-
Effect of Heat Treatments and Related Microstructural Modifications on High-Cycle Fatigue Behavior of Powder Bed Fusion–Laser Beam-Fabricated Ti-6Al-2Sn-4Zr-6Mo Alloy -
Point Defects in MoNbTi-Based Refractory Multi-Principal-Element Alloys -
Residual Stress and Corrosion Performance in L-PBF Ti6Al4V: Unveiling the Optimum Stress Relieving Temperature via Microcapillary Electrochemical Characterisation -
The Effect of Mo and Al Substitution in Cryomilled and Cold-Rolled FeNi Alloys
Journal Description
Metals
Metals
is an international, peer-reviewed, open access journal published monthly online by MDPI. The Portuguese Society of Materials (SPM), and the Spanish Materials Society (SOCIEMAT) are affiliated with Metals and their members receive discounts on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, Ei Compendex, CAPlus / SciFinder, and other databases.
- Journal Rank: JCR - Q2 (Metallurgy and Metallurgical Engineering) / CiteScore - Q1 (Metals and Alloys)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 18 days after submission; acceptance to publication is undertaken in 2.6 days (median values for papers published in this journal in the first half of 2025).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Companion journals for Metals include: Compounds and Alloys.
Impact Factor:
2.5 (2024);
5-Year Impact Factor:
2.8 (2024)
Latest Articles
Comparative Study on Reduction in Oolitic High-Phosphorus Iron-Ore Lumps and Pellets Under H2 Atmosphere
Metals 2025, 15(12), 1319; https://doi.org/10.3390/met15121319 (registering DOI) - 28 Nov 2025
Abstract
High-phosphorus iron ore can be utilized using a technical route of hydrogen-based shaft furnace reduction, followed by electric arc furnace (EAF) melting separation. In shaft furnace reduction, both pellet and lump ore could serve as feedstock. To optimize the charge pattern in the
[...] Read more.
High-phosphorus iron ore can be utilized using a technical route of hydrogen-based shaft furnace reduction, followed by electric arc furnace (EAF) melting separation. In shaft furnace reduction, both pellet and lump ore could serve as feedstock. To optimize the charge pattern in the H2-based shaft furnace, an investigation of the reduction behavior of high-phosphorus iron ore lumps and pellets under H2 atmosphere was conducted. Results revealed distinct differences between the lumps and the pellets in terms of physicochemical characteristics, maximum reduction fractions, microstructure evolution, and reduction kinetics characteristics. The lumps exhibited a notable presence of oolitic structures with 60.08 wt.% total iron, 11.69 wt.%. Fe2+ ion, and 0.80 wt.% phosphorus. Under H2 atmosphere, the lumps achieved a maximum reduction fraction of 0.80. During the reduction, fayalite formed in the early stage, and glassy phases appeared in the later stage. The rate-controlling steps included internal gas diffusion, interfacial chemical reaction, and solid-state diffusion of ions. In contrast, the oolitic structures were completely disrupted in the pellets. The pellets contained 56.01 wt.% total iron, 0.86 wt.% Fe2+ ions, and 0.73 wt.% phosphorus. The pellets reached a full reduction under H2 atmosphere with negligible formation of fayalite and glassy phases. The rate-controlling steps included internal gas diffusion and interfacial chemical reaction.
Full article
(This article belongs to the Special Issue Recent Developments in Ironmaking)
Open AccessArticle
Resource-Efficient Smelting Technology for FeCrMnSi Ferroalloy Production from Technogenic Wastes in an Ore-Thermal Furnace
by
Yerbolat Makhambetov, Armat Zhakan, Ablay Zhunusov, Sultan Kabylkanov, Azamat Burumbayev, Zhadiger Sadyk, Amankeldy Akhmetov and Bagdagul Uakhitova
Metals 2025, 15(12), 1318; https://doi.org/10.3390/met15121318 (registering DOI) - 28 Nov 2025
Abstract
►▼
Show Figures
The article presents the results of a study on the production of a complex chromium–manganese–silicon-containing ferroalloy in a large-scale laboratory ore-thermal furnace using man-made waste—chromium-containing aspiration dust obtained during smelting of high-carbon ferrochrome, fines (−5 mm) of iron–manganese ore currently stored in landfills,
[...] Read more.
The article presents the results of a study on the production of a complex chromium–manganese–silicon-containing ferroalloy in a large-scale laboratory ore-thermal furnace using man-made waste—chromium-containing aspiration dust obtained during smelting of high-carbon ferrochrome, fines (−5 mm) of iron–manganese ore currently stored in landfills, and finely dispersed coal sludge formed during enrichment. A single-stage technology for the production of a new complex chromium–manganese–silicon-containing ferroalloy by carbothermal reduction is proposed. A metallurgical assessment of the initial charge materials was carried out by the X-ray diffraction (XRD) phase analysis, and metal samples of the obtained ferroalloy were studied by scanning electron microscopy (SEM) in combination with energy dispersive spectroscopy (EDS). The resulting ferroalloy has a complex microstructure with a predominance of carbide and intermetallic phases. A high degree of extraction of chromium (up to 80%), manganese (up to 75%), and silicon (up to 35%) was recorded. The average chemical composition of the obtained ferroalloy, wt.%: Cr—37.41; Mn—17.31; Si—11.84; C—3.81; P—0.14; S—0.02. The slag formed during the smelting of the ferroalloy has satisfactory technological properties: it is characterized by good fluidity, and it actively exits the furnace by gravity. Entanglement of metal kings in the slag is not observed. The results obtained confirm the technological feasibility of the utilization of technogenic raw materials for the production of complex ferroalloys of the FeCrMnSi type.
