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Title: Feasibility of in situ controlled heat treatment (ISHT) of Inconel 718 during electron beam melting additive manufacturing

A novel technique was developed to control the microstructure evolution in Alloy 718 processed using Electron Beam Melting (EBM). In situ solution treatment and aging of Alloy 718 was performed by heating the top surface of the build after build completion scanning an electron beam to act as a planar heat source during the cool down process. Results demonstrate that the measured hardness (478 ± 7 HV) of the material processed using in situ heat treatment similar to that of peak-aged Inconel 718. Large solidification grains and cracks formed, which are identified as the likely mechanism leading to failure of tensile tests of the in situ heat treatment material under loading. Despite poor tensile performance, the technique proposed was shown to successively age Alloy 718 (increase precipitate size and hardness) without removing the sample from the process chamber, which can reduce the number of process steps in producing a part. Lastly, tighter controls on processing temperature during layer melting to lower process temperature and selective heating during in situ heat treatment to reduce over-sintering are proposed as methods for improving the process.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [4] ;  [6]
  1. Texas A & M Univ., College Station, TX (United States); Oak Ridge National Lab. (ORNL), Knoxville, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Univ. of Tennessee, Knoxville, TN (United States)
  4. Oak Ridge National Lab. (ORNL), Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Arcam AB (Sweden)
  6. Oak Ridge National Lab. (ORNL), Knoxville, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Additive Manufacturing
Additional Journal Information:
Journal Volume: 13; Journal Issue: C; Journal ID: ISSN 2214-8604
Publisher:
Elsevier
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Temperature Materials Lab. (HTML); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Manufacturing Demonstration Facility (MDF)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; additive manufacturing; electron beam melting; post-processing; Ni-base superalloy
OSTI Identifier:
1344984
Alternate Identifier(s):
OSTI ID: 1411453