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Volume 14
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Metals, Volume 14, Issue 7 (July 2024) – 37 articles

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24 pages, 2163 KiB  
Article
Multi-Output Prediction Model for Basic Oxygen Furnace Steelmaking Based on the Fusion of Deep Convolution and Attention Mechanisms
by Qianqian Dong, Min Li, Shuaijie Hu, Yan Yu and Maoqiang Gu
Metals 2024, 14(7), 773; https://doi.org/10.3390/met14070773 (registering DOI) - 29 Jun 2024
Abstract
The objective of basic oxygen furnace (BOF) steelmaking is to achieve molten steel with final carbon content, temperature, and phosphorus content meeting the requirements. Accurate prediction of the above properties is crucial for end-point control in BOF steelmaking. Traditional prediction models typically use [...] Read more.
The objective of basic oxygen furnace (BOF) steelmaking is to achieve molten steel with final carbon content, temperature, and phosphorus content meeting the requirements. Accurate prediction of the above properties is crucial for end-point control in BOF steelmaking. Traditional prediction models typically use multi-variable input and single-variable output approaches, neglecting the coupling relationships between different property indicators, making it difficult to predict multiple outputs simultaneously. Consequently, a multi-output prediction model based on the fusion of deep convolution and attention mechanism networks (FDCAN) is proposed. The model inputs include scalar data, such as the properties of raw materials and target molten steel, and time series data, such as lance height, oxygen supply intensity, and bottom air supply intensity during the blowing process. The FDCAN model utilizes a fully connected module to extract nonlinear features from scalar data and a deep convolution module to process time series data, capturing high-dimensional feature representations. The attention mechanism then assigns greater weight to significant features. Finally, multiple multi-layer perceptron modules predict the outputs—final carbon content, temperature, and phosphorus content. This structure allows FDCAN to learn complex relationships within the input data and between input and output variables. The effectiveness of the FDCAN model is validated using actual BOF steelmaking data, achieving hit rates of 95.14% for final carbon content within ±0.015 wt%, 84.72% for final temperature within ±15 °C, and 88.89% for final phosphorus content within ±0.005 wt%. Full article
(This article belongs to the Special Issue Process and Numerical Simulation of Oxygen Steelmaking)
13 pages, 8238 KiB  
Article
Advancements in Hybrid Additive Manufacturing: Integrating SLM and LMD for High-Performance Applications
by Deviprasad Chalicheemalapalli Jayasankar, Stefan Gnaase, Maximilian Alexander Kaiser, Dennis Lehnert and Thomas Tröster
Metals 2024, 14(7), 772; https://doi.org/10.3390/met14070772 (registering DOI) - 29 Jun 2024
Abstract
Additive manufacturing (AM) technologies enable near-net-shape designs and demand-oriented material usage, which significantly minimizes waste. This points to a substantial opportunity for further optimization in material savings and process design. The current study delves into the advancement of sustainable manufacturing practices in the [...] Read more.
Additive manufacturing (AM) technologies enable near-net-shape designs and demand-oriented material usage, which significantly minimizes waste. This points to a substantial opportunity for further optimization in material savings and process design. The current study delves into the advancement of sustainable manufacturing practices in the automotive industry, emphasizing the crucial role of lightweight construction concepts and AM technologies in enhancing resource efficiency and reducing greenhouse gas emissions. By exploring the integration of novel AM techniques such as selective laser melting (SLM) and laser metal deposition (LMD), the study aims to overcome existing limitations like slow build-up rates and limited component resolution. The study’s core objective revolves around the development and validation of a continuous process chain that synergizes different AM routes. In the current study, the continuous process chain for DMG MORI Lasertec 65 3D’s LMD system and the DMG MORI Lasertec 30 3D’s was demonstrated using 316L and 1.2709 steel materials. This integrated approach is designed to significantly curtail process times and minimize component costs, thus suggesting an industry-oriented process chain for future manufacturing paradigms. Additionally, the research investigates the production and material behavior of components under varying manufacturing processes, material combinations, and boundary layer materials. The culmination of this study is the validation of the proposed process route through a technology demonstrator, assessing its scalability and setting a benchmark for resource-efficient manufacturing in the automotive sector. Full article
(This article belongs to the Special Issue Advances in Laser Metal Deposition Processes)
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14 pages, 12930 KiB  
Article
Surface Morphology and Formation of Nanocrystals in an Amorphous Zr55Cu30Al10Ni5 Alloy under High-Pressure Torsion
by Galina Abrosimova, Oleg Aksenov, Nikita Volkov, Danila Matveev, Elena Pershina and Alexandr Aronin
Metals 2024, 14(7), 771; https://doi.org/10.3390/met14070771 (registering DOI) - 29 Jun 2024
Abstract
A change in the structure of an amorphous Zr55Cu30Al10Ni5 alloy under deformation by high-pressure torsion (HPT) was studied by X-ray diffraction, high-resolution electron microscopy, scanning electron microscopy, and atomic force microscopy. It was found that the [...] Read more.
A change in the structure of an amorphous Zr55Cu30Al10Ni5 alloy under deformation by high-pressure torsion (HPT) was studied by X-ray diffraction, high-resolution electron microscopy, scanning electron microscopy, and atomic force microscopy. It was found that the uneven distribution of deformation along the radius of the sample, characteristic of deformation by high-pressure torsion, led to the formation of an inhomogeneous structure. The formation of nanocrystals begins at the periphery of the sample. The threshold value of deformation required for crystallization onset was established; the formation of nanocrystals begins in areas with true deformation e = 4.83 or more. An increase in the deformation degree led to an increase in the height of steps on the deformed sample surface and an increase in the roughness of the surface. The thickness of an elementary step that was formed when one shear band came out to the surface was 10 nm, and its height was about 1 nm. It was found that large steps on the deformed surface of the sample had a complex structure and consisted of a large number of elementary steps. The results obtained are important for analyzing the stress distribution and the concentration of free volume in a deformed material, which affect the parameters of the amorphous-nanocrystalline structure formed. Full article
(This article belongs to the Section Metallic Functional Materials)
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20 pages, 2031 KiB  
Article
Experimental Studies on the Anisotropic Fatigue Behaviour of IN718 Fabricated via Wire Arc Additive Manufacturing
by Guiyi Wu, Maohong Yang, Zhaohui Yu, Shuyan Zhang, Hongbo Liu and Jun Xiong
Metals 2024, 14(7), 770; https://doi.org/10.3390/met14070770 (registering DOI) - 28 Jun 2024
Viewed by 34
Abstract
Wire and arc additive manufacturing (WAAM) offers promise in creating large complex structures due to its flexibility and high material deposition rates. The nickel-based alloy IN718 is favoured for WAAM due to its weldability and compatibility. However, WAAM can introduce issues like anisotropic [...] Read more.
