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Design and Post Processing for Metal Additive Manufacturing

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Manufacturing Processes and Systems".

Deadline for manuscript submissions: closed (10 October 2023) | Viewed by 28332

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Special Issue Editors

Dr. Bartłomiej Wysocki

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Guest Editor

Multidisciplinary Research Center, Cardinal Stefan Wyszynski University in Warsaw, Warsaw, Poland
Interests: additive manufacturing; titanium alloys; chemical polishing; cellular structures; implants; bioengineering; AI/ML
Special Issues, Collections and Topics in MDPI journals

Prof. Joseph Buhagiar

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Guest Editor

Department of Metallurgy & Materials Engineering, Faculty of Engineering, University of Malta, MSD 2080 Msida, Malta
Interests: additive manufacturing; surface engineering; biomaterials; medical implants; corrosion science; biodegradable metals

Dr. Tomasz Durejko

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Guest Editor

Department of Materials Technology, Faculty of Advanced Technologies and Chemistry, Military University of Technology, 00-908 Warsaw, Poland
Interests: additive manufacturing (FDM, HT-FDM, SLA, SLM, LENS); titanium hip implants; superalloys, functional graded materials and composites; powder metallurgy; CNC machining

Special Issue Information

Dear Colleagues,

Additive manufacturing (AM) of metals has been receiving particular attention because functional, net shape parts in various industrial sectors can now be fabricated using laser, electron beam or binder jetting methods. Furthermore, recent advances in additive manufacturing (AM) techniques offer many opportunities in terms of design freedom. Complex geometries like cellular solids, metamaterials or biomimetic materials that could not be easily manufactured using conventional techniques are now relatively easy to be manufactured using AM. Today, these objects can be fabricated from elemental or alloyed metallic powders, based on the computer-aided design (CAD) models. This Special Issue is open to submissions concerning, but not limited to, design of elements with predicted microstructure and mechanical properties, artificial intelligence/machine learning (AI/ML) in AM, numerical algorithms for AM and µ-CT imagining for quality control. Despite the fact that AM manufacturing in a powder bed provides a possibility to fabricate objects of any shape in one production step, it also carries some disadvantages. One drawback is the requirement to generate support for the fabricated parts. Such support should dissipate the heat generated during 3D printing process from metallic powders and minimize geometrical distortions induced by internal stresses. The computer simulations and improved fabrication protocols that decrease these issues will be covered in this Special Issue. During the AM processes, not all particles are melted and, therefore, the removal of any unmelted particles needs to be performed with mechanical or chemical post-processing methods. This Special Issue is, therefore, dedicated to the various areas of research relevant to metal AM. The processing parameters and post-processing methods not limited to annealing and chemical modifications are of interest. Finally, the design of materials dedicated to metal AM and description of modifications to commercial machines are also welcome in the submissions.

Dr. Bartłomiej Wysocki
Prof. Joseph Buhagiar
Dr. Tomasz Durejko
Guest Editors

Manuscript Submission Information

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Keywords

additive manufacturing / 3D printing
powder bed fusion (PBF)
laser metal deposition (LMD)
design approaches and process simulations
am post-processing
new materials, metal additive manufacturing processes and systems
artificial intelligence and machine learning (AI/ML) in AM
standardization and quality control in metal additive manufacturing

Published Papers (14 papers)

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Research

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18 pages, 30253 KiB

Open AccessArticle

Al–Al₃Ni In Situ Composite Formation by Wire-Feed Electron-Beam Additive Manufacturing

by Artem Dobrovolskii, Andrey Chumaevskii, Anna Zykova, Nikolay Savchenko, Denis Gurianov, Aleksandra Nikolaeva, Natalia Semenchuk, Sergey Nikonov, Pavel Sokolov, Valery Rubtsov and Evgeny Kolubaev

Materials 2023, 16(11), 4157; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16114157 - 02 Jun 2023

