scholarly journals New Aluminum Alloys Specifically Designed for Laser Powder Bed Fusion: A Review

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1007 ◽  
Author(s):  
Alberta Aversa ◽  
Giulio Marchese ◽  
Abdollah Saboori ◽  
Emilio Bassini ◽  
Diego Manfredi ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
State Of The Art ◽  
Complex Geometries ◽  
Low Density ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Laser Absorption ◽  
Powder Flowability ◽  
Am Processes

Aluminum alloys are key materials in additive manufacturing (AM) technologies thanks to their low density that, coupled with the possibility to create complex geometries of these innovative processes, can be exploited for several applications in aerospace and automotive fields. The AM process of these alloys had to face many challenges because, due to their low laser absorption, high thermal conductivity and reduced powder flowability, they are characterized by poor processability. Nowadays mainly Al-Si alloys are processed, however, in recent years many efforts have been carried out in developing new compositions specifically designed for laser based powder bed AM processes. This paper reviews the state of the art of the aluminum alloys used in the laser powder bed fusion process, together with the microstructural and mechanical characterizations.

scholarly journals Review of Laser Powder Bed Fusion of Gamma-Prime-Strengthened Nickel-Based Superalloys

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 996
Author(s):  
Olutayo Adegoke ◽  
Joel Andersson ◽  
Håkan Brodin ◽  
Robert Pederson
Keyword(s):  
Defect Formation ◽  
State Of The Art ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Cast Material ◽  
Creep Properties ◽  
Powder Bed ◽  
Gamma Prime ◽  
Cracking Mechanisms ◽  
Nonequilibrium Solidification

This paper reviews state of the art laser powder bed fusion (L-PBF) manufacturing of γ′ nickel-based superalloys. L-PBF resembles welding; therefore, weld-cracking mechanisms, such as solidification, liquation, strain age, and ductility-dip cracking, may occur during L-PBF manufacturing. Spherical pores and lack-of-fusion voids are other defects that may occur in γ′-strengthened nickel-based superalloys manufactured with L-PBF. There is a correlation between defect formation and the process parameters used in the L-PBF process. Prerequisites for solidification cracking include nonequilibrium solidification due to segregating elements, the presence of liquid film between cells, a wide critical temperature range, and the presence of thermal or residual stress. These prerequisites are present in L-PBF processes. The phases found in L-PBF-manufactured γ′-strengthened superalloys closely resemble those of the equivalent cast materials, where γ, γ′, and γ/γ′ eutectic and carbides are typically present in the microstructure. Additionally, the sizes of the γ′ particles are small in as-built L-PBF materials because of the high cooling rate. Furthermore, the creep performance of L-PBF-manufactured materials is inferior to that of cast material because of the presence of defects and the small grain size in the L-PBF materials; however, some vertically built L-PBF materials have demonstrated creep properties that are close to those of cast materials.

scholarly journals Fused Filament Fabrication of NiTi Components and Hybridization with Laser Powder Bed Fusion for Filigree Structures

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4399
Author(s):  
Johannes Abel ◽  
Anne Mannschatz ◽  
Robert Teuber ◽  
Bernhard Müller ◽  
Omar Al Noaimy ◽  
...  
Keyword(s):  
Fine Fraction ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Fused Filament Fabrication ◽  
New Production ◽  
Decomposition Products ◽  
Powder Bed ◽  
Design Options ◽  
Am Processes ◽  
Powder Fraction

The present study introduces an approach to the powder metallurgical shaping of a pseudo-elastic nickel–titanium (NiTi 44 alloy) combining two different additive manufacturing (AM) processes, namely fused filament fabrication (FFF) and laser powder bed fusion (LPBF), by manufacturing filigree structures on top of sintered FFF parts. Both processes start with commercial gas atomized NiTi powder, which is fractionated into two classes. Using the fine fraction with particle sizes <15 µm, robust thermoplastic filaments based on a non-commercial binder system were produced and processed to different auxetic and non-auxetic geometries employing a commercial standard printer. FTIR analysis for thermal decomposition products was used to develop a debinding regime. After sintering, the phase transformation austenite/martensite was characterized by DSC in as sintered and annealed state. Precipitates resulting from residual impurities were detected by micrographs and XRD. They led to an increased transformation temperature. Adjusting the oxygen and carbon content in the alloy remains a challenging issue for powder metallurgical processed NiTi alloys. Filigree lattice structures were built onto the surfaces of the sintered FFF parts by LPBF using the coarser powder fraction (15–45 µm). A good material bond was formed, resulting in the first known NiTi hybrid, which introduces new production and design options for future applications.