Full article

Figure 1
Open AccessArticle
Mechanistic Insights into Spatially Resolved Molten Pool Dynamics and Energy Coupling in CMT-WAAM of 316L Stainless Steel
by
Jun Deng, Chen Yan, Xuefei Cui, Chuang Wei and Ji Chen
Metals 2025, 15(12), 1317; https://doi.org/10.3390/met15121317 (registering DOI) - 28 Nov 2025
Abstract
This study investigated the influence of spatial orientation on bead morphology and molten pool dynamics during cold metal transfer wire arc additive manufacturing (CMT-WAAM). Experiments in horizontal, transverse, vertical-down, and vertical-up orientations under varying wire feed speeds revealed that increasing the feed
[...] Read more.
This study investigated the influence of spatial orientation on bead morphology and molten pool dynamics during cold metal transfer wire arc additive manufacturing (CMT-WAAM). Experiments in horizontal, transverse, vertical-down, and vertical-up orientations under varying wire feed speeds revealed that increasing the feed rate improved bead uniformity and reduced defects in horizontal deposition, while gravity-induced asymmetry dominated non-horizontal orientations. Transverse cladding produced tilted, uneven beads with reduced penetration; vertical-down enhanced lateral spreading but resulted in the shallowest weld depth; vertical-up limited spreading, yielding narrow beads with higher reinforcement. Optimal cladding quality was achieved at a wire feed speed of 6.7 m/min for the first layer, with a reduced heat input applied for subsequent layers to minimize residual stress and deformation. Numerical simulations further elucidated transient temperature and flow fields. Heat accumulation and dissipation varied with orientation and layer sequence: horizontal deposition formed deep, symmetric pools; transverse deposition generated asymmetric vortices and uneven solidification; vertical-up deposition caused upward counterflow with restricted spreading; vertical-down promoted rapid spreading and faster solidification. A detailed comparison between simulated and experimental temperature distributions and cross-sectional profiles demonstrated excellent agreement, thereby validating the accuracy and predictive capability of the developed model. This integrated experimental-numerical approach provided a comprehensive understanding of orientation-dependent molten pool behavior and offered a robust framework for optimizing process parameters, enhancing dimensional accuracy, and controlling defects in CMT additive manufacturing.
Full article
Open AccessArticle
Effect of Axial Stress on Torsional Behavior for Extruded AZ31 Mg Alloys Under Multiaxial Loading
by
Chong Yang, Baocheng Yang, Guoguo Zhu, Muyu Li, Liangbin Chen, Yanpu Chao, Yaohui Li and Ruju Fang
Metals 2025, 15(12), 1316; https://doi.org/10.3390/met15121316 (registering DOI) - 28 Nov 2025
Abstract
The torsional behavior of an extruded AZ31 magnesium alloy was investigated by combined axial-torsion mechanical testing with different stress ratios. The SEM-EBSD was used to analyze the microstructure and texture evolution of deformed samples. The results indicate that the axial tension results in
[...] Read more.
The torsional behavior of an extruded AZ31 magnesium alloy was investigated by combined axial-torsion mechanical testing with different stress ratios. The SEM-EBSD was used to analyze the microstructure and texture evolution of deformed samples. The results indicate that the axial tension results in a concave-down shape of shear stress–strain curves, while a concave-up shape after yielding is presented during combined compression-torsion loading due to twinning mechanism. Compared to pure shear, the yield strength decreases by 7 MPa and shear strain increases by 1% under σ:τ = −1:1 with same shear stress. Due to the Swift effect, a strain partitioning is displayed for axial strain during combined tension-torsion loading with low stress ratio. The twin volume fraction is 90% under σ:τ = −1:1, and the local dislocation density with a KAM value of 1.1 is maximum under σ:τ = 2:1. The primary twin type is {10-12} twins with axial compression. The main deformation mode changes from basal slip to prismatic slip with increase in axial tension stress. Both basal slip and twinning are activated and the interaction between dislocation slip and twinning contributes to the complex strain hardening behavior during combined compression-torsion loading.
Full article
Open AccessReview
Metallic Mechanical Metamaterials Produced by LPBF for Energy Absorption Systems
by
Gabriele Grima, Kamal Sleem, Gianni Virgili, Alberto Santoni, Maria Laura Gatto, Stefano Spigarelli, Marcello Cabibbo and Eleonora Santecchia
Metals 2025, 15(12), 1315; https://doi.org/10.3390/met15121315 (registering DOI) - 28 Nov 2025
Abstract
Metallic mechanical metamaterials have attracted the attention of many industrial sectors due to their unique properties which enable them to outperform natural materials in unconventional ways. Metal metamaterials encompass multiple fields, including materials science, mechanics, and industrial technology, and they have become particularly
[...] Read more.
Metallic mechanical metamaterials have attracted the attention of many industrial sectors due to their unique properties which enable them to outperform natural materials in unconventional ways. Metal metamaterials encompass multiple fields, including materials science, mechanics, and industrial technology, and they have become particularly popular following the implementation of reliable, high-resolution, efficient metal additive manufacturing processes. This review takes a joint approach, providing an in-depth analysis of the base materials and geometries that characterize metamaterials in order to understand their behavior in response to impacts at different load regimes and to offer readers a critical overview of the most suitable design choices for energy absorption systems. Furthermore, this review highlights advanced metamaterial optimization methods that are useful for increasing the mechanical energy absorbed avoiding peak impulse transfer to the people, instrumentation, or generic loads that mechanical metamaterials are designed to protect.
