Alloys

15 pages, 4479 KB

Open AccessArticle

Modeling and Analysis of Corrosion of Aluminium Alloy 6060 Using Electrochemical Impedance Spectroscopy (EIS)

by Aikaterini Baxevani, Eleni Lamprou, Azarias Mavropoulos, Fani Stergioudi, Nikolaos Michailidis and Ioannis Tsoulfaidis

Alloys 2025, 4(3), 17; https://doi.org/10.3390/alloys4030017 - 29 Aug 2025

Abstract

Aluminum is widely used in many industries like automotive, aerospace and construction because of its low weight, good mechanical strength and resistance to corrosion. This resistance comes mainly from a passive oxide layer that forms on its surface. However, when aluminum is exposed [...] Read more.

Aluminum is widely used in many industries like automotive, aerospace and construction because of its low weight, good mechanical strength and resistance to corrosion. This resistance comes mainly from a passive oxide layer that forms on its surface. However, when aluminum is exposed to harsh environments, especially those containing chloride ions in marine environments, this layer can break down and lead to localized corrosion, such as pitting. This study examined aluminum profiles at different processing stages, including homogenization and aging, anodizing and pre-anodizing followed by painting. Corrosion behavior of samples was studied using two electrochemical methods. Potentiodynamic polarization was used to measure corrosion rate and current density, while Electrochemical Impedance Spectroscopy (EIS) helped to understand the behavior of protective layers and corrosion progression. Tests were carried out in a 3.5% NaCl solution at room temperature. EIS results were analyzed using equivalent circuit models to better understand electrochemical processes. Overall, this study shows how surface treatment affects corrosion resistance and highlights advantages of EIS in studying corrosion behavior in a more reliable and repeatable way. Full article

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16 pages, 4982 KB

Open AccessReview

The Role of Metal Foams for Sustainability and Energy Transition

by Alessandra Ceci, Girolamo Costanza, Fabio Giudice, Andrea Sili and Maria Elisa Tata

Alloys 2025, 4(3), 16; https://doi.org/10.3390/alloys4030016 - 13 Aug 2025

Abstract

The global pursuit of a sustainable and decarbonized energy landscape requires the development of novel materials capable of supporting lightweight construction, advanced energy conversion, storage, and thermal management technologies. Among these, metal foams have emerged as a versatile class of porous materials, offering [...] Read more.

The global pursuit of a sustainable and decarbonized energy landscape requires the development of novel materials capable of supporting lightweight construction, advanced energy conversion, storage, and thermal management technologies. Among these, metal foams have emerged as a versatile class of porous materials, offering a unique combination of low density, high surface area, three-dimensional (3D) interconnected porosity, and favorable thermal and electrical conductivities. These attributes make them highly suitable for a broad range of applications critical to the ongoing energy transition, assuming an increasingly central role in enabling clean, efficient, and resilient energy infrastructures. From this key perspective, the present review highlights the relevance of the adoption of metal foams in several fields crucial for the energy transition. By presenting methodologies and outcomes of research results, mainly from the last five years, the paper underscores the potential of low-weight, high-surface, and high-performance porous materials in contemporary and future industry, supporting sustainable development and, more generally, energy transition and circular economy. The approach also aims to minimize negative impacts and promote sustainability, for example, by recycling and transforming waste materials. Full article

(This article belongs to the Special Issue Lightweight Alloys)

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12 pages, 7595 KB

Open AccessArticle

Reactive Sintering of Cemented Carbides

by Victor I. Stanciu, Alexandre Mégret, Anne Mouftiez, Véronique Vitry and Fabienne Delaunois

Alloys 2025, 4(3), 15; https://doi.org/10.3390/alloys4030015 - 25 Jul 2025

Abstract

Cemented carbides are among the primary materials for tools and wear parts. Today, energy prices and carbon emissions have become key concerns worldwide. Cemented carbides consist of tungsten carbide combined with a binder, typically cobalt, nickel, or more recently, various high-entropy alloys. Producing [...] Read more.