Wire and arc additive manufacturing (WAAM) offers promise in creating large complex structures due to its flexibility and high material deposition rates. The nickel-based alloy IN718 is favoured for WAAM due to its weldability and compatibility. However, WAAM can introduce issues like anisotropic grain structure, porosity, and residual stresses which can lead to directional variations in tensile, fatigue, and fracture behaviour. This paper studied the WAAM process of IN718, utilising cold metal transfer (CMT). The optimised CMT-WAAM parameters for IN718 were identified to as a wire feed speed of 8–10 m/min and a torch travel speed of 0.5–0.7 m/min, resulting in stable deposition and minimal defects. Nevertheless, columnar grain structures were observed in the build direction (BD), with coarse grains in the wall-length direction (WD). This anisotropic microstructure coupled with stress concentrators, contributes to the directional dependence observed in tensile properties, fatigue endurance, and crack growth. The investigation revealed superior ductility in the BD compared to the WD. Interestingly, the fatigue endurance testing showed a longer life in the WD compared with the BD, attributed to stronger stress concentrators in the BD specimens. However, when examining a cracked specimen, the fatigue crack propagated faster in the WD rather than the BD. Full article
21 pages, 4262 KiB  
Article
Quantitative Microstructure Prediction of Powder High-Temperature Alloy during Solution Heat Treatment and Its Validation
by Zhaofeng Liu, Junyi Cheng, Chao Wang and Jianzheng Guo
Metals 2024, 14(7), 769; https://doi.org/10.3390/met14070769 (registering DOI) - 28 Jun 2024
Viewed by 64
Abstract
Heat treatment, particularly solution heat treatment, is a critical process in the preparation of powder metallurgy superalloys, where the cooling process significantly impacts the microstructure. This study, based on thermodynamic and kinetic databases as well as the precipitation mechanism of strengthening phases, delves [...] Read more.
Heat treatment, particularly solution heat treatment, is a critical process in the preparation of powder metallurgy superalloys, where the cooling process significantly impacts the microstructure. This study, based on thermodynamic and kinetic databases as well as the precipitation mechanism of strengthening phases, delves into the influence of cooling process, especially the cooling path, on the material’s microstructure. The results indicate that under slow cooling rates, the precipitated phases are more likely to exhibit a multimodal size distribution, while under rapid cooling rates, a unimodal distribution may form. The average cooling rate does not consistently accurately reflect the growth of the precipitated phases; even with the same average cooling rate, different cooling paths can lead to significant differences in the size of the precipitates. To accurately predict the size of the precipitates, it is necessary to consider the specific cooling process. Constant cooling rate experiments designed for the study and the dissection testing of full-size turbine discs produced in manufacturing validated the calculated results of the precipitates. Therefore, optimizing cooling through simulation calculations can effectively and accurately control the precipitates, thereby obtaining a microstructure that can meet performance requirements. Full article
(This article belongs to the Section Powder Metallurgy)
26 pages, 1615 KiB  
Article
Improving the Corrosion Resistance of Anodized Al 1050 Alloy by Sealing in Cerium-Containing and Mixed Sodium Phosphate Mono Basic and Calcium Nitrate Solutions
by Reni Andreeva, Aleksandar Tsanev and Dimitar Stoychev
Metals 2024, 14(7), 768; https://doi.org/10.3390/met14070768 (registering DOI) - 28 Jun 2024
Viewed by 68
Abstract
This investigation presents results on the improvement of the corrosion-protective effect of consecutive sealing treatments of anodized Al 1050 (AlAnod). The treatments were performed in cerium-containing and mixed NaH2PO4 + Ca(NO3)2 solutions. The changes of [...] Read more.
This investigation presents results on the improvement of the corrosion-protective effect of consecutive sealing treatments of anodized Al 1050 (AlAnod). The treatments were performed in cerium-containing and mixed NaH2PO4 + Ca(NO3)2 solutions. The changes of the surface morphology, structure and chemical composition, chemical state of the elements, and basic corrosion parameters of the studied systems were investigated by SEM, EDXS, XRD, XPS, and a complex of electrochemical techniques (PDP, EOCP vs. timeplot, chronoamperometric transients, Rp and CR at ЕOCP, etc.). The results obtained show that the basic components of the obtained sealing conversion layers (before and after exposure to model Cl−-containing corrosion media) are characterized by Ca10(PO4)6(OH)2, AlO(OH), CePO4, and CeAlO3 (after the corrosion tests, they are converted to insoluble Me-PO3 and Me-P4O10). We conclude that the observed decrease in the corrosion rate of Al and the corresponding increase in the polarization resistance are accomplished by the two-step sealing treatment, which fills up the AlAnod pores with insoluble deposits. Full article
(This article belongs to the Special Issue Editorial Board Members’ Collection Series: "Corrosion Protection and Prevention")
13 pages, 2260 KiB  
Article
Optimization of Clinching Joint Process with Preforming between Ultra-High-Strength Steel and Aluminum Alloy Sheets
by Lun Fu, Shanyin Zhang, Ping Qiu, Hong Xiao, Boran Deng and Xiaoxin Lu
Metals 2024, 14(7), 767; https://doi.org/10.3390/met14070767 (registering DOI) - 28 Jun 2024
Viewed by 86
Abstract
With the rapid development of lightweight automobiles, the clinching joint technology of ultra-high-strength steel with aluminum alloy sheets have been paid more and more attention. However, due to significant differences in plastic deformation capabilities between the two metals, particularly the difficulty of steel [...] Read more.
With the rapid development of lightweight automobiles, the clinching joint technology of ultra-high-strength steel with aluminum alloy sheets have been paid more and more attention. However, due to significant differences in plastic deformation capabilities between the two metals, particularly the difficulty of steel sheet deformation, conventional clinching processes often result in insufficient joint interlocking or fracture issues. Although the preliminary use of clinching processes with preforming methods has shown some effectiveness in connecting two types of sheets, the bond strength is not high. This study employs finite element simulation and orthogonal optimization methods to investigate the impact of relevant process parameters on joint morphology in clinching processes with preforming. Under the condition of optimizing process parameters, a clinching punch with an added pressure-step structure was proposed to compact the joint and further enhance joint quality. Experimental verification demonstrates the feasibility of the improved clinching processes with preforming for bonding ultra-high-strength steel and aluminum alloy sheets. Full article
(This article belongs to the Special Issue Metal Plastic Deformation and Forming)
14 pages, 12015 KiB  
Communication
Microstructure Evolution of Alloy 800H during Cold Rolling and Subsequent Annealing
by Qingshan Dong, Qiang Wang and Fei Long
Metals 2024, 14(7), 766; https://doi.org/10.3390/met14070766 - 28 Jun 2024
Viewed by 116
Abstract
The microstructure evolution during the cold rolling and subsequent annealing of Alloy 800H was investigated. Two distinct rolling methods, unidirectional rolling and cross-rolling, were introduced. Cracks were observed in the cross-rolled plates, while such cracks did not appear in the unidirectionally rolled plates, [...] Read more.
