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Prediction of grain structure evolution during rapid solidification of high energy density beam induced re-melting

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journal contribution
posted on 15.04.2020, 10:29 by TF Flint, C Panwisawas, Y Sovani, MC Smith, HC Basoalto
Grain boundary migration in the presence of concentrated sources of heat is a complex process that has a considerable impact on resultant material properties. A phase field model is presented incorporating thermal gradient and curvature driving force terms to predict how a poly-crystalline network evolves due to the application of such heat sources, as grain boundaries migrate due to local boundary curvature and time-varying thermal gradients. Various thermal scenarios are investigated, in both two and three dimensions. These scenarios include both partial and full penetration laser induced melting, the application of a linearly varying time-independent thermal field, and successive melting events where regions experience multiple melting and solidification cycles. Comparisons are made between the microstructures predicted by the proposed phase field method, during the various thermal scenarios, that agree with commonly observed phenomena. Particularly interesting is the ability to explain the differences in grain morphology between the full penetration and partial penetration welds using the phase field model and associated driving force magnitudes between the two scenarios. The model predicts the restoration of grain boundary networks in regions experiencing multiple melting events, and explains the differences in grain morphology due to the local curvature and thermal gradient effects.

Funding

The work presented in this manuscript is supported by the Engineering and Physical Sciences Research Council (EPSRC) under the “A whole-life approach to the development of high integrity welding technologies for Generation IV fast reactors” grant EP/L015013/1 and the “An Integrated computational materials engineering (ICME) approach to multiscale modelling of the fabrication and joining of powder processed parts” grant EP/P005284/1. The authors would like to thank Trevor Keller and the The Mesoscale Microstructure Simulation Project for the valuable discussions. The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.

History

Citation

Materials & Design Volume 147, 5 June 2018, Pages 200-210

Version

AM (Accepted Manuscript)

Published in

Materials & Design

Volume

147

Pagination

200 - 210

Publisher

Elsevier BV

issn

0264-1275

Acceptance date

14/03/2018

Copyright date

2018

Available date

15/03/2018

Publisher version

https://www.sciencedirect.com/science/article/pii/S0264127518302156

Language

en