Cemented carbides are among the primary materials for tools and wear parts. Today, energy prices and carbon emissions have become key concerns worldwide. Cemented carbides consist of tungsten carbide combined with a binder, typically cobalt, nickel, or more recently, various high-entropy alloys. Producing tungsten carbide involves reducing tungsten oxide, followed by carburization of tungsten at 1400 °C under a hydrogen atmosphere. The tungsten carbide produced is then mixed with the binder, milled to achieve the desired particle size, and granulated to ensure proper flow for pressing and shaping. This study aims to bypass the tungsten carburizing step by mixing tungsten, carbon, and cobalt; shaping the mixture; and then applying reactive sintering, which will convert tungsten into carbide and consolidate the parts. The mixtures were prepared by planetary ball milling for 10 h under different conditions. Tests demonstrated that tungsten carburization successfully occurs during sintering at 1450 °C for 1 h. The samples exhibit a typical cemented carbide microstructure, characterized by prismatic grains with an average size of 0.32 μm. Densification reached 92%, hardness is approximately 1800 HV30, and toughness is 10.9 ± 1.15 MPa·m^1/2. Full article

(This article belongs to the Special Issue New Alloys for Surface Engineered Coatings, Interfaces and Films)

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7 pages, 1424 KB

Open AccessArticle

Microstructure, Phase Transformation, and Mechanical Properties of Ni-Ti-Hf-La Alloys

by Dorjsuren Bolormaa and Maashaa Dovchinvanchig

Alloys 2025, 4(3), 14; https://doi.org/10.3390/alloys4030014 - 21 Jul 2025

Abstract

This research investigates the effects of the addition of the rare-earth element La on the microstructure, phase transformation, and mechanical properties of Ni₅₀Ti₃₀Hf_20−xLa_x (x = 0, 0.5, 1, 2) alloys. The results show that a primary [...] Read more.

This research investigates the effects of the addition of the rare-earth element La on the microstructure, phase transformation, and mechanical properties of Ni₅₀Ti₃₀Hf_20−xLa_x (x = 0, 0.5, 1, 2) alloys. The results show that a primary matrix composed of Ni-Ti-Hf and featuring La-rich second phases formed. The temperature at which the martensitic phase transformation starts decreases with an increase in La content. As the amount of La increases, hardness decreases slightly, while the elastic modulus increases. Full article

(This article belongs to the Topic Microstructure and Properties in Metals and Alloys, 3rd Volume)

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9 pages, 4257 KB

Open AccessArticle

Ultrasonic-Assisted Face Turning of C45 Steel: An Experimental Investigation on Surface Integrity

by Thanh-Trung Nguyen

Alloys 2025, 4(3), 13; https://doi.org/10.3390/alloys4030013 - 10 Jul 2025

Abstract

This study investigates the effect of ultrasonic vibration applied in the cutting speed direction on surface quality during face turning of C45 steel. The experiments were performed using an ultrasonic generator operating at a frequency of 20 kHz with an amplitude of approximately [...] Read more.

This study investigates the effect of ultrasonic vibration applied in the cutting speed direction on surface quality during face turning of C45 steel. The experiments were performed using an ultrasonic generator operating at a frequency of 20 kHz with an amplitude of approximately 10 µm. The cutting parameters used in the experiments included spindle speeds of 700, 1100, and 1300 rpm, feed rates of 0.1 and 0.15 mm/rev, while the depth of cut was fixed at 0.2 mm. Surface quality was evaluated based on the roughness parameters R_a and R_z, as well as surface topography was observed using a Keyence VHX-7000 digital microscope. The results show that ultrasonic-assisted face turning (UAFT) significantly improves surface finish, particularly in the central region of the workpiece where the cutting speed is lower and built-up edge (BUE) formation is more likely. The lowest R_a value recorded was 0.91 µm, representing a 71% reduction compared to conventional turning (CT). Furthermore, at the highest spindle speed (1300 rpm), the standard deviations of both R_a and R_z were minimal, indicating improved surface consistency due to the suppression of BUE by ultrasonic vibration. Topographical observations further confirmed that UAFT generated regular and periodic surface patterns, in contrast to the irregular textures observed in CT. Full article

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24 pages, 2492 KB

Open AccessReview

Impact of Niobium Reduction on the Microstructure and Properties of Alloy 625 Weld Overlay Claddings: A Review

by Reylina Garcia Tayactac, Mark Christian E. Manuel, Jaime P. Honra, Tiago Bohn Kaspary and Raimundo Cabral de Medeiros

Alloys 2025, 4(3), 12; https://doi.org/10.3390/alloys4030012 - 2 Jul 2025

Abstract

Alloy 625 is a widely utilized nickel-based superalloy known for its excellent mechanical strength and corrosion resistance in aggressive environments. However, its high niobium (Nb) content can lead to the formation of detrimental phases, such as Laves and MC carbides, during welding processes, [...] Read more.

