Research

11 pages, 6083 KiB

Open AccessArticle

Novel Magnesium Nanocomposite for Wire-Arc Directed Energy Deposition

by Hajo Dieringa, Maria Nienaber, Danai Giannopoulou, Jonas Isakovic, Jan Bohlen, Milli Suchita Kujur, Noomane Ben Khalifa, Thomas Klein and Stefan Gneiger

Materials 2024, 17(2), 500; https://doi.org/10.3390/ma17020500 - 20 Jan 2024

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Abstract

Magnesium alloys play an essential role in metallic lightweight construction for modern mobility applications due to their low density, excellent specific strength, and very good castability. For some years now, degradable implants have also been made from magnesium alloys, which, thanks to this [...] Read more.

Magnesium alloys play an essential role in metallic lightweight construction for modern mobility applications due to their low density, excellent specific strength, and very good castability. For some years now, degradable implants have also been made from magnesium alloys, which, thanks to this special functionality, save patients a second surgery for explantation. New additive manufacturing processes, which are divided into powder-based and wire-based processes depending on the feedstock used, can be utilized for these applications. Therefore, magnesium alloys should also be used here, but this is hardly ever implemented, and few literature reports exist on this subject. This is attributable to the high affinity of magnesium to oxygen, which makes the use of powders difficult. Therefore, magnesium wires are likely to be used. In this paper, a magnesium-based nanocomposite wire is made from an AM60 (Mg-6Al-0.4Mn) (reinforced with 1 wt% AlN nanoparticles and containing calcium to reduce flammability), using a high-shear process and then extruded into wires. These wires are then used as feedstock to build up samples by wire-arc directed energy deposition, and their mechanical properties and microstructure are examined. Our results show that although the ductility is reduced by adding calcium and nanoparticles, the yield strength in the welding direction and perpendicular to it is increased to 131 MPa. Full article

(This article belongs to the Special Issue The Additive Manufacturing of Metallic Alloys)

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12 pages, 7545 KiB

Open AccessArticle

Effect of Aging Temperature on the Microstructure and Mechanical Properties of a Novel β Titanium Alloy

by Wei Xiang, Wuhua Yuan, Hao Deng, Hengjun Luo, Longqing Chen and Weidong Yin

Materials 2023, 16(23), 7393; https://doi.org/10.3390/ma16237393 - 28 Nov 2023

Viewed by 708

Abstract

High-strength metastable β titanium alloys are promising structural materials to be used in aviation industries. In order to achieve a high strength level, solid solution treatment within β region and subsequent low-temperature aging are usually necessary to obtain fine α precipitates. The selection [...] Read more.

High-strength metastable β titanium alloys are promising structural materials to be used in aviation industries. In order to achieve a high strength level, solid solution treatment within β region and subsequent low-temperature aging are usually necessary to obtain fine α precipitates. The selection of the aging temperature is considered critical to the mechanical performance of metastable β titanium alloys. In this work, we investigated the effect of aging temperature on the microscopic structure and mechanical properties of a novel type of titanium alloy TB18 (Ti-4.5Al-5Mo-5V-6Cr-1Nb). A series of aging treatments were conducted on TB18 specimens at 510 °C, 520 °C, 530 °C, and 540 °C after the solid solution treatment at 870 °C. On the basis of the systematic results of scanning electron microscope and transmission electron microscope, the behavior of the α phases affected by the varied aging temperatures were studied. As the aging temperature rose, the grain width of the α phase increased from 60 nm (510 °C) to 140 nm (540 °C). For the TB18 samples aged at 510 °C and 540 °C, the tensile strength/yield strength/impact toughness values were 1365 ± 3 MPa/1260 ± 0.9 MPa/26.5 ± 1.2 J/cm² and 1240 ± 0.9 MPa/1138 ± 0.8 MPa/36.2 ± 1.3 J/cm², respectively. As a result, the tensile performance and the grain width of the α phase agreed well with the Hall–Petch relationship. This work offers valuable support for both theoretical analyses and the heat treatment strategies on the novel TB18 titanium alloy. Full article

(This article belongs to the Special Issue The Additive Manufacturing of Metallic Alloys)

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17 pages, 8472 KiB

Open AccessArticle

Influence of Ion Nitriding on Microstructure and Properties of Haynes 282 Nickel Superalloy Specimens Produced Using DMLS Technique

by Ryszard Sitek, Krzysztof Kulikowski, Krystian Paradowski, Kamil Gancarczyk, Monika Losertová, Akira Kobayashi, Joanna Moneta and Janusz Kamiński

Materials 2023, 16(14), 5020; https://doi.org/10.3390/ma16145020 - 15 Jul 2023

Cited by 1 | Viewed by 963

Abstract

The paper investigates the influence of the ion-nitriding process on the microstructure, corrosion resistance, and tensile strength at elevated temperatures of Haynes 282 nickel superalloy specimens produced by the Direct Metal Laser Sintering (DMLS) technique. The study was performed for two conditions, i.e., [...] Read more.

