Special Issue "3D Printing of Metals"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (31 December 2016)

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editor

Guest Editor
Assoc. Prof. Manoj Gupta

Materials Group, Department of Mechanical Engineering, NUS, 9 Engineering Drive 1, 117576 Singapore
Website | E-Mail
Interests: processing; characterization; lightweight materials; nanocomposites

Special Issue Information

Dear Colleagues,

3D printing is an emerging technique of immense engineering importance, capable of transforming the way we make components. However, it faces numerous challenges in order to become an integral part of manufacturing industry. This Special Issue, thus, focuses on inviting contributions on all aspects of the 3D printing of metals. The main themes are listed as follows:

  1. Issues related to 3D processing techniques for metals.
  2. Microstructural evolution during 3D printing
  3. Characteristics of 3D printed materials.
  4. Applications of 3D printed metal-based materials.

Contributions from academic researchers, practicing engineers, and industry are equally desirable to enable the readers to appreciate different points of view.

Dr. Manoj Gupta
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 papers will be 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 1000 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

  • Processing
  • Sintering
  • Microstructural evolution, physical, mechanical, thermal, chemical properties
  • Numerical simulation
  • Composites
  • Applications (automotive, aviation, consumer electronics, sports, bio-medical, etc.)

Published Papers (10 papers)

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Editorial

Jump to: Research, Review

Open AccessEditorial 3D Printing of Metals
Metals 2017, 7(10), 403; doi:10.3390/met7100403
Received: 26 September 2017 / Revised: 27 September 2017 / Accepted: 28 September 2017 / Published: 29 September 2017
Cited by 1 | PDF Full-text (125 KB) | HTML Full-text | XML Full-text
Abstract
The potential benefits that could be derived if the science and technology of 3D printing were to be established have been the crux behind monumental efforts by governments, in most countries, that invest billions of dollars to develop this manufacturing technology.[...] Full article
(This article belongs to the Special Issue 3D Printing of Metals) Printed Edition available