Alloy 625 is a widely utilized nickel-based superalloy known for its excellent mechanical strength and corrosion resistance in aggressive environments. However, its high niobium (Nb) content can lead to the formation of detrimental phases, such as Laves and MC carbides, during welding processes, compromising the mechanical integrity and long-term performance of the weld overlay. This review systematically examines recent research findings on the implications of reducing Nb content in Alloy 625 weld overlays, particularly with respect to microstructure evolution, mechanical behavior, and corrosion performance. Key advancements, including the understanding of segregation behavior, solidification paths, and secondary phase formation, are presented based on recent studies. This paper aims to provide a discussion on the trade-offs and future directions for optimizing Alloy 625 weld overlay claddings through Nb content modification. Full article

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16 pages, 3210 KB

Open AccessArticle

Performance Improvement of Tin-Based Babbitt Alloy Through Control of Microstructure

by Zhang Wei, Honglin Shu, Gaixiao Qiao, Qunfeng Zeng, Guoping Wang and Qian Jia

Alloys 2025, 4(3), 11; https://doi.org/10.3390/alloys4030011 - 20 Jun 2025

Abstract

Babbitt alloys are among the most commonly used materials for sliding bearings. However, with the high speeds and heavy loads of modern machinery, as well as the demands of extreme working conditions, the temperature resistance, strength, and hardness of traditional Babbitt alloys are [...] Read more.

Babbitt alloys are among the most commonly used materials for sliding bearings. However, with the high speeds and heavy loads of modern machinery, as well as the demands of extreme working conditions, the temperature resistance, strength, and hardness of traditional Babbitt alloys are often insufficient to meet these requirements. To address this issue, it is essential to improve the properties of Babbitt alloys, particularly their performance at high temperatures. The present study explored a technical approach for incorporating copper powder to improve the high-temperature performance of Babbitt alloys. Copper powder was added to the traditional Babbitt alloy in mass percentages of 1, 2, 3, and 4%. After fabrication, the samples were examined using metallographic structure analysis, high-temperature compression testing, and friction and wear testing. The experiments investigated the effects of copper powder addition on the properties of the Babbitt alloy and determined the optimal amount of copper powder required to enhance its performance. Full article

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13 pages, 2488 KB

Open AccessArticle

Silicon and Manganese Effect on the Phase Composition of an Al-Fe Alloy and the Use of the ThermoCalc Software Complex for Thermodynamic Analysis

by Bakhtiyar Suleyev, Aristotel Issagulov, Ardak Dostayeva, Dastan Aubakirov and Togzhan Sultanbek

Alloys 2025, 4(2), 10; https://doi.org/10.3390/alloys4020010 - 30 May 2025

Abstract

This study examines the effect of silicon and manganese addition on the phase composition and electrical properties of Al-Fe alloys using both experimental methods and thermodynamic modeling with the ThermoCalc software package. This research focuses on the Al–Fe–Si–Mn system, which shows potential for [...] Read more.

This study examines the effect of silicon and manganese addition on the phase composition and electrical properties of Al-Fe alloys using both experimental methods and thermodynamic modeling with the ThermoCalc software package. This research focuses on the Al–Fe–Si–Mn system, which shows potential for developing conductive aluminum alloys with enhanced performance characteristics. It was found that when silicon and manganese are added in amounts up to 0.6%, the formation of intermetallic phases such as Al₈Fe₂Si and Al₁₅Mn₃Si₂ occurs. These phases significantly influence the electrical conductivity and mechanical stability of the alloy. Thermodynamic modeling proved effective in predicting phase formation, guiding the selection of alloy compositions, and optimizing heat treatment parameters. The optimal composition for a conductive aluminum alloy includes up to 0.8% Fe, 0.5% Si, and 0.6% Mn. Heat treatment in the range of 500–550 °C resulted in a favorable combination of strength, electrical conductivity, and thermal resistance. The findings support the use of Al–Fe–Si–Mn alloys in electrical and structural applications and demonstrate the value of combining computational and experimental approaches in alloy design. Full article