The paper investigates the influence of the ion-nitriding process on the microstructure, corrosion resistance, and tensile strength at elevated temperatures of Haynes 282 nickel superalloy specimens produced by the Direct Metal Laser Sintering (DMLS) technique. The study was performed for two conditions, i.e., as-built by DMLS method and as-built by DMLS method + covered by a layer containing CrN + Cr₂N phases. An analysis of the surface morphology revealed that the ion-nitriding process significantly affects the physical and chemical phenomena occurring on the specimen’s surface. The XRD measurement of the specimens showed that preparing them with the DMLS method as well as following a nitriding process produced residual tensile stresses. Based on the measurement of the nanohardness distribution through the layer approximatively of 7 μm in width and the superalloys substrate, the results of the nanohardness showed the maximum values of 27 GPa and 13.5 GPa for the nitrided layer and the substrate, respectively. The surface protection from the nitrided layer proved a positive effect on the corrosion resistance of the DMLS specimens in the solution of 0.1 M Na₂SO₄ + 0.1 M NaCl at room temperature. The results of the tensile tests at 750 °C showed that the ion-nitriding process did not significantly affect the elevated-temperature tensile strength of the superalloy specimens produced with the DMLS technique. Full article

(This article belongs to the Special Issue The Additive Manufacturing of Metallic Alloys)

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15 pages, 6356 KiB

Open AccessArticle

A Finite Element Analysis on the Effect of Scanning Pattern and Energy on Residual Stress and Deformation in Wire Arc Additive Manufacturing of EH36 Steel

by Muhammad Hassaan Ali and You Sung Han

Materials 2023, 16(13), 4698; https://doi.org/10.3390/ma16134698 - 29 Jun 2023

Cited by 1 | Viewed by 886

Abstract

Wire arc additive manufacturing (WAAM) is a metal additive manufacturing (AM) technique that has a high throughput and has seen a potential interest for replacing currently available subtractive manufacturing techniques. Contrary to other metal AM machines, WAAM rigs can be built using existing [...] Read more.

Wire arc additive manufacturing (WAAM) is a metal additive manufacturing (AM) technique that has a high throughput and has seen a potential interest for replacing currently available subtractive manufacturing techniques. Contrary to other metal AM machines, WAAM rigs can be built using existing welding plants and using welding wire as feedstock, thus, making it a cheap and viable manufacturing technique for a number of industries, such as the maritime industry. However, the effects of AM parameters, such as the scanning pattern and energy, on the residual stress and deformation, are still not completely understood. In this work, a finite element (FE) study has been conducted to understand the influence of different scanning patterns (alternate, in-out, raster and zigzag) and energies on residual stress and warpage. Analyses show that the in-out scanning pattern leads to the highest residual stress, while the zigzag pattern results in the lowest residual stress for all scanning energies considered in this study. Findings in the present study also show that the scanning pattern affects the residual stress and deformation more than does the scanning energy. Full article

(This article belongs to the Special Issue The Additive Manufacturing of Metallic Alloys)

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9 pages, 2005 KiB

Open AccessArticle

Effect of the Addition of Re on the Microstructure and Phase Composition of Haynes 282: Ab Initio Modelling and Experimental Investigation of Additively Manufactured Specimens

by Antoni Wadowski, Jan S. Wróbel, Milena Koralnik and Ryszard Sitek

Materials 2023, 16(12), 4419; https://doi.org/10.3390/ma16124419 - 15 Jun 2023

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Abstract

Interactions in a multicomponent Ni-Cr-Mo-Al-Re model alloy were determined by ab initio calculations in order to investigate the Re doping effect on Haynes 282 alloys. Simulation results provided an understanding of short-range interactions in the alloy and successfully predicted the formation of a [...] Read more.

Interactions in a multicomponent Ni-Cr-Mo-Al-Re model alloy were determined by ab initio calculations in order to investigate the Re doping effect on Haynes 282 alloys. Simulation results provided an understanding of short-range interactions in the alloy and successfully predicted the formation of a Cr and Re-rich phase. The Haynes 282 + 3 wt% Re alloy was manufactured using the additive manufacturing direct metal laser sintering (DMLS) technique, in which the presence of the (Cr₁₇Re₆)C₆ carbide was confirmed by an XRD study. The results provide useful information about the interactions between Ni, Cr, Mo, Al, and Re as a function of temperature. The designed five-element model can lead to a better understanding of phenomena that occur during the manufacture or heat treatment of modern, complex, multicomponent Ni-based superalloys. Full article

(This article belongs to the Special Issue The Additive Manufacturing of Metallic Alloys)

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13 pages, 5973 KiB

Open AccessArticle

Heat Treatment Optimization for a High Strength Al–Mn–Sc Alloy Fabricated by Selective Laser Melting

by Hongyu Liu, Hao Zhang, Liju Meng, Yulong Li and Sheng Cao

Materials 2023, 16(11), 4054; https://doi.org/10.3390/ma16114054 - 29 May 2023

Cited by 2 | Viewed by 1221

Abstract

A selective laser-melted Al–Mn–Sc alloy with 99.9% relative density has been obtained in this work through systematic process optimization. The as-fabricated specimen had the lowest hardness and strength, but the highest ductility. The aging response has shown that 300 °C/5 h is the [...] Read more.