Research

Jump to: Editorial, Review

Open AccessArticle Case Studies on Local Reinforcement of Sheet Metal Components by Laser Additive Manufacturing
Metals 2017, 7(4), 113; doi:10.3390/met7040113
Received: 31 December 2016 / Revised: 15 March 2017 / Accepted: 20 March 2017 / Published: 25 March 2017
Cited by 1 | PDF Full-text (7952 KB) | HTML Full-text | XML Full-text
Abstract
This paper details two case studies that make use of laser metal deposition for local reinforcement of sheet metal components. Two benchmark scenarios are investigated, both using aluminum alloys: (i) using laser cladding to increase the stiffness of a pre-formed component, and (ii)
[...] Read more.
This paper details two case studies that make use of laser metal deposition for local reinforcement of sheet metal components. Two benchmark scenarios are investigated, both using aluminum alloys: (i) using laser cladding to increase the stiffness of a pre-formed component, and (ii) applying a local cladding on sheet metal for increasing the thickness prior to a hole-flanging operation. The results show that both routes are viable. Applying claddings onto sheet metal before a metal forming operation must ensure suitable formability, which may be limited by the layer material and undesired changes in the microstructure of the sheet. The limited formability has to be taken into account in the design of the forming operation. Cladding onto already formed components has to cope with inevitable distortion of the component. Nevertheless, introducing additive manufacturing into the field of sheet metal forming opens the possibility to produce new products such as tailored laser-cladded blanks, combinations of sheet and bulk components and to develop new methods such as stiffness management in lightweight design. Full article
(This article belongs to the Special Issue 3D Printing of Metals) Printed Edition available
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Open AccessArticle Comparison of Single Ti6Al4V Struts Made Using Selective Laser Melting and Electron Beam Melting Subject to Part Orientation
Metals 2017, 7(3), 91; doi:10.3390/met7030091
Received: 1 December 2016 / Revised: 8 March 2017 / Accepted: 9 March 2017 / Published: 11 March 2017
Cited by 1 | PDF Full-text (1799 KB) | HTML Full-text | XML Full-text
Abstract
The use of additive manufacturing technologies to produce lightweight or functional structures is widespread. Especially Ti6Al4V plays an important role in this development field and parts are manufactured and analyzed with the aim to characterize the mechanical properties of
[...] Read more.
The use of additive manufacturing technologies to produce lightweight or functional structures is widespread. Especially Ti6Al4V plays an important role in this development field and parts are manufactured and analyzed with the aim to characterize the mechanical properties of open-porous structures and to generate scaffolds with properties specific to their intended application. An SLM and an EBM process were used respectively to fabricate the Ti6Al4V single struts. For mechanical characterization, uniaxial compression tests and hardness measurements were conducted. Furthermore, the struts were manufactured in different orientations for the determination of the mechanical properties. Roughness measurements and a microscopic characterization of the struts were also carried out. Some parts were characterized following heat treatment (hot isostatic pressing). A functional correlation was found between the compressive strength and the slenderness ratio (λ) as well as the equivalent diameter (d) and the height (L) of EBM and SLM parts. Hardness investigations revealed considerable differences related to the microstructure. An influence of heat treatment as well as of orientation could be determined. In this work, we demonstrate the influence of the fabrication quality of single struts, the roughness and the microstructure on mechanical properties as a function of orientation. Full article
(This article belongs to the Special Issue 3D Printing of Metals) Printed Edition available
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Open AccessArticle Investigation on Porosity and Microhardness of 316L Stainless Steel Fabricated by Selective Laser Melting
Metals 2017, 7(2), 64; doi:10.3390/met7020064
Received: 5 January 2017 / Accepted: 15 February 2017 / Published: 20 February 2017
Cited by 3 | PDF Full-text (4243 KB) | HTML Full-text | XML Full-text
Abstract
This study investigates the porosity and microhardness of 316L stainless steel samples fabricated by selective laser melting (SLM). The porosity content was measured using the Archimedes method and the advanced X-ray computed tomography (XCT) scan. High densification level (≥99%) with a low average
[...] Read more.
This study investigates the porosity and microhardness of 316L stainless steel samples fabricated by selective laser melting (SLM). The porosity content was measured using the Archimedes method and the advanced X-ray computed tomography (XCT) scan. High densification level (≥99%) with a low average porosity content (~0.82%) were obtained from the Archimedes method. The highest porosity content in the XCT-scanned sample was ~0.61. However, the pores in the SLM samples for both cases (optical microscopy and XCT) were not uniformly distributed. The higher average microhardness values in the SLM samples compared to the wrought manufactured counterpart are attributed to the fine microstructures from the localised melting and rapid solidification rate of the SLM process. Full article
(This article belongs to the Special Issue 3D Printing of Metals) Printed Edition available
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Open AccessArticle Morphology Analysis of a Multilayer Single Pass via Novel Metal Thin-Wall Coating Forming
Metals 2016, 6(12), 313; doi:10.3390/met6120313
Received: 30 June 2016 / Revised: 22 November 2016 / Accepted: 24 November 2016 / Published: 9 December 2016
PDF Full-text (2947 KB) | HTML Full-text | XML Full-text
Abstract
Through using a novel micro-coating metal additive manufacturing (MCMAM) process in this study, the forming characteristics of the multilayer single-pass specimens were investigated. The forming defects including the porosity and the bonding quality between layers were analyzed. Moreover, we also attempted to study
[...] Read more.
Through using a novel micro-coating metal additive manufacturing (MCMAM) process in this study, the forming characteristics of the multilayer single-pass specimens were investigated. The forming defects including the porosity and the bonding quality between layers were analyzed. Moreover, we also attempted to study the effect of process parameters such as flow rate, deposition velocity, and layer thickness on the forming morphology. Based on the results, the optimization of process parameters was conducted for the fabrication of thin-wall MCMAM. Finally, estimation criteria for the integrity of the interfacial bond were established. Full article
(This article belongs to the Special Issue 3D Printing of Metals) Printed Edition available
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Open AccessArticle Effect of the Thermodynamic Behavior of Selective Laser Melting on the Formation of In situ Oxide Dispersion-Strengthened Aluminum-Based Composites
Metals 2016, 6(11), 286; doi:10.3390/met6110286
Received: 18 July 2016 / Revised: 8 November 2016 / Accepted: 9 November 2016 / Published: 19 November 2016
Cited by 1 | PDF Full-text (2043 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a comprehensive investigation of the phase and microstructure, the thermodynamic behavior within the molten pool, and the growth mechanism of in situ oxide dispersion-strengthened (ODS) aluminum-based composites processed by a selective laser melting (SLM) additive manufacturing/3D printing process. The phase