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11 pages, 3317 KB

Open AccessArticle

Corrosion Behavior of Zinc Wrought Alloy ZnAl15Cu1Mg (ZEP1510) as a Potential Substitute for Brass and Galvanized Steel

by Abdulkerim Karaman, Alexander Kremer and Michael Marré

Alloys 2025, 4(2), 9; https://doi.org/10.3390/alloys4020009 - 7 May 2025

Abstract

The increasing restriction of lead in industrial alloys, particularly in copper–zinc-based materials such as CuZn40Pb2, necessitates the development of environmentally safer alternatives. ZnAl15Cu1Mg (ZEP1510), a zinc-based wrought alloy composed of 15% aluminum, 1% copper, 0.03% magnesium, with the remainder being zinc, has emerged [...] Read more.

The increasing restriction of lead in industrial alloys, particularly in copper–zinc-based materials such as CuZn40Pb2, necessitates the development of environmentally safer alternatives. ZnAl15Cu1Mg (ZEP1510), a zinc-based wrought alloy composed of 15% aluminum, 1% copper, 0.03% magnesium, with the remainder being zinc, has emerged as a promising candidate for lead-free applications due to its favorable forming characteristics and corrosion resistance. This study investigates the performance of ZEP1510 compared to conventional leaded copper alloys and galvanized steel. Corrosion behavior was evaluated using neutral salt spray testing, cyclic climate chamber exposure, and electrochemical potential analysis in chloride- and sulfate-containing environments. ZEP1510 exhibited corrosion resistance comparable to brass and significantly better performance than galvanized steel in neutral and humid atmospheres. Combined with its low processing temperature and high recyclability, ZEP1510 presents itself as a viable and sustainable alternative to brass with lead for applications in sanitary, automotive, and electrical engineering industries. Full article

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13 pages, 5096 KB

Open AccessArticle

Quantitative Study of Internal Defects in Copper Iron Alloy Materials Using Computed Tomography

by Junli Guo, Qiang Hu and Kai Hu

Alloys 2025, 4(2), 8; https://doi.org/10.3390/alloys4020008 - 29 Apr 2025

Abstract

Semi-continuous casting is an important method for the large-scale production of high-strength conductive copper-iron (Cu-Fe) alloys in the future. However, serious peeling defects were found on the surface of cold-rolled strips during industrial trials. Due to the multi-step complexity of the manufacturing process [...] Read more.

Semi-continuous casting is an important method for the large-scale production of high-strength conductive copper-iron (Cu-Fe) alloys in the future. However, serious peeling defects were found on the surface of cold-rolled strips during industrial trials. Due to the multi-step complexity of the manufacturing process (from casting to final product), identifying the root cause of defect formation remains challenging. X-ray computed tomography (X-CT) was used to quantitatively characterize the pores and defects in the horizontal continuous casting Cu-Ni-Sn slab, the semi-continuous casting Cu-Fe alloy slab, and the hot-rolled slab of Cu-Fe, and the relationship between the defect characteristics and processes was analyzed. The results showed that the internal defect sphericity distribution of the Cu-Fe alloy slab after hot rolling was similar to that of the reference Cu-Ni-Sn slab. The main difference lies in the low sphericity range (<0.4). The volume of pore defects inside the Cu-Fe alloy after hot rolling was significantly larger than in the reference sample, with a 52-fold volume difference. This phenomenon may be the source of surface-peeling defects in the subsequent cold-rolling process. The occurrence of internal defects in the Cu-Fe alloy is related to both the composition characteristics and casting processes of the Cu-Fe alloy; on the other hand, it is also related to the hot-rolling process. Full article

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9 pages, 9335 KB

Open AccessCommunication

Effect of Nd on Stacking Fault Energy in Pure Copper: A First-Principles and HRTEM Study

by Mingyi Zhang, Yang Li, Chongyuan Huang, Puyou Ying, Yong Huan, Chong Zhao, Chi Xiao and Fei Liu

Alloys 2025, 4(2), 7; https://doi.org/10.3390/alloys4020007 - 28 Apr 2025

Abstract

Stacking fault energy (SFE) can significantly affect the plastic deformation mechanism of metal materials and then affect their mechanical properties. Changing the stacking fault energy by microalloying rare earth elements is an effective means to control the plastic deformation mechanism and optimize the [...] Read more.

