Abstract
Creep rupture samples were fabricated by additive manufacturing (AM) via electron beam melting (EBM) to study the effects of grain morphology (equiaxed/columnar grains) and loading direction (longitudinal/transverse) with respect to build direction on creep deformation at 923 K (650 °C) with applied stresses of 580 and 600 MPa. The observed minimum creep rates and creep rupture lives of EBM Inconel 718 after post-processing by hot isostatic pressing (HIP) were found to be comparable to wrought material. The material with equiaxed grains exhibited low creep strain (2 pct) and short creep lifetimes (800 hours), whereas longer times (approximately 4500 hours) and high creep strain (up to 23 pct) were observed for material with columnar grains. The high stress exponent (n > 14) reflected the resistance to dislocation motion by γ” particles during creep. A precipitate-free zone (PFZ) was observed around the grain boundary δ phase. Creep damage occurred as voids and cracks in the PFZ. Optimal post-processing of EBM Inconel 718 material should be explored to prevent δ phase embrittlement.
| Original language | English |
|---|---|
| Pages (from-to) | 5107-5117 |
| Number of pages | 11 |
| Journal | Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science |
| Volume | 49 |
| Issue number | 10 |
| DOIs | |
| State | Published - Oct 1 2018 |
Funding
The authors thank Dr. Frederick List and Thomas Muth at Oak Ridge National Laboratory for their comments on this manuscript. The authors also thank Jeremy Moser for helping in conducting creep tests and Andres Rossy for obtaining the EBSD images. Further, the authors would like to acknowledge Dr. Anders Eklund at Qunitus Technologies for his help in providing the hot isostatic press capability to post-process the material used in this work. This research is sponsored by the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office, under Contract DE-AC05-00OR22725 with UT-Battelle, LLC. The authors thank Dr. Frederick List and Thomas Muth at Oak Ridge National Laboratory for their comments on this manuscript. The authors also thank Jeremy Moser for helping in conducting creep tests and Andres Rossy for obtaining the EBSD images. Further, the authors would like to acknowledge Dr. Anders Eklund at Qunitus Technologies for his help in providing the hot isostatic press capability to post-process the material used in this work. This research is sponsored by the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office, under Contract DE-AC05-00OR22725 with UT-Battelle, LLC. This manuscript has been authored [or, co-authored] by UT-Battelle, LLC, under Contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). This manuscript has been authored [or, co-authored] by UT-Battelle, LLC, under Contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energ y.gov/downloads/doe-public-access-plan). Manuscript submitted December 8, 2017. Article published online July 16, 2018
| Funders | Funder number |
|---|---|
| DOE Public Access Plan | |
| US Department of Energy | |
| UT-Battelle, LLC | |
| U.S. Department of Energy | |
| Advanced Manufacturing Office | DE-AC05-00OR22725 |
| Office of Energy Efficiency and Renewable Energy | |
| UT-Battelle |
