On the observation of annealing twins during simulating β-grain refinement in Ti–6Al–4V high deposition rate AM with in-process deformation

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dc.contributor.authorDonoghue, Jack
dc.contributor.authorDavis, Alec E.
dc.contributor.authorDaniel, Christopher S.
dc.contributor.authorGarner, Alistair
dc.contributor.authorMartina, Filomeno
dc.contributor.authorda Fonseca, João Quinta
dc.contributor.authorPrangnell, Phil B.
dc.date.accessioned2020-07-24T14:12:06Z
dc.date.available2020-07-24T14:12:06Z
dc.date.issued2020-01-08
dc.description.abstractAdditive 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 structureen_UK
dc.identifier.citationDonoghue J, Davis A, Daniel C, et al., (2020) On the observation of annealing twins during simulating β-grain refinement in Ti–6Al–4V high deposition rate AM with in-process deformation. Acta Materialia, Volume 186, March 2020, pp. 229-241en_UK
dc.identifier.issn1359-6454
dc.identifier.urihttps://doi.org/10.1016/j.actamat.2020.01.009
dc.identifier.urihttps://dspace.lib.cranfield.ac.uk/handle/1826/15593
dc.language.isoenen_UK
dc.publisherElsevieren_UK
dc.rightsAttribution 4.0 International*
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/*
dc.subjectTextureen_UK
dc.subjectRecrystallizationen_UK
dc.subjectTitaniumen_UK
dc.subjectGrain sizeen_UK
dc.subjectAdditive manufactureen_UK
dc.titleOn the observation of annealing twins during simulating β-grain refinement in Ti–6Al–4V high deposition rate AM with in-process deformationen_UK
dc.typeArticleen_UK

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