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AM-PBF Processes and Joining Similar/Dissimilar PBF Materials: Quo Vadis?

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A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Additive Manufacturing".

Deadline for manuscript submissions: closed (31 March 2021) | Viewed by 24624

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Special Issue Editor

Prof. Dr. Adin Stern

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Guest Editor

Department of Materials Engineering, Ben-Gurion University of the Negev, Beer Sheba, Israel
Interests: additive manufacturing processes (PBF and FDM); welding and joining processes (SSW-MPW and SPS, GTAW); archeometallurgical research on metallurgy and joining of metals; additive manufacturing standards and standardization

Special Issue Information

Dear Colleagues,

This Special Issue is dedicated to the publication of research papers and reviews that focus on the applications of powder bed fusion technologies, to illustrate recent advances in the field. AM-PBF processes are currently providing novel approaches to control the topological structures, microstructures, and mechanical properties of components that are integrated into numerous industrial applications. The currently used PBF processes are selective laser melting, and electron-beam melting technologies producing net shapes of relatively small complex parts. The size of fabricated components by LPBF and EBM technologies are limited by the build envelopes. Due to the size limit of the build envelopes, it is logical to consider that joining techniques may enable the production of large-scale components with complex features from LPBF and EBM parts. The necessity of large PBF parts makes the R&D of joining processes essential and contributes to the importance of the topic. This Special Issue covers new and modified processing and post-processing methods, structure and mechanical characterizations, theoretical computations, and industrial applications associated with AM-PBF techniques, including the production of large AM-PBF components by joining.

Topics of particular interest include, but are not limited to the following:

Advancements in LBBF and EBM processes;
Topological designs of metal products, including porous metals and metallic foams, applicable to PBF;
Production of new metallic powder grades tolerant to PBF methods;
Development of process parameters, build strategies, and microstructural control of PBF-produced metallic components;
Properties and performance of PBF-produced metallic alloys (e.g. mechanical, thermal, electrical, and chemical (corrosion));
Theoretical computations to further understand phenomena related to BPF processing;

Fusion and Solid-state joining of PBF components;
Fusion and Solid-state joining of PBF to wrought components;
Hybrid joining of PBF components.

Combining publications in the form of short communications, full-length articles, and reviews from the above-mentioned areas will permit us to issue a high-impact journal. Please note that Metals is an open-access journal, and this Special Issue will be freely available for all readers across the globe.

Prof. Dr. Adin Stern
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

SLM, SLS, and EBAM/EBM processes
metal powders tolerant to AM-PBF
design
microstructure–properties relationship
properties, discontinuities, and performance characterization
thermal and mechanical modelling
manufacturing
industrial applications

Published Papers (6 papers)

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Research

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11 pages, 8239 KiB

Open AccessArticle

Microstructure and Magnetic Properties of Selected Laser Melted Ni-Mn-Ga and Ni-Mn-Ga-Fe Powders Derived from as Melt-Spun Ribbons Precursors

by Wojciech Maziarz, Paweł Czaja, Robert Chulist, Anna Wójcik, Łukasz Żrodowski, Bartosz Morończyk, Rafał Wróblewski and Maciej Kowalczyk

Metals 2021, 11(6), 903; https://doi.org/10.3390/met11060903 - 31 May 2021

Cited by 9 | Viewed by 2449

Abstract

Selective Laser Melting was successfully used as a fabrication method to produce Ni-Mn-Ga and Ni-Mn-Ga-Fe ferromagnetic shape memory alloys. The starting material in a powder form with an average particle size of about 17.6 µm was produced by milling of as melt-spun ribbons. The microstructure, phase composition, and martensitic transformation behavior of both powder precursors and laser melted alloys were investigated by several methods, including high energy X-ray diffraction, electron microscopy, and vibrating sample magnetometry. The as laser melted materials are chemically homogenous and show a typical layered microstructure. Both alloy compositions have a duplex structure consisting either of austenite and 10M martensite (Ni-Mn-Ga) or a mixture of 14M and NM martensitic phases (Ni-Mn-Ga-Fe), contrary to the as milled powder precursors showing fcc structure in both cases. The forward martensitic transformation takes place at 336 and 325 K for Ni-Mn-Ga and Ni-Mn-Ga-Fe, respectively, while the magnetic response is much stronger for Ni-Mn-Ga than for the quaternary alloy. The results show that Selective Laser Melting allows for producing of good quality, homogenous materials. However, their microstructural features and consequently shape memory behavior should be tailored by additional heat treatment. Full article

(This article belongs to the Special Issue AM-PBF Processes and Joining Similar/Dissimilar PBF Materials: Quo Vadis?)

