Special Issue "Microstructure and Mechanical Properties of Metallic Alloys Produced by Additive Manufacturing"

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

Deadline for manuscript submissions: closed (30 June 2018)

Special Issue Editor

Guest Editor
Prof. Dr. Maurizio Vedani

Dipartimento di Meccanica, Politecnico di Milano, Via Giuseppe La Masa 1, 20156 Milano, Italy
Website | E-Mail
Interests: metallurgy of light alloys; additive manufacturing of metals; plastic deformation of steels and non-ferrous alloys; thermomechanical and surface treatments of metals

Special Issue Information

Dear Colleagues,

Additive manufacturing (AM) of metals is revolutionizing the way of conceiving parts and structures. It enables a high degree of design freedom, allowing the production of objects with optimized shapes for specific applications. Several processes have been developed in the last few decades, belonging the group of Additive Layer Manufacturing (e.g., selective laser melting, electron beam melting) and to that of Direct Metal Deposition.

From the material perspective, the peculiar solidification conditions induced by AM processes allow to generate specific microstructures and properties that still need to be investigated deeply. In addition, large opportunities are available for the design of new dedicated alloys showing an improved ability to be processed, as well as higher performances.

The aim of this Special Issue is to highlight recent innovations related to additive manufacturing of metals with a special emphasis on new properties and innovative materials tailored for this processing technique.

Prof. Dr. Maurizio  Vedani
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 1200 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

  • additive manufacturing
  • selective laser melting
  • electron beam melting
  • direct metal deposition
  • microstructure
  • texture
  • mechanical behavior
  • solidification condition

Published Papers (3 papers)

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Research

Open AccessArticle Research on Selective Laser Melting of Ti6Al4V: Surface Morphologies, Optimized Processing Zone, and Ductility Improvement Mechanism
Metals 2018, 8(7), 471; https://doi.org/10.3390/met8070471
Received: 24 May 2018 / Revised: 13 June 2018 / Accepted: 15 June 2018 / Published: 21 June 2018
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Abstract
The quality and mechanical properties of titanium alloy fabricated using selective laser melting (SLM) are critical to the adoption of the process which has long been impeded by the lack of uniformity in SLM-fabrication parameter optimization. In order to address this problem, laser
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The quality and mechanical properties of titanium alloy fabricated using selective laser melting (SLM) are critical to the adoption of the process which has long been impeded by the lack of uniformity in SLM-fabrication parameter optimization. In order to address this problem, laser power and scanning speed were combined into linear energy density as an independent variable, while surface morphology was defined as a metric. Based on full-factor experiments, the surface quality of SLM-fabricated titanium alloy was classified into five zones: severe over-melting zone, high-energy density nodulizing zone, smooth forming zone, low-energy density nodulizing zone, and sintering zone. The mechanism resulting in the creation of each zone was analyzed. Parameter uniformity was achieved by establishing a parameter window for each zone, and it also revealed that under smooth forming conditions, the relationship of linear energy density to the quality of the formed surface is not linear. It was also found that fabrication efficiency could be improved in the condition of the formation of a smooth surface by increasing laser power and scanning speed. In addition, maximum elongation of the SLM-fabricated titanium alloy increased when the densified parts were processed using an appropriate heat treatment, from a low value of 5.79% to 10.28%. The mechanisms of change in ductility of the alloy were thoroughly analyzed from the perspectives of surface microstructure and fracture morphology. Results indicate that after heat treatment, the microcosmic structure of the alloy was converted from acicular martensite α’ phase to a layered α+β double-phase structure, the fracture type also changed from quasi-cleavage to ductile fracture. Full article
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Open AccessArticle Laser Powder Bed Fusion of a High Strength Al-Si-Zn-Mg-Cu Alloy
Metals 2018, 8(5), 300; https://doi.org/10.3390/met8050300
Received: 14 March 2018 / Revised: 18 April 2018 / Accepted: 24 April 2018 / Published: 26 April 2018
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Abstract
Al-Si-Zn-Mg-Cu samples were produced using Laser Powder Bed Fusion from mixed AlSi10Mg and 7075 powders. It was observed that the introduction of silicon to an Al-Zn-Mg-Cu alloy strongly reduced the crack density, probably because of the reduction of the solidification range, the improved
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Al-Si-Zn-Mg-Cu samples were produced using Laser Powder Bed Fusion from mixed AlSi10Mg and 7075 powders. It was observed that the introduction of silicon to an Al-Zn-Mg-Cu alloy strongly reduced the crack density, probably because of the reduction of the solidification range, the improved fluidity of the molten phase and the reduction of the coefficient of thermal expansion. The density measurements showed that crack-free samples can be successfully produced with this powder mixture. The obtained Al-Si-Zn-Mg-Cu samples were characterized in terms of microstructure, hardness and tensile properties showing that this composition is very promising for future powder bed additive manufacturing processes. Full article
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Open AccessArticle Sliding Contact Wear Damage of EBM built Ti6Al4V: Influence of Process Induced Anisotropic Microstructure
Metals 2018, 8(2), 131; https://doi.org/10.3390/met8020131
Received: 17 November 2017 / Revised: 4 February 2018 / Accepted: 9 February 2018 / Published: 13 February 2018
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Abstract
Process-induced directional microstructure is identified as one of the key factors of anisotropic mechanical properties. This directional property significantly affects surface contact fatigue and corrosion of electron beam melting (EBM) built biomedical implants. In the current study, material removal on EBM built titanium
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Process-induced directional microstructure is identified as one of the key factors of anisotropic mechanical properties. This directional property significantly affects surface contact fatigue and corrosion of electron beam melting (EBM) built biomedical implants. In the current study, material removal on EBM built titanium (Ti6Al4V) subjected to reciprocating motion of commercially pure titanium spherical slider is investigated to identify the influence of the process-induced layered structure and environments on wear damage. Specimens developed by two different build orientations are mechanically stimulated using different sliding directions with nominally elastic normal load in dry, passivating, and synovial environments. It was noticed that EBM orientation significantly changes wear behavior in ambient environment. Wear resistance of mill-annealed Ti6Al4V was improved in passivating environment. Implications to improve useful life of orthopedic implants are discussed. Full article
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Figure 1

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