The microstructure evolution during the cold rolling and subsequent annealing of Alloy 800H was investigated. Two distinct rolling methods, unidirectional rolling and cross-rolling, were introduced. Cracks were observed in the cross-rolled plates, while such cracks did not appear in the unidirectionally rolled plates, which indicated better ductility during the unidirectional rolling process. The difference between the two different rolling methods was explained by the evolution of Schmit factors during the deformation. A higher volume fraction of large, deformed grains was observed in the cross-rolled plates than in the unidirectionally rolled plates. Abnormal grain growth was observed in the cross-rolled specimens after annealing while no abnormal grain growth was seen in the unidirectionally rolled ones. In addition, the recrystallization occurred faster in plates from unidirectional rolling than from cross-rolling. Full article
(This article belongs to the Special Issue Advances in Field-Assisted Processing of Metallic Materials: Experiments and Simulations)
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12 pages, 2551 KiB  
Article
Obtaining Heterogeneous Microstructure and Enhanced Mechanical Properties in ECAP-Processed AZ61 Alloys via Single-Pass Rolling with Increased Rolling Reduction
by Qiong Xu, Yuhua Li, Aibin Ma, Jinghua Jiang and Donghui Yang
Metals 2024, 14(7), 765; https://doi.org/10.3390/met14070765 - 27 Jun 2024
Viewed by 154
Abstract
Material design and preparation based on constructing heterogeneous microstructures can break the conventional performance limitations of fine-grained magnesium alloys. In this study, AZ61 alloys processed via multi-pass equal channel angular pressing (ECAP) were subjected to single-pass rolling (SPR) with increased rolling reductions. The [...] Read more.
Material design and preparation based on constructing heterogeneous microstructures can break the conventional performance limitations of fine-grained magnesium alloys. In this study, AZ61 alloys processed via multi-pass equal channel angular pressing (ECAP) were subjected to single-pass rolling (SPR) with increased rolling reductions. The effect of rolling reduction on the formation of heterogeneous microstructure and the mechanical properties of the alloy was investigated. Microstructural examinations revealed that a heterogeneous microstructure was formed in the alloy at varied rolling reductions, but the desired heterostructure with higher fine grain contents could only be achieved at increased rolling reduction. This was mainly due to the fact that the alloy underwent partial dynamic recrystallization (PDRX) under SPR, and PDRX more easily occurred with higher rolling reduction. The tensile test results showed that with increased rolling reduction, the strength of the alloy first increased and then decreased slightly, with the ductility steadily increasing. Improved mechanical properties were achieved in the alloy rolled at increased rolling reductions owing to the heterogeneous microstructure with a greater content of fine grains. Full article
(This article belongs to the Special Issue Microstructure Evolution and Mechanical Properties of Magnesium Alloys—2nd Edition)
20 pages, 5096 KiB  
Article
Corrosion Behavior and Mechanical Properties of Zn–Ti Alloys as Biodegradable Materials
by Alexandra-Tamara Șutic, Romeu Chelariu, Ramona Cimpoeșu, Ana-Maria Roman, Bogdan Istrate, Viorel Goanță, Marcelin Benchea, Mihaela Moscu, Adrian Alexandru, Nicanor Cimpoeşu and Georgeta Zegan
Metals 2024, 14(7), 764; https://doi.org/10.3390/met14070764 - 27 Jun 2024
Viewed by 140
Abstract
The influence of the chemical composition and structural state of Zn–Ti alloys on corrosion behaviour and mechanical properties was studied. Zn-based alloys were investigated, more precisely, pure technical Zn and Zn with 0.10, 0.25 and 1.00 wt.% Ti. The microstructure and chemical composition [...] Read more.
The influence of the chemical composition and structural state of Zn–Ti alloys on corrosion behaviour and mechanical properties was studied. Zn-based alloys were investigated, more precisely, pure technical Zn and Zn with 0.10, 0.25 and 1.00 wt.% Ti. The microstructure and chemical composition of these materials were analysed using light optical microscopy (LOM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The chemical composition of the alloys and the surface after immersion were analysed using an EDS detector from Bruker. The alloys’ electro-chemical corrosion resistance was further investigated through linear (LP) and cyclic (CP) potentiometry and open-circuit potential (OCP) analysis. A tensile/compression equipment (Instron 34SC-5) was used to determine the compression behaviour. UMT testing equipment was used to determine microhardness (by Rockwell indentation) and COF vs. length. For percentages higher than 0.25 wt.% Ti, the formation of a primary TiZn16 intermetallic compound in the (α-Zn + TiZn16) eutectic matrix was observed, a slight influence of TiZn16 on the Zn corrosion resistance results, and a greater influence on the mechanical properties was confirmed. Full article
(This article belongs to the Special Issue Feature Papers in Biobased and Biodegradable Metals)
14 pages, 1296 KiB  
Article
Quantitative Study on Hydrogen Concentration–Hydrogen Embrittlement Sensitivity of X80 Pipeline Steel Based on Hydrogen Permeation Kinetics
by Rundong Zhang, Songyuan Ai, Mujun Long, Lihua Wan, Yifan Li, Danbin Jia, Huamei Duan and Dengfu Chen
Metals 2024, 14(7), 763; https://doi.org/10.3390/met14070763 - 27 Jun 2024
Viewed by 170
Abstract
The hydrogen concentration in steel is directly related to the hydrogen embrittlement (HE) sensitivity of the steel. This study combined electrochemical hydrogen charging, the slow strain rate test (SSRT), and hydrogen permeation experiments to investigate the variation in the hydrogen concentration in pipeline [...] Read more.
The hydrogen concentration in steel is directly related to the hydrogen embrittlement (HE) sensitivity of the steel. This study combined electrochemical hydrogen charging, the slow strain rate test (SSRT), and hydrogen permeation experiments to investigate the variation in the hydrogen concentration in pipeline steel with the electrochemical hydrogen-charging time. The influence of the hydrogen concentration in steel on the mechanical properties of X80 pipeline steel was obtained, and ultimately, a quantitative relationship between the hydrogen concentration in steel and the hydrogen embrittlement sensitivity was established. The results show that the hydrogen concentration in the steel gradually increased with the time of hydrogen charging, and the quantitative relationship formula can be given as CH = 5.35 − 4.2 exp (−0.26t); the HE index of X80 steel increased with the hydrogen concentration. Additionally, once the hydrogen concentration in steel reaches 5.08 × 10−6 mol/cm3, even the slightest alteration in the hydrogen content will precipitate a dramatic decrease in plasticity. The quantitative relationship formula between the hydrogen concentration and the HE index (FH) in X80 steel can be given as FH = 0.029 exp (1.5CH) – 0.029. When the hydrogen concentration in steel is at a maximum, the FH of X80 steel reaches 88.6%. This study provides a reference for analyzing the quantitative relationship between the hydrogen concentration and the HE index in steel after electrochemical hydrogen charging. Full article
(This article belongs to the Special Issue State-of-Art: Metals Failure Analysis)
20 pages, 3953 KiB  
Article
Numerical Simulation of Burst Failure in 2.5-Inch Unbonded Flexible Riser Pressure Armor Layers
by Xiaoya Liu, Zhongyuan Qu, Yi Liu, Jiawei He, Guangju Si, Sicong Wang and Qingsheng Liu
Metals 2024, 14(7), 762; https://doi.org/10.3390/met14070762 - 27 Jun 2024
Viewed by 146
Abstract
Unbonded flexible risers have been widely used in the field of offshore engineering in recent years due to their excellent performance in extreme dynamic marine environments, structural compliance, low installation cost, and low quality. And, the internal pressure capacity of unbonded flexible risers [...] Read more.
