourt das Neves, Luciano Volcanoglo Biehl, Ismael Cristofer Baierle, Carlos Otávio Damas Martins and Jorge Luis Braz Medeiros
Metals 2025, 15(5), 559; https://doi.org/10.3390/met15050559 - 19 May 2025
Viewed by 50
Abstract
Powder metallurgy enables the production of composite materials, which are of great interest to different branches of the automotive, aerospace, and medical industries. This work investigated the sintering of an Al-xCu and Al-xCu-0.1Sn alloy, with copper concentration between 3.5 and 4.5% and tin [...] Read more.
Powder metallurgy enables the production of composite materials, which are of great interest to different branches of the automotive, aerospace, and medical industries. This work investigated the sintering of an Al-xCu and Al-xCu-0.1Sn alloy, with copper concentration between 3.5 and 4.5% and tin added in the range of 0.1%. Compressibility curves were drawn, and the samples were sintered in a high-purity nitrogen-controlled atmosphere furnace. The composites were subjected to subsequent solubilization heat treatment, with cooling in low concentration polymer solutions and artificial aging (T6). The samples were studied using optical, scanning electron, Vickers microhardness, and X-ray diffraction techniques. The results indicated the effectiveness of cooling the samples after solubilization in polymer solutions, the influence of the addition of tin on the aging time, and the mechanical properties of the alloys as a function of the T6 cycles applied. Full article
(This article belongs to the Special Issue Fabricating Advanced Metallic Materials)
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15 pages, 3303 KiB  
Article
The Effects of ECAP and Recovery Treatment on the Microstructure and the Mechanical, Tribological, and Corrosion Properties of 316L Steel
by Ata Radnia, Mostafa Ketabchi, Anqiang He, Guijiang Diao and Dongyang Li
Metals 2025, 15(5), 558; https://doi.org/10.3390/met15050558 - 19 May 2025
Viewed by 47
Abstract
316L steel is widely used in various industries and is also one of the metallic materials used for biomedical applications because of its excellent mechanical properties, corrosion resistance, and biocompatibility. This article reports a comprehensive study on the effects of equal channel angular [...] Read more.
316L steel is widely used in various industries and is also one of the metallic materials used for biomedical applications because of its excellent mechanical properties, corrosion resistance, and biocompatibility. This article reports a comprehensive study on the effects of equal channel angular pressing (ECAP) and subsequent recovery treatment on the microstructure and the mechanical, tribological, and corrosion properties of 316L. The process includes an initial annealing at 1050 °C for 2 h to obtain a homogenous microstructure, ECAP at room temperature with a 120° inner angle, and subsequent recovery treatment at 340 °C for 1 h. The microstructure was investigated with an optical microscope and a transmission electron microscope. The mechanical properties were evaluated with hardness and compression tests. The corrosion behavior was analyzed with dynamic polarization tests. The wear test was performed using a scratching tester, and the volume loss was measured with a profilometer. The results of the study demonstrate that the ECAP–recovery sample exhibits improved properties compared to both the annealed sample and the ECAP sample. The corrosion tests show that the ECAP sample has a corrosion resistance higher than that of the annealed sample but lower than that of the ECAP–recovery sample. The ECAP–recovery sample shows the highest wear resistance and corrosive wear resistance among the three samples. Full article
(This article belongs to the Section Metal Casting, Forming and Heat Treatment)
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21 pages, 10936 KiB  
Article
Bonding Strength and Its Enhancing Mechanism of CuCr/In718 Dissimilar Materials with Mortise and Tenon Structure Interface Manufactured by Laser-Based Direct Energy Deposition (DED-LB) Using Powder Feedstock
by Gang Xu and Hongmei Zhang
Metals 2025, 15(5), 557; https://doi.org/10.3390/met15050557 - 19 May 2025
Viewed by 52
Abstract
The interface bonding strength is challenging for CuCr and In718 dissimilar alloys fabricated by Laser-Based Direct Energy Deposition (DED-LB) using Powder Feedstock. Here, direct-bonded CuCr/In718 dissimilar materials (DMs) (direct-bonded specimen) and CuCr/In718 DMs with mortise and tenon structure interface (mortise-tenon specimen) were deposited [...] Read more.