Stacking fault energy (SFE) can significantly affect the plastic deformation mechanism of metal materials and then affect their mechanical properties. Changing the stacking fault energy by microalloying rare earth elements is an effective means to control the plastic deformation mechanism and optimize the mechanical properties of the metal materials. Based on first principles, the HRTEM technique and GPA method, the effects of Nd content on the SFE and microstructure of Cu alloys were studied. The results show that the Nd element can significantly reduce the SFE of pure copper. But the change in the Nd element content has little influence on the SFE of the alloy. In addition, with the increase in Nd content, the grain size and twin size are refined. The GPA results show that strong tensile strain is formed inside the twin, and alternating tensile strain and compressive strain structures are formed on the (-11-1) plane at the tip of the twin. Full article

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14 pages, 10083 KB

Open AccessArticle

Characteristics of Separations in Fracture After Crack Tip Opening Displacement Tests of Low-Carbon Microalloyed Offshore Steel S460MLO

by Eugene Goli-Oglu, Marco Palombo and Andrei Filatov

Alloys 2025, 4(2), 6; https://doi.org/10.3390/alloys4020006 - 23 Apr 2025

Abstract

Using the results from testing industrial batches of 23 mm steel heavy plates after thermomechanical rolling and subsequent post-weld heat treatment, the patterns of fatigue crack formation in the fracture specimens during CTOD (Crack Tip Opening Displacement) testing for fracture toughness are investigated. [...] Read more.

Using the results from testing industrial batches of 23 mm steel heavy plates after thermomechanical rolling and subsequent post-weld heat treatment, the patterns of fatigue crack formation in the fracture specimens during CTOD (Crack Tip Opening Displacement) testing for fracture toughness are investigated. Visual, microstructural, and fractographic studies of the nature of fracture formation and the surface of the secondary separations have been conducted. The probable causes of the manifestation of the potential “pop-in” effect on the load–displacement diagrams of the notch opening displacement are described, as well as its potentially negative impact on the interpretation of test results. Full article

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10 pages, 4065 KB

Open AccessArticle

Electronic Correlations in Ferromagnetic Heusler Alloy ln₂MnW: Insights from First-Principles Calculations

by Abdul Munam Khan and Uzma Zahoor

Alloys 2025, 4(2), 5; https://doi.org/10.3390/alloys4020005 - 28 Mar 2025

Abstract

First-principles calculations were carried out to investigate the physical properties of the full-Heusler compound In₂MnW. The WIEN2K code was utilized with various approximations, such as GGA and GGA+U, to analyze its structural, electronic, and magnetic properties. The unit cell was optimized [...] Read more.

First-principles calculations were carried out to investigate the physical properties of the full-Heusler compound In₂MnW. The WIEN2K code was utilized with various approximations, such as GGA and GGA+U, to analyze its structural, electronic, and magnetic properties. The unit cell was optimized to determine the ground-state energy. The calculated formation enthalpy (ΔH) of In₂MnW is −0.189 eV, indicating its thermodynamic stability due to the negative value. Band structure analysis using both potentials confirms the compound’s metallic nature, which is further supported by total density of states calculations. The total magnetic moment is found to be 4.3 µB, which slightly increases to 4.4 µB when the U parameter is included. These findings suggest that In₂MnW demonstrates metallic ferromagnetic behavior, highlighting its potential as a promising ferromagnetic material for mass storage applications. Full article

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12 pages, 22226 KB

Open AccessArticle

Research on the Microstructure Evolution of TC4 Titanium Alloy Joint Fabricated by Continuous Drive Friction Welding

by Shanshan Cui, Shiqing Wang, Yiqiang Zhang, Guodong Wen and Wei Qiang

Alloys 2025, 4(1), 4; https://doi.org/10.3390/alloys4010004 - 14 Mar 2025

Abstract

In this paper, TC4 titanium alloy pipes were achieved by continuous drive friction welding, metallographic microscope and microhardness tester were used to evaluate the microstructure and the hardness of the joints, and the effect of friction pressure on the microstructure was studied. Under [...] Read more.