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15 pages, 5112 KiB

Open AccessFeature PaperArticle

Laser Defocusing Effect on the Microstructure and Defects of 17-4PH Parts Additively Manufactured by SLM at a Low Energy Input

by Paola Leo, Marcello Cabibbo, Antonio Del Prete, Sara Giganto, Susana Martínez-Pellitero and Joaquin Barreiro

Metals 2021, 11(4), 588; https://doi.org/10.3390/met11040588 - 03 Apr 2021

Cited by 14 | Viewed by 2745

Abstract

In this paper, the microstructure, defects, hardness, and tensile strength of the 17-4PH specimens manufactured additively using the selective laser melting (SLM) technique were studied. The analyzed parts (10 mm size cubic specimens and tensile specimens) were manufactured with different defocus parameter values (−1, 0, +1 mm) in order to evaluate this effect with a low power laser (38 W). The study was carried out on three different sections of each cubic specimen, one perpendicular to the laser beam or SLM manufacturing direction (transversal section), and another two parallel to the laser beam direction (longitudinal sections). The specimens microstructures were analyzed with an X-ray diffraction technique, as well as optical, scanning electron, and transmission electron microscopes. Image J software was used to characterize the defects and phase ratio. In addition, hardness and tensile tests were performed according to the corresponding standards. The results show that the amount of austenitic phase and the average grain size varied with defocusing. The percentage of defective area was less than 0.25%. The analyzed defocus distance did not affect the number and average size of the defects. Adjusting the defocusing SLM parameter is important for manufacturing parts with good mechanical properties. Full article

(This article belongs to the Special Issue AM-PBF Processes and Joining Similar/Dissimilar PBF Materials: Quo Vadis?)

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20 pages, 9643 KiB

Open AccessFeature PaperArticle

On Additive Manufactured AlSi10Mg to Wrought AA6060-T6: Characterisation of Optimal- and High-Energy Magnetic Pulse Welding Conditions

by Moshe Nahmany, Victor Shribman, Shlomo Levi, Dana Ashkenazi and Adin Stern

Metals 2020, 10(9), 1235; https://doi.org/10.3390/met10091235 - 14 Sep 2020

Cited by 6 | Viewed by 2410

Abstract

This novel research aims to examine the macro and microstructural bonding region development during magnetic pulse welding (MPW) of dissimilar additive manufactured (AM) laser powder-bed fusion (L-PBF) AlSi10Mg rod and AA6060-T6 wrought tube, using both optimal- and high-energy welding conditions. For that purpose, various joint characterisation methods were applied. It is demonstrated that high-quality hermetic welds are achievable with adjusted MPW process parameters. The macroscale analysis has shown that the joint interfaces are deformed to a waveform shape; the interface is starting relatively planar, with waves forming and growing in the welding direction. The observed thickening of the flyer’s wall after welding is the result of its diametral inward deformation, taking place during the process. A slight increase in microhardness was adjacent to the faying interfaces; a higher increase was measured on the AlSi10Mg material side, while a smaller one was observed on the AA6060 side. Along the wavy interfaces, resolidified “pockets” of material or occasionally discontinuous short layers exhibiting different morphologies, were detected. The jet residues are typically located towards the end of the weld, confirming a temperature rise that exceeds the melting temperature of both alloys. Far from the weld zone, extremely thin-film deposits were clearly observed on the inner flyer surfaces. The formation of isolated Si particles and thin-film deposits may point out that the local increase in temperatures leads to melting or even evaporation vaporisation of superficial layers from the colliding parts. It is worth noting that this type of jet residue was discovered for the first time in the present research. The current research work is expected to provide an understanding of weld formation mechanisms of additively manufactured parts to conventional wrought parts conforming to existing wrought/wrought weld knowledge. Full article

(This article belongs to the Special Issue AM-PBF Processes and Joining Similar/Dissimilar PBF Materials: Quo Vadis?)

