Metal Additive Manufacturing: Metallic Materials and Advanced Structures

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Additive Manufacturing Technologies".

Deadline for manuscript submissions: 20 May 2024 | Viewed by 6832

Special Issue Editors


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Guest Editor
School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510641, China
Interests: selective laser melting; laser powder bed fusion

E-Mail Website
Guest Editor
School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510641, China
Interests: selective laser melting; additive manufacturing; porous structures; metal 3D printing
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

We are inviting submissions to a Special Issue on “Metal Additive Manufacturing: Metallic Materials and Advanced Structures”.

Additive manufacturing (AM), also known as 3D printing, is the process of joining materials to make objects layer upon layer from computer-aided design (CAD) model data, as opposed to subtractive manufacturing methods. It is a disruptive technology that can provide design flexibility, part customization and/or complexity, and versatile functionalities for future advanced manufacturing. Metal AM, which plays an increasingly important role in the AM field, has been advancing in industrial applications of aerospace, automotive, biomedical, energy, space, marine and offshore, molding and tooling, etc., due to the superior strength, hardness, and wear and heat resistance of metallic products as compared to those of polymeric and ceramic counterparts. Recently, rapid advances in metal AM have allowed the fabrication of metallic materials and structures for lightweight, non-assembly, bio-inspiration, and multiple functions, with the development of new methodologies and systems. Representative processes of metal AM include powder bed fusion, directed energy deposition, binder jetting, and sheet lamination, and will be further developed toward hybrid additive and subtractive manufacturing, multiple-energy-sources-aided manufacturing, and large-scale manufacturing techniques in the future. The development of metal materials and processes may also enable the achievement of multiscale, multifunctional and hierarchical structures with unusual and remarkable properties.

The growing metal AM community brings enormous opportunities and challenges for academic and industrial applications. This Special Issue is devoted to exploring cutting-edge research and recent advances in the field of metal AM, with a particular emphasis on interactions between materials and energy beams, novel structural properties, and applications.

Dr. Changhui Song
Dr. Changjun Han
Guest Editors

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Keywords

  • metal additive manufacturing
  • numerical simulation
  • alloy design
  • structure design
  • topology optimization
  • in situ monitoring
  • machine learning
  • applications

Published Papers (4 papers)