[...] Read more.
This paper presents a comprehensive investigation of the phase and microstructure, the thermodynamic behavior within the molten pool, and the growth mechanism of in situ oxide dispersion-strengthened (ODS) aluminum-based composites processed by a selective laser melting (SLM) additive manufacturing/3D printing process. The phase and microstructure were characterized by X-ray diffraction (XRD) and a scanning electronic microscope (SEM) equipped with EDX, respectively. The thermodynamic behavior within the molten pool was investigated for a comprehensive understanding on the growth mechanism of the SLM-processed composite using a finite volume method (FVM). The results revealed that the in situ Al2Si4O10 ODS Al-based composites were successfully fabricated by SLM. Combined with the XRD spectrum and EDX analysis, the new silica-rich Al2Si4O10 reinforcing phase was identified, which was dispersed around the grain boundaries of the aluminum matrix under a reasonable laser power of 200 W. Combined with the activity of Marangoni convection and repulsion forces, the characteristic microstructure of SLM-processed Al2Si4O10 ODS Al-based composites tended to transfer from the irregular network structure to the nearly sphere-like network structure in regular form by increasing the laser power. The formation mechanism of the microstructure of SLM-processed Al2Si4O10 ODS Al-based composites is thoroughly discussed herein. Full article
(This article belongs to the Special Issue 3D Printing of Metals) Printed Edition available
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Open AccessFeature PaperArticle Microstructure and Wear Properties of Electron Beam Melted Ti-6Al-4V Parts: A Comparison Study against As-Cast Form
Metals 2016, 6(11), 284; doi:10.3390/met6110284
Received: 29 October 2016 / Revised: 12 November 2016 / Accepted: 15 November 2016 / Published: 18 November 2016
Cited by 3 | PDF Full-text (6448 KB) | HTML Full-text | XML Full-text
Abstract
Ti-6Al-4V (Ti64) parts of varying thicknesses were additively manufactured (AM) by the powder-bed-based electron beam melting (EBM) technique. Microstructure and wear properties of these EBM-built Ti-6Al-4V parts have been investigated in comparison with conventionally cast Ti64 samples. Sliding wear tests were conducted using
[...] Read more.
Ti-6Al-4V (Ti64) parts of varying thicknesses were additively manufactured (AM) by the powder-bed-based electron beam melting (EBM) technique. Microstructure and wear properties of these EBM-built Ti-6Al-4V parts have been investigated in comparison with conventionally cast Ti64 samples. Sliding wear tests were conducted using a ball-on-disc micro-tribometer under ambient conditions. Experimental results reveal that EBM-built Ti64 samples exhibited higher microhardness and an overall larger coefficient of friction as compared to the as-cast counterpart. Of interest is that the corresponding specific wear volumes were lower for EBM-built Ti64 samples, while the as-cast Ti64 showed the poorest wear resistance despite its lower coefficient of friction. Wear mechanisms were provided in terms of quantitative microstructural characterization and detailed analysis on coefficient of friction (COF) curves. Full article
(This article belongs to the Special Issue 3D Printing of Metals) Printed Edition available
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Open AccessArticle A Lightweight Structure Redesign Method Based on Selective Laser Melting
Metals 2016, 6(11), 280; doi:10.3390/met6110280
Received: 10 September 2016 / Revised: 19 October 2016 / Accepted: 1 November 2016 / Published: 16 November 2016
PDF Full-text (17974 KB) | HTML Full-text | XML Full-text
Abstract
The purpose of this paper is to present a new design method of lightweight parts fabricated by selective laser melting (SLM) based on the “Skin-Frame” and to explore the influence of fabrication defects on SLM parts with different sizes. Some standard lattice parts
[...] Read more.
The purpose of this paper is to present a new design method of lightweight parts fabricated by selective laser melting (SLM) based on the “Skin-Frame” and to explore the influence of fabrication defects on SLM parts with different sizes. Some standard lattice parts were designed according to the Chinese GB/T 1452-2005 standard and manufactured by SLM. Then these samples were tested in an MTS Insight 30 compression testing machine to study the trends of the yield process with different structure sizes. A set of standard cylinder samples were also designed according to the Chinese GB/T 228-2010 standard. These samples, which were made of iron-nickel alloy (IN718), were also processed by SLM, and then tested in the universal material testing machine INSTRON 1346 to obtain their tensile strength. Furthermore, a lightweight redesigned method was researched. Then some common parts such as a stopper and connecting plate were redesigned using this method. These redesigned parts were fabricated and some application tests have already been performed. The compression testing results show that when the minimum structure size is larger than 1.5 mm, the mechanical characteristics will hardly be affected by process defects. The cylinder parts were fractured by the universal material testing machine at about 1069.6 MPa. These redesigned parts worked well in application tests, with both the weight and fabrication time of these parts reduced more than 20%. Full article
(This article belongs to the Special Issue 3D Printing of Metals) Printed Edition available
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Open AccessArticle Aging Behaviour and Mechanical Performance of 18-Ni 300 Steel Processed by Selective Laser Melting
Metals 2016, 6(9), 218; doi:10.3390/met6090218
Received: 2 August 2016 / Revised: 31 August 2016 / Accepted: 5 September 2016 / Published: 8 September 2016
Cited by 9 | PDF Full-text (9820 KB) | HTML Full-text | XML Full-text
Abstract
An 18-Ni 300 grade maraging steel was processed by selective laser melting and an investigation was carried out on microstructural and mechanical behaviour as a function of aging condition. Owing to the rapid cooling rate, the as-built alloy featured a full potential for
[...] Read more.
An 18-Ni 300 grade maraging steel was processed by selective laser melting and an investigation was carried out on microstructural and mechanical behaviour as a function of aging condition. Owing to the rapid cooling rate, the as-built alloy featured a full potential for precipitate strengthening, without the need of a solution treatment prior to aging. The amount of reversed austenite found in the microstructure increased after aging and revealed to depend on aging temperature and time. Similarly to the corresponding wrought counterpart, also in the selective laser-melted 18-Ni 300 alloy, aging promoted a dramatic increase in strength with respect to the as-built condition and a drop in tensile ductility. No systematic changes were found in tensile properties as a function of measured amount of austenite. It is proposed that the submicrometric structure and the phase distribution inherited by the rapid solidification condition brought by selective laser melting are such that changes in tensile strength and ductility are mainly governed by the effects brought by the strengthening precipitates, whereas the concurrent reversion of the γ-Fe phase in different amounts seems to play a minor role. Full article
(This article belongs to the Special Issue 3D Printing of Metals) Printed Edition available
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Review