The interface bonding strength is challenging for CuCr and In718 dissimilar alloys fabricated by Laser-Based Direct Energy Deposition (DED-LB) using Powder Feedstock. Here, direct-bonded CuCr/In718 dissimilar materials (DMs) (direct-bonded specimen) and CuCr/In718 DMs with mortise and tenon structure interface (mortise-tenon specimen) were deposited by powder DED-LB. Owing to the alternating inter-track and inter-layer remelting, the defects were avoided, and the Cu elemental diffusion was obvious in the mortise-tenon specimen. Thereby, the better metallurgical bonding strength was achieved in the mortise-tenon specimen. The sandwich-shaped microstructure, including fine equiaxed and columnar grains, and the heterogeneous microstructure consisting of large columnar, short columnar, and fine equiaxed grains were formed in direct-bonded and mortise-tenon specimens, respectively. The formation mechanisms of these microstructures were unveiled, respectively. Besides, the shear strength of direct-bonded and mortise-tenon specimens was investigated. Owing to the mortise and tenon structure, the ultimate shear strength (USS) was increased by 47.18%. The synergistic enhancing mechanism of macroscopic interfacial morphology, microstructure, and elemental distribution on shear strength was revealed. Full article
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16 pages, 12762 KiB  
Article
Impact of Melt Refining on Secondary Al-Si Alloys’ Microstructure and Tensile Mechanical Performance
by Wei Gu, Huixin Jin, Xue Wang and Jiajun Jiang
Metals 2025, 15(5), 556; https://doi.org/10.3390/met15050556 - 18 May 2025
Viewed by 118
Abstract
Secondary Al-Si alloys typically encompass several impurities that substantially influence the materials’ microstructure and mechanical performance. This study employed a composite addition of chlorinated salt fluxing and an aluminum–boron master alloy to reduce the levels of the impurity elements magnesium (Mg), titanium (Ti), [...] Read more.
Secondary Al-Si alloys typically encompass several impurities that substantially influence the materials’ microstructure and mechanical performance. This study employed a composite addition of chlorinated salt fluxing and an aluminum–boron master alloy to reduce the levels of the impurity elements magnesium (Mg), titanium (Ti), and vanadium (V) in secondary Al-Si alloys. The investigation of the performance mechanism revealed that the distribution of alloys’ grain orientation and the ratio of small-angle grain boundaries were modified via synergistic purification, leading to the refined microstructure and mechanical performance of secondary Al-Si alloys. The removal rates of impurity elements under these optimal refining conditions were 89.9% for Mg, 68.9% for Ti, and 61.5% for V. The refined alloy exhibited a 45.5% decrease in grain size and a 28.7% improvement in tensile strength compared to the raw material. These findings demonstrate that fluxing can improve the extraction of Ti and V from secondary Al-Si alloy melts of aluminum–boron master alloys, providing a new cost-effective strategy for the removal of impurities and the optimization of the properties of secondary Al-Si alloys. Full article
(This article belongs to the Section Metal Casting, Forming and Heat Treatment)
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11 pages, 883 KiB  
Article
Rate Equation Analysis of the Effect of Damage Distribution on Defect Evolution in Self-Ion Irradiated Fe
by Toshimasa Yoshiie
Metals 2025, 15(5), 555; https://doi.org/10.3390/met15050555 - 17 May 2025
Viewed by 121
Abstract
Ion irradiations have a damage peak near the beam incident surface. A simulation model with reaction kinetic analysis using rate equations was employed to study the defect evolution caused by localized damage distribution in self-ion irradiated iron. Comparisons were made between the localized [...] Read more.
Ion irradiations have a damage peak near the beam incident surface. A simulation model with reaction kinetic analysis using rate equations was employed to study the defect evolution caused by localized damage distribution in self-ion irradiated iron. Comparisons were made between the localized damage irradiation by ions (the damage peak near the specimen surface) and homogeneous damage irradiation (the flat damage rate across the specimen) such as those caused by neutron irradiation. The irradiation conditions were as follows: the accelerating voltage was 2 MeV and 100 MeV, the irradiation temperatures was 273 K and 573 K, the damage rate was 1 × 10−5 dpa/s, and the total damage was 1 dpa. The distribution of residual point defects in clusters is complex due to the influence of the surface and the sharp distribution of the damage peak. The effects of the damage distributions on defect production were obtained, revealing a dependence on irradiation temperatures. At 573 K irradiation, localized damage irradiation produced higher residual interstitials than homogeneous damage irradiation when using the peak damage rate. The 100 MeV irradiation was more prominent than 2 MeV irradiation. However, the remaining vacancies were almost identical. At 273 K irradiation, the residual point defects, interstitials, and vacancies, were nearly identical in both the localized and homogeneous damage irradiations, even if the accelerating voltage was different. Full article
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13 pages, 4362 KiB  
Article
The Effect of N/O Elements on the Microstructure and Mechanical Properties of Ti-N-O Alloys
by Mingqi Shi, Ruiduo Chen, Chengsong Zhang, Zhenzhao Xu, Hanke Hu, Xiaolong Zhou and Guodong Cui
Metals 2025, 15(5), 554; https://doi.org/10.3390/met15050554 - 17 May 2025
Viewed by 142
Abstract
A novel Ti-N-O composite was prepared by powder nitriding/oxynitriding combined with the spark plasma sintering (SPS) method. The effects of N/O on the microstructure and mechanical properties of the Ti-N-O alloy were systematically studied. The results showed that the addition of N/O elements [...] Read more.
