TY - JOUR
T1 - Crystal introducing mechanism in laser wire directed energy deposition fabricated Ti6Al4V
AU - Li, Jinghao
AU - Zhou, Xianglin
AU - Brochu, Mathieu
AU - Chekir, Nejib
AU - Sixsmith, J. J.
AU - Zhao, Yaoyao Fiona
N1 - Publisher Copyright:
© The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.
PY - 2025
Y1 - 2025
N2 - Metal additive manufacturing has been rapidly developed for more than 2 decades; however, the nucleation mechanism (or crystal introducing) in MAM processes has been a long-term unsolved problem. This work discusses the importance of nucleation in MAM and investigates the crystal introducing mechanism in laser wire DED fabricated Ti6Al4V. A sample matrix under different fabrication conditions is fabricated under three hypotheses (stress, heat accumulation, and the solid-state transformation). It is approved from different perspectives that the recrystallization is the main reason for the crystal introducing and formation, and it is a comprehensive result of the residual stress and reheating. A more detailed investigation was launched on the early stage of a recrystallized grain at the prior beta grain boundary. The formation tendency of the recrystallized grain indicates its strong dependency on the grain boundary alpha phase. Results also show that the recrystallization does not necessarily take place at the prior beta grain boundary area, and even without grain boundaries, a single beta crystal is still able to recrystallize under the fabrication condition of laser wire DED. Some of these recrystallized grains are able to participate into the following competitive grain growth, thus influence the solidification microstructure in the fabricated part dramatically.
AB - Metal additive manufacturing has been rapidly developed for more than 2 decades; however, the nucleation mechanism (or crystal introducing) in MAM processes has been a long-term unsolved problem. This work discusses the importance of nucleation in MAM and investigates the crystal introducing mechanism in laser wire DED fabricated Ti6Al4V. A sample matrix under different fabrication conditions is fabricated under three hypotheses (stress, heat accumulation, and the solid-state transformation). It is approved from different perspectives that the recrystallization is the main reason for the crystal introducing and formation, and it is a comprehensive result of the residual stress and reheating. A more detailed investigation was launched on the early stage of a recrystallized grain at the prior beta grain boundary. The formation tendency of the recrystallized grain indicates its strong dependency on the grain boundary alpha phase. Results also show that the recrystallization does not necessarily take place at the prior beta grain boundary area, and even without grain boundaries, a single beta crystal is still able to recrystallize under the fabrication condition of laser wire DED. Some of these recrystallized grains are able to participate into the following competitive grain growth, thus influence the solidification microstructure in the fabricated part dramatically.
KW - Metal additive manufacturing
KW - Recrystallization
KW - Solidification microstructure
UR - http://www.scopus.com/inward/record.url?scp=85197465902&partnerID=8YFLogxK
U2 - 10.1007/s40964-024-00701-1
DO - 10.1007/s40964-024-00701-1
M3 - Journal article
AN - SCOPUS:85197465902
SN - 2363-9512
VL - 10
SP - 1231
EP - 1241
JO - Progress in Additive Manufacturing
JF - Progress in Additive Manufacturing
ER -