Insights on Laser Additive Manufacturing of Invar 36

2020 ◽  
pp. 71-93
Author(s):  
Mostafa Yakout ◽  
M. A. Elbestawi
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Additive Manufacturing ◽  
Coefficient Of Thermal Expansion ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Laser Additive Manufacturing ◽  
Powder Bed ◽  
Iron Nickel ◽  
Am Processes

Recently, additive manufacturing (AM) became a promising technology to manufacture complex structures with acceptable mechanical properties. The laser powder-bed fusion (L-PBF) process is one of the most common AM processes that has been used for producing a wide variety of metals and composites. Invar 36 is an austenite iron-nickel alloy that has a very low coefficient of thermal expansion; therefore, it is a good candidate for the L-PBF process. This chapter covers the state-of-the-art for producing Invar 36 using the L-PBF process. The chapter aims at describing research insights of using metal AM techniques in producing Invar 36 components. Like most of nickel-based alloys, Invar 36 is weldable but hard-to-machine. However, there are some challenges while processing these alloys by laser. This chapter also covers the challenges of using the L-PBF process for producing nickel-based alloys. In addition, it reports the L-PBF conditions that could be used to produce fully dense Invar 36 components with mechanical properties comparable to the wrought Invar 36.

scholarly journals Processability of Atypical WC-Co Composite Feedstock by Laser Powder-Bed Fusion

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 50 ◽  
Author(s):  
Mohaimen Al-Thamir ◽  
D. Graham McCartney ◽  
Marco Simonelli ◽  
Richard Hague ◽  
Adam Clare
Keyword(s):  
Laser Scanning ◽  
Single Layer ◽  
Scanning Speed ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Future Production ◽  
Laser Scanning Speed ◽  
First Time ◽  
Am Processes

Processing of tool materials for cutting applications presents challenges in additive manufacturing (AM). Processes must be carefully managed in order to promote the formation of favourable high-integrity ‘builds’. In this study, for the first time, a satelliting process is used to prepare a WCM-Co (12 wt.% Co) composite. Melting trials were undertaken to evaluate the consolidation behaviour of single tracks within a single layer. Tracks with continuous and relatively uniform surface morphology were obtained. These features are essential for high-quality AM builds in order to encourage good bonding between subsequent tracks within a layer which may reduce porosity within a 3D deposition. This study elucidates the formation of track irregularities, melting modes, crack sensitivity, and balling as a function of laser scanning speed and provides guidelines for future production of WCM-Co by laser powder-bed fusion.

scholarly journals Increasing the Productivity of Laser Powder Bed Fusion for Stainless Steel 316L through Increased Layer Thickness

2020 ◽  
Author(s):  
Alexander Leicht ◽  
Marie Fischer ◽  
Uta Klement ◽  
Lars Nyborg ◽  
Eduard Hryha
Keyword(s):  
Stainless Steel ◽  
Layer Thickness ◽  
Electron Backscatter Diffraction ◽  
Powder Layer ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Stainless Steel 316L ◽  
Powder Bed ◽  
Backscatter Diffraction ◽  
Am Processes

AbstractAdditive manufacturing (AM) is able to generate parts of a quality comparable to those produced through conventional manufacturing, but most of the AM processes are associated with low build speeds, which reduce the overall productivity. This paper evaluates how increasing the powder layer thickness from 20 µm to 80 µm affects the build speed, microstructure and mechanical properties of stainless steel 316L parts that are produced using laser powder bed fusion. A detailed microstructure characterization was performed using scanning electron microscopy, electron backscatter diffraction, and x-ray powder diffraction in conjunction with tensile testing. The results suggest that parts can be fabricated four times faster with tensile strengths comparable to those obtained using standard process parameters. In either case, nominal relative density of > 99.9% is obtained but with the 80 µm layer thickness presenting some lack of fusion defects, which resulted in a reduced elongation to fracture. Still, acceptable yield strength and ultimate tensile strength values of 464 MPa and 605 MPa were obtained, and the average elongation to fracture was 44%, indicating that desirable properties can be achieved.