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Open AccessFeature PaperReview Selective Laser Melting of Magnesium and Magnesium Alloy Powders: A Review
Metals 2017, 7(1), 2; doi:10.3390/met7010002
Received: 9 September 2016 / Revised: 9 November 2016 / Accepted: 15 December 2016 / Published: 26 December 2016
Cited by 6 | PDF Full-text (6938 KB) | HTML Full-text | XML Full-text
Abstract
Magnesium-based materials are used primarily in developing lightweight structures owing to their lower density. Further, being biocompatible they offer potential for use as bioresorbable materials for degradable bone replacement implants. The design and manufacture of complex shaped components made of magnesium with good
[...] Read more.
Magnesium-based materials are used primarily in developing lightweight structures owing to their lower density. Further, being biocompatible they offer potential for use as bioresorbable materials for degradable bone replacement implants. The design and manufacture of complex shaped components made of magnesium with good quality are in high demand in the automotive, aerospace, and biomedical areas. Selective laser melting (SLM) is becoming a powerful additive manufacturing technology, enabling the manufacture of customized, complex metallic designs. This article reviews the recent progress in the SLM of magnesium based materials. Effects of SLM process parameters and powder properties on the processing and densification of the magnesium alloys are discussed in detail. The microstructure and metallurgical defects encountered in the SLM processed parts are described. Applications of SLM for potential biomedical applications in magnesium alloys are also addressed. Finally, the paper summarizes the findings from this review together with some proposed future challenges for advancing the knowledge in the SLM processing of magnesium alloy powders. Full article
(This article belongs to the Special Issue 3D Printing of Metals) Printed Edition available
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