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Material Analysis of Additively Manufactured Metals

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

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 12187

Special Issue Editor


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Guest Editor
Regional Technological Institute, University of West Bohemia, Univerzitni 8, 30614 Plzen, Czech Republic
Interests: the relationship between processing parameter microstructures and the mechanical properties of metals; microstructure analysis of metals with light and scanning electron microscopy; additively manufactured metals; advanced high-strength steels; in situ testing
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Special Issue Information

Dear Colleagues,

Additive manufacturing (AM) allows for the design of innovative and lightweight products with complex geometries and improved functional and mechanical properties. However, AM is still facing some material issues, for example, high residual stresses, pores, and impurities, and lower impact toughens and creep resistance, than corresponding conventional material. Intensive material research is still necessary to obtain reliable and high-quality products.

This Special Issue will cover the latest advances in the field of the additive manufacturing of metals. Contributions focused on the material aspects of metal additive manufacturing on any of the following topics will be of a particular interest: the effect of AM parameters and subsequent post-treatment parameters on microstructures and the mechanical properties of metals; creep and fatigue; failure mechanisms and crack formation; in-situ testing; the study of phase transformations during AM and/or subsequent heat treatment; the determination and reduction of residual stresses and porosity; the production and characterization of welds and joints of AM metals, including hybrid joins; the thermal and deformation stability of AM metals; the monitoring, description, and simulations of material behavior during the AM process.

It is my pleasure to invite you to contribute to this Special Issue. Original, high-quality research articles and reviews are encouraged for submission.

Dr. Ludmila Kučerová
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. Materials is an international peer-reviewed open access semimonthly 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

  • Effect of processing parameters on microstructures and mechanical properties
  • Improvement of mechanical properties of AM metals
  • Porosity of AM products
  • Characterization of material behavior during AM process
  • Welds and joints of AM metals
  • Failure mechanisms and crack formation.

Published Papers (4 papers)

