On the Observation of Annealing Twins during Simulating β-Grain Refinement in Ti-6Al-4V High Deposition Rate AM with In-Process Deformation
| Autor: | Filomeno Martina, Christopher S. Daniel, J. Quinta da Fonseca, Jack Donoghue, Alistair Garner, Phil Prangnell, Alec Davis |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
010302 applied physics
Equiaxed crystals grain size Materials science Polymers and Plastics Annealing (metallurgy) recrystallization Metals and Alloys Recrystallization (metallurgy) 02 engineering and technology Plasticity 021001 nanoscience & nanotechnology Microstructure 01 natural sciences Grain size Electronic Optical and Magnetic Materials 0103 physical sciences Ceramics and Composites titanium Composite material additive manufacture 0210 nano-technology Crystal twinning texture Electron backscatter diffraction |
| Zdroj: | Donoghue, J, Davis, A E, Daniel, C S, Garner, A, Martina, F, Quinta Da Fonseca, J & Prangnell, P B 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, vol. 186, pp. 229-241 . https://doi.org/10.1016/j.actamat.2020.01.009, https://doi.org/10.1016/j.actamat.2020.01.009 |
| DOI: | 10.1016/j.actamat.2020.01.009 |
| Popis: | Additive Manufacture (AM) of Ti-6Al-4V frequently leads to undesirable, coarse, columnar β-grain structures with a strong 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} 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. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|