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Mechanical Properties of Additive Structures in Materials

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (30 November 2017) | Viewed by 27626

Special Issue Editor


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Guest Editor
Institute of Structural Materials, Swansea University, Bay Campus, Swansea SA1 8EN, UK
Interests: miniaturised testing; additive manufacturing (AM) processes; nickel superalloys (single crystals, polycrystalline); thermomechanical fatigue (TMF); fatigue lifting; failure analysis
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Special Issue Information

Dear Colleagues,

Additive layer manufacturing (ALM) is a rapidly-growing technology, receiving widespread attention from a multitude of industrial sectors for component repair and manufacturing. The emergence of ALM is linked to the significant benefits that the process can offer, compared to more conventional manufacturing processes, such as forging or casting. These include considerable cost savings due to less material wastage, short lead times and improved buy-to-fly ratios. ALM is a process that involves the net-shape fabrication of a three-dimensional structure by fusing powders with a high-energy heat source on a layer-by-layer basis to enable the production of highly intricate components that would not be possible with more traditional methods.

Now there is a considerable drive to realise the successful implementation of these technologies into high level critical parts but a comprehensive assessment is still required of the relationships between key process variables, geometries, resultant transient microstructures, and mechanical properties for any given component.

This Special Issue will collate a series of contributions from scientists around the world currently studying the mechanical behaviour of a variety of additive based materials and structures. It is my pleasure to invite you to submit a manuscript for this Special Issue. Full papers, communications, and reviews are all welcome.

Dr. Robert Lancaster
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

  • additive manufacturing
  • 3D printing
  • powder bed
  • material deposition
  • material addition
  • blown powder
  • metals
  • mechanical properties
  • damage mechanisms

Published Papers (3 papers)

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6194 KiB  
Article
Comparison of Microstructure and Mechanical Properties of Scalmalloy® Produced by Selective Laser Melting and Laser Metal Deposition
by Mustafa Awd, Jochen Tenkamp, Markus Hirtler, Shafaqat Siddique, Markus Bambach and Frank Walther
Materials 2018, 11(1), 17; https://doi.org/10.3390/ma11010017 - 23 Dec 2017
Cited by 128 | Viewed by 13246
Abstract
The second-generation aluminum-magnesium-scandium (Al-Mg-Sc) alloy, which is often referred to as Scalmalloy®, has been developed as a high-strength aluminum alloy for selective laser melting (SLM). The high-cooling rates of melt pools during SLM establishes the thermodynamic conditions for a fine-grained crack-free [...] Read more.
The second-generation aluminum-magnesium-scandium (Al-Mg-Sc) alloy, which is often referred to as Scalmalloy®, has been developed as a high-strength aluminum alloy for selective laser melting (SLM). The high-cooling rates of melt pools during SLM establishes the thermodynamic conditions for a fine-grained crack-free aluminum structure saturated with fine precipitates of the ceramic phase Al3-Sc. The precipitation allows tensile and fatigue strength of Scalmalloy® to exceed those of AlSi10Mg by ~70%. Knowledge about properties of other additive manufacturing processes with slower cooling rates is currently not available. In this study, two batches of Scalmalloy® processed by SLM and laser metal deposition (LMD) are compared regarding microstructure-induced properties. Microstructural strengthening mechanisms behind enhanced strength and ductility are investigated by scanning electron microscopy (SEM). Fatigue damage mechanisms in low-cycle (LCF) to high-cycle fatigue (HCF) are a subject of study in a combined strategy of experimental and statistical modeling for calculation of Woehler curves in the respective regimes. Modeling efforts are supported by non-destructive defect characterization in an X-ray computed tomography (µ-CT) platform. The investigations show that Scalmalloy® specimens produced by LMD are prone to extensive porosity, contrary to SLM specimens, which is translated to ~30% lower fatigue strength. Full article
(This article belongs to the Special Issue Mechanical Properties of Additive Structures in Materials)
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6325 KiB  
Article
Tensile Fracture Behavior and Failure Mechanism of Additively-Manufactured AISI 4140 Low Alloy Steel by Laser Engineered Net Shaping
by Hoyeol Kim, Zhichao Liu, Weilong Cong and Hong-Chao Zhang
Materials 2017, 10(11), 1283; https://doi.org/10.3390/ma10111283 - 09 Nov 2017
Cited by 26 | Viewed by 7366
Abstract
AISI 4140 powder was directly deposited on AISI 4140 wrought substrate using laser engineered net shaping (LENS) to investigate the compatibility of a LENS-deposited part with the substrate. Tensile testing at room temperature was performed to evaluate the interface bond performance and fracture [...] Read more.
AISI 4140 powder was directly deposited on AISI 4140 wrought substrate using laser engineered net shaping (LENS) to investigate the compatibility of a LENS-deposited part with the substrate. Tensile testing at room temperature was performed to evaluate the interface bond performance and fracture behavior of the test specimens. All the samples failed within the as-deposited zone, indicating that the interfacial bond is stronger than the interlayer bond inside the deposit. The fracture surfaces were analyzed using scanning electron microscopy (SEM) and energy disperse X-ray spectrometry (EDS). Results show that the tensile fracture failure of the as-deposited part is primarily affected by lack-of-fusion defects, carbide precipitation, and oxide particles inclusions, which causes premature failure of the deposit by deteriorating the mechanical properties and structural integrity. Full article
(This article belongs to the Special Issue Mechanical Properties of Additive Structures in Materials)
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8625 KiB  
Article
Effect of Molten Pool Size on Microstructure and Tensile Properties of Wire Arc Additive Manufacturing of Ti-6Al-4V Alloy
by Qianru Wu, Jiping Lu, Changmeng Liu, Hongli Fan, Xuezhi Shi, Jie Fu and Shuyuan Ma
Materials 2017, 10(7), 749; https://doi.org/10.3390/ma10070749 - 04 Jul 2017
Cited by 48 | Viewed by 6525
Abstract
Wire arc additive manufacturing (WAAM) technique is a cost-competitive and efficient technology to produce large structure components in industry domains. Mechanical properties are mainly dominated by the microstructure of the components, which is deeply affected by the molten pool size. In this work, [...] Read more.
Wire arc additive manufacturing (WAAM) technique is a cost-competitive and efficient technology to produce large structure components in industry domains. Mechanical properties are mainly dominated by the microstructure of the components, which is deeply affected by the molten pool size. In this work, to investigate the effect of the molten pool size on microstructure and mechanical properties of the components, a series of Ti-6Al-4V alloy blocks with different width of molten pool (WMP) ranging from 7 mm to 22 mm were deposited by adjusting the wire feed speed (WFS) from 100 cm/min to 500 cm/min. It is interesting to find that the macrostructure changes from columnar grains to equiaxial grains, and then returns to large columnar grains with the increase of WMP, which is mainly caused by the different cooling rates and thermal gradients. Nonetheless, the tensile properties of the components have a tendency to decline with the increase of WMP. Full article
(This article belongs to the Special Issue Mechanical Properties of Additive Structures in Materials)
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