Viewed by 1126

Abstract

The regularities of microstructure formation in samples of multiphase composites obtained by additive electron beam manufacturing on the basis of aluminum alloy ER4043 and nickel superalloy Udimet-500 have been studied. The results of the structure study show that a multicomponent structure is formed in the samples with the presence of Cr₂₃C₆ carbides, solid solutions based on aluminum -Al or silicon -Si, eutectics along the boundaries of dendrites, intermetallic phases Al₃Ni, AlNi₃, Al₇5Co₂₂Ni₃, and Al₅Co, as well as carbides of complex composition AlCCr, Al₈SiC₇, of a different morphology. The formation of a number of intermetallic phases present in local areas of the samples was also distinguished. A large amount of solid phases leads to the formation of a material with high hardness and low ductility. The fracture of composite specimens under tension and compression is brittle, without revealing the stage of plastic flow. Tensile strength values are significantly reduced from the initial 142–164 MPa to 55–123 MPa. In compression, the tensile strength values increase to 490–570 MPa and 905–1200 MPa with the introduction of 5% and 10% nickel superalloy, respectively. An increase in the hardness and compressive strength of the surface layers results in an increase in the wear resistance of the specimens and a decrease in the coefficient of friction. Full article

(This article belongs to the Special Issue Design and Post Processing for Metal Additive Manufacturing)

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15 pages, 5942 KiB

Open AccessArticle

Influence of Different Build Orientations and Heat Treatments on the Creep Properties of Inconel 718 Produced by PBF-LB

by Anke Kaletsch, Siyuan Qin and Christoph Broeckmann

Materials 2023, 16(11), 4087; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16114087 - 31 May 2023

Cited by 2 | Viewed by 1361

Abstract

Inconel 718 is a nickel-based superalloy with excellent creep properties and good tensile and fatigue strength. In the field of additive manufacturing, it is a versatile and widely used alloy due to its good processability in the powder bed fusion with laser beam (PBF-LB) process. The microstructure and mechanical properties of the alloy produced by PBF-LB have already been studied in detail. However, there are fewer studies on the creep resistance of additively manufactured Inconel 718, especially when the focus is on the build direction dependence and post-treatment by hot isostatic pressing (HIP). Creep resistance is a crucial mechanical property for high-temperature applications. In this study, the creep behavior of additively manufactured Inconel 718 was investigated in different build orientations and after two different heat treatments. The two heat treatment conditions are, first, solution annealing at 980 °C followed by aging and, second, HIP with rapid cooling followed by aging. The creep tests were performed at 760 °C and at four different stress levels between 130 MPa and 250 MPa. A slight influence of the build direction on the creep properties was detected, but a more significant influence was shown for the different heat treatments. The specimens after HIP heat treatment show much better creep resistance than the specimens subjected to solution annealing at 980 °C with subsequent aging. Full article

(This article belongs to the Special Issue Design and Post Processing for Metal Additive Manufacturing)

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23 pages, 5783 KiB

Open AccessArticle

The Effect of a Duplex Surface Treatment on the Corrosion and Tribocorrosion Characteristics of Additively Manufactured Ti-6Al-4V

by Kelsey Ann Vella, Joseph Buhagiar, Glenn Cassar, Martina Marie Pizzuto, Luana Bonnici, Jian Chen, Xiyu Zhang, Zhiquan Huang and Ann Zammit

Materials 2023, 16(5), 2098; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16052098 - 04 Mar 2023

Cited by 7 | Viewed by 1718

Abstract

The use of additively manufactured components specifically utilizing titanium alloys has seen rapid growth particularly in aerospace applications; however, the propensity for retained porosity, high(er) roughness finish, and detrimental tensile surface residual stresses are still a limiting factor curbing its expansion to other sectors such as maritime. The main aim of this investigation is to determine the effect of a duplex treatment, consisting of shot peening (SP) and a coating deposited by physical vapor deposition (PVD), to mitigate these issues and improve the surface characteristics of this material. In this study, the additive manufactured Ti-6Al-4V material was observed to have a tensile and yield strength comparable to its wrought counterpart. It also exhibited good impact performance undergoing mixed mode fracture. It was also observed that the SP and duplex treatments resulted in a 13% and 210% increase in hardness, respectively. Whilst the untreated and SP treated samples exhibited a similar tribocorrosion behavior, the duplex-treated sample exhibited the greatest resistance to corrosion-wear observed by the lack of damage on the surface and the diminished material loss rates. On the other hand, the surface treatments did not improve the corrosion performance of the Ti-6Al-4V substrate. Full article

(This article belongs to the Special Issue Design and Post Processing for Metal Additive Manufacturing)

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21 pages, 9328 KiB

Open AccessArticle

Additively Manufactured 316L Stainless Steel Subjected to a Duplex Peening-PVD Coating Treatment

by Luana Bonnici, Joseph Buhagiar, Glenn Cassar, Kelsey Ann Vella, Jian Chen, Xiyu Zhang, Zhiquan Huang and Ann Zammit

