Special Issue "Additive Manufacturing of Metals with Lasers"

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

Deadline for manuscript submissions: 30 June 2020.

Special Issue Editor

Prof. Patrice Peyre
E-Mail Website
Guest Editor
French National Centre for Scientific Research, Paris, France
Interests: additive manufacturing with lasers; laser surface treatments; laser welding of dissimilar metals
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

As you know, an exponentially growing interest in both the industrial and academic communities regarding additive manufacturing (AM) has arisen in the last 5 years following more than a decade of technical proofs of concept and improvements in laser-based AM techniques. Since then, many scientific fields have been addressed in detail in the literature, including (1) the physics of laser–powder (or wire)–melt pool interaction, (2) the optimization of process parameters to ensure optimum densification of parts, (3) the microstructures of as-built or thermally treated AM materials and, of course, (4) the mechanical or corrosion properties of manufactured parts. Experimental, analytical, or numerical means have been used to fulfill the requirements of AM developments. However, on all of these topics, a tremendous amount of work is still required to improve our global understanding of existing processes (direct energy deposition, powder bed laser fusion, metal binder jetting, etc.), develop novel processes, address modified or complex alloys (e.g., hot cracking sensitivity) or provide a more precise analysis of AM microstructures and their resulting properties. These are the global objectives of this Special Issue on Additive Manufacturing of Metals with Lasers, which is devoted to the most recent achievements on this highly attractive topic.

Prof. Patrice Peyre
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 1600 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

  • powder bed laser fusion (PBLF/SLM)
  • direct energy deposition (DED)
  • metal binder jetting (MBJ)
  • microstructures
  • corrosion
  • fatigue
  • residual stresses
  • numerical simulation

Published Papers (8 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Jump to: Review

Open AccessArticle
Thermal Fatigue Properties of H13 Hot-Work Tool Steels Processed by Selective Laser Melting
Metals 2020, 10(1), 116; https://doi.org/10.3390/met10010116 - 12 Jan 2020
Abstract
Currently, selective laser melting (SLM) is gaining widespread popularity as an alternative manufacturing technique for complex and customized parts, especially for hot-work and injection molding applications. In the present study, as the major factors for the failure of H13 hot-work die steels during [...] Read more.
Currently, selective laser melting (SLM) is gaining widespread popularity as an alternative manufacturing technique for complex and customized parts, especially for hot-work and injection molding applications. In the present study, as the major factors for the failure of H13 hot-work die steels during hot-working, thermal fatigue (TF) properties of H13 processed by SLM and a conventional technique were investigated. TF tests (650 °C/30 °C) were conducted on the as-selective laser melted (As-SLMed), thermally treated selective laser melted (T-SLMed), and forged (Forged) H13. Results show that the As-SLMed H13 exhibited the best TF resistance properties among the specimens herein (the shortest total crack length and highest hardness of 687 ± 12 HV5), whereas the Forged H13 exhibited the poorest TF resistance properties (the longest total crack length and lowest hardness of 590 ± 11 HV5) after TF tests. TF resistance properties were closely related to the initial and final hardness. Further microstructural investigations revealed that the typical cell-like substructures, increased amount of retained austenite, and most importantly, refined grain size were the main reasons for the improved TF resistance properties in the As-SLMed H13 compared to the Forged counterparts. Full article
(This article belongs to the Special Issue Additive Manufacturing of Metals with Lasers)
Show Figures

Figure 1

Open AccessArticle
Acoustic Properties of 316L Stainless Steel Lattice Structures Fabricated via Selective Laser Melting
Metals 2020, 10(1), 111; https://doi.org/10.3390/met10010111 - 11 Jan 2020
Abstract
A bulk specimen and two different lattice sandwich structures composed of 316L stainless steel were fabricated via selective laser melting. This study analysed the acoustic properties, including sound insulation and sound absorption, of the three kinds of structures, which were produced via selective [...] Read more.
A bulk specimen and two different lattice sandwich structures composed of 316L stainless steel were fabricated via selective laser melting. This study analysed the acoustic properties, including sound insulation and sound absorption, of the three kinds of structures, which were produced via selective laser melting under the same process parameters. The results showed that the difference in the unit structures, rather than microstructural difference, was the main reason for the difference in acoustic properties between the samples. Under the same process parameters, the microstructure of the different structures had the same cell structure. However, the sound absorption properties of the lattice sandwich structures were better than those of the bulk sample in the measured frequency range of 1–6.3 kHz. The lattice sandwich structure with 2.5 × 2.5 × 2.5 mm3 unit structures exhibited excellent sound insulation properties in the frequency range of 1–5 kHz. Full article
(This article belongs to the Special Issue Additive Manufacturing of Metals with Lasers)
Show Figures