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Research

17 pages, 6633 KiB  
Article
Research on the Warping and Dross Formation of an Overhang Structure Manufactured by Laser Powder Bed Fusion
by Pengcheng Lin, Meng Wang, Vyacheslav A. Trofimov, Yongqiang Yang and Changhui Song
Appl. Sci. 2023, 13(6), 3460; https://doi.org/10.3390/app13063460 - 08 Mar 2023
Cited by 2 | Viewed by 1536
Abstract
Warping and dross formation are the main defects of an overhang structure formed by laser powder bed fusion. In order to study these defects, a seven−shaped overhang structure with different lengths and heights of the overhang was printed. The influence of the temperature [...] Read more.
Warping and dross formation are the main defects of an overhang structure formed by laser powder bed fusion. In order to study these defects, a seven−shaped overhang structure with different lengths and heights of the overhang was printed. The influence of the temperature and stress field on the overhang structure was investigated using a 3D finite element (FE) model. The results of the simulation showed that the molten pool in the powder support zone was much larger than the molten pool in the solid support zone. The molten pool sank due to the actions of gravity and the capillary force. This led to the powder melting, which then formed a droplet−like dross formation on the lower surface. The temperature difference between the regions led to a large residual stress. When the residual stress exceeded the material strength, warping deformation occurred in the top area, affecting the subsequent powder−laying process. The warping zone was remelted when the next layer was processed. As the number of forming layers increased, the thermal conductivity and stiffness increased continuously, and the deformation of the top area gradually decreased. The experiment results showed that the longer the overhanging length was, the more serious the warpage was. When the overhanging length was below 3 mm, the warping of the top area continued to decrease to zero as the building process proceeded. Meanwhile, the dross formation appeared at the bottom of the overhanging area in all experimental groups. Studying the process of warping and dross formation was helpful to understand the defect change process in the manufacturing process of an overhang structure. Full article
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14 pages, 6201 KiB  
Article
Development of Novel Semi-Stranded Windings for High Speed Electrical Machines Enabled by Additive Manufacturing
by Ahmed Selema, Mohamed N. Ibrahim and Peter Sergeant
Appl. Sci. 2023, 13(3), 1653; https://doi.org/10.3390/app13031653 - 28 Jan 2023
Cited by 6 | Viewed by 1879
Abstract
Recent advances in electrical machines and energy storage technologies make electric vehicles (EVs) feasible replacements to conventional internal combustion engines. One of the main challenges of high speed electrical machines is providing maximum output power with minimum energy losses, weight, and volume. At [...] Read more.
Recent advances in electrical machines and energy storage technologies make electric vehicles (EVs) feasible replacements to conventional internal combustion engines. One of the main challenges of high speed electrical machines is providing maximum output power with minimum energy losses, weight, and volume. At high frequency operation, the conductors of AC electrical machines can suffer from skin and proximity effects. This results in high AC losses in the machine windings and can eventually lead to machine failure. In this paper, a novel design for a semi-stranded coil is proposed to limit these undesirable effects. Enabled by additive manufacturing (AM) technology, this sophisticated design is 3D printed using ultralight aluminum alloy. Finally, the AC performance of this coil is measured and compared with conventional single-strand copper coil at different frequency levels. It is found that the proposed design can effectively limit the eddy current losses in the high frequency domain. Full article
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15 pages, 18208 KiB  
Article
Influence of Warm Isostatic Press Process on Mechanical Properties of a Part Fabricated by Metal Material Extrusion Process
by Byeong-Yeol Choi, Seong-Je Park, Yong Son, Seung-Jun Han, Hyung-Giun Kim, Il-Hyuk Ahn and Woo-Chun Choi
Appl. Sci. 2022, 12(23), 12240; https://doi.org/10.3390/app122312240 - 29 Nov 2022
Viewed by 1252
Abstract
Material extrusion (ME) using a filament including metal powders has recently attracted considerable attention because it allows the production of metal parts at low cost. However, like other additive manufacturing processes, metal ME suffers from the problem of internal pores. In this study, [...] Read more.
Material extrusion (ME) using a filament including metal powders has recently attracted considerable attention because it allows the production of metal parts at low cost. However, like other additive manufacturing processes, metal ME suffers from the problem of internal pores. In this study, warm isostatic pressure (WIP)—a post-process used to downsize or remove the pores in polymer ME—was employed in metal ME to improve the mechanical properties of the finished part. It was confirmed experimentally that the tensile strength and the strain at the ultimate tensile strength were increased by WIP. However, from hardness tests, two different results were obtained. On a microscopic scale, there was no change in hardness because the temperature of the WIP process was not high enough to change the microstructure, while on a macroscopic scale, the hardness changed owing to the collapse of the pores within the material under the indenter load. In specimens with relatively large pores, the hardness sensitivity increases with a larger indenter. Finally, factors affecting the WIP process parameters in metal ME were discussed. Full article
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17 pages, 7822 KiB  
Article
Influence of Laser Additive Manufacturing and Laser Polishing on Microstructures and Mechanical Properties of High-Strength Maraging Steel Metal Materials
by Haibing Xiao, Yongzhang Chen, Mingjun Liu, Yongquan Zhou, Chenlin Du and Wei Zhang
Appl. Sci. 2022, 12(20), 10340; https://doi.org/10.3390/app122010340 - 14 Oct 2022
Cited by 3 | Viewed by 1557
Abstract
To increase the surface quality of the high-strength maraging steel metal materials, a new method of executing the additive manufacturing process and subtraction polishing process of maraging steel metal materials was studied. The mechanical properties of maraging steel metal materials before and after [...] Read more.
To increase the surface quality of the high-strength maraging steel metal materials, a new method of executing the additive manufacturing process and subtraction polishing process of maraging steel metal materials was studied. The mechanical properties of maraging steel metal materials before and after laser powder bed fusion (LPBF) polishing were compared and analyzed. The influence of laser parameters on the formability of high-strength MS metal materials was studied, with MS additive parts successfully prepared. The initial surfaces had roughness values of 6.198–7.92 μm. The metal additive manufacturing parts were polished with double laser beams. Confocal microscopy, scanning electron microscopy, and X-ray diffraction were used to obtain the microstructure and phase composition of the microstructures. The microhardness of high-strength maraging forming parts by using a microhardness tester and the mechanical properties were analyzed. The results showed that the surface roughness was considerably reduced to lengthen the service life of the high-strength MS metal materials from an initial roughness of Sa = 6.3 μm to Sa = 0.98 μm, with the surface hardness increased and the martensite content decreased after using double-laser-beam polishing. Full article
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