Materials 2023, 16(2), 663; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16020663 - 10 Jan 2023

Cited by 3 | Viewed by 1470

Abstract

This research studies the individual and combined effects of mechanical shot peening and the deposition of TiAlCuN coating on additively manufactured 316L stainless steel. Shot peening has been found to induce a 40% increase in surface hardness, while the combined effect of shot peening and the coating produced an approximately three-fold increase in surface hardness when compared to the as-printed coupons. Shot peening reduced the surface roughness of printed metal coupons by 50%, showing that shot peening can also serve to improve the surface finish of as-printed 316L stainless steel components. The peening process was found to induce a compressive residual stress of 589 MPa, with a maximum affected depth of approximately 200 μm. Scratch testing of the printed and coated specimens showed complete delamination failure at a normal load of 14 N, when compared to hybrid treated samples which failed at 10 N. On the other hand, from the corrosion tests, it was found that the hybrid treated samples provided the optimal results as opposed to the other variables. Full article

(This article belongs to the Special Issue Design and Post Processing for Metal Additive Manufacturing)

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11 pages, 4274 KiB

Open AccessArticle

Analysis of the Effect of Machining of the Surfaces of WAAM 18Ni 250 Maraging Steel Specimens on Their Durability

by Daren Peng, Andrew S. M. Ang, Alex Michelson, Victor Champagne, Aaron Birt and Rhys Jones

Materials 2022, 15(24), 8890; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15248890 - 13 Dec 2022

Cited by 2 | Viewed by 1026

Abstract

It is now well-known that the interaction between surface roughness and surface-breaking defects can significantly degrade the fatigue life of additively manufactured (AM) parts. This is also aptly illustrated in the author’s recent study on the durability of wire and arc additively manufactured (WAAM) 18Ni 250 Maraging steel specimens, where it was reported that failure occurred due to fatigue crack growth that arose due to the interaction between the surface roughness and surface-breaking material defects. To improve the durability of an AM part, several papers have suggested the machining of rough surfaces. However, for complex geometries the fully machining of the entire rough surface is not always possible and the effect of the partial machining on durability is unknown. Therefore, this paper investigates if partial machining of WAAM 18Ni 250 Maraging steel surfaces will help to improve the durability of these specimens. Unfortunately, the result of this investigation has shown that partial machining may not significantly improve durability of WAAM 18Ni 250 Maraging steel specimens. Due to the order of surface roughness seen in WAAM 250 Maraging steel, the improvement to durability is only realized by full machining to completely remove the remnants of any print artefacts. Full article

(This article belongs to the Special Issue Design and Post Processing for Metal Additive Manufacturing)

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14 pages, 5764 KiB

Open AccessArticle

Quality Quantification and Control via Novel Self-Growing Process-Quality Model of Parts Fabricated by LPBF Process

by Xinyi Xiao, Beibei Chu and Zhengyan Zhang

Materials 2022, 15(23), 8520; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15238520 - 29 Nov 2022

Cited by 3 | Viewed by 1297

Abstract

Laser Powder Bed Fusion (LPBF) presents a more extensive allowable design complexity and manufacturability compared with the traditional manufacturing processes by depositing materials in a layer-wised manner. However, the process variability in the LPBF process induces quality uncertainty and inconsistency. Specifically, the mechanical properties, e.g., tensile strength, are hard to be predicted and controlled in the LPBF process. Much research has recently been reported exploring the qualitative influence of single/two process parameters on tensile strength. In fact, mechanical properties are comprehensively affected by multiple correlated process parameters with unclear and complex interactions. Thus, the study on the quantitative process-quality model of the metal LPBF process is urgently needed to provide an enough-strength component via the metal LPBF process. Recent progress in artificial intelligence (AI) and machine learning (ML) provides new insight into quality prediction in terms of computational accuracy and speed. However, the predictive model quality through the traditional AL/ML is heavily determined by the training data size, and the experimental analysis can be expansive on LPBF. This paper explores the comprehensive effect of the tensile strength of 316L stainless-steel parts on LPBF and proposes a valid quantitative predictive model through a novel self-growing machine-learning framework. The self-growing framework can autonomously expand and classify the growing dataset to provide a high-accuracy prediction with fewer input data. To verify this predictive model of tensile strength, specimens manufactured by the LPBF process with different group process parameters (laser power, scanning speed, and hatch spacing) are collected. The experimental results validate the predicted tensile strengths within a less than 3% deviation. Full article