Figure 1

Open AccessArticle
Influence of the Chemical Composition of the Used Powder on the Fatigue Behavior of Additively Manufactured Materials
Metals 2019, 9(12), 1285; https://doi.org/10.3390/met9121285 - 29 Nov 2019
Abstract
To exploit the whole potential of Additive Manufacturing (AM), a sound knowledge about the mechanical and especially cyclic properties of AM materials as well as their dependency on the process parameters is indispensable. In the presented work, the influence of chemical composition of [...] Read more.
To exploit the whole potential of Additive Manufacturing (AM), a sound knowledge about the mechanical and especially cyclic properties of AM materials as well as their dependency on the process parameters is indispensable. In the presented work, the influence of chemical composition of the used powder on the fatigue behavior of Selectively Laser Melted (SLM) and Laser Deposition Welded (LDW) specimens made of austenitic stainless steel AISI 316L was investigated. Therefore, in each manufacturing process two variations of chemical composition of the used powder were utilized. For qualitative characterization of the materials cyclic deformation behavior, load increase tests (LITs) were performed and further used for the physically based lifetime calculation method (PhyBaLLIT), enabling an efficient determination of stress (S)–number of cycles to failure (Nf) curves (S–Nf), which show excellent correlation to additionally performed constant amplitude tests (CATs). Moreover, instrumented cyclic indentation tests (PhyBaLCHT) were utilized to characterize the materials’ defect tolerance in a comparably short time. All material variants exhibit a high influence of microstructural defects on the fatigue properties. Consequently, for the SLM process a higher fatigue lifetime at lower stress amplitudes could be observed for the batch with a higher defect tolerance, resulting from a more pronounced deformation induced austenite–α’-martensite transformation. In correspondence to that, the batch of LDW material with an increased defect tolerance exhibit a higher fatigue strength. However, the differences in defect tolerance between the LDW batches is only slightly influenced by phase transformation and seems to be mainly governed by differences in hardening potential of the austenitic microstructure. Furthermore, a significantly higher fatigue strength could be observed for SLM material in relation to LDW specimens, because of a refined microstructure and smaller microstructural defects of SLM specimens. Full article
(This article belongs to the Special Issue Additive Manufacturing of Metals with Lasers)
Show Figures

Graphical abstract

Open AccessArticle
Investigation on Ti-6Al-4V Microstructure Evolution in Selective Laser Melting
Metals 2019, 9(12), 1270; https://doi.org/10.3390/met9121270 - 27 Nov 2019
Abstract
Selective laser melting (SLM) is an advanced additive manufacturing technique that can produce complex and accurate metal samples. Since the process performs local high heat input during a very short interaction time, the physical parameters in the solidification are difficult to measure experimentally. [...] Read more.
Selective laser melting (SLM) is an advanced additive manufacturing technique that can produce complex and accurate metal samples. Since the process performs local high heat input during a very short interaction time, the physical parameters in the solidification are difficult to measure experimentally. In this work, the microstructure evolution of Ti-6Al-4V alloy in additive manufacturing was studied. With the increase of scanning speed, the cooling rate and the temperature gradient of molten pool position increased, which was attributed to the gradual decrease of energy density. The phase-field simulation resulted in the overall microstructure morphology of columnar crystals owing to the very large temperature gradient and cooling rate obtained from the temperature field. Microsegregation was observed during dendritic formation, and the solute was enriched in the liquid phase near the dendritic tip and between the dendritic arms due to the lower equilibrium distribution coefficient. The scanning speed had an effect on the dendrite spacing. Full article
(This article belongs to the Special Issue Additive Manufacturing of Metals with Lasers)
Show Figures

Figure 1

Open AccessArticle
Influence of HIP Treatment on Mechanical Properties of Ti6Al4V Scaffolds Prepared by L-PBF Process
Metals 2019, 9(12), 1267; https://doi.org/10.3390/met9121267 - 27 Nov 2019
Abstract
To improve biocompatibility and mechanical compatibility, post-treatment is necessary for porous scaffolds of bone tissue engineering. Hot isostatic pressing (HIP) is introduced into post-treatment of metal implants to enhance their mechanical properties by eliminating residual stress and pores. Additionally, oxide film formed on [...] Read more.
To improve biocompatibility and mechanical compatibility, post-treatment is necessary for porous scaffolds of bone tissue engineering. Hot isostatic pressing (HIP) is introduced into post-treatment of metal implants to enhance their mechanical properties by eliminating residual stress and pores. Additionally, oxide film formed on the material surface can be contributed to improve its biocompatibility. Ti6Al4V porous scaffolds fabricated by laser-powder bed fusion (L-PBF) process is studied in this paper, their mechanical properties are measured by pressure test, and the macroscopic surface morphology and microstructure are observed by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). After HIP treatment, an oxide layer of 0.8 μm thickness forms on the surface of Ti6Al4V porous scaffolds and the microstructure of Ti6Al4V transforms from α’ phase to α + β dual-phase, as expected. However, the pressure test results of Ti6Al4V porous scaffolds show a definitely different variation trend of mechanical properties from solid parts, unexpectedly. Concerning Ti6Al4V porous scaffolds, the compression stiffness and critical stress improves clearly using HIP treatment, and the fracture morphology shows obvious brittle fracture. Both the strengthening and brittleness transition of Ti6Al4V porous scaffolds result from the formation of an oxide layer and an oxygen atom diffusion layer. The critical stress of Ti6Al4V porous scaffolds can be calculated by fully considering these two strengthening layers. To obtain a porous scaffold with specific mechanical properties, the effect of post-treatment should be considered during structural design. Full article
(This article belongs to the Special Issue Additive Manufacturing of Metals with Lasers)
Show Figures