Unbonded flexible risers have been widely used in the field of offshore engineering in recent years due to their excellent performance in extreme dynamic marine environments, structural compliance, low installation cost, and low quality. And, the internal pressure capacity of unbonded flexible risers is an important indicator of the mechanical performance of unbonded flexible risers. Based on a 2.5-inch, 8-layer typical unbonded flexible riser model, this paper examines the burst failure of the pressure armor layer. Firstly, the balance equation of each separate cylindrical layer and helical layer is derived by functional principle, and then the overall theoretical modeling of an unbonded flexible riser under axisymmetric loads is established by additionally considering the geometric relation between adjacent layers. Secondly, fully considering the complex cross-sectional geometric characteristics and the interlayer’s contact with the unbonded flexible riser, a simplified numerical 7-layer model is established by Abaqus, and the material with elastic-plastic properties is conferred. Finally, the validity of the proposed theoretical and numerical methods is verified through the axisymmetric behavior of the test data. Then the burst failure of the pressure armor layer is analyzed based on the material. At an internal pressure of 42 MPa, the pressure armor layer reached its yield stress of 300 MPa, with the entire cross-section yielding between 42 MPa and 42.5 MPa. Additionally, the effect of the friction coefficient is examined. Full article
(This article belongs to the Special Issue Mechanical Failure and Metal Degradation of Ships and Marine Structures (Volume II))
16 pages, 7591 KiB  
Article
Microstructure Image Segmentation of 23crni3mo Steel Carburized Layer Based on a Deep Neural Network
by BoXiang Gong and ZhenLong Zhu
Metals 2024, 14(7), 761; https://doi.org/10.3390/met14070761 - 27 Jun 2024
Viewed by 107
Abstract
This paper identifies and analyzes the microstructure of a carburized layer by using a deep convolutional neural network, selecting different carburizing processes to conduct surface treatment on 23CrNi3Mo steel, collecting many metallographic pictures of the carburized layer based on laser confocal microscopy, and [...] Read more.
This paper identifies and analyzes the microstructure of a carburized layer by using a deep convolutional neural network, selecting different carburizing processes to conduct surface treatment on 23CrNi3Mo steel, collecting many metallographic pictures of the carburized layer based on laser confocal microscopy, and building a microstructure dataset (MCLD) database for training and testing. Five algorithms—a full convolutional network (FCN), U-Net, DeepLabv3+, pyramid scene parsing network (PSPNet), and image cascade network (ICNet)—are used to segment the self-built microstructural dataset (MCLD). By comparing the five deep learning algorithms, a neural network model suitable for the MCLD database is identified and optimized. The research results achieve recognition, segmentation, and statistic verification of metallographic microstructure images through a deep convolutional neural network. This approach can replace the high cost and complicated process of experimental testing of retained austenite and martensite. This new method is provided to identify and calculate the content of residual austenite and martensite in the carburized layer of low-carbon steel, which lays a theoretical foundation for optimizing the carburizing process. Full article
11 pages, 14189 KiB  
Article
Analysis of the Oxidation Behavior and Formation of an Extremely Thin Oxide Layer with a Novel Hot-Stamped Steel
by Yan Zhao, Lei Liu, Dengcui Yang, Weinan Li, Jianlin Yu and Zhengzhi Zhao
Metals 2024, 14(7), 760; https://doi.org/10.3390/met14070760 - 27 Jun 2024
Viewed by 136
Abstract
This study investigates enhancing the high-temperature oxidation resistance of hot-stamped steels by adding the Cr/Mn/Si elements to form an extremely thin oxide layer. Under low oxygen partial pressure conditions and high Cr content in the matrix, the oxide layer of a 38Cr3MnNbVMo hot-rolled [...] Read more.
This study investigates enhancing the high-temperature oxidation resistance of hot-stamped steels by adding the Cr/Mn/Si elements to form an extremely thin oxide layer. Under low oxygen partial pressure conditions and high Cr content in the matrix, the oxide layer of a 38Cr3MnNbVMo hot-rolled plate containing the Mo element and high Si content was further thinned to 0.6 μm after cooling at 900 °C for 5 min. The structure of the ultra-thin oxide layer consists of Fe3O4, Mn oxides, FeCr2O4, Cr2O3, and Fe2SiO4 oxides. Compared to other antioxidant elements, under low oxygen partial pressure conditions, Si is more prone to oxidation, forming ultra-thin (22 nm) Fe2SiO4 oxides at the matrix interface. Combined with Cr2O3, FeCr2O4, and Mn oxides, it collectively inhibits the mutual diffusion of external O ions and matrix Fe ions. Furthermore, the addition of the Mo element improves the oxidation resistance. The synergistic effect of multiple powerful oxidation-resistant elements and oxide products effectively inhibits the growth of the iron oxide scale, enhancing the oxidation resistance of hot-rolled, hot-stamped steel. Full article
(This article belongs to the Special Issue Modeling Thermodynamic Systems and Optimizing Metallurgical Processes)
26 pages, 1624 KiB  
Article
The Effect of Energy Parameters of Power Sources on the Structure and Properties of Permanent Joints at Manual Arc Welding
by Dmitry P. Il’yashchenko, Dmitry A. Chinakhov and Elena V. Lavrova
Metals 2024, 14(7), 759; https://doi.org/10.3390/met14070759 - 27 Jun 2024
Viewed by 108
Abstract
The study presents the results of the research into the effect of the dynamic properties of inverter and diode power sources of welding arc power supply on the stability of melting and transfer of electrode metal into the weld pool. The principal energy [...] Read more.
The study presents the results of the research into the effect of the dynamic properties of inverter and diode power sources of welding arc power supply on the stability of melting and transfer of electrode metal into the weld pool. The principal energy parameters of the power source include the rates of rise and fall of short-circuit current, the ratio of arc burning current to short-circuit current, and other related factors. It has been demonstrated that an increase in the rate of change of these parameters within one welding mode microcycle alters the properties of heat and mass transfer, increases the frequency of electrode metal droplet transfer, reduces the size of transferred droplets in the weld pool and the duration of their stay on the electrode end under the influence of the high temperature of the welding arc, and the duration of short circuits. The increase in the mass fraction of alloying elements at their transition from the coated electrode to the weld metal is demonstrated to depend on the rate of change of the main energy parameters of one welding mode microcycle of the inverter power source in comparison with the diode rectifier. An enhancement in the structural integrity and properties of permanent joints during welding has been observed when using an inverter power source for the welding arc with high dynamic properties. Full article
(This article belongs to the Special Issue Advanced Welding Technology in Metals III)
15 pages, 14517 KiB  
Article
Effect of Tool Speed on Microstructure Evolution and Mechanical Properties of Friction Stir Welded Joints of Al-Mg-Si Alloy with High Cu Content
by Wangzhen Li, Zhang Luo, Youping Sun and Xinyu Liu
Metals 2024, 14(7), 758; https://doi.org/10.3390/met14070758 - 27 Jun 2024
Viewed by 158
Abstract
OM, SEM, EBSD, and other analytical techniques were utilized to investigate the effects of the rotating speed of a mixing head on the microstructures and mechanical properties of a joint. The results indicate that, compared with the base material, the grain size in [...] Read more.
