Special Issue "Additive Manufacturing of Ferrous Materials"

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

Deadline for manuscript submissions: 31 July 2018

Special Issue Editors

Guest Editor
Prof. Dr. Pavel Krakhmalev

Department of Engineering and Physics, Karlstad University, SE-651 88, Karlstad, Sweden
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Interests: microstructure property relationships in advanced metallic materials; wear and failure analysis; additive manufacturing; new titanium alloys for medical applications; additive manufacturing of ferrous materials
Guest Editor
Prof. Igor Yadroitsev

Department of Mechanical and Mechatronic Engineering, Bloemfontein, Central University of Technology, Free State, South Africa, 9300
Website | E-Mail
Interests: optimization of additive manufacturing process; development of process parameters; development of new alloys; biomedical materials; titanium alloys

Special Issue Information

Dear Colleagues,

Laser additive manufacturing (AM) is acknowledged as being a resource-efficient sustainable technology, providing the manufacturing of objects of complex shapes, containing internal channels and cavities, with less wastage of materials and shorter lead times. Two large branches of laser additive manufacturing technology are powder bed fusion, often referred to as selective laser melting (SLM), and directed energy deposition, also called laser metal deposition (LMD).

Ferrous materials are well-known structural, tool, automotive, and civil materials. In general, steels and cast irons are cheaper than nonferrous alloys, are widely used and cover very broad range of properties and applications. Because of this, ferrous materials attract high interest as cost-effective materials for AM.

During AM manufacturing, powder material is remolten, rapidly cooled, subjected to thermal shock and repeatable thermal cycling due to layer-by-layer maturing of the manufacturing process. As such, selection of materials for laser additive manufacturing is a challenge. Presently, a limited number of ferrous materials, steels, has been proven to be perfectly suitable for additive manufacturing. Substantial research and development efforts are, therefore, directed to the development of process parameters suitable for pore-free manufacturing of existing materials or to design new material grades tolerant to AM.

This Special Issue is dedicated to all aspects of additive manufacturing of ferrous materials to show recent advances in this field. We are looking forward to receiving submissions dedicated to both, powder bed fusion and directed energy deposition of ferrous materials for structural, tooling, medical and other applications. Original contributions related to development of process parameters, manufacturing strategies, development of new steel grades for AM, formation of microstructure, characterization of defects, microstructure-properties relationship in AM manufactured ferrous alloys are welcome in a form of short communications, full-length articles, and reviews.

Prof. Dr. Pavel Krakhmalev
Prof. Dr. Igor Yadroitsev
Guest Editors

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
  • powder bed fusion
  • directed energy deposition
  • new ferrous alloy for AM
  • processing strategies and optimization of process parameters
  • defects and porosity
  • microstructure formation and evolution
  • mechanical properties

Published Papers (3 papers)

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Research

Open AccessArticle Characterization of 17-4PH Single Tracks Produced at Different Parametric Conditions towards Increased Productivity of LPBF Systems—The Effect of Laser Power and Spot Size Upscaling
Metals 2018, 8(7), 475; https://doi.org/10.3390/met8070475
Received: 7 May 2018 / Revised: 2 June 2018 / Accepted: 2 June 2018 / Published: 22 June 2018
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Abstract
Global industrial adoption of laser-based powder bed fusion (LPBF) technology is still limited by the production speed, the size of the build envelope, and therefore the maximum part size that can be produced. The cost of LPBF can be driven down further by
[...] Read more.
Global industrial adoption of laser-based powder bed fusion (LPBF) technology is still limited by the production speed, the size of the build envelope, and therefore the maximum part size that can be produced. The cost of LPBF can be driven down further by improving the build rates without compromising structural integrity. A common approach is that the build rate can be improved by increasing the laser power and beam diameter to instantly melt a large area of powder, thus reducing the scanning time for each layer. The aim of this study was to investigate the aspects of upscaling LPBF processing parameters on the characteristic formation of stable single tracks, which are the primary building blocks for this technology. Two LPBF systems operating independently, using different parameter regimes, were used to produce the single tracks on a solid substrate deposited with a thin powder layer. The results obtained indicate that higher laser power and spot size can be used to produce stable tracks while the linear energy input is increased. It was also shown statistically that the geometrical characteristics of single tracks are mainly affected by the laser power and scanning speed during the scanning of a thin powder layer. Full article
(This article belongs to the Special Issue Additive Manufacturing of Ferrous Materials)
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Graphical abstract