Full article
(This article belongs to the Special Issue Recent Advances in Powder-Based Additive Manufacturing of Metals)
Open AccessArticle
Effects of Chemical Composition on Welding HAZ Softening of High-Strength Pipeline Steels
by
Yu Gu, Xiao-Wei Chen, He-He Kang, Cheng-Guang Zhang, Zong-Xuan Wang and Fu-Ren Xiao
Metals 2025, 15(12), 1314; https://doi.org/10.3390/met15121314 (registering DOI) - 28 Nov 2025
Abstract
With the increase in strength of pipeline steels manufactured by thermomechanical control process (TMCP), the softening of the welding heat-affected zone (HAZ) becomes another important factor affecting the properties of welded steel pipes and the safety of pipeline operation. In this work, based
[...] Read more.
With the increase in strength of pipeline steels manufactured by thermomechanical control process (TMCP), the softening of the welding heat-affected zone (HAZ) becomes another important factor affecting the properties of welded steel pipes and the safety of pipeline operation. In this work, based on the actual welding process of steel pipes, the strength, phase transformation, and microstructure of the HAZ of six pipeline steels with different chemical compositions were studied by using a thermomechanical simulator, and the effect of chemical composition on the softening of HAZ was discussed. Results show that the strength of HAZs is significantly influenced by the peak temperature, and the softening zone mainly occurs in fine-grained HAZ (FGHAZ) when peak temperature is 900~1000 °C. Meanwhile, the degree of softening is also affected by the chemical composition of the steels. The effects of peak temperature and chemical composition of the steels on the strength of the HAZs when the peak temperature is over Ac3 are attributed to their effect on the austenite transformation during the heating process, and then the effect on phase transformation during the cooling process and final microstructure. The strength of the HAZs is linearly related to the beginning phase temperature during the cooling process, and the strength of sub-HAZs at the same peak temperature is linearly related to the value of carbon equivalent (Ceq) of steels. Therefore, controlling the appropriate value of Ceq is necessary to improve the softening of HAZs for high-strength pipeline steels.
Full article
(This article belongs to the Special Issue Advances in Welding and Joining of Alloys and Steel)
►▼
Show Figures

Figure 1
Open AccessArticle
Experimental and Numerical Investigation on Fracture Behavior and Energy Absorption Characteristics of Aluminum Foam in the Taylor Tests
by
Chenyang Fan, Xingyu Dong, Youcai Xiao and Wenzhong Lou
Metals 2025, 15(12), 1313; https://doi.org/10.3390/met15121313 (registering DOI) - 28 Nov 2025
Abstract
This study investigates the dynamic response characteristics of aluminum foam materials under low to medium-high velocity impact loading, elucidating their deformation mechanisms and energy absorption capabilities through an integrated experimental and numerical simulation approach. The multi-stage deformation behavior of aluminum foam was investigated
[...] Read more.
This study investigates the dynamic response characteristics of aluminum foam materials under low to medium-high velocity impact loading, elucidating their deformation mechanisms and energy absorption capabilities through an integrated experimental and numerical simulation approach. The multi-stage deformation behavior of aluminum foam was investigated through the Taylor impact test, which demonstrated that impact velocity significantly affects its stiffness and energy absorption capability. The accuracy of stress distribution and mechanical properties during the impact process is validated, and the deformation behavior under medium- and high-speed impact conditions is clearly revealed. Through integrated macroscopic and microscopic analyses, the dynamic response characteristics of aluminum foam under various impact loads are systematically investigated, elucidating the mechanisms of internal pore collapse and dynamic compressive behavior, thereby providing robust theoretical support for the optimized design of aluminum foam in cushioning and protective applications.
Full article
(This article belongs to the Section Corrosion and Protection)
►▼
Show Figures

Figure 1
Open AccessArticle
Simultaneous Solvent Extraction of Co and Ni from Copper Raffinate Waste Solution
by
Hanieh Rezaei, Mohammad Reza Aboutalebi, Seyed Hossein Seyedein, Hossein Aghajani and Marek Wojnicki
Metals 2025, 15(12), 1312; https://doi.org/10.3390/met15121312 (registering DOI) - 28 Nov 2025
Abstract
The extraction and stripping of Co, Ni, Mn, and Mg ions from raffinate solution of the Sarcheshmeh copper complex containing Cu (0.14 g/L), Ni (0.15 g/L), Co (0.06 g/L), Fe (10.72 g/L), Zn (2.4 g/L), Mn (4.83 g/L), and Mg (8 g/L) was
[...] Read more.
The extraction and stripping of Co, Ni, Mn, and Mg ions from raffinate solution of the Sarcheshmeh copper complex containing Cu (0.14 g/L), Ni (0.15 g/L), Co (0.06 g/L), Fe (10.72 g/L), Zn (2.4 g/L), Mn (4.83 g/L), and Mg (8 g/L) was comprehensively studied using D2EHPA and LIX 984 extractants. To design the solvent extraction experiments, the response surface method (RSM) was employed. The optimal and most efficient conditions and extraction rates of nickel and cobalt were considered for the application of a central composite design (CCD). The design of experiments (DOE) was carried out using three operating variables: the equilibrium pH of the solution (4–6), extractant concentration (10–20%), and aqueous-to-organic phase ratio (1–3). The results indicated that the highest extraction of Co and Ni occurred within 5 min at a mixing speed of 500 r/min and 40 °C. The results showed that the equilibrium pH of the aqueous solution had a greater influence on nickel and cobalt extraction than the other parameters. According to the research results, 99% of cobalt and 94% of nickel were extracted simultaneously under optimum conditions of pH = 6, [LIX984N] = 10%, and A/O = 3. In the stripping stage, 95% of nickel ions were recovered in one step using 1 M sulfuric acid, and 80% of cobalt ions were recovered in three steps using 5 M hydrochloric acid. Finally, 98% of Zn, 99% of Co, and 94% of Ni were extracted in two stages with D2EHPA and LIX984N extractants.