Figure 1

Open AccessArticle
Construction of Cellular Substructure in Laser Powder Bed Fusion
Metals 2019, 9(11), 1231; https://doi.org/10.3390/met9111231 - 18 Nov 2019
Abstract
Cellular substructure has been widely observed in the sample fabricated by laser powder bed fusion, while its growth direction and the crystallographic orientation have seldom been studied. This research tries to build a general model to construct the substructure from its two-dimensional morphology. [...] Read more.
Cellular substructure has been widely observed in the sample fabricated by laser powder bed fusion, while its growth direction and the crystallographic orientation have seldom been studied. This research tries to build a general model to construct the substructure from its two-dimensional morphology. All the three Bunge Euler angles to specify a unique growth direction are determined, and the crystallographic orientation corresponding to the growth direction is also obtained. Based on the crystallographic orientation, the substructure in the single track of austenitic stainless steel 316L is distinguished between the cell-like dendrite and the cell. It is found that, with the increase of scanning velocity, the substructure transits from cell-like dendrite to cell. When the power is 200 W, the critical growth rate of the transition in the single track can be around 0.31 ms−1. Full article
(This article belongs to the Special Issue Additive Manufacturing of Metals with Lasers)
Show Figures

Figure 1

Review

Jump to: Research

Open AccessReview
Corrosion Behaviors of Selective Laser Melted Aluminum Alloys: A Review
Metals 2020, 10(1), 102; https://doi.org/10.3390/met10010102 - 09 Jan 2020
Abstract
Selective laser melting (SLM) is an ideal method to directly fabricate products with high geometrical complexity. With low density and good corrosion resistance, aluminum alloys are widely used as important structural materials. Microstructures and mechanical properties of SLMed aluminum alloys have been recently [...] Read more.
Selective laser melting (SLM) is an ideal method to directly fabricate products with high geometrical complexity. With low density and good corrosion resistance, aluminum alloys are widely used as important structural materials. Microstructures and mechanical properties of SLMed aluminum alloys have been recently widely studied. Corrosion behavior as a vital concern during the service of SLMed aluminum alloy parts has also drawn many attentions. Previous studies have found that SLM-processed aluminum alloys exhibit better corrosion resistance compared to the casted and wrought counterparts for both Al-Si alloys and high strength 2xxx Al alloys, which is mainly due to the unique microstructure features of SLMed Al alloys. For Al-Si alloys, with different shapes of Si networks, the different building planes show discrepant corrosion behaviors. Owing to the rougher surface with relatively larger numbers of defects, the as-printed surface is vulnerable to corrosion than the polished. Heat treatment has a negative effect on corrosion resistance due to the breakup of Si networks. The microstructure features correlated with the corrosion behaviors were also reviewed in this paper. Some suggestions on the future study of corrosion behaviors of SLMed Al alloys were put forward. Full article
(This article belongs to the Special Issue Additive Manufacturing of Metals with Lasers)
Show Figures

Figure 1

Open AccessReview
Review: The Impact of Metal Additive Manufacturing on the Aerospace Industry
Metals 2019, 9(12), 1286; https://doi.org/10.3390/met9121286 - 29 Nov 2019
Abstract
Metal additive manufacturing (AM) has matured from its infancy in the research stage to the fabrication of a wide range of commercial functional applications. In particular, at present, metal AM is now popular in the aerospace industry to build and repair various components [...] Read more.
Metal additive manufacturing (AM) has matured from its infancy in the research stage to the fabrication of a wide range of commercial functional applications. In particular, at present, metal AM is now popular in the aerospace industry to build and repair various components for commercial and military aircraft, as well as outer space vehicles. Firstly, this review describes the categories of AM technologies that are commonly used to fabricate metallic parts. Then, the evolution of metal AM used in the aerospace industry from just prototyping to the manufacturing of propulsion systems and structural components is also highlighted. In addition, current outstanding issues that prevent metal AM from entering mass production in the aerospace industry are discussed, including the development of standards and qualifications, sustainability, and supply chain development. Full article
(This article belongs to the Special Issue Additive Manufacturing of Metals with Lasers)
Show Figures

Figure 1

Back to TopTop