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18 pages, 8223 KiB

Open AccessFeature PaperArticle

Gold–Silver Electroless Plating on Laser Powder-Bed Fusion Additively Printed AlSi10Mg Parts

by Alexandra Inberg, Dana Ashkenazi, Giora Kimmel, Yosi Shacham-Diamand and Adin Stern

Metals 2020, 10(5), 557; https://doi.org/10.3390/met10050557 - 26 Apr 2020

Cited by 10 | Viewed by 3802

Abstract

The current research presents a novel methodology for surface finishing of printed AlSi10Mg parts by electroless deposited gold–silver (electrum) alloys. The parts were printed by additive manufacturing laser powder-bed fusion (AM-LPBF). The electrum was chosen due to its appearance and good electrical and thermal properties and was deposited on disk-shaped specimens at 80 and 90 °C. The coating quality and appearance were studied by different methods for various deposition times and film thicknesses. The results indicate that Au–Ag coatings of AM-LPBF AlSi10Mg yield satisfactory results. The XRD analysis revealed that the coatings were composed of Au–Ag crystalline phases and beneath them, a quasi-amorphous or mixed quasi-amorphous and nanocrystalline Ni–P interlayer. The mechanism of electrum formation was studied based on the XPS analysis results as a function of the temperature and concentration. At 80 °C, the Ag was dominant at the beginning of the deposition process, while at 90 °C the Au was first detected on the interface. This result was explained by the electrochemical properties of alloying metals and the binding energies required to form metal–Ni and Au–Ag bonding. The results indicate that the electrum coatings are satisfactory, and the developed surface finishing process could be used for many applications. Full article

(This article belongs to the Special Issue AM-PBF Processes and Joining Similar/Dissimilar PBF Materials: Quo Vadis?)

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Review

Jump to: Research

15 pages, 3116 KiB

Open AccessReview

Progress of Flake Powder Metallurgy Research

by Behzad Sadeghi and Pasquale Cavaliere

Metals 2021, 11(6), 931; https://doi.org/10.3390/met11060931 - 08 Jun 2021

Cited by 20 | Viewed by 3986

Abstract

This paper reviewed several recent progresses of the new powder metallurgy technology known as flake powder metallurgy (FPM) including different processing routes, conventional FPM (C-FPM), slurry blending (SB), shift-speed ball milling (SSBM), and high-shear pre-dispersion and SSBM (HSPD/SSBM). The name of FPM was derived from the use of flake metal powders obtained by low-speed ball milling (LSBM) from spherical powder. In this case, the uniformity of reinforcement distribution leads to increased strength and ductility. Powder is the basic unit in PM, especially advanced PM, and its control is key to various new PM technologies. The FPM is a typical method for finely controlling the powder shape through low-energy ball milling (LEBM) to realize the preparation of advanced material structures. The present paper represents a review of the main results of research on FPM and indicates the potential for future studies devoted to the optimization of this processing route. Full article

(This article belongs to the Special Issue AM-PBF Processes and Joining Similar/Dissimilar PBF Materials: Quo Vadis?)

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25 pages, 10591 KiB

Open AccessReview

Laser Powder Bed Fusion of Precipitation-Hardened Martensitic Stainless Steels: A Review

by Le Zai, Chaoqun Zhang, Yiqiang Wang, Wei Guo, Daniel Wellmann, Xin Tong and Yingtao Tian

Metals 2020, 10(2), 255; https://doi.org/10.3390/met10020255 - 14 Feb 2020

Cited by 83 | Viewed by 8460

Abstract

Martensitic stainless steels are widely used in industries due to their high strength and good corrosion resistance performance. Precipitation-hardened (PH) martensitic stainless steels feature very high strength compared with other stainless steels, around 3-4 times the strength of austenitic stainless steels such as 304 and 316. However, the poor workability due to the high strength and hardness induced by precipitation hardening limits the extensive utilization of PH stainless steels as structural components of complex shapes. Laser powder bed fusion (L-PBF) is an attractive additive manufacturing technology, which not only exhibits the advantages of producing complex and precise parts with a short lead time, but also avoids or reduces the subsequent machining process. In this review, the microstructures of martensitic stainless steels in the as-built state, as well as the effects of process parameters, building atmosphere, and heat treatments on the microstructures, are reviewed. Then, the characteristics of defects in the as-built state and the causes are specifically analyzed. Afterward, the effect of process parameters and heat treatment conditions on mechanical properties are summarized and reviewed. Finally, the remaining issues and suggestions on future research on L-PBF of martensitic precipitation-hardened stainless steels are put forward. Full article

(This article belongs to the Special Issue AM-PBF Processes and Joining Similar/Dissimilar PBF Materials: Quo Vadis?)

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