scholarly journals The Influence of Particle Shape, Powder Flowability, and Powder Layer Density on Part Density in Laser Powder Bed Fusion

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 418
Author(s):  
Lukas Haferkamp ◽  
Livia Haudenschild ◽  
Adriaan Spierings ◽  
Konrad Wegener ◽  
Kirstin Riener ◽  
...  
Keyword(s):  
Particle Shape ◽  
Final Part ◽  
Powder Layer ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Layer Density ◽  
Hausner Ratio ◽  
Powder Flowability ◽  
Part Density

The particle shape influences the part properties in laser powder bed fusion, and powder flowability and powder layer density (PLD) are considered the link between the powder and part properties. Therefore, this study investigates the relationship between these properties and their influence on final part density for six 1.4404 (316L) powders and eight AlSi10Mg powders. The results show a correlation of the powder properties with a Pearson correlation coefficient (PCC) of −0.89 for the PLD and the Hausner ratio, a PCC of −0.67 for the Hausner ratio and circularity, and a PCC of 0.72 for circularity and PLD. Furthermore, the results show that beyond a threshold, improvement of circularity, PLD, or Hausner ratio have no positive influence on the final part density. While the water-atomized, least-spherical powder yielded parts with high porosity, no improvement of part density was achieved by feedstock with higher circularities than gas-atomized powder.

scholarly journals Intra- and Inter-Repeatability of Profile Deviations of an AlSi10Mg Tooling Component Manufactured by Laser Powder Bed Fusion

2018 ◽  
Vol 2 (3) ◽  
pp. 56 ◽  
Author(s):  
Floriane Zongo ◽  
Antoine Tahan ◽  
Ali Aidibe ◽  
Vladimir Brailovski
Keyword(s):  
Statistical Analysis ◽  
Additive Manufacturing ◽  
Stress Relief ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Metrological Investigation ◽  
Powder Bed ◽  
Manufacturing Procedure ◽  
Industrial Use ◽  
Am Processes

Laser powder bed fusion (LPBF) is one of the most potent additive manufacturing (AM) processes. Metallic LPBF is gaining popularity, but one of the obstacles facing its larger industrial use is the limited knowledge of its dimensional and geometrical performances. This paper presents a metrological investigation of the geometrical and dimensional deviations of a selected LPBF-manufactured component, according to the ASME Y14.5-2009 standard. This approach allows for an estimation of both the process capability, as per ISO 22514-4 standard, and the correlations between the part location in the manufacturing chamber and the profile deviations. Forty-nine parts, which are representative of a typical aerospace tooling component (30 mm in diameter and 27.2 mm in height) were manufactured from AlSi10Mg powder using an EOSINT M280 printer and subjected to a stress relief annealing at 300 °C for two hours. This manufacturing procedure was repeated three times. A complete statistical analysis was carried out and the results of the investigation show that LPBF performances for all geometrical variations of 147 identical parts fall within a range of 230 µm at a 99.73% level.

scholarly journals Laser powder bed fusion of aluminum alloys

2017 ◽  
Vol 23 (3) ◽  
pp. 276 ◽  
Author(s):  
Diego Manfredi ◽  
Róbert Bidulský
Keyword(s):  
Aluminum Alloys ◽  
Scanning Speed ◽  
Point Of View ◽  
Laser Source ◽  
Main Process ◽  
Powder Size ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Physical Point ◽  
Powder Bed

<p class="AMSmaintext">The aim of this study is to analyze and to summarize the results of the processing of aluminum alloys, and in particular of the Al-Si-Mg alloys, by means of the Additive Manufacturing (AM) technique defined as Laser Powder Bed Fusion (L-PBF). This process is gaining interest worldwide thanks to the possibility of obtaining a freeform fabrication coupled with high mechanical strength and hardness related to a very fine microstructure. L-PBF is very complex from a physical point of view, due to the extremely rapid interaction between a concentrated laser source and micrometric metallic powders. This generate very fast melting and subsequent solidification on each layer and on the previously consolidated substrate. The effects of the main process variables on the microstructure and mechanical properties of the final parts are analyzed: from the starting powder properties, such as shape and powder size distribution, to the main process parameters, such as laser power, scanning speed and scanning strategy. Furthermore, some examples of applications for the AlSi10Mg alloy are illustrated.</p>

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