OM, SEM, EBSD, and other analytical techniques were utilized to investigate the effects of the rotating speed of a mixing head on the microstructures and mechanical properties of a joint. The results indicate that, compared with the base material, the grain size in the nugget zone is significantly refined. Furthermore, as the rotational speed of the mixing head increases, the grain size in the nugget zone increases noticeably, and the proportion of high-angle grain boundary length initially decreases and then increases. The texture types in different areas of the joint are markedly distinct: the base material primarily consists of recrystallization texture and rolling texture, while the core zone mainly comprises C-shear texture. Among the joints tested at various rotation speeds, the lowest hardness values are observed in the advancing side heat-affected zone, and the tensile properties of the joints are notably reduced due to the dissolution and coarsening of the second phase. The joint exhibits optimal performance at 1000 r/min, with a tensile strength and elongation of 196.3 MPa and 13.5%, respectively. Full article
(This article belongs to the Special Issue Simulation and Optimization Methods in Machining and Structure/Material Design)
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14 pages, 797 KiB  
Article
Effects of the Substitution of B and C for P on Magnetic Properties of FePCB Amorphous Alloys
by Shuwei Lu, Xuan Chen and Qiqi Zheng
Metals 2024, 14(7), 757; https://doi.org/10.3390/met14070757 - 26 Jun 2024
Viewed by 189
Abstract
In the present study, first-principles molecular dynamics simulations were employed to study the effects of small amounts of B and C substituted for P on the structure and magnetic properties of Fe80P13C7, Fe80P10C [...] Read more.
In the present study, first-principles molecular dynamics simulations were employed to study the effects of small amounts of B and C substituted for P on the structure and magnetic properties of Fe80P13C7, Fe80P10C7B3, and Fe80P8C9B3 amorphous alloys. A small amount of B and C replacing P atoms increases the icosahedral structure of the amorphous alloys, especially the increase in the regular icosahedral structure. The saturation magnetization of the three kinds of amorphous alloys gradually increases with the addition of B and C atoms, and the results of experimental and simulated calculations show consistent trends. The substitution of P atoms by B and C atoms leads to the aggregation of Fe atoms, which increases the magnetic moment of the iron atoms. In addition, the improvement of local structural symmetry may be one of the reasons for the increase in saturation magnetization of amorphous alloys. The substitution of a small number of B and C atoms plays an important role in improving the saturation magnetization of the amorphous alloy, which has a certain guiding significance for the development of amorphous alloys with excellent soft magnetic properties. Full article
11 pages, 1707 KiB  
Article
A New Wear Calculation Method for Galvanized Ultra-High-Strength Steel during Hot Stamping
by Yuchun Peng, Wei Chen and Hongming Zhou
Metals 2024, 14(7), 756; https://doi.org/10.3390/met14070756 - 26 Jun 2024
Viewed by 161
Abstract
In the hot stamping process, the friction and wear interaction between the high-temperature sheet metal and the water-cooled die has a significant impact on the final quality of the product and the durability of the die. Currently, most research on the wear of [...] Read more.
In the hot stamping process, the friction and wear interaction between the high-temperature sheet metal and the water-cooled die has a significant impact on the final quality of the product and the durability of the die. Currently, most research on the wear of the stamped parts during the hot stamping process mainly involves analyzing the wear morphology and wear mechanism of the sheet surface, and there is little research on its wear assessment. In this study, to better assess the forming quality of hot stamping parts, the research takes the direct hot stamping of galvanized ultra-high-strength steel sheets as the object and proposes a wear amount calculation method of galvanized ultra-high-strength steel sheets based on the real contact area of the high-temperature sheet metal and the water-cooled tools. At different temperature conditions, the galvanized layer and steel substrate have different mechanical properties. The model is validated using the sheet characteristics at 650 °C, 700 °C, and 750 °C. The results indicate that the model can predict the wear of the galvanized steel sheet under different conditions within a certain range. Full article
(This article belongs to the Special Issue Metal Composite Materials and Their Interface Behavior)
16 pages, 1733 KiB  
Article
Dry, Cold Forging of Oxygen-Free Copper by Massively Nitrogen-Supersaturated CoCrMo Dies
by Tatsuhiko Aizawa, Tatsuya Funazuka and Tomomi Shiratori
Metals 2024, 14(7), 755; https://doi.org/10.3390/met14070755 - 26 Jun 2024
Viewed by 150
Abstract
With the aim of achieving a sustainable society with green manufacturing, every metal-forming process has been changed to a dry process with the use of limited lubricants via regulation. In parallel, die materials must have sufficient wear resistance to prolong the die life [...] Read more.
With the aim of achieving a sustainable society with green manufacturing, every metal-forming process has been changed to a dry process with the use of limited lubricants via regulation. In parallel, die materials must have sufficient wear resistance to prolong the die life even when forming active metals. A massively nitrogen-supersaturated (MNSed) superalloy was selected as a galling-free die substrate to forge oxygen-free copper wires and bars in dry conditions. A plasma immersion nitriding system was utilized to induce nitrogen supersaturation in CoCrMo, forging dies at 723 K for 21.6 ks with a high nitrogen solute content. Microstructure analyses and microhardness testing proved that the MNSed CoCrMo die had a multilayered structure from the top surface to the depth and that the surface hardness increased up to 1300 HV. Dry, cold forging experiments demonstrated that the oxygen-free copper bar was upset, with a reduction in thickness of 70% in a single stroke under low friction. No fresh copper work debris adhered onto the MNSed CoCrMo die surface. The loading–stroke relationship was used to describe the forging behavior, with low friction and without galling. Full article
(This article belongs to the Special Issue Advances in Metal Rolling Processes)
14 pages, 6830 KiB  
Article
Layer Approach to Model Fatigue Strength of Surface-Hardened Components
by Dénes Dobberke, Martin Leitner, Jens Wiebesiek and Jürgen Fröschl
Metals 2024, 14(7), 754; https://doi.org/10.3390/met14070754 - 25 Jun 2024
Viewed by 448
Abstract
This paper deals with a surface-hardened forged steel that is commonly used for powertrain components like gears, axles or crankshafts. In order to increase static and fatigue strength and to minimise wear, surface treatments like induction hardening lead to a significant microstructural change [...] Read more.
This paper deals with a surface-hardened forged steel that is commonly used for powertrain components like gears, axles or crankshafts. In order to increase static and fatigue strength and to minimise wear, surface treatments like induction hardening lead to a significant microstructural change within heat-affected zones. The aim of this study was to elaborate a method for a reliable computational estimation of the local fatigue strength by considering local material properties. The method is based on experimental test results, where specimens were extracted from forged crankshafts and further heat-treated to investigate the fatigue strength of the unhardened and hardened material condition. The experimental test data were fundamental in defining elaborated Haigh diagrams, enabling a more reliable local fatigue assessment. The comparison of the component safety within the fatigue strength verification for a crankshaft section under alternate bending resulted in 28%-more progressive dimensioning of surface hardened layers. Full article
(This article belongs to the Special Issue Fatigue, Fracture and Damage of Steels)
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17 pages, 5601 KiB  
Article
The Influence of Insertion Depth of Inorganic Materials on Solidification Microstructure and Segregation of 2.5-ton 42CrMo Ingot
by Shujian Sun, Yonglong Du, Zhenqiang Zhang, Danqing Jiang, Songzhe Xu and Zhongming Ren
Metals 2024, 14(7), 753; https://doi.org/10.3390/met14070753 - 25 Jun 2024
Viewed by 354
Abstract
In this work, a novel internal heat absorption technology using inorganic material rods is employed during the solidification process of steel ingots, aiming to control their solidification and improve the quality of the final product. The study investigates the effect of the insertion [...] Read more.
