scholarly journals Electron Beam Powder Bed Fusion of γ-Titanium Aluminide: Effect of Processing Parameters on Part Density, Surface Characteristics and Aluminum Content

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1093
Author(s):  
Juliane Moritz ◽  
Mirko Teschke ◽  
Axel Marquardt ◽  
Lukas Stepien ◽  
Elena López ◽  
...  
Keyword(s):  
Electron Beam ◽  
Titanium Aluminide ◽  
Laser Scanning ◽  
Aluminum Content ◽  
Titanium Aluminides ◽  
Electron Backscatter Diffraction ◽  
Raw Material ◽  
Powder Bed Fusion ◽  
Microstructural Investigation ◽  
Powder Bed

Gamma titanium aluminides are very interesting for their use in high-performance applications such as aircraft engines due to their low density, high stiffness and favorable high-temperature properties. However, the pronounced brittleness of these intermetallic alloys is a major challenge for their processing through conventional fabrication methods. Additive manufacturing by means of electron beam powder bed fusion (EB-PBF) significantly improves the processability of titanium aluminides due to the high preheating temperatures and facilitates complex components. The objective of this study was to determine a suitable processing window for EB-PBF of the TNM-B1 alloy (Ti-43.5Al-4Nb-1Mo-0.1B), using an increased aluminum content in the powder raw material to compensate for evaporation losses during the process. Design of experiments was used to evaluate the effect of beam current, scan speed, focus offset, line offset and layer thickness on porosity. Top surface roughness was assessed through laser scanning confocal microscopy. Scanning electron microscopy, electron backscatter diffraction (EBSD) and energy-dispersive X-ray spectroscopy (EDX) were used for microstructural investigation and to analyze aluminum loss depending on the volumetric energy density used in EB-PBF. An optimized process parameter set for achieving part densities of 99.9% and smooth top surfaces was derived. The results regarding microstructures and aluminum evaporation suggest a solidification via the β-phase.

Grain Morphology and Texture Development in a Co-Cr-Mo Alloy Fabricated by Powder Bed Fusion with an Electron Beam

2019 ◽  
Author(s):  
Yufan Zhao ◽  
Yuichiro Koizumi ◽  
Kenta Aoyagi ◽  
Daixiu Wei ◽  
Kenta Yamanaka ◽  
...  
Keyword(s):  
Electron Beam ◽  
Grain Morphology ◽  
Texture Development ◽  
Powder Bed Fusion ◽  
Powder Bed

scholarly journals Comparison of Phase Characteristics and Residual Stresses in Ti-6Al-4V Alloy Manufactured by Laser Powder Bed Fusion (L-PBF) and Electron Beam Powder Bed Fusion (EB-PBF) Techniques

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 796
Author(s):  
Aya Takase ◽  
Takuya Ishimoto ◽  
Naotaka Morita ◽  
Naoko Ikeo ◽  
Takayoshi Nakano
Keyword(s):  
Electron Beam ◽  
Residual Stresses ◽  
Cooling Rate ◽  
Process Parameters ◽  
Phase Evolution ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Solidification Temperature ◽  
Powder Bed ◽  
Β Phase

Ti-6Al-4V alloy fabricated by laser powder bed fusion (L-PBF) and electron beam powder bed fusion (EB-PBF) techniques have been studied for applications ranging from medicine to aviation. The fabrication technique is often selected based on the part size and fabrication speed, while less attention is paid to the differences in the physicochemical properties. Especially, the relationship between the evolution of α, α’, and β phases in as-grown parts and the fabrication techniques is unclear. This work systematically and quantitatively investigates how L-PBF and EB-PBF and their process parameters affect the phase evolution of Ti-6Al-4V and residual stresses in the final parts. This is the first report demonstrating the correlations among measured parameters, indicating the lattice strain reduces, and c/a increases, shifting from an α’ to α+β or α structure as the crystallite size of the α or α’ phase increases. The experimental results combined with heat-transfer simulation indicate the cooling rate near the β transus temperature dictates the resulting phase characteristics, whereas the residual stress depends on the cooling rate immediately below the solidification temperature. This study provides new insights into the previously unknown differences in the α, α’, and β phase evolution between L-PBF and EB-PBF and their process parameters.

scholarly journals Microstructure–property gradients in Ni-based superalloy (Inconel 738) additively manufactured via electron beam powder bed fusion

2021 ◽  
pp. 102121
Author(s):  
Bryan Lim ◽  
Hansheng Chen ◽  
Zibin Chen ◽  
Nima Haghdadi ◽  
Xiaozhou Liao ◽  
...  
Keyword(s):  
Electron Beam ◽  
Powder Bed Fusion ◽  
Powder Bed

scholarly journals Effect of Build Orientation on the Microstructure, Mechanical and Corrosion Properties of a Biodegradable High Manganese Steel Processed by Laser Powder Bed Fusion

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 944
Author(s):  
Martin Otto ◽  
Stefan Pilz ◽  
Annett Gebert ◽  
Uta Kühn ◽  
Julia Hufenbach
Keyword(s):  
Electron Backscatter Diffraction ◽  
Longitudinal Axis ◽  
Manganese Steel ◽  
Compressive Yield Strength ◽  
Powder Bed Fusion ◽  
Compression Tests ◽  
Laser Powder Bed Fusion ◽  
Corrosion Properties ◽  
Powder Bed ◽  
Manufacturing Technologies

In the last decade, additive manufacturing technologies like laser powder bed fusion (LPBF) have emerged strongly. However, the process characteristics involving layer-wise build-up of the part and the occurring high, directional thermal gradient result in significant changes of the microstructure and the related properties compared to traditionally fabricated materials. This study presents the influence of the build direction (BD) on the microstructure and resulting properties of a novel austenitic Fe‑30Mn‑1C‑0.02S alloy processed via LPBF. The fabricated samples display a {011} texture in BD which was detected by electron backscatter diffraction. Furthermore, isolated binding defects could be observed between the layers. Quasi-static tensile and compression tests displayed that the yield, ultimate tensile as well as the compressive yield strength are significantly higher for samples which were built with their longitudinal axis perpendicular to BD compared to their parallel counterparts. This was predominantly ascribed to the less severe effects of the sharp-edged binding defects loaded perpendicular to BD. Additionally, a change of the Young’s modulus in dependence of BD could be demonstrated, which is explained by the respective texture. Potentiodynamic polarization tests conducted in a simulated body fluid revealed only slight differences of the corrosion properties in dependence of the build design.

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