Full article
(This article belongs to the Special Issue Hydrometallurgical Processes for the Recovery of Critical Metals)
►▼
Show Figures

Figure 1
Open AccessCorrection
Correction: Wang et al. Experimental Study on Backwater-Assisted Picosecond Laser Trepanning of 304 Stainless Steel. Metals 2025, 15, 1138
by
Liang Wang, Rui Xia, Jie Zhou, Yefei Rong, Changjian Wu, Long Xu, Xiaoxu Han and Kaibo Xia
Metals 2025, 15(12), 1311; https://doi.org/10.3390/met15121311 - 28 Nov 2025
Abstract
In the original publication [...]
Full article
Open AccessArticle
Study on Cold Cracking in 430Cb Ferritic Stainless Steel Castings Based on Multiscale Characterization and Simulation Analysis
by
Siyu Qiu, Jun Xiao and Aimin Zhao
Metals 2025, 15(12), 1310; https://doi.org/10.3390/met15121310 - 28 Nov 2025
Abstract
Cracks were found at the gate of the 430Cb ferritic stainless steel exhaust system jet base produced by investment casting. In this paper, the cracks of failed stainless steel castings were comprehensively analyzed by means of macroscopic inspection, laser confocal microscopy, field emission
[...] Read more.
Cracks were found at the gate of the 430Cb ferritic stainless steel exhaust system jet base produced by investment casting. In this paper, the cracks of failed stainless steel castings were comprehensively analyzed by means of macroscopic inspection, laser confocal microscopy, field emission scanning electron microscopy, electron backscatter diffraction, X-ray diffractometer, ProCAST (version 2018, ESI Group, Paris, France) simulation and Thermo-Calc (TCFE10 database, 2022a, Thermo-Calc Software AB, Solna, Sweden) thermodynamic calculation. It can be concluded that all the cracks originate from the gate on the surface of the casting, and the fracture surface shows brittle intergranular characteristics, which can be determined as cold cracks. The formation of cold cracks can be attributed to the fact that the local stress generated during cooling after the casting solidifies exceeds the strength limit of the material itself. As the gate is the final solidification zone, shrinkage is limited and stress is concentrated. The grains are coarse, and the microstructure defects such as shrinkage porosity, pores and needle-like NbC further weaken the plasticity of the grain boundaries, promoting the crack to propagate along the direction of the maximum principal stress. The uneven cooling rate and shell constraint during the investment casting process make it difficult to release stress, and the existence of microstructure defects are the fundamental causes of crack generation.
Full article
(This article belongs to the Special Issue Innovations in Heat Treatment of Metallic Materials)
►▼
Show Figures

Figure 1
Open AccessArticle
On the Effect of Multi-Pass Friction Stir Processing on Microstructure-Tensile Deformation Behavior Relationships in Cast Al-7%Si-0.4%Mg Specimens
by
Murat Tiryakioğlu, Nelson Netto and Paul D. Eason
Metals 2025, 15(12), 1309; https://doi.org/10.3390/met15121309 - 28 Nov 2025
Abstract
►▼
Show Figures
Specimens from commercial and continuously cast A356 ingots have been friction stir-processed, and tensile deformation has been characterized. These two types of ingots have been found to be damaged in the liquid state, but at different levels. In both cases, the microstructure has
[...] Read more.
Specimens from commercial and continuously cast A356 ingots have been friction stir-processed, and tensile deformation has been characterized. These two types of ingots have been found to be damaged in the liquid state, but at different levels. In both cases, the microstructure has been refined and homogenized. FSP has been found to improve structural quality by breaking up bifilms. For the commercial ingot, each FSP pass has progressively improved structural quality, as evidenced by an 18 times increase in elongation (from 1.0 to 18.8% after three passes), whereas in the continuously cast ingot, it has taken only one pass for FSP to improve structural quality by doubling elongation (from 10.9 to 21.1%) after which additional passes have not resulted in further improvement. Analysis of tensile deformation behavior has shown that all FSPed specimens exhibit a distinct Stage III work hardening, as modeled by Kocks and Mecking. Through the analysis of tensile deformation behavior, it has been hypothesized that improvement in elongation and structural quality with FSP may not be solely attributed to the refinement of Si particles.
Full article

Figure 1
Open AccessArticle
Alkali Fusion–Leaching Process for Non-Standard Copper Anode Slime (CAS)
by
Jovana Djokić, Nataša Gajić, Dragana Radovanović, Marija Štulović, Stevan Dimitrijević, Nela Vujović and Željko Kamberović
Metals 2025, 15(12), 1308; https://doi.org/10.3390/met15121308 - 27 Nov 2025
Abstract
Copper anode slime (CAS), obtained from non-standard anodes by pyro-hydrometallurgical electronic waste (e-waste) processing, contains high concentrations of lead, tin (as metastannic acid), and base (Cu, Fe, Zn), precious (Au, Ag), and technological metals (In, Ga, Ge), which limit the efficiency of conventional
[...] Read more.