In this work, a novel internal heat absorption technology using inorganic material rods is employed during the solidification process of steel ingots, aiming to control their solidification and improve the quality of the final product. The study investigates the effect of the insertion depth of inorganic materials on the solidification microstructure and macrosegregation of 2.5-ton 42CrMo ingots. The mechanical properties of samples from the product are also tested. A numerical simulation model for casting 2.5-ton ingots is established and implemented in Ansys Fluent fluid simulation software, with inorganic material rods set at different preset depths. The simulation explores the physical processes of the melting and floating of inorganic materials in molten steel, as well as their effects on the temperature and flow fields of the material. The results show that deeper insertion of inorganic materials (200 mm from the hot top) reduces the tendency for macrosegregation compared to that at the insertion depth of 100 mm. Specifically, the positive segregation area decreases by 10.35%, while the negative segregation area decreases by 15.32%. Moreover, deeper insertion results in a significant refinement of the solidification microstructure, ultimately enhancing the mechanical properties of the products machined from the ingots (i.e., the yield strength increased by 4.7%). The numerical simulation results indicate that as the placement depth of inorganic materials in the ingot mold increases, the cooling effect becomes more significant, the flow area of molten steel initiated by the inorganic materials expands, and the linear velocity of the double-circle flow increases. This further explains why the solidification quality of the ingots improves with the increasing placement depth of inorganic materials. Full article
14 pages, 1638 KiB  
Article
Study of Phase Transformations and Interface Evolution in Carbon Steel under Temperatures and Loads Using Molecular Dynamics Simulation
by Chao Wen, Zhengminqing Li, Hongyan Wu and Jianfeng Gu
Metals 2024, 14(7), 752; https://doi.org/10.3390/met14070752 - 25 Jun 2024
Viewed by 350
Abstract
Carbon steel materials are widely used in mechanical transmission. Under different temperature and pressure service conditions, the microscopic changes of stress and strain that are difficult to detect and analyze by experimental means will lead to failure deformation, thus affecting their operational stability [...] Read more.
Carbon steel materials are widely used in mechanical transmission. Under different temperature and pressure service conditions, the microscopic changes of stress and strain that are difficult to detect and analyze by experimental means will lead to failure deformation, thus affecting their operational stability and life. In this study, the molecular dynamics method is used to simulate the heating–cooling phase transition process of common carbon steel materials. Austenite transformation temperatures of 980 K (0.2 wt.%) and 1095 K (0.5 wt.%) are acquired which is determined by the volume hysteresis before and after transformation, which is consistent with the results of JMatPro phase diagram analysis. The internal stress state of the material varies between compressive stress and tensile stress due to the change of phase structure, and the dislocation characteristics during the phase transition period are observed to change significantly. Then, an α/γ two-phase interface model is constructed to study the migration of the phase interface and the change of the phase structure by applying a continuously changing external load. At the same time, the transition pressure of α→ϵ is obtained with a value of 37 GPa under three different initial loads showing the independence of the initial load and the historical path. Based on the molecular dynamics simulation and the phase diagram calculation of the carbon steel, the analysis method for the microstructure transformation and the stress–strain behavior of the phase interface under the external load can provide a reference for the design of microstructure and mechanical properties of alloy steel in the future. Full article
11 pages, 2172 KiB  
Article
Effect of Electric Pulse Treatment on Microstructure and Mechanical Property of Laser Powder Bed Fused IN718
by Hongmei Zhang, Jie Liu and Zhanfeng Wang
Metals 2024, 14(7), 751; https://doi.org/10.3390/met14070751 - 25 Jun 2024
Viewed by 338
Abstract
This study investigated the impact of electric pulse treatment (EPT) on the microstructure and mechanical properties of laser powder bed fused Inconel 718 (IN718). Through a comprehensive experimental characterization, we found that EPT induced significant improvements in the microstructure of IN718. In the [...] Read more.
This study investigated the impact of electric pulse treatment (EPT) on the microstructure and mechanical properties of laser powder bed fused Inconel 718 (IN718). Through a comprehensive experimental characterization, we found that EPT induced significant improvements in the microstructure of IN718. In the YOZ plane of EPT-700, the molten pool diminished and replaced by a grain boundary with granular Ni3Nb precipitates, and the dislocations increased while the irregular porosity decreased. Concurrently, enhanced mechanical properties of EPT-700 were obtained, including a hardness of 354.7 HV, an ultimate tensile strength of 930.21 MPa, and an elongation of 34.35%. Fractographic analysis revealed a transition in fracture mechanisms, highlighting the intricate relationship between microstructural modifications induced by EPT and mechanical response under load. These findings underscore the potential of EPT as a promising post-processing technique for optimizing the microstructure and mechanical properties of IN718 components fabricated via laser powder bed fusion additive manufacturing. This study contributes to the advancement of knowledge in the field of additive manufacturing and provides valuable insights for the development of high-performance metallic components. Full article
(This article belongs to the Section Additive Manufacturing)
12 pages, 777 KiB  
Article
On the Efficiency of Air-Cooled Metal Foam Heat Exchangers
by Thomas Fiedler, Nima Movahedi and Rohan Stanger
Metals 2024, 14(7), 750; https://doi.org/10.3390/met14070750 - 25 Jun 2024
Viewed by 296
Abstract
This study analyses the heat transfer performance of metal foam heat exchangers through experimental measurements. Using counter-gravity infiltration casting, open-cell aluminium foam elements were manufactured to embed a copper tube for internal mass flow containment. Heat transfer experiments were conducted under natural and [...] Read more.
This study analyses the heat transfer performance of metal foam heat exchangers through experimental measurements. Using counter-gravity infiltration casting, open-cell aluminium foam elements were manufactured to embed a copper tube for internal mass flow containment. Heat transfer experiments were conducted under natural and forced convection conditions, with the airflow controlled in a wind tunnel. A stream of warm water within the internal foam component served as the heat source, transferring thermal energy to the surrounding air flowing through the external foam component of the heat exchanger. The results showed a significantly enhanced heat transfer performance with aluminium foam compared to a single copper tube. Thermal resistance models were developed to elucidate the heat transfer mechanisms, highlighting the effectiveness of air-cooled metal foam heat exchangers. These findings underscore the potential of metal foam heat exchangers as cost-effective alternatives for various thermal management applications. Full article
(This article belongs to the Topic Modern Material Technologies Intended for Industrial Applications)
17 pages, 7038 KiB  
Article
Temperature-Dependent Mechanical Behaviors and Deformation Mechanisms in a Si-Added Medium-Entropy Superalloy with L12 Precipitation
by Tuanwei Zhang, Tianxiang Bai, Renlong Xiong, Shunhui Luo, Hui Chang, Shiyu Du, Jinyao Ma, Zhiming Jiao, Shengguo Ma, Jianjun Wang and Zhihua Wang
Metals 2024, 14(7), 749; https://doi.org/10.3390/met14070749 - 25 Jun 2024
Viewed by 334
Abstract
A novel Ni-Co-Cr-based medium-entropy superalloy with a high Si content (7.5 at%) strengthened by an L12 phase was developed. The pure L12 phase, characterized by an average size of 50 nm and a volume fraction of 46%, was precipitated within the [...] Read more.