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Research

14 pages, 6605 KiB  
Article
Optimization of the Post-Process Heat Treatment Strategy for a Near-α Titanium Base Alloy Produced by Laser Powder Bed Fusion
by Christian Fleißner-Rieger, Tanja Pfeifer, Christoph Turk and Helmut Clemens
Materials 2022, 15(3), 1032; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15031032 - 28 Jan 2022
Cited by 5 | Viewed by 2725
Abstract
During the last decades, titanium alloys have been of great interest for lightweight applications due to their high strength in combination with a low material density. Current research activities focus on the investigation of near-α titanium alloys produced by laser powder bed fusion [...] Read more.
During the last decades, titanium alloys have been of great interest for lightweight applications due to their high strength in combination with a low material density. Current research activities focus on the investigation of near-α titanium alloys produced by laser powder bed fusion (LPBF). These alloys are known for their superior tensile strength and high creep resistance. This study focuses on the optimization of post-process heat treatments and the impact on tensile and creep strength of a LPBF produced Ti6242S alloy. Therefore, a variety of annealing steps were conducted to gain knowledge about the decomposition process of the non-equilibrium as-built microstructure and the arising influence on the mechanical properties. Components made of Ti6242S and produced by LPBF reveal an extraordinarily high ultimate tensile strength of about 1530 MPa at room temperature, but show a low elongation at fracture (A5 = 4.3%). Based on microstructure-property relationships, this study recommends precise heat treatments on how to improve the desired mechanical properties in terms of strength, ductility as well as creep resistance. Moreover, this study shows a triplex heat treatment, which enhances the elongation at fracture (A5) to 16.5%, while the ultimate tensile strength is still at 1100 MPa. Full article
(This article belongs to the Special Issue Material Analysis of Additively Manufactured Metals)
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18 pages, 11163 KiB  
Article
Production of Hybrid Joints by Selective Laser Melting of Maraging Tool Steel 1.2709 on Conventionally Produced Parts of the Same Steel
by Ludmila Kučerová, Ivana Zetková, Štěpán Jeníček and Karolína Burdová
Materials 2021, 14(9), 2105; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14092105 - 21 Apr 2021
Cited by 7 | Viewed by 1557
Abstract
Joining additively manufactured (AM) complex shaped parts to larger conventionally produced parts can lead to innovative product designs. Another alternative is direct deposition on a conventional semi-product. Therefore, similar joints of maraging tool steel 1.2709 were produced by AM deposition of powder of [...] Read more.
Joining additively manufactured (AM) complex shaped parts to larger conventionally produced parts can lead to innovative product designs. Another alternative is direct deposition on a conventional semi-product. Therefore, similar joints of maraging tool steel 1.2709 were produced by AM deposition of powder of this steel on a bulk conventionally manufactured steel part. The resulting hybrid parts were solution annealed and precipitation hardened. Solution annealing at 820 °C for 20 min was followed by furnace cooling. Precipitation hardening was performed at 490 °C for 6 h. The mechanical properties of the samples were characterised using tensile testing and hardness measurement across the joint. Metallographic analysis was also carried out. The tensile properties of the AM and conventionally produced steel after equivalent heat treatments were also determined as the reference values. The mechanical properties of the hybrid parts are close to the properties of both steels. The hybrid parts in the as-built condition had a tensile strength of 1029 MPa and a total elongation of 14%. Solution annealing did not change these properties significantly, except for yield strength, which decreased by approximately 150 MPa. After precipitation annealing, the strength was higher, 2011 MPa, and total elongation dropped to 5%. Full article
(This article belongs to the Special Issue Material Analysis of Additively Manufactured Metals)
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19 pages, 15600 KiB  
Article
Influence of Selective Laser Melting Technological Parameters on the Mechanical Properties of Additively Manufactured Elements Using 316L Austenitic Steel
by Janusz Kluczyński, Lucjan Śnieżek, Krzysztof Grzelak, Jacek Janiszewski, Paweł Płatek, Janusz Torzewski, Ireneusz Szachogłuchowicz and Krzysztof Gocman
Materials 2020, 13(6), 1449; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13061449 - 22 Mar 2020
Cited by 21 | Viewed by 3407
Abstract
The main aim of this study was to investigate the influence of different energy density values used for the additively manufactured elements using selective laser melting (SLM).The group of process parameters considered was selected from the first-stage parameters identified in preliminary research. Samples [...] Read more.
The main aim of this study was to investigate the influence of different energy density values used for the additively manufactured elements using selective laser melting (SLM).The group of process parameters considered was selected from the first-stage parameters identified in preliminary research. Samples manufactured using three different sets of parameter values were subjected to static tensile and compression tests. The samples were also subjected to dynamic Split–Hopkinson tests. To verify the microstructural changes after the dynamic tests, microstructural analyses were conducted. Additionally, the element deformation during the tensile tests was analyzed using digital image correlation (DIC). To analyze the influence of the selected parameters and verify the layered structure of the manufactured elements, sclerometer scratch hardness tests were carried out on each sample. Based on the research results, it was possible to observe the porosity growth mechanism and its influence on the material strength (including static and dynamic tests). Parameters modifications that caused 20% lower energy density, as well as elongation of the elements during tensile testing, decreased twice, which was strictly connected with porosity growth. An increase of energy density, by almost three times, caused a significant reduction of force fluctuations differences between both tested surfaces (parallel and perpendicular to the building platform) during sclerometer hardness testing. That kind of phenomenon had been taken into account in the microstructure investigations before and after dynamic testing, where it had been spotted as a positive impact on material deformations based on fused material formation after SLM processing. Full article
(This article belongs to the Special Issue Material Analysis of Additively Manufactured Metals)
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15 pages, 4942 KiB  
Article
Laser Welding of SLM-Manufactured Tubes Made of IN625 and IN718
by Torsten Jokisch, Angelina Marko, Sergej Gook, Ömer Üstündag, Andrey Gumenyuk and Michael Rethmeier
Materials 2019, 12(18), 2967; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12182967 - 12 Sep 2019
Cited by 20 | Viewed by 3932
Abstract
The advantage of selective laser melting (SLM) is its high accuracy and geometrical flexibility. Because the maximum size of the components is limited by the process chamber, possibilities must be found to combine several parts manufactured by SLM. An application where this is [...] Read more.
The advantage of selective laser melting (SLM) is its high accuracy and geometrical flexibility. Because the maximum size of the components is limited by the process chamber, possibilities must be found to combine several parts manufactured by SLM. An application where this is necessary, is, for example, the components of gas turbines, such as burners or oil return pipes, and inserts, which can be joined by circumferential welds. However, only a few investigations to date have been carried out for the welding of components produced by SLM. The object of this paper is, therefore, to investigate the feasibility of laser beam welding for joining SLM tube connections made of nickel-based alloys. For this purpose, SLM-manufactured Inconel 625 and Inconel 718 tubes were welded with a Yb:YAG disk laser and subsequently examined for residual stresses and defects. The results showed that the welds had no significant influence on the residual stresses. A good weld quality could be achieved in the seam circumference. However, pores and pore nests were found in the final overlap area, which meant that no continuous good welding quality could be accomplished. Pore formation was presumably caused by capillary instabilities when the laser power was ramped out. Full article
(This article belongs to the Special Issue Material Analysis of Additively Manufactured Metals)
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