A selective laser-melted Al–Mn–Sc alloy with 99.9% relative density has been obtained in this work through systematic process optimization. The as-fabricated specimen had the lowest hardness and strength, but the highest ductility. The aging response has shown that 300 °C/5 h is the peak aged condition, and it had the highest hardness, yield strength, ultimate tensile strength, and elongation at fracture. Such a high strength was attributed to the uniformly distributed nano-sized secondary Al₃Sc precipitates. A further increase in aging temperature to 400 °C resulted in an over-aged condition, which contained a reduced volume fraction of secondary Al₃Sc precipitates and resulted in a reduced strength. Full article

(This article belongs to the Special Issue The Additive Manufacturing of Metallic Alloys)

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19 pages, 26809 KiB

Open AccessArticle

Selective Laser Melting Additive Manufactured Tantalum: Effect of Microstructure and Impurities on the Strengthening-Toughing Mechanism

by Fengjun Lian, Longqing Chen, Changgui Wu, Zhuang Zhao, Jingang Tang and Jun Zhu

Materials 2023, 16(8), 3161; https://doi.org/10.3390/ma16083161 - 17 Apr 2023

Cited by 1 | Viewed by 1200

Abstract

The balance between the strength and the toughness of pure tantalum (Ta) fabricated with selective laser melting (SLM) additive manufacturing is a major challenge due to the defect generation and affinity for oxygen and nitrogen. This study investigated the effects of energy density [...] Read more.

The balance between the strength and the toughness of pure tantalum (Ta) fabricated with selective laser melting (SLM) additive manufacturing is a major challenge due to the defect generation and affinity for oxygen and nitrogen. This study investigated the effects of energy density and post-vacuum annealing on the relative density and microstructure of SLMed tantalum. The influences of microstructure and impurities on strength and toughness were mainly analyzed. The results indicated that the toughness of SLMed tantalum significantly increased due to a reduction in pore defects and oxygen-nitrogen impurities, with energy density decreasing from 342 J/mm³ to 190 J/mm³. The oxygen impurities mainly stemmed from the gas inclusions of tantalum powders, while nitrogen impurities were mainly from the chemical reaction between the molten liquid tantalum and nitrogen in the atmosphere. The proportion of <110> texture decreased after vacuum-annealing at 1200 °C, while that of the <100> texture increased. Concurrently, the density of dislocations and small-angle grain boundaries significantly decreased while the resistance of the deformation dislocation slip was significantly reduced, enhancing the fractured elongation up to 28% at the expense of 14% tensile strength. Full article

(This article belongs to the Special Issue The Additive Manufacturing of Metallic Alloys)

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13 pages, 16982 KiB

Open AccessArticle

Nitriding Behaviour and Microstructure of High-Nitrogen Stainless Steel during Selective Laser Melting

by Xin Sun, Jianbiao Ren, Yachao Wang, Dingguo Zhao, Shuhuan Wang, Xiaojing Xiong and Jeremy Heng Rao

Materials 2023, 16(6), 2505; https://doi.org/10.3390/ma16062505 - 21 Mar 2023

Cited by 2 | Viewed by 1309

Abstract

High-nitrogen stainless steels are widely used due to their excellent comprehensive performance. In this study, the effects of process parameters (laser power, scanning speed, and cavity pressure) on the formation of high-nitrogen stainless steels were studied by using conventional selective laser melting and [...] Read more.

High-nitrogen stainless steels are widely used due to their excellent comprehensive performance. In this study, the effects of process parameters (laser power, scanning speed, and cavity pressure) on the formation of high-nitrogen stainless steels were studied by using conventional selective laser melting and high-pressure selective laser melting (HPSLM). The nitrogen content, nitrogen emission, phase composition, microstructure, and microhardness of the high-nitrogen stainless steel samples obtained through selective laser melting (SLM) were analysed by using an oxygen/nitrogen/hydrogen analyser, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and electron backscatter diffraction. The results showed that the maximum nitrogen emission in the SLM sample was 0.175 wt.%, the emission rate reached up to 54.7%, and the maximum nitrogen content in the HPSLM sample was 1.07 wt.%. There was no significant difference between the phase peak positions of the SLM samples with different laser powers and the original powder. The main phase of the HPSLM sample changed at 0.3 MPa (from α-Fe to γ-Fe phase); the microstructure of the SLM sample was mainly composed of columnar and cellular crystals, and columnar crystal bands formed along the direction of heat flow. The HPSLM sample was mainly composed of equiaxed crystals with a grain size of 10–15 μm. At an energy density of 136 J/mm³, the microhardness and relative density reached their peak values of 409 HV and 98.85%, respectively. Full article

(This article belongs to the Special Issue The Additive Manufacturing of Metallic Alloys)

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