A novel Ti-N-O composite was prepared by powder nitriding/oxynitriding combined with the spark plasma sintering (SPS) method. The effects of N/O on the microstructure and mechanical properties of the Ti-N-O alloy were systematically studied. The results showed that the addition of N/O elements significantly improved the mechanical properties of commercially pure titanium (cp-Ti). The hardness reached 298.8 HV0.1 while the yield strength can reach 666 MPa. And, the O element played a leading role in regulating the microstructure and morphology of the Ti-N-O alloy. With the addition of the O element, the microstructure showed an equiaxed structure, and the characterization showed that this region is an O-enriched region, and that a small amount of nano-TiO2 particles appeared in the alloy, which together led to the change in the microstructure. At the same time, more large-angle grain boundaries were generated in the Ti-N-O alloy. This study investigated a new method for the preparation of titanium materials and provides new ideas for researching medical titanium materials. Full article
(This article belongs to the Special Issue Heat Treatment, Microstructures, and Mechanical Properties of Metallic Materials)
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11 pages, 6552 KiB  
Article
Isothermal Oxidation Kinetics of Iron Powders Under Vapor Atmosphere
by Wenchao He, Jian Chen, Yin Deng and Zhiming Yan
Metals 2025, 15(5), 553; https://doi.org/10.3390/met15050553 - 16 May 2025
Viewed by 37
Abstract
Semisteel is the byproduct of the titania slag smelting process of ilmenite concentrate with an electric furnace. To enhance the added value of semisteel, a centrifugal granulation–water curtain process was adopted to manufacture iron powders. The oxidation characteristics of granulated powders were analyzed [...] Read more.
Semisteel is the byproduct of the titania slag smelting process of ilmenite concentrate with an electric furnace. To enhance the added value of semisteel, a centrifugal granulation–water curtain process was adopted to manufacture iron powders. The oxidation characteristics of granulated powders were analyzed by thermogravimetry (TG), X-ray diffraction (XRD), and scanning electron microscopy (SEM). To obtain iron powders with high purity, the isothermal oxidation kinetics of pure iron powders under vapor atmosphere were studied. TG measurements of pure iron powders were conducted at 1073 K, 1173 K, and 1273 K using a humidity generating instrument and a thermal analyzer. The results indicate that the oxidation rate increases with the increasing temperature and decreasing powder size. The entire isothermal oxidation process of iron powders with different sizes (0.3 mm < d1 < 0.35 mm, 0.4 mm < d2 < 0.45 mm, and 0.5 mm < d3 < 0.55 mm) comprises two stages. The first oxidation stage is controlled by chemical reaction; the second oxidation stage is controlled by both internal diffusion and chemical reaction. The activation energies and oxidation reaction rate equations of iron powders at different stages are calculated. Full article
(This article belongs to the Special Issue Advanced Metal Smelting Technology and Prospects)
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33 pages, 5594 KiB  
Review
Research Progress of Ternary Cathode Materials: Failure Mechanism and Heat Treatment for Repair and Regeneration
by Tingting Wu, Chengxu Zhang and Jue Hu
Metals 2025, 15(5), 552; https://doi.org/10.3390/met15050552 - 16 May 2025
Viewed by 51
Abstract
With the large-scale application of lithium-ion batteries in the field of new energy, many retired lithium batteries not only cause environmental pollution problems but also lead to serious waste of resources. Repairing failed lithium batteries and regenerating new materials has become a crucial [...] Read more.