Copper anode slime (CAS), obtained from non-standard anodes by pyro-hydrometallurgical electronic waste (e-waste) processing, contains high concentrations of lead, tin (as metastannic acid), and base (Cu, Fe, Zn), precious (Au, Ag), and technological metals (In, Ga, Ge), which limit the efficiency of conventional valorization methods. In this study, an integrated alkali fusion–leaching process was applied to non-standard CAS. Thermodynamic modeling defined the key parameters for selective phase transformations and efficient metal separation. These parameters were experimentally investigated, and the optimized fusion conditions (CAS:NaOH = 40:60, 600 °C, 60 min), followed by water leaching (200 g/dm3, 80 °C, 60 min, 250 rpm), resulted in >97% Sn removal efficiency. Simultaneously, Au and Ag losses were negligible, resulting in solid residue enrichment. Oxidant addition (NaNO3) did not improve Sn removal but increased Fe, Pb, and Ag solubility, reducing selectivity. The scaled-up test confirmed process reproducibility, achieving 97.75% Sn dissolution and retention of precious metals in the PbO-based residue (99.99% Au, 99.78% Ag). Application of an integrated thermodynamic modeling, laboratory optimization, and scaled-up validation approach to non-standard CAS provides a relevant framework for a selective, efficient, and scalable method addressing industrial needs driven by increased e-waste co-processing, contributing to sustainable metal recovery.
Full article
(This article belongs to the Special Issue Hydrometallurgical Processes for the Recovery of Critical Metals)
►▼
Show Figures

Graphical abstract
Open AccessArticle
Statistical Evaluation of the Mechanical Properties of Welded and Unwelded ASTM A706 Reinforcing Steel Bars of Different Commercial Brands
by
Lenin Abatta-Jacome, Daniel Rosero-Pazmiño, Jeison Rosero-Vivas, Bryan Fernando Chávez-Guerrero and Germán Omar Barrionuevo
Metals 2025, 15(12), 1307; https://doi.org/10.3390/met15121307 - 27 Nov 2025
Abstract
The future of reinforcing steel bars (rebar) is being shaped by technological advancements, sustainability initiatives, and evolving construction practices. Welding of rebar has a significant and evolving influence on construction practices, particularly with trends emphasizing speed, precision, and prefabrication. On the other hand,
[...] Read more.
The future of reinforcing steel bars (rebar) is being shaped by technological advancements, sustainability initiatives, and evolving construction practices. Welding of rebar has a significant and evolving influence on construction practices, particularly with trends emphasizing speed, precision, and prefabrication. On the other hand, the variability in mechanical response depends not only on the chemical composition but also on the manufacturing and welding process. This study analyzed five commercial brands of ASTM A706 reinforcing steel rods available in the Ecuadorian market with different diameters (12, 14, 16, and 18 mm) subjected to tensile and bending tests. A total of 228 specimens were analyzed, and 114 samples were welded by shielded metal arc welding process using an E8018-C3 electrode, preparing the joint with a simple V-bevel at 45°. The tensile tests results allow for a comparison between the welded and unwelded steel bars, where it is identified that the welding process generates a slight decrease in the mechanical properties and increases the variability in the results, although it is emphasized that these variations do not affect compliance with the standards, since all the samples meet the mechanical strength requirements by being within the limits established by the ASTM A706/A706M standard.
Full article
(This article belongs to the Special Issue Failure Analysis and Evaluation of Metallic Materials)
►▼
Show Figures

Figure 1
Open AccessArticle
Temperature Based Fatigue Damage Entropy for Assessment of High-Cycle Fatigue in Laser-Welded Joints
by
Yang Liu, Yang Sun and Xinhua Yang
Metals 2025, 15(12), 1306; https://doi.org/10.3390/met15121306 - 27 Nov 2025
Abstract
To quickly predict the fatigue strength of welded joints in high-cycle fatigue tests and fit the S-N curve, this paper proposes a new model based on infrared thermal imaging technology. High-cycle fatigue tests were conducted on laser-welded joints of weathering steel Q450NQR1 and
[...] Read more.
To quickly predict the fatigue strength of welded joints in high-cycle fatigue tests and fit the S-N curve, this paper proposes a new model based on infrared thermal imaging technology. High-cycle fatigue tests were conducted on laser-welded joints of weathering steel Q450NQR1 and separately, on joints made of stainless steel T4003, while local temperature variations in the joints were monitored. Based on the experimentally observed temperature drop behavior, a novel Temperature-Drop-Curve-Based Fatigue Damage Entropy (TDC-FDE) model was developed to rapidly estimate the fatigue life and fatigue limit of welded joints. The model quantifies the entropy generated during fatigue damage evolution based on the temperature-decrease slope and establishes a direct relationship between entropy and the fatigue performance of the joint using this slope as the linking parameter. Experimental results indicate that a material’s specific heat capacity, density, elastic modulus, and applied stress level directly influence fatigue damage entropy generation. The entropy increase associated with purely elastic deformation does not contribute to fatigue damage in high-cycle fatigue; therefore, this portion should be excluded from the fatigue damage entropy calculation. The fatigue damage entropy of a given weld joint tends to remain nearly constant under different stress levels and loading frequencies. Finally, traditional fatigue tests demonstrated that the maximum deviation between the fatigue strength predicted by the proposed model and the experimentally measured values does not exceed 3.4%, thereby verifying the model’s accuracy and effectiveness in evaluating fatigue performance.
