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Abstract
Additive Manufacture (AM) of Ti-6Al-4V frequently leads to undesirable, coarse, columnar β-grain structures with a strong <100> fibre texture. In Wire-Arc AM (WAAM), it has been found that the application of a low plastic strain, by methods such as inter-pass rolling, can disrupt β columnar growth and produce a refined, equiaxed grain structure that is more randomly orientated. The origin of this desirable effect has been investigated by thermo-mechanical simulation, direct in-situ EBSD observation, as well as by real-time synchrotron X-ray diffraction (SXRD) during rapid heating. These complementary approaches have shown that, when starting with a WAAM microstructure, the grain refinement process produces a unique micro-texture represented by a four-pole motif symmetrically centred on the parent grain {100} orientations. These new β-grain orientations can be reproduced by a double {112}<111> twinning operation, which produces 12 new, unique, β-orientation variants. High-resolution orientation-mapping techniques and in-situ SXRD heating simulations suggest that the prior β does not twin during deformation, but rather the grain refinement and related texture may be caused by annealing twinning during β re-growth on rapid re-heating of the deformed AM microstructure. Although this is the first time such a unique texture has been observed in a deformed and β annealed Ti-6Al-4V material, it was only found to dominate under the unusual conditions that occur in AM of rapid heating – a fine, lightly deformed α transformation microstructure, with a very coarse starting β-grain structure.
Original language | English |
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Pages (from-to) | 229-241 |
Number of pages | 13 |
Journal | Acta Materialia |
Volume | 186 |
Early online date | 8 Jan 2020 |
DOIs | |
Publication status | Published - Mar 2020 |
Keywords
- additive manufacture
- titanium
- grain size
- recrystallization
- texture
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Dive into the research topics of 'On the Observation of Annealing Twins during Simulating β-Grain Refinement in Ti-6Al-4V High Deposition Rate AM with In-Process Deformation'. Together they form a unique fingerprint.Projects
- 2 Active
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[NEWAM] New Wire-Additive Manufacturing
Prangnell, P., Pickering, E., Robson, J. & Shanthraj, P.
25/06/18 → 24/06/24
Project: Research
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LightForm: Embedding Materials Engineering in Manufacturing with Light Alloys
Prangnell, P., Curioni, M., Haigh, S., Quinta Da Fonseca, J., Robson, J., Shanthraj, P. & Zhou, X.
1/10/17 → 18/10/23
Project: Research