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Title: Controlling microstructure in deposits fabricated using powder blown direct energy deposition technique

Abstract

The overall goal of this collaboration is to develop technologies to control grain morphology and microstructures of Inconel 718 components additively manufactured through the Direct Energy Deposition (DED) process (Identical to the LENS (laser engineered net shaping) processes) and to achieve equiaxed or near equiaxed grain structures. The phase1 technical collaboration was used to fabricate Inconel 718 builds with different process parameters, pre heat and scan strategies. The results were then rationalized using computational heat transfer and solidification models. Microstructural characterization showed that the aspect ratio of the grains can be reduced to less than 1.5, and that control of the grain sizes to within 50-100 μm could be potentially obtained by using an external source to preheat the substrate to 400 ̊C. Heat transfer models coupled with solidification models were used to rationalize the results which show that preheating lowered the temperature gradient thereby resulting in moving towards the equiaxed region of the columnar to equiaxed transition (CET) curve. The results demonstrate that higher preheat temperatures could be potentially used to obtain a truly equiaxed structure.

Authors:
 [1];  [1];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1459282
Report Number(s):
ORNL/TM-2018/866
CRADA/NFE-17-06745
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English

Citation Formats

Raghavan, Narendran, Jordan, Brian H., and Dehoff, Ryan R.. Controlling microstructure in deposits fabricated using powder blown direct energy deposition technique. United States: N. p., 2018. Web. doi:10.2172/1459282.
Raghavan, Narendran, Jordan, Brian H., & Dehoff, Ryan R.. Controlling microstructure in deposits fabricated using powder blown direct energy deposition technique. United States. doi:10.2172/1459282.
Raghavan, Narendran, Jordan, Brian H., and Dehoff, Ryan R.. Fri . "Controlling microstructure in deposits fabricated using powder blown direct energy deposition technique". United States. doi:10.2172/1459282. https://www.osti.gov/servlets/purl/1459282.
@article{osti_1459282,
title = {Controlling microstructure in deposits fabricated using powder blown direct energy deposition technique},
author = {Raghavan, Narendran and Jordan, Brian H. and Dehoff, Ryan R.},
abstractNote = {The overall goal of this collaboration is to develop technologies to control grain morphology and microstructures of Inconel 718 components additively manufactured through the Direct Energy Deposition (DED) process (Identical to the LENS (laser engineered net shaping) processes) and to achieve equiaxed or near equiaxed grain structures. The phase1 technical collaboration was used to fabricate Inconel 718 builds with different process parameters, pre heat and scan strategies. The results were then rationalized using computational heat transfer and solidification models. Microstructural characterization showed that the aspect ratio of the grains can be reduced to less than 1.5, and that control of the grain sizes to within 50-100 μm could be potentially obtained by using an external source to preheat the substrate to 400 ̊C. Heat transfer models coupled with solidification models were used to rationalize the results which show that preheating lowered the temperature gradient thereby resulting in moving towards the equiaxed region of the columnar to equiaxed transition (CET) curve. The results demonstrate that higher preheat temperatures could be potentially used to obtain a truly equiaxed structure.},
doi = {10.2172/1459282},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Jun 01 00:00:00 EDT 2018},
month = {Fri Jun 01 00:00:00 EDT 2018}
}

Technical Report:

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