With the large-scale application of lithium-ion batteries in the field of new energy, many retired lithium batteries not only cause environmental pollution problems but also lead to serious waste of resources. Repairing failed lithium batteries and regenerating new materials has become a crucial path to break through this dilemma. Based on the research on the failure mechanism of ternary cathode materials, this paper systematically combs through the multiple factors leading to their failure, extensively summarizes the influence of heat treatment process parameters on the performance of recycled materials, and explores the synergistic effect between heat treatment technology and other processes. Studies have shown that the failure of ternary cathode materials is mainly attributed to factors such as cation mixing disorder, the generation of microcracks, phase structure transformation, and the accumulation of by-products. Among them, cation mixing disorder damages the crystal structure of the material, microcracks accelerate the pulverization of the active substance, phase structure transformation leads to lattice distortion, and the generation of by-products will hinder ion transport. The revelation of these failure mechanisms lays a theoretical foundation for the efficient recycling of waste materials. In terms of recycling technology, this paper focuses on the application of heat treatment technology. On the one hand, through synergy with element doping and surface coating technologies, heat treatment can effectively improve the crystal structure and surface properties of the material. On the other hand, when combined with processes such as the molten salt method, coprecipitation method, and hydrothermal method, heat treatment can further optimize the microstructure and electrochemical properties of the material. Specifically, heat treatment plays multiple key roles in the recycling process of ternary cathode materials: repairing crystal structure defects, enhancing the electrochemical performance of the material, removing impurities, and promoting the uniform distribution of elements. It is a core link to achieving the efficient reuse of waste ternary cathode materials. Full article
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21 pages, 8416 KiB  
Article
First-Principles Calculations of the Effect of Ta Content on the Properties of UNbMoHfTa High-Entropy Alloys
by Yue Lin, Tao Wang, Jintao Wang, Wanxiao Guo, Weiyi Li, Yuheng Li and Hongbo Qiu
Metals 2025, 15(5), 551; https://doi.org/10.3390/met15050551 - 16 May 2025
Viewed by 46
Abstract
Uranium-containing high-entropy alloys (HEAs) exhibit great potential as a novel energetic structural material, attributed to their excellent performance in impact energy release, superior mechanical properties, and high density. This study investigates the effects of Ta content on the phase stability, lattice constant, density, [...] Read more.
Uranium-containing high-entropy alloys (HEAs) exhibit great potential as a novel energetic structural material, attributed to their excellent performance in impact energy release, superior mechanical properties, and high density. This study investigates the effects of Ta content on the phase stability, lattice constant, density, elastic constants, polycrystalline moduli, and electronic structure of (UNbMoHf)54−xTax high-entropy alloys (where x = 2, 6, 10, 14, 18), utilizing a combination of density functional theory (DFT) calculations and the special quasi-random structure (SQS) approach. Our findings confirm that these alloys maintain stable body-centered cubic structures, as evidenced by atomic radius difference and valence electron concentration evaluations. Analysis of elastic modulus, Cauchy pressure, and Vickers hardness indicates that Ta incorporation enhances mechanical properties and increases the anisotropy of these alloys. Furthermore, investigations into the electronic structure reveal that adding Ta reduces metallic character while increasing covalent characteristics, enhancing the contribution of Ta’s d-orbitals to the total density of states and intensifying covalent bonding interactions between Ta and other elements such as Nb, Mo, and U. These findings provide theoretical guidance for the design of high-performance UNbMoHfTa HEAs with tailored properties. Full article
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14 pages, 5095 KiB  
Article
Performance Study of CaO-CaF2- and CaO-Al2O3-SiO2-Based High-Efficiency Desulfurizers
by Ruihong Cao, Shengtao Qiu, Ting Wu and Haijun Wang
Metals 2025, 15(5), 550; https://doi.org/10.3390/met15050550 - 16 May 2025
Viewed by 63
Abstract
In order to reduce the content of harmful impurity sulfur elements in steel to meet the quality requirements of high value-added steel, efficient desulfurization of RH vacuum degassing is essential. Based on the simplex lattice composition design method, the effects of typical compositions [...] Read more.