Full article
Open AccessArticle
Numerical Investigation of Dual Vertical Water Jets Impinging on High-Temperature Steel
by
Jianhui Shi, Zhao Zhang, Xiangfei Ji, Jinwen You and Feng Han
Metals 2025, 15(12), 1305; https://doi.org/10.3390/met15121305 - 27 Nov 2025
Abstract
►▼
Show Figures
The flow dynamics and heat transfer of dual vertical water jets impinging a high-temperature steel plate were numerically investigated using a three-dimensional model. A systematic parametric investigation was conducted by varying key operating conditions: including the jet velocity at the nozzle exit (
[...] Read more.
The flow dynamics and heat transfer of dual vertical water jets impinging a high-temperature steel plate were numerically investigated using a three-dimensional model. A systematic parametric investigation was conducted by varying key operating conditions: including the jet velocity at the nozzle exit (V = 5 m/s, 7.5 m/s, 10 m/s), the non-dimensional nozzle-to-plate distance (H = h/d = 3.3, 5.8, 8.3, 10.8), and the non-dimensional spacing between twin nozzles (W = w/d = 5, 7.5, 10). Upon impingement, multiple wall-jet flows formed on the steel plate surface, with their radial spread distance increasing along the plate’s surface. A wall-jet interaction zone developed between the two jets, accompanied by a linear fountain upwash flow. To depict the thermal and hydrodynamic characteristics, the distributions of the local Nusselt number and flow velocity vectors were examined. Findings suggest that fluctuations in W have little impact on the mean Nusselt number. Nevertheless, a growth in H brings about a concurrent increase in the Nusselt number of the stagnation point on the plate’s surface. Furthermore, the results indicate that W is a primary factor controlling the heat transfer rate within the interaction zone of the opposing wall jets.
Full article

Figure 1
Open AccessReview
Advances in Microstructural Evolution and Mechanical Properties of Magnesium Alloys Under Shear Deformation
by
Yaqing Liu, Yong Xue and Zhaoming Yan
Metals 2025, 15(12), 1304; https://doi.org/10.3390/met15121304 - 27 Nov 2025
Abstract
Magnesium (Mg) alloys are the lightest metals used in engineering structures, making them highly valuable for lightweight designs in aerospace, automotives, and related industries. Their low density offers clear advantages for reducing product weight and improving energy efficiency–key priorities in modern manufacturing. However,
[...] Read more.
Magnesium (Mg) alloys are the lightest metals used in engineering structures, making them highly valuable for lightweight designs in aerospace, automotives, and related industries. Their low density offers clear advantages for reducing product weight and improving energy efficiency–key priorities in modern manufacturing. However, their unique crystal structure leads to notable drawbacks: low plasticity at room temperature, uneven performance across different directions, and inconsistent strength under tension versus compression. These issues have severely limited their broader application beyond specialized use cases. Shear deformation methods address this challenge by creating high strain variations and complex stress conditions. This approach provides an effective way to regulate the internal structure of Mg alloys and enhance their overall performance, overcoming the inherent limitations of their crystal structure. This paper systematically summarizes current research on using shear deformation to process Mg alloys. It focuses on analyzing key structural changes induced by shear, including the formation and evolution of shear–related features, real–time grain reorganization, crystal twinning processes, the distribution of additional material phases, and reduced directional performance bias. The review also clarifies how these structural changes improve critical mechanical traits: strength, plasticity, formability, and the balance between tensile and compressive strength. Additionally, the paper introduces advanced shear–based processes and their derivative technologies, such as equal–channel angular extrusion, continuous shear extrusion, and ultrasonic vibration–assisted shearing. It also discusses strategies for constructing materials with gradient or mixed internal structures, which further expand the performance potential of Mg alloys. Finally, the review outlines future development directions to advance this field: developing shear processes that combine multiple physical fields, conducting real–time studies of microscale mechanisms, designing tailored shear paths for high–performance Mg alloys, and evaluating long–term service performance. These efforts aim to promote both theoretical innovation and industrial application of shear deformation technology for Mg alloys.
Full article
(This article belongs to the Special Issue Novel Insights into Wrought Magnesium Alloys)
►▼
Show Figures

Figure 1
Open AccessArticle
A New Microcrack Characterisation Method for Quench Cracking in Induction-Hardened Steels
by
A. Aysu Catal-Isik, Lizeth J. Sanchez, Mangesh Pantawane, Vikram Bedekar and Enrique I. Galindo-Nava
Metals 2025, 15(12), 1303; https://doi.org/10.3390/met15121303 - 27 Nov 2025
Abstract
High-performance induction-hardened bearing steels are prone to quench cracking during manufacturing, causing significant material and energy waste. Understanding the physics behind microcracking is essential to the design of alloys and processes with reduced cracking behaviour. However, conventional quench crack analysis methods provide information
[...] Read more.