(This article belongs to the Special Issue Design and Post Processing for Metal Additive Manufacturing)

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14 pages, 6385 KiB

Open AccessArticle

Surface Morphology, Compressive Behavior, and Energy Absorption of Graded Triply Periodic Minimal Surface 316L Steel Cellular Structures Fabricated by Laser Powder Bed Fusion

by Bharath Bhushan Ravichander, Shweta Hanmant Jagdale and Golden Kumar

Materials 2022, 15(23), 8294; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15238294 - 22 Nov 2022

Cited by 4 | Viewed by 1623

Abstract

Laser powder bed fusion (LPBF) is an emerging technique for the fabrication of triply periodic minimal surface (TPMS) structures in metals. In this work, different TPMS structures such as Diamond, Gyroid, Primitive, Neovius, and Fisher–Koch S with graded relative densities are fabricated from 316L steel using LPBF. The graded TPMS samples are subjected to sandblasting to improve the surface finish before mechanical testing. Quasi-static compression tests are performed to study the deformation behavior and energy absorption capacity of TPMS structures. The results reveal superior stiffness and energy absorption capabilities for the graded TPMS samples compared to the uniform TPMS structures. The Fisher–Koch S and Primitive samples show higher strength whereas the Fisher–Koch S and Neovius samples exhibit higher elastic modulus. The Neovius type structure shows the highest energy absorption up to 50% strain among all the TPMS structures. The Gibson–Ashby coefficients are calculated for the TPMS structures, and it is found that the C₂ values are in the range suggested by Gibson and Ashby while C₁ values differ from the proposed range. Full article

(This article belongs to the Special Issue Design and Post Processing for Metal Additive Manufacturing)

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17 pages, 7851 KiB

Open AccessArticle

Design and Fabrication of an Additively Manufactured Aluminum Mirror with Compound Surfaces

by Jizhen Zhang, Chao Wang, Hemeng Qu, Haijun Guan, Ha Wang, Xin Zhang, Xiaolin Xie, He Wang, Kai Zhang and Lijun Li

Materials 2022, 15(20), 7050; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15207050 - 11 Oct 2022

Cited by 3 | Viewed by 1489

Abstract

Microsatellites have a great attraction to researchers due to their high reliability, resource utilization, low cost, and compact size. As the core component of the optical payload, the mirror directly affects the system package size. Therefore, the structural design of mirrors is critical in the compact internal space of microsatellites. This study proposes a closed-back mirror with composite surfaces based on additive manufacturing (AM). Compared with the open-back mirror, it provides excellent optomechanical performance. In addition, AM significantly reduces the intricate mechanical parts’ manufacturing difficulty. Finally, the roughness was better than 2 nm. The surface shape of the AM aluminum mirror reached RMS 1/10λ (λ = 632.8 nm) with the aid of ultra-precision machining technologies such as single-point diamond turning (SPDT), surface modification, and polishing, and the maximum deviation of the surface shape was about RMS 1/42λ (λ = 632.8 nm) after the thermal cycle test, which verified the optical grade application of AM. Full article

(This article belongs to the Special Issue Design and Post Processing for Metal Additive Manufacturing)

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23 pages, 14952 KiB

Open AccessArticle

Laser Powder Bed Fusion Process Parameters’ Optimization for Fabrication of Dense IN 625

by Alexandru Paraschiv, Gheorghe Matache, Mihaela Raluca Condruz, Tiberius Florian Frigioescu and Laurent Pambaguian

Materials 2022, 15(16), 5777; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15165777 - 21 Aug 2022

Cited by 6 | Viewed by 1783

Abstract

This paper presents an experimental study on the influence of the main Laser Powder Bed Fusion (PBF-LB) process parameters on the density and surface quality of the IN 625 superalloy manufactured using the Lasertec 30 SLM machine. Parameters’ influence was investigated within a workspace defined by the laser power (150–400 W), scanning speed (500–900 m/s), scanning strategy (90° and 67°), layer thickness (30–70 µm), and hatch distance (0.09–0.12 µm). Experimental results showed that laser power and scanning speed play a determining role in producing a relative density higher than 99.5% of the material’s theoretical density. A basic set of process parameters was selected for generating high-density material: laser power 250 W, laser speed 750 mm/s, layer thickness 40 µm, and hatch distance 0.11 mm. The 67° scanning strategy ensures higher roughness surfaces than the 90° scanning strategy, roughness that increases as the laser power increases and the laser speed decreases. Full article