In order to reduce the content of harmful impurity sulfur elements in steel to meet the quality requirements of high value-added steel, efficient desulfurization of RH vacuum degassing is essential. Based on the simplex lattice composition design method, the effects of typical compositions on liquidus temperature, sulfur capacity, melting temperature, the effects of typical compositions on liquidus temperature, sulfur capacity, melting temperature, viscosity, and desulfurization rate of CaO-CaF2- and CaO-Al2O3-SiO2-based desulfurizers were studied by thermodynamic calculation, the melting temperature test, and the slag–steel contact experiment. The results show that in CaO-CaF2- and CaO-Al2O3-SiO2-based desulfurizers, the changes in CaF2, MgO, and Al2O3 contents has little effect on the equilibrium S content of molten steel at lower SiO2 contents, whereas, at higher SiO2 contents, the equilibrium S content of the molten steel is greatly increased when the CaF2, MgO, and Al2O3 content is greater than a certain value. Meanwhile, the increase in CaF2 and MgO content reduces the high-temperature viscosity and breaking temperature (corresponding to the turning point on the viscosity–temperature curve) to varying degrees, which results in a better slag fluidity and is favorable to the prevention of crusting. With the increase in Al2O3 and SiO2 content, the breaking temperature of the CaO-CaF2-based desulfurizer is significantly reduced, which is beneficial to preventing crust. However, when the breaking temperature of CaO-Al2O3-SiO2-based desulfurizer increases, part of the slag system has solidified at 1400 °C, which is easy to lead to slag crust when the temperature drops. Comprehensively, for the CaO-CaF2-based desulfurizer, CaO = 60 wt%, CaF2 = 30 wt%, SiO2 = 0–5 wt%, and add a small amount of Al2O3 and MgO, its desulfurization effect is significant. For the CaO-Al2O3-SiO2-based desulfurizer, CaO = 39–57 wt%, Al2O3 = 20–35 wt%, SiO2 = 10–15 wt%, MgO = 4 wt%, CaF2 = 4–8 wt%, its desulfurization effect meets the demand, and it can reduce equipment erosion and environmental pollution. Full article
(This article belongs to the Special Issue Green Super-Clean Steels)
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16 pages, 13005 KiB  
Article
Investigation of Microstructural Evolution of Silicon Steel Weldment After Post-Weld Heat Treatment—Simulation and Experimental Study
by Jyun-Ting Kuo, Chih-Hsien Chi, Ming-Feng Chiang, Te-Kang Tsao, Wei-Lin Hsu and An-Chou Yeh
Metals 2025, 15(5), 549; https://doi.org/10.3390/met15050549 - 15 May 2025
Viewed by 104
Abstract
It is important to control the microstructure and properties of a weld for the continuous production of silicon steel sheets. Post-weld heat treatment (PWHT) can be applied to adjust the weld properties; however, research on its application to silicon steel weldments remains limited. [...] Read more.
It is important to control the microstructure and properties of a weld for the continuous production of silicon steel sheets. Post-weld heat treatment (PWHT) can be applied to adjust the weld properties; however, research on its application to silicon steel weldments remains limited. This study investigated the microstructure and hardness evolution of the weld after PWHT for high-silicon steel, with Inconel 82 used as the filler material. The weldment contained FCC phase and BCC phase regions, and PWHT were conducted at 520, 620, 720, and 920 °C for 8 h. Experimental observations indicate that G-phase precipitations in FCC phase could increase its hardness, and it peaked at 620 °C with an average hardness of 259 HV. By contrast, the BCC phase region was subjected to martensitic transformation and its hardness increased from 305 to 335 HV after PWHT at 920 °C. To elucidate microstructure evolutions, CALPHAD-based simulations successfully predicted BCC to FCC phase transformation at 920 °C, peak G-phase precipitation at 620 °C, and elemental diffusion at the BCC and FCC interface. The findings indicate that CALPHAD-based simulations offer a robust approach that can be extended to understand the effect of PWHT. Full article
(This article belongs to the Special Issue Editorial Board Members’ Collection Series: “Welding and Joining”)
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20 pages, 10057 KiB  
Article
An Investigation of Heat Treatment Residual Stress of Type I, II, III for 8Cr4Mo4V Steel Bearing Ring Using FEA-CPFEM-GPA Method
by Tao Xia, Puchang Cui, Tianpeng Song, Xue Liu, Yong Liu and Jingchuan Zhu
Metals 2025, 15(5), 548; https://doi.org/10.3390/met15050548 - 15 May 2025
Viewed by 164
Abstract
The heat treatment residual stress of 8Cr4Mo4V steel bearings seriously affects the contact fatigue life. The micro stress concentration at the carbide interface leads to the initiation of micro cracks. Therefore, in this paper, the systematic analysis of heat treatment residual stress of [...] Read more.
The heat treatment residual stress of 8Cr4Mo4V steel bearings seriously affects the contact fatigue life. The micro stress concentration at the carbide interface leads to the initiation of micro cracks. Therefore, in this paper, the systematic analysis of heat treatment residual stress of 8Cr4Mo4V steel is conducted. FEA was used to analyze the residual stress of type I after heat treatment process. Based on numerical simulation and EBSD results, CPFEM was carried out to study the distribution of type II residual stress. Using high-resolution characterization results, GPA was performed to study type III residual stress caused by crystal defects. The FEA results indicate that thermal strain and phase transformation strain dominate the macroscopic stress change before and after martensitic transformation. During the first tempering process, the phase transformation leads to the release of quenching residual stress. The large stress concentration at the carbide interface is revealed by CPFEM. High-resolution characterization of coherent interface between carbide and matrix reveals that the micro residual strain at this interface is small. Through a systematic analysis of the residual stress of 8Cr4Mo4V steel, a basis is provided for modifying the macroscopic and microscopic residual stress of heat treatment to improve the bearing performance. Full article
(This article belongs to the Special Issue Research on Microstructure and Performance Mechanisms of Advanced Steels and Alloys)
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19 pages, 9986 KiB  
Article
Effect of Laser Welding Parameters on Similar and Dissimilar Joints for Tab–Busbar Interconnects
by Mari Carmen Taboada, Mariane Chludzinski, Raul Gómez and Egoitz Aldanondo
Metals 2025, 15(5), 547; https://doi.org/10.3390/met15050547 - 15 May 2025
Viewed by 110
Abstract
The demand for electric mobility has driven the development of advanced laser welding technologies such as dual beam welding and beam shaping. Nevertheless, some intrinsic characteristics present challenges to exploring all its benefits. In this sense, this study investigates the effect of the [...] Read more.