Open AccessArticle Crystallographic Features of Microstructure in Maraging Steel Fabricated by Selective Laser Melting
Metals 2018, 8(6), 440; https://doi.org/10.3390/met8060440
Received: 25 May 2018 / Revised: 7 June 2018 / Accepted: 8 June 2018 / Published: 9 June 2018
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Abstract
This study characterizes the microstructure and its associated crystallographic features of bulk maraging steels fabricated by selective laser melting (SLM) combined with a powder bed technique. The fabricated sample exhibited characteristic melt pools in which the regions had locally melted and rapidly solidified.
[...] Read more.
This study characterizes the microstructure and its associated crystallographic features of bulk maraging steels fabricated by selective laser melting (SLM) combined with a powder bed technique. The fabricated sample exhibited characteristic melt pools in which the regions had locally melted and rapidly solidified. A major part of these melt pools corresponded with the ferrite (α) matrix, which exhibited a lath martensite structure with a high density of dislocations. A number of fine retained austenite (γ) with a <001> orientation along the build direction was often localized around the melt pool boundaries. The orientation relationship of these fine γ grains with respect to the adjacent α grains in the martensite structure was (111)γ//(011)α and [-101]γ//[-1-11]α (Kurdjumov–Sachs orientation relationship). Using the obtained results, we inferred the microstructure development of maraging steels during the SLM process. The results depict that new and diverse high-strength materials can be used to develop industrial molds and dies. Full article
(This article belongs to the Special Issue Additive Manufacturing of Ferrous Materials)
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Open AccessArticle An Investigation of the Microstructure and Fatigue Behavior of Additively Manufactured AISI 316L Stainless Steel with Regard to the Influence of Heat Treatment
Metals 2018, 8(4), 220; https://doi.org/10.3390/met8040220
Received: 23 February 2018 / Revised: 22 March 2018 / Accepted: 23 March 2018 / Published: 28 March 2018
Cited by 1 | PDF Full-text (13327 KB) | HTML Full-text | XML Full-text
Abstract
To exploit the whole potential of Additive Manufacturing, it is essential to investigate the complex relationships between Additive Manufacturing processes, the resulting microstructure, and mechanical properties of the materials and components. In the present work, Selective Laser Melted (SLM) (process category: powder bed
[...] Read more.
To exploit the whole potential of Additive Manufacturing, it is essential to investigate the complex relationships between Additive Manufacturing processes, the resulting microstructure, and mechanical properties of the materials and components. In the present work, Selective Laser Melted (SLM) (process category: powder bed fusion), Laser Deposition Welded (LDW) (process category: direct energy deposition) and, for comparison, Continuous Casted and then hot and cold drawn (CC) austenitic stainless steel AISI 316L blanks were investigated with regard to their microstructure and mechanical properties. To exclude the influence of surface topography and focus the investigation on the volume microstructure, the blanks were turned into final geometry of specimens. The additively manufactured (AM-) blanks were manufactured in both the horizontal and vertical building directions. In the horizontally built specimens, the layer planes are perpendicular and in vertical building direction, they are parallel to the load axis of the specimens. The materials from different manufacturing processes exhibit different chemical composition and hence, austenite stability. Additionally, all types of blanks were heat treated (2 h, 1070 °C, H2O) and the influence of the heat treatment on the properties of differently manufactured materials were investigated. From the cyclic deformation curves obtained in the load increase tests, the anisotropic fatigue behavior of the AM-specimens could be detected with only one specimen in each building direction for the different Additive Manufacturing processes, which could be confirmed by constant amplitude tests. The results showed higher fatigue strength for horizontally built specimens compared to the vertical building direction. Furthermore, the constant amplitude tests show that the austenite stability influences the fatigue behavior of differently manufactured 316L. Using load increase tests as an efficient rating method of the anisotropic fatigue behavior, the influence of the heat treatment on anisotropy could be determined with a small number of specimens. These investigations showed no significant influence of the heat treatment on the anisotropic behavior of the AM-specimens. Full article
(This article belongs to the Special Issue Additive Manufacturing of Ferrous Materials)
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