(This article belongs to the Special Issue Design and Post Processing for Metal Additive Manufacturing)

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15 pages, 5056 KiB

Open AccessArticle

Heat Treatment of NiTi Alloys Fabricated Using Laser Powder Bed Fusion (LPBF) from Elementally Blended Powders

by Agnieszka Chmielewska, Bartłomiej Wysocki, Piotr Kwaśniak, Mirosław Jakub Kruszewski, Bartosz Michalski, Aleksandra Zielińska, Bogusława Adamczyk-Cieślak, Agnieszka Krawczyńska, Joseph Buhagiar and Wojciech Święszkowski

Materials 2022, 15(9), 3304; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15093304 - 05 May 2022

Cited by 11 | Viewed by 2318

Abstract

The use of elemental metallic powders and in situ alloying in additive manufacturing (AM) is of industrial relevance as it offers the required flexibility to tailor the batch powder composition. This solution has been applied to the AM manufacturing of nickel-titanium (NiTi) shape memory alloy components. In this work, we show that laser powder bed fusion (LPBF) can be used to create a Ni_55.7Ti_44.3 alloyed component, but that the chemical composition of the build has a large heterogeneity. To solve this problem three different annealing heat treatments were designed, and the resulting porosity, microstructural homogeneity, and phase formation was investigated. The heat treatments were found to improve the alloy’s chemical and phase homogeneity, but the brittle NiTi₂ phase was found to be stabilized by the 0.54 wt.% of oxygen present in all fabricated samples. As a consequence, a Ni₂Ti₄O phase was formed and was confirmed by transmission electron microscopy (TEM) observation. This study showed that pore formation in in situ alloyed NiTi can be controlled via heat treatment. Moreover, we have shown that the two-step heat treatment is a promising method to homogenise the chemical and phase composition of in situ alloyed NiTi powder fabricated by LPBF. Full article

(This article belongs to the Special Issue Design and Post Processing for Metal Additive Manufacturing)

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15 pages, 4658 KiB

Open AccessArticle

Nanofunctionalization of Additively Manufactured Titanium Substrates for Surface-Enhanced Raman Spectroscopy Measurements

by Marcin Pisarek, Robert Ambroziak, Marcin Hołdyński, Agata Roguska, Anna Majchrowicz, Bartłomiej Wysocki and Andrzej Kudelski

Materials 2022, 15(9), 3108; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15093108 - 25 Apr 2022

Cited by 3 | Viewed by 1874

Abstract

Powder bed fusion using a laser beam (PBF-LB) is a commonly used additive manufacturing (3D printing) process for the fabrication of various parts from pure metals and their alloys. This work shows for the first time the possibility of using PBF-LB technology for the production of 3D titanium substrates (Ti 3D) for surface-enhanced Raman scattering (SERS) measurements. Thanks to the specific development of the 3D titanium surface and its nanoscale modification by the formation of TiO₂ nanotubes with a diameter of ~80 nm by the anodic oxidation process, very efficient SERS substrates were obtained after deposition of silver nanoparticles (0.02 mg/cm², magnetron sputtering). The average SERS enhancement factor equal to 1.26 × 10⁶ was determined for pyridine (0.05 M + 0.1 M KCl), as a model adsorbate. The estimated enhancement factor is comparable with the data in the literature, and the substrate produced in this way is characterized by the high stability and repeatability of SERS measurements. The combination of the use of a printed metal substrate with nanofunctionalization opens a new path in the design of SERS substrates for applications in analytical chemistry. Methods such as SEM scanning microscopy, photoelectron spectroscopy (XPS) and X-ray diffraction analysis (XRD) were used to determine the morphology, structure and chemical composition of the fabricated materials. Full article

(This article belongs to the Special Issue Design and Post Processing for Metal Additive Manufacturing)

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23 pages, 44249 KiB

Open AccessArticle

Design Rules for Hybrid Additive Manufacturing Combining Selective Laser Melting and Micromilling

by David Sommer, Babette Götzendorfer, Cemal Esen and Ralf Hellmann

Materials 2021, 14(19), 5753; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14195753 - 02 Oct 2021