The demand for electric mobility has driven the development of advanced laser welding technologies such as dual beam welding and beam shaping. Nevertheless, some intrinsic characteristics present challenges to exploring all its benefits. In this sense, this study investigates the effect of the laser welding parameters employed on the weld quality in busbar–battery interconnects. Dual beam and beam shaping strategies were applied in Al-Al (AA1050 H24) and Al-Cu (AA1050 H24 and C11000) overlap joint configurations adopting statistical methods. For Al-Al joints, welding speed was the most significant parameter influencing interface width, whereas in Al-Cu joints, core power was the only significant parameter affecting both interface width and penetration in the studied configuration. Common defects, such as porosity and cracks, were observed in both material combinations. In Al-Al joints, higher welding speeds resulted in up to a 16% (65.6 HV) increase in hardness, while, in Al-Cu joints, the peak value reached around 900 HV in the interface zone due to the formation of intermetallic compounds (IMCs). In addition, IMCs with complex structures and significant compositional variations, including Cu9Al4 and CuAl2 were identified. Full article
(This article belongs to the Special Issue Welding and Joining Technology of Dissimilar Metal Materials)
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13 pages, 2612 KiB  
Article
Application of Bayesian Statistics in Analyzing and Predicting Carburizing-Induced Dimensional Changes in Torsion Bars
by Guojin Sun, Zhenggui Li, Yanxiong Jiao and Qi Wang
Metals 2025, 15(5), 546; https://doi.org/10.3390/met15050546 - 15 May 2025
Viewed by 153
Abstract
This study investigates the application of Bayesian statistical methods to analyze and predict the dimensional changes in torsion bars made from 20CrMnTi alloy steel during carburizing heat treatment. The process parameters, including a treatment temperature of 920 °C followed by oil quenching, were [...] Read more.
This study investigates the application of Bayesian statistical methods to analyze and predict the dimensional changes in torsion bars made from 20CrMnTi alloy steel during carburizing heat treatment. The process parameters, including a treatment temperature of 920 °C followed by oil quenching, were selected to optimize surface hardness while maintaining core toughness. The dimensional changes were measured pre- and post-treatment using precise caliper measurements. Bayesian statistics, particularly conjugate normal distributions, were utilized to model the dimensional variations, providing both posterior and predictive distributions. These models revealed a marked concentration of the posterior distributions, indicating enhanced accuracy in predicting dimensional changes. The findings offer valuable insights for improving the control of carburizing-induced deformations, thereby ensuring the dimensional integrity and performance reliability of torsion bars used in high-stress applications such as pneumatic clutch systems in mining ball mills. This study underscores the potential of Bayesian approaches in advancing precision engineering and contributes to the broader field of statistical modeling in manufacturing processes. Full article
(This article belongs to the Special Issue Numerical and Experimental Advances in Metal Processing)
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14 pages, 7472 KiB  
Article
Improved Microstructure of 316LN Stainless Steel Performed by Ultrasonic Surface Rolling
by Likun Jiang, Xingwang Feng, Huanchun Wu, Guosheng Su and Bin Yang
Metals 2025, 15(5), 545; https://doi.org/10.3390/met15050545 - 14 May 2025
Viewed by 127
Abstract
316LN stainless steel (316LN SS) with a gradient structure was produced by ultrasonic surface rolling processing (USRP). The surface quality of the 316LN SS specimen was improved significantly after the USRP. The experimental results showed that with an increasing number of rolling passes, [...] Read more.