In this paper, TC4 titanium alloy pipes were achieved by continuous drive friction welding, metallographic microscope and microhardness tester were used to evaluate the microstructure and the hardness of the joints, and the effect of friction pressure on the microstructure was studied. Under the selected welding parameters, all the joints have good morphology. The martensite is formed at the weld zone and the flash, which leads to a higher hardness on the weld zone. With the increase of friction pressure, the width of the weld zone, the grain size and LAGB (low angle grain boundary) at the weld zone decreases. In addition, dynamic recrystallization increases first, but when the friction pressure reaches 65 MPa, the deformation dominates. Full article

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9 pages, 2363 KB

Open AccessArticle

Lattice Dynamics and Thermal Properties of Ti_xZr_1-xNiSn Half-Heusler Alloys

by Prince Sharma

Alloys 2025, 4(1), 3; https://doi.org/10.3390/alloys4010003 - 26 Feb 2025

Cited by 7

Abstract

Half-Heusler alloys are promising materials for thermoelectric applications, yet the impact of the compositional disorder on their lattice dynamics remains incompletely understood. This study investigates the effect of systematic Zr substitution on the lattice dynamics and thermal properties of Ti_xZr_1-x [...] Read more.

Half-Heusler alloys are promising materials for thermoelectric applications, yet the impact of the compositional disorder on their lattice dynamics remains incompletely understood. This study investigates the effect of systematic Zr substitution on the lattice dynamics and thermal properties of Ti_xZr_1-xNiSn half-Heusler alloys using first-principles calculations. Through careful analysis of phonon dispersions, density of states, and thermodynamic properties, it is revealed that Zr substitution (25%, 50%, and 75%) introduces minimal structural distortion while enhancing system stability. It is shown that increasing Zr content systematically modifies the phonons, particularly affecting the high-frequency optical modes above 5 THz. Notably, with Zr content, these findings provide valuable insights for tailoring the thermal properties of half-Heusler alloys for high-temperature applications in thermoelectric devices and components. Full article

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14 pages, 2535 KB

Open AccessArticle

Oxidation Kinetics of FeCr and FeCrAl Alloys: Influence of Secondary Processes (Continuation)

by Irakli Nakhutsrishvili and Revaz Tevzadze

Alloys 2025, 4(1), 2; https://doi.org/10.3390/alloys4010002 - 27 Jan 2025

Abstract

This paper discusses the influence of the secondary processes of reaction product evaporation and the reduction of the effective diffusion area into the scale on the kinetics (change in sample mass–time) of the high-temperature oxidation processes, in air, of alumina- and chromia-forming alloys. [...] Read more.

This paper discusses the influence of the secondary processes of reaction product evaporation and the reduction of the effective diffusion area into the scale on the kinetics (change in sample mass–time) of the high-temperature oxidation processes, in air, of alumina- and chromia-forming alloys. Full article

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18 pages, 9907 KB

Open AccessArticle

Effect of Microstructure on Multiscale Mechanical Properties of Scalmalloy Produced by Powder Bed Fusion-Laser Beam

by Huixing (Hannah) Zhang, Caitlin E. R. Green, Maria J. Lodeiro, Peter Woolliams, Ken P. Mingard and Antony T. Fry

Alloys 2025, 4(1), 1; https://doi.org/10.3390/alloys4010001 - 30 Dec 2024

Cited by 1

Abstract

For additive manufactured parts, it is important to measure homogeneity and demonstrate representative parts can be printed faster while maintaining key mechanical properties. In this work, a multiscale characterization of microstructural and mechanical properties was carried out to gain a thorough understanding of [...] Read more.