A novel Ni-Co-Cr-based medium-entropy superalloy with a high Si content (7.5 at%) strengthened by an L12 phase was developed. The pure L12 phase, characterized by an average size of 50 nm and a volume fraction of 46%, was precipitated within the FCC matrix. This alloy exhibits excellent mechanical properties over a wide range of temperatures from 77 K to 1073 K. A yield strength of 1005 MPa, an ultimate tensile strength of 1620 MPa, and a tensile elongation of 36% were achieved at 77 K, with a maximum value of 4.8 GPa at the second stage of the work-hardening rate. The alloy maintains a basically consistent yield strength of approximately 800 MPa from 298 K to 973 K, showcasing significant strain-hardening capabilities, with values of 2.5 GPa, 3.7 GPa, and 4.8 GPa at 873 K, 298 K, and 77 K, respectively. Microscopic analysis revealed that at room and cryogenic temperatures, multilayer stacking faults (SFs), SF bands, and SF networks, rather than twins, effectively stored a large number of dislocations and impeded dislocation movement, thereby enhancing the work-hardening ability of the alloy. Furthermore, at 773 K, the primary deformation mechanism involved high-density dislocation walls (HDDWs) consisting of dislocation tangles and SF lines. As the temperature rose to 973 K, the work-hardening process was influenced by the APB shearing mechanism (in the form of dislocation pairs), SF lines, and microtwins generated through atomic rearrangement. This study not only provides valuable insights for the development of new oxidation-resistant superalloys but also enhances our understanding of high-temperature deformation mechanisms. Full article
14 pages, 6043 KiB  
Article
Phase Transformations after Heat Treating an As-Cast Fe-30Mn-8.8Al-0.3Si-0.15C Steel
by Victor M. Lopez-Hirata, Eduardo Perez-Badillo, Maribel Leticia Saucedo-Muñoz, Felipe Hernandez-Santiago and Jose David Villegas-Cardenas
Metals 2024, 14(7), 748; https://doi.org/10.3390/met14070748 - 25 Jun 2024
Viewed by 346
Abstract
The phase transformations in an as-cast Fe-30Mn-8.8Al-0.3Si-0.15C steel were analyzed experimentally and numerically with a Calphad-based method during heat treatment. The nonequilibrium phases were determined using the Thermo-Calc Scheil module and the equilibrium phases with Themo-Calc based on the steel chemical composition. The [...] Read more.
The phase transformations in an as-cast Fe-30Mn-8.8Al-0.3Si-0.15C steel were analyzed experimentally and numerically with a Calphad-based method during heat treatment. The nonequilibrium phases were determined using the Thermo-Calc Scheil module and the equilibrium phases with Themo-Calc based on the steel chemical composition. The precipitated phases were analyzed with TC-PRISMA using the chemical composition, nucleation site, and temperature among other factors. An ingot of this chemical composition was vacuum-melted using pure elements under an Ar gas atmosphere. As-cast steel specimens were annealed and solution-treated, quenched, and then aged at different temperatures. Heat-treated specimens were analyzed by different techniques. The results indicated that the microconstituents are the α and γ phases for the as-cast, homogenized, and quenched conditions. The main difference among these conditions is the distribution and size of the γ phase, which produced a change in hardness from 209 to 259 VHN. In contrast, the aging treatment at 750 °C caused a decrease in hardness from 492 to 306 VHN, which is attributable to the increase in volume fraction of the γ phase. On the other hand, the aging treatment at 550 °C promoted precipitation hardening from 259 to 649 VHN because of the κ precipitate formation. The calculated results for the different heat treatments with the Calphad-based method agreed well with the experimental ones. In addition, the intragranular precipitation of the κ phase could be simulated using the nucleation and growth and coarsening mechanisms based on a Calphad method. Full article
(This article belongs to the Special Issue Heat Treatment, Microstructures, and Mechanical Properties of Metallic Materials)
21 pages, 7490 KiB  
Article
Influence of the Material Production Route on the Material Properties and the Machinability of the Lead-Free Copper-Zinc-Alloy CuZn40 (CW509L)
by Kilian Brans, Stefan Kind, Markus Meurer and Thomas Bergs
Metals 2024, 14(7), 747; https://doi.org/10.3390/met14070747 - 25 Jun 2024
Viewed by 170
Abstract
To improve the machinability properties of CuZn-alloys, these are alloyed with the element lead. Due to its toxicity, a variety of legislative initiatives aim to reduce the lead content in CuZn-alloys, which results in critical machinability problems and a reduction in the productivity [...] Read more.
To improve the machinability properties of CuZn-alloys, these are alloyed with the element lead. Due to its toxicity, a variety of legislative initiatives aim to reduce the lead content in CuZn-alloys, which results in critical machinability problems and a reduction in the productivity of machining processes. Basically, there are two ways to solve the critical machinability problems when machining lead-free CuZn-alloys: optimizing the machinability of lead-free materials on the material side or adapting the processes and the respective process parameters. In this study, the focus is on material-side machinability optimization by investigating the influence of a targeted variation in the process chain in the material production route. To evaluate the influence of the material production route, the brass alloy CuZn40 (CW509L) was produced in four variants by varying the degree of work hardening and the use of heat treatments, and all four variants were evaluated in terms of their machinability. To evaluate the machinability, the cutting force components, the chip temperature, the chip formation, and the chip shape were analyzed. Clear influences of the material production route were identified, particularly with regard to the chip formation mechanisms and the resulting chip shape. Full article
(This article belongs to the Special Issue Advances in Copper, Copper Alloys and Their Processing)
29 pages, 17115 KiB  
Article
Optimizing Rolling Strategies for API 5L X80 Steel Heavy Plates Produced by Thermomechanical Processing in a Reversible Single-Stand Mill
by Luiz Gustavo de Oliveira Abreu, Geraldo Lúcio de Faria, Ricardo José de Faria, Daniel Bojikian Matsubara and Rodrigo Rangel Porcaro
Metals 2024, 14(7), 746; https://doi.org/10.3390/met14070746 - 25 Jun 2024
Viewed by 184
Abstract
This study focuses on advancing the production of predominantly bainitic heavy plates to meet the API 5L X80 standard. The investigation involves a thorough evaluation of the influence of rolling parameters and austenite conditioning on both microstructural characteristics and mechanical properties. Accurate specifications [...] Read more.