316LN stainless steel (316LN SS) with a gradient structure was produced by ultrasonic surface rolling processing (USRP). The surface quality of the 316LN SS specimen was improved significantly after the USRP. The experimental results showed that with an increasing number of rolling passes, the thickness of the gradient structure layer increased, and the microhardness decreased in a gradient from the surface to the matrix. The results also indicated that the optimal parameters were as follows: 220 rad/min lathe speed, 0.11 mm rolling space, 0.2 rad/min feed rate, and 5 rolling passes. Under these parameters, the tested surface residual compressive stress (SRCS) value was nearly 32 times higher than that achieved after conventional processing on the surface of 316LN stainless steel. Moreover, the microstructure exhibits an increase in the subgrain boundary density and low-angle grain boundaries (LAGBs, misorientation < 15°) of the steel, providing an easy way to enhance the properties, including the mechanical and corrosion resistance of 316LN stainless steel. Full article
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16 pages, 11733 KiB  
Article
Springback Control of Profile by Multi-Point Stretch-Bending and Torsion Automatic Forming Based on FE-BPNN
by Yu Wen, Jicai Liang, Yi Li and Ce Liang
Metals 2025, 15(5), 544; https://doi.org/10.3390/met15050544 - 14 May 2025
Viewed by 120
Abstract
Springback control is a critical factor in profile stretch-bending-torsion forming. A new stretch-bending-torsion automatic forming method based on the mixture of finite element and BP neural network (FE-BPNN) is proposed. The method enhances the shape accuracy of profiles after single-step forming. Initially, the [...] Read more.
Springback control is a critical factor in profile stretch-bending-torsion forming. A new stretch-bending-torsion automatic forming method based on the mixture of finite element and BP neural network (FE-BPNN) is proposed. The method enhances the shape accuracy of profiles after single-step forming. Initially, the study introduces the 3D multi-point stretch-bending and torsion (3D MPSBT) forming machine and its forming principles. Subsequently, it details the springback prediction method and automatic forming control approach based on BPNN. A springback control model is established through numerical simulation and experiments. The proposed springback control method is compared with a springback factor-based approach from other researchers using hollow rectangular profiles undergoing combined bending and torsion deformation as the research object. The results validate the effectiveness and advantages of the proposed method. Full article
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11 pages, 2594 KiB  
Article
Influence of Deposition Rate on Fatigue Behavior of 316L Stainless Steel Prepared via Hybrid Laser Wire Direct Energy Deposition
by Md Abu Jafor, Ryan Kinser, Ning Zhu, Khaled Matalgah, Paul G. Allison, J. Brian Jordon and Trevor J. Fleck
Metals 2025, 15(5), 543; https://doi.org/10.3390/met15050543 - 14 May 2025
Viewed by 115
Abstract
Hybrid additive manufacturing (AM) provides a unique way of fabricating complex geometries with onboard machining capabilities, combining both additive and traditional subtractive techniques and resulting in reduced material waste and efficient high-tolerance components. In this work, a hybrid AM technology was used to [...] Read more.
Hybrid additive manufacturing (AM) provides a unique way of fabricating complex geometries with onboard machining capabilities, combining both additive and traditional subtractive techniques and resulting in reduced material waste and efficient high-tolerance components. In this work, a hybrid AM technology was used to create 316L stainless steel (316L SS) components using laser-wire-directed energy deposition (LW-DED) coupled with a CNC machining center on a single platform. Fully reversed fatigue tests were completed to investigate the as-manufactured life span of the additively manufactured structures for three different deposition rates of 6.33 g/min, 7.12 g/min, and 7.91 g/min. High-cycle fatigue test results showed that the fatigue performance of the tested specimens is not dependent on the deposition rates for the investigated parameters, with specimens with a 7.12 g/min deposition rate showing comparatively superior behavior to that of the other deposition rates at higher stress amplitudes. Fractography analysis was used to investigate the fractured surfaces, showing that the crack initiation sites were predominantly near the edges and not affected by the volumetric defects generated during manufacturing. X-ray-computed tomography (X-ray CT) analysis quantified the effect of the as-manufactured porosity on fatigue behavior, showing that the amount of porosity for the build rates used was insufficient to have a substantial impact on the fatigue behavior, even as it increased with the deposition rate. Full article
(This article belongs to the Section Additive Manufacturing)
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25 pages, 4373 KiB  
Review
Numerical Simulation and Hot Isostatic Pressing Technology of Powder Titanium Alloys: A Review
by Jianglei Cui, Xiaolong Lv and Hanguang Fu
Metals 2025, 15(5), 542; https://doi.org/10.3390/met15050542 - 14 May 2025
Viewed by 167
Abstract
Titanium and its alloys have been widely used in high-end fields such as aerospace and biomedical engineering due to their excellent corrosion resistance and comprehensive mechanical properties. However, traditional titanium alloy processing technologies suffer from low material utilization and numerous defects. The emergence [...] Read more.