For additive manufactured parts, it is important to measure homogeneity and demonstrate representative parts can be printed faster while maintaining key mechanical properties. In this work, a multiscale characterization of microstructural and mechanical properties was carried out to gain a thorough understanding of a range of powder bed fusion-laser beam (PBF-LB)-manufactured Scalmalloy for future optimization of the processing parameters. The relationship between microstructure, including porosity, grain structure, and precipitates, and mechanical properties, is investigated. The stress-relieved samples were characterized mainly using scanning electron microscopy (SEM) suite, uniaxial tensile tests and nanoindentation. The results show the multiple strengthening mechanisms in Scalmalloy, including solid solution strengthening, grain size, precipitates and dislocations strengthening, demonstrated through a combination of the nanoindentation measurements with microstructural analysis at the local scale. The current work suggests potential mechanisms for further improvement of the strength and ductility in PBF-LB-Scalmalloy. Full article

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18 pages, 11699 KB

Open AccessArticle

Evolution of Precipitates and Microhardness of L-PBF Inconel 625 Through Relevant Thermal Treatment

by Tahmina Keya, Ralf D. Fischer, Mohanish Andurkar, Scott M. Thompson, Valentina O’Donnell, John Gahl and Barton C. Prorok

Alloys 2024, 3(4), 295-312; https://doi.org/10.3390/alloys3040018 - 17 Dec 2024

Cited by 1

Abstract

Laser powder bed fusion (L-PBF) is a metal additive manufacturing (AM) technique that produces a unique microstructure significantly different from wrought microstructure. Inconel 625 (IN625) is an alloy widely used to manufacture complex parts, but it comes with its own unique challenges. The [...] Read more.

Laser powder bed fusion (L-PBF) is a metal additive manufacturing (AM) technique that produces a unique microstructure significantly different from wrought microstructure. Inconel 625 (IN625) is an alloy widely used to manufacture complex parts, but it comes with its own unique challenges. The alloy is prone to precipitation under elevated temperatures, which makes designing suitable heat treatment to tailor the desired microstructure and mechanical properties critical. Traditional heat treatment for wrought IN625 cannot be applied to L-PBF IN625; therefore, it is vital to understand the evolution of precipitates on the way to complete recrystallization. This study focuses on these precipitates in IN625 produced by the L-PBF technique. Heat treatments at 700 °C, 900 °C, and 1050 °C were performed separately to encourage the precipitation of strengthening γ″, the detrimental δ phase, and the dissolution of precipitates, respectively. γ″ precipitates were found in the as-printed condition and at 700 °C. δ precipitates were detected at 700 and 900 °C. Carbides and Al-rich oxides were observed in all conditions of L-PBF IN625. Texture analysis showed grain growth along the build direction with strong (100) texture at temperatures up to 900 °C. Weak and random texture with equiaxed grains was observed at 1050 °C, which is similar to wrought IN625. Full article

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14 pages, 15922 KB

Open AccessArticle

Influence of Subsequent Heat Treatment on Fatigue Behavior of Shear-Cut Electrical Steel Sheets

by Albin Gottwalt-Baruth, Paul Kubaschinski, Manuela Waltz and Ulrich Tetzlaff

Alloys 2024, 3(4), 281-294; https://doi.org/10.3390/alloys3040017 - 25 Nov 2024

Abstract

The fatigue behavior of a fully processed, non-oriented electrical steel sheet is investigated in dependence on shear-cutting parameters and a subsequent heat treatment. For this, stress-controlled fatigue tests are performed before and after annealing at 700 °C for a total of six different [...] Read more.

The fatigue behavior of a fully processed, non-oriented electrical steel sheet is investigated in dependence on shear-cutting parameters and a subsequent heat treatment. For this, stress-controlled fatigue tests are performed before and after annealing at 700 °C for a total of six different shear-cutting settings. For all parameters, the fatigue strength of shear-cut sheets is improved by the heat treatment. This is due to reduction in a large part of the strain hardening region as well as the reduction in tensile residual stresses. Both were introduced during shear cutting and act detrimental to the fatigue strength. However, the intensity of this improvement depends on the shear-cutting parameters. This is related to the corresponding edge surfaces characteristically being formed during shear cutting. Specimens cut with a worn cutting tool show a more pronounced increase in fatigue life. In contrast, specimens produced with a sharp-edged cutting tool and high cutting clearance hardly benefit from the heat treatment. This appears to be caused by differences in surface topography, in particular coarse topographical damage in the form of grain breakouts. If these occur during shear cutting, the crack formation is not significantly delayed by additional annealing. Full article

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