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Title: Role of scan strategies on thermal gradient and solidification rate in electron beam powder bed fusion

Local microstructure control in electron beam powder bed fusion (EB-PBF) is of great interest to the additive manufacturing community to realize complex part geometry with targeted performance. The local microstructure control relies on having a detailed understanding of local melt pool physics (e.g., 3-D melt pool shape as well as spatial and temporal variations of thermal gradient (G) and solidification rate (R)). In this research, a new scan strategy referred to as ghost beam is numerically evaluated as a candidate to achieve the targeted G and R of IN718 alloy. The boundary conditions for simulations, including the speed (490 mm/s) and spatial locations of the beam within a given layer, are obtained by using series of snapshot images, recorded at 12,000 frames per second, using a high-speed camera. The heat transfer simulations were performed using TRUCHAS an open-source software deployed within a high-performance computational infrastructure. The simulation results showed that reheating at short beam on-time and time delay decreases both G and R. Local variation of R at the center of the melt pool trailing edge showed periodic temporal fluctuations. Finally, the ghost beam scan strategy was compared to other existing raster and spot scan strategies.
Authors:
ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [3] ; ORCiD logo [1] ;  [4]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Manufacturing Demonstration Facility; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division
  2. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Mechanical, Aerospace and Biomedical Engineering; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Computer Science and Mathematics Division
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Computer Science and Mathematics Division
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Manufacturing Demonstration Facility; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Mechanical, Aerospace and Biomedical Engineering
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Additive Manufacturing
Additional Journal Information:
Journal Volume: 22; Journal Issue: C; Journal ID: ISSN 2214-8604
Publisher:
Elsevier
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Additive manufacturing; Scan strategy; Melt pool; Solidification and remelting; In-situ monitoring; Numerical simulation
OSTI Identifier:
1458379

Lee, Yousub, Kirka, Michael M., Dinwiddie, Ralph Barton, Raghavan, Narendran, Turner, John A., Dehoff, Ryan R., and Babu, Sudarsanam Suresh. Role of scan strategies on thermal gradient and solidification rate in electron beam powder bed fusion. United States: N. p., Web. doi:10.1016/j.addma.2018.04.038.
Lee, Yousub, Kirka, Michael M., Dinwiddie, Ralph Barton, Raghavan, Narendran, Turner, John A., Dehoff, Ryan R., & Babu, Sudarsanam Suresh. Role of scan strategies on thermal gradient and solidification rate in electron beam powder bed fusion. United States. doi:10.1016/j.addma.2018.04.038.
Lee, Yousub, Kirka, Michael M., Dinwiddie, Ralph Barton, Raghavan, Narendran, Turner, John A., Dehoff, Ryan R., and Babu, Sudarsanam Suresh. 2018. "Role of scan strategies on thermal gradient and solidification rate in electron beam powder bed fusion". United States. doi:10.1016/j.addma.2018.04.038.
@article{osti_1458379,
title = {Role of scan strategies on thermal gradient and solidification rate in electron beam powder bed fusion},
author = {Lee, Yousub and Kirka, Michael M. and Dinwiddie, Ralph Barton and Raghavan, Narendran and Turner, John A. and Dehoff, Ryan R. and Babu, Sudarsanam Suresh},
abstractNote = {Local microstructure control in electron beam powder bed fusion (EB-PBF) is of great interest to the additive manufacturing community to realize complex part geometry with targeted performance. The local microstructure control relies on having a detailed understanding of local melt pool physics (e.g., 3-D melt pool shape as well as spatial and temporal variations of thermal gradient (G) and solidification rate (R)). In this research, a new scan strategy referred to as ghost beam is numerically evaluated as a candidate to achieve the targeted G and R of IN718 alloy. The boundary conditions for simulations, including the speed (490 mm/s) and spatial locations of the beam within a given layer, are obtained by using series of snapshot images, recorded at 12,000 frames per second, using a high-speed camera. The heat transfer simulations were performed using TRUCHAS an open-source software deployed within a high-performance computational infrastructure. The simulation results showed that reheating at short beam on-time and time delay decreases both G and R. Local variation of R at the center of the melt pool trailing edge showed periodic temporal fluctuations. Finally, the ghost beam scan strategy was compared to other existing raster and spot scan strategies.},
doi = {10.1016/j.addma.2018.04.038},
journal = {Additive Manufacturing},
number = C,
volume = 22,
place = {United States},
year = {2018},
month = {8}
}