High-performance induction-hardened bearing steels are prone to quench cracking during manufacturing, causing significant material and energy waste. Understanding the physics behind microcracking is essential to the design of alloys and processes with reduced cracking behaviour. However, conventional quench crack analysis methods provide information only on crack severity and neither link martensite microstructure to microcrack formation or provide meaningful insights on the origins of microcracking. Therefore, this work introduces a new crack quantification method that assesses various crack features, including crack length, location within a martensite plate, crack angle to the plate midrib, and the distance from the induction-hardened surface. It is found that microcrack severity changes with the distance from the induction-hardened surface, peaking at ∼1 mm in depth, with a maximum density of approximately 1000 cracks per mm2. In addition, microcracks are mostly seen in the martensite plates rather than at the austenite–martensite interface, with the majority lying perpendicular to the midrib. Approximately 50% of the interfacial cracks are oriented at an angle less than 10 °C to the martensite midrib and are mainly located around the midpoint of the interface. Martensite plates having interfacial cracks are mostly 10–20 μm long, whereas martensite plates with internal cracks are mostly 20–30 μm long. The new method helps build quantitative links between microcracking and martensite morphology to study the mechanisms of cracking and the role of the initial microstructure in more detail.
Full article
(This article belongs to the Special Issue Advances in Steels: Heat Treatment, Microstructure and Properties)
►▼
Show Figures

Figure 1
Open AccessArticle
Temperature-Correlated Characterization of EoL Lithium Cobalt Oxide Batteries with Microwave-Based Pyrometallurgical Recovery
by
Emma Pitacco, Marco Ragazzini, Caterina Bernardini, Mehran Ghadimi, Mirko Pigato, Michele Forzan and Katya Brunelli
Metals 2025, 15(12), 1302; https://doi.org/10.3390/met15121302 - 26 Nov 2025
Abstract
With the increasing volumes of spent lithium-ion batteries from electric vehicles and the concurrent increase in raw materials cost for cathode production, finding effective methods for recycling battery materials has become critically important. This study investigated a pyrometallurgical approach using microwave irradiation to
[...] Read more.
With the increasing volumes of spent lithium-ion batteries from electric vehicles and the concurrent increase in raw materials cost for cathode production, finding effective methods for recycling battery materials has become critically important. This study investigated a pyrometallurgical approach using microwave irradiation to achieve carbothermal reduction of LiCoO2. FactSage thermodynamic calculations were performed for process simulation and an infrared thermal camera was employed for temperature measurements, allowing the authors to optimize the process parameters to obtain metallic cobalt. Specifically, the research included microwave experiments on mixed black mass samples of anode and cathode materials in different proportions, treated at varying power levels and exposure times under air atmosphere. The effect of the process parameters and therefore of the temperature on microstructure was studied with SEM-EDS and XRD analysis. The feasibility of a wet magnetic separation method between cobalt and lithium compounds formed during the reaction was also evaluated. The results obtained from the final separation process indicated that individual compounds can be obtained at the end of the cycle; moreover, the optimization of time, temperature, and graphite additions during the tests allowed the authors to obtain promising results.
Full article
(This article belongs to the Special Issue Current Trends in Non-Ferrous Metals Extraction, Separation, and Refining)
►▼
Show Figures

Figure 1
Open AccessArticle
Enhancing Automotive Valve Guide Tribomechanical Performance Through Alloy Optimization in Powder Metallurgy
by
Fujian Guo, Zhongyuan Yan, Guangyi Lu, Wenle Liu, Pan Zhang and Gengzhe Shen
Metals 2025, 15(12), 1301; https://doi.org/10.3390/met15121301 - 26 Nov 2025
Abstract
►▼
Show Figures
Given the critical role of valve guides in the performance and lifespan of automotive engines, it is crucial to understand and improve their wear resistance. This study focuses on the wear resistance of powder metallurgy valve guides, aiming to systematically analyze the intrinsic
[...] Read more.
Given the critical role of valve guides in the performance and lifespan of automotive engines, it is crucial to understand and improve their wear resistance. This study focuses on the wear resistance of powder metallurgy valve guides, aiming to systematically analyze the intrinsic relationship between their composition, microstructure, and properties. Three powder metallurgy valve guide samples with different compositions—specifically, a high-MoS2 Fe-C-Mo-Cu-S alloy (1.5 wt.% C, 1.9 wt.% Mo, 1.5 wt.% Cu, 1.4 wt.% S), a low-MoS2 Fe-C-Mo-Cu-S alloy (1.2 wt.% C, 0.3 wt.% Mo, 0.8 wt.% Cu, 0.2 wt.% S), and a Mo-free high-C-Cu Fe-C alloy (1.8 wt.% C, 5 wt.% Cu, 0 wt.% Mo, 0.01 wt.% S)—were studied using field emission scanning electron microscopy, metallographic microscopy, a reciprocating friction testing machine, and a 3D optical profilometer. The results show that the friction coefficient of the high-MoS2 Fe-C-Mo-Cu-S alloy is the highest at 0.5, the low-MoS2 Fe-C-Mo-Cu-S alloy is 0.25, and the Mo-free high-C-Cu Fe-C alloy is the lowest at 0.22. Since the minor wear amount cannot be accurately measured by the gravimetric method, the concave area of the wear-induced average roughness curve is employed to qualitatively indicate the magnitude of material loss: the area of the high-MoS2 Fe-C-Mo-Cu-S alloy is 2964 μm2, the low-MoS2 Fe-C-Mo-Cu-S alloy is 1580 μm2, and the Mo-free high-C-Cu Fe-C alloy is 1502 μm2. The hardness results of the material show that the high-MoS2 Fe-C-Mo-Cu-S alloy reaches 154 HB, the low-MoS2 Fe-C-Mo-Cu-S alloy is 134 HB, and the Mo-free high-C-Cu Fe-C alloy is 145 HB. The porosity results show a difference of about 2% among the three alloys. Based on the microstructure characterization results, it can be concluded that the Mo-free high-C-Cu Fe-C alloy—with high carbon (C) and copper (Cu) content and fine pearlite layers—exhibits excellent wear resistance: high C can improve the hardness of the matrix, while Cu can act as a lubricating phase to enhance the material’s wear resistance. In contrast, although the addition of MoS2 is intended to improve wear resistance, the irregular pearlite generated by MoS2 reduces the wear resistance of the high-MoS2 and low-MoS2 Fe-C-Mo-Cu-S alloys; among them, the high-MoS2 Fe-C-Mo-Cu-S alloy contains a higher amount of MoS2, and large chunks appearing in the tissue easily cause abrasive wear and aggravate material wear during friction. This study provides solid theoretical and practical support for the material selection and performance optimization of powder metallurgy engine valve guides: the identified intrinsic relationship between alloy composition (MoS2, C, and Cu contents), microstructure (pearlite morphology and second-phase distribution), and tribological performance establishes a clear theoretical basis for regulating the wear resistance of such components.