This study focuses on advancing the production of predominantly bainitic heavy plates to meet the API 5L X80 standard. The investigation involves a thorough evaluation of the influence of rolling parameters and austenite conditioning on both microstructural characteristics and mechanical properties. Accurate specifications for chemical composition, processing temperatures, and mean deformations were established using mathematical models and bibliographical references. Four rolling conditions were performed in a reversible single-stand mill, allowing for comprehensive comparison and critical analysis. Microstructural and mechanical characterizations were performed utilizing several techniques, including optical microscopy (OM), scanning electron microscopy (SEM), tensile tests, Charpy impact tests, and hardness tests to ensure adherence to API 5L standards. Additionally, the SEM-EBSD (electron backscattered diffraction) technique was employed for a complementary analysis. The EBSD analysis included crystallographic misorientation maps, mean kernel misorientation parameters (𝜗), low- and high-angle grains boundaries, mean equivalent diameter, and evaluation of the contribution of different strengthening mechanisms to yield strength. Results underscored the significant influence of austenite conditioning on both microstructure and mechanical properties. Considering the specificities of a reversible single-stand mill, it was concluded that, unlike the classic approach for ferritic or ferritic–pearlitic HSLA (high-strength low-alloy steel), when a product with a predominantly bainitic microstructure is required, the accumulated deformation in the austenite during the finishing rolling stage, as well as its temperature, must be meticulously controlled. It was shown that the greater the deformation and the lower the temperature, the more favorable the scenario for the undesired polygonal ferrite formation, which will deteriorate the material’s performance. Furthermore, an optimized production route was identified and adapted to the specificities of the employed rolling mill. The presented data have great importance for researchers, manufacturers, and users of API 5L X80 heavy plates. Full article
(This article belongs to the Section Metal Casting, Forming and Heat Treatment)
26 pages, 2914 KiB  
Article
Modeling of Zirconium Atom Redistribution and Phase Transformation Coupling Behaviors in U-10Zr-Based Helical Cruciform Fuel Rods under Irradiation
by Xingdi Chen, Zhexiao Xie, Xiaoxiao Mao and Shurong Ding
Metals 2024, 14(7), 745; https://doi.org/10.3390/met14070745 - 24 Jun 2024
Viewed by 256
Abstract
Uranium–zirconium metal-based Helical Cruciform Fuels (HCFs) have shown a promising prospect for their use in advanced nuclear reactors. However, during irradiation, dual-phase coexistence and the spatial heterogeneous distribution of zirconium atoms occur at higher powers, affecting the thermo-mechanical coupling behaviors and safety of [...] Read more.
Uranium–zirconium metal-based Helical Cruciform Fuels (HCFs) have shown a promising prospect for their use in advanced nuclear reactors. However, during irradiation, dual-phase coexistence and the spatial heterogeneous distribution of zirconium atoms occur at higher powers, affecting the thermo-mechanical coupling behaviors and safety of fuel elements and assemblies. In this study, based on the phase-field approach, the coupled multi-field governing equations to describe the zirconium diffusion and phase evolution for U-Zr metallic fuels are improved. Furthermore, the corresponding numerical algorithms and procedures for multi-field coupling calculations are developed. The numerical predictions of zirconium atom fraction are in good agreement with the relevant experimental results, validating the developed models, algorithms and programs. The zirconium atom redistribution and phase transformation coupling behaviors in high-power U-10wt%Zr-based HCF rods are also obtained. Moreover, the complex evolution mechanisms of multi-field variables are analyzed. The results indicate the following: (1) the irradiation enhancement of the thermal mobility and chemical mobility plays a critical role in the redistribution of Zr atoms; (2) the multi-field results of HCF rods have helical symmetric characteristics; (3) the contribution competitions of the temperature gradient and chemical potential gradient within the α phase and γ phase significantly influence the zirconium-atom redistribution, with the zirconium-rich zones formed in the elbow region and the zirconium-poor zones appearing inside. These research efforts supply a foundation for the further involvement of mechanical fields in multi-field coupling computation. Full article
(This article belongs to the Special Issue Advances in Metallic Nuclear Reactor Materials)
24 pages, 3790 KiB  
Article
Radiation Techniques for Tracking the Progress of the Hydrometallurgical Leaching Process: A Case Study of Mn and Zn
by Nelson Rotich Kiprono, Anna Kawalec, Bartlomiej Klis, Tomasz Smolinski, Marcin Rogowski, Paweł Kalbarczyk, Zbigniew Samczynski, Maciej Norenberg, Beata Ostachowicz, Monika Adamowska, Wojciech Hyk and Andrzej G. Chmielewski
Metals 2024, 14(7), 744; https://doi.org/10.3390/met14070744 - 24 Jun 2024
Viewed by 334
Abstract
With advancements in hardware and software, non-destructive radiometric analytical methods have become popular in a wide range of applications. A typical case is the study of the leaching process of metals from mineral ores and mine tailings. The objective of the current study [...] Read more.
With advancements in hardware and software, non-destructive radiometric analytical methods have become popular in a wide range of applications. A typical case is the study of the leaching process of metals from mineral ores and mine tailings. The objective of the current study was to develop a radiometric method based on neutron activation analysis (NAA), in particular, delayed gamma neutron activation analysis (DGNAA), to monitor the process of Mn and Zn leaching from Ti ore, Cu mine tailings, and Zn-Pb mine tailings. The DGNAA method was performed using a neutron source: a deuterium-tritium (D-T) neutron generator for Mn and a MARIA research nuclear reactor for Zn. Laboratory-scale Mn leaching from Ti ores, Cu tailings, and Zn-Pb tailings was investigated using delayed gamma-rays of 56Mn (half-life of 2.6 h). The dissolution efficiencies of Mn were found to increase with interaction time and HCl concentration (1 to 5 M) and to vary with the leaching temperature (22.5 to 110 °C). Such results were found to agree with those obtained by total reflection X-ray fluorescence (TXRF) spectrometry for the same samples. 65Zn (half-life of 244 days) was chosen to investigate real-time/online leaching of Zn in Ti ore, Cu tailings, and Zn-Pb tailings. During online monitoring, Zn recovery was also reported to increase with increased leaching time. After approximately 300 min of leaching, 80%, 79%, and 53% recovery of Zn in Zn-Pb tailings, Ti ore, and Cu tailings, respectively, were reported. Theoretically, developed mathematical prediction models for 65Zn radiotracer analysis showed that the spherical diffusion model requires much less time to attain saturation compared to the linear diffusion model. The results of NAA for Zn were compared with those obtained by handheld X-ray fluorescence (handheld-XRF) and TXRF analysis. The analyzed samples encompassed leached Ti ore, Cu tailings, and Zn-Pb tailings which were subjected to different conditions of leaching time, temperature, and HCl concentrations. The XRF analysis confirmed that the leaching efficiencies of Zn rise with the increase in leaching time and HCl concentration and fluctuate with leaching temperature. The developed approach is important and can be applied in laboratories and industrial setups for online monitoring of the recovery of any element whose isotopes can be activated using neutrons. The efficiency of the metal-recovery process has a direct impact on the normal operation and economic advantages of hydrometallurgy. Full article
(This article belongs to the Special Issue Recovery and Recycling of Metals from the Wastes of New Energy Industry)
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