Titanium and its alloys have been widely used in high-end fields such as aerospace and biomedical engineering due to their excellent corrosion resistance and comprehensive mechanical properties. However, traditional titanium alloy processing technologies suffer from low material utilization and numerous defects. The emergence of near-net shape forming technology for powder titanium alloys via hot isostatic pressing (HIP) has broken through the limitations of traditional casting and forging, significantly improving the mechanical properties of titanium alloy materials, increasing material utilization, and shortening the production cycle of products. The application of numerical simulation technology has provided a scientific basis for the design of capsules and cores of complex high-performance components and has offered theoretical support for the densification of powders under thermomechanical coupling, becoming an essential foundation for achieving controllable shape and properties of components. This paper introduces the characteristics and process flow of HIP technology for powder titanium alloys, summarizes the current development status and research achievements of this technology both domestically and internationally, elaborates on the research progress of numerical simulation of HIP, and concludes with an analysis of the existing technological challenges and possible solutions, as well as an outlook on future development directions. Full article
(This article belongs to the Special Issue Microstructure and Mechanical Properties of Metallic Materials by Powder Metallurgy)
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24 pages, 13691 KiB  
Article
Microstructure and Properties of Mooring Chain Steel Prepared by Selective Laser Melting
by Xiaojie Cui, Xiaoxin Li, Changqing Hu, Dingguo Zhao, Yan Liu and Shuhuan Wang
Metals 2025, 15(5), 541; https://doi.org/10.3390/met15050541 - 14 May 2025
Viewed by 138
Abstract
22MnCrNiMo steel, a high-strength low-alloy material, is primarily used in the production of mooring chains for offshore oil platforms, offshore wind turbines, and ships. The application of additive manufacturing technology allows for the direct fabrication of seamless mooring chains. This paper investigates the [...] Read more.
22MnCrNiMo steel, a high-strength low-alloy material, is primarily used in the production of mooring chains for offshore oil platforms, offshore wind turbines, and ships. The application of additive manufacturing technology allows for the direct fabrication of seamless mooring chains. This paper investigates the selective laser melting (SLM) process parameters for 22MnCrNiMo mooring chain steel, analyzing the effects of different process parameters on the microstructure, phase composition, and mechanical properties of the steel. The experimental results demonstrate that under the laser parameters of 200 W laser power, 800 mm/s scanning speed, 30 μm layer thickness, and 110 μm scanning spacing, the SLM-formed parts exhibit the best comprehensive mechanical properties, with a microhardness of 513.2 HV0.5, a tensile strength of 1223 MPa, a yield strength of 1114 MPa, an elongation of 8.5%, and an impact energy of 127 J. This study reveals the microstructure evolution and the mechanism of enhanced mechanical properties in SLM-fabricated 22MnCrNiMo steel, providing a new approach for the preparation of high-performance mooring chains using 22MnCrNiMo steel. Full article
(This article belongs to the Special Issue Manufacturing Processes of Metallic Materials)
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17 pages, 8207 KiB  
Article
Optimization of Roll Configuration and Investigation of Forming Process in Three-Roll Planetary Rolling of Stainless Steel Seamless Tubes
by Chuanchuan Ma, Tuo Li, Chun Xue, Ri Jin, Zhibing Chu, Meirong Shuai and Leifeng Tuo
Metals 2025, 15(5), 540; https://doi.org/10.3390/met15050540 - 13 May 2025
Viewed by 151
Abstract
Three-roll planetary rolling technology has emerged as a primary method for manufacturing seamless tubes due to its advantages, including significant single-pass deformation, low energy consumption, and the ability to continuously roll long workpieces. Based on the forming characteristics of three-roll planetary rolling, this [...] Read more.
Three-roll planetary rolling technology has emerged as a primary method for manufacturing seamless tubes due to its advantages, including significant single-pass deformation, low energy consumption, and the ability to continuously roll long workpieces. Based on the forming characteristics of three-roll planetary rolling, this study established a simulation model of the rolling process, which includes key parameters such as the friction coefficient, roll speed, and roll deflection angle. Using finite element software, the effects of these parameters on the rolling process are simulated and analyzed. By comparing critical indicators such as the equivalent stress, rolling temperature, and roundness of the workpiece, the influence of the process parameters on the forming quality of three-roll planetary rolling is revealed. The optimal parameter combination is determined as follows: a friction coefficient of 0.3, roll speed of 120 rpm, and roll deflection angle of 9°. This research provides a reliable theoretical foundation for subsequent roll profile design and process parameter optimization in three-roll planetary rolling. Full article
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