Full article

Figure 1
Open AccessArticle
Probabilistic Modeling of Fatigue Life Prediction of Notched Specimens Combining Highly Stressed Volume and Theory of Critical Distance Approach
by
Bin Li, Peng Liu, Yuan Cheng, Xiaodi Wang and Xuechong Ren
Metals 2025, 15(12), 1300; https://doi.org/10.3390/met15121300 - 26 Nov 2025
Abstract
Notch and size effects significantly influence the fatigue performance of engineering components, which is crucial for ensuring structural integrity. A novel probabilistic fatigue life prediction Kt-V-L model considering both the size and the notch effect, based on the theory of critical distance L
[...] Read more.
Notch and size effects significantly influence the fatigue performance of engineering components, which is crucial for ensuring structural integrity. A novel probabilistic fatigue life prediction Kt-V-L model considering both the size and the notch effect, based on the theory of critical distance L (TCD) and the improved highly stressed volume V (HSV) method, is proposed in this study. The new definition more accurately characterizes fatigue damage and accumulation, overcoming the underestimation issues of traditional HSV methods under high-stress or low cycle fatigue (LCF) conditions. Specifically, the Weibull distribution is also proposed to characterize the material fatigue failure probability. The experimental data of 26Cr2Ni4MoV, En3B, and TC4 materials with varying notched sizes are utilized for the model validation and comparison. In addition, the predictive ability of the point method (Kt-V-L-PM) and line method (Kt-V-L-LM) under the novel proposed model was explored and evaluated. The predicted lives of 26Cr2Ni4MoV specimens fall within the ±2 scatter band of the Kt-V-L-LM, while the Kt-V-L-PM shows increasing deviation with larger notches due to its limited ability to capture stress gradients. For En3B and TC4, the predicted lives are within ± 2 life factors, verifying the model’s reliability and accuracy. Furthermore, fracture morphology analysis reveals the influence of notches on fatigue performance and elucidates the fracture failure mechanisms.
Full article
(This article belongs to the Special Issue Fatigue, Fracture, and Multiaxial Integrity of Metallic Structure Materials: From Microstructure to Data-Driven Assessment)
►▼
Show Figures

Figure 1
Journal Menu
► ▼ Journal Menu-
- Metals Home
- Aims & Scope
- Editorial Board
- Reviewer Board
- Topical Advisory Panel
- Photography Exhibition
- Instructions for Authors
- Special Issues
- Topics
- Sections
- Article Processing Charge
- Indexing & Archiving
- Editor’s Choice Articles
- Most Cited & Viewed
- Journal Statistics
- Journal History
- Journal Awards
- Society Collaborations
- Conferences
- Editorial Office
Journal Browser
► ▼ Journal BrowserHighly Accessed Articles
Latest Books
E-Mail Alert
News
Topics
Topic in
Alloys, Materials, Metals
Development of Light Alloys with Excellent Mechanical Properties
Topic Editors: Zhirou Zhang, Isaac ChangDeadline: 31 December 2025
Topic in
JFB, Materials, Metals, Nanomanufacturing, Nanomaterials
Physical Methods for the Synthesis of Materials and Their Applications
Topic Editors: Vincenzo Amendola, Gregory GuisbiersDeadline: 31 March 2026
Topic in
Applied Sciences, Buildings, Construction Materials, CMD, Materials, Metals
Construction Materials: Corrosion, Prevention and Protection
Topic Editors: Sergio Lorenzi, Marco OrmelleseDeadline: 1 May 2026
Topic in
Analytica, Metals, Molecules, Processes, Separations
Advances in Solvent Extraction
Topic Editors: Guoquan Zhang, Weizao LiuDeadline: 31 May 2026
Conferences
Special Issues
Special Issue in
Metals
Selected Papers from the 2nd International Electronic Conference on Metals (IECME2025)
Guest Editors: Dongyang Li, Yung ShinDeadline: 30 November 2025
Special Issue in
Metals
Advances in the Manufacture and Performance of Nuclear Metallic Materials
Guest Editor: Kun YangDeadline: 30 November 2025
Special Issue in
Metals
Advances in Steels: Heat Treatment, Microstructure and Properties
Guest Editor: Zhenghua TangDeadline: 30 November 2025
Special Issue in
Metals
Crack Formation and Propagation in Metal Structures: Simulation, Analysis, and Experimental Investigation
Guest Editors: Carsten Koenke, Ahmed Al-MukhtarDeadline: 30 November 2025



