Novel Alloys for Metal Additive Manufacturing

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Mechanical Engineering".

Deadline for manuscript submissions: closed (10 April 2022) | Viewed by 3042

Special Issue Editor

Forschungszentrum Juelich GmbH, Microstructure and Properties of Materials (IEK-2), Insititute of Energy and Climate Research (IEK), Jülich, Germany
Interests: alloy development; thermomechanical fatigue; fracture mechanics; creep; stress relaxation; metallic high temperature alloys
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Special Issue Information

Dear Colleagues,

The maximum performance of a material is reached when it has been tailored to the demands of the manufacturing process employed.

Typically, the alloys applied in metal additive manufacturing (AM) today were tailored for the particular needs of traditional, conventional manufacturing technologies. The utilization of such standard alloy feedstock powders often necessitates extensive and time-consuming post-build treatment to meet market performance requirements. Furthermore, many—especially high-performance—alloys are not suitable for recurring melting and solidification connected to AM processing. Sufficient material properties in the as-built and/or direct-aged condition would be highly desirable, because it would help eliminating expensive post-build processing.

Strikingly, almost 30 years after its invention, AM is still waiting for materials to enable the technology to reach its true potential. New and optimized alloys are needed to conquer the current challenges and to take advantage of the biggest future opportunity of metal AM manufacturing: the potential to produce functionally graded build-ups with variations in site‐specific material properties, according to case-specific component engineering necessities, by varying feedstock compositions and AM parameters. The thermal history that materials will undergo during such advanced AM fabrication will be extremely complex and involve combinations of rapid solidification, repeated (re)melting and tempering. The resulting microstructures and properties will not be less complex and will typically not match the ones encountered in conventional processing.

This Special Issue is focused on the development of new alloying philosophies, novel alloys and processing ideas for future metal AM processing.

Dr. Bernd Kuhn
Guest Editor

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Keywords

  • metal additive manufacturing
  • alloy development
  • processing
  • heat treatment
  • microstructure
  • properties

Published Papers (2 papers)

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Research

17 pages, 6900 KiB  
Article
Additive Manufacturing Potentials of High Performance Ferritic (HiperFer) Steels
by Torsten Fischer, Bernd Kuhn, Xiuru Fan and Markus Benjamin Wilms
Appl. Sci. 2022, 12(14), 7234; https://0-doi-org.brum.beds.ac.uk/10.3390/app12147234 - 18 Jul 2022
Viewed by 1271
Abstract
In the present study, the first tailored steel based on HiperFer (high-performance ferrite) was developed specifically for the additive manufacturing process. This steel demonstrates its full performance potential when produced via additive manufacturing, e.g., through a high cooling rate, an in-build heat treatment, [...] Read more.
In the present study, the first tailored steel based on HiperFer (high-performance ferrite) was developed specifically for the additive manufacturing process. This steel demonstrates its full performance potential when produced via additive manufacturing, e.g., through a high cooling rate, an in-build heat treatment, a tailored microstructure and counteracts potential process-induced defects (e.g. pores and cavities) via “active” crack-inhibiting mechanisms, such as thermomechanically induced precipitation of intermetallic (Fe,Cr,Si)2(W,Nb) Laves phase particles. Two governing mechanisms can be used to accomplish this: (I) “in-build heat treatment” by utilizing the “temper bead effect” during additive manufacturing and (II) “dynamic strengthening” under cyclic, plastic deformation at high temperature. To achieve this, the first HiperFerAM (additive manufacturing) model alloy with high precipitation kinetics was developed. Initial mechanical tests indicated great potential in terms of the tensile strength, elongation at rupture and minimum creep rate. During the thermomechanical loading, global sub-grain formation occurred in the HiperFerAM, which refined the grain structure and allowed for higher plastic deformation, and consequently, increased the elongation at rupture. The additive manufacturing process also enabled the reduction of grain size to a region, which has not been accessible by conventional processing routes (casting, rolling, heat treatment) so far. Full article
(This article belongs to the Special Issue Novel Alloys for Metal Additive Manufacturing)
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14 pages, 5008 KiB  
Article
Numerical Analysis of Laser Pattern Effects to Residual Stress on Metal 3D Printing
by Chang-ho Jung, Moon Gu Lee, Chanhyuk Nam and Yongho Jeon
Appl. Sci. 2022, 12(9), 4611; https://0-doi-org.brum.beds.ac.uk/10.3390/app12094611 - 04 May 2022
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Abstract
In this study, a metal 3D printing process was simulated using finite elements methods (FEM), and the specimens were printed under the same conditions. Subsequently, residual stress was measured to validate the results. The thermal-structure two-way coupled analysis confirmed the phenomenon that occurred [...] Read more.
In this study, a metal 3D printing process was simulated using finite elements methods (FEM), and the specimens were printed under the same conditions. Subsequently, residual stress was measured to validate the results. The thermal-structure two-way coupled analysis confirmed the phenomenon that occurred during the additive process, thereby allowing the residual stress to be calculated more realistically. In addition, to simulate the printing process, a subroutine was configured to account for the laser heat input path and layer. The process of stacking and hatching in a snake pattern for an area measuring 5 mm × 5 mm was simulated. Four cases with different rotation angles of the layer pattern were calculated using FEM. The specimens were printed compared with the analysis results. To verify the printed condition of the specimen, computed tomography was performed to confirm the appearance of pores and cracks in the specimen. Cracks appeared in the 180° specimen, and the cause was analyzed based on the analysis results. Subsequently, the residual stress was measured by an X-ray diffractometer and compared; it was confirmed that the average error of the specimen without cracks is 8.86%, which is similar to the analysis results. These results confirm that the FEM model conducted in this study can be used to analyze residual stress and cracks in a material, which are difficult to analyze in previous studies. The FEM model constructed in this study is expected to facilitate investigations into 3D printing phenomena as well as enable a more efficient process design. Full article
(This article belongs to the Special Issue Novel Alloys for Metal Additive Manufacturing)
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