Cited by 12 | Viewed by 2714

Abstract

We report on a comprehensive study to evaluate fundamental properties of a hybrid manufacturing approach, combining selective laser melting and high speed milling, and to characterize typical geometrical features and conclude on a catalogue of design rules. As for any additive manufacturing approach, the understanding of the machine properties and the process behaviour as well as such a selection guide is of upmost importance to foster the implementation of new machining concepts and support design engineers. Geometrical accuracy between digitally designed and physically realized parts made of maraging steel and dimensional limits are analyzed by stripe line projection. In particular, we identify design rules for numerous basic geometric elements like walls, cylinders, angles, inclinations, overhangs, notches, inner and outer radii of spheres, chamfers in build direction, and holes of different shape, respectively, as being manufactured by the hybrid approach and compare them to sole selective laser melting. While the cutting tool defines the manufacturability of, e.g., edges and corners, the milling itself improves the surface roughness to Ra < 2

μ

m. Thus, the given advantages of this hybrid process, e.g., space-resolved and custom-designed roughness and the superior geometrical accuracy are evaluated. Finally, we exemplify the potential of this particular promising hybrid approach by demonstrating an injection mold with a conformal cooling for a charge socket for an electro mobile. Full article

(This article belongs to the Special Issue Design and Post Processing for Metal Additive Manufacturing)

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Review

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34 pages, 11853 KiB

Open AccessReview

The State of the Art in Machining Additively Manufactured Titanium Alloy Ti-6Al-4V

by Chen Zhang, Dongyi Zou, Maciej Mazur, John P. T. Mo, Guangxian Li and Songlin Ding

Materials 2023, 16(7), 2583; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16072583 - 24 Mar 2023

Cited by 7 | Viewed by 2805

Abstract

Titanium alloys are extensively used in various industries due to their excellent corrosion resistance and outstanding mechanical properties. However, titanium alloys are difficult to machine due to their low thermal conductivity and high chemical reactivity with tool materials. In recent years, there has been increasing interest in the use of titanium components produced by additive manufacturing (AM) for a range of high-value applications in aerospace, biomedical, and automotive industries. The machining of additively manufactured titanium alloys presents additional machining challenges as the alloys exhibit unique properties compared to their wrought counterparts, including increased anisotropy, strength, and hardness. The associated higher cutting forces, higher temperatures, accelerated tool wear, and decreased machinability lead to an expensive and unsustainable machining process. The challenges in machining additively manufactured titanium alloys are not comprehensively documented in the literature, and this paper aims to address this limitation. A review is presented on the machining characteristics of titanium alloys produced by different AM techniques, focusing on the effects of anisotropy, porosity, and post-processing treatment of additively manufactured Ti-6Al-4V, the most commonly used AM titanium alloy. The mechanisms resulting in different machining performance and quality are analysed, including the influence of a hybrid manufacturing approach combining AM with conventional methods. Based on the review of the latest developments, a future outlook for machining additively manufactured titanium alloys is presented. Full article

(This article belongs to the Special Issue Design and Post Processing for Metal Additive Manufacturing)

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20 pages, 2205 KiB

Open AccessReview

Wire Arc Additive Manufacturing (WAAM) for Aluminum-Lithium Alloys: A Review

by Paula Rodríguez-González, Elisa María Ruiz-Navas and Elena Gordo

Materials 2023, 16(4), 1375; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16041375 - 06 Feb 2023

Cited by 8 | Viewed by 3883

Abstract

Out of all the metal additive manufacturing (AM) techniques, the directed energy deposition (DED) technique, and particularly the wire-based one, are of great interest due to their rapid production. In addition, they are recognized as being the fastest technique capable of producing fully functional structural parts, near-net-shape products with complex geometry and almost unlimited size. There are several wire-based systems, such as plasma arc welding and laser melting deposition, depending on the heat source. The main drawback is the lack of commercially available wire; for instance, the absence of high-strength aluminum alloy wires. Therefore, this review covers conventional and innovative processes of wire production and includes a summary of the Al-Cu-Li alloys with the most industrial interest in order to foment and promote the selection of the most suitable wire compositions. The role of each alloying element is key for specific wire design in WAAM; this review describes the role of each element (typically strengthening by age hardening, solid solution and grain size reduction) with special attention to lithium. At the same time, the defects in the WAAM part limit its applicability. For this reason, all the defects related to the WAAM process, together with those related to the chemical composition of the alloy, are mentioned. Finally, future developments are summarized, encompassing the most suitable techniques for Al-Cu-Li alloys, such as PMC (pulse multicontrol) and CMT (cold metal transfer). Full article

(This article belongs to the Special Issue Design and Post Processing for Metal Additive Manufacturing)

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