Evolution of the Microstructure of Laser Powder Bed Fusion Ti-6Al-4V During Post-Build Heat Treatment

The microstructure of additively manufactured Ti-6Al-4V (Ti64) produced by a laser powder bed fusion process was studied during post-build heat treatments between 1043 K (770 °C) and just above the β transus temperature 1241 K (1008 °C) in situ using high-energy X-ray diffraction. Parallel studies o...

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Bibliographic Details
Published in:Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2021-12, Vol.52 (12), p.5165-5181
Main Authors: Brown, D. W., Anghel, V., Balogh, L., Clausen, B., Johnson, N. S., Martinez, R. M., Pagan, D. C., Rafailov, G., Ravkov, L., Strantza, M., Zepeda-Alarcon, E.
Format: Article
Language:English
Subjects:
Acicular structure
Annealing
Beta phase
Characterization and Evaluation of Materials
Chemistry and Materials Science
Dislocation density
Electron backscatter diffraction
Evolution
Grain structure
Heat treating
Heat treatment
Low temperature
Materials Science
Metallic Materials
Microstructure
Nanotechnology
Original Research Article
Powder beds
Recovery
Residual stress
Structural Materials
Surfaces and Interfaces
Texture
Thin Films
Titanium base alloys
X-ray diffraction
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Summary:The microstructure of additively manufactured Ti-6Al-4V (Ti64) produced by a laser powder bed fusion process was studied during post-build heat treatments between 1043 K (770 °C) and just above the β transus temperature 1241 K (1008 °C) in situ using high-energy X-ray diffraction. Parallel studies on traditionally manufactured wrought and annealed Ti64 were completed as a baseline comparison. The initial and final grain structures were characterized using electron backscatter diffraction. Likewise, the initial texture, dislocation density, and final texture were determined with X-ray diffraction. The evolution of the microstructure, including the phase evolution, internal stress, qualitative dislocation density, and vanadium distribution between the constituent phases were monitored with in situ X-ray diffraction. The as-built powder bed fusion material was single-phase hexagonal close packed (to the measurement resolution) with a fine acicular grain structure and exhibited a high dislocation density and intergranular residual stress. Recovery of the high dislocation density and annealing of the internal stress were observed to initiate concurrently at a relatively low temperature of 770 K (497 °C). Transformation to the β phase initiated at roughly 913 K (640 °C), after recovery had occurred. These results are meant to be used to design post-build heat treatments resulting in specified microstructures and properties.
ISSN:1073-5623
1543-1940
DOI:10.1007/s11661-021-06455-7